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USGS1983

Reconnaissance of surface-water resources in the Kobuk River basin, Alaska, 1979-80

Surface water data were collected at selected sites in the Kobuk River Basin in northwest Alaska in August 1979 and April 1980. In August 1979, frequent heavy rains caused abnormally high flows in the basin; unit runoff values, computed from discharge measurements at 25 sites, ranged from 0.08 to 12.2 cu ft/sec/sq mi. Mean unit runoff for August computed from 13 years of record at a stream gaging station on the Kobuk River ranged from 1 to 3 cu ft/sec/sq mi. Unit runoff computed from discharge measurements made at eight sites in April 1980 ranged from 0 to 0.30 cubic feet per second per square mile. These values are in reasonable agreement with those derived from the record at the gaging station. High-water marks of maximum evident floods and evidence of ice-affected flooding were found at near bankfull stages at 17 sites on the Kobuk River and its tributaries. Computed unit runoff for the maximum evident floods generally decreases with increasing drainage area. Unit runoff ranges from about 50 to 75 cu ft/sec/sq mi for drainage areas < 1,000 sq mi to < 25 cu ft/sec/sq mi for larger areas. Field determinations were made of water temperature, pH, alkalinity, dissolved-oxygen concentration, and specific conductance, and discharge was measured at about 40 stream sites and one spring. Water samples for laboratory analysis of dissolved inorganic constituents and biological samples were collected in August 1979. Water quality data indicate that the surface waters would be acceptable for most uses; they are a calcium bicarbonate type having dissolved-solids concentrations between 50 and 140 milligm/liter. The pristine nature of the waters is also indicated by the overall diversity and composition of its benthic invertebrate community. A more highly mineralized (about 550 milligm/liter dissolved solids) sodium bicarbonate water flows from Reed River Hot Spring. (USGS)

Water-Resources Investigations Report↗

USGS2005

An evaluation of effects of groundwater exchange on nearshore habitats and water quality of western Lake Erie

Historically, the high potentiometric surface of groundwater in the Silurian/Devonian carbonate aquifer in Monroe County, MI resulted in discharge of highly mineralized, SO 4 -rich groundwater to the Lake Erie shoreline near both Erie State Game Area (ESGA) and Pointe Mouillee State Game Area (PMSGA). Recently, regional groundwater levels near PMSGA have been drawn down as much as 45 m below lake level in apparent response to quarry dewatering. From August to November of 2003, we conducted preliminary studies of groundwater flow dynamics and chemistry, shallow lake water chemistry, and fish and invertebrate communities at both sites. Consistent with regional observations, groundwater flow direction in the nearshore at ESGA was upward, or toward Lake Erie, and shallow nearshore groundwater chemistry was influenced by regional groundwater chemistry. In contrast, at PMSGA, the groundwater flow potential was downward and lake water, influenced by quarry discharge seeping downward into nearshore sediments, produced a different lake and shallow groundwater chemistry than at ESGA. Although the invertebrate and young fish community was similar at the two sites, taxonomic groups tolerant of degraded water quality were more prevalent at PMSGA. Sensitive taxa were more prevalent at ESGA. We propose a conceptual model, based on well-described models of groundwater/seawater interaction along coastal margins, to describe the interconnection among geologic, hydrologic, chemical, and biological processes in the different nearshore habitats of Lake Erie, and we identify processes that warrant further detailed study in the Great Lakes.

Lake Erie↗

USGS2025

Arsenic accumulation in Sonora Mud Turtles (Kinosternon sonoriense) in an unusual freshwater food web

Montezuma Well is an unusual fishless, spring-fed, desert wetland in central Arizona. Water in the wetland is naturally enriched with > 100 µg/l dissolved geogenic arsenic (As) and supports a simple aquatic food web dominated by a small number of endemic invertebrate species that achieve high abundances. Previous studies of As among various environmental compartments and organisms in Montezuma Well did not include omnivorous Sonora Mud turtles ( Kinosternon sonoriense ) despite their potential importance in the As cycle by virtue of their substantial biomass and role as top predators. We measured As concentrations in water, sediment, and organisms (macrophytes, amphipods, insects, leeches, and turtles) representing a range of trophic levels in order to document the importance of turtles at the apex of the Montezuma Well food web and in the As cycle. Concentrations of As in turtles varied according to tissue type. The greatest values (up to 26.77 mg/kg dry weight) were in the scutes of 1 of our oldest turtles (31.5 yrs). These elevated concentrations may be due to the affinity of As to react with sulfur in the keratin of scutes, and therefore might reflect duration of exposure in long-lived turtles. Although As concentrations generally tend to decrease when moving up to higher trophic levels in a food web, our results were different. Relatively elevated concentrations reported in sediments by us and a previous study declined in plant samples as expected. Amphipod concentrations increased but then decreased again in 3 of their invertebrate predators. Arsenic concentrations in endemic leeches were extremely elevated with a mean value of 72.2 mg/kg. The mean concentration of As in turtles was 7.08 mg/kg across tissue types and was greater than the plants or invertebrates they eat, with the notable exception of leeches, which have been proposed to be part of their diet.

