Chamelea gallina in the coastal waters of the Anapa bay bar (the Black Sea) as a carbonate sediment producer

Abstract

Summary The paper presents preliminary results of monitoring the population of the bivalve Chamelea gallina, which is the main source of biogenic carbonates for the Anapa bay bar beaches (the Black Sea). It is shown that by 2017, the biomass of the clams decreased more than twice compared to 2010, but began to increase in 2018. The average sizes of C. gallina are clearly divided in terms “year” – “section” – “age”. At the same time, interannual variations of the average size are very strong in all age groups. The average shell length of C. gallina significantly increased in 2018 compared to 2016, and especially – to 2017. This may be caused by the population decline of the predator Rapana venosa feeding on clams. Geographic differences in the shell length between sections are not directly related to the distribution of biogenic elements (nitrogen and phosphorus). The differences in longevity and shell size between C. gallina from the Anapa region and distant populations from the other parts of the distribution area are likely related to its significant negative correlation with the growth rate, which in turn negatively correlates with latitude.