This work was carried out in the context of an integrated project planned to quantify the dynamics of biophilic elements (C, N, P and Si) in a tidal estuary in the Seto Inland Sea, Japan, and to assess the roles played by the macrobenthos on the processes. In the present study, we set a transect line of five stations on an intertidal flat near the low tide shore line and an adjacent subtidal station ca. 200 metres distant from the intertidal zone. The macrobenthic communities were investigated quantitatively. Major parameters of surface sediments (Chl a, pheo-pigments, total organic carbon and acid-volatile sulfide) were simultaneously determined at each station in attempt to correlate the seasonal changes of the macrobenthic communities with the chemical characteristics of the sediments. During the spring-summer 1994, the development of a high biomass of the macroalgae Ulva sp., which covered large areas of the tidal flat, did not significantly affect the growth of two dominant bivalve species, Ruditapes philippinarum and Musculista senhousia. However, between September and October 1994, the rapid decomposition of the macroalgae led to a distrophic crisis. A sharp increase of pheo-pigment, total organic carbon and acid-volatile sulfide contents at the surface sediments coincided with the catastrophic mortality of R. philippinarum on the intertidal flat, whose biomass crashed from 563 ± 163 gWW m-2 (September 1994) to 77.0 ± 61.2 gWW m-2 (October 1994), and a drastic reduction of the macrobenthos on the subtidal station, where the total biomass decreased from 179 gWW m-2 (July 1994) to 11.3 gWW m-2 (October 1994). This work represents a clear example of the increasing threat to benthic life due to eutrophication and an alert for indispensable countermeasures for a sustainable use of tidal estuaries, such as reduction of nutrient import from land.
Macrobenthic mass mortality in a tidal estuary in the Seto Inland Sea
Magni P;
1998-01-01
Abstract
This work was carried out in the context of an integrated project planned to quantify the dynamics of biophilic elements (C, N, P and Si) in a tidal estuary in the Seto Inland Sea, Japan, and to assess the roles played by the macrobenthos on the processes. In the present study, we set a transect line of five stations on an intertidal flat near the low tide shore line and an adjacent subtidal station ca. 200 metres distant from the intertidal zone. The macrobenthic communities were investigated quantitatively. Major parameters of surface sediments (Chl a, pheo-pigments, total organic carbon and acid-volatile sulfide) were simultaneously determined at each station in attempt to correlate the seasonal changes of the macrobenthic communities with the chemical characteristics of the sediments. During the spring-summer 1994, the development of a high biomass of the macroalgae Ulva sp., which covered large areas of the tidal flat, did not significantly affect the growth of two dominant bivalve species, Ruditapes philippinarum and Musculista senhousia. However, between September and October 1994, the rapid decomposition of the macroalgae led to a distrophic crisis. A sharp increase of pheo-pigment, total organic carbon and acid-volatile sulfide contents at the surface sediments coincided with the catastrophic mortality of R. philippinarum on the intertidal flat, whose biomass crashed from 563 ± 163 gWW m-2 (September 1994) to 77.0 ± 61.2 gWW m-2 (October 1994), and a drastic reduction of the macrobenthos on the subtidal station, where the total biomass decreased from 179 gWW m-2 (July 1994) to 11.3 gWW m-2 (October 1994). This work represents a clear example of the increasing threat to benthic life due to eutrophication and an alert for indispensable countermeasures for a sustainable use of tidal estuaries, such as reduction of nutrient import from land.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
