Product Citations and Abstracts

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-held bottom corers. Polychaetes were numerically dominant followed by crustaceans. Seventeen taxa co-occurred in samples during all three study periods. Highest densities occurred in April throughout the bay, reflecting a fall-spring recruitment. Deeper upper bay stations were depauperate during December and October. Low dissolved oxygen (DO) largely explained the depauperate pattern. Mean taxa richness per core ranged from 0.0 to 5.0, 1.2 to 4.6, and 0.0 to 4.4 in December, April and Octrober, respectively. Mean densities ranged from zero to 368, 0 to 960, and 0 to 430 individuals per 0.1 m2 in December, April, and October. Results of a three-season statistical regression model indicated that DO deficiency was a primary determinant of taxa richness (partial R2:0.27) but was less important in explaining animal densities (partial R2:0.16). For December, when additional environmental variables were measured, DO was supplanted by weight loss on ignition (R2:0.24) and the sediment C:N ration (R2:0.44) as highest explanatory factors for taxa richness and density, respectively. Application of a benthic index of environmental condition indicated wide-spread ecological stress on the benthic macroinfaunal assemblages.

Flemer, David A., Barbara F. Ruth and Charles M. Bundrick. 2002. Effects of Sediment Type on Macrobenthic Infaunal Colonization of Laboratory Microcosms. Hydrobiologia. 485(1-3):83-96. (ERL,GB 1080).

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 mud sediments and beach sand. Our hypothesis was that the pattern of colonization would differ among sediment types based on empirical field data and theory but the differences would be expressed most strongly at sediment type extremes (e.g., mud versus sand). A total of 49 taxa colonized the four sediments. Unidentified Actiniaria (sea anemones) numerically dominated densities among all four sediments with densities ranging between 46.5 to 60.5 per microcosm (20 cm side-1). Average taxa richness per microcosm (N:10 replicates per sediment treatment) ranged from 10.4 in one of the mud treatments to 14.9 taxa in the sand. These were the only significant differences among sediment types ( P less than or equal to 0.05) in taxa richness and we detected no significant effects of sediment type on animal densities. Differences in community metrics, although statistically significant, were generally of a relatively small magnitude. Five of 10 microcosms per treatment were randomly selected to test for effects of sediment depth (e.g., top, mid, and bottom). In vertically sectioned microcosms, average taxa richness in sand treatments was significantly greater than those of the other three sediments. A non-parametric multivariate analysis (Primer) revealed that community structure in the vertically sectioned microcosms differed significantly between sand and one of the mud treatments. Mean taxa richness of top sections differed significantly from mid and bottom sections. We detected significantly higher animal densities and taxa richness ( p less than or equal to 0.05) in vertically sectioned versus non-sectioned microcosms. However, these differences were unexplained based on experimental protocols.

Flemer, David A., Thomas W. Duke and Foster L. Mayer, Jr. 1986. Integration of Monitoring and Research in Coastal Waters: Issues for Consideration from a Regulatory Point of View. In: IEEE Oceans '86 Conference Proceedings. EPA/600/D-86/214. Institute of Electrical and Electronics Engineers, New York, NY. Pp. 980-992. (ERL,GB 581). (Avail. from NTIS, Springfield, VA: PB87-102521)

Coastal marine ecosystems are characterized by a high degree of natural variability. The weak resolving power of marine science to differentiate between effects ascribable to natural factors versus human intervention often leads to unrealistic expectations of "goods and services" that these ecosystems can provide. This high uncertainty often contributes to faulty communication among scientists, resource managers and the public. We believe that this problem is further enhanced by misunderstandings of the need to integrate monitoring and research. We explain why monitoring is a retrospective activity and the principal way it can become a prospective activity is through hypothesis framing, testing,and modeling. We describe the logic that underpins a program designed to characterize the limits of applicability of extrapolation from laboratory data to the field. This interactive, iterative process couples concepts of monitoring and research so that the research question and method are linked to spatial and temporal scales of ecological variability. Without such considerations, important ecological relationships remain unspecified, thus precluding meaningful approaches to management of such complex but valuable ecosystems.

