Forrester Graham E
Marine Sciences Institute, University of California, 93106, Santa Barbara, CA, USA.
Department of Biological Sciences, University of California, 93106, Santa Barbara, CA, USA.
Oecologia. 1995 Aug;103(3):275-282. doi: 10.1007/BF00328615.
Debate on the control of population dynamics in reef fishes has centred on whether patterns in abundance are determined by the supply of planktonic recruits, or by post-recruitment processes. Recruitment limitation implies little or no regulation of the reef-associated population, and is supported by several experimental studies that failed to detect density dependence. Previous manipulations of population density have, however, focused on juveniles, and there have been no tests for density-dependent interactions among adult reef fishes. I tested for population regulation in Coryphopterus glaucofraenum, a small, short-lived goby that is common in the Caribbean. Adult density was manipulated on artificial reefs and adults were also monitored on reefs where they varied in density naturally. Survival of adult gobies showed a strong inverse relationship with their initial density across a realistic range of densities. Individually marked gobies, however, grew at similar rates across all densities, suggesting that density-dependent survival was not associated with depressed growth, and so may result from predation or parasitism rather than from food shortage. Like adult survival, the accumulation of new recruits on reefs was also much lower at high adult densities than at low densities. Suppression of recruitment by adults may occur because adults cause either reduced larval settlement or reduced early post-settlement survival. In summary, this study has documented a previously unrecorded regulatory mechanism for reef fish populations (density-dependent adult mortality) and provided a particularly strong example of a well-established mechanism (density-dependent recruitment). In combination, these two compensatory mechanisms have the potential to strongly regulate the abundance of this species, and rule out the control of abundance by the supply of recruits.
关于珊瑚礁鱼类种群动态控制的争论主要集中在种群数量模式是由浮游幼鱼的补充供应决定，还是由补充后的过程决定。补充限制意味着对与珊瑚礁相关的种群几乎没有或没有调节作用，并且得到了几项未能检测到密度依赖性的实验研究的支持。然而，以前对种群密度的操纵主要集中在幼鱼身上，对于成年珊瑚礁鱼类之间的密度依赖性相互作用还没有进行过测试。我对一种小型、寿命短的虾虎鱼——灰鳍虾虎鱼（Coryphopterus glaucofraenum）进行了种群调节测试，这种虾虎鱼在加勒比地区很常见。在人工鱼礁上操纵成年虾虎鱼的密度，同时也在自然密度不同的鱼礁上对成年虾虎鱼进行监测。在实际的密度范围内，成年虾虎鱼的存活率与其初始密度呈现出强烈的负相关关系。然而，个体标记的虾虎鱼在所有密度下的生长速度相似，这表明密度依赖性存活与生长受抑制无关，因此可能是由捕食或寄生而非食物短缺导致的。与成年虾虎鱼的存活情况类似，在成年密度高时，鱼礁上新补充幼鱼的积累量也比低密度时低得多。成年鱼对补充的抑制可能是因为成年鱼导致幼体着床减少或着床后早期存活率降低。总之，本研究记录了一种以前未记录的珊瑚礁鱼类种群调节机制（密度依赖性成年鱼死亡率），并提供了一个既定机制（密度依赖性补充）的特别有力的例子。这两种补偿机制结合起来，有可能强有力地调节该物种的数量，并排除了幼鱼补充供应对数量的控制。
