Restoring the Great Basin Desert, U.S.A.: Integrating Science, Management, and People

The Great Basin Desert lies between the Sierra Nevada Mountains to the west and the Rocky Mountains to the east. Nearly 60% of the area’s deserts and mountains (roughly 30 million ha) are managed by the U. S. Department of Interior’s Bureau of Land Management. This area is characterized by low annual precipitation, diverse desert plant communities, and local economies that depend on the products (livestock grazing, recreation, mining, etc.) produced by these lands. The ecological and economic stability of the Great Basin is increasingly at risk due to the expansion of fire-prone invasive species and increase in wildfires. To stem this loss of productivity and diversity in the Great Basin, the BLM initiated the “Great Basin Restoration Initiative” in 1999 after nearly 0.7 million ha of the Great Basin burned in wildfires. The objective of the Great Basin Restoration Initiative is to restore plant community diversity and structure by improving resiliency to disturbance and resistance to invasive species over the long-term. To accomplish this objective, a strategic plan has been developed that emphasizes local participation and reliance on appropriate science to ensure that restoration is accomplished in an economical and ecologically appropriate manner. If restoration in the Great Basin is not successful, desertification and the associated loss of economic stability and ecological integrity will continue to threaten the sustainability of natural resources and people in the Great Basin.     

Monitoring dissolved copper concentrations in Chesapeake Bay,U.S.A.

Dissolved copper and selected water chemistry parameters were monitored for 11 months in Chesapeake Bay, U.S.A. Dissolved copper concentrations in four recreational marinas, a large harbor, two major river systems, and a heavily used shipping canal ranged from below detectable levels to 80 g L^-1 (\-X=11.7 g L^-1). Dissolved copper was detected >91% of the time at five locations. Lowest copper concentrations were found in Potomac River, Baltimore Harbor, Pier One Marina, and C & D Canal (\-X=6–10 g L^-1; slightly higher levels of dissolved copper were found in Choptank River (\-X=12 g L^-1). Highest levels of copper were detected in Port Annapolis, Hartge, and Piney Narrows Marinas (\-X=13–18 g L^-1), with the highest values observed in the study (70 and 80 g L^-1) found in two of these marinas. Copper in the three marinas with highest dissolved copper levels could have been toxic to some of the more sensitive aquatic species. Intensive study of one marina indicated that a likely source of dissolved copper was the recreational boats housed in the marina.     

Landscape ecosystem classification in the Cherokee National Forest,east Tennessee,U.S.A.

A landscape ecosystem classification is described for the 43 800 ha Foothills section (elevation 305 to 610 m) of the southern unit of the Cherokee National Forest. Vegetative cover, landform, and soils data were obtained from sixty 0.04 ha plots located in stands representing late successional stages. Vegetation data were grouped by dominant cover type utilizing agglomerative, hierarchical clustering and detrended correspondence analysis. Detrended canonical correspondence analysis (DCCA) and stepwise discriminant analysis (SDA) were used to identify patterns in species composition explained by environmental variables.Four community types were identified: (1) Tsuga canadensis-Acer saccharum-Fagus grandifolia-Fraxinus americana, (2) Tsuga canadensis-Rhododendron maximum, (3) Quercus prinus, and (4) Quercus prinus-Quercus coccinea-Acer rubrum. A recently developed Landform Index that quantifies slope type and degree of protection by adjacent land masses was identified through DCCA and SDA as the most important predictor of community types. The strength of the correlations between elevation and several soil thickness variables with DCCA axis 1 indicated that vegetation varies along an interpreted moisture gradient. No ecological meaning was attributed to the second axis.     

Production,respiration and net ecosystem metabolism in U.S. estuaries

Primary production, respiration, and net ecosystem metabolism (NEM) are useful indicators of ecosystem level trophic conditions within estuaries. In this study, dissolved oxygen data collected every half hour between January 1996 to December 1998 by the National Estuarine Research Reserve System Wide Monitoring Program were used to calculate primary production, respiration, and net ecosystem metabolism. Data from two sites at each of 14 Reserves were analyzed. On average, three quarters of the data available could be used to calculate metabolic rates. Data from two of the Reserves were used to evaluate the assumption of homogeneity of water masses moving past the oxygen sensor. Temperature was the single most important factor controlling metabolic rates at individual sites, although salinity was also important at about half the sites. On an annual basis, respiration exceeded gross primary production demonstrating that all but 4 of the 28 sites were heterotrophic.     

