污损生物对大亚湾养殖珍珠贝的滤食、呼吸和排泄的影响

污损生物是影响贝类养殖业生产效率的重要因素。污损生物不仅附着在养殖网笼上,而且也大量附着在养殖生物的贝壳上。大部分污损生物是滤食性捕食者,这些污损生物与养殖生物竞争食物,氧气与空间导致贝类生长速度减慢,死亡率提高。本实验以大亚湾养殖网笼里的珍珠贝及附着的污损生物为对象,研究有污损生物附着的珍珠贝及没有污损附着的珍珠贝在滤食,耗氧及排泄上的差异,同时对网笼上附着的污损生物优势种的滤食,呼吸及排泄也进行了测定,用以说明污损生物对养殖生物滤食,耗氧和排泄的影响。研究结果表明,有污损附着的珍珠贝及没有污损附着的珍珠贝在滤食率,耗氧率和氮磷排泄率上存在明显差异,有污损附着的珍珠贝的滤食率,NH4-N和PO4-P的排泄率要高于没有污损附着的珍珠贝。同时在网笼上附着的优势污损生物的滤食,耗氧和排泄也不容忽视,他们对食物的滤食,溶氧的消耗及氮磷排泄的贡献也很大。本研究结果表明,不管是附着在养殖生物贝壳上还是附着在网笼上的污损生物与养殖生物之间存在食物及氧气的竞争,污损生物对水中氮、磷浓度的提高贡献也很大,因此在养殖中,污损生物的影响不容忽视。

Effect of Fouling on Feeding, Oxygen Consumption and Waste Excretion of Pearl Oyster Pinctada martensii in Daya Bay Cultivation

Biofouling is a particular problem in the pearl oyster culture. It may reduce the growth and survival rates of the cultured species. Foulers are often themselves filter feeders, and are therefore potential competitors for food resource with the cultured species. Fouling organisms may also reduce the oxygen supply. A study was conducted to measure the impact of foulers on feeding, oxygen consumption, and waste excretion. POM, ammonia, phosphate and oxygen concentration were measured in various treatments (cultured species,foulers). This study showed that fouling organisms had significant effect on food uptake, oxygen consumption and waste excretion. The clearance rate, ammonia and phosphate release rate, oxygen consumption rate of the fouled pearl oyster were greater than those of the clean pearl oysters. Other foulers that settled on cages or buoys also contributed much to phytoplankton depletion, oxygen consumption and concentration increase of ammonia and phosphate in water. Therefore, this study showed us that foulers were important competitors in the pearl oyster cultivation of Daya Bay in November 2005.