Spatial dynamics of macrophytes and associated macrofauna in Pambala – Chillaw Lagoon, Sri Lanka
Ocean University Of Sri LankaAuthors
Liyange P.D.I.S*, Kumara M.P
Introduction: What conservation problem or question does your study address?
Photosynthetic plants grow in different communities completely or periodically submerged in water are termed as aquatic macrophytes. These plants make complex, multifaceted habitats for macrofauna. International studies highlighted the importance and influence on anthropogenic activities but in national level, Sri Lanka’s attention is less. The study was aimed to find the spatial variations of the functional aspects of these habitats in a selected coastal area
Methods: What were the main research methods you used?
Four different macrophyte sites: a brush pile fishery, open water, a boat slipway and a site shaded with mangroves was selected. Six randomly selected 25 cm x 25 cm quadrates were studied at each site. Water pH, salinity of each quadrate was measured and was cut down to a 15 cm depth, washed over a 1mm mesh to divide into flora and fauna components. Component of each site was identified to their lowest taxonomic level. Samples were further separated to their above and belowground components and separately dried to a constant weight. Mean values of above ground and below ground biomass (gm-2) and % cover m-2 were calculated averaging the flora values. Friedman tests were used to compare the mean values. Then, mean values of abundance (m-2), abiotic data similarity and relationships and differences of abundance between sites were calculated using different statistical methods and software.
Results: What are your most important results?
Water was more brackish when sampling. Flore were Najas marina and two Najas sp with significant differences in mean % cover. No differences in above and belowground dry biomass. 12 macrofauna types of 8 families noted with significant abundance association. Boat slipway and mangrove site groped at 60% similarity of abundance with significant differences. Highest fauna density marked in a Brachiodontes sp. and family Potamididae had highest species diversity index
Discussion: What are your important discussion points and what is the relevance of your results to conservation (if any)?
Sites indicated freshwater conditions for the studied period. Non-mechanized boats in boat slipway may resulted low above and belowground dry weight and % macrophyte cover. The lagoon provides habitats for 12 different macrofauna types pointing the ecological role of macrophytes. The open water site would indicate the higher role of habitat provision and implies this environment is the most suitable habitat for higher abundance of macrofauna.