Assessment and significance of phytoplankton species composition within Chesapeake Bay and Virginia tributaries through a long-term monitoring program

Abstract

Phytoplankton and water quality long term trends are presented from a 20-year monitoring program of Chesapeake Bay and several of its major tributaries. Increasing phytoplankton biomass and abundance are ongoing within this estuarine complex, with diatoms the dominant component, along with chlorophytes and cyanobacteria as sub-dominant contributors in the tidal freshwater and oligohaline regions. Diatoms, dinoflagellates, and cryptomonads are among the major flora downstream in the tributaries and within the Chesapeake Bay. Water quality conditions within the three tributaries have remained rather stable over this time period; while there are long term trends of reduced nutrients, increasing bottom oxygen, and decreasing water clarity for the lower Chesapeake Bay. Of note is an increasing trend of cyanobacteria biomass at 12 of the 13 stations monitored at tributary and Chesapeake Bay stations, plus the presence of 37 potentially harmful taxa reported for these waters. However, the overall status of the phytoplankton populations is presently favorable, in that it is mainly represented and dominated by taxa suitable as a major food and oxygen source within this ecosystem. Although potentially harmful taxa are present, they have not at this time exerted profound impact to the region, or replaced the diatom populations in overall dominance.

Factors Determining the Location of the Chlorophyll Maximum and the Fate of Algal Production within the Tidal Freshwater James River

“…However, our average mesozooplankton filtration rate was very similar to the nearby Potomac River (5.4 μl −1 ind −1 h −1 ) where low filtration rates were attributed to the presence of cyanobacteria (Sellner et al 1993). Biomass of cyanobacteria has increased significantly in the tidal freshwater James River during the past 20 years (Marshall et al 2009). Average densities of cyanobacteria (principally Merismopedia, Anabaena and Microcystis) at the CHLa maximum were 157 million cells L −1 during our study (H. Marshall, unpublished data) and exceeded those reported for the Potomac (86 million cells L −1 ; Sellner et al 1993).…”

Community composition and activity state of estuarine bacterioplankton assessed using differential staining and metagenomic analysis of 16S rDNA and rRNA

“…Prominent taxa in our samples were typical of the freshwater environment, with a few exceptions. For example, we observed a high prevalence of Cyanobacteria, supporting previous work showing that density of Cyanobacteria is higher in the tidal-freshwater James River than in other Chesapeake Bay tributaries (Marshall et al 2009). In contrast, although Bacteroidetes are common in other studies, the prevalence of Sphingobacteria in our environmental samples was unusually high.…”

Temporal pattern prevails over spatial variability in phytoplankton communities from a subtropical water supply reservoir

“…Previous studies of composition and dynamics in phytoplankton communities were often restricted to single dimensions, and focused on time series, depth profiles or horizontal surveys across environmental gradients (Figueredo, Giani 2001;Marshall et al 2009;Yang et al 2011Yang et al , 2012. In this study, phytoplankton communities in Dongzhen Reservoir were investigated in three dimensions: spatial variation from riverine, transitional and lacustrine zones, different depths from surface to deep layers, and temporal variation through four seasons in the annual cycle (Fig.…”