scholarly journals A fully coupled ecosystem model to predict the foraging ecology of apex predators in the California Current

2016 ◽  
Vol 556 ◽  
pp. 273-285 ◽  
Author(s):  
J Fiechter ◽  
LA Huckstadt ◽  
KA Rose ◽  
DP Costa
Keyword(s):  
Foraging Ecology ◽  
California Current ◽  
Ecosystem Model ◽  
Apex Predators ◽  
Fully Coupled

scholarly journals Integrating multiple chemical tracers to elucidate the diet and habitat of Cookiecutter Sharks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aaron B. Carlisle ◽  
Elizabeth Andruszkiewicz Allan ◽  
Sora L. Kim ◽  
Lauren Meyer ◽  
Jesse Port ◽  
...  
Keyword(s):  
Trophic Ecology ◽  
Foraging Ecology ◽  
Isotope Analysis ◽  
Environmental Dna ◽  
Small Sample ◽  
Apex Predators ◽  
Central Pacific ◽  
Chemical Tracers ◽  
Important Prey ◽  
Tracer Techniques

AbstractThe Cookiecutter shark (Isistius brasiliensis) is an ectoparasitic, mesopelagic shark that is known for removing plugs of tissue from larger prey, including teleosts, chondrichthyans, cephalopods, and marine mammals. Although this species is widely distributed throughout the world’s tropical and subtropical oceanic waters, like many deep-water species, it remains very poorly understood due to its mesopelagic distribution. We used a suite of biochemical tracers, including stable isotope analysis (SIA), fatty acid analysis (FAA), and environmental DNA (eDNA), to investigate the trophic ecology of this species in the Central Pacific around Hawaii. We found that large epipelagic prey constituted a relatively minor part of the overall diet. Surprisingly, small micronektonic and forage species (meso- and epipelagic) are the most important prey group for Cookiecutter sharks across the studied size range (17–43 cm total length), with larger mesopelagic species or species that exhibit diel vertical migration also being important prey. These results were consistent across all the tracer techniques employed. Our results indicate that Cookiecutter sharks play a unique role in pelagic food webs, feeding on prey ranging from the largest apex predators to small, low trophic level species, in particular those that overlap with the depth distribution of the sharks throughout the diel cycle. We also found evidence of a potential shift in diet and/or habitat with size and season. Environmental DNA metabarcoding revealed new prey items for Cookiecutter sharks while also demonstrating that eDNA can be used to identify recent prey in stomachs frozen for extended periods. Integrating across chemical tracers is a powerful tool for investigating the ecology of elusive and difficult to study species, such as meso- and bathypelagic chondrichthyans, and can increase the amount of information gained from small sample sizes. Better resolving the foraging ecology of these mesopelagic predators is critical for effective conservation and management of these taxa and ecosystems, which are intrinsically vulnerable to overfishing and exploitation.

Modeling mercury cycling in the marine environment

2020 ◽  
Author(s):  
Johannes Bieser ◽  
Ute Daewel ◽  
Corinna Schrum
Keyword(s):  
Numerical Models ◽  
Marine Ecosystem ◽  
Ecosystem Model ◽  
Trophic Levels ◽  
Modeling Framework ◽  
Modeling Tools ◽  
Large Variability ◽  
Marine Ecosystem Model ◽  
Set Up ◽  
Fully Coupled

<p>Five decades of Hg science have shown the <strong>tremendous complexity of the global Hg cycle</strong>. Yet, the pathways that lead from anthropogenic Hg emissions to MeHg exposure through sea food are not fully comprehended. Moreover, the observed amount of MeHg in fish exhibits a large temporal and spatial variability that we cannot predict yet. A key issue is that fully speciated Hg measurements in the ocean are difficult to perform and thus we will never be able to achieve a comprehensive spatial and temporal coverage.</p><p>Therefore, we need complex modeling tools that allow us to fill the gaps in the observations and to predict future changes in the system under changing external drivers (emissions, climate change, ecosystem changes). Numerical models have a long history in Hg research, but so far have virtually only addressed inorganic Hg cycling in atmosphere and oceans.</p><p>Here we present a novel 3d-hydrodynamic mercury modeling framework based on fully coupled compartmental models including atmosphere, ocean, and ecosystem. The generalized high resolution model has been set up for European shelf seas and was used to model the transition zone from estuaries to the open ocean. Based on this model we present our findings on intra- and inter-annual dynamics and variability of mercury speciation and distribution in a coastal ocean. Moreover, we present the first results on the dynamics of mercury bio-accumulation from a fully coupled marine ecosystem model. Most importantly, the model is able to reproduce the large variability in methylmercury accumulation in higher trophic levels.</p>

scholarly journals Ocean fronts drive marine fishery production and biogeochemical cycling

2015 ◽  
Vol 112 (6) ◽  
pp. 1710-1715 ◽  
Author(s):  
C. Brock Woodson ◽  
Steven Y. Litvin
Keyword(s):  
Habitat Degradation ◽  
California Current ◽  
Ecosystem Model ◽  
Nutrient Supply ◽  
Ocean Fronts ◽  
High Productivity ◽  
Marine Fishery ◽  
Trophic Pathways ◽  
Biogeochemical Hotspots

Long-term changes in nutrient supply and primary production reportedly foreshadow substantial declines in global marine fishery production. These declines combined with current overfishing, habitat degradation, and pollution paint a grim picture for the future of marine fisheries and ecosystems. However, current models forecasting such declines do not account for the effects of ocean fronts as biogeochemical hotspots. Here we apply a fundamental technique from fluid dynamics to an ecosystem model to show how fronts increase total ecosystem biomass, explain fishery production, cause regime shifts, and contribute significantly to global biogeochemical budgets by channeling nutrients through alternate trophic pathways. We then illustrate how ocean fronts affect fishery abundance and yield, using long-term records of anchovy–sardine regimes and salmon abundances in the California Current. These results elucidate the fundamental importance of biophysical coupling as a driver of bottom–up vs. top–down regulation and high productivity in marine ecosystems.

