Peculiarities of population structure and biocenotic relationships of Rapana venosa (Valenciennes, 1846) (Gastropoda, Muricidae) in the Donuzlav Bay (the Black Sea)

Abstract

The Western Pacific gastropod Rapana venosa (Valenciennes, 1846) is classified among the hundred most dangerous invasive species of the Black and Mediterranean seas. Moreover, it is recognized as a dangerous invader in a number of coastal water areas on both sides of the Atlantic Ocean that determines the relevance of the study of population characteristics and biocenotic relationships of the rapa whelk in the areas of its invasion. The analysis of a previously unexplored R. venosa population in the Donuzlav Bay (the Northwestern Crimea) of the Black Sea in 2020 showed as follows: in the occurrence of an abundant and diverse food base, the rapa whelk does not form mass aggregations and, consequently, does not significantly affect benthic biocenoses. This fact is also confirmed by the ratio of biomass of the predatory mollusc and its prey. R. venosa mean biomass in the study area was 3.8 g·m−2, and the mean biomass of its food objects (Bivalvia) was 162.8 g·m−2. The features of the population structure and biocenotic relationships of the rapa whelk in the Donuzlav Bay are considered and discussed for the first time. Direct underwater observations and indirect evidence indicate that the distribution of this invader is controlled by aboriginal predators, crabs. The main species limiting R. venosa abundance in the study area is the crab Carcinus aestuarii Nardo, 1847.

Keywords

• biocenoses
• algae
• invasive species
• crabs
• molluscs
• predator–prey