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Bivalve aquaculture has rapidly expanded in shallow coastal habitats, leading to substantial changes in the natural environment. While the grazing pressure of mussels (Mytilus edulis) on phytoplankton and zooplankton has been well documented, cascading effects of plankton depletion on the development and survival of resident fish and invertebrate larvae remains largely unexplored. This study experimentally assessed the impact of control (no mussel grazing), low (20 mussels·m−3) and high (80 mussels·m−3) mussel densities on a model community composed of various phytoplankton and zooplankton and how changes in plankton characteristics influence the development and survival of lobster (Homarus americanus) larvae.

Plankton depletion by mussel grazing negatively impacts the fitness of lobster larvae

Bivalves act as ecosystem engineers, strongly influencing pelagic and benthic environments through filtration, nutrient cycling, and biodeposition. In the water column, dense bivalve populations can exert strong top-down control on phytoplankton, reducing seston concentrations (“depletion”), altering plankton community structure, and redirecting energy away from zooplankton and higher trophic levels. On the seafloor, biodeposits increase organic loading beneath farms, potentially altering sediment chemistry, oxygen dynamics, and benthic community composition along a gradient from minimal change to hypoxia and dominance by opportunistic species. Aquaculture infrastructure can also modify habitats by increasing water clarity and seagrass growth in some contexts, while creating physical structures that alter hydrodynamics, provide new habitat, and facilitate the spread of nonindigenous species and disease.

Modelling Carrying Capacity of Bivalve Aquaculture: A Review of Definitions and Methods

The growth of animal aquaculture requires ever more feed. Yet, fish and crustacean farming is argued to be sustainable because wild fish use is low and has improved over time. Here, accounting for trimmings and by-products from wild fish in aquaculture feed, and using four different sources of industry-reported feed composition data, we find ratios of fish inputs to farmed outputs of 0.36 to 1.15—27 to 307% higher than a previous estimate of 0.28. Furthermore, a metric that incorporates wild fish mortality during capture and excludes unfed systems raises the wild fish mortality–to–farmed fish output ratio to 0.57 to 1.78. We also evaluate terrestrial ingredients in aquaculture feeds. Widely cited estimates of declines in wild fish use from 1997 to 2017 entailed a trade-off of more than fivefold increase in feed crops over the same period. Our assessment challenges the sustainability of fed aquaculture and its role in food security

Feeding Global Aquaculture