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Positive Community Interactions of Artificial Eastern Oyster Reefs (Crassostrea virginica) on Cotransplanted Eelgrass (Zostera marina) Growth and Survival
2023 -
DeLany, Flynn
Seagrass and oyster habitats are two key habitat-forming species that contribute significantly to coastal system function and resilience. However, seagrass populations have been disappearing at accelerating rates over recent decades, and global restoration efforts have had low rates of transplant establishment in target areas. Implementation of known facilitations between eelgrasses, oysters, and their communities may result in increased yields for traditional restoration methodologies. We focused on the co-planting of eelgrass with artificial eastern oyster reefs to explore the impact of documented facilitations on eelgrass transplants from oyster communities and their associated community assemblages.
Seagrass and oyster habitats are two key habitat-forming species that contribute significantly to coastal system function and resilience. However, seagrass populations have been disappearing at accelerating rates over recent decades, and global restoration efforts have had low rates of transplant establishment in target areas. Implementation of known facilitations between eelgrasses, oysters, and their communities may result in increased yields for traditional restoration methodologies. We focused on the co-planting of eelgrass with artificial eastern oyster reefs to explore the impact of documented facilitations on eelgrass transplants from oyster communities and their associated community assemblages.
Prevalence of Autotrophy in Non-humic African Lakes
2022 - Cédric Morana, Alberto V. Borges, Loris Deirmendjian, William Okello, Hugo Sarmento, Jean-Pierre Descy, Ismael A. Kimirei & Steven Bouillon
Heterotrophic respiration of organic matter (OM) is thought to dominate over aquatic primary production (PP) in most freshwater lake ecosystems. This paradigm implies that lateral transport of OM from the terrestrial biosphere subsidize the major fraction of aquatic respiration and that many lakes are a net source of carbon dioxide (CO2) to atmosphere. Nevertheless, African lakes were absent of the datasets upon which this paradigm was built. Here, we report a comprehensive and methodologically consistent data set of pelagic PP and community respiration (CR) obtained over the last decade in contrasting non-humic African lakes including 5 of the East African Great lakes (Tanganyika, Kivu, Edward, Albert, Victoria) and smaller shallow lakes located in Eastern Africa.
Heterotrophic respiration of organic matter (OM) is thought to dominate over aquatic primary production (PP) in most freshwater lake ecosystems. This paradigm implies that lateral transport of OM from the terrestrial biosphere subsidize the major fraction of aquatic respiration and that many lakes are a net source of carbon dioxide (CO2) to atmosphere. Nevertheless, African lakes were absent of the datasets upon which this paradigm was built. Here, we report a comprehensive and methodologically consistent data set of pelagic PP and community respiration (CR) obtained over the last decade in contrasting non-humic African lakes including 5 of the East African Great lakes (Tanganyika, Kivu, Edward, Albert, Victoria) and smaller shallow lakes located in Eastern Africa.
Morphological and genetic mechanisms underlying the plasticity of the coral Porites astreoides across depths in Bermuda
2022 - Federica Scucchia, Kevin Wong, Paul Zaslansky, Hollie M. Putnam, Gretchen Goodbody-Gringley, Tali Mass
The widespread decline of shallow-water coral reefs has fueled interest in assessing whether mesophotic reefs can act as refugia replenishing deteriorated shallower reefs through larval exchange. Here we explore the morphological and molecular basis facilitating survival of planulae and adults of the coral Porites astreoides (Lamarck, 1816; Hexacorallia: Poritidae) along the vertical depth gradient in Bermuda. We found differences in micro-skeletal features such as bigger calyxes and coarser surface of the skeletal spines in shallow corals. Yet, tomographic reconstructions reveal an analogous mineral distribution between shallow and mesophotic adults, pointing to similar skeleton growth dynamics.
The widespread decline of shallow-water coral reefs has fueled interest in assessing whether mesophotic reefs can act as refugia replenishing deteriorated shallower reefs through larval exchange. Here we explore the morphological and molecular basis facilitating survival of planulae and adults of the coral Porites astreoides (Lamarck, 1816; Hexacorallia: Poritidae) along the vertical depth gradient in Bermuda. We found differences in micro-skeletal features such as bigger calyxes and coarser surface of the skeletal spines in shallow corals. Yet, tomographic reconstructions reveal an analogous mineral distribution between shallow and mesophotic adults, pointing to similar skeleton growth dynamics.
