David A. Flemer's research while affiliated with United States Environmental Protection Agency and other places

Publications (49)

Article
The Susquehanna River annually supplies about 8.4 × 104 and 4.7 × 103 metric tons of particulate carbon (PC) and nitrogen (PN), respectively, to upper Chesapeake Bay. In the upper bay, the concentration of PN usually ranges between 0.10 and 0.30 mg liter−1 and is occasionally greater than 0.50 mg liter−1. In the lower study area, the concentration...
Article
Freshwater inflow is central to the definition of estuaries and if we lose control of the quantity of freshwater flow or discharge (including seasonal timing) to estuaries, then freshwater water quality has the potential to become a moot issue in estuarine ecosystems (Definition of estuaries: estuaries (aestus = tide) are physico-chemically, geomor...
Article
We tested the effects of four different sediment types collected from northern Gulf of Mexico estuarine systems on macroinfaunal colonization and community development in our laboratory flow-through microcosm system. Four sediments, types included , a beach sand, two fine-grained muds, but from different locations, and a 50:50 mixture of one of the...
Article
Full-text available
Microzooplankton dilution grazing experiments were conducted with water collected from Pensacola Bay, Florida (USA) on 12 dates at 2 sites. Statistically significant grazing rates were observed in 22 of 24 experiments. Grazing rates in Upper Bay and Lower Bay were similar averaging 0.54 and 0.51 d−1, respectively. Phytoplankton growth rates were al...
Article
Full-text available
Nutrient limitation bioassays were conducted on six dates from November 1998 to September 1999 at two sites, including oligohaline (Upper Bay) and mesohaline regions (Lower Bay), in Pensacola Bay, Florida. Phytoplankton growth responses (measured as changes in chlorophyll a concentration) to inorganic nitrogen (N) and phosphorus (P) additions were...
Article
Seasonal patterns (i.e., December 1986, and April and October 1987) in benthic macroinfaunal abundance,distribution, and taxa composition at 19 sites in Perdido Bay, AL/FL, are evaluated to assess the relative importance of environmental factors as determinants of community structure. A total of 46 taxa from five phyla were collected with diver-hel...
Article
The three-season average of sediment potential denitrification rates (PDRs) (i.e., NOâ⁻ saturated; acetylene blockage method) for five study areas within urban bayous and bays in the Pensacola Bay area, Florida, ranged between 43 and 223 nmol of N g⁻¹ h⁻¹. Average PDRs extrapolated to a unit area basis approximated 500 to 1000 μmol of N mâ...
Article
A study of nutrient limitation of phytoplankton biomass production with emphasis on nitrate-nitrogen (NO3 −) and ortho-phosphate-phosphorus (PO4 3−) was conducted in Perdido Bay, Alabama-Florida. The experimental design employed 18-1 outdoor microcosms operated in a static renewal mode. Phytoplankton growth responses (i.e., growth stimulation) meas...
Article
A 42-d flow-through experiment was conducted to evaluate the effects of the organo-phosphate pesticide, chlorpyrifos, and microcosm size (small: 144 cm2; large: 400 cm2) on benthic estuarine macroinvertebrate colonization. Nested central and perimeter (outside margin) cores were used to assess animal distribution within microcosms. Fine-grained, or...
Article
We examined marine benthic macroinvertebrate colonization and community structure at multiple spatial scales (study areas, reference and disposal sites, and depth zones within sites) within a 3-day period at three relatively widely separated (ca 60 km) dredged material disposal areas (Mermentau and Atchafalaya Rivers and Freshwater Bayou) in coasta...
Article
Two six-week laboratory experiments were conducted to evaluate effects of pesticides and microcosm size on benthic estuarine macroinvertebrate recolonization. Sediments fortified with the pesticides (fenvalerate: controls, 5 (low) and 50 µg g−1 wet sediment (high); endosulfan: controls, 1 (low) and 10 µg g−1 wet sediment (high)) were fine-grained,...
Article
Microcosms containing defaunated, fine estuarine sediments were field deployed to assess the effects of microcosm size on the rate of benthic macroinvertebrate recolonization and resulting community structure. Four sizes of microcosms (square acrylic plastic boxes: 7 cm side−1, 12 cm side−1, 20 cm side−1, and 32 cm side−1, all 6-cm deep) were deplo...
