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

Abstract

The bottom communities of the nearshore zone of the Valaam archipelago (Lake Ladoga) have been investigated. The stations were located in the littoral, sublittoral, and profundal at depths of 1–25 m. Three regions with different characteristics of the coast shore and relief were researched. A 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 significantly affected only the numbers of zoobenthos in the upper 10 m. The openness of the bay had a greater influence on the abundance and biomass of benthos in the range of 1–10 m, presumably taking into account the influence of reflected waves. The biggest numbers and biomass of zoobenthos were in the littoral of the close bay. In the semiclose bay and on the open coast, the maximum abundance of benthic invertebrates shifted in the sublittoral (depth >8 m), where waves affected the benthic communities less. The types of ground significantly affected only the taxonomical composition. In general, the preferential effect on the quantity characteristics of benthos on the rocky slope zone had the features of a shore (openness and depth patterns). These data can be used for inspections of the next influences on the nearshore benthic community and for analyzing and modeling the commercial resources and their forage base.