Comparison of Mid-Bay and Lateral Station Water Quality Data in the Chesapeake Bay Mainstem
Report outlining comparisons of selected lateral and mid-Bay stations in the Chesapeake Bay mainstem to see if they have the same overall levels of certain water quality parameters.
Description
Seasonal median water quality values were compared between stations in mid-Bay and lateral regions in seven east-west transects in the mainstem Chesapeake Bay. Comparisons were made over seven years, 1985-1991, for April-October surface layer medians of total phosphorus, total nitrogen, dissolved orthophosphate, dissolved inorganic nitrogen, total suspended solids, chlorophyll a, Secchi depth, and salinity. Comparisons were also made using spring (March-May) and summer (June-September) medians of surface and bottom salinity and dissolved oxygen. Comparisons were made using difference plots of raw data, scatter plots of annual seasonal medians, and the Wilcoxon matched-pairs test on annual seasonal medians. The graphical and statistical analyses confirmed each other. Correlation coefficients were also calculated between mid-Bay and lateral data series to estimate their degree of similarity over time, but could not be tested for statistical significance.