Article
Five laboratory studies of benthic macroinvertebrate recolonization were conducted for six‐week periods to evaluate the effects of physical scaling factors (i.e. microcosm size, seawater flow rates and sediment depth) on benthic community structure. Design variables included four open‐faced acrylic containers of size‐7, ‐12, ‐20 and ‐32 cm/side; se...
Article
The structure of a macrobenthic invertebrate community associated with the seagrass, Thalassia testudinum, was evaluated under laboratory and field conditions. The research focused on: (1) the effects of pollution stress from a representative drilling fluid used in offshore oil and gas operations, and (2) a comparison of responses of the seagrass-i...
Chapter
During October, 1972 the Patuxent River Estuary was monitored intensively and synoptically over two tidal cycles to determine the spatial and temporal patterns of various hydrodynamic, chemical and biological features. Forty-one depths at eleven stations along nine transects were sampled simultaneously at hourly intervals for salinity, temperature,...
Article
A comparative study of the standing crop of marsh vegetation was made of the Patuxent River and Parker Creek, two tributaries of Chesapeake Bay. The biomass of marsh vegetation in the tidal freshwater and brackish regions of the Patuxent was relatively uniform with regard to salinity, seasonally high concentrations of dissolved nitrogen, and phosph...
Article
The authors have endeavored to create a verified a-posteriori model of a planktonic ecosystem. Verification of an empirically derived set of first-order, quadratic differential equations proved elusive due to the sensitivity of the model system to changes in initial conditions. Efforts to verify a similarly derived set of linear differential equati...
Chapter
Two irregularly flooded brackish marshes of the Chesapeake Bay estuarine system were studied to detect patterns of tidal nutrient exchange and utilization. A 5.7 ha marsh on the Choptank River was monitored monthly from October 1974 to August 1975 for dissolved inorganic nitrogen and phosphorus. During these diurnal samplings, nutrient exchange wit...
Chapter
The seasonal pulsing of flows of carbon from tidal marshes results in similarly pulsed production of zooplankton in some estuaries. Direct evidence, experimental feeding of laboratory copepods, and measurements of feeding by captured wild copepods, supports the hypothesis that detritus is rapidly incorporated into higher trophic levels.
Article
The effect of entrainment on estuarine phytoplankton was studied at three steam electric stations located on tributaries of Chesapeake Bay. In most cases, chlorine rather than heat was implicated as the most important factor in the reduction of the rate of carbon assimilation. The reduction of carbon assimilation in the mixture of a plant effluent...
Article
A variety of detrital foods derived from marsh plants were fed to the copepods Eurycemora affinis and Scottolana canadensis. The copepods did not survive well or produce eggs when feeding on detritus with smaller amounts of microbiota, but did well when a rich and abundant microbiota was present. Ciliated protozoans appear to be particularly import...
Article
Flows of particulate carbon, nitrogen, phosphorus, chlorophyll a, crude fiber, carbohydrate, and adenosine tri-phosphate; and of dissolved nitrogen and phosphorus between a marsh and the Patuxent estuary, Maryland, USA, were measured over a 2-year period. Virtually no carbon was exchanged, while net flows of nitrogen and phosphorus were from the ma...
Article
Seston, particulate carbon, relative irradiance and Secchi disk depth measurements were taken at eight stations in the esturaine portion of the Patuxent River for two years. Seston values in the central portion of the estuary were high as a result of resuspension in the “sediment trap.” In this estuary, seston concentration cannot be precisely esti...
Article
The production of algae in the Patuxent River estuary (Maryland, USA) was much less than the carbon requirements of a population of the calanoid copepod Eurytemora affinis. Detrital carbon was present in quantities that suggest turnover times of 8 to 83 days for this pool, assuming that all algal production was consumed by E. affinis. We hypothesiz...
Article
The distribution and productivity of nannoplankton and net plankton were surveyed at one station in a temperate estuarine area through 1.5 year cycle at 1, 15 and 31 m depths. Nannoplankton cell numbers were more abundant than net plankton during all seasons at all depths except at 15 and 31 m during November–January and at 31 m during August. Vari...
Article
Water samples “quick-frozen” in an acetone-dry ice bath may become contaminated with acetone, even though tightly sealed in screw-cap polyethylene bottles. Acetone interferes with oxidation steps in ammonia and total phosphorus analyses, as well as the oxidative determination of dissolved organic carbon. Samples taken for such purposes should not b...