Flemer, David A., Virginia K. Tippie, Gail B. Mackiernan, Robert B. Biggs, Willa Nehlsen and Kent S. Price. 1987. Characterizing the Chesapeake Bay Ecosystem and Lessons Learned. In: Estuarine and Coastal Management - Tools of the Trade: Proceedings of the Tenth National Conference of The Coastal Society, October 12-15, 1986, New Orleans, LA. EPA/600/D-87/071. The Coastal Society, Bethesda, MD. Pp. 153-177. (ERL,GB 594). (Avail. from NTIS, Springfield, VA: PB87-166930)

During the scientific study phase, the U.S. Chesapeake Bay Program examined the complex ecological structure and processes of the Bay estuary in a coherent and manageable framework. The framework was supported by a rational spatial scaling or segmentation, with an implicit temporal scale. The historic geological, physical, chemical (water quality), and biological data were analyzed within this framework to determine trends, correlations and, where appropriate, causal relationships. The overall process resulted in a synthesis or statement on the environmental condition of the Chesapeake Bay ecosystem. We provide an explanation of the strengths and weaknesses of the approach and suggest improvements in future efforts of this type.

Flemer, David A., James R. Clark, Roman S. Stanley, Charles M. Bundrick and Gayle R. Plaia. 1993. Importance of Physical Scaling Factors to Benthic Marine Invertebrate Recolonization of Laboratory Microcosms. EPA/600/J-94/114. Int. J. Environ. Stud. 44:161-179. (ERL,GB 804). (Also avail. from NTIS, Springfield, VA: PB94-155538)

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; seawater flow rate--approximately 0.7 or 1.6 liters/min; and sediment depth of 2.5 or 5.0 cm. Response variables included: total number of organisms (TNO), and taxa (TNT) and dominant taxa. Effects of seawater flow rates were more apparent than those related to microcosm size and sediment depth. Both TNO and TNT gave significant positive responses to increasing flow. Size effects were non-linear; size-20 microcosms tended to average more organisms than size-32 but effects were often not significant (P>0.05). Size-20 microcosms averaged higher numbers of taxa than size-32 and responses were usually significant (P<0.05). Dominant taxa in these experiments were the tunicates, Molgula sp. And Didemnum sp., and amphipod, Corophium acherusicum, a bryozoan, Bugula neritina, and the bivalves, Cumingia tellinoides and Laevicardium mortoni. Below the fourth rank, dominant taxa varied greatly among treatments. In a number of cases, individual taxa were in sufficient abundance to test for taxa-specific effects. Relatively rare taxa (e.g. taxa containing 1 to 7 individuals within an individual experiment) frequently accounted for 60% of the total number of taxa. Statistical power analysis based on a representative data set of non-mobile macroinvertebrates which provided an increased number of degrees of freedom detected a 20% difference from the means of response variables but a doubling or larger sample size would be required to detect a 10% difference at a power >or= 0.9 for an alpha=0.05. These results help provide a basis for setting minimum experimental unit parameters and should lead to cost savings through physical scale reduction (depth of sediment and surface area) and less time to process smaller volumes of sediment and generation of smaller volumes of waste water.

Flemer, David A., Roman S. Stanley, Barbara F. Ruth, Charles M. Bundrick, Paul H. Moody and James C. Moore. 1995. Recolonization of Estuarine Organisms: Effects of Microcosm Size and Pesticides. EPA/600/J-95/375. Hydrobiologia. 304:85-101. (ERL,GB 857).