Arizona↗

USGS1981

Selected biological characteristics of streams in the southeastern Uinta Basin, Utah and Colorado

Biological sampling was carried out during 1976-78 in five streams in the southeastern Uinta Basin, Utah and Colorado, in order to provide baseline water-quality data for an area of potential oil-shale development. The biological activity in the streams sampled generally is limited by physical factors more so than by chemical constituents and plant nutrients. Characteristics of streamflow, such as high turbidity, fluctuating water levels, and moderate to high salinity, limit production of flora and fauna biomass. Samples were collected for the determination of bacterial and periphyton concentrations and benthic-invertebrate communities. Bacterial concentrations were generally small, with some fecal contamination, primarily from livestock and wildlife. Members of the order Chlorophyta (green algae) were the major periphytic algae present in three of the streams sampled. Bitter Creek was dominated by members of the order Cyanphyta (blue-green algae), and pennate diatoms were the predominant algae in Willow Creek. The benthic-invertebrate communities generally reflect a nonpolluted environment. Shannon-Weiner diversity indices ranged from 1.14 to 3.08.

Colorado, Utah↗

USGS1996

Summary of biological investigations relating to water quality in the Western Lake Michigan Drainages, Wisconsin and Michigan

This report summarizes aquatic biological studies relevant to water-quality assessment that have been done in the Western Lake Michigan Drainages from 1891 to 1996. The objective of the summary was to compile sources of biological data for the U.S. Geological Survey's National Water-Quality Assessment Program. The studies are divided into four categories: (1) populations and community structure of aquatic biota, (2) health of aquatic biota, (3) chemical concentrations in tissues of aquatic biota, and (4) toxicity tests by use of aquatic biota. Studies are further categorized by subbasin, spatial scale (regional or local), types of biota, and, if applicable, effect or contaminant investigated. For the purposes of this report, the study area is divided into five subbasins. The subbasins, from north to south, are (1) the Ford/Escanaba Subbasin in Michigan's Upper Peninsula, and in Wisconsin, (2) the Menominee/ Oconto/Peshtigo Subbasin, (3) the Fox/Wolf Subbasin, (4) the Sheboygan/Manitowoc/Twin Subbasin, and (5) the Milwaukee Subbasin. Most biological studies related to waterquality conditions in the Western Lake Michigan Drainages have focused on populations and community structure of aquatic biota. Chemical concentrations in tissues of aquatic biota have been the next most common area of research. Our review suggests a paucity of data related to the health of all types of aquatic biota, especially amphibians, invertebrates, and reptiles; toxicity studies also were relatively uncommon. Overall, organisms primarily studied have been fish and invertebrates, although birds are most frequently examined in studies of organism health. The Fox/ Wolf Subbasin has been the focus of many more studies than the other subbasins, most likely because of the greater extent and severity of known water-quality problems in the Lower Fox River/Green Bay area over the past several decades and because it is the largest subbasin. Studies in the other subbasins are needed to adequately assess the water quality of these areas.

Michigan, Wisconsin↗

USGS1976

Limnological data for the major streams in Chester County, Pennsylvania

Limnological data on major streams in Chester County, Pennsylvania are tabulated to provide a base line as to the present stream conditions. As land-use patterns change and further urbanization takes place, it is anticipated that these data will serve as a basis for comparison of conditions in the future. The 13 basins encompass a total drainage area of 1,812 km2 (697 mi2) of the 1,976 km2 (760 mi2) within Chester County. Four of the streams are tributaries to the Schuylkill River and include Pickering, Stony Run, Pigeon, and French Creek. Tributaries to the Delaware River include Darby, Crum, Ridley, Chester, Red Clay, and White Clay Creeks. The Elk Creeks flow into the Chesapeake Bay. The Brandywine is a tributary to the Christiana River, itself a tributary to the Delaware. The Octoraro Creek is a tributary to the Susquehanna River. Chester County, which is located in the Piedmont area of Pennsylvania, is undergoing rapid transition from a rural to suburban condition as the population increases. This basic-data report contains the chemical, physical, and biological information collected for the period fall 1969 through fall 1974. The network of 50 stations is shown in figure 1, which is followed by a listing (table 1) of station numbers and a brief description of station locations. Table 2 shows the physical, chemical, and bacteriological data collected by station and date. Table 3 shows the benthic invertebrate data collected by station and date.

