Batzina Alkisti, Dalla Christina, Papadopoulou-Daifoti Zeta, Karakatsouli Nafsika
Department of Applied Hydrobiology, Faculty of Animal Science and Aquaculture, Agricultural University of Athens, Iera Odos 75, 118 55 Athens, Greece.
Department of Pharmacology, Medical School, University of Athens, Mikras Asias 75, 115 27 Goudi, Athens, Greece.
Comp Biochem Physiol A Mol Integr Physiol. 2014 Mar;169:25-32. doi: 10.1016/j.cbpa.2013.12.001. Epub 2013 Dec 8.
The presence of blue or red-brown substrate on the tank bottom has been previously reported as an efficient means of environmental enrichment for gilthead seabream. The present study aimed to investigate whether this enrichment is still beneficial when gilthead seabream is reared under different social conditions (i.e. a lower 4.9 kg m(-3) and a higher 9.7 kg m(-3) density). Water exchange was adjusted according to fish biomass to exclude density effects on water quality. In the enriched tanks single-colour glass gravel was used as substrate (blue and red-brown substrate, or BS and RBS respectively), while control tanks had no gravel. Growth, aggressive behaviour and size distribution results indicated that the lower density created a less favourable social environment. In both densities studied, BS enhanced growth, suppressed aggression and reduced brain serotonergic activity. In the condition of intense social interactions (i.e. the lower density) BS also reduced brain dopaminergic activity. These results along with the negative correlations observed between brain monoamines and fish body mass, indicated that substrate and density effects are socially-induced. However, there may be several biotic and/or abiotic factors interfering with substrate effects that should be investigated before the practical use of a substrate in land-based intensive aquaculture.
此前已有报道称，在养殖池中底部存在蓝色或红棕色底质是一种有效的促进金头鲷环境富集的方法。本研究旨在调查当金头鲷在不同养殖密度（即较低的4.9千克/立方米和较高的9.7千克/立方米）的不同社会条件下养殖时，这种富集方式是否仍然有益。根据鱼的生物量调整换水频率，以排除密度对水质的影响。在添加了富集物的养殖池中，使用单色玻璃砾石作为底质（分别为蓝色和红棕色底质，即BS和RBS），而对照池中没有砾石。生长、攻击行为和大小分布结果表明，较低密度营造了一个不太有利的社会环境。在所研究的两种密度条件下，蓝色底质均促进了生长、抑制了攻击行为并降低了大脑血清素能活性。在社会互动激烈的条件下（即较低密度），蓝色底质还降低了大脑多巴胺能活性。这些结果以及在大脑单胺与鱼体质量之间观察到的负相关关系表明，底质和密度效应是由社会因素引起的。然而，在陆基集约化水产养殖实际使用底质之前，可能有几种生物和/或非生物因素干扰底质效应，对此应进行调查。