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 mg-1 wet sediment (high); endosulfan: controls, 1 (low) and 10 mg g-1 wet sediment (high) were fined-grained, organically rich (approximately 3.5% organic carbon and 22% dry weight) material. Relative dominance of the four most abundant taxa in both experiments was consistent amongtreatments with few exceptions. The amphipod, Corophium acherusicum, dominated abundance in both experiments. In the fenvalerate experiment, large trays (400 cm2) contained significantly (p<0.05) more total number of taxa (TNT) than small microcosms (144 cm2) but tray size was not significantly related to total number of organisms (TNO). When size was adjusted to a common unit area, small trays was 2.5 times that of large containers; a ratio close to that of microcosm sizes (i.e., 2.8). This result suggests that larval supply may have been inadequate to 'saturate' the available sediment in large containers. Fenvalerate significantly reduced abundance in the high treatment compared to both controls and low treatment but low treatment was not significantly different from controls. The amphipod; Corophium acherusicum, accounted for most of the decrease in abundance in response to fenvalerate. The holothruroid, Leptosynpta sp. and the polychaete, Mediomastus ambiseta, increased in abundance significantly with increased concentration of fenvalerate. Combined effects of actual microcosm size and concentration of endosulfan were not significant for TNO or TNT. As in the fenvalerate experiment, adjusted abundance of small microcosms was 2.6 times that of large trays which approximated the ratio of unit area between microcosm sizes. Abundance of a few taxa responded significantly to adjusted and unadjusted area. Abundance of the tunicate, Molgula manhattensis, increased significantly with increased concentration of endosulfan. Abundance was affected by sample location (e.g., interior vs exterior cores) within microcosms. Abundance adjusted to unit area resulted in significantly greater TNO in external vs internal cores. This has improtance for sequential sub-sampling of microcosms to determine temporal dynamics. Statistically significant effects were measured in benthic community structure associated with microcosm size; however, the magnitude was relatively small. There appears to be no major biological reason to select one microcosm size over the other for screening for contaminant effects. Where feasible, the small trays provide savings in sample preparation and analysis, allow more replicates where laboratory space is limiting and generate less chemical waste. These benefits may be off-set by less 'artifacts' associated with edge effects of larger microcosms and the need for a larger mass of sediment to accommodate additional analytical requirements (e.g., thin vertical surficial samples to refine contaminant exposure at the sediment/water interface.

Flemer, David A., Barbara F. Ruth, Charles M. Bundrick and James C. Moore. 1997. Laboratory Effects of Microcosm Size and the Pesticide Chlorpyrifos on Benthic Macroinvertebrate Recolonization of Soft Estuarine Sediments. Mar. Environ. Res. 43(4):243-263. (ERL,GB 951).

A 42-d flow-through experiment was conducted to evaluate the effects of the organophosphate 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, organically-rich (approximately 4.0% organic carbon and 20% dry wt) sediments were nominally fortified with chlorpyrifos controls, low (1.0) and high treatments (10.0 µg-1 wet sediment). Large microcosms contained a significantly (p<0.05) higher average taxa richness (10.9) than small microcosms (8.6) but small microcosms contained a significantly greater average animal density (295.8; numerical abundance adjusted to unit area) than large microcosms (120.5). Density of the polychaete, Neanthes succinea, the amphipod, Corophium acherusicum, and the barnacle, Balanus sp., was signficantly greater in small microcosms but density of Ensis minor was significantly greater in large microcosms. In small and large microcosms, respectively, densities averaged significantly greater numbers in perimeter cores (e.g. 203.1 and 75.1) vs central cores (71.9 and 45.4). Average density decreased significantly with increasing chlorpyrifos concentration from controls (326.8), to low (123.8) and high (78.8) treatments. The density decrease was significantly related only to C. acherusicum whose densities decreased from controls (258.8) to low (88.5) and high (43.9) dosed microcosms. Application of an equilibrium partitioning model indicated that density of C. acherusicum was sensitive to an estimated interstitial water concentration of approximately 0.48 µg liter-1. Non-metric multidimensional scaling ordination analyses provided important insights into response patterns not available through ANOVA procedures. A permutation procedure (ANOSIM) detected a significant size effect (p<0.0001) and a significant effect between controls and low (p<0.042) and high doses (p<0.013) but not between low and high chlorpyrifos treatments (p<0.465). A single species, C. ascherusicum, as in the ANOVA analyses, dominated contributions to community average percent dissimilarity in most combinations of microcosm size and chlorpyrifos treatment effects (range:8.4-21.9%). Community structure differed significantly in several combinations of microcosm size, core position and chlorphyifos treatment. Results confirm earlier work that intrinsic design factors influence benthic macroinvertebrate community structure and determine taxa available to pesticide exposure in microcosms.

