Gingold Ruth, Moens Tom, Rocha-Olivares Axayácatl
Biological Oceanography Department, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, Baja California, Mexico ; Department of Biology, Ghent University, Ghent, Flanders, Belgium.
PLoS One. 2013 Jun 18;8(6):e66653. doi: 10.1371/journal.pone.0066653. Print 2013.
Biodiversity has diminished over the past decades with climate change being among the main responsible factors. One consequence of climate change is the increase in sea surface temperature, which, together with long exposure periods in intertidal areas, may exceed the tolerance level of benthic organisms. Benthic communities may suffer structural changes due to the loss of species or functional groups, putting ecological services at risk. In sandy beaches, free-living marine nematodes usually are the most abundant and diverse group of intertidal meiofauna, playing an important role in the benthic food web. While apparently many functionally similar nematode species co-exist temporally and spatially, experimental results on selected bacterivore species suggest no functional overlap, but rather an idiosyncratic contribution to ecosystem functioning. However, we hypothesize that functional redundancy is more likely to observe when taking into account the entire diversity of natural assemblages. We conducted a microcosm experiment with two natural communities to assess their stress response to elevated temperature. The two communities differed in diversity (high [HD] vs. low [LD]) and environmental origin (harsh vs. moderate conditions). We assessed their stress resistance to the experimental treatment in terms of species and diversity changes, and their function in terms of abundance, biomass, and trophic diversity. According to the Insurance Hypothesis, we hypothesized that the HD community would cope better with the stressful treatment due to species functional overlap, whereas the LD community functioning would benefit from species better adapted to harsh conditions. Our results indicate no evidence of functional redundancy in the studied nematofaunal communities. The species loss was more prominent and size specific in the HD; large predators and omnivores were lost, which may have important consequences for the benthic food web. Yet, we found evidence for alternative diversity-ecosystem functioning relationships, such as the Rivets and the Idiosyncrasy Model.
在过去几十年中，生物多样性有所减少，气候变化是主要的责任因素之一。气候变化的一个后果是海面温度升高，再加上潮间带地区的长期暴露，可能会超过底栖生物的耐受水平。由于物种或功能群的丧失，底栖生物群落可能会发生结构变化，从而使生态系统服务面临风险。在沙滩上，自由生活的海洋线虫通常是潮间带小型底栖动物中数量最多、种类最丰富的群体，在底栖食物网中发挥着重要作用。虽然显然许多功能相似的线虫物种在时间和空间上共存，但对选定的食细菌物种的实验结果表明，它们之间没有功能重叠，而是对生态系统功能有独特的贡献。然而，我们假设，当考虑到自然群落的全部多样性时，更有可能观察到功能冗余。我们用两个自然群落进行了一项微观实验，以评估它们对温度升高的应激反应。这两个群落的多样性（高[HD]与低[LD]）和环境起源（恶劣与温和条件）不同。我们从物种和多样性变化方面评估了它们对实验处理的抗逆性，并从丰度、生物量和营养多样性方面评估了它们的功能。根据保险假说，我们假设HD群落由于物种功能重叠，能够更好地应对压力处理，而LD群落的功能将受益于更适应恶劣条件的物种。我们的结果表明，在所研究的线虫群落中没有功能冗余的证据。HD群落中的物种损失更为显著且具有大小特异性；大型捕食者和杂食动物消失了，这可能对底栖食物网产生重要影响。然而，我们发现了替代的多样性-生态系统功能关系的证据，如铆钉假说和特质模型。
