Potential Effects of Climate Change on Freshwater Ecosystems of the New England/Mid-Atlantic Region

Abstract

Numerous freshwater ecosystems, dense concentrations of humans along the eastern seaboard, extensive forests and a history of intensive land use distinguish the New England/Mid‐Atlantic Region. Human population densities are forecast to increase in portions of the region at the same time that climate is expected to be changing. Consequently, the effects of humans and climatic change are likely to affect freshwater ecosystems within the region interactively. The general climate, at present, is humid continental, and the region receives abundant precipitation. Climatic projections for a 2 × CO2 atmosphere, however, suggest warmer and drier conditions for much of this region. Annual temperature increases ranging from 3–5°C are projected, with the greatest increases occurring in autumn or winter. According to a water balance model, the projected increase in temperature will result in greater rates of evaporation and evapotranspiration. This could cause a 21 and 31% reduction in annual stream flow in the southern and northern sections of the region, respectively, with greatest reductions occurring in autumn and winter. The amount and duration of snow cover is also projected to decrease across the region, and summer convective thunderstorms are likely to decrease in frequency but increase in intensity. The dual effects of climate change and direct anthropogenic stress will most likely alter hydrological and biogeochemical processes, and, hence, the floral and faunal communities of the region's freshwater ecosystems. For example, the projected increase in evapotranspiration and evaporation could eliminate most bog ecosystems, and increases in water temperature may increase bioaccumulation, and possibly biomagnification, of organic and inorganic contaminants. Not all change may be adverse. For example, a decrease in runoff may reduce the intensity of ongoing estuarine eutrophication, and acidification of aquatic habitats during the spring snowmelt period may be ameliorated. Recommendations for future monitoring efforts include: (1) extending and improving data on the distribution, abundance and effect of anthropogenic stressors (non‐point pollution) within the region; and (2) improving scientific knowledge regarding the contemporary distribution and abundance of aquatic species. Research recommendations include: (1) establishing a research centre(s) where field studies designed to understand interactions between freshwater ecosystems and climate change can be conducted; (2) projecting the future distribution, activities and direct effects of humans within the region; (3) developing mathematical analyses, experimental designs and aquatic indicators that distinguish between climatic and anthropogenic effects on aquatic systems; (4) developing and refining projections of climate variability such that the magnitude, frequency and seasonal timing of extreme events can be forecast; and (5) describing quantitatively the flux of materials (sediments, nutrients, metals) from watersheds characterized by a mosaic of land u...

Temperature controls a latitudinal gradient in the proportion of watershed nitrogen exported to coastal ecosystems

“…With a doubling of atmospheric CO 2 , global average temperature is expected to increase anywhere between 1.5 and 4.5°C (Houghton et al 2001) and by up to 5°C in winter in the northern section of the U.S. (Moore et al 1997). The relationships presented here predict increased N processing efficiency in warmer watersheds and a northward shift of the breakpoint, resulting in a lower proportionate N export to the coastal zone in the northern and mid-Atlantic states.…”

Climate simulations of major estuarine watersheds in the Mid-Atlantic region of the US

“…As several past studies of Mid-Atlantic climate change have been conducted for a CO 2 doubling (McCabe and Ayers 1989; Moore et al 1997;Najjar 1999) we selected transient results from the literature and from our study that corresponded most closely to these conditions: 2090-2099 for the 1% per year simulations of Polsky et al (2000) and 2070-2099 for the A2 simulations presented by Hayhoe et al (2007) and us. Figure 10 summarizes the results.…”

“…Several studies utilized projections of GCMs forced by a doubling of atmospheric CO 2 over different domains: the Delaware River Basin (McCabe and Ayers 1989), the New England/Mid-Atlantic region (Moore et al 1997), and the Susquehanna River Basin (Najjar 1999). Two transient studies have been conducted: two GCMs forced by CO 2 increases of 1% per year were analyzed in the Mid-Atlantic ; and nine GCMs forced by up to three CO 2 emissions scenarios were analyzed for the US Northeast (Hayhoe et al 2007).…”

Trends in estuarine fish assemblages facing different environmental conditions: combining diversity with functional attributes

“…In addition, most fish species are good indicators of long-term effects and largescale habitat conditions (Moore et al 1997). In this sense, several fish species are known to respond to changes in hydrologic regimes which, among other factors, are related with water quality (Attrill and Power 2000) and with the extension of river plumes to adjacent coastal areas (Vinagre et al 2008;Martinho et al 2008).…”