Pennsylvania↗

USGS2007

Oceanography of Glacier Bay, Alaska: Implications for biological patterns in a glacial fjord estuary

Alaska, U.S.A, is one of the few remaining locations in the world that has fjords that contain temperate idewater glaciers. Studying such estuarine systems provides vital information on how deglaciation affects oceanographic onditions of fjords and surrounding coastal waters. The oceanographic system of Glacier Bay, Alaska, is of particular interest ue to the rapid deglaciation of the Bay and the resulting changes in the estuarine environment, the relatively high oncentrations of marine mammals, seabirds, fishes, and invertebrates, and the Bay’s status as a national park, where ommercial fisheries are being phased out. We describe the first comprehensive broad-scale analysis of physical and iological oceanographic conditions within Glacier Bay based on CTD measurements at 24 stations from 1993 to 2002. easonal patterns of near-surface salinity, temperature, stratification, turbidity, and euphotic depth suggest that freshwater nput was highest in summer, emphasizing the critical role of glacier and snowmelt to this system. Strong and persistent tratification of surface waters driven by freshwater input occurred from spring through fall. After accounting for seasonal nd spatial variation, several of the external physical factors (i.e., air temperature, precipitation, day length) explained a large mount of variation in the physical properties of the surface waters. Spatial patterns of phytoplankton biomass varied hroughout the year and were related to stratification levels, euphotic depth, and day length. We observed hydrographic atterns indicative of strong competing forces influencing water column stability within Glacier Bay: high levels of freshwater ischarge promoted stratification in the upper fjord, while strong tidal currents over the Bay’s shallow entrance sill enhanced ertical mixing. Where these two processes met in the central deep basins there were optimal conditions of intermediate tratification, higher light levels, and potential nutrient renewal. These conditions were associated with high and sustained hlorophyll a levels observed from spring through fall in these zones of the Bay and provide a framework for understanding he abundance patterns of higher trophic levels within this estuarine system.

Estuaries and Coasts↗

USGS1981

Aquatic biology of the Redwood Creek and Mill Creek drainage basins, Redwood National Park, Humboldt and Del Norte counties, California

A 2-year study of the aquatic biota in the Redwood Creek and Mill Creek drainage basins of Redwood National Park indicated that the aquatic productivity is low. Densities of coliform bacteria were low except in Prairie Creek, a tributary to Redwood Creek, where a State park, county fish hatchery, grazing land, lumber mill, and scattered residential areas are potential sources of fecal coliform bacteria. Benthic invertebrate data indicated a diverse fauna which varied considerably between streams and among stream sections. Noteworthy findings include: (1) benthic invertebrates rapidly recolonized the streambed following a major storm, and (2) man-caused disruption or sedimentation of the streambed during low flow can result in drastic reductions of the benthic invertebrate community. Seven species of fish representing species typically found in northern California coastal streams were captured during the study. Nonparametric statistical tests indicate that condition factors of steelhead trout were significantly larger at sampling stations with more insolation, regardless of drainage basin land-use history. Periphyton and phytoplankton communities were diverse, variable in numbers, and dominated by diatoms. Seston concentrations were extremely variable between stations and at each station sampled. The seston is influenced seasonally by aquatic productivity at each station and amount of allochthonous material from the terrestrial ecosystem. Time-series analysis of some seston data indicated larger and sharper peak concentrations being flushed from the logged drainage basin than from the control drainage basin. (USGS)

California↗

USGS2004

Reconnaissance of chemical and biological quality in the Owyhee River from the Oregon State line to the Owyhee Reservoir, Oregon, 2001–02