Flemer, David A., Robert J. Livingston and Sean E. McGlynn. 1998. Seasonal Growth Stimulation of Sub-Temperate Estuarine Phytoplankton to Nitrogen and Phosphorus: An Outdoor Microcosm Experiment. Estuaries. 21(1):145-159. (ERL,GB 966).

A study of nutrient limitation of phytoplankton biomass production with emphasis on nitrate-nitrogen (NO3-) and ortho-phosphate-phosphorus (PO43-)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) measured as chlorophyll a (chl a) fell into three principal categories: primary P stimulation occured mostly during the cooler months at the upper bay (tidal brackish) and mid bay (lower mesohaline) stations; a total of 12 out of 36 experiments; primary N stimulation occurred mostly during the warmer months primarily at the mid-bay station and infrequently at the upper and lower bay stations (upper mesohaline); a total of 7 out of 36 experiments; and N+P co-stimulation occurred primarily during the warmer months in the upper bay and mid bay and during both warmer and cooler months in the lower bay; a total of 17 out of 36 experiments. Primary P stimulation was generally associated with high ratios of dissolved inorganic nitrogen (DIN) to dissolved inorganic phosphate (DIP) (ratio range: 18 to 288). Conversely, primary N stimulation was associated with decreasing DIN:DIP ratios (range 8-46). Redfield ratios of particulate organic N (PON) to particulate organic P (POP) often indicated N limitation (i.e., values often less than 10). PON:chl a ratios often indicated N sufficiency, but three occasions were noted where PON:POP and PON:chl a ratios often indicated N sufficiency, but three occasions were noted where PON:POP and PON: chl a ratios were not congruent. It is difficult to reconcile the inorganic and organic N and P ratios with the relatively low DIP and DIN concentrations. The phytoplankton assemblage appeared not to be strongly nutrient-limited but, given a nutrient increase, responded differentially to N and P, both seasonally and along the longitudinal salinity gradient. Grazing pressure in concert with nutrient limitation was advanced as an hypothesis to explain N+P co-limitation.

Flemer, David A., Emile M. Lores and Charles M. Bundrick. 1998. Potential Sediment Denitrification Rates in Estuaries of Northern Gulf of Mexico. J. Environ. Qual. 27(4):859-868. (ERL,GB 991).

The three-season average of sediment potential denitrification rates (PDRs) (i.e., NO3- 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 Ng-1h-1. Average PDRs extrapolated to a unit area basis approximated 500 to 1000 µmol of Nm-2h-1 that are relatively high values but comparable to those where conditions for denitrification are favorable. A regression model, based on a larger number of measured environmental factors for the spring than fall and winter indicated that NO2- + NO3- concentrations explained most of the total variability (R2:27%; P<0.003) in PDRs. The NO2- + NO3- concentrations were also predictive of PDRs (R2 ranged from 0.56-0.98; all P-values <0.05) on four separate occasions for comparisons made within five study areas and three seasons. Sediment trace metal concentrations (e.g., Ni), based on published values, were high enough to cause reduction in PDRs through direct toxicity to denitrifiers at several stations. Sediment metals toxicities, based on published sediment quality guidelines, could occasionally cause a reduction in macrobenthic infaunal bioturbation and irrigation. Such a reduction could attenuate the flux of dissolved oxygen into sediments and cause a reduction in denitrification rates by limiting the coupled processes of nitrification and denitrification. Also, a reduction in the flux of NO2- or NO3 -, a substrate for denitrification, into sediments can directly limit denitrification rates.

Flemer, David A. 1989. Methods Manual for Perdido Bay Citizens Monitoring Program. EPA/600/4-89/030. U.S. Environmental Protection Agency, Environmental Research Laboratory, Gulf Breeze, FL. 28 p. (Avail. from NTIS, Springfield, VA: PB89-224927)

The Methods Manual for Perdido Bay Citizens' Monitoring Program and its companion quality assurance/quality control plan were developed in response to a request made by the Friends of Perdido Bay, Inc. (FPB). The monitoring and other activities of the FPB form an important component of the Environmental Protection Agency's Perdido Bay Cooperative Management Project (PBCMP). The PBCMP is a pilot project of the Agency's Near Coastal Water Initiative and is geographically within the Agency's Gulf of Mexico Program. Thus, data obtained by the citizens' volunteer monitoring project will be of interest to the local community and to various levels within the Agency.

