|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.