Niche adaptation in two marine gastropods,Monodonta turbiformisandM. turbinata

Abstract

Several behavioural, physiological and morphological parameters were studied in two marine gastropods to better define niche differences between the species. M. turbiformis is adapted to a broader more variable niche where as M. turbinata has more stringent niche requirements. This study demonstrated that M. turbinata as compared with M. turbiformis has: a) greater foot muscle strength, b) shorter more squat shell form, c) greater body weight per shell weight and d) greater foot size per body weight. M. turbiformis has a) greater resistance to desiccation and low temperature and b) a more slender shell form. Qualitatively, M. turbiformis appears less effected by elevated temperatures to 40° C. In the laboratory, M. turbinata is more sensitive to crowding. In the field, M. turbinata is found principally in high energy situations with respect to surf action or water flow on or over rocks to which it is attached. On the other hand, M. turbiformis is exclusively found in relatively quiet, shallow water, behind barriers protected from all but the most violent sea action. These data and observations are consistent with M. turbiformis being adapted to a niche with greater extremes with respect to temperature, desiccation and possibly oxygen and metabolic waste product levels. M. turbinata, in part due to its foot muscle strength and shell morphology, is adapted to a high energy niche which would be less varied with respect to the parameters described.

Oxygen isotopes from Phorcus (Osilinus) turbinatus shells as a proxy for sea surface temperature in the central Mediterranean: A case study from Malta

“…P, turbinatus has been observed in rock pools lower on the shoreline that are regularly flushed out by tides and not sub aerially exposed for long periods. They do not tend to inhabit rock pools in the uppermost intertidal zone (Menzies et al, 1992 and author's observation). When P. turbinatus are found with other species of Phorcus/Osilinus, P. turbinatus inhabit the mid to lower intertidal zone whilst other species are found in the upper intertidal zone (Menzies et al, 1992).…”

“…They do not tend to inhabit rock pools in the uppermost intertidal zone (Menzies et al, 1992 and author's observation). When P. turbinatus are found with other species of Phorcus/Osilinus, P. turbinatus inhabit the mid to lower intertidal zone whilst other species are found in the upper intertidal zone (Menzies et al, 1992). In addition, P. turbinatus are relatively mobile and have been observed to move considerable distances along the shoreline as they forage (Crothers, 2001).…”

“…P. turbinatus ecology and distribution P. turbinatus (von Born, 1788), previously known as Osilinus turbinatus, Monodonta turbinata and Trochocochlea turbinatus (Donald et al, 2012), is a rocky shore intertidal gastropod found throughout the eastern and western Mediterranean basins (Menzies et al, 1992;Crothers, 2001). The gastropod is found on all but the most exposed of Malta's shores in the mid to lower intertidal zone (Schembri et al, 2005).…”

“…The gastropod is found on all but the most exposed of Malta's shores in the mid to lower intertidal zone (Schembri et al, 2005). P. turbinatus has a lower tolerance for variations in temperature and salinity than other species of Osilinus and Phorcus in the Mediterranean (Menzies et al, 1992). The possibility that P. turbinatus may be exposed to intertidal microenvironments where temperatures, salinities and seawater stable isotope compositions fluctuate beyond that of well mixed seawater cannot be completely discounted.…”

“…The possibility that P. turbinatus may be exposed to intertidal microenvironments where temperatures, salinities and seawater stable isotope compositions fluctuate beyond that of well mixed seawater cannot be completely discounted. However, field and laboratory observations have shown that the species has a strong foot muscle that allows it to occupy high energy shorelines where daily changes in temperature, oxygen and salinity are minimal (Menzies et al, 1992;Benedetti-Cecchi et al, 2003). P, turbinatus has been observed in rock pools lower on the shoreline that are regularly flushed out by tides and not sub aerially exposed for long periods.…”