The response of Chesapeake Bay salinity to climate‐induced changes in streamflow

Abstract

Autoregressive statistical models of monthly salinity variations in the mainstem of Chesapeake Bay are developed for use in climate change applications. Observations of salinity and Susquehanna River flow from 1984 to 1994 are used to calibrate the models. Up to 93% of the variance in salinity is captured by these models, with the best fits occurring in the middle of the bay, where submonthly fluctuations due to river flow and oceanic currents are damped. Our salinity models use output from a climate-forced hydrological model under a doubling of present-day atmospheric CO 2 . This coupling scheme predicts salinity changes between ϩ3.5% and Ϫ27.5% near the mouth of the Susquehanna River, to between ϩ0.1% and Ϫ0.7% near the ocean. These ranges demonstrate the uncertainty in climate model predictions, although three of the four scenarios used indicate increased Susquehanna River flow and therefore decreased salinity. In the highest flow scenario (a 32% annual increase) our results show that the bay's isohalines may recede by approximately 6.3 km (about 2% of the length of the bay) near the Susquehanna River, to as much as 55 km (about 17% of the length of the bay) near the middle bay. This shift implies that climate change may have consequences for organisms with low-salinity thresholds, including oysters and crabs.

Influence of Environmental Factors onVibriospp. in Coastal Ecosystems

“…In most studies that included temperature, it was at least as important as the other factors studied, and it has often been the only statistically significant factor that was associated with vibrios. Given that Vibrio densities are so closely linked to temperatures in aquatic systems that have climate change implications (1,105,106,107,108,109,110), and given that increased global populations will likely lead to further cholera infections, in addition to increased frequency and speed of global mobility, more studies are needed that address the potentially pathogenic subpopulations of Vibrio spp., particularly V. cholerae, as well as including those that have not yet caused high rates of human illness. A major challenge is the fact that potentially pathogenic vibrios, that is, those carrying virulence factors, such as cholera toxin and tdh, are often below the detection limit of most studies, even when filtration methods are used.…”

Predictability of Vibrio cholerae in Chesapeake Bay

“…Whatever the mechanisms, these results suggest that year-to-year salinity variability or other factors associated with freshwater influx may generate large variations in the V. cholerae populations. For example, lower salinities in the upper bay due to increased Susquehanna River flow, a possible outcome of climate change scenarios that include a doubling of atmospheric carbon dioxide (27), may favor increased occurrence of V. cholerae in Chesapeake Bay. Conversely, drought conditions, such as those experienced in recent years in the Chesapeake Bay region, may produce conditions less conducive to V. cholerae proliferation in the estuary.…”

The Medieval Climate Anomaly and Little Ice Age in Chesapeake Bay and the North Atlantic Ocean

“…Density-driven CB circulation is influenced by freshwater river discharge and inflowing marine water. Susquehanna River water, which accounts for up to 62% of the total freshwater input, enters the bay in the north and exerts a dominant control over circulation (Gibson and Najjar, 2000). Ocean water enters the bay from the Mid-Atlantic Bight (MAB) on the adjacent continental shelf such that mixing of freshwater from the north and ocean water from the south results in a stratified water column that overshadows short-term effects of tides, wind, storms and topography over interannual and decadal timescales (Boicourt et al, 1999).…”