Raw Data and Parametric tests.

Caribbean reefs have experienced significant declines in live coral cover due to extreme events such as bleaching and disease outbreaks. However, the effects of chronic disturbances, such as long-term pollution, are less frequently assessed.This study examines the Barú reef in the Colombian Caribbean, which has maintained relatively good live coral cover despite being exposed to the chronic influence of the Magdalena River for approximately 70 years. Through the Dique Channel, this river reduces water quality by introducing high temperatures, low salinity, high sediment loads, reduced light penetration, excess nutrients, pathogens, and heavy metals. This makes the site ideal for evaluating multiple causes of coral mortality, assessing overall reef health, and identifying species that are either tolerant or vulnerable to chronic stressors.In 2014, researchers surveyed 2,339 coral colonies to determine the prevalence and severity of 13 signs of coral deterioration, categorized into: (1a) transmissible infectious diseases (WPD, WBD, WPX, BBD), (1b) non-transmissible, non-infectious diseases (DSD, YBD, tumors), (2) bleaching, (3) biotic interactions (overgrowth, macro-bioerosion, predation), and (4) physical damage (fragmentation and overturning). Out of the 35 scleractinian coral species recorded in the area, 31 were affected. The study found that 40% of colonies showed signs of deterioration, with a severity of 7% coral tissue loss, particularly in shallow (0–8m) and deep zones (15.1–30m).The primary cause of coral mortality was biotic interactions, particularly bioerosion, followed by overgrowth and predation. To a lesser extent, diseases (fungal infections, DSD, WBD, WPD, WPX, YBD, BBD), bleaching, and physical damage also contributed to coral decline. Species with the highest prevalence and severity of deterioration included <i>Orbicella faveolata, O. annularis, Agaricia tenuifolia, A. agaricites, A. lamarcki, Porites astreoides, Montastraea cavernosa, Pseudodiploria strigosa, O. franksi, Siderastrea siderea,</i> and <i>P. porites</i>. In contrast, more resistant species included <i>Favia fragum, Eusmilia fastigiata, Dichocoenia stokesi, Agaricia undata, Meandrina danaana, Stephanocoenia intersepta, Scolymia spp., Isophyllia spp., Madracis spp.,</i> and the zoantharian <i>Palythoa sp.</i>The findings suggest that chronic stressors, particularly freshwater discharge, are disrupting biotic interactions, leading to significant coral tissue loss and driving the ecosystem toward a phase shift, threatening reef-building species. This study highlights the importance of simultaneously monitoring multiple causes of coral mortality over different time scales, rather than focusing solely on extreme events like ENSO, bleaching, or disease outbreaks.

加勒比海珊瑚礁因珊瑚白化（bleaching）与疾病暴发等极端事件，活珊瑚覆盖度已出现显著下降。然而，诸如长期污染这类慢性扰动的影响，却较少被评估。本研究聚焦哥伦比亚加勒比海域的巴鲁礁——该礁虽已受马格达莱纳河慢性影响约70年，但其活珊瑚覆盖度仍维持在相对良好的水平。马格达莱纳河经迪克水道输入高温、低盐度、高沉积物负荷、光照穿透率下降、营养盐过剩、病原体及重金属，由此降低了该区域水质。这使得该点位成为评估珊瑚死亡多重诱因、监测珊瑚礁整体健康状况，以及甄别对慢性胁迫因子具有耐受性或易感性的物种的理想研究场地。
2014年，研究人员对2339个珊瑚群体开展调查，以明确13种珊瑚退化表征的患病率与严重程度，这些表征可分为四类：(1a) 传染性传染病（WPD、WBD、WPX、BBD）；(1b) 非传染性非感染性疾病（DSD、YBD、肿瘤）；(2) 珊瑚白化；(3) 生物相互作用（生物覆盖、大型生物侵蚀、捕食作用）；(4) 物理损伤（碎裂与倾覆）。该区域共记录到35种石珊瑚，其中31种受到影响。研究显示，40%的珊瑚群体出现退化表征，珊瑚组织损失率达7%的严重程度，这种情况在浅水区（0~8米）与深水区（15.1~30米）尤为显著。
珊瑚死亡的主要诱因为生物相互作用，尤以生物侵蚀最为突出，其次为生物覆盖与捕食作用。在较小程度上，疾病（真菌感染、DSD、WBD、WPD、WPX、YBD、BBD）、珊瑚白化及物理损伤也推动了珊瑚礁的退化。退化患病率与严重程度最高的物种包括<em>Orbicella faveolata</em>、<em>O. annularis</em>、<em>Agaricia tenuifolia</em>、<em>A. agaricites</em>、<em>A. lamarcki</em>、<em>Porites astreoides</em>、<em>Montastraea cavernosa</em>、<em>Pseudodiploria strigosa</em>、<em>O. franksi</em>、<em>Siderastrea siderea</em>以及<em>P. porites</em>。与之相对，耐受性较强的物种包括<em>Favia fragum</em>、<em>Eusmilia fastigiata</em>、<em>Dichocoenia stokesi</em>、<em>Agaricia undata</em>、<em>Meandrina danaana</em>、<em>Stephanocoenia intersepta</em>、<em>Scolymia</em> spp.、<em>Isophyllia</em> spp.、<em>Madracis</em> spp.，以及花虫类<em>Palythoa</em> sp.。
研究结果表明，慢性胁迫因子（尤以淡水径流为甚）正在破坏生物相互作用，引发显著的珊瑚组织损失，并推动生态系统发生相移，对造礁珊瑚物种构成威胁。本研究强调，相较于仅关注厄尔尼诺-南方涛动（ENSO）、珊瑚白化或疾病暴发等极端事件，同时监测不同时间尺度下珊瑚死亡的多重诱因更为重要。