62 research outputs found
Rapid Regeneration of the Body Wall of the Aboral Central Disc in the Sea Star Luidia clathrata
Seawater acidification more than warming presents a challenge for two Antarctic macroalgal-associated amphipods
Elevated atmospheric pCO2 concentrations are triggering seawater pH reductions and seawater temperature increases along the western Antarctic Peninsula (WAP). These factors in combination have the potential to influence organisms in an antagonistic, additive, or synergistic manner. The amphipods Gondogeneia antarctica and Paradexamine fissicauda represent prominent members of macroalgal-associated mesograzer assemblages of the WAP. Our primary objective was to investigate amphipod behavioral and physiological responses to reduced seawater pH and elevated temperature to evaluate potential cascading ecological impacts. For 90 d, amphipods were exposed to combinations of seawater conditions based on present ambient (pH 8.0, 1.5°C) and predicted end-of-century conditions (pH 7.6, 3.5°C). We recorded survival, molt frequency, and macroalgal consumption rates as well as change in wet mass and proximate body composition (protein and lipid). Survival for both species declined significantly at reduced pH and co-varied with molt frequency. Consumption rates in G. antarctica were significantly higher at reduced pH and there was an additive pH-temperature effect on consumption rates in P. fissicauda. Body mass was reduced for G. antarctica at elevated temperature, but there was no significant effect of pH or temperature on body mass in P. fissicauda. Exposure to the pH or temperature levels tested did not induce significant changes in whole body biochemical composition of G. antarctica, but exposure to elevated temperature resulted in a significant increase in whole body protein content of P. fissicauda. Our study indicates that while elevated temperature causes sub-lethal impacts on both species of amphipods, reduced pH causes significant mortality
Eelgrass pathogen Labyrinthula zosterae synthesizes essential fatty acids
Negative consequences of parasites and disease on hosts are usually better understood than their multifaceted ecosystem effects. The pathogen Labyrinthula zosterae (Lz) causes
eelgrass wasting disease but has relatives that produce large quantities of nutritionally valuable
long-chain polyunsaturated fatty acids (LCPUFA) such as docosahexaenoic acid (DHA). Here we
quantify the fatty acids (FA) of Lz cultured on artificial media, eelgrass-based media, and eelgrass
segments to investigate whether Lz may similarly produce LCPUFA. We also assess whether fieldcollected lesions show similar FA patterns to laboratory-inoculated eelgrass. We find that Lz produces DHA as its dominant FA along with other essential FA on both artificial and eelgrass-based
media. DHA content was greater in both laboratory-inoculated and field-collected diseased eelgrass relative to their respective controls. If Lz’s production scales in situ, it may present an unrecognized source of LCPUFA in eelgrass ecosystems.We thank the staff of the South Slough
National Estuarine Research Reserve, Zofia Knorek, Nicole
Nakata, Isaiah-Peacott Ricardos, and Alexa Romersa for
field and laboratory assistance. We also thank Morgan
Eisenlord for fantastic discussion on this subject and manuscript. We thank the 3 anonymous reviewers for constructive
comments and suggestions, substantially improving our
manuscript. This material is based on work supported by the
National Science Foundation Graduate Research Fellowship
under Grant No. 1309047. A.W.E.G. and J.B.S. were supported by startup funds granted to A.W.E.G. by the University of Oregon.Ye
Trophic Transfer of Macroalgal Fatty Acids in Two Urchin Species: Digestion, Egestion, and Tissue Building