The Owyhee River drains an extremely rugged and sparsely populated landscape in northern Nevada, southwestern Idaho, and eastern Oregon. Most of the segment between the Oregon State line and Lake Owyhee is part of the National Wild and Scenic Rivers System, and few water-quality data exist for evaluating environmental impacts. As a result, the U.S. Geological Survey, in cooperation with the Bureau of Land Management, assessed this river segment to characterize chemical and biological quality of the river, identify where designated beneficial uses are met and where changes in stream quality occur, and provide data needed to address activities related to environmental impact assessments and Total Maximum Daily Loads. Water-quality issues identified at one or more sites were water temperature, suspended sediment, dissolved oxygen, pH, nutrients, trace elements, fecal bacteria, benthic invertebrate communities, and periphyton communities. Generally, summer water temperatures routinely exceeded Oregon's maximum 7-day average criteria of 17.8 degrees Celsius. The presence of few coldwater taxa in benthic invertebrate communities supports this observation. Suspended-sediment concentrations during summer base flow were less than 10 milligrams per liter (mg/L). Dissolved solids concentrations ranged from 46 to 222 mg/L, were highest during base flow, and tended to increase in a downstream direction. Chemical compositions of water samples indicated that large proportions of upland-derived water extend to the lower reaches of the study area during spring runoff. Dissolved fluoride and arsenic concentrations were highest during base flow and may be a result of geothermal springs discharging to the river. No dissolved selenium was detected. Upstream from the Rome area, spring runoff concentrations of suspended sediment ranged from 0 to 52 mg/L, and all except at the Three Forks site were typically below 20 mg/L. Stream-bottom materials from the North Fork Owyhee River, an area with no mines, were enriched with nine trace elements, which indicates that this basin may be a natural source of these elements. Near Rome, the part of the study area not included in the National Wild and Scenic Rivers System, land-use impacts resulted in elevated populations of Escherichia coli bacteria ( E. coli ) during base flow and elevated concentrations of nitrogen and phosphorus during spring runoff. Sites in this area had the highest numbers of benthic invertebrates; the fewest Ephemeroptera, Plecoptera, and Trichoptera taxa; and the highest Hilsenhoff Biotic Index scores. These results suggest degraded stream quality. Periphyton communities at sites in this area approached nuisance levels and could cause significant dissolved oxygen depletions and pH values that exceed Oregon's recommended criteria. Stream-bottom materials from Jordan Creek were enriched with mercury and manganese, which probably were ultimately caused by past mining in that basin. Below Crooked Creek, elevated suspended sediment concentrations (142 mg/L), phosphorus concentrations (0.23 mg/L), and E. coli populations (370 most probable number per 100 milliliters) during the largest spring runoff event could be the result of inputs at the lower end of Jordan Valley and (or) inputs from Crooked Creek. The New Zealand Mud Snail, a highly competitive gastropod introduced to the Snake River in the 1980s, was collected just downstream from the Crooked Creek confluence.

Idaho;Nevada;Oregon↗

USGS2019

Flow alteration-ecology relationships in Ozark Highland streams: Consequences for fish, crayfish and macroinvertebrate assemblages

We examined flow alteration-ecology relationships in benthic macroinvertebrate , fish, and crayfish assemblages in Ozark Highland streams, USA, over two years with contrasting environmental conditions, a drought year (2012) and a flood year (2013). We hypothesized that: 1) there would be temporal variation in flow alteration-ecology relationships between the two years, 2) flow alteration-ecology relationships would be stronger during the drought year vs the flood year, and 3) fish assemblages would show the strongest relationships with flow alteration. We used a quantitative richest-targeted habitat (RTH) method and a qualitative multi-habitat (QMH) method to collect macroinvertebrates at 16 USGS gaged sites during both years. We used backpack electrofishing to sample fish and crayfish at 17 sites in 2012 and 11 sites in 2013. We used redundancy analysis to relate biological response metrics, including richness, diversity, density, and community-based metrics, to flow alteration. We found temporal variation in flow alteration-ecology relationships for all taxa, and that relationships differed greatly between assemblages. We found relationships were stronger for macroinvertebrates during the drought year but not for other assemblages, and that fish assemblage relationships were not stronger than the invertebrate taxa. Magnitude of average flow, frequency of high flow, magnitude of high flow, and duration of high flow were the most important categories of flow alteration metrics across taxa. Alteration of high and average flows was more important than alteration of low flows. Of 32 important flow alteration metrics across years and assemblages, 19 were significantly altered relative to expected values. Ecological responses differed substantially between drought and flood years, and this is likely to be exacerbated with predicted climate change scenarios. Differences in flow alteration-ecology relationships among taxonomic groups and temporal variation in relationships illustrate that a complex suite of variables should be considered for effective conservation of stream communities related to flow alteration.

