四十里湾几种双壳贝类及污损动物的氮、磷排泄及其生态效应

对多种经济双壳贝类和养殖中的污损动物的N和P排泄进行了测定 ,包括排泄成分和排泄速率。在这些动物的N排泄中 ,NH4 N占主要部分 ,如笼式养殖的双壳贝类NH4 N占总N排泄的平均值范围为 70 8%— 80 1 % ;氨基酸是第二大排泄成分 ,平均占总N排泄的 1 0 %—2 5 %。其他形态的N ,如尿素、亚硝酸盐和硝酸盐也有检出。在P排泄中 ,有机磷 (DOP)约占总溶解磷 (TDP)排泄的 1 5 %— 2 7%。据估算 ,整个四十里湾所养殖的双壳贝类在夏季每天将排泄4 5 4t总溶解氮 ,其中NH4 N 3 36t、Amino N 0 69t、Urea N 0 2t。同时每天磷的排泄为 0 5 7tTDP ,其中DOP 0 1 5t。对面积为 1 3× 1 0 4 hm2 的海区而言 ,贝类的N、P排泄分别能满足浮游植物生产所需N、P的 44%和 40 %。高密度的贝类养殖对养殖生态系统营养循环的影响是很显著的。附着动物 (柄海鞘等 )的N、P排泄及其对营养循环的影响也不容忽视。

NITROGEN AND PHOSPHORUS EXCRETION AND ITS ECOLOGICAL EFFECT BY SEVERAL BIVALVES AND FOULING ANIMALS

Nitrogen and phosphorus excretion by several filter feeding mollusks, including Chlamys farreri, Argopecten irradians, Mytilus edulis, Crassostrea gigas, Ruditapes philippinarum and fouling organisms(Styela clave, Ciona intestinalis, Balanus amphitrite and Trapezium liratum ) collected from coastal culture areas, were studied NH₄-N was the predominant nitrogenous excretory product, which accounted for more than 70% (mean 70.8%-80.1% ) of TN excreted by these organisms. Amino acids are the second main nitrogenous component excreted by all of the studied organisms, which constituted 10%-25% of TN product. Other nitrogenous components excreted by the species were urea, nitrite and nitrate, but no significant amount of uric acid was measured in these bivalve species. Organic phosphorus constituted 15%-27% of the total phosphorus excreted by these organisms. The calculated everyday excretion rates of N and P of all raft cultured bivalves in Sishili Bay in summer could provide 44% an d 40% respectively of N and P demands for pelagic primary production. The raft cultured bivalves played an important role in nutrient regeneration in a coastal aquaculture ecosystem.