|Dr. Adina Paytan
Research Professor, Institute of Marine Sciences
University of California, Santa Cruz
|Dr. Adrienne J. Sponberg
ASLO Director of Communications and Science
|Dr. Michael Pace
|Dr. Linda Duguay
Umeå University, Sweden
Climate Impacts Research Centre
University of Illinois at Urbana-Champaign
Employing a combined ancient DNA (aDNA) and environmental DNA (eDNA) approach to assess the impacts of multiple stressors on the aquatic diversity of a Swedish lake
Freshwater ecosystems are in rapid decline due to anthropogenic alterations (e.g., climate change, contaminants) and it is necessary to understand the effects of such changes in order to mitigate future impacts. The field of paleolimnology, which couples dated sediment cores deposited macrofossils, has been very success in documenting on how environmental changes (pH, temperature, etc.) have affected aquatic communities over time. More recently, the field of paleo-ecotoxicology, which combines paleolimnology and ecotoxicology, has begun to use dated sediment cores to examine how levels of contaminants have altered aquatic organisms and communities in the past. Here I proposed to combine paleo-ecotoxicology techniques with novel DNA technology to assess the effects of multiple stressors (e.g. temperature, mercury (Hg) concentrations) over time in a Swedish lake. More specifically, I will section and dated (210Pb) sediment cores collected from Lake Ala Lombolo in northern Sweden. From these sediment sections, I will measure Hg concentrations and extract ancient DNA (aDNA). Then I will relate Hg levels and historical temperature data to species composition from ancient DNA (aDNA) to examine how the aquatic invertebrate and fish communities have changed. Lastly, I will use environmental DNA (eDNA) filtered from water samples collected in Lake Ala Lombolo to determine current environmental conditions (e.g., temperature, Hg) and aquatic biodiversity. By integrating aDNA and eDNA with paleo-ecotoxicology techniques, I will provide a novel assessment of the effects of environmental change and contaminants on aquatic communities through time. This would be the first study to attempt such methodology and would provide the groundwork for future researchers.
Colorado State University
Climate change driven alterations in stratification and the impacts on communities dependent on inland fisheries
Climate change is reshaping patterns of stratification in lakes covering a wide range of latitudes and morphologies. In particular, changes in physical-chemical structure of the water column, such as warming epilimnions and decreasing oxygen content at depths can inflict irreparable damage to local fisheries and by extension, the communities who depend on them. To examine the complex relationship between stratification as a key component of lakes as natural resources and communities dependent on healthy fisheries, we will synthesize between-region and between-lake factors of two study locations, one tropical and one arctic. Though exceptionally different systems, Lake Yojoa, Honduras and the Abisko region of Sweden are both impacted by climate change in terms of warming surface waters and changes in stratification. Using a combination of modeled and observed patterns in stratification, fish harvest data and additional field work in the Abisko region, this collaboration will explore not only the relationship between stratification and fisheries yields but also develop a framework for asking questions aimed at the broader social and economic impacts. It is the goal of this research to not only quantitatively examine the relationship between physical-chemical structure of the water column and diminishing fisheries but also to explore the direct and indirect effects of stratification regimes on local communities. Some of the impacts we explore through this research include job provisioning in rural communities, the equity of reparations to the Sami people under changing fisheries conditions and the reassessment of protected habitat. This novel research will result in a publication detailing our findings, provide a springboard for additional research questions, and develop a framework to be used as a tool in promoting dialogue between researchers and stakeholders.
University of New Hampshire
CH4 Flux from Sub-arctic Mire Lakes: A Look at Relationships Between Microbial Communities and Submerged Aquatic Vegetation in Stordalen Mire Lakes
High latitude ecosystems are warming at a rapid rate, increasing permafrost thaw and thereby providing fresh sources of organic carbon (C) to post-glacial lakes. These lakes are a significant source of methane (CH4) emissions into the atmosphere, however little is known about the reason for the spatial variability in these emissions within and between lakes. Stordalen Mire is a 25-ha hydrologically connected system of lakes and wetlands in the discontinuous permafrost zone in northern Sweden. Strong correlations between methanotroph lineage ANME-2d and the isotopic composition of methane (δ13CH4) have been identified within lake sediments using 16S rRNA sequence data and sediment CH4concentration measurements. However, previous work in these lakes have shown no strong relationships between carbon sediment geochemistry and submerged aquatic macrophyte (SAM) vegetation. We have shown strong microbial correlations with CH4 and now ask what microbial-vegetation interactions between SAM vegetation and their associated microbial community exist in these lakes and how does that relate to measured CH4?The main objective of the proposed work is to complete incubation experiments to understand interactions between microbial communities and SAM vegetation in sub-arctic lakes. To investigate the effect of plant species on the CH4 flux from microbial communities we will construct plant-sediment microcosms and incubate them with CH4 at an initial concentration of 1% v/v for 32 hours at 25°C. Incubations will be performed with four SAM species (Potamogeton, chara, sparganium, andmyriophyllum) collected from two of the Abisko lakes (Inre Harrsjön and Mellersta Harrsjön)from both high and low CH4 emitting areas of the Inre Harrsjön and Mellersta Harrsjön. Plant and sediment samples will be analyzed for geochemical measurements in addition to metagenomic sequencing for microbial community profiles.
University of California, Davis
Spatial variance in global lake abundance estimates
Lakes play a large and underappreciated role in energy flow and material processing. Accurate global lake abundance and distribution inventories will be critical towards addressing macroecological questions regarding the role of hydrologic and biogeochemical processes, and in developing more accurate carbon and energy budgets for the planet. In this project, I propose a team-based synthesis project involving spatial comparisons of global lake counts. I will collate previously developed global and regional lake inventory databases into spatially explicit 1x1 degree grid cells. Using these data, I endeavor to estimate spatial variance measures in lake counts among datasets. The primary goal of this study would be an evaluation of which methods and regions in the world are most problematic for lake counting purposes. Central to the work would be the development of a lake counting team composed of a diverse mix of scientists at institutions primarily in Sweden and the USA, but likely other regions as well. Therefore, we would aim to promote team and synthesis science through the LOREX program. In addition to our comparative lake counting results, we would also create an open access database of lake inventory data by method, along with reproducible R code to facilitate others in freely using this information. Because these data and analyses have long been lacking, this project has the potential to greatly advance the fields of limnology, freshwater ecology, and the physical sciences.
University of Alabama
Using an arctic catchment-scale model of community structure and growth to predict impacts of climate change on stream macroinvertebrates
Arctic streams and the macroinvertebrates they host are at risk from future changes in climate. Rising temperatures will potentially increase riparian vegetation cover, decreasing light availability and thus autochthonous production. As a result, terrestrial (allochthonous) resources may begin to dominate, driving shifts toward lower food quality under warmer conditions. These compounding effects of temperature, light availability, and food quality will likely alter both stream macroinvertebrate community assemblage structure and individual growth rates. Growth rates are expected to increase with temperature, whereas communities will become dominated by more warm-adapted taxa. However, these predictions have not yet been tested in arctic streams, where future environmental changes are likely to be pronounced due to polar amplification of warming. Here, I propose to explore how temperature and organic resource supply interact to influence stream macroinvertebrates in the Miellajokka catchment of northern Sweden. This basin comprises a mix of vegetation types (tundra and birch forest) common in the Fennoscandian Arctic that provide a natural gradient in temperature, light, and aquatic productivity. To explore the importance of these drivers, I will characterize patterns in macroinvertebrate composition and growth rate of key taxa amongst streams in this catchment. I will evaluate how these biotic responses relate to catchment land cover, riparian vegetation, water temperature, and concurrent estimates of stream (algal) productivity. Using data on macroinvertebrate community composition and individual growth rates we can move toward modeling how future climate change will impact these vulnerable arctic ecosystems.
Dalhousie University, Canada
The Department of Oceanography
University of Massachusetts Boston
Interpreting River Discharge from Variations in Coastal Reflectance
Fluctuating river discharges are associated with climate change and other anthropogenic effects. Systematic, consistent measurements of river discharge are necessary for monitoring and managing river systems but gathering such in situ data at fine spatio-temporal scales can be logistically challenging and costly. Publicly available ocean color remote sensing imagery from high spatial resolution satellites can be used to monitor river systems. Thus, the goal of the proposed project is to evaluate remotely sensed proxies for river discharge using the Landsat 8 and Sentinel 2 satellites. The project objectives include: 1) compiling in situ and satellite datasets over the Connecticut River Estuary, 2) comparing Landsat 8 and Sentinel 2 reflectance in the red wavelengths with river discharge, and 3) comparing Landsat 8 and Sentinel 2 river widths to river discharge. The results from this work will help determine the applicability of remotely sensed proxies for river discharge estimation, and it will lay the groundwork for applying these proxies to other river systems.
