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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13349

Ecological connectivity with mangroves influences tropical seagrass population longevity and meadow traits within an island ecosystem

Amrit Kumar Mishra, Deepak Apte

*Corresponding author:

ABSTRACT: Seagrass meadows around Andaman Sea are globally significant, but declining rapidly. Assessment of the existing seagrass population dynamics is essential to facilitate effective conservation measures. We studied seagrass (Thalassia hemprichii) population dynamics at three locations in the Andaman and Nicobar Islands, surrounded by Andaman Sea. At each location, two sites were assessed, one with mangroves (MG) and another without mangroves (WMG). Quadrat and corer sampling techniques were used to collect seagrass and sediment samples. Reconstruction techniques were used to derive population dynamics of T. hemprichii. Sand fractions dominated (>90%) of the T. hemprichii meadows, with silt comprising a higher percentage only at the MG sites. The density, biomass, productivity and horizontal meadow migration of T. hemprichii were higher at the MG sites. The leaf, vertical rhizome (VR), VR internode length, the number of VR shoots-1 and vertical growth were higher at the WMG sites. T. hemprichii required least time to produce a single leaf at the MG sites than at the WMG sites. Plants associated with mangroves had four to five years of longevity with higher number of younger plants. Population growth rates were positive at all sites except at the WMG site of Burmanallah. Our results provide evidence that mangrove ecosystems have a positive impact on seagrass meadow traits and population dynamics. Therefore, it is crucial to focus on the ecological connectivity between seagrasses and associated coastal ecosystems, as it is pivotal to increase our understanding of the important link between coastal ecosystems and ecosystem functioning.