McInnes Julie C, Alderman Rachael, Lea Mary-Anne, Raymond Ben, Deagle Bruce E, Phillips Richard A, Stanworth Andrew, Thompson David R, Catry Paulo, Weimerskirch Henri, Suazo Cristián G, Gras Michaël, Jarman Simon N
Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tas., Australia.
Australian Antarctic Division, Kingston, Tas., Australia.
Mol Ecol. 2017 Sep;26(18):4831-4845. doi: 10.1111/mec.14245. Epub 2017 Aug 16.
Gelatinous zooplankton are a large component of the animal biomass in all marine environments, but are considered to be uncommon in the diet of most marine top predators. However, the diets of key predator groups like seabirds have conventionally been assessed from stomach content analyses, which cannot detect most gelatinous prey. As marine top predators are used to identify changes in the overall species composition of marine ecosystems, such biases in dietary assessment may impact our detection of important ecosystem regime shifts. We investigated albatross diet using DNA metabarcoding of scats to assess the prevalence of gelatinous zooplankton consumption by two albatross species, one of which is used as an indicator species for ecosystem monitoring. Black-browed and Campbell albatross scats were collected from eight breeding colonies covering the circumpolar range of these birds over two consecutive breeding seasons. Fish was the main dietary item at most sites; however, cnidarian DNA, primarily from scyphozoan jellyfish, was present in 42% of samples overall and up to 80% of samples at some sites. Jellyfish was detected during all breeding stages and consumed by adults and chicks. Trawl fishery catches of jellyfish near the Falkland Islands indicate a similar frequency of jellyfish occurrence in albatross diets in years of high and low jellyfish availability, suggesting jellyfish consumption may be selective rather than opportunistic. Warmer oceans and overfishing of finfish are predicted to favour jellyfish population increases, and we demonstrate here that dietary DNA metabarcoding enables measurements of the contribution of gelatinous zooplankton to the diet of marine predators.
胶质浮游动物是所有海洋环境中动物生物量的重要组成部分，但在大多数海洋顶级捕食者的饮食中被认为并不常见。然而，传统上主要通过对胃内容物的分析来评估海鸟等关键捕食者群体的饮食，而这种方法无法检测到大多数胶质猎物。由于海洋顶级捕食者被用于识别海洋生态系统整体物种组成的变化，饮食评估中的这种偏差可能会影响我们对重要生态系统状态转变的检测。我们利用粪便的DNA宏条形码技术研究了信天翁的饮食，以评估两种信天翁物种食用胶质浮游动物的普遍性，其中一种被用作生态系统监测的指示物种。在连续两个繁殖季节里，从覆盖这些鸟类环极分布范围的八个繁殖地收集了黑眉信天翁和坎贝尔信天翁的粪便。在大多数地点，鱼类是主要的食物项目；然而，总体上42%的样本中存在刺胞动物DNA，主要来自钵水母纲的水母，在某些地点这一比例高达80%。在所有繁殖阶段都检测到了水母，成鸟和雏鸟都会食用。福克兰群岛附近拖网渔业捕获的水母表明，在水母数量多和少的年份里，信天翁饮食中出现水母的频率相似，这表明食用水母可能是有选择性的，而不是机会性的。预计海洋变暖以及对有鳍鱼类的过度捕捞将有利于水母数量的增加，我们在此证明，饮食DNA宏条形码技术能够测量胶质浮游动物在海洋捕食者饮食中的贡献。