Arkansas, Missouri, Oklahoma↗

USGS2010

Invasion and production of New Zealand mud snails in the Colorado River, Glen Canyon

Species invasions are often associated with large-scale human alteration of ecosystems. One classic example is the increasing dominance of non-native taxa below and above dams on large rivers. These dams substantially alter the physical template of river ecosystems, and exotic taxa often proliferate with potentially large impacts on coexisting taxa and ecosystem processes. Here we document the invasion of New Zealand mud snails ( Potamopyrgus antipodarum ) in the Colorado River directly below Lake Powell in Glen Canyon, Arizona, USA. We also quantified the magnitude and variability in growth and secondary production of P. antipodarum during 2006–2007 to gain a functional measure of their role in the ecosystem. Snails were first detected in Glen Canyon in 1995, and have since become a dominant component of the invertebrate fauna. Throughout the invasion of P. antipodarum , biomass of other dominant taxa was variable and did not appear to be positively or negatively influenced by the presence of P. antipodarum . Specific growth rates of P. antipodarum were moderate (0.001–0.030 day −1 ) and strongly related to body size. Mean annual habitat-weighted biomass and production were relatively high (biomass: 4.4 g/m 2 ; secondary production: 13.3 g m −2 year −1 ) and similar among habitats. Mean monthly biomass and daily secondary production were much more variable, with highest values occurring in autumn. We show that invasion of a productive aquatic consumer to a highly disturbed river ecosystem had little detectable influence on the biomass of other invertebrate taxa. However, additional research will be necessary to fully understand and predict effects of P. antipodarum on coexisting taxa.

Arizona↗

USGS2006

Impacts of marsh management on coastal-marsh bird habitats

The effects of habitat-management practices in coastal marshes have been poorly evaluated. We summarize the extant literature concerning whether these manipulations achieve their goals and the effects of these manipulations on target (i.e., waterfowl and waterfowl food plants) and non-target organisms (particularly coastal-marsh endemics). Although we focus on the effects of marsh management on birds, we also summarize the scant literature concerning the impacts of marsh manipulations on wildlife such as small mammals and invertebrates. We address three common forms of anthropogenic marsh disturbance: prescribed fire, structural marsh management, and open-marsh water management. We also address marsh perturbations by native and introduced vertebrates.

Studies in Avian Biology↗

USGS2007

Nutrient and biological conditions of selected small streams in the Edwards Plateau, central Texas, 2005-06, and implications for development of nutrient criteria

During the summers of 2005 and 2006 the U.S. Geological Survey, in cooperation with the Texas Commission on Environmental Quality, evaluated nutrient and biological conditions in small streams in parts of the Edwards Plateau of Central Texas. Land-cover analysis was used to select 15 small streams that represented a gradient of conditions with the potential to affect nutrient concentrations across the study area, which comprises two of four subregions of the Edwards Plateau ecoregion. All 15 streams were sampled for water properties, nutrients, algae, benthic invertebrates, and fish in summer 2005, and eight streams were resampled in summer 2006. Streams that did not receive wastewater effluent had relatively low nutrient concentrations and were classified as oligotrophic; streams receiving wastewater effluent had relatively high nutrient concentrations and were classified as eutrophic. Nutrient concentrations measured in the least-disturbed streams closely matched the U.S. Environmental Protection Agency nutrient criteria recommendations based on estimated reference concentrations. Nitrogen/phosphorus ratios indicated streams not affected by wastewater effluent might be limited by phosphorus concentrations. Algal indicators of nutrient condition were closely related to dissolved nitrogen concentrations and streamflow conditions. Ambient dissolved nitrogen concentrations (nitrite plus nitrate) were positively correlated with benthic algal chlorophyll-a concentrations. The correlation of benthic algal chlorophyll-a with instantaneous nitrite plus nitrate load was stronger than correlations with ambient nutrients. Increased nutrient concentrations were associated with increased macroalgae cover, wider diel dissolved oxygen ranges, and reduced diel dissolved oxygen minimums. Benthic invertebrate aquatic life use scores generally were classified as High to Exceptional in study streams despite the influence of urbanization or wastewater effluent. Reductions in aquatic life use scores appeared to be related to extremely low flow conditions and the loss of riffle habitats. Benthic invertebrate aquatic life use scores and several of the metrics used to compute composite aquatic life use scores tended to increase with increasing total nitrogen concentrations. Fish community aquatic life use scores generally were classified as High or Exceptional with the exception of a few samples collected from streams receiving wastewater effluent that were classified as Intermediate. Fish community aquatic life use scores and several fish community metrics were positively correlated with nutrient concentrations and macroalgae cover. The majority of the positive correlations among nutrient concentrations, macroalgae cover, and fish metrics were strongly influenced by relatively high nutrient concentrations. Both benthic and planktonic chlorophyll-a measures were related to nutrients, but this study indicates that benthic chlorophyll-a was the better choice for monitoring nutrient enrichment because (1) the relation between benthic chlorophyll-a and nutrients was stronger, and (2) a strong relation between benthic chlorophyll-a and nutrients persisted after removal of the sites influenced by wastewater effluent, which indicates superior ability of benthic chlorophyll-a to discriminate between conditions at lower nutrient concentrations. The transect-based algal abundance estimate technique is a useful tool for identifying eutrophic conditions, assessing nuisance algal growth, and making broad comparisons among sites, but it appears to lack the fine resolution to identify lesser degrees of nutrient enrichment. Several individual benthic invertebrate and fish metrics were correlated with nutrient conditions, but correlations were generally positive and the reverse of what would be expected when nutrient enrichment causes a proliferation of algal growth and stream degradation. However, the benthic invertebrate functional feeding group metrics showed some

