Abundance of Zoobenthos on the Nearshore Slope Near the Rocky Coast of the Island of Valaam (Lake Ladoga)

Abstract

The bottom communities of a nearshore zone of Valaam archipelago (Ladoga Lake) have been investigated. The stations were located in the littoral, sublittoral and profundal on the depth 1–25 m. The three regions with different characteristics of the coast shore and relief were researched. The sampler-syringe was used to collect benthos because it works the whole of grounds variety in the nearshore. The quantative characteristics of the bottom communities had been optimally described with the depth ranges. The wave activity has significantly affected only on the numbers of zoobenthos in the upper 10 m. The changes of numbers and biomass have been described more preciously by the openness of the bays in depth from 1 to 10 m. There were the biggest numbers and biomass of zoobenthos in littoral of the close bay. In the semi-close bay and on the open coast the maximum abundance of benthic invertebrates shifted in sublittoral (depth 8 m), where waves less affected on the benthic communities. The types of ground had affected significantly only on taxonomical composition. In general, preferential effect on the quantity characteristics of benthos on the rocky slope zone have features of shore (openness and depth patterns). These data can be used for the analyses of next influences on the nearshore benthic community and for the analyses and modelling the commercial resources and their forage base.