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At least 307 records · Page 17Linked to original sources
USGS1995

Effect of the Cedar River on the quality of the ground-water supply for Cedar Rapids, Iowa

The Surface Water Treatment Rule under the 1986 Amendment to the Safe Drinking Water Act requires that public-water supplies be evaluated for susceptibility to surface-water effects. The alluvial aquifer adjacent to the Cedar River is evaluated for biogenic material and monitored for selected water-quality properties and constituents to determine the effect of surface water on the water supply for the City of Cedar Rapids, Iowa. Results from monitoring of selected water-quality properties and constituents showed an inverse relation to river stage or discharge. Water-quality properties and constituents of the alluvial aquifer changed as water flowed from the river to the municipal well as a result of drawdown. The values of specific conductance, pH, temperature, and dissolved oxygen at observation well CRM-4 and municipal well Seminole 10 generally follow the trends of values for the Cedar River. Values at observation well CRM-3 and the municipal water-treatment plant showed very little correlation with values from the river. The traveltime of water through the aquifer could be an indication of the susceptibility of the alluvial aquifer to surface-water effects. Estimated traveltimes from the Cedar River to municipal well Seminole 10 ranged from 7 to 17 days. Above-normal streamflow and precipitation during the study could have increased the effect the river had on the alluvial aquifer and on the possibility of contamination by a pathogen. Microscopic particulate analysis of 29 samples found no Giardia cysts or Crytosporidium oocysts in water collected from municipal wells. Data also indicate that the aquifer is filtering out large numbers of algae, diatoms, rotifers, and nematodes as well as filtering out Cryptosporidium , Giardia , and other protozoa. The number of algae, diatoms, rotifers, protozoa, and vegetative debris for selected municipal wells tested showed at least a reduction to 1 per 1,000 of the number found in the river. A relative risk factor and a log-reduction rate were determined for the aquifer in the vicinity of selected wells. One municipal well had a high-risk factor, three other wells had a moderate-risk factor, and four wells had a low-risk factor. The filtering efficiency of the aquifer is equivalent to a 3 log-reduction rate or 99.99-percent reduction in particulates.

Iowa↗
USGS1996

Initial effects of Stagecoach Reservoir on discharge, water-quality characteristics, and suspended-sediment loads in the Yampa River, northwestern Colorado

The construction and filling of Stagecoach Reservoir on the Yampa River during 1988-91 were done to enhance water management and to use local water resources. To assess the initial effects of the reservoir on the hydrology of the upper Yampa River, physical, chemical, and biological data were collected at a site upstream (YR-1) during water years 1989-92 and a site downstream (YR-2) from the reservoir during water years 1985-92 and at two sites in the reservoir during 1990-92. Annual suspended-sediment loads were determined for the Yampa River for water years 1985-92, and sediment retention in Stagecoach Reservoir was estimated. The initial filling of the 33,275-acre-foot reservoir proceeded slower than expected because inflow from the Yampa River was about 50 to 73 percent of average during water years 1989-91. Secchi-disk measurements in Stagecoach Reservoir ranged from 2.5 to 18 feet. Algal growth and sediment transport during stormy weather decreased water clarity, and possible algal grazing by zooplankton and sediment deposition improved water clarity. Water temperature in the reservoir ranged from 0 to 22 degrees Celsius, and thermal stratification was maintained during summer. Values of pH ranged from 7.2 in the hypolimnion to 8.9 in the epilimnion. Changes in pH were related to photosynthesis and respiration. Concentrations of dissolved oxygen in the reservoir ranged from 0 milligram per liter in the hypolimnion to 13 milligrams per liter in the epilimnion. Average 5-day biochemical-oxygen-demand rates ranged from 0.33 to 0.46 milligram per liter per day. Oxygen production from photosynthesis was greatest in the epilimnion; oxygen depletion from respiration was characteristic in the hypolimnion. Near or above average inflow might decrease the incidence of anaerobic conditions. Specific conductance in the reservoir ranged from 414 to 520 microsiemens per centimeter at 25 degrees Celsius, depending on the specific conductance of inflow from the Yampa River. The water was a very hard, calcium bicarbonate type. Nitrogen input to the reservoir was mostly as organic nitrogen that ranged in concentration from less than 0.18 to about 1.0 milligram per liter. Concentrations of dissolved phosphorus in the inflow of the Yampa River ranged from less than 0.01 to 0.06 milligram per liter. Decomposition of organic material and release of nutrients from sediments under reducing conditions were probable causes for dissolved-ammonia concentrations near the reservoir bottom to increase to maximum values of 0.9 to 1.6 milligrams per liter as nitrogen during thermal stratification in summer. Dissolved phosphorus also increased in the same conditions to a range of 0.32 to 0.35 milligram per liter. Except for concentrations of total recoverable manganese that ranged from 210 to 440 micrograms per liter near the reservoir bottom, most concentrations of 20 trace constituents were measured at or near analytical detection limits. A total of 119 phytoplankton from 7 phyla was identified in Stagecoach Reservoir during 1990-92. Cyanophyta (blue-green algae) accounted for most of the cell counts. Cyanophyta blooms of Aphanizomenon and Aphanocapsa developed during 1990-92, and photosynthesis caused concentrations of dissolved oxygen to exceed 150-percent saturation in the epilimnion. Diversity index values for phytoplankton ranged from 0.05 to 3.06. Values of diversity index during the summer of 1992 indicated that the community diversity of algae could be greatest in spring and least in fall. All colony counts of fecal coliform bacteria in the reservoir during 1990-92 were less than criteria limits set by the State of Colorado. During water years 1985-88 (preconstruction period), at a site on the Yampa River downstream from the proposed damsite, and water years 1989-92 (post-construction period), at a site upstream from the dam, annual loads of suspended sediment ranged from 2,480 to 22,650 tons. The average annual suspended-sediment load for th

