ABSTRACT: Investigations of the strong environmental gradients within intertidal and subtidal rocky reefs have contributed significantly to our understanding of ecological processes, but studies exploring how algal community structure responds to the extreme environmental transition of the intertidal-subtidal interface are rare. Our objective was to examine patterns in macroalgal distribution and species richness with depth on temperate rocky reefs. Standing algal biomass and richness were measured on 6 representative reefs in southern New Zealand, across 5 depth strata from the high intertidal zone, 1.5 m above mean low water (MLW), to the subtidal zone, 10 m below MLW. We found a unimodal relationship between algal richness and biomass across the depths, where maximum species richness occurred at intermediate levels of biomass. These results are consistent with many terrestrial plant studies across strong environmental gradients. Biomass decreased down the shoreline, with the exception of the high intertidal where the lowest biomass was recorded, whilst species richness increased down the shoreline. Additionally, strong patterns of dominance were observed, with a single species (not always the same species) contributing >56% of the total biomass across all depth strata examined. This dominance could have important implications for ecosystem provisioning across this system, particularly if dominant species are found to be vulnerable to the impacts of local and/or global change. The strong environmental gradients that characterise the intertidal-subtidal transition on rocky reefs over relatively small and experimentally tractable spatial scales enable opportunities to further advance our understanding of the mechanisms controlling the distribution of biodiversity.

中文翻译：

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跨潮间带和潮下带的大型藻类群落的生物量和物种丰富度关系

摘要：对潮间带和潮间带礁石内强烈的环境梯度进行的调查，对我们对生态过程的理解做出了重要贡献，但是，研究藻类群落结构如何响应潮间带-潮间带界面的极端环境转变的研究很少。我们的目标是检查温带岩石礁上大型藻类分布和物种丰富度的规律。在新西兰南部的6个代表性礁石上测量了站立藻类生物量和丰富度，从高潮间带（平均低水（MLW）上方1.5 m）到潮下带（MLW下方10 m）跨越5个深度层。我们发现藻类丰富度与整个深度的生物量之间存在单峰关系，最大物种丰富度发生在生物量的中间水平。这些结果与在强环境梯度下进行的许多陆生植物研究一致。沿海岸线的生物量减少，但潮间带高的除外，那里记录的生物量最低，而沿岸的物种丰富度增加。此外，观察到强的优势模式，在所有深度层中，单一物种（并非总是相同物种）贡献了总生物量的> 56％。这种优势可能会对整个系统的生态系统供应产生重要影响，特别是如果发现优势物种易受本地和/或全球变化的影响。