Catherine (Catrina) Nowakowski
University of Rhode Island
Reconstructing fifty years of changes in nitrogen based export production dynamics in the Gulf of Maine using compound-specific isotope analysis
Over the next century, global oceans will continue to get warmer and more stratified. The resulting oceanographic conditions are expected to select for small-cell, microbial-loop dominated phytoplankton communities that will alter upper trophic level consumer population and trophic dynamics and weaken export production-fueled CO2 sequestration. Surface waters in the Gulf of Maine have warmed faster than 99.9% of the world’s oceans and this is expected to drive changes in the ecosystem from the bottom up. This rapid level of change, and the accumulation of long-term studies and modeling effort in the Gulf of Maine make it an ideal case study. By using recently collected corals (2017-2020) from the Gulf of Maine and cutting-edge compound-specific stable isotope analysis techniques, I propose to reconstruct a long term (fifty year), high resolution (annual) record of changes in the export production dynamics since the 1970s. Specifically, this project aims to 1) generate a timeseries of 𝛿 15𝑁 based metrics representing source nitrogen, trophic level, and microbial reworking, from Primnoa resedaeformis coral and 2) analyze the above metrics within the context of the broader Gulf of Maine trophic biology and nitrogen cycling. This will entail dating and sampling of coral growth rings, applying wet chemistry to hydrolyze and derivatize samples, and analyzing samples for amino acid-specific N isotopes in Dr. Owen Sherwood’s Stable Isotope Biogeochemistry Lab at Dalhousie University. I will then use time series analysis to analyze and interpret the data generated. Products from this work will directly contribute to the first chapter of my PhD and propel my future work forward.
University of Maine
Inverse Modeling of Nitrate Reduction Processes
Disruption of the global nitrogen (N) cycle has led to environmental problems and increased interest in the fate of N. Denitrification and anammox remove N from systems as dinitrogen, while dissimilatory nitrate reduction to ammonium (DNRA) retains N as ammonium. Controlling factors on the partitioning between these pathways need to be identified to determine the fate of N in the marine environment. Previous research indicates that availability of organic carbon (C) and nitrate (NO3-) impact partitioning, but there may be specific tipping points at which dominance between nitrate reduction pathways occur. With my advisor and in collaboration with Anne Giblin at the Marine Biological Laboratory and my proposed LOREX host Chris Algar at Dalhousie University, the goal of my study leading up to the LOREX internship is to determine if there are specific organic carbon to nitrate ratios (C:NO3-) at which dominance between nitrate reduction processes switches. During the LOREX internship, I propose to develop and build inverse models to interpret the results from a series of experiments testing the response of naturally occurring marine sediment microbial communities to various C:NO3-. The thin layer of sediment in the thin disc method allows for rapid exchange with the overlying water in a flow-through reactor with constant flux of NO3- to the sediment thin discs. Stable isotope techniques, using 13C and 15N additions, are being used to determine C utilization and denitrification, anammox, and DNRA rates. This experimental design allows quantification of a wide range of substrate ratios for C:NO3- and their effect on partitioning between NO3- reduction processes. In this internship, a model will be fit to the measured inorganic N species using denitrification and DNRA rates as parameters. This study will be used to understand partitioning between nitrate reduction processes and provide insights on its controlling factors.
Interuniversity Group in Limnology (GRIL)
Montréal, Québec, Canada
Portland State University
Variation of cyanobacteria communities across environmental gradients of temperature and nutrient loading in mountain lakes
Toxic cyanobacteria blooms are often considered a growing environmental health issue limited to lowland lakes in developed regions from increased nutrient runoff by human activity. Yet some remote mountain lakes are also experiencing blooms. High elevation-lakes are often exposed to increasing atmospheric deposition of nutrients due to surrounding industry, and in combination with rising temperatures due to a changing climate, cyanobacteria blooms may become more prevalent. However, the interactive effects of these environmental shifts on cyanobacteria communities in mountain lakes remains unclear. Therefore, the objective of my project is to characterize cyanobacteria communities of mountain lakes, using genomic sequencing, across a gradient of temperature and phosphorus to examine the potential trends of bloom-forming and toxin-producing strains. I expect to find the frequency of bloom-forming and toxin producing strains will correlated positively with temperature and phosphorus, a key limiting nutrient, as their growth rates have been shown to positively correlate with both factors. I also expect if these positive relationships are found that cyanobacteria diversity will be lowest at the highest temperatures and phosphorus concentrations as the bloom-formers and toxin producers dominate. I will sample 30 lakes along an elevational (temperature) and phosphorus gradient in the Cascade Range in Oregon, where many lakes have observable cyanobacteria blooms. I will extract DNA from samples for sequencing of the bacterial 16s rRNA gene and sequence processing to identify cyanobacteria at the strain level. By examining the structural variation between lake communities and the potential interacting relationships with temperature and phosphorus, I will determine how these changing abiotic factors may influence the incidence of blooms as well as toxin production in mountain lakes. Ultimately, this data combined with an international cyanobacteria sequence database, maintained at University of Montreal, can address variation of harmful blooms at a global scale.
Carrie Ann Sharitt
Effects of increasing temperature and parasites on nutrient excretion by pumpkinseed
Consumers play an important role in nutrient cycling in many aquatic ecosystems as they release nutrients such as nitrogen and phosphorus largely through excretion and egestion. These nutrients are ecologically important within aquatic ecosystems and in some cases make a significant contribution to whole ecosystem flux. Factors such temperature and population biomass are known to impact the overall amount of nutrients released from aquatic consumers. However, little is known about how parasites impact nutrient excretion from aquatic consumers; yet, parasites will increase in abundance and intensity under many climate change models. Therefore, understanding the synergistic influence of climate warming and parasite burden on animal excretion remains an open question. In lakes of the southern boreal, which have been subject to reduced ice-cover and rising temperature, pumpkinseed sunfish (Lepomis gibbosus) are common and abundant fish. In some lakes, these fish are infected by a trematode, Uvulifer ambloplitis. Working at Station de Biologie des Laurentides, pumpkinseed will be exposed to temperatures increases (2°C and 4°C) as well as various trematode infection burdens (uninfected, low intensity, and high intensity). After allowing the fish to acclimate for several weeks, nutrient excretion will be measured across treatments. A subsample of fish will also be used to understand how warming temperatures and parasites alter stoichiometry of fish body tissues. We anticipate that nutrient excretion will increase with elevated parasite burden and higher temperatures and that parasite’s stoichiometry will influence that of its host.
Southern Cross University, Australia
University of Southern Mississippi
Does submarine groundwater discharge (SGD) drive hypoxia in coastal waters?
Submarine groundwater discharge (SGD) is the combined flow of freshwater from aquifers and the recirculation of seawater through sediments that occurs along the coastline and across the continental shelf. Submarine groundwater discharge is an important part of global nutrient, trace metal, and carbon inputs to the ocean. SGD can greatly affect the water quality of coastal environments, especially in areas that are already vulnerable to eutrophication and hypoxia. Intermittently Closed and Open Lakes or Lagoons (ICOLLs), also known as coastal lagoons or estuaries in some regions, are common ecosystems along the world’s shorelines. They are often closed off to the coastal ocean and routinely are affected by hypoxic conditions. Previous work done along the coast of Australia has indicated that groundwater may be up to 90% of water input to ICOLLs. I will build on this work by assessing whether SGD drives widespread hypoxia in ICOLLs. I selected four Australian ICOLLs with different levels of anthropogenic impact to determine the relationship between SGD and dissolved oxygen content. Radon, radium, nutrients, nutrient/water isotopes, and physical parameters within each ICOLL will be determined to understand the effects of SGD and the surrounding land use on the water quality. These are highly sensitive estuarine environments, and understanding the fluxes that can affect water quality will be useful in protecting and maintaining them. The work will build on my ongoing PhD research by strengthening the idea that SGD and hypoxia are linked, and will create an opportunity to collaborate with a leading research group working on related topics.
Stephanie J. Wilson
Virginia Institute of Marine Science
Are subterranean estuaries a source or sink of nitrogen to the coastal ocean?
