The production ecology of the subtidal benthos of the Forth Estuary, Scotland
M. Elliott, C.J.L. Taylor

The high productivity of estuarine intertidal macrobenthos has been well documented but less is known of the productivity of subtidal areas adjacent to those intertidal areas and of the relationship between the two areas. This study assessed the subtidal macrobenthic biomass and production of the Forth, an industrialised Scottish estuary bordering the North Sea. The findings are based on a synoptic study of 80 stations and an intensive study over a 15 month period at 2 stations typical of certain benthic associations. In general, the subtldal populations were relatively unproductive. The assessment of the production of 6 polychaete species resulted in P/B values lower than those in the literature for polychaetes in general. However, the specific comparison of Nephtys spp. shows the Forth populations to be smaller but with P/B similar to those found elsewhere. In contrast, the echiurid Echiurus echiurus (Pallas) had a short life span and higher productivity (PIB: 4.73) and a correspondingly large impact on the community. By incorporating data for the intertidal areas, the study shows that with a progression down the estuary and for a given area, the subtidal production increases while that for the intertidal decreases. The biomass and production of the poorest subtidal areas were lower than those for the intertidal by up to two orders of magnitude. It is of significance to the predator populations that although the subtidal area was almost 70% of the total, its biomass and production were 38% and 47% respectively. These findings have implications when considering the functioning of an estuary in relation to anthropogenic changes. The loss of intertidal area through reclamation or pollution effects will have a disproportionate effect on the system because of the depressed subtidal productivity.

Keywords: secondary production, soft-bottom benthos, subtidal, estuaries.
Contents of this volume Sci. Mar. 53(2-3) : 531-541 Back PDF
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