Water-Resources Investigations Report↗
USGS1997

Distribution of fish, benthic invertebrate, and algal communities in relation to physical and chemical conditions, Yakima River basin, Washington, 1990

Biological investigations were conducted in the Yakima River Basin, Washington, in conjunction with a pilot study for the U.S. Geological Survey's National Water-Quality Assessment Program. Ecological surveys were conducted at 25 sites in 1990 to (1) assess water-quality conditions based on fish, benthic invertebrate, and algal communities; (2) determine the hydrologic, habitat, and chemical factors that affect the distributions of these organisms; and (3) relate physical and chemical conditions to water quality. Results of these investigations showed that land uses and other associated human activities influenced the biological characteristics of streams and rivers and overall water-quality conditions. Fish communities of headwater streams in the Cascades and Eastern Cascades ecoregions of the Yakima River Basin were primarily composed of salmonids and sculpins, with cyprinids dominating in the rest of the basin. The most common of the 33 fish taxa collected were speckled dace, rainbow trout, and Paiute sculpin. The highest number of taxa (193) was found among the inverte- brates. Insects, particularly sensitive forms such as mayflies, stoneflies, and caddisflies (EPT--Ephemeroptera, Plecoptera, and Trichoptera fauna), formed the majority of the invertebrate communities of the Cascades and Eastern Cascades ecoregions. Diatoms dominated algal communities throughout the basin; 134 algal taxa were found on submerged rocks, but other stream microhabitats were not sampled as part of the study. Sensitive red algae and diatoms were predominant in the Cascades and Eastern Cascades ecoregions, whereas the abundance of eutrophic diatoms and green algae was large in the Columbia Basin ecoregion of the Yakima River Basin. Ordination of physical, chemical, and biological site characteristics indicated that elevation was the dominant factor accounting for the distribution of biota in the Yakima River Basin; agricultural intensity and stream size were of secondary importance. Ordination identified three site groups and three community types. Site groups consisted of (1) small streams of the Cascades and Eastern Cascades ecoregions, (2) small streams of the Columbia Basin ecoregions, and (3) large rivers of the Cascades and Columbia Basin ecoregions. The small streams of the Columbia Basin could be further subdivided into two groups--one where agricultural intensity was low and one where agricultural intensity was moderate to high. Dividing the basin into these three groups removed much of the influence of elevation and facilitated the analysis of land-use effects. Community types identified by ordination were (1) high elevation, cold-water communities associated with low agricultural intensity; (2) lower elevation, warm-water communities associated with low agricultural intensity, and (3) lower elevation, warm-water communities associated with moderate to high agricultural intensity. Multimetric community condition indices indicated that sites in the Cascades and Eastern Cascades site group were largely unimpaired. In contrast, all but two sites in the Columbia Basin site group were impaired, some severely. Agriculture (nutrients and pesticides) was the primary factor responsible for this impairment, and all impaired sites were characterized by multiple indicators of impairment. Three sites (Granger Drain, Moxee Drain, and Spring Creek) had high levels of impairment. Sites in the large-river site group were moderately to severely impaired downstream from the city of Yakima. High levels of impairment at large-river sites corresponded with high levels of pesticides in fish tissues and the occurrence of external anomalies.

