The population dynamics of Nassarius festivus (Gastropoda: Nassariidae) on three environmentally different beaches in Hong Kong

Abstract

The population dynamics of Nassarius festivus were studied over a period of 21 months on three Hong Kong beaches experiencing different degrees of anthropogenic organic input. Among the three, Starfish Bay showed the highest level of food availability in the form of carrion comprising fishing bycatch and fauna damaged as a result of clam-digging by villagers. Consequently, catchability of N. festivus was highest here, individuals attained the largest shell height and had the shortest life span, ranging from 22 to 24 months. Conversely, Tai Mong Tsai wasjudged to have the lowest level of anthropogenic organic input and food availability. As a result, catchability of N. festivus was lowest, individuals were smallest and had a longer life span, ranging from 23 to 28 months. Tai Tam Bay lay between the extremes of Starfish Bay and Tai Mong Tsai, such that organic pollution was considered intermediate and food availability low. Catchability and maximum size attained by N. festivus-were also intermediate and life span ranged from 23 to 29 months. The life-history traits exhibited by N. festivus in these different areas thus reflect environmental parameters, in particular food availability.