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Highlights

  • Light gradients, structure zonation and diversity of aerophytic algae in caves
  • Community assembly reflects hierarchical filtering by light and moisture
  • Transition zones form ecological bottlenecks shaping microalgal diversity patterns
  • Moisture limitation can override the benefits of increased light availability
  • Artificial lighting promotes novel microalgal assemblages in tourist caves

Abstract

Cave ecosystems host specialized phototrophic biofilms structured primarily by light availability, yet quantitative assessments of aerophytic microalgal community organization in tropical limestone caves remain limited. This study investigated spatial variation in the structure of aerophytic microalgal communities across four ecologically distinct zones (entrance, transition, penetration, and low light) of Gua Tempurung, Malaysia. Stratified sampling was conducted during three seasonal periods. Dominant phototrophic morphospecies were identified using microscopy, and community composition was analyzed in relation to key environmental variables. Twenty-three dominant microalgal morphospecies were recorded across the cave gradient. Cyanobacteria constituted the major component of both richness and abundance, followed by chlorophytes and other algal groups. Community composition differed significantly among cave zones and was strongly associated with light intensity, which delineated distinct photic habitats. Species richness exhibited a unimodal response along the light gradient, with peak values observed at intermediate irradiance levels (~15.0 μmol/m² × s). Multivariate analyses indicated clear compositional turnover from illuminated entrance regions to low-light interior zones (PERMANOVA: F = 8.47, p = 0.001, R² = 0.76), reflecting strong environmental filtering driven primarily by light availability and moisture conditions. Artificial illumination associated with tourist infrastructure created locally modified microhabitats that supported additional phototrophic taxa relative to naturally dark areas, underscoring the ecological consequences of cave lighting. Together, these findings demonstrate that light availability is a primary driver of aerophytic microalgal community structure and zonation in this tropical limestone cave and provide a baseline ecological framework for future integrative studies of cave phototrophic systems.

DOI

https://doi.org/10.5038/1827-806X.ijs2594

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

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