Mol Jan H
CELOS, University of Suriname, P.O.B. 9212, Paramaribo, Suriname.
Oecologia. 1996 Aug;107(3):395-410. doi: 10.1007/BF00328457.
This study investigated the role of predators in preventing competitive exclusion among three closely related armoured catfishes (Callichthys callichthys, Hoplosternum littorale and H. thoracatum) that occur synthopically in multi-predator freshwater swamps of Suriname, South America. The potential impact of predation on armoured catfish was determined by combining laboratory measurements of predation rates on five early developmental stages of the armoured catfish H. thoracatum for 24 aquatic predators with field studies of the density of the predators in the swamps. The contribution of a particular predator to the total predation pressure on its prey was determined to a large extent by the density of the predator in the swamp. Seemingly innocuous predators with low or moderate predation rates in the laboratory may be extremely important in the swamps due to their high abundance. Small-sized omnivorous fishes and aquatic invertebrates were major predators of early developmental stages of armoured catfish. Both qualitative and quantitative ontogenetic changes in the predation pressure on armoured catfish were observed. Major predation on eggs, larvae and juveniles of H. thoracatum resulted from a different set of predators in each developmental stage of the prey. In all developmental stages of H. thoracatum the predation pressure involved several predator species and not a single, dominant predator. The potential predation pressure of the 24 predators taken together and the number of predators that were able to prey on H. thoracatum decreased sharply with increasing age (size) of the prey. Even if egg (nest) predation is prevented by the guarding male, the potential impact of the 24 predators on the populations of armoured catfish is large. Predation may account for the high mortality of H. thoracatum observed in the swamps. The high predation pressure on callichthyid catfishes may help to explain the coexistence of three closely related and morphologically quite similar armoured catfishes in Surinamese swamps.
本研究调查了在南美洲苏里南多捕食者的淡水沼泽中同域分布的三种近缘甲鲶（硬鳞甲鲶、饰纹兵鲶和胸饰纹兵鲶）中，捕食者在防止竞争排斥方面所起的作用。通过结合对甲鲶胸饰纹兵鲶五个早期发育阶段的24种水生捕食者的捕食率进行实验室测量，以及对沼泽中捕食者密度的实地研究，来确定捕食对甲鲶的潜在影响。特定捕食者对其猎物总捕食压力的贡献在很大程度上取决于该捕食者在沼泽中的密度。在实验室中捕食率较低或适中的看似无害的捕食者，由于其数量众多，在沼泽中可能极为重要。小型杂食性鱼类和水生无脊椎动物是甲鲶早期发育阶段的主要捕食者。观察到甲鲶捕食压力在定性和定量方面均存在个体发育变化。胸饰纹兵鲶的卵、幼体和成体的主要捕食者在猎物的每个发育阶段都有所不同。在胸饰纹兵鲶的所有发育阶段，捕食压力涉及多种捕食者物种，而非单一的优势捕食者。随着猎物年龄（体型）的增加，24种捕食者共同构成的潜在捕食压力以及能够捕食胸饰纹兵鲶的捕食者数量急剧下降。即使有护卵雄鱼防止卵（巢）被捕食，这24种捕食者对甲鲶种群的潜在影响仍然很大。捕食可能是沼泽中观察到的胸饰纹兵鲶高死亡率的原因。对甲鲶科鲶鱼的高捕食压力可能有助于解释苏里南沼泽中三种近缘且形态颇为相似的甲鲶为何能够共存。