In 1991, experimental transplantings of Vallisneria americana (tapegrass, vallisneria, or wildcelery) were initiated at selected sites which lacked grass beds along the north shore of Perdido Bay, located on the Alabama-Florida border. Abatement of organic and color-staining components had been implemented to improve the water quality of effluent discharged by a pulp mill into the headwaters of Elevenmile Creek, a stream entering this low salinity estuary. This study was designed to assess whether previous in situ habitat conditions (e.g., light exclusion, water or sediment toxicity) had prevented natural recruitment of aquatic grasses or if other factors, (e.g. propagule transport) existed which might limit or delay Vallisneria colonization or growth. Different experimental transplanting configurations were employed in order to observe success in establishment of beds and assess our ability to measure plant growth among the varying micro-habitats and substrates. The initial transplanting, in 1991, consisted of two plants each, spaced at 40 cm centers in four 6 x 1 m parallel row-plots. These plants subsequently spread rapidly by runners merging the rows into a continuously expanding grass bed. Second and third trials conducted in 1995, were planted in a cross-shaped configuration, which has emerged as our preferred design. The growth of these transplants indicated Vallisneria grass beds were recruitment limited, rather than constrained by prevailing conditions of water quality/toxicity, light reduction or unsuitable substrate during the study period. Our experience may represent a fundamental method for routine utilization of the responses of submerged aquatic vegetation (SAV) to assess a broad range of questions concerning habitat and water quality of potential sites for habitat restoration.

Lores, Emile M., Michael C. Murrell, Guy T. DiDonato, Roman S. Stanley, Richard A. Snyder, Jaana Sipura and David A. Flemer. Unpublished. Effects of Zooplankton Grazing on Phytoplankton Communities in Escambia Bay, FL. Mar. Ecol. Prog. Ser. Unpublished. 39 p. (ERL,GB 1119).

Phytoplankton growth, microheterotroph and mesozooplankton grazing were examined at sites in oligohaline and mesohaline regions of Escambia Bay, FL in 80 L plastic bags receiving nutrient and mesozooplankton manipulations (0 to 4X natural densities) during March and June of 1998. Depletion of inorganic nutrients and production of chlorophyll a(Chl a) and particulate C and N were followed daily. Phytoplankton accessory pigments were used as indicators of the phytoplankton community composition. Added nutrients, 15 mM N + 1 mM P, were depleted (>10%) in less than 2 days in June, however, more than 30% of the added N was still available after 7 days in March. Dilution experiments were conducted to determine the rate of microheterotroph grazing and ranged from 14% of standing crop in March to 51% of standing crop in June. Intrinsic phytoplankton growth rates ranged from 0.52 d-1 to 1.21 d-1 in March and June respectively. Mesozooplanton grazing significantly (p>0.05) decreased microzooplankton abundance in March, however manipulations of mesozooplankton appeared to affect the net phytoplankton growth by less than 5%. Mesozooplankton grazers had little effect in June due to the rapid growth of phytoplankton and poor survival of mesozooplankton. These results show that the interactions between microzooplankton and mesozooplankton are important in the structure of the estuarine phytoplankton community.

Murrell, Michael C., Roman S. Stanley, Emile M. Lores, Guy T. DiDonato, Lisa M. Smith and David A. Flemer. 2002. Evidence That Phosphorus Limits Phytoplankton Growth in a Gulf of Mexico Estuary: Pensacola Bay, FL, USA. EPA/600/J-01/437. Bull. Mar. Sci. 70(1):155-167. (ERL,GB 1131).

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, FL. Phytoplankton growth responses (measured as changes in chlorophyll a concentration) to inorganic nitrogen (N) and phosphorus (P) additions were monitored for three days. The results showed that, in 8 of 12 experiments, phytoplankton growth was stimulated by P additions in comparison with N-amended and un-amended treatments. Nitrogen additions alone did not stimulate growth over P additions in any experiment. The spatial patterns suggest that potential for P limitation was similar in Upper and Lower Bays.. The four experiments with statistically non-significant results were all conducted during winter and spring, suggesting a lower potential for nutrient limitation during the cooler months when nutrient demand (i.e. productivity) is typically low and nutrient supply (i.e. freshwater runoff) is typically high. This study adds to a small but growing literature suggesting that P limitation of phytoplankton growth may be relatively common in warm temperate estuarine systems such as those along the Gulf of Mexico coast.