Scientific Investigations Report↗

USGS2015

Evaluating the piscicide rotenone as an option for eradication of invasive Mozambique tilapia in a Hawaiian brackish-water wetland complex

Mozambique tilapia Oreochromis mossambicus were recently discovered in ‘Aimakapā Fishpond, a 12-hectare brackish-water wetland complex in Kaloko-Honokōhau National Historical Park, on the Island of Hawai’i. As a possible eradication method, we evaluated rotenone, a natural piscicide used in fish management and the active ingredient in plants traditionally used by indigenous Hawaiians for capturing fish. To assess rotenone’s efficacy in killing tilapia and effects on non-target species, laboratory toxicity tests involved exposing organisms to various concentrations of liquid CFT Legumine (5% rotenone) in static trials of 48-h to 72-h duration. Test organisms included: Mozambique tilapia, non-native guppy Poecilia reticulata , the non-native odonate Rambur’s forktail Ischnura ramburii , native feeble shrimp Palaemon debilis , and native ‘ōpae’ula shrimp Halocaridina rubra . All organisms and water used in tests were obtained from ‘Aimakapā (12.6–12.7 ppt salinity), or, for H. rubra , an anchialine pool (15.0–15.2 ppt salinity). Survival analyses indicated CFT Legumine concentrations >3 ppm (>0.15 mg/L rotenone) achieved 100% mortality of tilapia and 93% of guppies within 24 h, with most tilapia killed by 6 h and most guppies by 2 h. Little or no mortality was observed among invertebrate exposed to 1 to 5 mg/L CFT Legumine: 0% mortality for ‘ōpae’ula shrimp, 4% for feeble shrimp; and 16% for odonate larvae. The 48 h LC50 values for Mozambique tilapia and guppy were 0.06 and 0.11 mg/L rotenone, respectively. Results demonstrate rotenone’s potential for non-native fish eradication in brackish-water habitats, with benefit of low mortality to certain macro-invertebrates. High rotenone tolerance displayed by ‘ōpae’ula shrimp is noteworthy. Invasive fish are common in anchialine pools, threatening existence of shrimp and other invertebrate fauna. Although rotenone’s effects on freshwater organisms have been well studied, our research represents one of only a few controlled laboratory experiments quantitatively assessing rotenone tolerance of brackish or marine fauna.

Hawaii↗

USGS2017

Increased sediment load during a large-scale dam removal changes nearshore subtidal communities

The coastal marine ecosystem near the Elwha River was altered by a massive sediment influx—over 10 million tonnes—during the staged three-year removal of two hydropower dams. We used time series of bathymetry, substrate grain size, remotely sensed turbidity, scuba dive surveys, and towed video observations collected before and during dam removal to assess responses of the nearshore subtidal community (3 m to 17 m depth). Biological changes were primarily driven by sediment deposition and elevated suspended sediment concentrations. Macroalgae, predominantly kelp and foliose red algae, were abundant before dam removal with combined cover levels greater than 50%. Where persistent sediment deposits formed, macroalgae decreased greatly or were eliminated. In areas lacking deposition, macroalgae cover decreased inversely to suspended sediment concentration, suggesting impacts from light reduction or scour. Densities of most invertebrate and fish taxa decreased in areas with persistent sediment deposition; however, bivalve densities increased where mud deposited over sand, and flatfish and Pacific sand lance densities increased where sand deposited over gravel. In areas without sediment deposition, most invertebrate and fish taxa were unaffected by increased suspended sediment or the loss of algae cover associated with it; however, densities of tubeworms and flatfish, and primary cover of sessile invertebrates increased suggesting benefits of increased particulate matter or relaxed competition with macroalgae for space. As dam removal neared completion, we saw evidence of macroalgal recovery that likely owed to water column clearing, indicating that long-term recovery from dam removal effects may be starting. Our results are relevant to future dam removal projects in coastal areas and more generally to understanding effects of increased sedimentation on nearshore subtidal benthic communities.