Sea urchins are ecosystem engineers of nearshore benthic communities because of their influence on the abundance and distribution of macroalgal species. Urchins are notoriously inefficient in assimilation of their macroalgal diets, so their fecal production can provide a nutritional subsidy to benthic consumers that cannot capture and handle large macroalgae. We studied the assimilation of macroalgal diets by urchins by analyzing the profiles of trophic biomarkers such as fatty acids (FAs). We tracked macroalgal diet assimilation in both Strongylocentrotus droebachiensis and S. purpuratus. Juvenile S. droebachiensis and adult S. purpuratus were maintained for 180 and 70 days, respectively, on one of three monoculture diets from three algal phyla: Nereocystis luetkeana, Pyropia sp., or Ulva sp. We then analyzed FA profiles of the macroalgal tissue fed to urchins as well as urchin gonad, gut, digesta, and egesta (feces) to directly evaluate trophic modification and compare nutritional quality of urchin food sources, urchin tissues, and fecal subsidies. In the S. purpuratus assay, there were significantly more total lipids in the digesta and egesta than in the algae consumed. The FA profiles of urchin tissues differed among urchin species, all diets, and tissue types. Despite these differences, we observed similar patterns in the relationships between the urchin and macroalgal tissues for both species. Egesta produced by urchins fed each of the three diets were depleted with respect to the concentration of important long chain polyunsaturated fatty acids (LCPUFAs), but did not differ significantly from the source alga consumed. Both urchin species were shown to synthesize and selectively retain both the precursor and resulting LCPUFAs involved in the synthesis of the LCPUFAs 20:4ω6 and 20:5ω3. S. droebachiensis and S. purpuratus exhibited consistent patterns in the respective depletion and retention of precursor FAs and resulting LCPUFAs of Pyropia and Ulva tissues, suggesting species level control of macroalgal digestion or differential tissue processing by gut microbiota. For both S. droebachiensis and S. purpuratus, macroalgal diet was a surprisingly strong driver of urchin tissue fatty acids; this indicates the potential of fatty acids for future quantitative trophic estimates of urchin assimilation of algal phyla in natural settings
Sea otter effects on trophic structure of seagrass communities in southeast Alaska
Previous research in southeast Alaska on the effects of sea otters Enhydra lutris in
seagrass Zostera marina communities identified many but not all of the trophic relationships that
were predicted by a sea otter-mediated trophic cascade. To further resolve these trophic connections, we compared biomass, carbon (δ13C) and nitrogen (δ15N) stable isotope (SI), and fatty acid
(FA) data from 16 taxa at 3 sites with high and 3 sites with low sea otter density (8.2 and 0.1 sea
otters km−2, respectively). We found lower crab and clam biomass in the high sea otter region but
did not detect a difference in biomass of other seagrass community taxa or the overall community
isotopic niche space between sea otter regions. Only staghorn sculpin differed in δ13C between
regions, and Fucus, sugar kelp, butter clams, dock shrimp, and shiner perch differed in δ15N. FA
analysis indicated multivariate dissimilarity in 11 of the 15 conspecifics between sea otter regions.
FA analysis found essential FAs, which consumers must obtain from their diet, including 20:5ω3
(EPA) and 22:6ω3 (DHA), were common in discriminating conspecifics between sea otter regions,
suggesting differences in consumer diets. Further FA analysis indicated that many consumers rely
on diverse diets, regardless of sea otter region, potentially buffering these consumers from sea
otter-mediated changes to diet availability. While sea otters are major consumers in this system,
further studies are needed to understand the mechanisms responsible for the differences in biomarkers between regions with and without sea ottersWe thank Tiffany Stephens, Maggie
Shields, Melanie Borup, Ashely Bolwerk, Nicole LaRoche,
Tom Bell, Michael Stekoll and the rest of the Apex Predators, Ecosystems and Community Sustainability (APECS)
team and 26 Earthwatch volunteers for assistance in the
field and laboratory. Special thanks to Reyn Yoshioka,
Natalie Thompson, the Coastal Trophic Ecology Lab, and
Oregon Institute of Marine Biology for their assistance with
fatty acid extractions, Melissa Rhodes-Reese at University of
Alaska Southeast for water nutrient analysis, and Matthew
Rogers and NOAA Auke Bay Laboratories for assistance
with stable isotope analyses. This study was funded by the
National Science Foundation (NSF #1635716, #1600230 to
G.L.E.), through the generous support of Earthwatch, and a
56 NSF Graduate Research Fellowship, a North Pacific Re -
search Board Graduate Student Research Award, an American Fisheries Society Steven Berkeley Marine Conservation
Fellowship, and a Lerner Gray Memorial Fund (to W.W.R).