Article
The major sources and sinks of suspended particulate carbon are identified for northern Chesapeake Bay, Maryland, USA. The area of the bay under consideration was divided into two sections. The northernmost section (upper bay), from the head of the bay to the vicinity of Baltimore, was characterized by a high input of particulate carbon from upland...
Article
Ten daylight incubator estimates of primary production were performed at the mouth of the Patuxent estuary, Maryland, during the warm season of 1967. Daytime gross and net photosynthesis ranged from 1.10 to 3.75 and −0.39 to 2.57 g C m−2 respectively. An assumed photosynthetic quotient of 1.0 was required to usually give positive estimates of 24-hr...
Article
Short-term variations in fluorescence and dissolved oxygen were recorded from a fixed station between 6 and 7 m over 12 m of water in upper Chesapeake Bay. The late afternoon curves showed a positive relationship and the early evening curves exhibited an inverse correspondence. The observed oscillations could result from internal waves but the vari...
Article
Primary production of the North Branch of the Raritan River was measured at three sites by the diurnal oxygen curve method. An effluent of treated domestic sewage entered the river between the uppermost station (I) and the intermediate station (II). Mean gross productivity at Station I from May to September 1962 was 4.7 g O2 m–2 day–1 (n = 8). In c...
Article
Steam electric stations may reduce primary production of cooling water by 91 percent as a result of chlorine applications for control of fouling organisms. Bacterial densities and concentrations of chlorophyll a are also reduced. Slight stimulation of production may occur in the absence of chlorination. Based on the available supply of "new" water,...
Article
Estimates of annual primary production and standing crops based on chlorophylla were made in the northern half of Chesapeake Bay over a 160 km section. Both the chlorophylla concentrations and incubator productivity were maximum during the warmer season, especially in the oligohaline area. The higher salinity waters usually showed lower values of b...
Article
The fluorometric method was used to obtain a continuousin vivo record of chlorophylla distribution in surface waters of the mid-Chesapeake Bay. Measurements were made just previous to and during a fall dinoflagellate bloom. Chlorophylla values computed from calibration curves ranged from 10 to 56 mg m−3. Off-scale values as high as 167 mg m−3 were...
Article
In ecological effects of nuclear steam electric station operations on ; estuarine systems. Volume II.;
Article
Full-text available
A post-Agnes study that emphasized environmental factors was carried out on the Patuxent R iver estuary with weekly sampling at eight s tations from 28 June to 30 August 1972. Spatial and temporal changes in the distribution of many factors, e.g., salinity, dissolved oxygen, seston, particulate carbon and nitrogen, inorganic and organic fractions o...
Article
In ecological effects of nuclear steam electric station operations on ; estuarine systems. Volume I. The results of field work that was completed ; between September 27, 1971 and March 15, 1973 are summarized. The objective of ; the field work was to document the seasonal and spatial distribution of the ; standing crop of phytoplankton and the pote...

Citations

... Apparently, little of the plant material is used directly by herbivores within the marsh (29). Some of the marsh grass appears to be used as a substrate for microbial colonization, with the microbial species in turn serving as food sources for many macroconsumers (17,26). The relative significance of soluble versus particulate materials as substrates has not been established. ...
... T h e distribution of conserved quantities may reflect differences in tidal advection (Dyer & Ramanoorthy, 1969), the influence of bathymetry (Ingram, 1976), meteorological events (Elliot & Wang, 1978), varying freshwater flows (Garvine, 1975), o r other dynamic effects (Smith, 1978(Smith, ,1980). In addition, for nonconservative properties, local in situ sources and sinks may contribute to 584 T. M. Powell et al. ----the observed distributions (Ulanowicz & Flemer, 1978). Previous measurements of the patterns of physical parameters in estuaries, such as spatial variability in the salinity and velocity fields, have been conducted with the aim of evaluating the longitudinal salt flux (Dronkers & van de Kreeke, 1986), or the dynamic balance (Pritchard, 1952(Pritchard, ,1956Dyer, 1973). ...
