Depth segregation and diet disparity revealed by stable isotope analyses in sympatric herbivorous cichlids in Lake Tanganyika.
Depth segregation and diet disparity revealed by stable isotope analyses in sympatric herbivorous cichlids in Lake Tanganyika.
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DOI：
10.1186/s40851-015-0016-1
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发表时间：
2015
影响因子：
2.7
通讯作者：
Hori M
中科院分区：
文献类型：
--
作者：
Hata H;Shibata J;Omori K;Kohda M;Hori M
非洲大裂谷的坦噶尼喀湖被认为是慈鲷适应辐射的场所。各种草食性鱼类共存于湖的岩石沿岸的。食草性慈鲷获得了多种喂养的生态形态，包括食草动物，浏览器，刮刀，铲，并隔离饮食生态位。然而，在每个生态形态中，多个物种显然在岩石斜坡上共域共存。先前对它们行为的观察表明，这些慈鲷类栖息在仅相隔数米的离散深度。本文以碳、氮稳定同位素比值为指标，研究了慈鲷科鱼类在不同深度摄食区对附着生物的营养吸收。鱼类肌肉的δ 15 N在慈鲷生态型之间存在差异;这在食草动物中显著低于浏览者和铲形动物，尽管在领土内的附着生物中δ 15 N水平在领土物种之间没有差异。这表明食草动物更直接地依赖于附着生物的初级生产，而其他动物则从更高的营养级摄取动物物质。在δ 13 C方面，只有食浮游生物的鱼类表现出较低的值，表明这些鱼类依赖于浮游植物的生产，而其他鱼类则依赖于附着生物的生产。无论慈鲷生态型如何，附着生物的δ 13 C与生境深度显著相关，随生境深度的增加而降低。区域性鱼类肌肉中δ 13 C与区域内附着生物的δ 13 C显著相关，表明这些食草性慈鲷依赖于区域内附着生物的初级生产。碳和氮的稳定同位素比值不同的ecomorphs和慈鲷物种在同一ecomorphs同域居住的沿岸的地区的坦噶尼喀湖，这表明这些慈鲷是隔离营养源，由于不同的依赖在不同的ecomorphs（特别是在食草动物和浏览器），并由于隔离的物种相同的ecomorphs喂养深度，食草动物和浏览器，特别是。本文的在线版本（doi：10.1186/s40851-015-0016-1）包含补充材料，可供授权用户使用。
Lake Tanganyika in the African Great Rift Valley is known as a site of adaptive radiation in cichlid fishes. Diverse herbivorous fishes coexist on a rocky littoral of the lake. Herbivorous cichlids have acquired multiple feeding ecomorphs, including grazer, browser, scraper, and scooper, and are segregated by dietary niche. Within each ecomorph, however, multiple species apparently coexist sympatrically on a rocky slope. Previous observations of their behavior show that these cichlid species inhabit discrete depths separated by only a few meters. In this paper, using carbon (C) and nitrogen (N) stable isotope ratios as markers, we followed the nutritional uptake of cichlid fishes from periphyton in their feeding territories at various depths. δ15N of fish muscles varied among cichlid ecomorphs; this was significantly lower in grazers than in browsers and scoopers, although δ15N levels in periphyton within territories did not differ among territorial species. This suggests that grazers depend more directly on primary production of periphyton, while others ingest animal matter from higher trophic levels. With respect to δ13C, only plankton eaters exhibited lower values, suggesting that these fishes depend on production of phytoplankton, while the others depend on production of periphyton. Irrespective of cichlid ecomorph, δ13C of periphyton correlated significantly with habitat depth, and decreased as habitat depth became deeper. δ13C in territorial fish muscles was significantly related to that of periphyton within their territories, regardless of cichlid ecomorph, which suggests that these herbivorous cichlids depend on primary production of periphyton within their territories. Carbon and nitrogen stable isotope ratios varied among ecomorphs and among cichlid species in the same ecomorphs sympatrically inhabiting a littoral area of Lake Tanganyika, suggesting that these cichlids are segregated by nutrient source due to varying dependency on periphyton in different ecomorphs (especially between grazers and browsers), and due to segregation of species of the same ecomorph by feeding depth, grazers and browsers in particular. The online version of this article (doi:10.1186/s40851-015-0016-1) contains supplementary material, which is available to authorized users.