The Role of Abiotic and Biotic Processes in Regulating Benthic Ecosystem Function Along a Productivity Gradient
2022 - Framsted, Nicholas
"The benthic zone of lakes can be a hotspot for lake energy flows and nutrient cycling. Indeed, the notion of benthic “ooze” and its role in the recycling of nutrients forms a conceptual cornerstone of ecology (Lindeman 1942). Benthic habitats can vary from soft, muddy sediments rich in organic matter and nutrients to bare rock covered by thin biofilms. These habitats form the linkage between lake and watershed, and support a range of ecosystem processes—from exchange of groundwater nutrients, internal nutrient cycling, mineralization of organic matter, heterotrophic respiration, and benthic algal production—that each vary in importance between different waterbodies. Clear Lake, CA, and Lake Tahoe represent two systems that span a gradient in trophic level, depth, and underlying geology. "
"The benthic zone of lakes can be a hotspot for lake energy flows and nutrient cycling. Indeed, the notion of benthic “ooze” and its role in the recycling of nutrients forms a conceptual cornerstone of ecology (Lindeman 1942). Benthic habitats can vary from soft, muddy sediments rich in organic matter and nutrients to bare rock covered by thin biofilms. These habitats form the linkage between lake and watershed, and support a range of ecosystem processes—from exchange of groundwater nutrients, internal nutrient cycling, mineralization of organic matter, heterotrophic respiration, and benthic algal production—that each vary in importance between different waterbodies. Clear Lake, CA, and Lake Tahoe represent two systems that span a gradient in trophic level, depth, and underlying geology. "
Plasticity of Porites astreoides Early Life History Stages Suggests Mesophotic Coral Ecosystems Act as Refugia in Bermuda
2021 - Gretchen Goodbody-Gringley, Federica Scucchia, Rebecca Ju, Alex Chequer, Shai Einbinder, Stephane Martinez, Hagai Nativ, Tali Mass
As the devastating impacts of global climate change and local anthropogenic stressors on shallow-water coral reefs are expected to rise, mesophotic coral ecosystems have increasingly been regarded as potential lifeboats for coral survival, providing a source of propagules to replenish shallower reefs. Yet, there is still limited knowledge of the capacity for coral larvae to adjust to light intensities that change with depth. This study elucidates the mechanisms underlying plasticity during early life stages of the coral Porites astreoides that enable survival across broad depth gradients.
As the devastating impacts of global climate change and local anthropogenic stressors on shallow-water coral reefs are expected to rise, mesophotic coral ecosystems have increasingly been regarded as potential lifeboats for coral survival, providing a source of propagules to replenish shallower reefs. Yet, there is still limited knowledge of the capacity for coral larvae to adjust to light intensities that change with depth. This study elucidates the mechanisms underlying plasticity during early life stages of the coral Porites astreoides that enable survival across broad depth gradients.
Always ready? Primary production of Arctic phytoplankton at the end of the polar night
2021 - Clara J. M. Hoppe
The end of the polar night with the concurrent onset of photosynthetic biomass production ultimately leads to the spring bloom, which represents the most important event of primary production for the Arctic marine ecosystem. This dataset shows, for the first time, significant in situ biomass accumulation during the dark–light transition in the high Arctic, as well as the earliest recorded positive net primary production rates together with constant chlorophyll a-normalized potential for primary production through winter and spring. The results indicate a high physiological capacity to perform photosynthesis upon re-illumination, which is in the same range as that observed during the spring bloom.
The end of the polar night with the concurrent onset of photosynthetic biomass production ultimately leads to the spring bloom, which represents the most important event of primary production for the Arctic marine ecosystem. This dataset shows, for the first time, significant in situ biomass accumulation during the dark–light transition in the high Arctic, as well as the earliest recorded positive net primary production rates together with constant chlorophyll a-normalized potential for primary production through winter and spring. The results indicate a high physiological capacity to perform photosynthesis upon re-illumination, which is in the same range as that observed during the spring bloom.
Vertical Habitat Gradients: Comparing Phytoplankton Dynamics in Lakes with Low to Moderate Dissolved Organic Carbon Concentration
2021 - Matthew J. Farragher
Concentrations of dissolved organic carbon (DOC) increased across lakes of Maine for several decades before stabilizing or decreasing in recent years. To investigate the seasonal effects of DOC on phytoplankton habitat structure, I assessed vertical gradients of temperature, oxygen, light, and chlorophyll in four lakes in Acadia National Park from under ice through fall turnover in 2020. Lake DOC concentrations ranged from low (~2 mg L-1) to moderate (~4 mg L-1). Low-DOC lakes were clearer, with greater mean Secchi depths (9-15 m) than moderateDOC lakes (5-6 m). Moderate-DOC lakes experienced hypolimnetic anoxia in the summer and had more variable concentrations and vertical gradients of chlorophyll a.
