Ecopath modelling approach for the impact assessment of a small-scale coastal aquaculture system in Goa, India

Abstract

In this study, the ecological impacts of introduction of cage aquaculture employing small cages integrating shellfish and finfish in coastal water bodies of Goa, situated in the west coast of India were analysed using Ecopath with Ecosim model. A multispecies cage aquaculture system incorporating Lutjanus argentimaculatus, Etroplus suratensis and Perna viridis was established in an estuarine ecosystem. The Ecopath model identified 12 functional groups starting from detritus (trophic level=1) to large benthic carnivores (trophic level=3.72). The ecosystem statistics such as total system throughput (8672 g m-2 year-1), gross efficiency (0.001), primary production/respiration (1.4), net system production (1028.2 g m-2 year-1) and system omnivory index (0.26) indicated that the ecosystem was highly productive and in a developing stage. With a medium rate of recycling (Finn’s Cycling Index=11.7%), high system throughput, high system overhead (79%) and moderate omnivory index (0.26), the food web was found to be immature having an organized trophic network with high production. Simulations of the various expanding scenarios for the cage culture within the ecosystem were explored using Ecosim. A scenario in which two cages each for pearlspot and red snapper and 20 mussel ropes was identified as a sustainable solution without sacrificing the threshold biomass for the functional groups of fish species [WU1] . The study provided useful insights and methodology towards assessing aquaculture in coastal ecosystems in terms of ecosystem structure and function.

Exploring multiple stressor effects with Ecopath, Ecosim, and Ecospace: Research designs, modeling techniques, and future directions

“…Collection of wild-caught juveniles to raise in fish farms from the surrounding ecosystem has been simulated by adding respective fisheries (Forrestal et al, 2012;Manju Lekshmi et al, 2020). The escape of transgenic salmon from fish farms has been modeled by adding an escapee compartment to an existing model and forcing its biomass to simulate gradual or catastrophic escapes (Li et al, 2014;Izquierdo-Gomez et al, 2016).…”

“…• Oxygen concentration as habitat capacity layer in Ecospace • Habitat changes (e.g. loss of seagrass meadows): See section "Habitat loss and restoration" AquacultureFerriss et al, 2016;Forrestal et al, 2012;Han et al, 2018Han et al, , 2017Izquierdo-Gomez et al, 2016;Li et al, 2014;Lin et al, 2009;Livne et al, 2020;Manju Lekshmi et al, 2020;Serpetti et al, 2021;Wu et al, 2016 • Inclusion of farmed groups and of feed (as detritus) in food web model• Provision of habitat by mediation functions • Predator attraction in Ecospace via habitat suitability • Environmental response functions or mediation functions for modeling predator deterrent measures Offshore energy Alexander et al, 2016; Halouani et al, 2020; Raoux et al, 2019, 2017; Serpetti et al, 2021 • Hard substrate as Ecospace habitat or forcing biomass increase of species expected to benefit • Exclusion of fisheries by reducing fishing in Ecosim or by MPAs in Ecospace • Bird mortality from collisions as fishery…”

Exploring multiple stressor effects with Ecopath, Ecosim, and Ecospace: Research designs, modeling techniques, and future directions

“…Han et al (2017a) explored the trophic effects of shellfish aquaculture by including compartments for farmed shellfish, then forcing their biomass step-by-step to zero (simulating the ecosystem after a hypothetical removal of all shellfish farms); a follow-up study explored interactions of shellfish aquaculture with fishing (Han et al, 2018). Collection of wild-caught juveniles to raise in fish farms from the surrounding ecosystem has been simulated by adding respective fisheries (Forrestal et al, 2012;Manju Lekshmi et al, 2020). Provision of hard substrate has been modeled as mediation functions in Ecosim or as a designated habitat in Ecospace (see also Section 6.3.3).…”

“…AquacultureFerriss et al, 2016;Forrestal et al, 2012;Han et al, 2018Han et al, , 2017Izquierdo-Gomez et al, 2016;Li et al, 2014;Lin et al, 2009;Livne et al, 2020;Manju Lekshmi et al, 2020;Serpetti et al, 2021;Wu et al, 2016 • andYou, 2021;McGill et al, 2017;Niiranen et al, 2008;Rohal et al, 2020;Sandberg et al, 2007;Suprenand et al, 2019;Tierney et …”

The combined effects of predation, fishing, and ocean productivity on salmon species targeted by marine mammals in the northeast Pacific

“…The ecosystem modelling platform Ecopath with Ecosim (EwE) was ranked the most applied tool for modelling marine and aquatic ecosystems worldwide [46,47]. The software has been used to address a variety of questions, including fisheries impacts [44,48,49], efficiency of marine protected areas [46,50,51], habitat loss [52,53], interactions between marine species [54][55][56][57][58], environmental impact assessments [59][60][61][62], pollution [63] as well as climate change and associated environmental variations [64][65][66]. This modelling approach has been widely applied in the northeast Pacific, with about 37 EwE models created to date for different areas extending from the Aleutian Islands to Mexico [67].…”