scholarly journals Explicit silicate cycling in the Kiel Marine Biogeochemistry Model, version 3 (KMBM3) embedded in the UVic ESCM version 2.9

2020 ◽  
Author(s):  
Karin Kvale ◽  
David P. Keller ◽  
Wolfgang Koeve ◽  
Katrin J. Meissner ◽  
Chris Somes ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Primary Production ◽  
Large Scale ◽  
Climate Model ◽  
Net Primary Production ◽  
Coupled Model ◽  
Co2 Concentration ◽  
Ecosystem Model ◽  
New Model ◽  
Fully Coupled

Abstract. We describe and test a new model of biological marine silicate cycling, implemented in the University of Victoria Earth System Climate Model (UVic ESCM) version 2.9. This new model adds diatoms, which are a key aspect of the biological carbon pump, to an existing ecosystem model. The new model performs well against important ocean biogeochemical indicators and captures the large-scale features of the marine silica cycle. Furthermore it is computationally efficient, allowing both fully-coupled, long-timescale transient simulations, as well as "offline" transport matrix spinups. We assess the fully-coupled model against modern ocean observations, the historical record since 1960, and a business-as-usual atmospheric CO2 forcing to the year 2300. The model simulates a global decline in net primary production (NPP) of 1.3 % having occurred since the 1960s, with the strongest declines in the tropics, northern mid-latitudes, and Southern Ocean. The simulated global decline in NPP reverses after the year 2100 (forced by the extended RCP CO2 concentration scenario), and NPP returns to pre-industrial rates by 2300. This recovery is dominated by increasing primary production in the Southern Ocean, mostly by calcifying phytoplankton. Large increases in calcifying phytoplankton in the Southern Ocean offset a decline in the low latitudes, producing a global net calcite export in 2300 that varies only slightly from pre-industrial rates. Diatoms migrate southward in our simulations, following the receding Antarctic ice front, but are out-competed by calcifiers across most of their pre-industrial Southern Ocean habitat. Global opal export production thus drops to 50 % of its pre-industrial value by 2300. Model nutrients phosphate, silicate, and nitrate build up along the Southern Ocean particle export pathway, but dissolved iron (for which ocean sources are held constant) increases in the upper ocean. This different behaviour of iron is attributed to a reduction of low-latitude NPP (and consequently, a reduction in both uptake and export and particle, including calcite, scavenging), an increase in seawater temperatures (raising the solubility of particle forms), and stratification that "traps" the iron near the surface. These results are meant to serve as a baseline for sensitivity assessments to be undertaken with this model in the future.

Spatial and temporal variability in the diet of Pacific marten (Martes caurina) on Haida Gwaii: an apex predator in a highly modified ecosystem

2021 ◽  
Author(s):  
David N Breault ◽  
Chris J. Johnson ◽  
Melissa Todd ◽  
Sergei S Verenitch ◽  
Michael P Gillingham
Keyword(s):  
Marine Invertebrates ◽  
Foraging Ecology ◽  
Diet Analysis ◽  
Bone Collagen ◽  
Food Sources ◽  
Marine Resources ◽  
Spatial And Temporal Variability ◽  
Apex Predators ◽  
Haida Gwaii ◽  
Carbon And Nitrogen

Knowledge of the diet ecology of apex predators in insular island ecosystems has direct applications to the conservation of endemic species at risk of extinction. We used stable isotopes of carbon and nitrogen to infer resource-use strategies of a native predator, the Pacific marten (Martes caurina Merriam, 1890), in a highly modified ecosystem on Haida Gwaii, British Columbia, Canada. We used Bayesian isotopic mixing models to estimate the relative contributions of different food sources to marten diet across seasons and during overall lifetime, and to determine how diet varied with different levels of access to marine resources. Isotopes of carbon and nitrogen measured in hair and muscle tissue suggested that marten consumed salmon (3–17%) and berries (25–37%) seasonally; these diet groups were relatively minor components of the lifetime diet. Analysis of bone collagen suggested that terrestrial fauna – including birds, deer, small mammals, and invertebrates – contributed the most to diet (41–55%), and marine invertebrates (38–48%), not salmon (0–3%), were the main allochthonous marine nutrient subsidy to lifetime diet. Plasticity in foraging ecology, combined with a broad dietary niche, introduced prey, notably the invasive Sitka black-tailed deer (Odocoileus hemionus sitkensis Merriam, 1898), as well as abundant marine resources, may allow marten to outcompete other native and endemic carnivores on Haida Gwaii.

Risks of ocean acidification in the California Current food web and fisheries: ecosystem model projections

2017 ◽  
Vol 23 (4) ◽  
pp. 1525-1539 ◽  
Author(s):  
Kristin N. Marshall ◽  
Isaac C. Kaplan ◽  
Emma E. Hodgson ◽  
Albert Hermann ◽  
D. Shallin Busch ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Food Web ◽  
California Current ◽  
Ecosystem Model

Climate variability and sardine recruitment in the California Current: A mechanistic analysis of an ecosystem model

2018 ◽  
Vol 27 (6) ◽  
pp. 602-622 ◽  
Author(s):  
Dimitrios V. Politikos ◽  
Enrique N. Curchitser ◽  
Kenneth A. Rose ◽  
David M. Checkley ◽  
Jerome Fiechter
Keyword(s):  
Climate Variability ◽  
California Current ◽  
Ecosystem Model ◽  
Mechanistic Analysis
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