真刺唇角水蚤对鱼卵和仔鱼的捕食

PREDATION ON FISH EGGS AND LARVAE BY LABIDOCERA EUCHAETA

鱼类幼体的死亡常常被归因于食物的缺乏,实际上,以桡足类为主的浮游动物对鱼卵和仔鱼的捕食是其死亡的最主要原因之一,也是影响鱼类资源补充的主要因素;所以,研究桡足类对鱼卵和仔鱼的捕食不仅对海洋食物链研究而且对研究鱼类资源补充和产量的估算,也具有重要的意义。有关这方面的实验国内尚未见专门报道。

Predation on fish eggs and larvae by copepods is investigated at Xiamen Harbour during April to June, 1987. Labidocera euchaeta, a dominant copepod weighing 0.11mg for females and 0.06mg for males, is used as predator, and eggs and arvae of Spams macrocephalus (egg diameter 0.95mm, larva length 2.40mm) and Boleophthalmus pectinirostris (egg diameter 0.92-1.26mm, dry weight 30.7μg; larva length 2.52-2.63mm, dry weight 19.1μg) are used as foods. The daily ingestion rate of adult L. euchaeta is 2.0-7.0 eggs and 5.5-7.5 larvae of S. macrocephalus or 1.3-5.9 eggs and 0.2-3.6 larvae of B. pectinirostris, equivalent to 96.8-215.5% body dry weight of copepod. The ingestion rate increases [0.2-5.9 eggs or lar-vae/(cop·d)] with the increasing of the density of fish eggs or larvae (0.04-0.20 egg or larva/ml). When L. euchaeta was fed with fish eggs and larvae as well as Anemia nauplii (as an additional food), its ingestion rate on fish eggs and larvae was lowered although it ingested more of fish eggs and larvae than of Anemia nauplii. This is because of its lower feeding efficiency on much smaller-sized food as Arte mia nauplii. Coatal and estuarine copepods often occur abundantly during the fish propagation period at Xiamen Harbour, and thus are likely to be the main predators of fish eggs and larvae. It is suggested that carnivorous and some omnivorous copepods be eliminated before fish eggs and larvae are laid into culture ponds.