An Investigation Into the Seasonality and Quality of Food on Marina Pontoon Structures for the Candidate Marine Biological Control Agent, Lunella smaragda (Gastropoda)

Abstract

This study investigates how food availability aligns with nutritional requirements of the snail Lunella smaragda , a potential biological control agent for managing biofouling in recreational vessel hubs. Biofouling communities were assessed during two contrasting seasons to gain insights into the quantity and quality of food available for agent consumption. Nutritional availability was higher in spring/summer and increased with biofouling age, whereas the increase plateaued after 32 days of the 54‐day deployment period in autumn/winter. Biofouling communities were predominantly composed of saturated fatty acids, with proportions of polyunsaturated and monounsaturated fatty acids varying between seasons. In the laboratory, snails were exposed to one of three feeding scenarios over a 7‐day period (nil, low and high food) and changes in physiological condition (i.e., protein, lipid, carbohydrate content and malondialdehyde levels) were evaluated. Short‐term food limitation resulted in a marginally significant decrease in protein and increase in wet weight for snails on a high food diet, when compared to other treatments. When compared to baseline data, lipid content significantly decreased across all treatments, while protein and water content in the nil and low food treatments and wet weight in the high food treatment increased significantly. Malondialdehyde levels were lower in the nil and low food treatments, while increasing in snails fed the high food diet, indicating a higher metabolic response in well‐fed snails. These results suggest that alternative management strategies, such as adjusting grazing density and providing supplemental feed, may be required to prevent starvation and maintain treatment efficiency during periods of poor food availability.

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