Landscape Metrics and Estuarine Sediment Contamination in the Mid‐Atlantic and Southern New England Regions

Abstract

In a previously published study, quantitative relationships were developed between landscape metrics and sediment contamination for 25 small estuarine systems within Chesapeake Bay. These analyses have been extended to include 75 small estuarine systems across the mid-Atlantic and southern New England regions of the USA. Because of the different characteristics and dynamics of the estuaries across these regions, adjustment for differing hydrology, sediment characteristics, and sediment origins were included in the analysis. Multiple linear regression with stepwise selection was used to develop statistical models for sediment metals, organics, and total polycyclic aromatic hydrocarbons (PAHs). The landscape metrics important for explaining the variation in sediment metals levels (R2 = 0.72) were the percent area of nonforested wetlands (negative contribution), percent area of urban land, and point source effluent volume and metals input (positive contributions). The metrics important for sediment organics levels (R2 = 0.5) and total PAHs (R2 = 0.46) were percent area of urban land (positive contribution) and percent area of nonforested wetlands (negative contribution). These models included silt-clay content (metals) or total organic C (organics, total PAHs) of sediments and grouping by estuarine hydrology, suggesting the importance of sediment characteristics and hydrology in mitigating the influence of the landscape metrics on sediment contamination levels. The overall results from this study are indicative of how statistical models can be developed relating landscape metrics to estuarine sediment contamination for distributions of land cover and point source discharges.

Empirical relationships between land use/cover and estuarine condition in the Northeastern United States

“…Similar relationships have been found in other EMAP research (Weisberg et al 1992;Paul et al 1999;NCCR 2001;Paul et al 2002). With all regions pooled there was a consistent relationship between estuarine condition and urban development.…”

Effects of watershed and estuarine characteristics on the abundance of submerged aquatic vegetation in Chesapeake Bay subestuaries

“…The local watershed of a subestuary can be a source of stressors, such as suspended sediment, nutrients, and colored dissolved organic matter; many studies have demonstrated that watershed characteristics affect the condition of estuarine organisms and communities (Comeleo et al 1996;Paul et al 2002;DeLuca et al 2004;King et al 2005;Bilkovic et al 2006). Land cover characteristics of watersheds can be strong indicators of degraded benthic communities (Hale et al 2004).…”

“…Watershed land cover can affect SAV by elevating nutrient and sediment loading to estuaries (Staver et al 1996), and SAV responses to watershed inputs have been considered in modeling estuarine water quality (Cerco and Cole 1993;Cerco 1995;Cerco and Moore 2001). Nonpoint source discharges of sediment and nutrients from watersheds go up with increasing proportions of either agricultural or developed lands (Frink 1991;Comeleo et al 1996;Jordan et al 1997aJordan et al ,b, 2000Jordan et al , 2003Paul et al 2002;Weller et al 2003) and croplands discharge far more nitrogen than other rural land covers (Beaulac and Reckhow 1982;Jordan et al 1997a,b). There are several possible sources of nutrients in developed land, including septic systems (Weiskel and Howes 1992;Nizeyimana et al 1996;Short and Burdick 1996), sewage system leaks, lawn fertilizers, and industrial activity (Cerco et al 2002).…”

“…In contrast to studies focused on water quality conditions near SAV beds, landscape analysis has been increasingly applied to identify watershed effects on estuarine responses (Comeleo et al 1996;Paul et al 2002;King et al 2005;Bilkovic et al 2006;Rodriguez et al 2007). Watershed land cover characteristics can be strong indicators of degraded estuarine health (Hale et al 2004;Brooks et al 2006).…”

“…Previous studies at the Smithsonian Environmental Research Center reported that local watershed land cover provided significant indicators of marsh bird diversity (DeLuca et al 2004), blue crab and bivalve abundances (King et al 2005), and toxicants in fish (King et al 2004). The most commonly used landscape indicators of estuarine condition include simple and distance-weighted land cover proportions (e.g., Paul et al 2002;Hale et al 2004;King et al 2005).…”