Abstract:
Seagrass ecosystems worldwide are undergoing rapid decline due to intensifying
anthropogenic pressures and climate change, leading to severe habitat degradation and species loss. Among these, Halophila beccarii Ashcers., a small intertidal
seagrass species endemic to the Indo-Pacific, is particularly vulnerable. Despite its
ecological importance in supporting biodiversity, sediment stabilization and
carbon sequestration, the species remains understudied and its adaptive capacity
(AC) to environmental change is poorly understood. Using published literature
spanning 1977-2024, we systematically reviewed morphological, ecological, and
genetic characteristics of H. beccarii across 14 countries in the Indo-Pacific
bioregion. Following the current available AC framework, which considers species
responses to environmental change through Persist in Place (PiP) or Shift in Space
(SiS) pathways. Our synthesis revealed that H. beccarii exhibits generally low AC,
with more than half of the assessed attributes indicating limited resilience.
Although the species is reported from 13 Indo-Pacific countries, its area of
occupancy is extremely restricted (312.7 ha) and populations occur as small,
fragmented patches. Demographic observations from Malaysian population indicate an annual life cycle with rapid generational turnover and seasonal recruitment, suggesting short-term persistence potential. Additionally, limited dispersal
ability, low genetic diversity, and narrow habitat specialization constrain largescale range shifts. Overall, the adaptive profile of H. beccarii indicates a strategy
dominated by PiP responses, supported by physiological tolerance and clonal
growth, but limited capacity for spatial distribution. Country-specific conservation
policies remain scare, with only Malaysia and the Philippines incorporating the
species with national conservation and management frameworks. Without targeted conservation interventions, H. beccarii populations across the Indo-Pacific
may experience irreversible declines. Our assessments highlight the urgent need to strengthen research on key adaptive traits, particularly population genetics,
reproductive ecology and demography dynamics to refine vulnerability predictions and guide regionally coordinated conservation actions. Enhancing the AC
of H. beccarii through integrated management, restoration and monitoring
programs is critical to prevent further local extirpations and secure the resilience
of Indo-Pacific seagrass ecosystems under accelerating environmental change.