Washington↗
USGS1998

Nutrient loading and selected water-quality and biological characteristics of Dickinson Bayou near Houston, Texas, 1995-97

Data were collected at 10 stations in the Dickinson Bayou watershed near Houston, Texas, from March 1995 through February 1997 to estimate the concentrations, loads, and yields of selected nutrients that enter the bayou; to characterize the effects on nutrient concentrations of flow conditions, seasonality, and land use; and to identify nutrient sources (point or nonpoint) inferred from the occurrence and abundance of algal species in the benthic algal community. These data included rainfall samples, streamflow measurements, stream-water-quality samples, and biological samples, in addition to quality-assurance/quality-control samples. Estimates of loads of selected nutrients for the 106-square-mile watershed during the study were made for point sources and nonpoint sources. Point-source loading data are available only for ammonia nitrogen. Approximately 21.3 pounds per day of ammonia nitrogen is estimated from point sources during the study period. Nonpoint-source loads are estimated for eight nutrient forms: 7.84 pounds per day of dissolved ammonia nitrogen, 5.79 pounds per day of dissolved nitrite nitrogen, 215 pounds per day of dissolved Kjeldahl nitrogen, 350 pounds per day of total Kjeldahl nitrogen, 40.1 pounds per day of dissolved nitrite plus nitrate nitrogen, 67.6 pounds per day of total phosphorus, 46.6 pounds per day of dissolved phosphorus, and 42.8 pounds per day of dissolved orthophosphate. Rainfall-deposition rates also are estimated for comparison with point- and nonpoint-source loads. Deposition rates are 110 pounds per day of dissolved ammonia nitrogen, 120 pounds per day of dissolved nitrate nitrogen, and 15.8 pounds per day of dissolved phosphorus. Statistical tests were used to determine whether there are significant differences between nutrient concentrations during low-flow and during high-flow conditions. For basins with rural/mixed and urban land uses, nutrient concentrations generally are significantly different (greater) during storm events than during low flow, indicating accumulation in the watershed and subsequent washoff of nutrients. However, nutrient concentrations in storm-event samples consisting predominantly of runoff from a pasture are not significantly greater than those in low-flow samples. Statistical tests for seasonality indicate that dissolved ammonia nitrogen is significantly different in at least one season for all land uses (rural/residential, rural/mixed, and pasture) except urban. Concentrations tend to increase in the spring and early summer months, possibly from fertilizer application and subsequent washoff. Constituent-yield data were used to make direct comparisons of the nonpoint-source load contributions from four stations with watersheds of different land use. These comparisons lead to three conclusions: (1) For all nutrient species except orthophosphate, urban land use is the largest nonpoint-source contributor, (2) Kjeldahl nitrogen is the most abundant nutrient species, and (3) organic nitrogen accounts for the major part of the Kjeldahl nitrogen. Algal samples were collected at seven stations and were analyzed for periphyton identification and enumeration, and chlorophyll a and chlorophyll b concentrations. The large relative abundance of soil algae at stations in the middle of the watershed likely indicates the cumulative effects on water quality of agricultural nonpoint sources. Farther downstream near the State Highway 3 bridge, and downstream of three major tributary inflows, the increase in abundance of soil algae to a larger-than-expected level might reflect water-quality influences from predominantly urban nonpoint sources in the drainage basins of the three major tributary inflows. Nutrient concentrations do not appear to limit algal production in the upper (non-tidal) reach of Dickinson Bayou; but nutrient concentrations could have been limiting benthicalgal production in the lower (tidal) reach of the bayou during the time of the synoptic survey. If nitrogen is the limiting resource for algal productivity in the tidal reach of Dickinson Bayou, eutrophication of the system could be (at least partially) mitigated if nonpoint-source nutrient loads into the Bayou were reduced.

