Biology subjects

Apte, D.

Publications and source records attributed to Apte, D..

3 recordsLinked to original sources

bioRxiv2020

Reproductive effort of intertidal tropical seagrass as an indicator of habitat disturbance

Habitat disturbance is one of the major causes of seagrass loss around the Andaman Sea in the Indian Ocean bioregion. Assessing the seagrass response to these disturbances is of utmost importance in planning effective conservation measures. Here we report about seagrass reproductive effort (RE) as an indicator to assess seagrass response to habitat disturbances. Quadrat sampling was used to collect seagrass samples at three locations (a disturbed and undisturbed site per location) of the Andaman and Nicobar Islands. The health of seagrass meadows was quantified based on density-biomass indices of the disturbed sites. A change ratio (D/U) was derived by contrasting the RE of disturbed (D) sites with the undisturbed (U) sites of all three locations. The relationship between RE and plant morphometrics were also quantified. Reproductive density of T. hemprichii was higher and significant at the three disturbed sites. The average reproductive density of T. hemprichii at the disturbed sites was 3.3-fold higher than the undisturbed sites. The reproductive density consisted around 52% of the total shoot density of T. hemprichii at the disturbed sites. In general, the increase in the plant RE was site-specific and was 4-fold higher at the three disturbed sites. Positive and significant correlations was observed between the change ratio of RE and the plant morphometrics, suggesting an active participation of seagrass morphometrics in the reproductive process. Increase in seagrass RE can contribute to the increase in population genetic diversity, meadow maintenance and various ecosystem functions under the influence of anthropogenic disturbance scenarios.

ecology↗

bioRxiv2019

Ecological association between seagrass and mangrove ecosystems increases seagrass population longevity in island ecosystem

We report for first time about tropical seagrass meadows association with mangrove ecosystems and its effect on seagrass population dynamics off India in Andaman Sea. Two sites of Neil island, i.e. site 1, associated with mangroves and site 2 without mangroves were selected. Quadrat sampling (n=5) were used to collect sediment and seagrass samples. Reconstruction techniques were used to derive population age structure. T. hemprichii population was found mostly with sandy substrate at both sites, with silt consisting very low fraction at site 1. Density, biomass, productivity and morphometric features of T. hemprichii were significantly higher at site1. Reproductive density was higher at site 1, whereas reproductive effort to produce fruits were higher at site 2. The rhizome (vertical+ horizontal) production rates were higher at site 1 and the vertical elongation rate was higher at site 2. Plastochrome interval for site1 and 2 were 25.49 and 26.80 days respectively leading to formation of 14.31 and 13.62 leaves per year. T. hemprichii population at site 1 had four years of longevity and higher younger plants compared to site 2. The long-term average recruitment and present recruitment rate were higher at site 1 compared to site 2, resulting in steady state growth of the overall population at site 1. Higher number of younger plants suggests fitness of the T. hemprichii population at site 1, which increases the ecological significance of mangrove ecosystems have on seagrass population dynamics. This association should be considered for better management and conservation practices of coastal seascapes under global change scenarios.

ecology↗

bioRxiv2019

Boat anchors not OK: Loss of Dugong grass (Halophila ovalis) population structure in Havelock island of Andaman and Nicobar Islands, India

Anthropogenic disturbance due to deployment of boat anchors and loss of seagrass ecosystem is not well understood in India. So, we used Govind Nagar beach of Havelock Island of Andaman and Nicobar Islands (ANI)to assess the impacts of boat anchors from traditional fishing and recreational activities on the seagrass Halophila ovalis population structure. H. ovalis density, biomass, morphometrics, canopy height and percentage cover were estimated from two stations of Govind Nagar beach i.e., one highly impacted from boat anchors (Station1) and a sheltered station (Station 2). A clear evidence in reduction of shoot density of H. ovalis was observed at station 1, exception was similar apex densities between both stations. H. ovalis morphometrics, such as number of leaves per shoot, leaf length, width and horizontal rhizome length were observed with significant lower values at station 1 compared to the sheltered station 2. Reduction in seagrass morphometrics also resulted in the loss of seagrass canopy height and percentage cover. A clear evidence of loss of seagrass population structure under the influence of physical disturbances caused by boat anchors were observed. We report for the first time the impacts of boat anchors on seagrass ecosystems of India and our results pitch for wider studies across India. The impact of boat anchors is small-scale, but in long-term loss of seagrass ecosystem services will have dire consequences on fish habitat and carbon storage. Therefore, proper management and conservation measures should be taken to prevent the loss of important dugong grass habitats of ANI.\n\nHighlightsO_LIPhysical disturbances caused by boat anchors decreased the shoot density of H. ovalis by 1.2-fold.\nC_LIO_LI1 to 2-fold reduction in canopy height and the morphological features of individual plants were observed due to damage caused by boat anchors\nC_LIO_LIHabitat disturbance reduced 1.6-fold percentage cover of H. ovalis at Havelock Island of Andaman and Nicobar Islands, India\nC_LI

ecology↗