Williams Ivor D, Baum Julia K, Heenan Adel, Hanson Katharine M, Nadon Marc O, Brainard Russell E
Coral Reef Ecosystem Division, Pacific Islands Fisheries Science Center, National Oceanographic and Atmospheric Administration, Honolulu, Hawaii, United States of America.
Department of Biology, University of Victoria, Victoria, British Columbia, Canada.
PLoS One. 2015 Apr 1;10(4):e0120516. doi: 10.1371/journal.pone.0120516. eCollection 2015.
Coral reefs around US- and US-affiliated Pacific islands and atolls span wide oceanographic gradients and levels of human impact. Here we examine the relative influence of these factors on coral reef fish biomass, using data from a consistent large-scale ecosystem monitoring program conducted by scientific divers over the course of >2,000 hours of underwater observation at 1,934 sites, across ~40 islands and atolls. Consistent with previous smaller-scale studies, our results show sharp declines in reef fish biomass at relatively low human population density, followed by more gradual declines as human population density increased further. Adjusting for other factors, the highest levels of oceanic productivity among our study locations were associated with more than double the biomass of reef fishes (including ~4 times the biomass of planktivores and piscivores) compared to islands with lowest oceanic productivity. Our results emphasize that coral reef areas do not all have equal ability to sustain large reef fish stocks, and that what is natural varies significantly amongst locations. Comparisons of biomass estimates derived from visual surveys with predicted biomass in the absence of humans indicated that total reef fish biomass was depleted by 61% to 69% at populated islands in the Mariana Archipelago; by 20% to 78% in the Main Hawaiian islands; and by 21% to 56% in American Samoa.
美国及其附属太平洋岛屿和环礁周围的珊瑚礁跨越了广泛的海洋学梯度和人类影响水平。在这里，我们利用科学潜水员在1934个地点进行的超过2000小时水下观测的数据，这些地点分布在约40个岛屿和环礁上，来自一个持续的大规模生态系统监测项目，来研究这些因素对珊瑚礁鱼类生物量的相对影响。与之前较小规模的研究一致，我们的结果表明，在相对较低的人口密度下，礁鱼生物量急剧下降，随着人口密度进一步增加，下降趋势更为平缓。在考虑其他因素后，我们研究地点中海洋生产力最高的地区，其礁鱼生物量（包括浮游生物食性鱼类和食鱼性鱼类生物量的约4倍）是海洋生产力最低岛屿的两倍多。我们的结果强调，珊瑚礁区域维持大型礁鱼种群的能力并非都相同，而且不同地点的自然状况差异很大。将目视调查得出的生物量估计值与无人为干扰情况下的预测生物量进行比较表明，在马里亚纳群岛有人居住的岛屿上，礁鱼总生物量减少了61%至69%；在夏威夷主要岛屿上减少了20%至78%；在美属萨摩亚减少了21%至56%。
