Change in tenacity of limpet Cellana tramoserica in response to holding scenarios and diesel WAF

Limpets are sensitive intertidal molluscs that require sufficient substrata area for locomotion and to maintain tenacity. Tenacity is the ability of a limpet to attach to a substrate. Maintaining tenacity is vitally important for protection against predatory attacks and resistance to crashing waves. In this study Cellana tramoserica in the field exhibited an average tenacity of 311.04 Newtons, which is equivalent to 31.16 kg. For an animal weighing on average 11.46 grams (wet weight), this field tenacity represents a Newton force of 2719.57 times the animal’s own body mass. In the laboratory limpets were held within three different holding designs to identify the most effective 24-hour holding scenario for maintaining tenacity, and to maximise replicate numbers. Tenacity was measured as the upward force required to lift the attached limpet from the substrate. Tenacity was greatly reduced when the animals were confined to a small substrate area either within metal cages or a beaker. Bubbles formed under the pedal sole during re-attachment, significantly inhibiting tenacity capability as there was limited area for locomotion to expel trapped bubbles.Limpet tenacity can also be compromised by oil from marine fuel spills, including diesel water accommodated fraction (WAF). Diesel WAF is the aqueous solution that forms when oil and water are mixed, resulting in the dissolved components forming a WAF. Cellana tramoserica tenacity decreased, and histological alteration in digestive gland tubules and some parts of the foot increased when exposed to increasing concentrations of diesel WAF. Following the ANZECC marine water quality guidelines principles, it is estimated that a protective diesel WAF concentration over a 24 hour duration would need to be below 1.95% to prevent a 10% reduction in tenacity across the exposed limpet population, and below 14.79% to prevent a 50% reduction in tenacity across the population.