Differences in fish-assemblage structure between fished and unfished atolls in the northern Line Islands, central Pacific
Differences in fish-assemblage structure between fished and unfished atolls in the northern Line Islands, central Pacific
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DOI：
10.3354/meps07501
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发表时间：
2008-01-01
影响因子：
2.5
通讯作者：
Sala, Enric
中科院分区：
文献类型：
--
作者：
DeMartini, Edward E.;Friedlander, Alan M.;Sala, Enric
我们描述了莱恩群岛北部2个美国太平洋环礁(Kingman，Palmyra)和2个基里巴斯拥有的环礁(Tabuairan，Kiritimati)的浅礁前生境(10米深)的鱼类组合的丰度、生物量、大小组成和营养结构。我们的描述跨越了几个重合的梯度(在人类的居住和开发、纬度和营养物质的上升)，从无人居住的、目前没有捕捞的和营养稀少的Kingman到相对密集的、捕捞的和赤道上涌的Kiritimati。主要发现与提取对大型捕食者的直接影响和对低层群落结构的间接影响最为一致。巴尔米拉，特别是金曼环礁的鱼类群落的特点是总现存量高，平均体型大，顶端捕食者和其他食鱼性鱼类在生物量倒置的金字塔中占优势，少数小型浮游性鱼类，以及以非领土物种为主的草食性鱼类。在Kingman和Palmyra的4种鹦鹉鱼中，从初始到末期颜色变化(鹦鹉鱼性别变化的一个指标)的中位数身体大小也很小。塔布阿兰环礁，特别是基里蒂马蒂环礁的鱼类组合具有截然不同的特征：以鱼类和其他渔业为目标的鱼类数量减少，低营养层控制鱼类生物量，浮游性鱼类为Targer体型且数量更多，更好地代表了地域性草食动物，鹦鹉鱼成熟时的大小比例较大。我们的结果表明，即使是适度的捕捞活动也可能对组合结构产生影响，并表明像Kingman这样的珊瑚礁作为日益稀有的天然珊瑚礁遗迹的重要性，为了解这些生态系统的自然结构和功能提供了洞察力。
We describe the abundance, biomass, size composition, and trophic structure of fish assemblages of shallow (10 m depth) fore reef habitats at 2 US Pacific atolls (Kingman, Palmyra) and 2 Kiribati-owned atolls (Tabuaeran, Kiritimati) in the northern Line Islands. Our characterization spans several coincident gradients (in human habitation and exploitation, latitude, and nutrient upwelling) from uninhabited, presently unfished, and oligotrophic Kingman to relatively densely populated, fished, and equatorially upwelled Kiritimati. Major findings are most consistent with direct effects of extraction on large-bodied predators and indirect effects on lower-level assemblage structure. Fish assemblages at Palmyra and especially Kingman atolls were characterized by high total standing biomass, large average body sizes, a preponderance of apex predators and other piscivorous fishes in an inverted biomass pyramid, few and small planktivorous fishes, and herbivores dominated by non-territorial species. Median body sizes at color change from initial to terminal phase (an index of sex change in parrotfishes) were also small for 4 species of parrotfish at Kingman and Palmyra. Fish assemblages at Tabuaeran and especially Kiritimati atolls had starkly contrasting characteristics: piscivorous and other fisheries-targeted fishes were depauperate, lower-trophic levels dominated fish biomass, planktivorous fishes were targer-bodied and more numerous, territorial herbivores were better represented, and size at maturation in parrotfishes was proportionately larger. Our results show the effects that even modest fishing effort can have on assemblage structure and indicate the importance of reefs like Kingman as increasingly rare relicts of natural coral reefs, providing insights into the natural structure and function of these ecosystems.