... Although early Chesapeake Bay studies of nutrient fluxes in marsh tidal creeks failed to show clear patterns of nutrient removal at tidal scales (e.g. Heinle & Flemer 1976, Stevenson et al. 1977), recent measurements and mass-balance analyses suggest that Bay marshes can be major nutrient sinks. For example, particulate N and P trapped in marshes of the tidal fresh Patuxent represent 35% and 80% of the respective inputs to the upper estuary (Merrill & Cornwell 2000 ). ...
... In general, estuaries and bays in this region are lagoons, or coastal embayments, with barrier islands (Glibert et al. 2010). Mean tidal amplitude and periodicity differ between sites (0.3 -1.6 m), with most exhibiting micro-or mesotidal, mixed semi-diurnal, or diurnal tides (Pingree andGriffiths 1980, Godin 1987). ...
... The primary experiment involved a 6 wk study (31 January to 15 March 1996) Edmondson (1955), Perez et al. (1977), Ringelberg & Kersting (1978), Heinle et al. (1979), Painting et al. (1989) b Oviatt et al. (1984), Levin (1986), Oviatt et al. (1986), Rudnick & Oviatt (1986), Goldsborough & Kemp (1988), Sampou & Oviatt (1991) c Raymont & Miller (1962), Gamble et al. (1977), Grice et al. (1980), Doering & Oviatt (1986), Burkholder et al. (1992), Neundorfer & Kemp (1993) d Refer to for complete list tems were randomly separated into 2 groups, one treated and one serving as a control. Material was removed from the wall surfaces of treated mesocosms at twice-weekly (3 to 4 d) intervals, while material was allowed to accumulate on the walls of control systems throughout the experiment. ...
... Previous studies have observed washouts of estuarine plankton during storms, resulting in immediate decreases in their biomass, with the most common parameter documenting this phenomenon being Chl a (i.e., Flemer et al. 1977; Alpine and Cloern 1992; Eyre 2000; De Carlo et al. 2007). In Hilo Bay, Chl a concentrations decreased immediately following storms. ...
... Most of the existing researches focus on the dominant species, community structure, influencing factors, diversity characteristics of macroinvertebrates and the role of macroinvertebrates in ecological environment assessment in a single coastal wetland ( Warwick et al., 1991 ;Chainho et al., 2007 ;Dauvin et al., 2009;Yu et al., 2012 ;Morais and Lee, 2014 ;Shi et al., 2014 ;Noman et al., 2019 ). It has been pointed out that the environmental factors affect their diversity and directly lead to the changes of macroinvertebrate taxa composition in coastal wetlands ( Flemer et al., 1998 ;Vale et al., 2010 ;de Juan and Hewitt, 2011 ). At present, the identification of major environmental factors and analysis of their impact on the dominant species and species diversity of macroinvertebrates in coastal wetlands are still lacking systematic review at the regional scale. ...
... Nitrate is the prime plant nutrient, and raising its content might increase water eutrophication. High nitrate contents may be accompanied by high chloride concentrations in areas of organic pollution (Flemer et al., 1998). In this study, all nitrate levels were much lower than the allowed maximum nitrate concentration of 2.93mg/L (CCME, 2017), where the nitrate values (NO 3 -N) ranged from 63.75µg/L at site 3 in summer to 850.36µg/L at site 5 during winter, with averages of 402.37 and 207.25µg/L in winter and summer, respectively. ...
... Sediments used in the recolonization experiment were collected from San Felipe Channel (gross sand) and San Amaro Beach (fine sand) using a van Veen grab. Sediments were defaunated using a combination of the techniques used by Flemer et al. (1993), Ruth et al. (1994) and Colangelo and Ceccherelli (1994); the sediment was frozen during 3 days and then exposed to heat (40 C). The process was repeated twice. ...
... The concentrations of LMW PAH and HMW PAH were higher than TEL values in the four coastal lagoons (P50% of sites) in accordance with Long et al. (1995) and Macdonald et al. (1996); concentrations of PAHs were also high in Dzilam and Ria Lagartos (>50% of sites). These pollutants seem not yet to have had an effect on benthic infauna, however, because P. heterobranchia and Syllis in Dzilam are typically associated with non-polluted areas (Dean, 2008;Weber et al., 1992). The high abundance of L. robustus in Ria Lagartos could be explained by the fact that some capitellids, orbinids and spionids can tolerate low levels of oil hydrocarbons (Bonsdorff et al., 1990). ...