Weber, David E., David A. Flemer and Charles M. Bundrick. 1992. Comparison of the Effects of Drilling Fluid on Macrobenthic Invertebrates Associated with the Seagrass, Thalassia testudinum, in the Laboratory and Field. EPA/600/J-92/408. Estuarine Coastal Shelf Sci. 35(3):315-330. (ERL,GB 753). (Avail. from NTIS, Springfield, VA: PB93-131837)

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 off-shore oil and gas operations, and (2) a comparison of responses of the seagrass-invertebrate community in the laboratory and field. A series of 15.3 cm diameter cores of the seagrass-invertebrate community was collected from field sites for establishment and sampling of microcosms and in the sampling of field plots over time. Weekly exposures to drilling fluid were conducted in the laboratory microcosms at a mean total suspended matter concentration of 110.7 mg1-1 (± 17.7 SD), and in field plots by usage of acrylic exposure chambers at a mean concentration of 132.8 mg1-1 (± 33.3 SD). Standing crop of T. testudinum was not affected by drilling fluid in the laboratory or field when measured after 6 and 12 week exposure periods. The numbers of macrobenthic invertebrates were suppressed by drilling fluid at both exposure periods in the laboratory, but inhibitory effects were absent in the field. Invertebrate densities in the field were similar among control and treated plots, and were much lower than densities occurring in the laboratory control. In most instances, species richness values were similar in the field and laboratory at the end of each 6 and 12 week period.

Champ, Michael A., David A. Flemer, Dixon H. Landers, Christine Ribic and Ted DeLaca. 1992. Roles of Monitoring and Research in Polar Environments -- A Perspective. EPA/600/J-93/382. Mar. Pollut. Bull. 25(9-12):220-226. (ERL,GB 826). (Avail. from NTIS, Springfield, VA: PB93-236214)

Researchers have been studying environmental processes in polar regions for more than 30 years. Nevertheless, the information gained has not been sufficient to provide in-depth understanding of the regions studied or most of the processes that occur there. This lack of understanding renders projections of the effects of human activities on terrestrial and marine ecosystems extremely tenuous. Some of the unanswered questions are: (1) What constitutes a significant impact in environments that are relatively unperturbed by humans? (2) What methods will minimize the environmental, health, and safety-related risks of living and working in polar regions? (3) Would the polar regions, due to their pristine nature and remoteness, serve as early warning indicators of global climate change or global pollution?

Ruth, Barbara F., David A. Flemer and Charles M. Bundrick. 1994. Recolonization of Estuarine Sediments by Macroinvertebrates: Does Microcosm Size Matter?. Estuaries. 17(3):606-613. (ERL,GB 882).

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 deployed in upper Perdido Bay, Florida, and colonized for 6 wk. Absolute mean total number of organisms (TNO) differed (a=0.05) among all sizes, while normalized mean TNO (adjusted to 12 cm side -1 area) did not. Mean total number of taxa (TNT) was different among sizes: 7 cm side -1, 12 cm side -1, and 20 cm side -1, but not between sizes 20 cm side -1 and 32 cm side -1. Seven dominant taxa occurred in all size microcosms. Scaling of physical design features (size of microcosm) affected numbers of taxa in recolonization of fine-grained sediments in our study area, but effects on abundance and dominance were minimal.

