Journal of Tropical Oceanography ›› 2025, Vol. 44 ›› Issue (4): 95-105.doi: 10.11978/2024212

• Marine Ecology • Previous Articles     Next Articles

Morphological characteristics of epilithic algal matrix and their spatial and temporal patterns in a typical fringing reef of Sanya

HU Simin1,2(), ZHOU Tiancheng1,3, ZHANG Chen1,4, JIA Nan1,4, LIU Sheng1,2(), LI Tao1,2,5, HUANG Hui1,2,5   

  1. 1. State Key Laboratory of Tropical Oceanography, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
    2. Key Laboratory of Tropical Marine Biotechnology of Hainan Province, Sanya Institute of Marine Ecology and Environmental Engineering, Sanya 572000, China
    3. Guangdong Energy Group Science and Technology Research Institute Co.Ltd., Guangzhou 510630, China
    4. University of Chinese Academy of Sciences, Beijing 100049, China
    5. Sanya Joint Laboratory of Marine Science Research, Sanya National Marine Ecosystem Research Station, Tropical Marine Biological Research Station in Hainan, Chinese Academy of Sciences, Sanya 572000, China
  • Received:2024-11-21 Revised:2024-12-08 Online:2025-07-10 Published:2025-07-31
  • Contact: LIU Sheng
  • Supported by:
    National Science & Technology Fundamental Resources Investigation Program of China(2022FY100602); National Natural Science Foundation of China(42176118); Science and Technology Planning Project of Guangdong Province, China(2023B1212060047)

Abstract:

The epilithic algal matrix (EAM) is widely distributed in coral reef ecosystems and plays a crucial role in key processes such as primary production, nutrient recycling, sediment deposition, and coral reef phase shifts. To investigate the morphological characteristics and distribution patterns of EAM, a survey was conducted in a typical Sanya fringing reef in January, April, July, and October 2022, covering three transects (1 m, 3 m, 6 m). Substrate types and their coverage were recorded via video, and three substrate types (branched, massive, planiform) with epiphytic algae were sampled by scuba diving. The results revealed significant spatial but no seasonal differences in EAM coverage in the study area. Coverage was higher at 1 m and 6 m depths (66.96%) but lower at 3 m (16.55%), showing a negative correlation with live coral coverage. EAM primarily colonized highly porous hard substrates, with the highest coverage (98%) observed on dead planiform coral reefs. However, dead massive coral reefs exhibited the highest algal height [(11.16 ± 0.68) mm], highest biomass [(118.51±33.64) g∙m-2], and greatest organic matter content [(102.49±32.94) g C∙m-2], likely due to their higher surface porosity. EAM morphological characteristics and biomass varied with depth and season, peaking at 3 m and reaching their lowest values at 1 m. Temporally, EAM height, density, and biomass were highest in summer and lowest in winter. The study indicates that the benthic community in Sanya’s Luhuitou area is dominated by long sediment-laden algal turfs (LSATs) with high sediment content and heights exceeding 5 mm. This community type is unfavorable for coral larvae sediment and is avoided by herbivorous fish. EAM morphological traits and organic matter content exhibit distinct variations across substrates, depths, and seasons. Additionally, the rich organic matter in EAM may serve as a potential food source for benthic invertebrates, playing a vital role in the coral reef ecosystem’s food web.

Key words: epilithic algal matrix, coverage, morphological characteristics, spatiotemporal differences, Sanya

CLC Number: 

  • P735