Population structure of a newly recorded (Halodule uninervis) and native seagrass (Halophila ovalis) species from an intertidal creek ecosystem

Abstract

The presence of the seagrass Halodule uninervis was documented for the first time outside the Chilika lagoon at Haripur creek, along with previously documented Halophila ovalis from the same region. The population structure (density; biomass; leaf growth rate; and morphometrics) and environmental parameters was assessed for both seagrass species. The pH levels of the water column above both seagrass meadows were lower than the standard oceanic pH of 8.2, likely attributable to upstream freshwater influences. Halophila ovalis grew on sandy and H. uninervis on silty substrates. High nutrient (nitrate and phosphate) concentrations in the water column of the creek influenced the growth of macroalgae (Ceramium sp. and Gracilaria verrucosa) on the leaves of H. uninervis. Leaf reddening was only observed in H. ovalis leaves. Under similar environmental conditions, the shoot density and biomass (above-and below-ground) of H. ovalis were 2-fold lower that for H. uninervis. The leaves of H. uninervis were 9-fold longer than H. ovalis, whereas H. ovalis had 5-fold wider leaves than H. uninervis. The leaf plastochrone interval of H. ovalis (2.3 days) and H. uninervis (9.6 days) was similar for the Indian Ocean region. Consequently, the H. ovalis leaf growth rate was 2-fold lower than that for H. uninervis. H. ovalis shoot internodes were 2.6-fold longer than for H. uninervis, whereas the root lengths of H. uninervis were longer than for H. ovalis.The shorter root length of H. ovalis resulted in a higher branching frequency than for H. uninervis. The total C and N content were higher in the H. ovalis leaves than those of H. uninervis. This study suggest seagrass responses to similar environmental conditions are species-specific. Regular assessment of the seagrass population structure and water quality monitoring of Haripur creek are essential for better management and conservation of these important seascapes.

Seagrass ecosystem adjacent to mangroves store higher amount of organic carbon of Andaman and Nicobar Islands, Andaman Sea

“…However, through this carbon storage study of ecologically connected seagrass and mangrove ecosystems of ANI, this study emphasizes on the importance of seagrass ecosystems. Secondly, as these seagrass ecosystems are adjacent to mangrove ecosystems of ANI, these ecosystems can be considered along the Mangroves for the Future (MFF) and Island Protection Zones (IPZ) programs of the NAPCC for initiating conservation and management practices for seagrass ecosystems of India that are under decline from various anthropogenic activities (Mishra and Apte, 2020;Mishra et al, 2021aMishra et al, , 2021b. Loss of seagrass ecosystems of India will make these ecosystems as source of carbon emission than storehouse and can release various other greenhouse gases .…”