Predicting Impacts of Offshore Monoculture Farm Expansion in Ultra-Oligotrophic Waters of the Levantine Basin

Abstract

The aim of this brief research report was to define the consequential shifts in biomass and trophic structure of an ecosystem surrounding an offshore monoculture fish farm in Israel. It attempts to clarify the impact of the industry expansion and input of artificial fish pellets on functional group biomasses. We account for the direct addition of artificial food pellets, the metabolic wastes from the caged fish in a mass-balance food web model (Ecopath), as well as the temporal expansion of the farm's production capacity to 21,000 t over a 30-year period (Ecosim). In the static mass-balance model of the food web, the addition of the fish cages at its current production size of 1000 t does not adversely affect the system, and trophic energy transfer is still dependent on primary production versus the detrital pathway. The model suggests a semi-stable ecosystem with low trophic interactions. With time, the increase in fish farming at the site is characterized by an increase of all functional group biomasses at the site over the 30year period. The accumulation in detritus most notably correlates to greater biomass for all benthic functional niches and their secondary consumers. It is, therefore, apt to develop an indicator species list to indicate negative site disturbance. In summary, the sediment column condition will be the main indicator for ecosystem stability, as well as the increase in apex predators that are attracted to the site from the accumulation of discards at the cage bottom.

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

“…Eleven studies explored ecosystem changes driven by aquaculture. The common foundation of modeling stressors related to aquaculture in EwE is to include farmed organisms as functional groups and feed as a detritus compartment (Lin et al, 2009;Livne et al, 2020;Han et al, 2017Han et al, , 2018. Changes in aquaculture activities can be modeled by forcing the biomasses of these compartments (Wu 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…”

Ecotrophic perspective in fisheries management: a review of Ecopath with Ecosim models in European marine ecosystems

“…The consequences of alien species and fisheries have also been studied in other parts of the Levantine basin such as the insular shelf ecosystem of Cyprus (Michailidis et al, 2019;Michailidis et al, 2023) and the Gulf of Mersin in Turkey (Saygu et al, 2020). Moreover, EwE was applied to model the effects of aquaculture (Livne et al, 2020), to inform marine spatial planning (Shabtay et al, 2018), and to assess energy- (Grossowicz et al, 2020) and economy-related (Peled et al, 2020;Michael-Bitton et al, 2022) questions.…”

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

“…The common foundation of modeling stressors related to aquaculture in the EwE framework is to include farmed organisms as functional groups and feed as a detritus compartment. For example, Livne et al (2020) simulated the expansion of a fish farm and associated increases in pellet inputs. 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).…”

“…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 …”