Price, Kent S., David A. Flemer, Jay L. Taft, Gail B. Mackiernan, Willa Nehlsen, Robert B. Biggs, Ned H. Burger and Dewey A. Blaylock. 1985. Nutrient Enrichment of Chesapeake Bay and Its Impact on the Habitat of Striped Bass: A Speculative Hypothesis. EPA/600/J-85/422. Trans. Am. Fish. Soc. 114(1):97-106. (ERL,GB X470). (Avail. from NTIS, Springfield, VA: PB86-208550)

Stocks of striped bass Morone saxatilis have declined in the Chesapeake Bay system over the last decade. We present evidence for the working hypothesis that the decline has resulted, in part, from loss of deep-water habitat for adults, caused by limiting concentrations of dissolved oxygen that are related, in turn, to nutrient enrichment and greater planktonic production. A related hypothesis is that changes in the near-shore habitat for juvenile striped bass, involving severe declines in submerged aquatic vegetation due to nutrient-driven planktonic shading, also have contributed to the decline of striped bass. Nutrients (nitrogen and phosphorus) and chlorophyll a, an indicator of phytoplankton biomass, have increased in many areas of the bay and tributaries over the past 20 to 30 years. These trends are qualitatively correlated with greater deoxygenation of the deep channel in the mid and upper bay. During the late 1970s, summer oxygen concentrations as low as 2 ml/liter approached to within 7-8 m of the surface, allowing water stressful to striped bass to intrude onto shoal areas of the bay. The volume of Chesapeake Bay bottom waters containing 0.5 ml O2/liter or less was about 15 times greater in July 1980 than in July 1950. The combination of the expanding hypoxic pool and summer temperatures above preferred levels for adult striped bass may contribute to an 'oxygen-temperature squeeze' that forces adults onto shoal areas of the bay or out of the upper bay. Many of these shoal areas now lack suitable cover for juvenile striped bass and their prey. Strong intraspecific competition among striped bass may be occurring there.

O'Connor, Joel S. and David A. Flemer. 1987. Monitoring, Research, and Management: Integration for Decisionmaking in Coastal Marine Environments. In: New Approaches to Monitoring Aquatic Ecosystems: ASTM STP 940. Terence P. Boyle, Editor. American Society for Testing and Materials, Philadelphia, PA. Pp. 70-90. (ERL,GB X605).

A rationale is presented for making research and monitoring interdependent to maximize the contributions of both activities to environmental management. Emphasis is placed upon better choices of temporal and spatial scales of marine assessments, thereby improving managerial guidance from monitoring and research. While appropriate scales are functions of particular environmental issues, the most useful scales 'in the mean' appear to be long-term (including truly historical) and regional. The likelihood in the near-term of only limited incremental advances in understanding ecosystem processes, with marginal improvements in predictablity, leads to an argument for more emphasis upon the use of managerially helpful, necessarily simple models. One such model is presented, to characterize the geographical prevalence of fin erosion in winter flounder (Pseudopleuronectes americanus), relative to the sources of plausible causes, from Canada to Delaware Bay. Changing emphasis from laboratory bioassays to field population-level effects is an important and essential step toward integrating ecosystem-level knowledge into the managerial and regulatory milieu. It is now possible to quantify the geographic and, at least recent, temporal associations among man's waste sources and some of their biological effects. Further elaboration of source-fate-effects understanding with the help of simple models (for example, indices) is often more useful to managers than is detailed, piecemeal quantification of seemingly intractable ecosystem dynamics.

Paul, John F., A.F. Holland, K. John Scott, David A. Flemer and Eugene P. Meier. 1989. Ecological Status and Trends Program: EPA's Approach to Monitoring Condition of the Nation's Ecosystems. In: Oceans '89 Proceedings. Vol. 2: Ocean Pollution. Institute of Electrical and Electronics Engineers, New York, NY. Pp. 579-582. (ERL,GB X628).

The U.S. Environmental Protection Agency (EPA) is initiating an Environmental Monitoring and Assessment Program (EMAP) to monitor the status and trends of the nation's near coastal waters, forests, freshwater wetlands, surface waters, and agroecosystems. This program is also intended to evaluate the effectiveness of Agency policies at protecting ecological resources occurring in these systems. Monitoring data collected for all ecosystems will be integrated for national status and trends evaluations. The near coastal component of EMAP consists of four ecosystem categories: estuaries, wetlands, coastal waters, and Great Lakes. Near coastal ecosystems will be regionalized and classified, an integrated sampling strategy designed, and quality assurance/quality control procedures and data base management procedures implemented. A pilot study will be conducted in one region of the country, followed by a full-scale national implementation.