Morphometric variability of seagrass species in a marine-protected area of Tomia Island

Seagrass meadows are vital coastal ecosystems that deliver various ecological services, including nutrient and sediment filtration, nursery habitats for fish and shellfish, and carbon sequestration through blue carbon storage. Their remarkable phenotypic plasticity is central to their ecological success, relating to the ability to alter morphological traits in response to varying environmental conditions. This study examined the intraspecific morphometric variability of seagrasses in response to environmental gradients, including light availability, hydrology, substrate type, depth, tidal exposure, and water quality parameters, such as temperature, salinity, pH, dissolved oxygen, turbidity, and nutrient concentrations (dissolved inorganic nitrogen and phosphorus). The research was conducted in the marine-protected waters of Tomia Island, where nine seagrass species were identified: Cymodocea rotundata, Cymodocea serrulata, Enhalus acoroides, Halophila ovalis, Halodule uninervis, Halodule pinifolia, Syringodium isoetifolium, Thalassodendron ciliatum, and Thalassia hemprichii. Analysis of key morphometric traits revealed interspecific and spatial variations, including leaf length and width, number of leaves and roots, root length, and rhizome length. These findings highlight the dynamic morphological responses of seagrass communities to local environmental conditions. The results provide a baseline for localized morphometric monitoring and can inform adaptive management strategies.