Coastal zones are often plagued by elevated nutrient inputs causing harmful algal blooms, eutrophication, and dead zones. Nutrient sources include rivers, surface water runoff, and submarine groundwater discharge (SGD). SGD, a mixture of groundwater and seawater, is released from subterranean estuaries (STEs) at coastlines. Despite being identified as having high nitrogen (N) concentrations, SGD is often overlooked as a source of N to the ocean. N speciation and concentration in SGD are influenced by physical and biogeochemical processes along the groundwater flow path and within STEs. A body of literature presenting N speciation and concentration is available from STEs around the world, but there has not been an attempt to synthesize these data and to relate them to sources and fates of SGD N. During my time in Australia, I will collaborate with Dr. Isaac Santos on the construction of a global dataset with the goal of writing a meta-analysis paper on the concentrations, sources, and fates of N species in STEs. Speciation and concentration along STE gradients will determine the N in SGD which may be derived directly from groundwater (“new”) or from remineralization of organic matter in the STE (“recycled”). Concentrations of each N species will be analyzed using conservative mixing curves to determine the source or sink behavior of STEs. I will advance our knowledge on how biological and physical factors regulate N as it moves from groundwater, through the STE, and into the ocean, which will have implications for understanding the global ocean N budget. The proposed project will compliment Dr. Santos’ current meta-analysis of carbon in SGD allowing for comparisons between STE carbon and N. My stay in Australia will also allow me to participate in field and laboratory investigations with other graduate students in my supervisor’s group, providing opportunities for networking and co-authored publications.
Southern Cross University, Australia
Southern Cross University at Lismore
Alia N. Al-Haj
Building a methane budget for a subtropical seagrass ecosystem
Seagrasses play an important role in the marine carbon cycle burying 10x more carbon than terrestrial forests. However, there is little information on carbon lost from seagrasses via methane (CH4) emissions. The few studies that have quantified diffusive methane fluxes from seagrasses report that these ecosystems are methane sources. While there are a small number of studies on diffusive air-sea emissions of CH4 from seagrasses, to date there is little understanding of methane transport pathways in seagrass ecosystems. Methane can be transported from the sediments to the water column (then atmosphere) via diffusive sediment fluxes, ebullition, or (potentially) plant-mediated pathways. The importance of each pathway has implications for the balance between CH4 production, oxidation and emission to the atmosphere. If ebullition and plant-mediated pathways are significant in seagrasses, then the paradigm that much of the CH4 produced in marine sediments is oxidized during diffusive transport may need to be revised for these ecosystems. My Ph.D. research focuses on quantifying mechanisms for methane transport, formation, and oxidation in seagrass ecosystems. My proposed LOREX project is to conduct one field expedition and one microcosm experiment in collaboration with Dr. Damien Maher at Southern Cross University. The field expedition and experiment will address the following objectives: (1) Quantify sediment-water column, air-sea, microbubble, and ebullitive fluxes of CH4 from seagrass and unvegetated sediments, (2) Use δ13C-CH4 and δ13C-CO2 to determine the pathway for methanogenesis and quantify methane oxidation in seagrass and unvegetated sediments, (3) Determine if plant-mediated transport of CH4 occurs in seagrasses, and (4) Develop a CH4 budget for seagrass dominated areas of a subtropical basin. My results will help determine the dominant physical mechanisms for CH4 transport in seagrass meadows and will help determine a more accurate carbon storage capacity of seagrass meadows.
Kalina C. Grabb
MIT/Woods Hole Oceanographic Institution
Characterizing the role of superoxide in redox reactions with Fe(III)-bearing mineral transformations
Reactive oxygen species (ROS) are produced via various abiotic and biologic pathways and can therefore be vital to many biogeochemical processes and redox transformations. Due to the high reactivity of one such ROS, superoxide, it has been seen to play a role in the redox chemistry of metals (i.e. iron, Fe). For example, the reduction of Fe(III) to Fe(II) can be coupled with superoxide oxidation. While this is predicted to increase bioavailable Fe(II), there lacks a complete analysis on mineral dissolution under mildly reducing environments that simulate natural marine ecosystems. Since superoxide has the potential to alter redox environments, under controlled settings, various levels of superoxide production can simulate changing redox conditions. Therefore, this study proposes to monitor the iron transformation reactions within Fe(III)-bearing minerals under varying superoxide concentrations. A variety of Fe(III)-bearing minerals will be tested, focusing on those commonly found in marine environments that have varying redox potential (i.e. Fe-oxides, Fe-rich clays, and natural dust). Through a matrix of experiments in oxic artificial seawater, each mineral will be exposed to varying levels of superoxide. The sources of superoxide will include both an amperometric electrode and superoxide thermal sources (SOTS). Before and after the experiments, the minerals will be analyzed through a suite of methods, allowing for classification of the mineral composition and redox state. The overall goal of this study is to observe the alterations in superoxide dynamics and mineral composition and structure under mildly reducing environments. It is expected that the variance in superoxide concentration will closely simulate the redox conditions within natural marine ecosystems and thus provide a more accurate understanding of the redox processes that control mineral dissolution and metal speciation. Overall, understanding these processes can have large implications on biogeochemical cycling, bioavailable nutrients, and pollutant dynamics.
Josué G. Millán
Indiana State University
Assessing the importance of mixotrophy in deep dwelling calcifying marine phytoplankton
Anthropogenic activity has abruptly increased the concentration of the greenhouse gas CO2 in the atmosphere, modifying the geochemical cycling of carbon. Global warming and ocean acidification are two of the major consequences that we are witnessing. In the oceans, phytoplankton use CO2 and its dissociation product HCO3- upon CO2 dissolution in seawater for photosynthesis and calcification. In the surface ocean photosynthesis locks carbon into organic matter that after cell death or predation will partly sink to depth. This process of CO2 transport is commonly referred to as the Biological Carbon Pump. In contrast, the production of calcium carbonate (CaCO3) by calcification results in the production of CO2. Hence this process is termed the CaCO3 counter pump, and the relative strength of both determines atmospheric CO2 gas exchange. Among phytoplankton species, coccolithophores, cosmopolitan unicellular algae, are capable of doing both photosynthesis and calcification. The contribution of coccolithophores to the C cycle as calcifying autotrophs in the surface ocean is well studied, but their role in the lower photic zone remains uncertain. Besides, some lower photic species of coccolithophores are probably not obligate autotrophs but may show different levels of mixotrophy. We hypothesize that the mixotrophic capacity of coccolithophore species is critical in the biogeochemical cycling of C in the lower photic zones because of the low light availability, yet evidence for calcifying bloom-like events. Here we will assess the degree of mixotrophy of key deep dwelling coccolithophores in mono-clonal culture experiments, allowing to determine the importance of respiration for CaCO3production in this understudied realm.
Inter University Institute for Marine Science in Eilat, Israel
University of Wisconsin-Madison
Morphological shifts in Red Sea Rabbitfish associated with the invasion of the Mediterranean Sea
Invasive species threaten the biodiversity of ecosystems across the globe. However, they also provide a unique opportunity to study biological adaptation at a reasonable timescale since conditions (abiotic and biotic) change rapidly during invasions. Here, I’ll use the invasion of Red Sea species to the Mediterranean via the 1869 Suez Canal construction (Lessepsain Migration) to understand the long-term dynamics of inter- and intra-species trait variation and adaptation, specifically body morphology. Focusing on two prolific species of Rabbitfish (Siganus luridus and S. rivulatus), I will elucidate how body morphologies have changed throughout their ~60 years of invasion. Firstly, I will collect Rabbitfish samples in their native coral reefs in Eilat, Israel, where I will sample from varying habitats to better understand morphological drivers in their native range. Complimentary to samples from their native range, I will use the extensive preserved fish collection at the Tel Aviv Zoological Museum to study how morphology has changed in Rabbitfish in their invaded range of the Mediterranean over time. Together, these two datasets will be used to not only display how physical shape has changed over time, but also to understand shifts in morphological diversity within and among the Rabbitfish species. This study is unique as there are very few opportunities to detail how a species changes throughout an invasion at this magnitude. Further, this study could provide key insights to our understanding of individual trait variation’s role in biodiversity and ecosystem stability, which is currently a hallmark topic in ecology given the vast anthropogenic threats to the natural world.