Texas↗
USGS1998

Detailed study of selenium and selected constituents in water, bottom sediment, soil, and biota associated with irrigation drainage in the San Juan River area, New Mexico, 1991-95

In response to increasing concern about the quality of irrigation drainage and its potential effects on fish, wildlife, and human health, the U.S. Department of the Interior began the National Irrigation Water Quality Program (NIWQP) to investigate these concerns at irrigation projects sponsored by the Department. The San Juan River area in northwestern New Mexico was one of the areas designated for study. Study teams composed of scientists from the U.S. Geological Survey, the U.S. Fish and Wildlife Service, the Bureau of Reclamation, and the Bureau of Indian Affairs collected water, bottom-sediment, soil, and biological samples at 61 sites in the San Juan River area during 1993-94. Supplemental data collection conducted during 1991-95 by the Bureau of Indian Affairs and its contractor extended the time period and sampling sites available for analysis. Analytical chemistry performed on samples indicated that most potentially toxic elements other than selenium generally were not high enough to be of concern to fish, wildlife, and human health. Element concentrations in some water, bottom-sediment, soil, and biological samples exceeded applicable standards and criteria suggested by researchers in current literature. Selenium concentrations in water samples from 28 sites in the study area exceeded the 2-microgramper-liter (lg/L) wildlife-habitat standard. Vanadium concentrations in water exceeded the 100-Kg/L standard for livestock-drinking water at one site. In biota, selenium and aluminum concentrations regularly equaled or exceeded avian dietary threshold concentrations. In bottom sediment and soil, element concentrations above the upper limit of the baseline range for western soils were: selenium, 24 exceedances; lead, 2 exceedances; molybdenum, 2 exceedances;strontium, 4 exceedances; and zinc, 4 exceedances. Concentrations of total selenium in bottom-sediment and soil samples were significantly greater for Cretaceous than for non-Cretaceous soil types in the study area and were generally similar for habitats within and outside irrigation-affected areas. Mean and median total-selenium concentrations in samples from areas with Cretaceous soil types were 4.6 and 2.2 micrograms per gram (ps/g), respectively. Mean and median total-selenium concentrations in samples from areas with non-Cretaceous soil types were 0.6 and 0.15 pg/g, respectively. Samples from the study area had low concentrations of organic constituents. Organochlorine pesticides and polychlorinated biphenyls were detected in a few biological samples at low concentrations. Polycyclic aromatic hydrocarbon (PAH) compounds were not detected in whole-water samples collected using conventional water-sampling techniques. In tests involving the use of semipermeable-membrane devices to supplement conventional water assays for PAH's, low concentrations of PAH's were found at several locations in the Hammond Irrigation Supply Canal, but were not detected in the Hammond ponds at the downstream reach of the Hammond irrigation service area. PAH compounds do not appear to reach the San Juan River through the Hammond Canal. Data indicate that water samples from irrigation-drainage-affected habitats had increased mean selenium concentrations compared with samples from irrigation-delivery habitat. The mean selenium concentration in water was greatest at seeps and tributaries draining irrigated land (17 μg/L); less in irrigation drains and in ponds on irrigated land (61.tg/L); and least in backwater, the San Juan River, and irrigation-supply water (0.5 - 0.6 μg/L). Statistical tests imply that irrigation significantly increases selenium concentrations in water samples when a Department of the Interior irrigation project is developed on selenium-rich sediments. Water samples from sites with Cretaceous soils had significantly greater selenium concentrations than water samples from sites with non-Cretaceous soils. Water samples from Department of the Interior project irrigation-drainage sites developed on Cretaceous soils contained a mean selenium concentration about 10 times greater than those in samples from Department of the Interior project sites developed on non-Cretaceous soils. Selenium was much less concentrated in water than in bottom sediment, soil, or biota in the