This study was completed in partial fulfillment of the
requirements for W.W.R.’s PhD at the University of Alaska
Fairbanks and we thank committee members Dr. Franz
Mueter and Dr. Anne Beaudreau for their comments on this
project and the manuscript. Finally, we thank the 3 anonymous reviewers whose comments greatly improved the
manuscript. This study was conducted on the traditional
lands and waters of the Alaska Native Tlingit and Haida
peoples. We are grateful for our access to these spaces and
benefited from conversations and support from the members
of Tribal communities and governments.Ye
Ocean warming and acidification alter Antarctic macroalgal biochemical composition but not amphipod grazer feeding preferences
Increased anthropogenic atmospheric CO2 concentrations have resulted in ocean
warming and alterations in ocean carbonate chemistry, decreasing seawater pH (ocean acidification). The combination of ocean warming and acidification (OWA) may alter trophic interactions
in marine benthic communities along the western Antarctic Peninsula (WAP). Abundant and diverse
macroalgae–grazer assemblages, dominated by macroalgae (e.g. chemically defended Desmarestia anceps and D. menziesii) and gammarid amphipods (e.g. Gondogeneia antarctica), occur on
the nearshore benthos along the WAP. In the present study, the amphipod G. antarctica and
macroalgae D. anceps and D. menziesii were exposed for 39 and 79 d, respectively, to combinations of current and predicted near-future temperature (1.5 and 3.5°C, respectively) and pH (8.0
and 7.6, respectively). Protein and lipid levels of macroalgal tissues were quantified, and 5-way
choice amphipod feeding assays were performed with lyophilized macroalgal tissues collected at
time zero and following exposure to the 4 temperature-pH treatments. For D. anceps, we found a
significant interactive temperature-pH effect on lipid levels and significantly lower protein levels
at reduced pH. In contrast, tissues of D. menziesii exhibited significantly greater lipid levels after
exposure to reduced pH, but there was no temperature effect on lipid or protein levels. Despite
shifts in macroalgal biochemical composition, there were no changes in amphipod feeding preferences. Our results indicate that despite altered macroalgal nutritional quality under OWA, both
macroalgae retained their ability to deter amphipod feeding. This deterrent capacity could
become an important contributor to net community resistance of macroalgae−mesograzer assemblages of the WAP to predicted OWA.The authors gratefully acknowledge
the exemplary logistical and science support of the staff of
Antarctic Support Contract. Margaret Amsler and Kevin
Scriber of the Department of Biology at UAB provided valuable field assistance, and Charles Katholi of the UAB
Department of Biostatistics provided invaluable statistics
consultation. Additional thanks are due to Kenan Matterson
for his assistance with protein assays and Robert Thacker for
access to his laboratory equipment. The present study was
supported by NSF award ANT-041022 (J.B.M., C.D.A.,
R.A.A.) from the Antarctic Organisms and Ecosystems program. J.B.M. acknowledges support from an Endowed Professorship in Polar and Marine Biology from UAB.Ye
Juvenile Dungeness crab foraging behavior and lipid composition is altered more by food quantity than seawater pH in a multi-stressor experiment
Increases in atmospheric, anthropogenic carbon are driving reductions in seawater pH, a process referred to as ocean acidification. Reduced seawater pH can influence behavior of marine animals, but little is currently known about how juvenile crustaceans will respond. We conducted lab experiments to improve our understanding of the consequences of pH exposure and food quantity on juvenile Dungeness crab (Metacarcinus magister, (Dana, 1852)) behavior and nutritional condition. To understand the foraging and pH sensing behavior of juvenile crab, and how this interacts with their nutritional status, we exposed recently settled second instar juveniles to either ambient pH or reduced pH for 42-d, crossed with either a ‘maintenance’- or low-quantity ‘challenge’ diet treatment. After the experimental exposure period, we introduced crab into foraging and sensing pH behavior experiments. In the foraging experiment, we placed crab in a behavior arena with unidirectional flow, where we measured the food discovery time and time allocation of activities in 300-s trials for all individual crab. Food quantity and pH exposure influenced both the speed with which juvenile crab identified and allocation of activities but there was no interactive effect of experimental factors. For our pH sensing experiment, we used a two-current flume plumbed with both ambient and reduced pH seawater. This flow-through flume provided a choice between the pH treatment waters and allowed us to measure the amount of time individuals spent on either side of the arena in 300-s trials. There was no effect of prior diet or pH exposure on the amount of time juvenile crab spent in either seawater pH condition. In addition to the behavior trials, we evaluated crab nutritional condition by quantifying the total lipid content of whole-body tissues and fatty acid profile composition of juvenile crab fed either the maintenance or low-quantity diet during the experimental pH exposure period. The proportional fatty acid profiles differed for crab based on their diet and pH exposure, with no interactive effects. However, we did not detect differences in the concentrations of key summary categories of fatty acids (e.g., saturated, monounsaturated, or polyunsaturated) based on pH exposure. Our results indicate that reduced food availability has a greater impact on juvenile Dungeness crab foraging behavior and nutritional condition than reduced seawater pH exposure representing the 0.3 pH unit decrease predicted by 2100.National Oceanic and Atmospheric Administration's National Sea Grant College Program.
National Science Foundation.
US Department of Commerce.
Oregon State Legislature.