Aldehyde Concentrations in Ambient Air of Coastal Georgia, U.S.A.

Aldehydes are an airborne byproduct of many industrialprocesses, vehicle transportation, and emissions fromnumerous natural sources. To characterize aldehydeconcentrations in ambient air of the Savannah, Georgiaarea, air samples for 3 aldehydes (formaldehyde,acetaldehyde, and propionaldehyde) were collected atfive sites on a monthly basis over a 12-month periodfrom December of 1995 through November 1996. Four ofthe sites were in central Savannah and the fifth sitewas located in a rural area about 56 km south ofSavannah. During each 24-hr sampling episode, sampleswere collected in two 12-hr periods approximatingdaylight and nighttime hours, following U.S. EPAMethod TO-11. Formaldehyde concentrations ranged from0.17 to 6.80 g m^-3, acetaldehydeconcentrations ranged from 0.07 to7.60 g m^-3, and propionaldehyde levels rangedfrom 0.02 to 9.10 g m^-3. On average, thefour sites in Savannah had higher aldehydeconcentrations than the rural site (2.0 versus1.2 g m^-3 for formaldehyde, 2.3 versus1.7 g m^-3 for acetaldehyde, and 1.2 versus1.0 g m^-3 for propionaldehyde). The daytimeconcentrations for formaldehyde and acetaldehyde werehigher than the nighttime levels. The data from allthe sites were within published worldwide backgroundvalues for aldehydes.     

Background Mercury Concentrations in River Water in Maine, U.S.A.

Mercury concentrations in 58 rivers in Maine was measured to range from below detection up to 7.01 ng L^-1 and averaged 1.80±1.29 ng L^-1. The concentration gradient for mercury in rivers across the state was not uniform. Mercury strongly correlated with dissolved organic carbon (DOC) and aluminum, and less strongly with copper, lead, and zinc. Mercuryexhibited significant differences in correlations with chemical variables and local geology when partitioned by flow state (high or low). Mercury concentrations were greatest in rivers flowingacross either wacke-type bedrock at low metamorphic grade, or glacial-till deposits. Elevated concentrations of mercury formed a locus in northern Maine under both high and low-flow states while in southwestern Maine a locus formed only during high-flowstates. These regional differences were statistically significantwhen compared by geographical location. We suggest that there is a bedrock source of mercury in northeastern Maine that is dilutedduring periods of high runoff. The elevated concentrations detected under high-flow states, as noted in southwestern Maine, may reflect mercury released from storage in association withDOC during periods of high runoff. The association of mercury with flow state indicates that watershed processes and local geology can modulate the concentration of mercury in rivers.     

Status and Trends of Dissolved Oxygen in Corpus Christi Bay, Texas, U.S.A.

The purpose of this studywas to determine status and long-term trends of dissolved oxygen concentrations (DO) in Corpus Christi Bay, Texas, U.S.A. A 20-year record of randomized stations was used to determine the trend of surface water DO, salinity, and temperature over space and time. A 13-year record of two fixed stations was used to determine the temporal nutrient trends. A 10-year record of fixed stations in the southeastern region of Corpus Christi Bay was used to determine the status of disturbance caused by low DO in bottom waters. From 1982 to 2002, there was a significant decrease in surface water DO at a rate of 0.06 mg L⁻¹ yr⁻¹ and a significant increase in surface water temperature at a rate of 0.07°C yr⁻¹. The southeastern region of Corpus Christi Bay had the lowest average DO, and during July and August, DO are steadily declining at a rate of 0.09 mg L⁻¹ yr⁻¹. It is not likely that eutrophication is causing hypoxia, because freshwater inflow rates have significantly decreased since 1941 and nutrient levels have not changed from 1987 to 2000. Even though long-term trends indicate that average surface DO is decreasing, disturbance by hypoxia appears to be stable, but this may be due to just eight years of data. In fact, if the current trend continues, surface water DO will not meet exceptional aquatic life standards (≤5 mgL⁻¹) in 2032.     

