Herrera-Escalante T, López-Pérez R A, Leyte-Morales G E
Instituto de Pesquerias, Centro Interdisciplinario de Ciencias Marinas, Av. Instituto Politecnico Nacional, Calle Palo de Santa Rita CP. 23090, La Paz, B.C.S., Mexico.
Rev Biol Trop. 2005 Dec;53 Suppl 3:263-73.
Mexican Pacific sea urchin studies have been focused mainly on species distribution, ecology and fisheries. Reef degradation by sea urchin bioerosion has not been studied previously en these reefs. We investigate the importance of Diadema mexicanum as a bioerosive agent of coral carbonate at Bahias de Huatulco, and the relative magnitude of coral accretion and bioerosion. At each of five localities in Bahias de Huatulco, sea urchin density, feeding and mechanical (spine) erosion was determined for three size class intervals. In general, D. mexicanum do not exert any significant role on coral reef community structure (live coral, dead coral or algal coverage) at the Huatulco area, probably because they are generally small (2.9-4 cm test size) and few in number (1.0-6.8 ind.m-2). Mean bioerosion rates are consistent with those measured for other diadematoids, as well as other urchin species in various eastern Pacific localities. However, the degree of bioerosive impact depends on species, test size, and population density of urchins. Coral carbonate removal by D. mexicanum erosion varies from 0.17 to 3.28 kgCaCO3m(-2)yr(-1). This represents a carbonate loss of < 5% of the annual coral carbonate production at Jicaral Chachacual, San Agustín and Isla Cacaluta, but 16 and 27% at Isla Montosa and La Entrega. On balance, coral accretion exceeds sea urchin erosion at all sites examined at Huatulco. At Bahias de Huatulco coral reef communities are actively growing, though in the coming years, it might be necessary to investigate the local effects of the interaction among erosion, and environmental and human induced perturbations.
墨西哥太平洋海胆的研究主要集中在物种分布、生态学和渔业方面。此前尚未对这些珊瑚礁上由海胆生物侵蚀导致的珊瑚礁退化进行过研究。我们调查了墨西哥冠海胆作为瓦图尔科湾珊瑚碳酸盐生物侵蚀因子的重要性，以及珊瑚生长和生物侵蚀的相对程度。在瓦图尔科湾的五个地点，对三个大小等级区间的海胆密度、摄食和机械（棘刺）侵蚀情况进行了测定。总体而言，墨西哥冠海胆在瓦图尔科地区的珊瑚礁群落结构（活珊瑚、死珊瑚或藻类覆盖度）方面并未发挥任何显著作用，这可能是因为它们通常体型较小（测试大小为2.9 - 4厘米）且数量稀少（1.0 - 6.8个/平方米）。平均生物侵蚀速率与在其他冠海胆类以及东太平洋不同地点的其他海胆物种所测得的速率一致。然而，生物侵蚀影响的程度取决于海胆的物种、测试大小和种群密度。墨西哥冠海胆侵蚀导致的珊瑚碳酸盐去除量在0.17至3.28千克碳酸钙/平方米·年之间变化。这在吉卡拉尔查查库尔、圣奥古斯丁和卡卡卢塔岛代表的碳酸盐损失量不到年珊瑚碳酸盐产量的5%，但在蒙托萨岛和拉恩特雷加岛分别为16%和27%。总体而言，在瓦图尔科所有考察地点，珊瑚生长超过海胆侵蚀。在瓦图尔科湾，珊瑚礁群落正在积极生长，不过在未来几年，可能有必要研究侵蚀与环境及人为引发的扰动之间相互作用的局部影响。