MIT/Woods Hole Oceanographic Institution
Nuclei-induced calcium carbonate precipitation in the Red Sea
A fundamental pathway in the marine carbon cycle is the formation of calcium carbonate (CaCO2), which is typically attributed to biological calcification of shells and skeletons. While most surface seawater in both open and coastal oceans is supersaturated with CaCO3, abiotic CaCO3 precipitation is inhibited by several factors including the presence of dissolved organic carbon or Mg2+, such that abiotic CaCO3 precipitation is typically assumed to be an insignificant pathway in carbon cycling. However, laboratory experiments have shown that seeding solid particles into seawater supersaturated with CaCO3 promotes nuclei-induced CaCO3 precipitation, or NICP, and abiotic CaCO3 precipitation has been observed in Little Bahama Banks during resuspension of CaCO3 rich sediments. In the Red Sea, suspension of particles from flash floods and bottom sediments into the water column through storm events has been linked to NICP. As coastal oceans are typically supersaturated in carbonate and suspended sediment loads may be high, then it is important to constrain the degree to which NICP impacts coastal carbon cycling. The goal of this project is to evaluate the significance of NICP caused by flood sediment and dust resuspension in coastal waters. We propose a series of coastal mesocosm experiments using bottle samples and a suite of in-situ chemical sensors (pH, pCO2, and a newly developed dissolved inorganic carbon sensor from Woods Hole Oceanographic Institution (CHANOS II) to track high resolution carbonate precipitation during simulated flood and airborne dust deposition events. This in-situ study in the coastal Red Sea at Eilat, Israel, will take advantage of the warm water temperatures and high CaCO3 supersaturation combined with large particle loads from the surrounding desert, and will complement ongoing laboratory NICP experiments varying sediment load, CaCO3 content, and grain size.
University of Haifa, Israel
The Leon H. Charney School of Marine Sciences, Haifa
Texas A&M University at Galveston
Role of desalination plants in altering microbial activities: potential excess exudate production in response to effluents from the Hadera desalination plant
As the population grows, the need for alternative freshwater resources will become increasingly urgent. Currently, thousands of seawater reverse osmosis (SWRO) plants are in operation worldwide working to supply desalinated water where traditional resources have been depleted. The main byproduct of these desalination plants is a concentrated brine solution that is disposed of as effluent and returned to the coastal environment from which it was originally sourced. The brine effluent is characterized as having higher salt concentrations and warmer temperatures than the coastal environment into which it is disposed and often contains chemicals used during the desalination process. Understanding the environmental impacts SWRO plants have on the phytoplankton community inhabiting the coastal ecosystem is integral in ensuring the sustainability and efficiency of the desalination process. For example, when phytoplankton are subject to stressful environmental conditions, they may increase their transparent exopolymeric particle (TEP) production. TEP is known to enhance biofouling problems within desalination plants. Consequently, this may also negatively affect the efficiency of the plant itself. In addition, changes to the phytoplankton community could facilitate the occurrence of a harmful algal bloom. This would halt a desalination plant’s production all together. The objective of this study is to see if changes in water quality caused by a desalination plant affect coastal phytoplankton communities in such a way that would negatively affect the plant itself. I will conduct in situ transect sampling and perform bioassays along the coast of a desalination plant in Israel. Measurements will be taken to analyze phytoplankton physiological responses to conditions commonly associated with SWRO effluent. These methods will allow me to test the hypothesis: brine water effluent from desalination plants affect the microbial community in the receiving waters of the coastal environment, and in turn, the desalination plant.
University of Maryland
Exploring Seawater Strontium-Calcium Ratio Variability in the Gulf of Aqaba and the Eastern Mediterranean
Coral skeletal geochemistry is widely used to reconstruct (sub)tropical climate variability, a key component of the climate system. The Red Sea is a unique site for coral paleoclimate studies due to its healthy coral communities positioned at abnormally high latitudes, as well as its demonstrated sensitivity to climate patterns across the Mediterranean-European-Middle Eastern region. Coral paleoclimate reconstructions from the Red Sea have historically focused on coral skeletal isotopic composition (δ18O), which is sensitive to both sea surface temperature (SST) and seawater δ18O. A recent study from this region demonstrated the benefit of pairing coral δ18O with strontium-to-calcium ratios (Sr/Ca), which help to explicate the complex regional climate by subtracting the temperature signal from the coral δ18O. Coral Sr/Ca is also a function of seawater Sr/Ca, which is often assumed constant in oligotrophic environments. However, preliminary results from my master’s thesis in the Florida Keys indicate significant variations in seawater Sr/Ca within an oligotrophic, evaporative, carbonate coastal regime. Furthermore, a recent study demonstrated a latitudinal dependence on the coral Sr/Ca-SST calibration in the Red Sea. My work indicates that a change in local seawater Sr/Ca, dependent upon the Red Sea’s antiestuarine circulation, could be the cause. I propose a pilot study to examine seawater Sr/Ca variability at Eilat in the Gulf of Aqaba, one of the most prominent sites for coral paleoclimate research in the northern Red Sea. Simultaneous measurements made in the Mediterranean Sea near Haifa, Israel will provide an important comparison for another anti-estuarine body of water in the region, as well as provide context for how the opening of the Suez Canal could have potentially changed background seawater Sr/Ca ratios for the northern Red Sea and the Gulf of Aqaba. The results from this study will provide important information for the emerging coral Sr/Ca-based paleoclimatology in the region.
University of Massachusetts-Dartmouth
Phytoplankton C:N:P Ratios and Isotopic Composition in the Eastern Mediterranean Sea
The objectives of this study are to measure taxa-specific variability and the variation of phytoplankton C:N:P ratios in the EMS with regards to natural and manipulated difference in N:P supply ratio, and to determine which phytoplankton taxa are dominant drivers of carbon export in the EMS. This will be done using newly developed flow cytometric and isotope geochemistry techniques to samples collected from the Levantine basin with a high NO3-:PO4-3 supply of about >32:1, from coastal EMS eutrophic stations, and from experimental mesocosms with varying N:P. This study will be the first taxa-specific C:N:P and N isotopic signatures of phytoplankton in the EMS. Our results will be accompanied by nutrient supply data and δ15N values for NO3- and sediment trap samples. These results enhance our understanding of the detailed interaction between phytoplankton ecophysiology and the flux and composition of deeply sinking material. This can serve to improve predictive regional and global models of ocean biogeochemistry.
The implications of multiple stressors on the chemical signatures of reef-building coral
The first appearance of corals in the fossil record was approximately 535 million years ago, and overtime, coral reefs have evolved to be the most diverse and important ecosystem in the oceans. Despite their intrinsic value, coral reefs are under major threat from climate change related effects. Corals can boast their accomplishments while living in oligotrophic waters because of their symbionts and complex microbiome. Very little is known about the interactions between the coral host, photosymbionts, and microbiome, especially in terms of metabolic activity and chemistry. Metabolomic research on corals is very novel and often unguided. Additionally, almost all previous and current studies focus on coral response to one stressor at a time, but wild corals will not simply be exposed to one stressor. For these reasons, the objectives of my proposed project aim to determine the metabolic activity of the coral holobiont in response to multiple environmental stressors, as well as integrate the metabolomic and microbiome data to identify how microbial turnover may play a role in coral chemical ecology. For this work, nubbins of Montipora spp. and Oculina patagonica will be collected from the Red Sea and Mediterranean Sea, respectively, and grown under the combined stresses of high temperature, low pH, and high light intensity. Following time for the nubbins to acclimate, indicators of stress and immune responses will be measured. From the remaining fragments, metagenomic and metabolomic analysis will be performed. The data collected will allow the connection of metabolite production to coral health, in addition to the contributions of the microbiome. Furthermore, the data will initiate future research projects, such as linking metabolite production to gene clusters and ascertaining how newly discovered coral metabolites function in terms of coral health. This work will not only further my PhD thesis, but all of coral research.
Umeå University, Sweden
Louisiana State University
Influences of organic matter sources on dissolved inorganic carbon in the carbon budget of a boreal lake system
Most boreal lakes are net heterotophic and thus represent a net source of CO2 to the atmosphere. An estimated 73 Tg of carbon is transferred from these lakes to the atmosphere annually. As temperature and runoff increase with climate change, this amount can be expected to increase. Within a changing climate, northern lakes will experience increased flux of organic and inorganic carbon from surrounding terrestrial sources in both the dissolved and the particulate phase, leading to higherCO2emission. However, existing studies are not clear as to which form of carbon input—dissolved organic carbon, dissolved inorganic carbon, or particulate organic carbon—is the dominant source of CO2 emitted from these lakes. Dissolved inorganic carbon (DIC) represents the CO2, HCO3-, and CO3-2dissolved in an aquatic environment, and is thus a good measurement of CO2that will be emitted into the atmosphere or transported elsewhere. The goal of this study is to carry out ex situ sediment core incubation experiments from two contrasting lakes in boreal Sweden to determine the primary source of DIC production.
