Characterizing the habitat function of bivalve aquaculture using underwater video

B Ferriss,K Litle,L Conway-Cranos,P Kiffney,L Hoberecht,K Veggerby,M Bogeberg,B Sanderson,J Toft

doi:10.3354/aei00418

Abstract

Bivalve aquaculture is an expanding coastal industry with the potential to modify the habitat of fish and crab species, affecting their refuge, movement, and feeding. The habitat function of shellfish aquaculture is not yet well understood, in part due to difficulties in data collection using traditional methods. Underwater video was used to observe fish and crab species’ affiliations with cultured Pacific oyster Crassostrea gigas and Manila clam Venerupis philippinarum aquaculture sites in comparison to uncultured reference sediment and eelgrass habitats. Sites were monitored in 9 locations across 3 regions of Puget Sound, Washington, USA, in the summers of 2017 and 2018. Of the 3038 fish and crabs observed, 98% were represented by Embiotocidae (surfperch), crabs, three-spined stickleback Gasterosteus aculeatus, Cottidae (sculpins), and Pleuronectiformes (flatfish). Overall, the affiliations of fish and crabs with bivalve aquaculture varied by species groups, culture type, and regional environmental and habitat conditions. These interactions varied on a scale of approximately 150 km, highlighting variation of aquaculture-ecological interactions at a scale not previously recorded in Puget Sound. Species composition varied between aquaculture and non-aquaculture habitats in 2 of the 3 regions studied. Species diversity and richness in aquaculture habitats varied regionally, relative to reference habitats. Pelagic species were more abundant in aquaculture and reference sites that had vertical structure, but abundances of demersal and benthic species on aquaculture habitat relative to reference sites varied regionally. The availability of habitats within intertidal regions, including varying types of aquaculture, could determine community structure for marine organisms such as fish and crab.

Highlights

Bivalve aquaculture has the potential to provide social-economic benefits to coastal communities while providing habitat function for nearshore ecosystems (Alleway et al 2019, Gentry et al 2020)
Bivalve aquaculture has been considered in the restoration context via artificial reef production (MayerPinto et al 2017, Alleway et al 2019); the habitat function of aquaculture is not as well understood when the purpose is primarily economic, and potentially includes gear associated with the shellfish grow-out phase
While species composition varied between combined aquaculture and non-aquaculture habitats in 2 of 3 regions, we found regionally distinct associations between the fish and crab species and the habitats associated with shellfish aquaculture

Summary

Introduction

Bivalve aquaculture has the potential to provide social-economic benefits to coastal communities while providing habitat function for nearshore ecosystems (Alleway et al 2019, Gentry et al 2020). Aquacult Environ Interact 13: 439–454, 2021 structure may vary by type of structure (Loke & Todd 2016), latitude (Bracewell et al 2018), surrounding habitat (Grabowski et al 2005), scale of habitat relevant to the focal species (Loke et al 2015), species group (Tews et al 2004), and types of complexity (Tews et al 2004), adding to the ongoing discussion of whether artificial habitat has higher abundance of fish due to aggregation or enhanced production (Bohnsack 1989) Because of these uncertainties, questions remain as to whether this habitat complexity paradigm applies to bivalve aquaculture, and if aquaculture provides habitat functions unique or similar to co-occurring, natural habitat structure (e.g. seagrasses) (Dumbauld et al 2011). Do shellfish cultivation sites provide similar habitat functions across scales of 100s of km? Understanding the function of bivalve aquaculture as subtidal habitat in these regional contexts can facilitate the consideration of potential habitat-related changes in the marine community in the sustainable development of aquaculture

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