Concentrations of dissolved organic carbon (DOC) increased across lakes of Maine for several decades before stabilizing or decreasing in recent years. To investigate the seasonal effects of DOC on phytoplankton habitat structure, I assessed vertical gradients of temperature, oxygen, light, and chlorophyll in four lakes in Acadia National Park from under ice through fall turnover in 2020. Lake DOC concentrations ranged from low (~2 mg L-1) to moderate (~4 mg L-1). Low-DOC lakes were clearer, with greater mean Secchi depths (9-15 m) than moderateDOC lakes (5-6 m). Moderate-DOC lakes experienced hypolimnetic anoxia in the summer and had more variable concentrations and vertical gradients of chlorophyll a.
Under Ice and Early Summer Phytoplankton Dynamics in Two Arctic Lakes with Differing DOC
2021 - V. Hazuková, B. T. Burpee, I. McFarlane-Wilson, J. E. Saros
We investigated Arctic lake phytoplankton response along vertical gradients in the water column during seasonal succession from ice-covered to open-water conditions. Two oligotrophic lakes in West Greenland with different dissolved organic carbon (DOC) concentrations were selected. We assessed which factors: (1) promote under-ice growth of phytoplankton, and (2) trigger shifts in the community structure. Our results suggest that DOC is an important driver of the seasonal distribution of phytoplankton biomass—high DOC exacerbates light limitation under ice resulting in low phytoplankton biomass, but supports phytoplankton growth during the open-water period when photolytic and biological degradation of organic matter contributes to the pool of available nutrients.
We investigated Arctic lake phytoplankton response along vertical gradients in the water column during seasonal succession from ice-covered to open-water conditions. Two oligotrophic lakes in West Greenland with different dissolved organic carbon (DOC) concentrations were selected. We assessed which factors: (1) promote under-ice growth of phytoplankton, and (2) trigger shifts in the community structure. Our results suggest that DOC is an important driver of the seasonal distribution of phytoplankton biomass—high DOC exacerbates light limitation under ice resulting in low phytoplankton biomass, but supports phytoplankton growth during the open-water period when photolytic and biological degradation of organic matter contributes to the pool of available nutrients.
Drivers of Biogeochemical Variability in a Central California Kelp Forest: Implications for Local Amelioration of Ocean Acidification
2020 - Heidi K. Hirsh, Kerry J. Nickols, Yuichiro Takeshita, Sarah B. Traiger, David A. Mucciarone, Stephen Monismith, Robert B. Dunbar
Kelp forests are among the world's most productive marine ecosystems, and they have the potential to locally ameliorate ocean acidification (OA). In order to understand the contribution of kelp metabolism to local biogeochemistry, we must first quantify the natural variability and the relative contributions of physical and biological drivers to biogeochemical changes in space and time. We deployed an extensive instrument array in Monterey Bay, CA, inside and outside of a kelp forest to assess the degree to which giant kelp (Macrocystis pyrifera) locally ameliorates present-day acidic conditions which we expect to be exacerbated by OA.
Kelp forests are among the world's most productive marine ecosystems, and they have the potential to locally ameliorate ocean acidification (OA). In order to understand the contribution of kelp metabolism to local biogeochemistry, we must first quantify the natural variability and the relative contributions of physical and biological drivers to biogeochemical changes in space and time. We deployed an extensive instrument array in Monterey Bay, CA, inside and outside of a kelp forest to assess the degree to which giant kelp (Macrocystis pyrifera) locally ameliorates present-day acidic conditions which we expect to be exacerbated by OA.
Calcification and organic productivity at the world's southernmost coral reef
2020 - Kay L. Davis, Ashly McMahon, Rogger E. Correa, Isaac R. Santos
Estimates of coral reef calcification and organic productivity provide valuable insight to community functionality and the response of an ecosystem to stress events. High-latitude coral reefs are expected to experience rapid changes in calcification rates and become refugia for tropical species following climate change and increasing bleaching events. Here, we estimate ecosystem-scale calcification and organic productivity at the world's southernmost coral reef using seawater carbon chemistry observations (Lord Howe Island, Australia). We reduce uncertainties in metabolic calculations by producing a detailed bathymetric model and deploying two current meters to refine residence time and volume estimates.
Estimates of coral reef calcification and organic productivity provide valuable insight to community functionality and the response of an ecosystem to stress events. High-latitude coral reefs are expected to experience rapid changes in calcification rates and become refugia for tropical species following climate change and increasing bleaching events. Here, we estimate ecosystem-scale calcification and organic productivity at the world's southernmost coral reef using seawater carbon chemistry observations (Lord Howe Island, Australia). We reduce uncertainties in metabolic calculations by producing a detailed bathymetric model and deploying two current meters to refine residence time and volume estimates.