Metals, Boron, and Selenium in Neosho Madtom Habitats in the Neosho River in Kansas, U.S.A.

In 1991 and 1992 we determined the levels of metals, arsenic, boron, and selenium in the Neosho River drainage in southeastern Kansas, the primary habitat for the threatened Neosho madtom (Noturus placidus). We evaluated concentrations in sediments, mussels (Quadrula pustulosa and Q. metanevra), and fish(Percina phoxocephala, Cyprinus carpio,and Ictiobus bubalus) from three sites on theNeosho River and one site on the Cottonwood River. We also evaluated contaminant concentrations in C. carpio composite samples collected by theKansas Department of Health and Environment (KDHE)at two additional locations on the Neosho River in1990–92. Sediments were contaminated by lead. Concentrations of selenium, boron, and most metalsin mussels were low to normal for biota. Arseniclevels in mussels and fish suggest low-levelcontamination of biota. Aluminum, barium, manganeseand strontium concentrations were much higher inmussels than in fish. Five fish composite sampleshad cadmium concentrations that indicate chronicdeleterious effects on biota. Lead concentrationsin six fish samples were elevated. Mercuryconcentrations in most large fish compositesexceeded concentration for protection of animalsthat might consume them. We believe that reductionsin cadmium, lead, and mercury contamination, inparticular, would benefit aquatic life in theriver.     

Environmental contaminants and productivity in an extinct heronry at Charleston Harbor,South Carolina,U.S.A., 1984

Our objectives were to collect information on contaminant levels and productivity of wading birds at the Drum Island heronry in Charleston Harbor, South Carolina, before diversion of the Cooper River took place in 1985. The diversion was expected to reduce water flow by 80% into the Harbor, thereby concentrating industrial effluents near the heronry with potentially harmful effects. Hatching success of white ibises (Eudocimus albus) in 1984 averaged 66% and 1.0 chick per nest survived to three weeks post-hatch. Fresh eggs collected from a sample of nests contained only background levels of DDT, DDE, and Dieldrin; no PCBs, diphenyl ethers, or styrenes were detected. Pesticide residues in eggs were not correlated (P>0.05) with productivity in corresponding nests. Heavy metals and selenium in tissues of wading bird chicks were also representative of background levels. Follow-up studies after the diversion of the Cooper River were not feasible because the heronry was abandoned beginning in 1985. However, our baseline results will be useful in determining potential contaminant effects due to diversion of the Cooper River should wading birds return to Drum Island in the future.     

Ambient elemental, reactive gaseous, and particle-bound mercury concentrations in New Jersey, U.S.: measurements and associations with wind direction

Two and a half years of data of ambient concentrations of elemental mercury (Hg(0)), reactive gaseous mercury (RGM), and particle-bound mercury (Hg(p)) were collected at measurement sites at Elizabeth, New Jersey and New Brunswick, New Jersey with Tekran sampling units. The data were processed, summarized, and analyzed from a variety of perspectives. Data quality control and quality assurance procedures are described. Wind direction and wind speed data for each of the sites were also collected. Significant temporal variations in concentrations of all three species were observed. Some significant directional variations were also seen. The sporadic nature of many of the temporal variations is consistent with and could reflect highly variable emissions patterns from anthropogenic mercury sources. Overall mean concentrations of all species were determined. These were, for Hg(0), Hg(p), and RGM respectively; 2.25 +/- 0.04 nanograms per cubic meter (ng/m(3)), 8.21 +/- 0.39 picograms per cubic meter (pg/m(3)), and 8.93 +/- 0.31 pg/m(3) (arithmetic means and 95% confidence intervals) at Elizabeth, and 2.15 +/- 0.02 ng/m(3), 10.73 +/- 0.45 pg/m(3), and 6.04 +/- 0.30 pg/m(3) at New Brunswick. Mean concentrations were determined for 16 different sectors representing wind directions. The impact of one known large source is suggested by these data. Reasons for some directional variations are not apparent and suggest a need for further investigation.     

A Provisional Fish Index of Biotic Integrity for Assessing Ouachita Mountains Streams in Arkansas, U.S.A.

