Successions of benthic/planktonic community structure and environmental factors in estuaries and tidal-flats

Representative Organization: Tohoku University

2014/04/01 - 2015/03/31
monthly

Estuaries and tidal flats in the Sendai Bay

Field survey

Estuaries and tidal flats are one of the most important environments in marine ecosystem. Monitoring environmental factors of water and sediment qualities, and investigating species composition and biomass in macrobenthos and plankton in these waters are necessary to understand their successions after the great earthquake and tsunami in tidal flats not only from the point of ecology but also from the fishery science.

Topology of Gamo Lagoon has changed drastically after the earthquake and tsunami and is still continuing to change. Water temperature and dissolved oxygen did not change largely but salinity showed unstable. There was almost no benthic animals just after the tsunami. The opportunistic polychaetes firstly appeared, which occupied approximately 90 % of the total benthic community. Although the number of benthic animals was observed to increase as the time succeeded, the density of them again decreased after the influence of the typhoon-derived freshwater observed in August. The polychaete families Nereididae and Spionidae appeared in the initial stage, and they both had planktonic and direct development larvae, respectively. The dominant polychaete species changed from H. diadroma which shows direct development to H. atoka which possesses planktonic larvae. Pseudopolydora reticulata was newly recorded from Japan. Polychaetes and amphipods dominated stage sifted to the next stage with abundant of bivalve species Nuttalia japonica and Arthritica reikoae after September 2012. At present, Hediste and Capitella species dominated and the amphipods decreased. The macrobenthic animals are thought to be still under unstable condition.

FY2014 Successions of benthic/planktonic community structure and environmental factors in estuaries and tidal-flats