Sarah H Burnet
University of Idaho
Assessing the role of sediment-released phosphorus from laboratory incubated cores to their nutrient mass balance collected across a spatial extent in arctic lakes
In many lakes, internal loading of phosphorus (P) from bottom sediments contributes a large fraction to the annual whole-lake P budget and is known to significantly delay improvements of water quality after reducing external sources of P. My objective will be to test the hypothesis that P-release from sediments varies directly with location and headwater characteristics of lakes which influences their thermal stratification, metabolism, and oxygen regimes. Understanding this fraction is crucial to place whole-lake P-budgets in context for i) remediation programs and ii) to predict future changes such as those related to climatic warming. I aim to expand my north temperate data from Willow Creek Reservoir in northeastern Oregon, USA, by collaborating with the Climate Impacts Research Centre (CIRC) associated with Umeå University to measure the sediment P-release rate of laboratory incubated cores collected from a suite of lakes along a latitudinal gradient in the arctic. My research in Oregon shows that the P released from replicate sediment cores collected at six spatially distinct sites varies widely (4.47 to 14.63 mg P/m2/d, even among similarly deep sites), suggesting that rates from multiple sites are needed to derive meaningful measures of internal P loading in lakes and reservoirs. This information can be used by managers to identify ‘hotspots’ to optimize in-lake treatments to reduce sediment-bound P, and by limnologists to predict changes in whole-lake P dynamics and thus the trajectory of lake communities (phytoplankton, zooplankton, nekton, etc.) and their interactions in response to large-scale changes such as those predicted to result from climatic warming.
Sierra E Cagle
Texas A&M University
A numerical model for the investigation of mixotrophic influences on plankton dynamics in warmer, browner boreal lakes
As the climate continues to change, majorly impacting boreal lake systems, it is important to understand how climate driven factors, such as warming and increased colored dissolved organic material (cDOM) will influence the plankton communities of these systems. I hypothesize that in warmer and browner boreal lakes, decreased light from cDOM will lessen the competitive ability of purely autotrophic species, while labile components of the cDOM stimulate the bacterioplankton populations that they compete with for nutrients. And, mixotrophs may be indirectly stimulated by increased cDOM through abiotic interactions between their autotrophic competitors and bacterioplankton prey. To test these hypotheses, I propose a project where a preexisting numerical model that is mechanistically driven and based on a chemostat design is modified to accommodate incorporation of equations governing the dynamics of cDOM concentration, a bacterioplankton population, and a mixotrophic plankton population. Findings from this study may have implications for understanding how biogeochemical cycling and food web structure of boreal lakes will change in the future and contribute to our understanding of how mixotrophy, a common characteristic among harmful and noxious algae, influences these species system invading abilities.
Nicholas A. Castillo
Florida International University
Examining the threat of contaminants to south Florida bonefish: a spatial approach
In South Florida, the recreational fishing industry accounts for a significant economic impact; within this region, the Bonefish fishery is particularly important. This fishery accounts for over half of the $8.0 billion annual revenue from recreational fishing. A decline in the Bonefish stock has been observed over the last decade. This study proposes an assessment of the threat of contaminants on Bonefish. In order to explore the threat of copper and pharmaceuticals to Bonefish, we propose a study utilizing a spatial approach asking how does exposure to key contaminants (copper and pharmaceuticals) vary across South Florida regions? We will analyze the effects of contaminants on a large spatial scale, comparing South Florida to other Caribbean basins, and on a small spatial, analyzing the presence of contaminants in prey relative to distance from shore and contaminant sources. (1) First we propose to conduct a tissue distribution study. The goal is to examine the fate of pharmaceuticals across different tissues (e.g., blood vs. muscle) (2) Second we will examine concentrations of copper and pharmaceuticals in Bonefish prey and a surrogate species in South Florida utilizing multiple transects. Recent studies have discovered elevated levels of copper contaminants in the Biscayne Bay region. In addition to the presence of copper at high enough levels to have potential physiological impacts on the Bonefish population, three previous studies detected the presence of pharmaceutical contaminants in South Florida waters. Previous work has shown that uptake of pharmaceuticals can be tissue-specific, and highlight the need to sample the appropriate tissue in order to assess the true risk of pharmaceuticals to Bonefish. Despite the documented presence of copper and pharmaceutical contaminants in South Florida, and the demonstrated potential for physiological effects on Bonefish, no previous studies have examined this topic; therein resides the justification for the proposed project.
University of Wisconsin - Madison
Factors associated with light availability and the effect on fish production across multiple lake-rich landscapes
Freshwater ecosystems and their fish communities are changing in response to climate, land use, habitat modifications, inputs of nutrients and other chemicals, biotic invasions, harvest, and other large-scale drivers. One of these drivers, water clarity, can greatly affect the productive capacity of fish populations by limiting light availability. Dissolved organic carbon (DOC) inputs result in large-scale variation for northern lakes and overall tend to result in darkened water color. Widespread increases in DOC in northern lakes have been reported and therefore understanding how these changes will affect fish communities is vital to predicting and managing responses to future changes. Although light availability has been established to limit fish biomass and production, the response of fish productive capacity to factors associated with light availability, such as DOC concentration, water color, and nutrient inputs, as well as interactions between these factors, are not well understood. Therefore, I propose a cross-site comparison quantifying spatiotemporal trends in the productive capacity of top consumer fish populations relative to varying factors associated with light availability. I will assess whether within specific lakes, the DOC composition is more closely linked to water color or phytoplankton production (as regulated by total phosphorus (TP)concentration). Within these lakes, I will perform gill net surveys to quantify the productive capacity of top consumers and determine if this varies in relation to factors associated with DOC. Additionally, I will quantify variation in the trophic support pathways (i.e., benthic, pelagic, terrestrial) of fish production between lakes with different light availability drivers. I will test these questions in boreal lakes of Sweden and north temperate lakes of Wisconsin, USA. Further understanding of the interactions of these factors has implications for understanding fish population productivity given varying conditions as well as the trophic pathways that support these communities within the context of a changing climate.
University of New Hampshire
Assessing the influence of N cycling processes on greenhouse gas production in streams using steady state nutrient releases in Abisko, Sweden
Inland waters can be quantitatively significant sources of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) to the atmosphere due to their ability to actively process terrestrial inputs. However, considerable uncertainty remains in regional and global estimates of greenhouse gas emissions from freshwater ecosystems, particularly streams. Controls on greenhouse gas production in fluvial ecosystems, such as the influence of nitrogen (N)cycling processes, are also poorly understood. The main objective of this study is to determine how greenhouse gas flux from streams changes in response to manipulated water chemistry (i.e. increased N concentrations) through a series of steady state nutrient releases in the Miellajökka Catchment within the Abisko Scientific Research Station in Abisko, Sweden. These experiments will improve understanding of how N cycling processes affect greenhouse gas production. Developing an understanding of the factors controlling greenhouse gas production in streams can help assess and predict how fluvial ecosystems will respond to changes in climate and land use. This knowledge can be used to incorporate emissions from streams into regional and global greenhouse gas emission inventories.
University of Cincinnati
Evaluating the role of natural substrate in the nutrient limitation of Arctic biofilms
This project aims to examine how stream substrate size and composition influences the nutrient limitation of Arctic biofilm communities. This research will fill a critical knowledge gap regarding how natural substrate influences nutrient dynamics and allow researchers to accurately assess how Arctic streams will respond to continued environmental change, specifically increased nutrient availability. To elucidate how stream substrate size and composition can influence the nutrient limitation of stream biofilm communities I propose conducting a whole-stream nutrient enrichment study in a natural stream channel over several time points. Arctic stream biofilms have been found to be nitrogen-limited, and I propose to choose a subset of streams (N= 4) from Myrstenerand co-authors (2018) to examine if similar patterns of nitrogen limitation are observed on natural substrates. The distribution of substrate size would be characterized at each site to evaluate the influence of stream substrate size and composition on the nutrient limitation of biofilms. At each timepoint, nutrient uptake, primary production, respiration, and biofilm biomass will be quantified at randomly distributed locations within each reach to evaluate how nutrient limitation changes over time. I hypothesize that sites with smaller substrate will have higher and faster rates of nutrient uptake.
Arizona State University
Influence of vegetation on net ecosystem carbon balance in subarctic mire thaw
Permafrost zones in the subarctic store significant quantities of highly labile carbon. However, recent rising temperatures have resulted in the melting of significant areas of permafrost, making available the underlying, carbon-rich peat. Permafrost thawing has resulted in an increase in CO2 and CH4 emissions; given the vast quantity of carbon these areas store, this phenomenon has significant implications for global atmospheric greenhouse gases concentrations. Melting permafrost results in increased greenhouse gas concentrations and creates a positive feedback loop promoting continually increasing temperatures and increasing permafrost thaw. However, a recent study of thaw ponds in the subarctic Stordalen Mire found that thaw-induced emissions, which significantly offset the carbon sink capacity of the landscape, were reduced in ponds with vegetation (Kuhn et al. 2018). This suggests vegetation may assist in the retention of carbon in these ponds following permafrost thawing. While it is recognized that vegetation can play a pivotal part in carbon emissions, the role of vegetation in carbon balance of thawing permafrost is not well understood. In the proposed research I will explore, how do mire thaw pond primary producer communities influence net ecosystem carbon balance? Particularly, I will investigate how primary producer community composition and functional characteristics of primary producer species influence the net ecosystem carbon balance of permafrost thaw ponds. Given the potential impact of these permafrost regions on global carbon cycling, and the likelihood of greater permafrost thaw in the future as a result of climate change, it is imperative that we understand mechanism influencing the changing carbon cycle regimes in these systems.
