Spatial Analysis of Microbiological Behavior in Sub-Tropical Coastal Wetlands

This study examines the spatial interactions between microbiological indicators and environmental factors, including water flow characteristics, in the coastal wetlands of Chabahar Bay, Iran, to assess ecological risks and guide conservation strategies. The objectives are to quantify Total Coliforms (TCs) and Fecal Coliforms (FCs) at six sampling stations and identify key environmental drivers of microbial proliferation through qualitative analysis. Field sampling was conducted over three days in October 2018 at six stations along a river feeding Chabahar’s coastal wetland. Water samples were collected during low tide. In-situ measurements of temperature, pH, humidity, and electrical conductivity were recorded. Microbiological analyses quantified total and fecal coliforms using the Most Probable Number (MPN) method. Total Organic Carbon (TOC) was measured using standard laboratory procedures, and Total Organic Matter (TOM) was determined by the loss-on-ignition method. Duplicate samples ensured data reliability, and data normality was tested with the Kolmogorov-Smirnov test. Descriptive statistics, graphical methods, and matrix analysis assessed relationships between TCs, FCs, temperature, pH, EC, TOC, and TOM. TC counts peaked at S2 (1500 MPN/100 ml), exceeding Iranian Class 2 water quality standards (1500 MPN/100 ml), with FCs detected only at S2 (900 MPN/100 ml) and S3 (23 MPN/100 ml). Temperature ranged from 30.6°C (S6) to 35.9°C (S1), showing an inverse relationship with coliform levels. EC ranged from 1900 to 24,610 μS/cm, displaying a strong inverse correlation with TCs and FCs due to salinity-induced osmotic stress. TOC and TOM peaked at S3–S4 (TOC: 2.8–3.2%; TOM: 5.1–6.0%), correlating inversely with TCs and FCs, suggesting microbial competition. pH (7.71–8.06) showed no significant correlation with coliform levels. Matrix analysis confirmed a high correlation between total and fecal coliforms (p < 0.05), with temperature and pH as independent factors. Sewage inputs at S2 drive significant microbial contamination, with coarse sediments and optimal temperatures facilitating coliform proliferation, while high EC and organic matter in mangrove zones (S3–S4) reduce coliform levels through osmotic stress and microbial competition. Mangroves at S4–S5 act as effective biofilters, mitigating contamination. These findings underscore the need for targeted sewage control and mangrove conservation to protect Chabahar Bay’s wetlands from ecological risks. Future research should examine seasonal variations and additional pollutants to improve management strategies.