Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, United States of America.
Graduate School of Environmental Science, Hokkaido University, Akkeshi, Hokkaido, Japan.
PLoS One. 2018 May 24;13(5):e0197753. doi: 10.1371/journal.pone.0197753. eCollection 2018.
Coastal fisheries are in decline worldwide, and aquaculture has become an increasingly popular way to meet seafood demand. While finfish aquaculture can have substantial adverse effects on coastal ecosystems due mostly to necessary feed inputs, bivalves graze on natural phytoplankton and are often considered for their positive ecosystem services. We conducted two independent studies to investigate the effects of long-line Crassostrea gigas oyster aquaculture on Zostera marina seagrass beds and associated epibiont communities in Akkeshi-ko estuary, Japan. Results from both studies yielded no evidence of an effect of oyster aquaculture on the morphology, density, or biomass of Z. marina, but significant differences were apparent in the epibiont community. Reference seagrass beds located away from aquaculture had higher seagrass epiphyte loads and higher abundances of amphipods. Conversely, seagrass beds below aquaculture lines had higher sessile polychaete biomass and higher isopod abundances. Our results suggest that the presence of oyster aquaculture may have indirect effects on seagrass by changing epibiont community composition and relative abundances of species. One proposed mechanism is that cultured oysters feed on epiphytic diatoms and epiphyte propagules before they can settle on the seagrass, which reduces epiphyte loads and influences subsequent faunal settlement. If carefully implemented and monitored, long-line oyster aquaculture may be a sustainable option to consider as bivalve aquaculture expands to meet global seafood demand, but further work is needed to fully assess and generalize the community-level effects on seagrass epibionts.
沿海渔业在全球范围内不断衰退，水产养殖已成为满足海鲜需求的一种越来越受欢迎的方式。虽然贝类养殖由于需要饲料投入，可能对沿海生态系统产生重大的不利影响，但双壳贝类以天然浮游植物为食，通常因其积极的生态系统服务而受到重视。我们进行了两项独立的研究，以调查日本别海河口长桩牡蛎养殖对海草床和相关附生生物群落的影响。这两项研究的结果都没有表明牡蛎养殖对 Zostera marina 海草的形态、密度或生物量有影响，但附生生物群落存在明显的差异。远离养殖区的参考海草床具有更高的海草附生物负载和更高丰度的蔓足类动物。相反，养殖线以下的海草床具有更高的固着多毛类生物量和更高的等足类动物丰度。我们的研究结果表明，牡蛎养殖的存在可能通过改变附生物群落组成和物种的相对丰度，对海草产生间接影响。一种提出的机制是，养殖牡蛎会在附生硅藻和附生物繁殖体附着在海草上之前吃掉它们，从而降低附生物负载并影响随后的动物定殖。如果经过精心实施和监测，长桩牡蛎养殖可能是一种可持续的选择，可以考虑扩大贝类养殖以满足全球海鲜需求，但需要进一步的工作来充分评估和推广对海草附生物的群落水平影响。