Carly Rae Olson
University of Notre Dame
Dynamic modeling of intra- and inter-regional heterogeneity in drivers of lake carbon burial
Lake ecosystems have historically been considered a ‘passive pipe’, where matter from the terrestrial environment simply moves through, ultimately reaching the ocean untransformed. This paradigm has recently been invalidated; lakes are now regarded as biogeochemical hotspots, where terrestrially-derived carbon (C)is transformed and lost, often through burial. Despite this paradigm shift, there is an inadequate, process-level understanding of the drivers regulating lake sediment C burial. In fact, this knowledge gap has led to opposing conclusions regarding the lake sediment C sink among arctic, boreal, and temperate regions. Specifically, allochthonous C dominates C burial in boreal and arctic systems as opposed to autochthonous C in temperate systems. My objective is to reconcile the observed inter-and intra-region heterogeneity in drivers of arctic and temperate lake C burial dynamics. We know that ecosystem processes such as primary production and sediment respiration directly influence the quantity and source of C that is buried. We also know that land cover and lake morphometry indirectly modulate C source through nutrient and oxygen limitation, respectively. To tackle these complex relationships, I will extend a dynamic process model that I have previously developed to explore inter-and intra-regional lake C burial. I will run model simulations across three gradients: catchment nutrients (nitrogen and phosphorus), allochthonous C load, and lake morphometry. I will then compare and contrast the relative importance of primary production, sedimentation, and sediment respiration in C burial across simulated gradients. Data from lakes in the Swedish Arctic provided by Cristian Gudasz at Umeå University and my dissertation in the temperate Midwest of the U.S.A. will be used to assess how well the model predicts patterns of C burial. The model will serve as a unifying framework to explain differences in the observed relationships in lake C burial across regions.
San Francisco State University
Zooplankton growth in northern fishless lakes along a gradient in terrestrial organic matter inputs
In many north temperate and boreal surface waters terrestrial organic matter (tOM) inputs have increased over the past several decades. Increased tOM alters lake ecosystem functions by limiting light and introducing nutrients. It is unclear how increased tOM affects lake productivity and bottom-up control. Copepods are a good species for studying lake productivity because they are the principal trophic link between phytoplankton and fish and therefore very important in food web dynamics. In order to determine how tOM influences lake productivity we propose to measure somatic growth rates of copepods across a gradient of tOM in arctic lakes in northern Sweden. Growth rate is the key rate process in copepod secondary productivity. We will measure growth rates of the dominant calanoid copepod, Eudiaptomus graciloides, using a modified version of the artificial cohort method and an image analysis technique in conjunction with tOM concentration measurements. We will also measure chlorophyll, an indicator of phytoplankton biomass, and relate it to copepod growth rate. As tOM is predicted to increase with climate change, this research will be valuable in helping to better understand the effects of tOM on productivity and how it will affect lake ecosystems.
Breena S Riley
Tarleton State University
Photosynthesis to respiration ratios and diatom assemblages along stream lengths in northern Sweden
Investigators at the Climate Impacts Research Centre (CIRC) of Umeå University seek to understand how carbon cycles through aquatic systems. Determining stream trophic status (heterotrophic versus autotrophic) is a tool which may be used to better understand carbon cycling in streams. To date, no research describes in-stream carbon cycling and trophic status in relation to phytoplankton in northern Sweden. Diatom indices are a well-established technique to determine water quality and to elucidate trophic status. Photosynthesis to respiration (P/R) ratios are also used to determine both qualities. Tools to measure both parameters are readily available at CIRC or may be easily obtained from the student’s home institution. Three types of samples will be collected from each site: diatom samples, isotopic oxygen (18O-DO), and nutrient samples. Diatom samples will be used to determine diatom indices. Isotopic oxygen will measure P/R ratios. Nutrient samples (e.g., nitrogen, phosphorus) will determine water quality. Data collected from each site will be compared within stream sites and across streams locations to determine stream trophic status. It is predicted that streams will change from autotrophic at the headwaters to increasingly heterotrophic further downstream. Data collected from Sweden may potentially be compared to stream conditions in Texas to assess stream trophic status at a broader scale.
Dalhousie University, Canada
The Department of Oceanography
Contact person: ***
Deployment of an in situ porewater sampling system/underwater mass spectrometer in Halifax Harbor and the Bay of Fundy
The importance of permeable marine sediments in global biogeochemical cycling has recently been recognized. These sediments cover the majority of the continental shelves and act as a filter of human nutrient inputs to the coastal ocean. In particular, they are thought to be key sites of denitrification, removing reactive nitrogen from the ocean at greater rates than other marine environments. Accurate measurements in permeable sediments is no trivial task, as mechanisms such as waves and tides drive flows through the interstitial space, influencing the biogeochemistry of their porewater. This porewater advection cannot be replicated by conventional sediment sampling methods. As a result, our knowledge of the magnitude and direction of chemical fluxes in permeable sediments is very limited. To address this, my Ph.D. research is focused on developing a porewater sampler coupled to an underwater mass spectrometer which can make measurements directly in permeable sediments. My proposed research exchange project is to conduct two field deployments in collaboration with Dalhousie University in Nova Scotia with two main objectives: (1) To test my instrument in the field and guide future development, and (2) To obtain some of the first observations ever made in permeable sediment environments. The first deployment will take place in shallow sandy sediments off an island near the mouth of Halifax Harbour over a tidal cycle. Results from this test will be used to develop a denitrification estimate for the harbour. If deployment in this relatively stable environment is successful, a second deployment will be conducted in the Bay of Fundy. We will deploy the instrument at low tide and make measurements as the water depth varies to a maximum of 5 m. This test will provide insights on porewater chemistry under more extreme tidal conditions.
University of South Carolina
Modeling estuarine phytoplankton community responses to inorganic carbon species: simulations with changing carbonic anhydrase activity
Marine phytoplankton exist in an environment characterized with high concentrations of HCO3-and low concentrations of CO2 (aq). Phytoplankton species differ in CO2 requirements and those taxonomic differences in carbon acquisition are exceptionally important when determining the ecological interactions of phytoplankton groups. Variation in the functional trait of dissolved inorganic carbon uptake suggests that there is a capacity for future changes in phytoplankton communities to increasing atmospheric CO2 over the next century. Indirect effects of ocean acidification on productivity and composition of planktonic species may have long-term impacts on trophic interactions between planktonic food sources and higher-level coastal organisms. A collaboration with Dr. Finkel at Dalhousie University would provide the opportunity to answer questions about shifts in marine phytoplankton community structure and productivity due to changes in seawater carbonate chemistry. The main purpose would be to create a sub-model that includes the uptake preferences and carbon acquisition strategies of major estuarine phytoplankton. A focus of the model would be on carbonic anhydrase activity, a component of carbon concentrating mechanisms which actively accumulated inorganic carbon significantly greater than concentrations in the bulk seawater environment. This sub-model could then be integrated into existing ecological models that look at phytoplankton productivity and composition. The model would be parameterized using traits from my own work, the literature, and an experiment conducted in Dr. Finkel’s lab investigating elemental stoichiometry and macromolecular content. The Finkel lab at Dalhousie University is already arranged for those analyses and a further collaboration with Dr. Andrew Irwin in the Math and Statistics department at Dalhousie University makes this project realistic and achievable.
Washington State University Vancouver
Internal wave dynamics, breaking, and mixing in a small eutrophic lake
Internal waves are common in lakes and oceans, where they can mix and transport heat, nutrients, and pollutants, with possible consequences for sediment transport, biogeochemistry and ecology. Using high-resolution observations of temperature and velocity, we propose to examine the dynamics of internal waves propagating and breaking above a sloping lakebed. Observations reveal a remarkable variety of internal wave forms within just 1 m of the lakebed. We identify four different wave forms: intensely breaking bores, undular bores, solitons, and non-breaking cold fronts. Observations of near-bed currents and wave propagation speeds, as well as “offshore” wave amplitudes, will be used to identify the factors controlling wave form. Propagation speeds will be compared with simple linear theories for waves reflecting from a sloping bed. Finally, estimated turbulent energy dissipation rates and buoyancy fluxes will be compared across the different waveforms during both upslope and downslope flow, to evaluate the importance of internal waves to boundary layer mixing.