Multimetric indices are often used to monitor aquatic-resource conditions. We used existing fish-collection data from streams to develop an Index of Biotic Integrity (IBI), which is a multimetric index, for the Ouachita Mountains ecoregion in Arkansas, U.S.A. Each fish-collection site was categorized as reference or non-reference. We examined 62 candidate IBI metrics, and selected 12 non-redundant metrics that differentiated best between reference and non-reference sites. The selected metrics were: Percent (of individuals) as Black Bass; Percent as Benthic Feeders; Percent as Centrarchids; Percent as Cyprinids; Percent as Ictalurids; Percent as Mineral, Site-Prep Spawners; Percent as Mineral, Site-Prep, Parental-Care Spawners; Percent as Simple, Mineral Substrate Spawners; Percent as Miscellaneous, Site-Prep, Parental-Care Spawners; Total Number of Centrarchid Species; Total Number of Arkansas Department of Environmental Quality (ADEQ) Ouachita Mountains Indicator Species; and Total Number of ADEQ Ouachita Mountains Key Species. We standardized each metric to score from 0 to 10 by using linear equations and threshold limits. Some selected IBI metrics had their scoring criteria adjusted to account for watershed size (i.e., stream size). We standardized the IBI to score from 0 to 100. In addition, we determined that our Percent as Black Bass and Percent as Benthic Feeders metrics contributed most to IBI scores in reference conditions, but their contributions decreased with decreasing stream conditions. Reproductive metrics contributed most in degraded stream conditions. Furthermore, we identified relations between IBI metrics and water-quality and land-use variables; some relations were counterintuitive. Unexpected relations may be random observations explained by limited ranges of land-use and water-quality variables. When select water-quality and land-use variables were included in a principal component analysis, a composite Land Use Intensity variable explained most of the model variance. Although the IBI has not been independently validated, the PCA, as well as other superficial analyses, indicated that the IBI should be able to differentiate stream conditions.     

Ozone Exposures and Implications for Vegetation in Rural Areas of the Central Appalachian Mountains, U.S.A.

The United States is making the transition from the 1979 1 hr maximum ozone standard to the newly adopted 8 hr ozone standard (3 yr average of the 4th highest maximum 8 hr ozone concentration). Consequently, we analyzed and compared ozone concentrations under both standards from a variety of monitoring sites throughout the central Appalachian region of Kentucky (KY), West Virginia (WV), and Virginia (VA). Data from 1988-1999 were used to determine how ozone exposure between the two metrics compared for remote sites. Most sites exceeded the 1 hr standard in 1988-1990 due to the 3 yr averaging and multiple high ozone concentrations that occurred over the region in 1988. All sites were in compliance with the 1 hr standard every year after 1991. It was much more common for the ozone exposure to exceed the 8 hr standard, particularly from 1997-1999. Many sites showed exceedences beginning in 1995; Big Meadows (VA) exceeded the 8 hr standard all years except 1994 and 1996. Response of vegetation to ozone in these areas was determined using the combination of W126 values (sigmoidally weighted exposure index), the number of hours that average concentrations > or = 0.10 ppm (N100), and the presence of moderate or more extreme droughts. In general, W126 and N100 values suggested that negative vegetation growth responses over most of the 12 yr would have been minimal for most sites, even for those exceeding ozone standards. Drought-induced stomatal closures would have overridden more extreme negative growth responses at all but the Big Meadows site in 1988.     

Biomagnification factors (fish to Osprey eggs from Willamette River,Oregon, U.S.A.) for PCDDs,PCDFs, PCBs and OC pesticides

