Marine Biogeochemistry Under The Influence of (Mesopelagic) Fish and Fisheries: An Ecosystem Modeling Study

The ocean and the marine ecosystems are important controllers of the global carbon cycle. They play a pivotal role in capturing atmospheric carbon into the ocean body, transforming it into organic carbon through photosynthesis and transporting it to the depths of the ocean. Fish, which has a significant role in the marine food webs, is thought to have a considerable impact on carbon export. More specifically, fish has a control on plankton dynamics as a predator, it provides nutrient to the ecosystem by its metabolic activities and it has the ability of moving actively and transporting materials. Fishing is also expected to impact carbon cycle because it directly changes the fish biomasses. However, how fish impacts the biogeochemistry of marine ecosystems is not studied extensively. The aim of this study is to analyze the impact of fish and fisheries on marine biogeochemical processes by setting up an end-to-end model, which simulates lower and higher tropic levels of marine ecosystems simultaneously. For this purpose, a one dimensional biogeochemical model simulating lower tropic level dynamics (e.g. carbon export, nutrient cycles) and an food web model simulating fisheries exploitation and higher tropic level dynamics were online and two-way coupled. Representing the marine ecosystem from one end to the other, the coupled model served as a tool for the analysis of fishing impacts on marine biogeochemical dynamics. Results obtained after incorporation of higher trophic level model changed the plankton compositions and enhanced detritus pools and increased carbon export. Additionally, our model showed that active movement of fish contributed to transport of carbon from surface to the deeper parts of the ocean. Moreover, results after applying different fishing intensities indicated that changes in fisheries exploitation levels directly influence the marine nutrient cycles and hence, the carbon export. Depending on the target and the intensity of fisheries, considerable changes in the biogeochemical responses observed. In conclusion, unlike the models that do not represent the fish explicitly, we demonstrate how marine biogeochemical processes are impacted by the activity of fish assemblages and fisheries exploitation.
Ocean Sciences Meeting 2018, 11 - 16 February 2018


Dişa, Deniz; Salihoğlu, Barış; Akoğlu, Ekin; Department of Oceanography (2016-9-23)
The ocean has a crucial role in global carbon cycle. Marine ecosystems are responsible for storing the carbon within the ocean body by means of uptaking atmospheric carbon into the ocean, transforming it into organic carbon through photosynthesis and transporting to the profound depths of the ocean. Playing a significant role in the marine food webs, grazing on plankton and providing nutrient to ecosystem by its metabolic activities, fish is thought to have a considerable impact on carbon export. For this r...
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Salihoğlu, Barış (2016-02-15)
Improved structure and mechanisms of carbon export and sequestration within marine ecosystem models is vital to better understand and predict changes in the global carbon cycle. We have implemented a 1D lower trophic ecosystem model at long-term time-series stations (BATS and ESTOC) in the North Atlantic for the years 1996-2000. We have investigated the dynamics of the productivity and carbon export, and mechanisms regulating them. Our simulations agree with the previous observations that show similar produ...
European Union Basin-scale Analysis, Synthesis and Integration (EURO-BASIN)
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Lau, Kimberly V.; Maher, Kate; Altıner, Demir; Kelley, Brian M.; Kump, Lee R.; Lehrmann, Daniel J.; Silva-Tamayo, Juan Carlos; Weaver, Karrie L.; Yu, Meiyi; Payne, Jonathan L. (2016-03-01)
Delayed Earth system recovery following the end-Permian mass extinction is often attributed to severe ocean anoxia. However, the extent and duration of Early Triassic anoxia remains poorly constrained. Here we use paired records of uranium concentrations ([U]) and U-238/U-235 isotopic compositions (delta U-238) of Upper Permian- Upper Triassic marine limestones from China and Turkey to quantify variations in global seafloor redox conditions. We observe abrupt decreases in [U] and delta U-238 across the end-...
Citation Formats
D. Dişa, E. Akoğlu, and B. Salihoğlu, “Marine Biogeochemistry Under The Influence of (Mesopelagic) Fish and Fisheries: An Ecosystem Modeling Study,” presented at the Ocean Sciences Meeting 2018, 11 - 16 February 2018, 2018, Accessed: 00, 2021. [Online]. Available: