Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, Australia.
Centre for Marine Bio-Innovation, School of Biological, Earth and Environmental Sciences, UNSW Australia, Sydney, NSW, Australia.
PLoS One. 2018 Apr 6;13(4):e0190370. doi: 10.1371/journal.pone.0190370. eCollection 2018.
Seagrasses are in decline globally due to sustained pressure from coastal development, water quality declines and the ongoing threat from climate change. The result of this decline has been a change in coastal productivity, a reduction in critical fisheries habitat and increased erosion. Attempts to slow this decline have included legislative protection of habitat and direct restoration efforts. Monitoring the success of these approaches requires tracking changes in the abundance of seagrasses, but such monitoring is frequently conducted at either too coarse a spatial scale, or too infrequently to adequately detect changes within individual meadows. Here, we used high resolution aerial imagery to quantify the change in meadows dominated by Posidonia australis over five years at 14 sites in five estuaries in south-eastern Australia. Australia has some of the world's most diverse and extensive seagrass meadows, but the widely distributed P. australis has a slow growth rate, recovers poorly after disturbance, and suffers runaway attrition if the conditions for recovery are not met. In 2010, after declines of 12-57% between the 1940s and 1980s, P. australis was listed as a threatened ecological community in New South Wales. We quantified changes in area at fine spatial scales and, where loss was observed, describe the general patterns of temporal decline within each meadow. Our results demonstrate that seagrass meadows dominated by P. australis underwent declines of ~ 2-40% total area at 11 out of 14 study sites between 2009 and 2014. In the iconic Sydney Harbour, our analyses suggest that P. australis meadows are declining at an average rate greater than 10% yr-1, exceeding the global rate of seagrass decline. Highlighting these alarming declines across the study region should serve as means to prioritise management action and review the effectiveness of legislative listing as a method to limit impacts at an ecosystem level.
由于沿海开发、水质下降和气候变化的持续压力，海草在全球范围内减少。这种减少的结果是沿海生产力的变化，关键渔业栖息地的减少和侵蚀的增加。减缓这种减少的尝试包括对栖息地的立法保护和直接恢复努力。监测这些方法的成功需要跟踪海草丰度的变化，但这种监测通常在过于粗糙的空间尺度上进行，或者过于频繁，无法在单个草地内充分检测到变化。在这里，我们使用高分辨率航空图像在澳大利亚东南部五个河口的 14 个地点，在五年内量化了由澳大利亚南部海草主导的草地的变化。澳大利亚拥有世界上最多样化和最广泛的海草草甸，但分布广泛的澳大利亚南部海草生长缓慢，在受到干扰后恢复不佳，如果恢复条件得不到满足，就会迅速减少。2010 年，在 20 世纪 40 年代至 80 年代期间下降了 12-57%之后，澳大利亚南部海草被列为新南威尔士州受威胁的生态群落。我们在精细的空间尺度上量化了面积的变化，并在观察到损失的地方，描述了每个草地内的时间衰退的一般模式。我们的结果表明，在 2009 年至 2014 年间，在 14 个研究地点中的 11 个地点，由澳大利亚南部海草主导的海草草甸的总面积减少了约 2-40%。在标志性的悉尼港，我们的分析表明，澳大利亚南部海草的衰退速度超过了全球海草衰退的平均速度，平均每年超过 10%。突出显示整个研究区域的这些令人震惊的衰退应该是优先考虑管理行动的手段，并审查立法上市作为限制生态系统层面影响的方法的有效性。
