Maryland Trends Discussion
Statistically significant B-IBI trends (p<0.1) were detected at 12 of the 27 sites currently monitored for trends. Trends in benthic
community condition declined at 8 sites (significantly decreasing B-IBI trend) and improved at 2 sites. Two trends were new in
2011, both improving.
Sites with improving benthic condition were located in the Bay main stem (Station 26), Potomac River at Maryland Point
(Station 40), lower Choptank River (Station 64), and Back River (Station 203). Sites with declining benthic condition
were located in Baltimore Harbor (Station 22), Curtis Creek (Station 202), Patuxent River at Holland Cliff (Station 77),
Patuxent River at Broomes Island (Station 71), tidal fresh Potomac River (Station 36), mesohaline Potomac River at
Morgantown (Stations 43 and 44), and Nanticoke River (Station 62).
The most important changes in 2011 were the appearance of an improving B-IBI trend in the Potomac River at
Maryland Point (Station 40) and the re-appearance of the improving trend in the lower Choptank River
(Station 64) that disappeared last year. Using the last three years of data, the average B-IBI score
remained about the same for most sites, increased at 3 sites, and declined at 5 sites. However, B-IBI
scores increased at 13 sites in 2011, indicating better overall benthic community condition in 2011 than
in the previous year. There was an increase in abundance and species numbers at many of the fixed sites
in 2011. This increase may have been related to very low salinities during the summer of 2011 which were
preceded by unusually high river flows in the spring and early summer. Species that showed increased
abundance were low salinity estuarine species that typically respond quickly to favorable conditions
through high reproductive output. Fixed sites in the deep Potomac River, from Maryland Point to St. Clements
Island, were affected by severe hypoxia in 2011 and did not show this pattern of increased abundance.