The influence of tidal dynamics on exchange of meroplankton (Bivalvia, Gastropoda) between the Busse Lagoon and adjacent marine area of the Aniva Bay

Exchange of Bivalvia and Gastropoda larvae between the Aniva Bay and Busse Lagoon is described on results of the plankton survey conducted in the connecting Suslov Channel in 2014. Taxonomic composition of meroplankton is described. Tide-induced water exchange through the channel is estimated, as well. The total water ux is evaluated for each tidal cycle using the data on the water level in the lagoon and on the area of its water mirror. The main factor of the larvae exchange is the tidal water ow that reaches the rate of 4 knots both for ebb and tide currents. The meroplankton from the lagoon is transported by the ebb current rather far to the sea, and its reverse drift with the tide current back to the lagoon looks doubtful, so export of the meroplankton from the lagoon is detected, with certain seasonal dynamics. The export is the most intensive in early summer (July) because of earlier spawning in the lagoon, which water is warmed quicker on shallows. The exchange decreases in August, when the water temperature is the highest both in the lagoon and in the Aniva Bay and many species spawn actively in both areas. Both reverse transport and export of the larvae are low in September because of the water cooling and cessation of the spawning.