Quantitative aspects of the food of Littorina Littorea (Linnaeus)

Murphy, Francis Edmund (1974) Quantitative aspects of the food of Littorina Littorea (Linnaeus). Masters thesis, Memorial University of Newfoundland.

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Abstract

Two series of feeding experiments were carried out on Littorina littorea, each using three groups of 33 snails. At Bonne Bay, each group was fed one of Ascophyllum nodosum, Fucus vesiculosus, and Lami'naria longicruris. Algae used at Logy Bay were the same, except that the third was Laminaria digitata. Controls were of two kinds. An initial group of 33 was measured and weighed, then killed to obtain dry weights, caloric content and ash content. The second control was a group of 100 marked snails, weighed and measured, then released upon the shore. At the end of six weeks, 15 of these were recovered alive. Data and discussion are provided for the 13 identifiable snails. -- The experimental animals were marked, weighed and measured. During six weeks, record was kept of the amount of food ingested and the amount of feces produced. At the end of the experiment, animals were again measured and weighed; they were then killed to obtain dry weights, caloric content and ash content. -- The results generally show a decrease in all measurements. Shell length remained unchanged in four groups, increased slightly (but significantly) in two. Wet weights decreased in four groups, significantly in one, and increased in two groups, significantly in one. 'Dry weight decreased in all groups, significantly in two. Highly significant decreases in caloric content occurred in all six groups. With other factors considered, the Bonne Bay Laminaria group showed a gain in caloric content. Factors causing this gain are discussed. -- Lack of growth is considered to be due to conditions of captivity, natural periods of decrease in growth, and especially to the probable unsuitability of the algae used as food.

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