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首页> 外文期刊>Marine ecology progress series >Dimensions of diet segregation in grey seals Halichoerus grypus revealed through stable isotopes of carbon (δ ~(13)C) and nitrogen (δ ~(15)N)
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Dimensions of diet segregation in grey seals Halichoerus grypus revealed through stable isotopes of carbon (δ ~(13)C) and nitrogen (δ ~(15)N)

机译：通过碳（δ〜（13）C）和氮（δ〜（15）N）的稳定同位素揭示的灰海豹中的饮食分离尺寸

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Although many studies have documented diets for terrestrial mammals, much less is known about prey selection in marine mammals. Variation in body size of terrestrial carnivores is correlated with mass of prey consumed, and predator size often determines dietary overlap. Grey seals Halichoerus grypus are a size-dimorphic phocid seal inhabiting the Northwest Atlantic, with males 1.5 × larger than females. Stable isotopes of carbon (δ ~(13)C) and nitrogen (δ ~(15)N) provide useful tools for estimating trophic positions and carbon flow to consumers in food webs. δ ~(13)C and δ ~(15)N were analyzed for individual adult grey seals from Sable Island, Canada, between 1996 and 2001. Samples of skin were taken in May or September and the same animals were re-sampled when they returned to the breeding colony in January. In addition, samples were taken from juveniles (n = 29) in January 2004. δ ~(13)C and δ ~(15)N were also analyzed for 12 fish and 3 invertebrate species from the Scotian Shelf. Adult male (n = 36) and female (n = 36) grey seals exhibited significantly different δ ~(13)C and δ ~(15)N values (F_(1, 70) = 22.40; p ＜ 0.001). On average, males were more enriched in both δ ~(13)C and δ ~(15)N than females. While there were no differences between sex in juveniles, signatures were significantly different from adults (F_(2,101) = 28.05; p ＜ 0.001). Comparison of isotope values from potential prey suggests that adult males feed more heavily on benthic prey, whereas adult females appear to feed more on pelagic prey. Juveniles also appear to feed more on pelagic prey. These results are consistent with known differences in dive patterns and foraging behaviour in this population. In addition, there was a positive effect of body size on both δ ~(13)C (t = 2.54, p = 0.014) and δ ~(15)N (t = 2.48, p = 0.016) and a positive relationship between 815N and the rate of fat accumulation (kg d~(-1)). These results suggest an underlying energetic basis to diet variation in grey seals. Finally, examination of the variance in stable isotope ratios suggested that while individual grey seals appear to be relative specialists in their diet, niche breadth was 1.5 × greater in males than in females. On average, adult grey seals had a 2 × higher niche breadth than juveniles.
机译：尽管许多研究已经记录了陆生哺乳动物的饮食，但对海洋哺乳动物的猎物选择知之甚少。陆生食肉动物的体型变化与所消耗猎物的数量有关，而捕食者的大小通常决定了饮食的重叠。灰海豹（Shalichoerus grypus）是生活在西北大西洋的一种大小不同的变态海豹，雄性比雌性大1.5倍。碳（δ〜（13）C）和氮（δ〜（15）N）的稳定同位素为估算营养网的位置和向食物网中的消费者的碳流量提供了有用的工具。在1996年至2001年之间，对来自加拿大黑貂岛的成年灰海豹的δ〜（13）C和δ〜（15）N进行了分析。5月或9月采集了皮肤样本，对相同的动物进行了采样。一月份回到了繁殖地。此外，于2004年1月从少年（n = 29）中取样。还分析了Scotian Shelf中δ〜（13）C和δ〜（15）N的12种鱼类和3种无脊椎动物。成年男性（n = 36）和女性（n = 36）灰色海豹的δ〜（13）C和δ〜（15）N值具有显着差异（F_（1，70）= 22.40; p ＜0.001）。平均而言，雄性比雌性富集δ〜（13）C和δ〜（15）N。尽管青少年的性别没有差异，但签名与成人显着不同（F_（2,101）= 28.05； p ＜0.001）。比较潜在猎物的同位素值表明，成年雄性以底栖猎物为食，而成年雌性则以浮游性捕食为食。少年似乎还以中上层捕食为食。这些结果与该人群中潜水模式和觅食行为的已知差异相一致。另外，体型对δ〜（13）C（t = 2.54，p = 0.014）和δ〜（15）N（t = 2.48，p = 0.016）都有积极影响，而815N与正态关系和脂肪积累率（kg d〜（-1））。这些结果表明了灰海豹饮食变化的潜在能量基础。最后，检查稳定同位素比率的方差表明，虽然单个灰海豹似乎是其饮食的相对专家，但男性的生态位宽度比女性高1.5倍。平均而言，成年灰海豹的生境宽度比幼年高2倍。

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