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On the structuring role of Saduria entomon (L.) on shallow water zoobenthos
Eva Sandberg and Erik Bonsdorff
Annales Zoologici Fennici
Vol. 27, No. 3, Biology and ecology of glacial relict Crustacea: Nordic research conference 20—23 April 1988, Tvärminne Zoological Station, University of Helsinki, Finland (1990), pp. 279-284
Published by: Finnish Zoological and Botanical Publishing Board
Stable URL: http://www.jstor.org/stable/23736049
Page Count: 6
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In shallow, northern Baltic archipelago waters, predatory epibenthic invertebrates are rare in relation to fully marine environments. One such predator is the relict isopod Saduria entomon L., which is faced with a choice of prey organisms of varying ecological origin, including marine or estuarine species on the one hand, and "limnic" species on the other. In clearly sublittoral areas S. entomon has no principal invertebrate competitors for food, but in shallow water regions odonata larvae may play a similar regulatory role on the benthic community. Against this background, the structuring role of S. entomon for the benthic infauna in shallow brackish waters was tested in relation to (a) one major invertebrate food competitor (Libellula quadrimaculata; Odonata), and (b) prey species of varying ecological origin (marine or estuarine, exemplified by Macoma balthica and Corophium volutator, and "limnic", e.g. Asellus aquaticus and larval chironomids). Field and aquarium experiments illustrated that S. entomon is technically capable by predation to exhibit a regulatory pressure on all prey items offered, but that the effects at community level are difficult to distinguish from the natural variation within the ecosystem. On shallow bottoms S. entomon exhibits similar predatory effects to the larvae of the dragonfly L. quadrimaculata. It is concluded that S. entomon in shallow Baltic archipelagoes is something of a "universal competitor", capable of affecting populations regardless of their functional origin.
Annales Zoologici Fennici © 1990 Finnish Zoological and Botanical Publishing Board