Scripps Institution of Oceanography
Integration of prototype sensors into the SeaCycler profiling mooring
The net flux of carbon dioxide (CO2) gas into the global ocean, driven biologically by net community production (NCP) and by physical forcing, helps to reduce the effects of climate change by removing CO2from the atmosphere. Currently, assumptions need to be made to constrain the air-sea gas fluxes and NCP with in-situ measurements because available sensor technology cannot observe all quantities necessary to close these mix layer budgets. With recent developments in sensor technology, a combination of sensors, some still in prototype form, when integrated into a moored profiling platform (the SeaCycler) simultaneously determine NCP and the air-sea flux of CO2. Deployment to test the SeaCycler and the integrated prototype sensors in the Labrador Sea (LS), an area of particular importance to global carbon budget uncertainties, is the culmination of multiple NSF funded projects and collaboration between Dalhousie University (Dal) and the Scripps Institution of Oceanography (SIO). Included in the deployment testing is the integration of two of the prototype sensors, the self-calibrating SeapHOx, and the in-situ dissolved inorganic carbon (DIC) sensor, both developed in the Martz lab of which I am a member. In preparation for this deployment, if I am a recipient of the LOREX, I would work to integrate both prototype sensors into the SeaCycler system at Dal.
Florida International University
Phytoplankton and detritus biomass estimates in the mesopelagic Gulf of Mexico as a function of seasonality
The Gulf of Mexico is an oceanic region of economic importance because of human activities, such as: commercial fisheries and oil exploitation. The fishes and squids of the mesopelagic zone (200 –1000-m depth) are prey to commercially important consumers (e.g., tuna and billfishes). The 2010 Deepwater Horizon oil spill (DWHOS) threatened the biota of the mesopelagic ecosystem, as well as the epipelagic and neritic zones. The area seaward of the DWHOS site has been sampled intensely through trawl surveys over the past eight years, improving our understanding of the organisms that live from the surface to 1500-m depth. Much of these data have been centered on higher trophic levels (e.g., macrozooplankton and micronekton). However, data for the lower trophic levels (i.e., phytoplankton and detritus estimates) are scarce. Phytoplankton and detritus estimates that do exist for the oceanic Gulf of Mexico do not often account for seasonality. However, the proximity of the Mississippi River to the most intensely studied region after the DWHOS suggests that nutrient concentrations and the subsequent primary productivity of the region change on a seasonal basis. Through a collaboration with Dr. Katja Fennel and Dalhousie University three objectives will be examined: 1) the phytoplankton biomass will be estimated for the oceanic northern Gulf of Mexico seaward of the DWHOS site on a seasonal basis, 2) with these phytoplankton estimates, the detritus stock of the top 1000 m within our study site will be estimated, and 3) phytoplankton and detritus stocks will be assimilated into a mass-balanced ecosystem model that is currently being developed for the mesopelagic Gulf of Mexico.
Southern Cross University, Australia
National Marine Science Centre at Coffs Harbor
Contact person: ***
University of Hawaiʻi at Mānoa
Unravelling wastewater leakages to coastal waters under future sea levels
Sea level rise (SLR) is currently impacting coastal infrastructures worldwide during tidally-driven nuisance flooding. Many of the world’s largest and densest cities are located on coastline sand have aging wastewater infrastructure that were designed overlooking SLR. Sydney Harbour, Australia suffers from wastewater pollution, and submarine groundwater discharge (SGD)has not yet been investigated as a mechanism for wastewater delivery to the bay. Wastewater is enriched in organic matter and a number of pollutants. Wastewater leakages to groundwater may eventually reach surface waters, promoting pollution, but this has not previously been directly investigated. I propose to study wastewater-enriched SGD using a combination of pharmaceuticals, naturally occurring groundwater tracers (radon and radium), greenhouse gases (GHGs), and stable isotopes (δ15N-NO3-and δ15N-N2O). The field portion of the study will be conducted in two phases during high spring tides as a proxy for future sea levels: (1) an initial radon, GHG, and pharmaceutical survey to map locations of SGD and wastewater discharge, and (2) radon and GHG time-series at three locations determined to have wastewater input and three baseline control locations. These locations will also be sampled for pharmaceuticals, radium, nutrients, and δ15N-NO3-and δ15N-N2Oat low and high tide. This study will result in differentiation between wastewater-enriched SGD and “baseline” SGD-derived wastewater in Sydney Harbour. This study is important because it addresses SLR-driven wastewater and SGD fluxes and would be the first to illuminate the mechanism of tidally-driven wastewater-enriched SGD-derived pollution. The methodology used in this study ideally will be used as a model for projecting future impacts of SLR on wastewater infrastructure of coastal communities worldwide.
Southern Cross University, Australia
Southern Cross University at Lismore
Contact person: ***
University of Washington
Physical impacts of mangrove removal: re-evaluation of sediment characteristics and transport on intertidal surfaces >10-years after mangrove removal in Tauranga Harbor, New Zealand
Low-lying coastal regions throughout the world are densely populated, economically valuable, and vulnerable to sea-level rise and natural disasters. Mangrove forests increase the resilience of tropical coastlines to erosion or inundation by retaining sediment and damping waves. There is a pressing need to understand how landforms will change as mangrove forests are removed for agricultural expansion. However, it is often challenging to collect field measurements to quantify sediment transport and deposition in mangroves, especially over multiple years. A mangrove removal project in the Waikaraka Estuary of Tauranga Harbor, New Zealand has provided an opportunity to study decadal-scale changes associated with deforestation. Beginning in 2005, mangroves were removed to reduce fine sediment retention in the harbor. The sediment dynamics were assessed in forested, cleared, and naturally unvegetated tidal surfaces of the estuary during the removal period. Initially, fine sediment was flushed out of the cleared region, but tidal flats were still predominantly muddy. The same measurements will be collected now, >10 years after removal. The character and organic content of sediment will be assesed in subsampled, 1-m cores. Sediment traps will be deployed to measure the composition of transported sediment, and deposition rates will be measured using horizon markers. It is hypothesized that continued mangrove root decomposition and storm activity would have removed fine material, resulting in an overall coarsening of tidal surfaces. These field measurements will provide validation and constraints for models of coastal change associated with mangrove removal. This project will simultaneously aid in developing skills and relationships which will be leveraged for future international research. Many vulnerable coastal regions are located in developing or politically turbulent countries with limited access to scientific resources. Collaboration and scientific exchange will be critical for keeping pace with the many challenges that sea-level rise will bring.
University of Massachusetts
Nitrogen stable isotopes in Australian Utricularia as an early indicator of eutrophication.
The genus Utricularia is a carnivorous plant that occurs in nutrient-poor wetlands. This genus of carnivorous plants uses bladders to trap and digest small invertebrates as a source of nitrogen to compensate the lack of nutrients in its habitats. There are currently59 known Australian species which comprises ~25% of the world population. Utriculariain Australia are of particular importance, because as much as 75% of the native species are strictly endemic,and form their own phylogenetic clade. Unfortunately, due to the introduction of excess nitrogen and other nutrients from livestock farming and crop fertilizers, these plants and their fragile habitats are disappearing fast. However, it is unclear exactly how such nutrient enrichment will affect how the plants themselves process nutrients. This is a critical research gap because Utricularia may depend primarily on carnivory under ‘pristine’ water conditions, but are known to drop their trap sand switch to photosynthetic energy when the water quality declines. I hypothesize that they may shift their nutrient intake from prey to the environment. I therefore propose that Utricularia could be used as an early indicator for eutrophication by measuring shifts in their isotopic composition (del15N values). The proposed collaboration with the Centre for Coastal Biogeochemistry, NSW, Australia will enable me to master these isotopic techniques and apply them to Australian native Utricularia in waterways with varying degrees of eutrophications. The outcome of this collaboration will form the foundation for future research into Utricularia specifically and Australian wetland habitat degradation more broadly.
