從台灣產雜斑蓮花青螺Lottia luchuana (Pilsbry, 1901)之族群動態、生態生理與活動型態探討台灣潮間帶貝類的壓力適應

Abstract

Intertidal species face many environmental stresses. In the intertidal environment, species live close to the habitats which fit their physiological limits. Physical stress, therefore, severely affects the survival of intertidal organisms. At present, little is known about ecophysiology of intertidal species in Taiwan coast. The intertidal limpet Lottia luchuana is widely distributed on the mid and high shores in north-eastern and eastern coasts of Taiwan. The intense heat and desiccation in summer and heavy rain in winter can impose serious physiological stress to affect the survival, sublethal response and behavior of the limpets. An integrated approach to understand the population dynamics, osmotic regulation and activity pattern of L. luchuana is essential to study how the limpets can adapt to the stressful environments in the intertidal. In this study, we investigated the population dynamics of L. luchuana for two years on the eastern and north-eastern shores of Taiwan, to see the pattern of life history under such stressful environment. In addition, we conducted a series of osmolality examinations of the haemolymph and mantle water of L. luchuana under different weather conditions, both in summer and winter, and investigated the diurnal, spring-neap tide, and seasonal activity pattern on north-eastern coast. Results indicated L. luchuana presented good ability in adaptation for stressful intertidal both in population and individual levels. In population level, L. luchuana exhibits seasonal shift of vertical distribution to reduce physical stresses. The juvenile recruits during Dec. to Mar. on eastern coasts, with low mortality and high growth rate. In north-eastern shores, the new recruitments exhibit in summer and winter respectively, and the population density of adults decline after summer season. In individual level, results showed there is a high correlation in mantle and haemolymph osmolality in benign conditions. However, under heavy rain and intense solar radiation, haemolymph seems to be more constant than mantle. It is likely that there is an osmotic regulation in haemolymph to tolerate the environmental stress on L. luchuana. Also, we found that the limpets stay stationary in most of the time and the activity is only stimulated by tide and wave awash. Limpets did not follow a vertical movement with the rising and ebbing tides. This study shows L. luchuana adapt well to live in mid-high shore of the intertidal and demonstrate good environmental tolerance by physiological and behavioral regulation.