Seasonal changes in infaunal community structure in a hypertrophic brackish canal: Effects of hypoxia, sulfide, and predator-prey interaction.
We conducted a one-year survey of macrozoobenthic community structure at 5 stations in a eutrophic canal in inner Tokyo Bay, focusing on the impacts of hypoxia, sediment H2S, and species interaction in the littoral soft-bottom habitats. Complete defaunation or decreasing density of less-tolerant taxa occurred under hypoxia during warmer months, especially at subtidal or sulfidic stations; this was followed by rapid recolonization by opportunistic polychaetes in fall-winter. Sedimentary H2S increased the mortality of macroinvertebrates under hypoxia or delayed population recovery during recolonization. The density of several polychaetes (e.g., Pseudopolydora reticulata) declined in winter, coincident with immigration of the predator Armandia lanceolata. This suggests that absence of A. lanceolata under moderate hypoxia enabled the proliferation of prey taxa. We conclude that oxygen concentration, sediment H2S, and hypoxia-induced changes in species interactions are potential drivers for spatiotemporal changes in macrozoobenthic assemblage structure in hypoxia-prone soft-bottom communities.
National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. Electronic address: gen@nies.go.jp.
Gen
G
Kanaya
National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
Yasuo
Y
Nakamura
Nihon Mikuniya Corporation, 3-25-10 Mizonokuchi, Takatsu, Kawasaki, Kanagawa 213-0001, Japan.
Tomoyoshi
T
Koizumi
National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan; Seikai National Fisheries Research Institute, FRA, Nagasaki 851-2213, Japan.
Katsumasa
K
Yamada
D000693:Anaerobiosis / Q000502:physiology*; D000818:Animals; D061006:Bays; D044822:Biodiversity; D020387:Food Chain; D019015:Geologic Sediments / Q000737:chemistry; D006862:Hydrogen Sulfide / Q000032:analysis / Q000494:pharmacology*; D007448:Invertebrates / Q000187:drug effects* / Q000502:physiology*; D007564:Japan; D011156:Population Density; D054712:Salinity; D012621:Seasons
D006862:Hydrogen Sulfide
Eutrophication; Macrozoobenthos; Oxygen depletion; Stable isotopes; Succession; Sulphide; Trophic interaction