Crustose coralline algae (CCA) and other encrusting calcifiers drive carbonate production on coral reefs. However, little is known about the rates of growth and calcification of these organisms within degraded turbid reef systems. Here we deployed settlement cards (N = 764) across seven reefs in Singapore for two years to examine spatio-temporal variation in encrusting community composition and CCA carbonate production. Our results showed that CCA was the dominant encrusting taxa (63.7% ± 18.3SD) across reefs. CCA carbonate production rates (0.009–0.052 g cm⁻² yr⁻¹) were less than half of those reported for most Indo-Pacific reefs, but similar to other turbid reef systems. Highest CCA carbonate production rates were observed furthest from Singapore's main shipping port, due to a relative increase in CCA cover on the offshore reefs. Our results suggest that proximity to areas of high industrialisation and ship traffic may reduce the cover of encrusting calcifying organisms and CCA production rates which may have negative, long-term implications for the stabilisation of nearshore reefs in urbanised settings.

硬壳珊瑚藻 (CCA) 和其他结壳的钙化物推动珊瑚礁上的碳酸盐生产。然而，关于这些生物在退化的混浊礁系统中的生长和钙化速率知之甚少。在这里，我们 在新加坡的七个珊瑚礁上部署了结算卡 ( N = 764) 两年，以检查结壳群落组成和 CCA 碳酸盐生产的时空变化。我们的结果表明，CCA 是整个珊瑚礁的主要结壳类群 (63.7% ± 18.3SD)。CCA 碳酸盐生产率（0.009–0.052 g cm ^-2  yr ^-1) 不到大多数印度洋-太平洋珊瑚礁报告的一半，但与其他混浊珊瑚礁系统相似。由于近海珊瑚礁的 CCA 覆盖范围相对增加，因此在距离新加坡主要航运港口最远的地方观察到最高的 CCA 碳酸盐生产率。我们的研究结果表明，靠近高度工业化和船舶交通的地区可能会减少结壳钙化生物的覆盖和 CCA 生产率，这可能对城市化环境中近岸珊瑚礁的稳定产生负面的长期影响。