Rovellini Alberto, Mortimer Charlotte L, Dunn Matthew R, Fulton Elizabeth A, Jompa Jamaluddin, Haris Abdul, Bell James J
School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand.
National Institute of Water and Atmospheric Research (NIWA), Wellington, New Zealand.
Mar Environ Res. 2024 Jan;193:106254. doi: 10.1016/j.marenvres.2023.106254. Epub 2023 Nov 8.
Corals provide a complex 3D framework that offers habitat to diverse coral reef fauna. However, future reefs are likely to experience reduced coral abundance. Sponges have been proposed as one potential winner on future coral reefs, but little is known of how they contribute to reef 3D structure. Given the ecological importance of structural complexity, it is critical to understand how changes in the abundance of structure-building organisms will affect the three-dimensional properties of coral reefs. To investigate the potentially important functional role of coral reef sponges as providers of structural complexity, we compared the structural complexity of coral- and sponge-dominated areas of an Indonesian coral reef, using 3D photogrammetry at a 4 m spatial scale. Structural complexity of 31 4 m quadrats was expressed as rugosity indicating reef contour complexity (R), vector dispersion indicating heterogeneity of angles between reef surfaces (1/k), and fractal dimension indicating geometrical complexity at five different spatial scales between 1 and 120 cm (D). Quadrats were identified as high- or low-complexity using hierarchical clustering based on the complexity metrics. At high structural complexity, coral- and sponge-dominated quadrats were similar in terms of R and 1/k. However, smallest-scale refuge spaces (1-5 cm) were more abundant in coral-dominated quadrats, whereas larger scale refuge spaces (30-60 cm) were more abundant in sponge-dominated quadrats. Branching and massive corals contributed the most to structural complexity in coral-dominated quadrats, and barrel sponges in sponge-dominated quadrats. We show that smaller-scale refugia (1-5 cm) are reduced on sponge-dominated reefs at the spatial scale considered here (4 m), with potential negative implications for smaller reef fauna.
珊瑚提供了一个复杂的三维框架，为各种珊瑚礁动物群提供了栖息地。然而，未来的珊瑚礁可能会经历珊瑚丰度的下降。海绵被认为是未来珊瑚礁上的一个潜在赢家，但人们对它们如何影响珊瑚礁的三维结构知之甚少。鉴于结构复杂性的生态重要性，了解造礁生物丰度的变化将如何影响珊瑚礁的三维特性至关重要。为了研究珊瑚礁海绵作为结构复杂性提供者的潜在重要功能作用，我们使用4米空间尺度的三维摄影测量法，比较了印度尼西亚一个珊瑚礁中以珊瑚为主和以海绵为主区域的结构复杂性。31个4米见方区域的结构复杂性用表示礁轮廓复杂性的粗糙度（R）、表示礁表面之间角度异质性的矢量离散度（1/k）以及表示1至120厘米之间五个不同空间尺度几何复杂性的分形维数（D）来表示。根据复杂性指标，通过层次聚类将样方确定为高复杂性或低复杂性。在高结构复杂性下，以珊瑚为主和以海绵为主的样方在R和1/k方面相似。然而，在以珊瑚为主的样方中，最小尺度的避难空间（1 - 5厘米）更为丰富，而在以海绵为主的样方中，较大尺度的避难空间（30 - 60厘米）更为丰富。在以珊瑚为主的样方中，分支状和块状珊瑚对结构复杂性贡献最大，在以海绵为主的样方中，桶状海绵贡献最大。我们发现，在此处考虑的空间尺度（4米）上，以海绵为主的珊瑚礁上较小尺度的避难所（1 - 5厘米）减少，这可能对较小的珊瑚礁动物群产生负面影响。
