LOREX Projects

LOREX: Participants and Projects

Principal Investigators

Dr. Adina Paytan
Research Professor, Institute of Marine Sciences
University of California, Santa Cruz
Email: apaytan@ucsc.edu
Dr. Adrienne J. Sponberg
ASLO Director of Communications and Science
Email: asponberg@aslo.org
Dr. Michael Pace
ASLO President
Email: president@aslo.org
Dr. Linda Duguay
ASLO Past-President
Email: past-president@aslo.org

LOREX and Science Communication interns


Brittany Schieler – Summer 2019 LOREX and ASLO Science Communication Intern

Brittany is a marine microbiologist and phytoplankton ecologist who recently graduated with a Ph.D. in oceanography from Rutgers University. Her research focused on an important species of phytoplankton called Emiliania huxleyi that produces beautiful and intricate shells of calcium carbonate (the same stuff coral reefs are made of!). Brittany studied how the production of free radicals impacts the susceptibility of E. huxleyi to infection by viruses.

During her Ph.D., Brittany participated in several field campaigns that took her all over the world and involved collaborators from various international institutions. As an ASLO Science Communication Intern, Brittany plans to foster her interests in collaboration by assisting with ASLO’s inaugural Limnology and Oceanography Research Exchange (LOREX) program. During the internship, Brittany also hopes to gain useful insights into the management of science non-profits as well as develop tools to engage the public and policy-makers on the importance of the hidden microbial world to the health of our oceans. . If you need any support, please feel free to contact us at communications@aslo.org.


Maha Cziesielski – Fall 2019 LOREX and ASLO Science Communication Intern

Maha Cziesielski is a PhD student at the King Abdullah University of Science and Technology in Saudi Arabia, where she studies the impacts of climate change on coral’s molecular machinery. Her thesis focuses on multiple layers of cell functions, namely transcriptomics, proteomics and epigenomics, to understand coral-algae symbiosis and factors that determine thermotolerance. Besides conducting research she is also passionate about science communication, outreach and education. Since starting to write in 2017, she has contributed to numerous blogs and is currently one of the editors in chief at Reefbites. Maha will be serving as a Science Communication Fellow for the Association for the Sciences of Limnology and Oceanography in Washington D.C. starting in September 2019.

Umeå University, Sweden

Climate Impacts Research Centre
Contact person: Dr. David Seekell, david.seekell@umu.se


Hannah Beck
Louisiana State University

Influences of organic matter sources on dissolved inorganic carbon in the carbon budget of a boreal lake systemMost boreal lakes are net heterotopic and thus represent a net source of CO2tothe 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 outex 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 lakesIn 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 artic. 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 lakesAs the climate continues to change, majorly impacting boreal lake systems, itis 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 approachIn 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.


Holly Embke
University of Wisconsin - Madison

Factors associated with light availability and the effect on fish production across multiple lake-rich landscapesFreshwater 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.


Allison Herreid
University of New Hampshire

Assessing the influence of N cycling processes on greenhouse gas production in streams using steady state nutrient releases in Abisko, SwedenInland 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.


Chelsea Hintz
University of Cincinnati

Evaluating the role of natural substrate in the nutrient limitation of Arctic biofilmsThis 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.


Marina Lauck
Arizona State University

Influence of vegetation on net ecosystem carbon balance in subarctic mire thawPermafrost 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 burialLake 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.


Stephanie Owens
San Francisco State University

Zooplankton growth in northern fishless lakes along a gradient in terrestrial organic matter inputsIn 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 SwedenInvestigators 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.


Garrett Rue
University of Colorado Boulder

Sentinels of Change: seasonality and sensitivity of lacustrine environments to disturbance effectsThrough the study of watersheds experiencing different levels of climate-driven disturbances, my dissertation explores their dynamic effect on carbon cycling, trophodynamics, and aquatic ecosystem structure. The final phase of this research expands to a larger scale within the landscape continuum, where lakes play an important, holistic role of integrating catchment response. In oligotrophic environments, such as those in arctic and alpine regions, lakes are sensitive hydrologic features where physical drivers, biota, and biogeochemical processes mediate ecosystem structure and function. The collaborative research proposed for the LOREX Program follows a 2018 winter limnology study focused on a sub-alpine lake, to include observations of the rapid period of change during spring-summer transition in an analogous arctic region, where ice cover also dominates. Building off the hypotheses from Hood et al. (2003) and the reactive transport model developed by Miller et al. (2009), this research combines these conceptual frameworks with data through which to elucidate dissolved organic matter (DOM) production and transformation. By integrating seasonal lake studies, we may clarify the competing role of physical drivers such as light availability and landscape connectivity, to biogeochemical factors such as DOM quality as well as nutrient cycling, against phenological response of autotrophic and heterotrophic communities. The FT-ICRMS analysis of samples collected during the winter experiment revealed interesting patterns of biological activity and molecular incorporation of phosphorus into the DOM pool, suggesting an evolving pool of labile carbon under ice-cover. In support of these findings, I seek to visit the Abisko Scientific Research Station to collect observations during seasonal change to quantify these shifts in lake carbon cycling to bolster this predictive model beyond the existing scope to capture critical transition periods for sensitive regions on which limited datasets exist.

Dalhousie University, Canada

The Department of Oceanography
Contact person: ***


Emily Chua
Boston University
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.


Eilea Knotts
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 CO2requirementsand 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.


Jeffrey Nielson
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.


Wiley Wolfe
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.


Matthew Woodstock
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: ***


Trista McKenzie
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: ***


Hannah Glover
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.


Emmi Kurosawa
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.


Angelique Rosa-Marin
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.


Rachel Weisend
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.


Keiko Wilkins
Miami University
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

Eilat, Israel
Contact person: Simon Berkowicz, simonb@mail.huji.ac.il


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 S0disproportionationby 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.


Connor Love
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/14Nand 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

The Leon H. Charney School of Marine Sciences, Haifa
Contact person: Ilana Berman-Frank, iberman2@univ.haifa.ac.il


Elena Forchielli
Boston University
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.

Recent LOREX Articles

Scroll to Top