Differences in effects of grazing by deposit-feeders Hydrobia ulvae (Pennant) (Gastropoda : Prosobranchia) and Corophium arenarium Crawford (Amphipoda) on sediment microalgal populations. II. Quantitative effects
Morrisey, D.J. (1988). Differences in effects of grazing by deposit-feeders Hydrobia ulvae (Pennant) (Gastropoda : Prosobranchia) and Corophium arenarium Crawford (Amphipoda) on sediment microalgal populations. II. Quantitative effects. J. Exp. Mar. Biol. Ecol. 118(1): 43-53. https://dx.doi.org/10.1016/0022-0981(88)90121-9
In: Journal of Experimental Marine Biology and Ecology. Elsevier: New York. ISSN 0022-0981; e-ISSN 1879-1697, more
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| Keywords |
Corophium arenarium Crawford, 1937 [WoRMS]; Hydrobia ulvae (Pennant, 1777) [WoRMS]
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| Author keywords |
Deposit-feeder; Grazer; Microalga; Microcosm |
| Abstract |
An earlier study showed that the growth rate of the prosobranch Hydrobia ulvae (Pennant) in microcosms is reduced at high population densities, but that the presence of the amphipod Corophium arenarium Crawford does not affect snail growth rate. In the present study, the effect of these two grazing species on sediment microalgal numbers was measured in the same microcosms. Increase in grazer density caused a decrease or a reduced rate of increase in algal standing stock, compared with ungrazed controls. The maximum reduction in algal numbers achieved by either species on its own was to a level equivalent to 30% of the control values. In microcosms with both Hydrobia and Corophium present, the negative effect on algal populations was greater than in those with the same or greater density of Hydrobia alone. This may indicate that Corophium is more efficient at digesting sediment microalgae or that there are qualitative differences in the diets of the two species. Such differences may explain the absence of an interspecific competitive effect on snail growth rate. Contrary to the findings of many previous studies, low levels of grazing did not lead to an increase in microalgal standing stock. |
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