Structure of settlements of Macoma balthica in the southern knee of the Kola Bay

Abstract

The study of seasonal dynamics of size-mass structure of Macoma balthica settlements has been investigated on the littoral zone of the southern part of the Kola Bay. Age structure has been calculated; data on the density and biomass of settlements have been obtained; the distribution of the mollusk on the littoral has been shown. On the littoral zone of the Kola Bay makoms are found everywhere, mostly inhabiting the lower and middle horizons of the littoral; this distribution depends on the content of food particles, which is an indirect indicator of the granulometric composition of soil and total organic content. The highest indicators of biomass and the number of settlements have been marked in the intertidal zone near the village of Abram-mys. This is due to the presence of silty-sandy soil – the most suitable habitat for shellfish, as the abundance of settlement figures increases as the silting of sand. The increase in the density of makom settlements in autumn occurs due to the active settling of juveniles. Shellfish from the right bank settlements surpass others on the morphometric parameters. Large shell sizes are explained by the presence of streams ensuring the inflow of food particles. Researches of the size-distribution of Macoma balthica mass parameters have shown that their values are increased from the upper to the lower horizon littoral as in the lower horizon the enhanced water exchange contributes to the self-cleaning processes and provides shellfish by food. The dominance of mollusks of younger age groups (0–3 years) is characteristic for all settlements. Clams with the maximum age of 8 years have been found in the New Bridge area. The presence in the samples of large number of mollusks of younger age groups indicates the normal development of Macoma balthica settlements.

Keywords

• Macoma balthica
• Kola Bay
• biomass
• population density