M. J. Murdock Trust Partners-in-Science.Highlights -- Abstract -- Keywords -- 1. Introduction -- 2. Materials and methods -- 3. Results -- 4. Discussion -- CRediT authorship contribution statement -- Declaration of Competing Interest -- Acknowledgements -- Appendix A. Supplementary data -- Data availability -- References.Ye
A unified dataset of colocated sewage pollution, periphyton, and benthic macroinvertebrate community and food web structure from Lake Baikal (Siberia)
Sewage released from lakeside development can introduce nutrients and micropollutants that can restructure aquatic ecosystems. Lake Baikal, the world’s most ancient, biodiverse, and voluminous freshwater lake, has been experiencing localized sewage pollution from lakeside settlements. Nearby increasing filamentous algal abundance suggests benthic communities are responding to localized pollution. We surveyed 40-km of Lake Baikal’s southwestern shoreline from 19 to 23 August 2015 for sewage indicators, including pharmaceuticals, personal care products, and microplastics, with colocated periphyton, macroinvertebrate, stable isotope, and fatty acid samplings. The data are structured in a tidy format (a tabular arrangement familiar to limnologists) to encourage reuse. Unique identifiers corresponding to sampling locations are retained throughout all data files to facilitate interoperability among the dataset’s 150+ variables. For Lake Baikal studies, these data can support continued monitoring and research efforts. For global studies of lakes, these data can help characterize sewage prevalence and ecological consequences of anthropogenic disturbance across spatial scales
Effects of spatially heterogeneous lakeside development on nearshore biotic communities in a large, deep, oligotrophic lake
Sewage released from lakeside development can reshape ecological communities. Nearshore periphyton can rapidly assimilate sewage-associated nutrients, leading to increases of filamentous algal abundance, thus altering both food abundance and quality for grazers. In Lake Baikal, a large, ultra-oligotrophic, remote lake in Siberia, filamentous algal abundance has increased near lakeside developments, and localized sewage input is the suspected cause. These shifts are of particular interest in Lake Baikal, where endemic littoral biodiversity is high, lakeside settlements are mostly small, tourism is relatively high (~1.2 million visitors annually), and settlements are separated by large tracts of undisturbed shoreline, enabling investigation of heterogeneity and gradients of disturbance. We surveyed sites along 40 km of Baikal’s southwestern shore for sewage indicators—pharmaceuticals and personal care products (PPCPs) and microplastics—as well as periphyton and macroinvertebrate abundance and indicators of food web structure (stable isotopes and fatty acids). Summed PPCP concentrations were spatially related to lakeside development. As predicted, lakeside development was associated with more filamentous algae and lower abundance of sewagesensitive mollusks. Periphyton and macroinvertebrate stable isotopes and essential fatty acids suggested that food web structure otherwise remained similar across sites; yet, the invariance of amphipod fatty acid composition, relative to periphyton, suggested that grazers adjust behavior or metabolism to compensate for different periphyton assemblages. Our results demonstrate that even low levels of human disturbance can result in spatial heterogeneity of nearshore ecological responses, with potential for changing trophic interactions that propagate through the food web
Data harmonization and federated learning for multi-cohort dementia research using the OMOP common data model:A Netherlands consortium of dementia cohorts case study
Background: Establishing collaborations between cohort studies has been fundamental for progress in health research. However, such collaborations are hampered by heterogeneous data representations across cohorts and legal constraints to data sharing. The first arises from a lack of consensus in standards of data collection and representation across cohort studies and is usually tackled by applying data harmonization processes. The second is increasingly important due to raised awareness for privacy protection and stricter regulations, such as the GDPR. Federated learning has emerged as a privacy-preserving alternative to transferring data between institutions through analyzing data in a decentralized manner. Methods: In this study, we set up a federated learning infrastructure for a consortium of nine Dutch cohorts with appropriate data available to the etiology of dementia, including an extract, transform, and load (ETL) pipeline for data harmonization. Additionally, we assessed the challenges of transforming and standardizing cohort data using the Observational Medical Outcomes Partnership (OMOP) common data model (CDM) and evaluated our tool in one of the cohorts employing federated algorithms. Results: We successfully applied our ETL tool and observed a complete coverage of the cohorts’ data by the OMOP CDM. The OMOP CDM facilitated the data representation and standardization, but we identified limitations for cohort-specific data fields and in the scope of the vocabularies available. Specific challenges arise in a multi-cohort federated collaboration due to technical constraints in local environments, data heterogeneity, and lack of direct access to the data. Conclusion: In this article, we describe the solutions to these challenges and limitations encountered in our study. Our study shows the potential of federated learning as a privacy-preserving solution for multi-cohort studies that enhance reproducibility and reuse of both data and analyses.</p
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