There is little information concerning the impacts of urban development within watersheds on nutrient budgets in coastal bayous of the North Central Gulf of Mexico. The overall objective of the current study was to detect if nutrient budgets differed among bayous with varying degrees of urbanization. Three bayous (Bayou Chico, the highly urbanized bayou; Bayou Cumbest, the moderately urbanized bayou; Bayou Heron, the pristine bayou) were monitored during April, 2010-April 2011 in Mississippi. The Land-Ocean Interactions in the Coastal Zone (LOICZ) model was used to quantify the nutrient budgets. Rain and storm water discharge samples were collected and analyzed for inorganic nitrogen species and phosphate, and total suspended solids (TSS), throughout the period during precipitation events. Monthly tidal imports and exports, and standing stock water quality samples were collected and analyzed for water temperature, dissolved oxygen, salinity, specific conductance, TSS, particulate nitrogen and carbon, chlorophyll a,inorganic nitrogen species and phosphate in each bayou. Other terms for model development were derived from the literature.
Results/Conclusions
Bayou Chico exhibited the smallest area, volume, and the shallowest average depth among the three systems. Bayou Chico also exhibited the shortest exchange time of salt and water. The bayou Chico was highly net heterotrophic (-6950.52 g C/m2/yr) compared to net autotrophic processes in bayous Cumbest and Heron (24.44 and 9.08 g C/m2/yr, respectively). And Bayou Chico was largely a sink of nitrogen which moved available nitrogen away from biological pathways through dentrification (-897.53 g/m2/yr) compared to Cumbest and Heron (-2.04 g/m2/yr and -10.61 g/m2/yr, respectively).The current results showed that coastal bayous within urbanized landscapes appeared to exhibit characteristics of eutrophication processes. These results may help coastal managers to better manage coastal ecosystems health in the Northern Gulf of Mexico.