Washington↗

USGS2021

Near-field receiving-water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California—2019

Trace-metal concentrations in sediment and in the clam Limecola petalum (formerly reported as Macoma balthica and M. petalum ), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in south San Francisco Bay, Calif. This report includes the data collected by the U.S. Geological Survey (USGS) for the period January 2019 to December 2019. These data append to long-term datasets extending back to 1974. A major focus of the report is an integrated description of the 2019 data within the context of the longer, multidecadal dataset. This dataset supports the City of Palo Alto’s Near-Field Receiving-Water Monitoring Program, initiated in 1994. Significant reductions in silver and copper contamination occurred at the site in the 1980s following the implementation by PARWQCP of advanced wastewater treatment and source control measures. Since the 1990s, concentrations of these elements in surface sediments have continued to decrease, although more slowly. Silver appears to have stabilized at concentrations about twice the regional background concentration. Presently, sediment copper concentrations appear to be near the regional background level. Over the same period (1994–2019), sedimentary iron and zinc also exhibited modest declines. Sedimentary aluminum, chromium, mercury, nickel, and selenium have not exhibited any trend. Since 1994, concentrations of silver and copper in L. petalum have varied seasonally, apparently in response to a combination of site-specific metal exposures and cyclic growth and reproduction, as reported previously. Seasonal patterns for other elements, including chromium, mercury, nickel, selenium, and zinc, were generally similar in timing and magnitude as those for silver and copper. The annual growth and reproductive cycle explained a small amount of the variance in annual silver and zinc tissue metal concentrations. However, interannual trends are not apparent for any element. Biological effects of elevated silver and copper contamination at the Palo Alto site have been interpreted from data collected during and after the recession of these contaminants. Concentrations of both elements in the soft tissues of L. petalum declined with sedimentary copper and silver. This pattern was associated with changes in the reproductive activity of L. petalum , as well as the structure of the benthic invertebrate community. Reproductive activity of L. petalum increased as metal concentrations in L. petalum declined and presently is stable with almost all animals initiating reproduction in the fall and spawning the following spring. Analyses of the benthic community structure indicate that the infaunal invertebrate community has shifted from one dominated by several opportunistic species when silver and copper exposures were highest to one in which the species abundance is more evenly distributed, a pattern that indicates a more stable community that is subjected to fewer stressors. Importantly, this long-term change is unrelated to other metals and other measured environmental factors, including salinity and sediment composition. In addition, two of the opportunistic species ( Ampelisca abdita and Streblospio benedicti ) that brood their young and live on the surface of the sediment in tubes have shown a continual decline in dominance coincident with the decline in metals. Both species had short-lived rebounds in abundance in 2008, 2009, and 2010 and showed signs of increasing abundance in 2019. Heteromastus filiformis (a subsurface polychaete worm that lives in the sediment, consumes sediment and organic particles residing in the sediment, and reproduces by laying its eggs on or in the sediment) showed a concurrent increase in dominance and, in the last several years before 2008, showed a stable population. H. filiformis abundance increased slightly in 2011–2012 and returned to pre-2011 numbers in 2019. An unidentified disturbance occurred on the mudflat in early 2008 that resulted in the loss of the benthic animals, except for deep-dwelling animals like L. petalum . However, within two months of this event, animals returned to the mudflat. The resilience of the community suggested that the disturbance was not caused by a persistent toxin or anoxia. The reproductive mode of most species that were present in 2019 was indicative of species that were available either as pelagic larvae or as mobile adults. Although oviparous species were lower in number in this group, the authors hypothesize that these species will return slowly as more species move back into the area. The use of functional ecology was highlighted in the 2019 benthic community data, which showed that the animals that have now returned to the mudflat are those that can respond successfully to a physical, nontoxic disturbance. Today, community data show a mix of species that consume the sediment, or filter feed, those that have pelagic larvae that must survive landing on the sediment, and those that brood their young. USGS scientists view the 2008 disturbance event as a response by the infaunal community to an episodic natural stressor (possibly sediment accretion or a pulse of freshwater), in contrast to the long-term recovery from metal contamination. We will compare this recovery to the long-term recovery observed after the 1970s when the decline in sediment pollutants was the dominating factor.

