Dyson Kirstie E, Bulling Mark T, Solan Martin, Hernandez-Milian Gema, Raffaelli David G, White Piran C L, Paterson David M
Gatty Marine Laboratory, University of St Andrews, Fife KY16 8LB, UK.
Proc Biol Sci. 2007 Oct 22;274(1625):2547-54. doi: 10.1098/rspb.2007.0922.
Despite the complexity of natural systems, heterogeneity caused by the fragmentation of habitats has seldom been considered when investigating ecosystem processes. Empirical approaches that have included the influence of heterogeneity tend to be biased towards terrestrial habitats; yet marine systems offer opportunities by virtue of their relative ease of manipulation, rapid response times and the well-understood effects of macrofauna on sediment processes. Here, the influence of heterogeneity on microphytobenthic production in synthetic estuarine assemblages is examined. Heterogeneity was created by enriching patches of sediment with detrital algae (Enteromorpha intestinalis) to provide a source of allochthonous organic matter. A gradient of species density for four numerically dominant intertidal macrofauna (Hediste diversicolor, Hydrobia ulvae, Corophium volutator, Macoma balthica) was constructed, and microphytobenthic biomass at the sediment surface was measured. Statistical analysis using generalized least squares regression indicated that heterogeneity within our system was a significant driving factor that interacted with macrofaunal density and species identity. Microphytobenthic biomass was highest in enriched patches, suggesting that nutrients were obtained locally from the sediment-water interface and not from the water column. Our findings demonstrate that organic enrichment can cause the development of heterogeneity which influences infaunal bioturbation and consequent nutrient generation, a driver of microphytobenthic production.
尽管自然系统复杂，但在研究生态系统过程时，很少考虑栖息地破碎化所导致的异质性。那些考虑了异质性影响的实证方法往往偏向于陆地栖息地；然而，海洋系统因其相对易于操控、响应时间快以及大型底栖动物对沉积物过程的影响已为人熟知等优势，提供了研究机会。在此，研究了异质性对人工河口组合中微型底栖植物生产的影响。通过用碎屑藻类（肠浒苔）富集沉积物斑块来制造异质性，以提供一种外源有机物质来源。构建了四种数量上占优势的潮间带大型底栖动物（多变钩虾、绿玉黍螺、内卷齿蚕、波罗的海麦蛤）的物种密度梯度，并测量了沉积物表面的微型底栖植物生物量。使用广义最小二乘回归的统计分析表明，我们系统内的异质性是一个重要驱动因素，它与大型底栖动物密度和物种身份相互作用。微型底栖植物生物量在富集斑块中最高，这表明养分是从沉积物 - 水界面局部获取的，而非来自水柱。我们的研究结果表明，有机富集可导致异质性的发展，而异质性会影响底内动物的生物扰动以及随之产生的养分生成，这是微型底栖植物生产的一个驱动因素。
