Spatiotemporal variations of zooplankton community structure in the oyster (Crassostrea gigas)-macroalgae reef dual ecosystems adjacent to Luanhe River Estuary.

Majority of macrozooplankton have a wider dietary niche breadth and utilize small invertebrates, microzooplankton and mesozooplankton, so effect on primary production might be through trophic cascading effect. To better understand the ecosystem structure of benthic oyster-macroalgae reefs, we analyzed zooplankton community structure before (July 2016) and after (from September 2016 to October 2017) the construction of benthic reefs in the 2 km2 sea ranch area in Xiangyun Cove, Tangshan, China. We identified 57 zooplankton species, including the 12 cnidarian (e.g., Clytia hemisphaerica Linnaeus and Eirene ceylonensis Browne), 1 ctenopharyngodon (Pleurobrachia globosa Moser), 24 crustacean (e.g., Calanus sinicus Brodsky, Paracalanus parvus Claus, Labibocera euchaeta Glesbrecht, Labibocera bipinnata Tanaka, Calanopia thompsoni Scott, and Centropages dorsispinatus Thompson), 1 chaetognath (Sagitta crassa Tokioka), 1 urochordate species (Oikopleura dioica Fol), and 18 species of planktonic polychaete and gastropod larvae. The zooplankton density and biomass values before reef construction were 266.14 ind/m3 and 2.72 mg/m3, respectively, and those after reef construction were 138.06 ind/m3 and 32.91 mg/m3, respectively. The biomass trend was as follow: October 2017 (89.08 mg/m3) > August 2017 (70.97) > September 2016 (3.17) > July 2016 (2.72) > June 2017 (0.86) > May 2017 (0.44). The common dominant organisms were crustaceans and chaetognaths. According to the RDA ranking results, water temperature was positively correlated with the Shannon-Wiener diversity index and Margalef's richness indexes. With the increasement of Margalef's richness index, the value of dissolved oxygen content showed a significant negative correlation with zooplankton abundance. The results of this study are applicable to sustainable development and management strategies of coastal reef ecosystems and provide a basis for further surveys of secondary productivity in the sea ranch area.