California↗

USGS2023

Near-field receiving-water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California—2020

Trace-metal concentrations in sediment and in the clam Limecola petalum (World Register of Marine Species, 2020; formerly reported as Macoma balthica and M. petalum ), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer (km) south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in south San Francisco Bay, California. This report includes the data collected by the U.S. Geological Survey (USGS) for January 2020–December 2020 (Cain and others, 2022). These data append to long-term datasets extending back to 1974. A major focus of the report is an integrated description of the 2020 data within the context of the longer, multidecadal dataset. This dataset supports the City of Palo Alto’s Near-Field Receiving- Water Monitoring Program, initiated in 1994. Silver and copper contamination substantially decreased at the site in the 1980s following the implementation by PARWQCP of advanced wastewater-treatment and source-control measures. Since the 1990s, concentrations of these elements in surface sediments have continued to decrease, although more slowly. For example, from 1994 to 2020, the minimum annual mean silver concentration—0.20 milligram per kilogram (mg/kg)—was observed in multiple years. In 2020, silver concentrations ranged from 0.18 to 0.28 mg/kg. These concentrations are 2 to 3 times higher than the regional background concentration. Presently (2020), sediment-copper concentrations appear to be near the regional background level. Over the same period (1994–2020), sedimentary iron and zinc exhibited modest decreases. Sedimentary aluminum, chromium, mercury, nickel, and selenium have not exhibited any trend. Since 1994, silver and copper concentrations in L. petalum have varied seasonally, apparently in response to a combination of site-specific metal exposures and cyclic growth and reproduction, as reported previously. Seasonal patterns for other elements, including chromium, mercury, nickel, selenium, and zinc, generally were similar in timing and magnitude as those for silver and copper. Downward trends in the silver and zinc concentrations in L. petalum during 1994–2020 were evident and appeared to be related to the general physiological condition of the clam, indicated by a condition index. Biological effects of elevated silver and copper contamination at the Palo Alto site have been interpreted from data collected during and after the recession of these contaminants. Concentrations of both elements in the soft tissues of L. petalum decreased with sedimentary copper and silver. This pattern was associated with changes in the reproductive activity of L. petalum , as well as the structure of the benthic invertebrate community. Reproductive activity of L. petalum increased as metal concentrations in L. petalum decreased (Hornberger and others, 2000), and presently is stable with almost all animals initiating reproduction in the fall and spawning the following spring. Analyses of the benthic community structure indicate that the infaunal invertebrate community has shifted from one dominated by several opportunistic species when silver and copper exposures were highest to one in which the species abundance is more evenly distributed, a pattern that indicates a more stable community that is subjected to fewer stressors. Importantly, this long-term change is unrelated to other metals and other measured environmental factors, including salinity and sediment composition. In addition, two of the opportunistic species ( Ampelisca abdita and Streblospio benedicti ) that brood their young and live on the surface of the sediment in tubes have shown a continual decrease in dominance coincident with the decrease in metals. Both species had short-lived rebounds in abundance in 2008, 2009, and 2010 and showed signs of increasing abundance in 2020. Heteromastus filiformis (a subsurface polychaete worm that lives in the sediment, consumes sediment and organic particles residing in the sediment, and reproduces by laying its eggs on or in the sediment) showed a concurrent increase in dominance and, in the last several years before 2008, showed a stable population. H. filiformis abundance increased slightly from 2011 to 2012 and returned to pre-2011 numbers in 2020. The reproductive mode of most species that were present in 2020 was indicative of species that were capable of movement either as pelagic larvae or as mobile adults. Although oviparous species were lower in number in this group, the authors hypothesize that these species will return slowly as more species move back into the area. The use of functional ecology was highlighted in the 2020 benthic community data, which showed that the animals that have now returned to the mudflat are those that can respond successfully to a physical, nontoxic disturbance. Today, community data show a mix of species that consume the sediment, or filter feed, those that have pelagic larvae that must survive landing on the sediment, and those that brood their young. The long-term recovery observed after the 1970s can be ascribed to the decrease in sediment pollutants.

California↗

USGS2015

Oyster reef restoration supports increased nekton biomass and potential commercial fishery value

Across the globe, discussions centered on the value of nature drive many conservation and restoration decisions. As a result, justification for management activities increasingly asks for two lines of evidence: (1) biological proof of augmented ecosystem function or service, and (2) monetary valuation of these services. For oyster reefs, which have seen significant global declines and increasing restoration work, the need to provide both biological and monetary evidence of reef services on a local-level has become more critical in a time of declining resources. Here, we quantified species biomass and potential commercial value of nekton collected from restored oyster ( Crassostrea virginica ) reefs in coastal Louisiana over a 3-year period, providing multiple snapshots of biomass support over time. Overall, and with little change over time, fish and invertebrate biomass is 212% greater at restored oyster reefs than mud-bottom, or 0.12 kg m −2 . The additional biomass of commercial species is equivalent to an increase of local fisheries value by 226%, or $0.09 m −2 . Understanding the ecosystem value of restoration projects, and how they interact with regional management priorities, is critical to inform local decision-making and provide testable predictions. Quantitative estimates of potential commercial fisheries enhancement by oyster reef restoration such as this one can be used directly by local managers to determine the expected return on investment.

Louisiana↗