Centre for Environmental Sustainability (CEnS), School of the Environment, University of Technology Sydney, New South Wales, 2007, Australia ; Plant Functional Biology and Climate Change Cluster (C3), School of the Environment, University of Technology Sydney, New South Wales, 2007, Australia.
Centre for Environmental Sustainability (CEnS), School of the Environment, University of Technology Sydney, New South Wales, 2007, Australia ; School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University Victoria, 3216, Australia.
Ecol Evol. 2014 Feb;4(4):450-61. doi: 10.1002/ece3.933. Epub 2014 Jan 21.
Resilience is the ability of an ecosystem to recover from disturbance without loss of essential function. Seagrass ecosystems are key marine and estuarine habitats that are under threat from a variety of natural and anthropogenic disturbances. The ability of these ecosystems to recovery from disturbance will to a large extent depend on the internsity and scale of the disturbance, and the relative importance of sexual versus asexual reproduction within populations. Here, we investigated the resilience of Zostera muelleri seagrass (Syn. Zostera capricorni) to small-scale disturbances at four locations in Lake Macquarie - Australia's largest coastal lake - and monitored recovery over a 65-week period. Resilience of Z. muelleri varied significantly with disturbance intensity; Z. muelleri recovered rapidly (within 2 weeks) from low-intensity disturbance (shoot loss), and rates of recovery appeared related to initial shoot length. Recovery via rhizome encroachment (asexual regeneration) from high-intensity disturbance (loss of entire plant) varied among locations, ranging from 18-35 weeks, whereas the ability to recover was apparently lost (at least within the time frame of this study) when recovery depended on sexual regeneration, suggesting that seeds do not provide a mechanism of recovery against intense small-scale disturbances. The lack of sexual recruits into disturbed sites is surprising as our initial surveys of genotypic diversity (using nine polymorphic microsatellite loci) at these location indicate that populations are maintained by a mix of sexual and asexual reproduction (genotypic diversity [R] varied from 0.24 to 0.44), and populations consisted of a mosaic of genotypes with on average 3.6 unique multilocus genotypes per 300 mm diameter plot. We therefore conclude that Z. muelleri populations within Lake Macquarie rely on clonal growth to recover from small-scale disturbances and that ongoing sexual recruitment by seeds into established seagrass beds (as opposed to bare areas arising from disturbance) must be the mechanism responsible for maintaining the observed mixed genetic composition of Z. muelleri seagrass meadows.
弹性是生态系统在没有基本功能丧失的情况下从干扰中恢复的能力。海草生态系统是关键的海洋和河口栖息地，受到各种自然和人为干扰的威胁。这些生态系统从干扰中恢复的能力在很大程度上取决于干扰的强度和规模，以及种群内有性繁殖与无性繁殖的相对重要性。在这里，我们调查了澳大利亚最大的沿海湖泊麦夸里湖四个地点的 Zostera muelleri 海草（Syn. Zostera capricorni）对小规模干扰的恢复能力，并在 65 周的时间内监测了恢复情况。Z. muelleri 的弹性因干扰强度而异；Z. muelleri 从低强度干扰（芽损失）中迅速恢复（在 2 周内），恢复速度似乎与初始芽长有关。从高强度干扰（整个植物损失）通过根茎侵入（无性再生）的恢复在不同地点有所不同，范围从 18 到 35 周，而在依赖有性再生的情况下，恢复能力显然丧失（至少在本研究的时间范围内），这表明种子不能提供一种针对强烈小规模干扰的恢复机制。在受干扰的地点没有发现有性繁殖体令人惊讶，因为我们最初在这些地点进行的基因型多样性调查（使用 9 个多态微卫星标记）表明，种群是由有性和无性繁殖混合维持的（基因型多样性 [R] 从 0.24 到 0.44 不等），种群由基因型马赛克组成，平均每个 300 毫米直径的斑块有 3.6 个独特的多基因座基因型。因此，我们得出结论，麦夸里湖的 Z. muelleri 种群依赖于克隆生长来从小规模干扰中恢复，而种子进入已建立的海草床（而不是因干扰而出现的裸露区域）的持续有性繁殖必须是维持观察到的 Z. muelleri 海草草地混合遗传组成的机制。
