Raw data for manuscript titled- Gastropod shells can act as indicators of pollutants in drainage systems for coastal cities
Description
Excel file for raw data collected during field. Site denotes place where sampling occurred, outfall status refers to control and impact site. Outfall present at impact sites and absent at control sites. Gastropod species, their number in a quadrat, number of shells which had alteration is noted down. Quadrat distance as described in methodolgy is entered. Sewage quality is a visual description. Study was undertaken to understand effect of sewage on gastropod ecology. Shell alteration was noted down and served as a bioindicator. Cause for alteration has been described and discussed in detail in the manuscript. Preliminary results show gastropods show more shell alterations in areas with an outfall. Data is open to analysis. Primary analysis was done by running GLM's for collected data. Number of gastropods, number of alterations in a quadrat served as response variables, while environmental factors served as predictor variables.
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Gradient based quadrat sampling method was used. Each sampling unit was a quadrat which was laid on three horizontal spatial scales within the vertical intertidal gradient. These imagined spatial scales were perpendicular to the direction of flow of effluent from outfall, and were denoted as: (i) High-tide Line (HTL), (ii) Low-tide Line (LTL) and (iii) Middle line (mean of distance between HTL and LTL). Quadrats were laid at distances of 20, 70 and 120 meters on either side of the outfall along the three spatial scales to account for water movements due to ocean currents and undulating topography of the intertidal zone. In a few sites where the distance of outfall from other outfalls was greater than 500 meters on either side, additional quadrats at 220 meters were added. Dat was collected during low tide less than 0.6m.