Marine molluscs in nearshore habitats of the United Arab Emirates : decadal changes and species of public health significance

Abstract

This paper describes the results of three qualitative surveys of marine molluscs conducted in December 2010 and May 2011 and 2012 in nearshore benthic habitats along the Arabian Gulf and Gulf of Oman coasts of the United Arab Emirates. Findings are compared to historical studies, focusing on extensive surveys from the 1960s and 1970s. Molluscan species of public health significance are identified based on their potential as vectors of algal toxins in light of the recent occurrence of harmful algal blooms (HABs) in the region. Habitats sampled included intertidal sand or gravel beaches, rocks and jetties, sheltered soft-sediment flats and mangroves, and shallow subtidal coral reefs. The present study showed differences in taxonomic composition and decreased species richness of gastropods compared to a previous mollusc survey conducted in the early 1970s, reflecting the probable impacts of extensive, ongoing coastal development activities, although other environmental stressors may play a contributing role. The major habitat change found in the current survey was replacement of natural “rocky” substrates with manmade jetties and breakwaters. Of the 27 live gastropod species collected, 7 predatory or scavenging species were identified as potential biotoxin vectors: Thais savignyi, T. tissoti, T. lacera, Murex scolopax, Nassarius persicus, Hexaplex kuesterianus and Rapana sp. Of the 22 live bivalve species collected, the following 11 suspension-feeders were deemed to be potential vectors of HAB toxins based on their body size and feeding mode: three venerid clams (Circenita callipyga, and Tivela ponderosa that are consumed locally, and Amiantis umbonella), the widespread encrusting rock oyster, Saccostrea cuccullata, also consumed locally, two pearl oyster species, Pinctada spp., the prickly pen shell Pinna muricata, the scallop Chlamys livida, the cockle Acrosterigma lacunosa, and the facultative suspension-feeding tellinids Asaphis violascens and Hiatula rosea.