[A-CG42] 沿岸海洋⽣態系─１．⽔循環と陸海相互作⽤

[ACG42-09] 開放性海浜沖合の海底に高密度で発達する底生生物の巣穴：ベントスのろ過食が海底生態系に及ぼす影響

*清家 弘治^1,2、小森 康太郎^1,2、田村 亨^1,2 (1.産業技術総合研究所・地質調査総合センター、2.東京大学大学院新領域創成科学研究科自然環境学専攻)

キーワード：底生生物、ろ過食、砂浜

Sandy beach is the commonest environment type in coastal settings facing the open ocean and comprises ~30% of the ice free coastlines worldwide. However, interactions between benthic organisms and the seafloor environment are less well understood for sandy beach ecosystems. In particular, organism-environment interactions in the nearshore zone (water depths of <30 m and 2-3 km offshore from the coastline, sensu Short, 1999) remain poorly understood. Recently, Seike et al. (2020) revealed that the effect of benthic filtering by the suspension feeding shrimp Austinogebia narutensis (Decapoda: Upogebiidae) on the abundance of primary producers (chlorophyll a concentration) in the water column along the Kashimanada coast, central Japan, facing the northwestern Pacific Ocean. Suspension feeding of the shrimp reduces the abundance of primary producers in the bottom water. Here, we report a similar phenomenon from the nearshore zone of the Kujukuri coast, central Japan. Burrows of a filter feeding upogebiid shrimp occurred densely in the sea bottom where chlorophyll a concentration was remarkably low. We concluded that the filtering effect of the shrimp has a profound impact on coastal marine ecosystems, and may have occurred in nearshore settings since the Mesozoic.


References

Seike, K., Banno, M., Watanabe, K., Kuwae, T., Arai, M., & Sato, H. (2020). Benthic filtering reduces the abundance of primary producers in the bottom water of an open sandy beach system (Kashimanada coast, Japan). Geophysical Research Letters, 47(1), e2019GL085338.
Short, A. D. (1999). Handbook of beach and shoreface morphodynamics. Chichester, UK: Wiley.