A migratory population of 78 pairs of Osprey (Pandion haliaetus) nesting along the Willamette River in westernOregon was studied in 1993. The study was designed to determinecontaminant concentrations in eggs, contaminant concentrationsin fish species predominant in the Ospreys diet, andBiomagnification Factors (BMFs) of contaminants from fish specieseaten to Osprey eggs. Ten Osprey eggs and 25 composite samplesof fish (3 species) were used to evaluate organochlorine (OC)pesticides, polychlorinated biphenyls (PCBs), polychlorinateddibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans(PCDFs). Mercury was also analyzed in fish. Geometric meanresidues in Osprey eggs were judged low, e.g., DDE 2.3 g g^-1 wet weight (ww), PCBs 0.69 g g^-1, 2,3,7,8-TCDD 2.3 ng kg^-1, and generally well below known threshold values for adverse effects on productivity, and the population was increasing. Osprey egg residue data presentedby River Mile (RM) are discussed, e.g., higher PCDDs were generally found immediately downstream of paper mills and eggsfrom the Willamette River had significantly elevated PCBs and PCDDs compared to reference eggs collected nearby in the CascadeMountains. Prey remains at nest sites indicated that the Largescale Sucker (Catostomus macrocheilus) and NorthernPikeminnow (Ptychocheilus oregonensis) accounted for an estimated 90.1% of the biomass in the Osprey diet, and composite samples of these two species were collected from different sampling sites throughout the study area for contaminant analyses. With the large percentage of the fishbiomass in the Osprey diet sampled for contaminants (and fisheaten by Ospreys similar in size to those chemically analyzed),and fish contaminant concentrations weighted by biomass intake, a mean BMF was estimated from fish to Osprey eggs for the largeseries of contaminants. BMFs ranged from no biomagnification(0.42) for 2,3,7,8-TCDF to 174 for OCDD. Our findings for themigratory Osprey were compared to BMFs for the resident HerringGull (Larus argentatus), and differences are discussed. Webelieve a BMF approach provides some basic understanding ofrelationships between contaminant burdens in prey species offish-eating birds and contaminants incorporated into their eggs,and may prove useful in understanding sources of contaminants inmigratory species although additional studies are needed.     

Distributions and sources of polycyclic aromatic hydrocarbons in surface sediments from the Cross River estuary,S.E. Niger Delta,Nigeria

Polycyclic aromatic hydrocarbon (PAH) analyses of surface sediments from the Cross River estuary by gas chromatography–mass spectrometry indicated natural diagenetically derived PAHs in the upper estuary, with minor and variable amounts of petrogenic and combustion-derived PAHs from human activities (lower estuary). The occurrence of significant amounts of perylene (average 23% of all PAHs) with the diagenetic natural PAHs in the middle estuary bordered by mangrove forests supports its origin from terrestrial organic matter. The natural PAHs represent the highest percentage (average 76%) of the total PAHs in this tropical environment. The traditional geochemical parameters, including the petrogenic PAHs, confirmed trace petroleum contamination in the estuary. Specific PAH ratios such as Fl/Py and Fl/(Fl+Py) also support this source contribution.     

Concentrations and profiles of polychlorinated biphenyls, -dibenzo-p-dioxins and -dibenzofurans in livers of mink from South Carolina and Louisiana,U.S.A

In South Carolina, U.S.A., mink have been reintroduced from two apparently healthy populations to areas where populations haveexisted in the past but have been extirpated. High mortality wasobserved during transport of mink from the source populations. Inorder to elucidate the potential effects of dioxin-like compoundson the survival and reproduction of mink, concentrations of totalpolychlorinated biphenyls (PCBs), p,p-DDE, dioxin-likePCBs, polychlorinated dibenzo-p-dioxins (PCDDs), anddibenzofurans (PCDFs) were measured in livers of mink collectedfrom the source populations in South Carolina and Louisiana. Concentrations of total 2,3,7,8-tetrachlorodibenzo-p-dioxinequivalents (TEQs) for the South Carolina and Louisiana mink were21 and 14 pg g^-1, wet wt., respectively. PCB and TEQ concentrations were close to the threshold values that can, under laboratory conditions, elicit toxic effects in ranchmink. Therefore, any additional exposures of these populations toTEQs might adversely affect their populations.     

