Occurrence of the large mangrove mud creeper Terebralia palustris (Linnaeus, 1767) (Gastropoda; Potamididae) within the Arabian Gulf, at and near Qeshm Island, Iran, in the Strait of Hormuz

Naturalists and archaeologists familiar with the UAE know very well that, despite the frequent presence of shells of the Potamidid gastropod Terebralia palustris in coastal deposits and archaeological contexts along the Arabian Gulf coast of the UAE, at various sites of various ages (Feulner, 2000; Gruber et al., 2005; Hellyer & Aspinall, 2006), this large and distinctive edible gastropod is not found alive in that area today. It is likewise absent in Qatar and Bahrain to the north, although it thrives at Khor Kalba on the Gulf of Oman coast of the UAE. The reasons for the contemporary absence of T. palustris within the Arabian Gulf remain speculative. Elsewhere in the Indo-Pacific it is typically (Houbrick, 1991; Fratini et al., 2004), although not always (Feulner, 2000; Fratini, pers. comm.), closely associated with mangrove forests, so the reduced presence of mangroves in Qatar and Bahrain, where they are near the margin of their winter frost tolerance, has been tentatively invoked to explain the absence of T. palustris there. However, alternative explanations cannot be ruled out, including, inter alia: (1) extreme water temperature and/or salinity (both significantly elevated in the Arabian Gulf summertime); (2) the role of ocean currents on the dispersal and recruitment of pelagic larvae; (3) the over-exploitation of T. palustris (and perhaps associated mangrove forests as well) by earlier human populations; and (4) reduced freshwater input to the Arabian Gulf in general and the UAE's coastal lagoons in particular, due to increasing regional aridity. In order to attempt to test these alternative hypotheses, I have previously suggested the possibility of identifying a natural laboratory, specifically, by "confirm[ing] (or deny[ing]) the presence of T. palustris in the extensive mangroves inshore of Qeshm Island, Iran, in the Strait of Hormuz. This site is more northerly than Bahrain but it is situated between the delta of the seasonal Mehran River and the mouth of the Kol River, where freshwater influx may remain relatively high in comparison to other southern Gulf locations" (Feulner, 2000). In fact, I thereafter attempted to join in a proposed visit to Qeshm Island in company with a group of other amateur naturalists, but satisfactory arrangements proved elusive.