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首页> 外文期刊>Estuarine Coastal and Shelf Science >No 'silver bullet': Multiple factors control population dynamics of European purple sea urchins in Lough Hyne Marine Reserve, Ireland
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No 'silver bullet': Multiple factors control population dynamics of European purple sea urchins in Lough Hyne Marine Reserve, Ireland

机译：没有“银弹”：多个因素控制着爱尔兰洛恩海恩海洋保护区欧洲紫海胆的种群动态

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摘要

Two-decade-long monitoring studies at Europe's first statutory marine reserve-Lough Hyne in SW Ireland-indicate that benthic communities are rapidly changing. Populations of the ecologically important purple urchin (Paracentrotus lividus) have fluctuated widely, most recently with a population boom in the late 1990s, followed by a mass mortality that persists to the present day. Eight general hypotheses have been proposed to account for the urchin decline including cold temperature limiting reproduction, ephemeral algal exudates disrupting urchin fertilization, low larval availability (due to over-harvesting and/or episodic recruitment), high mortality of settlers and juveniles due to hypoxia, hyperoxia, or predation (a trophic cascade hypothesis), and increased mortality due to pathogens (stress hypothesis). The cold-temperature and the trophic cascade hypotheses appear unlikely. The remaining hypotheses, however, all seem to play a role, to some degree, in driving the urchin decline. Ulvoid exudates, for example, significantly reduced urchin fertilization and few larvae were found in plankton tows (2012-2015), indicating low larval availability in summer. Whilst settling urchins regularly recruited under shallow-subtidal rocks until 2011, no settlers were found in these habitats from 2011 to 2014 or in field experiments (2012-2018) using various settlement substrata. Seawater quality was poor in shallow areas of the lough with extreme oxygen fluctuations (diel-cycling hypoxia), and 1-day experimental exposures to DO values 1 mg L-1 were lethal to most juvenile urchins. Multiple increases of the predatory spiny starfish (Marthasterias glacialis) population in recent decades may also have contributed to the demise of the coexisting juvenile urchins. Finally, urchins of all sizes were seen suffering from dropped spines, tissue necrosis, or white-coloured infection, suggestive of stress-related pathogen mortality. There was a paucity of broken tests, indicating limited predation by large crustaceans; the large number of adult urchins 'missing' and few P. lividus tests on the north shore points to possible urchin removal by poachers and/or starfish predation. While these ecological, environmental, and anthropogenic processes occur on open coast rocky shores, many are exacerbated by the semi-enclosed nature of this fully marine sea lough due to its limited flushing. Multiple factors, including low larval availability and rapidly expanding starfish populations, coupled with degraded habitat quality (ephemeral algal mats and extreme oxygen fluctuations), indicate that the purple urchin populations will not recover without an improvement in the water quality of Lough Hyne Marine Reserve, the restocking of urchins, and protection from poaching.
机译：欧洲第一个法定海洋保护区-爱尔兰西南部的海恩·海恩（Lough Hyne）对欧洲进行了长达十年的监测研究，表明底栖生物群落正在迅速变化。具有生态重要性的紫色海胆（Paracentrotus lividus）的人口波动很大，最近一次是在1990年代后期，人口激增，随后是大规模死亡，一直持续到今天。提出了八个一般性假说来说明海胆下降的原因，包括寒冷的温度限制繁殖，短暂的藻类分泌物破坏海胆的受精，幼虫的利用率低（由于过度捕捞和/或偶发性募集），定居者和低氧导致的幼鱼的高死亡率，高氧或捕食（营养级联假说），以及病原体导致的死亡率增加（应激假说）。低温和营养级联假设似乎不太可能。但是，其余的假设似乎都在一定程度上推动了顽童的减少。例如，无卵分泌物显着减少了海胆受精，在浮游生物丝束中发现了很少的幼虫（2012-2015年），表明夏季幼虫的利用率较低。虽然在2011年之前定期在浅潮下的岩石下面招募海胆，但从2011年至2014年，在这些生境中或在使用各种沉降层的野外实验（2012-2018年）中都没有发现定居者。在浅水区中，海水的质量很差，氧气波动很大（迪尔循环缺氧），并且1天的DO值小于1 mg L-1的实验暴露对大多数幼顽童都是致命的。近几十年来，掠食性棘海星（Marthasterias glacialis）种群数量的增加也可能导致了并存的幼小海胆的灭绝。最后，发现各种尺寸的海胆都遭受脊柱掉落，组织坏死或白色感染，提示与压力有关的病原体死亡率。几乎没有破损的测试，表明大型甲壳类动物的捕食有限。成年海胆“失踪”的数量很多，而在北岸很少进行青紫李测试，这表明偷猎者和/或海星捕食可能会清除海胆。虽然这些生态，环境和人为过程发生在开阔海岸的多岩石海岸上，但由于冲刷作用有限，这种完全海洋化的海域的半封闭性质加剧了许多情况。多种因素（包括幼体可利用性低和海星种群迅速增加，以及栖息地质量下降（短暂的藻类垫和极端的氧气波动））表明，如果不改善海恩海恩海洋保护区的水质，紫色的海胆种群将无法恢复，补充海胆，防止偷猎。

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