Florida Agricultural and Mechanical University (FAMU)
Implementation of the foram index in coral larvae relocation sites at Philippines’ Islands
In the Philippines’ Islands, more than the 90% of coral reef ecosystems have been negatively affected mainly by anthropogenic inputs (e.g., overfishing and blast fishing). Agencies had to declare a "reef degradation" status in the archipelago. Hence, a better understanding of the health of the reefs from the Philippines’ Islands is a priority for improving stakeholders' decisions in support to resources managers for proper management actions. Given that, the settlement of coral’s larvae has been occurring and resulting in a positive management methodology to proliferate corals growth in degraded reefs. However, a monitor tool that can evaluate the settings conditions, and suggest the further coral development is necessary. For this reason, the application of ecological indexes such as the FORAM Index (FI) as a bioindicator tool can address the reef conditions. FI has been applied worldwide (e.g., Caribbean, Australia, and the Mediterranean). The FI is a method used to determine the water quality of the reef's surroundings using foraminifers as indicators; FI values will reflect the actual reef conditions and will suggest further development in the ecosystem. In our experiment, we will assess the larvae relocation areas from the Philippines Islands using the FI as an indicator tool and determine water quality parameters(e.g., pH, DO, PO4, chlorophyll-a). Methodologically, the locations were experimental larval relocation in the Bolinao-Anda Reefs Complex will be sampled. At each station water and sediment samples will be collected to measure the variables mentioned before. Our results will measure the effectiveness of the FI, determine which water quality parameters(s) are or could affect the coral survivorship, identify current reef conditions; and will contribute to resources managers with a rapid and cost-effective biomonitoring tool to improve management efforts.
Texas A&M University
Comparing active microbial communities in mangrove sediments
Mangrove wetlands can store carbon that can be transformed into methane and other greenhouse gasses. Microbial communities are susceptible to shifts due to climate change; largely driving the carbon cycle within the sediment. An increase in seasonal rain, droughts, and warming winters can alter the vegetation distribution, and structure of the coastline; therefore, cause the microbial community structure and function to adapt in response. Shifts in microbial activity and abundance will subsequently cause geochemical cycles to fluctuate. It is vital to understand how microbes impact geochemical cycling in mangrove sediments in order to understand how this will impact changing coastlines. This project will investigate changing microbial communities with respect to geochemical cycles by collecting sediment for the following analyses: A) RNA/DNA extractions that will identify the active and total microbial community, respectively; B) methane headspace analyses to identify the flux of methane from the sediment column; and C) porewater analyses using colorimetric methods to investigate biogeochemical cycles in context of the carbon cycle. These three analyses will be useful for investigating the metabolisms of the active microbial communities and their relation to gas emissions. This project aims to compare mangrove systems in the southern atmosphere to previously sampled systems in the northern hemisphere. Statistical analyses of all data will be conducted to compare changes in geochemistry and the microbial community structure. Alpha, Beta, and Gamma diversity analyses for microbial communities will be determined. Links will be made between community structure and rate measurements using multivariate analyses (e.g., singular value decomposition, ANOVA). By understanding what drives microbial function, and therefore methane emissions, future predictions can be made regarding methane flux in mangrove ecosystems.
The effects of increased temperature on the feeding rates of coral reefs in the presence of high DMSP phytoplankton
As a consequence of climate change, coral bleaching has become widespread. Specifically increases in temperature have been shown to lead to the breakdown of symbiosis between corals and their symbionts. Within a healthy coral, Dimethylsulfuloniopropionate (DMSP) is produced and thought to have roles in coral thermoregulation, chemoattraction, osmoregulation, and antioxidant response. DMSP has also been found in macroalgae as a predation deterrent against microzooplankton, mainly protists. These findings raise questions about the effect that both climate change, specifically elevated temperatures, and high DMSP in macroalgae may be having on the effectiveness of coral feeding on this macroalgae. To gain a better understanding of coral feeding rates on phytoplankton with high DMSP and elevated temperature, a series of coral tanks will be set up to manipulate temperature and the presence or absence of high DMSP with phytoplankton. These experiments will be used to test the hypotheses that 1) high DMSP in phytoplankton will lead to low feeding rates of coral and 2) the addition of elevated temperature and high DMSP will lead to lower feeding rates of coral. The results of this study will help to better inform the ways in which climate change may be negatively affecting coral reef communities globally.
Inter University Institute for Marine Science in Eilat, Israel
Ashley Brooke Cohen
Stony Brook University
Aeolian reactive metal-driven microbial elemental sulfur disproportionation in low organic carbon sediment
Microbially-mediated elemental sulfur (S0) disproportionation significantly affects the stable isotope relative abundances in and the production of sulfate (SO4-2) and sulfide (S-2). However, this reaction is only energetically favorable under anoxic conditions when there is enough reactive iron or manganese to “scrub”S-2. For modern global geochemical mass balances or budgets, this phenomenon is thought to be restricted to permanently stratified water columns or coastal sediment with high fluxes of organic carbon (OC), and therefore is not considered significant. However, recent work by Blonder et al. (2017) on low-OC sediment underlying relatively deep water in the Gulf of Aqabaraises the possibility that high fluxes of aeolian reactive iron and manganese can fuel microbial S0disproportionation in a more widespread marine environment. To determine the impact of S0disproportionation on the production and consumption of sulfur species, microbial C production, and sulfur stable isotope signatures, it is critical to take in-situ rate measurements, as products and reactants may be turned over so rapidly that they are not detectable by chemical profiling. I propose an in-situ incubation study that will simultaneously: determine sulfur species and reactive metal concentration rate measurements, which reactive metal (if any) better promotes S0 disproportionation by serving as a S-2sink, and link the S0disproportionation reaction stoichiometry determined through those rate measurements to changes in sulfur stable isotope signatures of S0, S-2, and SO4-2. To calculate biovolumes and ultimately how much biomass carbon is being produced per mole S0, disproportionate r cells will be fluorescently labelled with a probe specific to their 16S rRNA; the probe will be designed through Stable-Isotope-ProbingDNA.
University of California, Santa Barbara
Compound-specific stable isotope analysis to enhance in situ coral monitoring
Reef-building corals meet nutritional needs by fixed organic carbon from their photosynthetic endosymbionts Symbiodinium and heterotrophic feeding on particles, zooplankton and dissolved organic carbon in the water column. While a great deal of coral research has focused on the symbiosis, the importance of coral feeding in supplying carbon and nutrients (nitrogen and phosphorus) to the holobiont has become increasingly clear. Feeding acts as a mechanism for nutrient and carbon supply for biomass growth and reproduction and may become necessary for survival under “non-normal” conditions such as low-light, eutrophication, and elevated water temperatures that cause bleaching. Yet detailed metabolic feeding studies are often restricted to the laboratory, and in situ monitoring measurements are typically too coarse to discern key physiological processes that occur in changing environments. Here I propose the development of compound-specific isotope analysis (CSIA) of amino acids for in situ coral monitoring.The15N/14N and 13C/12C ratios within essential and non-essential amino acids in one coral tissue sample can provide information on the source of the nitrogen and carbon the feeding strategy of the coral (% of biomass nitrogen and carbon heterotrophically acquired),and detailed resource allocation within the symbiosis. I propose to develop this low-effort sampling for long-term monitoring by ground-truthing the CSIA measurements with parallel bulk-tissue isotope measurements of the coral animal, Symbiodinium and community food web endmembers to supply source isotope signatures. CSIA and bulk-tissue analysis will be done for several coral species (roughly one per morphology type) across an environmental gradient and in parallel with “typical” coral monitoring measurements to uncover patterns between “typical” measurements and results from CSIA analysis across taxa and environmental gradients. Additionally, I plan to develop and disseminate this method for broad utilization by the National Science Foundation Long Term Ecological Research Network.
University of Haifa, Israel
Using models, experiments and field work to map metabolic interactions in synthetic and natural marine bacterial ecosystems
Microbial communities catalyze biogeochemical cycles across Earth’s compartments and perform crucial ecosystem functions impacting all forms of life. The power of communities to influence global-level processes derives from the collective action of individual species; therefore, to understand the effects of communities, we need to understand how bacteria interact within them. Predicting microbial community behavior based on the identity and relative abundance of species present is one of the outstanding challenges in microbial ecology, especially for highly complex, dynamic ecosystems. The overarching goal of this project is to systematically predict cross-feeding interactions between marine heterotrophic bacteria based on their genome sequences, testing these predictions in laboratory co-cultures and in the ocean. My current work in the Segrè lab is focused on using metabolic network reconstructions to bridge the gap between genomics and microbial community function. To this end, I use genome-scale computational models in concert with systematic laboratory experiments to predict the nutritional requirements and metabolites produced by a diverse set of heterotrophic marine bacteria, and whether these features can predict syntrophic relationships between different species. The goal of this LOREX project is to move beyond the laboratory, and test our ability to resolve metabolic interactions in natural marine microbial communities using a combination of field observations and bottle incubation experiments involving marine samples from the Eastern Mediterranean. Only through a “cross-scale” understanding that unites modeling approaches with oceanography might we be able to anticipate how microbial populations respond to changing environments and how they affect major biogeochemical processes in a rapidly evolving world.