Meeting Abstract
P2.4 Friday, Jan. 4 Population Snapshots: Laternulid Bivalves of Kungkrabaen Bay, Thailand PREZANT, R.S.*; SUTCHARIT, C.; CHALERMWAT, K.; Montclair State Univ.; Chulalongkorn Univ., Bangkok; Burapha Univ., Chonburi prezantr@mail.montclair.edu
Bivalves of the family Laternulidae (Anomalodesmata) are distributed from polar to tropical waters but, although often found in large numbers, remain poorly known. We examined two species of laternulids residing in close but non-overlapping populations in Kungkrabaen Bay, Thailand. Laternula truncata was commonly found deeply burrowed in open mud/sand flat regions with higher densities closer to hummocks of the mangrove trees Avicennia alba and A. marina. Densest populations were found in quadrats with lowest levels of sediment organics. Intertidal macroinvertebrate biodiversity was weakly correlated with laternulid density while evenness declined with increased L. truncata population size. There was a correlation between population density and bivalve size. Population cohort distribution for L. truncata indicated continuous recruitment although at the time of sampling the smallest cohorts were absent. The latter suggests a recruitment failure or stochastic cohort displacement. L. cf. corrugata, smaller and less common than L. truncata, was found deeper in the mangrove forest and closer to the sediment surface. The latter sediments had a higher sand concentration compared to the more open flat. L. cf. corrugata had heavily eroded shells and were often associated with the rootlets of the mangrove tree Sonneratia alba. Of the two laternulid species, only L. cf. corrugata showed evidence of predation by the drilling gastropod Chicoreus capucinus. Contrary to most literature, both bivalves, especially among smaller specimens, were capable of readily reburrowing. There are substantive behavioral, ecological and morphological differences between these two taxa reflecting a need for systematic revision of the family.