No abstract

Seagrass phenophases are crucial in understanding their reproductive biology but are seldom documented. We studied flowering and fruiting phenophases of Enhalus acoroides from a mixed-species intertidal seagrass meadow in Ritchie’s archipelago, Andaman Islands, India. The estimated mean densities of pistillate and staminate flowers were 16.0 ± 12.0/ m2 and 12.7 ± 7.3/ m2, respectively. We observed the bloom of free-floating male flowers (961.7 ± 360.4/ m2) during the spring low tides (at mean sea surface temperature ~30°C). Seagrass cover, shoot density, and canopy height of E. acoroides, along with flowering densities, showed a zonal variation within the sampled meadow. We report the first-time observations of several phenophases of E. acoroides, such as female inflorescence buds, male inflorescence, a bloom of released male flowers, pollination, and fertilized flowers from the Indian waters. We also report the prevailing threats to seagrass meadows, such as meadow scarring done by boat anchorage in the Andaman Islands.

Dugongs, exclusively seagrass foragers, are globally threatened marine mammals. Knowledge on their feeding biology has been derived from few direct observations and mostly by analysis of stomach contents. Given limitations in data from Indian populations, dugong strandings serve as an opportunity to understand their dietary composition through gut sampling. In this paper, we utilize the gut contents collected from stranded dugongs to detect differences in the seagrass foraging between two isolated pockets of dugong distribution (Tamil Nadu and Gujarat) and supplement existing knowledge on dugong feeding biology in Indian waters. We extracted, enumerated and identified seagrass species from dugong gut contents. The proportion of seagrass leaf fragments were found higher (>40%) than other fragments in all the gut samples analysed. We recorded two seagrass genera (Halophila spp. and Halodule spp.) from Gujarat and five seagrass genera (Halophila spp., Halodule spp., Cymodocea spp., Enhalus spp., Syringodium spp.) from Tamil Nadu dugong individuals. We also obtained anthropogenic debris such as plastic, fishing net and wood fragments from the gut samples. We suggest enhanced monitoring of seagrass habitats and fine spatial scale threat mapping in entire dugong distribution range in India.