Table1.DOCX

Pollution, fishing, and outbreaks of predators can heavily impact coastal coral reef ecosystems, leading to decreased water quality and benthic community shifts. To determine the main environmental drivers of coral reef status in the Spermonde Archipelago, Indonesia, we monitored environmental variables and coral reef benthic community structure along an on-to-offshore gradient annually from 2012 to 2014. Findings revealed that concentrations of phosphate, chlorophyll a-like fluorescence, suspended particulate matter, and light attenuation significantly decreased from on-to-offshore, while concentrations of dissolved O2 and values of water pH significantly increased on-to-offshore. Nitrogen stable isotope signatures of sediment and an exemplary common brown alga were significantly enriched nearshore, identifying wastewater input from the city of Makassar as primary N source. In contrast to the high temporal variability in water quality, coral reef benthic community cover did not show strong temporal, but rather, spatial patterns. Turf algae was the dominant group next to live coral, and was negatively correlated to live coral, crustose coralline algae (CCA), rubble and hard substrate. Variation in benthic cover along the gradient was explained by water quality variables linked to trophic status and physico-chemical variables. As an integrated measure of reef status and structural complexity, the benthic index, based on the ratio of relative cover of live coral and CCA to other coral reef organisms, and reef rugosity were determined. The benthic index was consistently low nearshore and increased offshore, with high variability in the midshelf sites across years. Reef rugosity was also lowest nearshore and increased further offshore. Both indices dropped in 2013, increasing again in 2014, indicating a period of acute disturbance and recovery within the study and suggesting that the mid-shelf reefs are more resilient to disturbance than nearshore reefs. We thus recommend using these two indices with a selected number of environmental variables as an integral part of future reef monitoring.

污染、捕捞以及捕食者种群爆发可对沿岸珊瑚礁生态系统造成严重冲击，进而导致水质下降与底栖生物群落（benthic community）结构演替。为探明印度尼西亚斯佩蒙德群岛珊瑚礁健康状况的主要环境驱动因子，我们于2012-2014年间沿近岸-离岸梯度逐年监测环境变量与珊瑚礁底栖生物群落结构。研究结果显示，磷酸盐、类叶绿素a荧光、悬浮颗粒物以及光衰减系数沿近岸-离岸梯度显著降低，而溶解氧（dissolved O₂）与水体pH值则沿该梯度显著升高。沉积物与典型常见褐藻的氮稳定同位素（nitrogen stable isotope）特征在近岸区域显著富集，表明望加锡市的废水输入是主要的氮来源。与水质的高时间变异性不同，珊瑚礁底栖生物群落覆盖率并未呈现显著的时间变化规律，而是呈现出空间分布模式。藻席藻类是仅次于活珊瑚的优势类群，且与活珊瑚、结壳珊瑚藻（crustose coralline algae, CCA）、碎石与硬质基底呈显著负相关。沿该梯度的底栖生物覆盖率变化可由与营养状态相关的水质变量以及理化变量加以解释。以活珊瑚与结壳珊瑚藻相对覆盖率相较于其他珊瑚礁生物的比值为基础构建的底栖指数（benthic index），以及礁体粗糙度（reef rugosity），被作为珊瑚礁健康状况与结构复杂度的综合衡量指标进行测定。底栖指数在近岸区域持续偏低，并沿离岸方向逐渐升高，陆架中部区域的底栖指数在各年间存在较高变异性。礁体粗糙度同样在近岸区域最低，并随离岸距离增加而升高。两项指标均在2013年出现下降，并于2014年再次回升，表明研究期间存在一段剧烈扰动与恢复的阶段，同时也说明陆架中部珊瑚礁相较于近岸珊瑚礁对扰动具有更强的恢复力。因此，我们建议将这两项指标与选定的若干环境变量结合使用，作为未来珊瑚礁监测的核心组成部分。