Pekcan-Hekim Zeynep, Lappalainen Jyrki
Department of Biological and Environmental Sciences/Aquatic Sciences, University of Helsinki, P.O. Box 65, FI-00014, University of Helsinki, Finland.
Naturwissenschaften. 2006 Jul;93(7):356-9. doi: 10.1007/s00114-006-0114-1. Epub 2006 Apr 8.
Increased turbidity reduces visibility in the water column, which can negatively affect vision-oriented fish and their ability to detect prey. Young fish could consequently benefit from high turbidity levels that can provide a protective cover, reducing predation pressure. Perch (Perca fluviatilis) are commonly found in littoral zones of temperate lakes and coastal areas of the Baltic Sea. Pikeperch (Sander lucioperca) spawn in these areas, so perch is a potential predator for pikeperch larvae. We conducted laboratory experiments to test the predation of perch on pikeperch larvae at different turbidity levels (5-85 nephelometric turbidity units), densities of pikeperch larvae (2-21 individuals l(-1)) and volumes of water (10-45 l). The logistic regression showed that the probability of larvae eaten depended significantly on turbidity and volume of water in the bags, while density of larvae was not significant. However, because container size is known to affect predation, the data was divided into two groups based on water volume (10-20 and 25-45 l) to reduce the effects of container size. In either group, probability of predation did not significantly depend on volume, whereas turbidity was significant in both groups, while density was significant in larger water volumes. Thus, high turbidity impaired perch predation and protected pikeperch larvae from perch predation. Because density of larvae was also a significant factor affecting predation of perch, the dispersal of pikeperch larvae from spawning areas should also increase the survival of larvae.
水体浊度增加会降低水柱中的能见度，这可能会对依靠视觉捕食的鱼类及其探测猎物的能力产生负面影响。因此，幼鱼可能会受益于高浊度水平，因为这可以提供保护屏障，降低被捕食的压力。鲈鱼（河鲈）常见于温带湖泊的沿岸带和波罗的海的沿海地区。梭鲈在这些区域产卵，所以鲈鱼是梭鲈幼鱼的潜在捕食者。我们进行了实验室实验，以测试在不同浊度水平（5 - 85 散射浊度单位）、梭鲈幼鱼密度（2 - 21 尾/升）和水量（10 - 45 升）条件下，鲈鱼对梭鲈幼鱼的捕食情况。逻辑回归分析表明，幼鱼被吃掉的概率显著取决于袋子中的浊度和水量，而幼鱼密度并无显著影响。然而，由于已知容器大小会影响捕食行为，因此根据水量（10 - 20 升和 25 - 45 升）将数据分为两组，以减少容器大小的影响。在任何一组中，捕食概率都不显著取决于水量，而浊度在两组中均具有显著影响，在较大水量组中幼鱼密度也具有显著影响。因此，高浊度会削弱鲈鱼的捕食能力，保护梭鲈幼鱼免受鲈鱼捕食。由于幼鱼密度也是影响鲈鱼捕食的一个重要因素，梭鲈幼鱼从产卵区扩散也应能提高幼鱼的存活率。
