墨西哥湾扇贝稚贝对盐度的耐受力

Salinity tolerance of the southern bay scallop Argopecten irradians concentricus

用壳高１５～２１ｍｍ的墨西哥湾扇贝（Ａｒｇｏｐｅｃｔｅｎ ｉｒｒａｄｉａｎｓ ｃｏｎｃｅｎｔｒｉｃｕｓ）稚贝作为实验材料，控制水温在１６和２４℃条件下进行对盐度的耐受力实验．实验结果表明，当温度在２４℃时，稚贝存活的盐度范围为１８．５～４４．４，低盐度对稚贝的存活影响明显．稚贝可生长的盐度范围是２１．２～４１．０（日增长率ｒ＞４．０），适宜的生长盐度为２４．０～３２．０（日增长率ｒ＞８．０），其中２６．０～２８．０的盐度为最佳生长盐度。在１６℃条件下，最初８ｈ内，其生存盐度范围为１７．４～４６．４，但是４８ｈ后稚贝的存活盐度范围与２４℃温度条件时无明显差别，显示出低温条件会使稚贝对极限盐度的反应速率减缓．当盐度处于接近极限范围时，盐度变化幅度过大易导致稚贝死亡．墨西哥湾扇贝对盐度的适应能力与原生境盐度有关，稚贝预先在盐度为１９．５和４４．９中适应９ｄ后，再过度到１４．３和４８．５中，４８ｈ后，存活率为７８．３％和１００％，而若是从盐度为３２中直接移到３和４８．５中，４８ｈ后存活率分别为０和２７．３％．显然，通过中间驯化或适应过程，稚贝会提高耐盐能力．此结果表明，在高温多雨的南方海域，应避免在易受淡水中冲击?

The range of salinity tolerance of the southern bay scallop. A. irradians concentrycus was studied in laboratory. All experi ments were carried out with the spats, 15～21 mm in height, by exposing the spats to various salinities for periods of 48 h or more, with theaim of explaining the observations about the mortality in nature and deciding the farming sites for this species culture. The survival range ofsalinity is 18.5～44.4 at 16 and 24℃. The effect of lowerr salinity on the survival rate is more obvious. The salinity range for growth of thespats is 21.2～41.0 (the drily growth rate, r>4.0), suitable 24.0～32.0 (r>8), and optimal 26.0～28.0. If the salinity fluctuatesstrongly, the survival rate decreases seriously when the salinity is close to threshold value. The salinity tolerance of the scallop relates ot theenvironmental salinity, too. The species is more resistant to salinity vacriation at decreasing temperature in a sbort time, but cannot increaseits tolerance range in the lasting time. Results show that the species can survive and normally grow in the southern china seaarea, but it isunsuitable to planting in the estuary or the farming areas where the scallops may expose to freshwater.