Chesapeake Bay Acidification
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the extent of acidification through time, and that inform the design of biological experiments and
observation networks.
In addition to fluxes in carbon, inputs of total alkalinity to estuaries and coastal waters from rivers, tidal
saltmarshes, and other fringing habitats at the land:water interface can have important impacts on the
buffering capacity of receiving waters. In some cases, possibly even ameliorating effects of added rising
CO
2
on pH.
Estuaries, by definition, lie between sources of freshwater and the ocean. As such, estuaries and other
coastal waters are strongly influenced by these two carbonate chemistry end-members. The relative
influence of each will have important impacts on the carbonate chemistry of these systems. On the
western margins of continents in the Northern hemisphere, deep water upwelling brings low pH water to
the surface. On the Pacific coast of the US, upwelling is connected to the observed low pH and lower than
expected aragonite saturation states in coastal surface waters (Feely et al., 2012). When combined with
rising atmospheric CO
2
concentrations and other physical, biological, and biogeochemical processes
encountered in near shore/estuarine waters, adverse pH and associated carbonate chemistry conditions can
be detrimental to commercial shellfish culturing inside and outside of hatcheries. Indeed, this is now
occurring with some frequency on the Pacific coast (Feely et al., 2012). Although deep water upwelling is
not an issue in Chesapeake Bay, the physical, biological, and biogeochemical processes that are present
result in strong fluctuations of the carbonate system at various time scales (e.g., diurnal, tidal, seasonal) in
Chesapeake Bay.
Characterizing the temporal and spatial patterns of the carbonate system in Chesapeake Bay will yield
insights on the range of carbonate chemistry conditions that contemporary biota can tolerate. Insights on
the effects of changing carbonate chemistry at ecologically relevant scales (e.g., local and regional) will
be relevant to a variety of commercial and recreational fisheries. In some instances, as with oysters, the
local carbonate chemistry may be an important consideration when determining the locations of habitat
restoration. By extension, conditions may affect the success of oysters and other shellfish that are reared
in the natural environment. Given the close ties between shellfish hatcheries and their immediate natural
environments (i.e., the quality of the natural water supplies to hatcheries) the possibility of changes in
water quality should be contemplated.
Other expected changes such as sea level rise, increasing water temperature, changes in salinity
distributions, and changes to current patterns/volumes of rainfall in Chesapeake Bay and its watershed
will also need to be taken into consideration.
The following information will be critical for understanding acidification processes in Chesapeake Bay:
1.
Determine the Bay-wide patterns of pH, pCO
2
, dissolved inorganic carbon (DIC = TCO
2
), TA
and CO
2
fluxes at the air:water interface. Measurements should capture daily and seasonal
variation.
2.
Understand the biogeochemical and physical controls on carbonate system fluxes across the key
interfaces of land:estuary, ocean:estuary, soil/sediment:water (see Fig. 1).
3.
Link CO
2
/DIC fluxes to photosynthesis, respiration and the metabolic balance of these in order
to understand which biological processes are forcing the carbonate system.
4.
With respect to acidification, put Chesapeake Bay in the larger context of estuaries of the world
as a net CO
2
source, sink, or both.
