Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
Mar Environ Res. 2011 Oct;72(4):160-71. doi: 10.1016/j.marenvres.2011.07.005. Epub 2011 Aug 11.
We have investigated temporal variability in the quantity and biochemical composition of sediment organic matter along with variables proxies of water eutrophication (e.g., inorganic nutrient and chlorophyll-a) at two shrimp farms located in the Southern coast of New Caledonia and characterised by clear differences in shrimp feeding practices and levels of initial trophic conditions. The results of our study reveal that the trophic status of the water column increased during the rearing cycle at both sites, determining a general, though moderated, eutrophication. However, the water column trophic descriptors did not allow to discriminate differences in the trophic status among the investigated sites or between sites in the same farming plant, even if they were subjected to different feeding practices and largely different initial characteristics of the sediment. Temporal variations in biopolymeric C and phytopigment sedimentary contents (used as proxies of benthic eutrophication) varied inconsistently among sites. The multivariate analyses did not identify significant temporal patterns in the benthic trophic status, but allowed discriminating the four investigated sites. The semi-intensive shrimp farming significantly contributed to changing the water column and sediments trophic status of the earthen ponds, but the extent of those changes was not consistently observed in all ponds. In any of the investigated ponds the trophic status exceeded concerning thresholds over which hypoxia or anoxia could occur. We conclude that the established semi-intensive practices adopted so far for shrimp farming activities in the earthen ponds of New Caledonia are able to maintain the status of the ponds below the eutrophication levels over which dystrophic crises could sharply abate most of the reared biomass.
我们调查了新喀里多尼亚南部两个虾养殖场的沉积物有机质数量和生化组成的时间变化，以及水富营养化的变量代用指标（例如无机养分和叶绿素-a），这两个虾养殖场的虾养殖方式和初始营养条件水平存在明显差异。我们的研究结果表明，在两个地点的养殖周期中，水柱的营养状况都有所增加，导致普遍但适度的富营养化。然而，水柱营养描述符无法区分调查地点之间或同一养殖厂内不同地点之间的营养状况差异，即使它们采用不同的投喂方式，且沉积物的初始特征也大不相同。生物聚合碳和浮游植物色素沉积物含量（用作底栖富营养化的代用指标）的时间变化在各地点之间不一致。多元分析并未确定底栖营养状况的显著时间模式，但允许区分四个调查地点。半集约化虾养殖显著改变了土池的水柱和沉积物的营养状况，但并非所有池塘都观察到这些变化的程度一致。在任何调查的池塘中，营养状况都超过了可能发生缺氧或缺氧的临界阈值。我们得出结论，迄今为止，新喀里多尼亚土池虾养殖中采用的半集约化实践能够将池塘的状况维持在富营养化水平以下，在这种水平上，营养不良危机可能会急剧减少大部分养殖生物量。