Water quality assessment through hydrodynamics and transport simulation in the S. Gilla lagoon, Italy

The paper describes the study of the hydrodynamic and transport features of the S. Gilla lagoon in Sardinia, Italy. The study, aimed at assessing the environmental quality of the water body, involved extensive use of numerical models based on the shallow water equations, thus enabling to simulate a number of different situations of practical interest. Based on field data, six meteorological and hydrologic patterns were recognised which were assumed as representative of the various conditions occurring in the four seasons. Typical winter conditions proved effective for the water refreshment, while the other seasonal patterns induced a stronger internal mixing. Thus, unfavourable salinity distributions with respect to the fish farm activities, which are carried out in the water body, were obtained with the winter pattern, whereas, on the other hand, a higher dilution of pollutants discharged by the river inflows was achieved. In general, between dominant winds, southeast winds proved more effective in forcing internal mixing than northwest winds. Two flood events with quite different return periods were also simulated, in order to estimate the extent of the inundated areas and the salinity depletion. The consequent salinity recovery was simulated both in natural conditions and with the discharge of salt sea water into the lagoon to accelerate the salinity re‐equilibrium. This revised version was published online in August 2006 with corrections to the Cover Date.     

Sediment Quality of Estuaries in the Southeastern U.S.

A study was conducted to assess the condition of estuaries in the EMAP Carolinian Province (Cape Henry, VA - St. Lucie Inlet, FL). Synoptic measures of sediment contamination, toxicity, and macroinfaunal condition were made at 82 and 86 stations in 1994 and 1995, respectively, in accordance with a probabilistic sampling design. These data were used to estimate percentages of degraded vs. undegraded estuarine area from the perspective of sediment quality. Each year a sizable portion of the province (36% in 1994, 51 % in 1995) showed some evidence of either degraded benthic assemblages, contaminated sediments in excess of bioeffect guidelines, or significant sediment toxicity (based on Ampelisca abdita and Microtox® assays). However, co-occurrences of a degraded benthos and adverse exposure conditions (sediment contamination and/or toxicity) were much less extensive – 17% of the province in 1994 and 25% in 1995. Each year only four sites, representing 5% of the province in 1994 and 8% in 1995, had degraded infauna accompanied by both sediment contamination and toxicity, suggesting that strong contaminant-induced effects on the benthos (based on such combined weight-of-evidence) were limited to a fairly small percentage of estuarine area province-wide. PCBs and pesticides (lindane, dieldrin, DDT and derivatives) were the most dominant contaminants over the two-year period. The broad-scale sampling design of EMAP was not intended to support detailed characterizations of potential pollutant impacts within individual estuaries. Thus, some estuaries classified as undegraded may include additional degraded portions outside the immediate vicinity of randomly sampled sites. Such localized impacts (not accounted for in the above estimates) were detected in this study at additional nonrandom supplemental sites near potential contaminant sources.     

Impervious Surface Area as a Predictor of the Effects of Urbanization on Stream Insect Communities in Maine, U.S.A.

The influence of urbanization on stream insect communities was determined by comparing physical, chemical, and biological characteristics of streams draining 20 catchments with varyinglevels of urban land-cover in Maine (U.S.A). Percent total impervious surface area (PTIA), which was used to quantify urbanland-use, ranged from 1–31% among the study catchments.Taxonomic richness of stream insect communities showed an abruptdecline as PTIA increased above 6%. Streams draining catchmentswith PTIA < 6% had the highest levels of both total insect and EPT (Ephemeroptera + Plecoptera + Trichoptera) taxonomic richness. These streams contained insect communities with a totalrichness averaging 33 taxa in fall and 31 taxa in spring; EPT richness ranged from an average of 15 taxa in fall and 13 taxa inspring. In contrast, none of the streams draining catchments with6–27% PTIA had a total richness > 18 taxa or an EPT richness> 6 taxa. Insect communities in streams with PTIA > 6% were characterized by the absence of pollution-intolerant taxa. The distribution of more pollution-tolerant taxa (e.g.Acerpenna (Ephemeroptera); Paracapnia, Allocapnia (Plecoptera); Optioservus, Stenelmis (Coleoptera); Hydropsyche, Cheumatopsyche (Trichoptera)), however, showed little relation to PTIA. In contrast to the apparent threshold relationship between PTIA and insect taxonomic richness, both habitat qualityand water quality tended to decline as linear functions of PTIA.Our results indicate that, in Maine, an abrupt change in stream insect community structure occurs at a PTIA above a threshold ofapproximately 6% of total catchment area. The measurement of PTIA may provide a valuable tool for predicting thresholds for adverse effects of urbanization on the health of headwater streams in Maine.