study area. The range in concentrations of dissolved selenium in water was less than 1 ptg/L to 37 1.1g/L (less than 1 to 37 parts per billion). The range in concentrations of total selenium in bottom sediment and soil was less than 0.1 to 23lig/g (less than 100 to 23,000 parts per billion). The range in concentration of selenium in biota was less than 0.1 to 24.0 fig/g (less than 100 to 24,000 parts per billion). Data indicated that bioaccumulation and leaching from soil were the important processes at the study area that lead to elevated levels of selenium. Other processes examined included: (1) evapoconcentration of selenium; (2) atmospheric deposition of aerosols containing selenium; and (3) contamination of surface water by point-source or non-point-source discharges. Selenium concentrations in biological samples were evaluated by a number of variables including: (1) media sampled (emergent and submergent plants, nektonic and benthic invertebrates, omnivore/herbivore and carnivore fish, and terrestrial and aquatic amphibians); (2) habitat (San Juan River main-stem reaches, backwaters, tributary reaches, irrigation delivery or drainage canals, and ponds); (3) irrigation project area and reference sites; and (4) soil type (non-Cretaceous or Cretaceous soils). Graphical techniques and nonparametric statistical tests were applied to determine the influence of selected physiographic variables on selenium concentrations in biological samples collected in the San Juan River area. Species of sucker and of smaller fish contained significantly higher selenium concentrations in the upstream portion of the river where a productive community of plants and animals is found that is associated with warming, nutrient-rich waters discharged from an upstream reservoir. Selenium concentrations in algae, odonates, and mosquitofish collected from both irrigation-drain and pond habitats underlain by Cretaceous soils were significantly greater than in those collected from similar habitats underlain by non-Cretaceous soils. Investigators conclude that the major factor affecting the variability of selenium accumulation in biota at aquatic habitats was the presence of underlying Cretaceous soils. Median selenium concentrations were less than 2 lAg/g for plant samples, less than 7 μg/g for invertebrate samples, and less than 6 lAg/g for whole-fish samples collected from aquatic habitats underlain by non-Cretaceous soils. Similar samples collected from aquatic habitats underlain by Cretaceous soils contained median selenium concentrations two to five times greater. Leaching of selenium from Cretaceous soils in the San Juan River area increases the accumulation of selenium concentrations in the biota and thereby increases the exposure and potential health risks associated with selenium to migratory birds, fish, and other wildlife that use these aquatic habitats extensively. Aquatic habitats presenting the greatest average exposure to excess selenium concentrations in the diets of resident wildlife are from consumption of plants, invertebrates, and fish at irrigation-drain habitats underlain by Cretaceous soils. Of the irrigation projects evaluated in the San Juan River area, the highest median selenium concentrations in algae, cattail leaves, odonate nymphs, mosquitofish, and leopard frog samples from the study area were collected from the east hogback irrigation drain.

New Mexico↗
USGS2006

Inhibition of coral recruitment by macroalgae and cyanobacteria

Coral recruitment is a key process in the maintenance and recovery of coral reef ecosystems. While intense competition between coral and algae is often assumed on reefs that have undergone phase shifts from coral to algal dominance, data examining the competitive interactions involved, particularly during the larval and immediate post-settlement stage, are scarce. Using a series of field and outdoor seawater table experiments, we tested the hypothesis that common species of macroalgae and cyanobacteria inhibit coral recruitment. We examined the effects of Lyngbya spp., Dictyota spp., Lobophora variegata (J. V. Lamouroux) Womersley, and Chondrophycus poiteaui (J. V. Lamouroux) Nam (formerly Laurencia poiteaui) on the recruitment success of Porites astreoides larvae. All species but C. poiteaui caused either recruitment inhibition or avoidance behavior in P. astreoides larvae, while L. confervoides and D. menstrualis significantly increased mortality rates of P. astreoides recruits. We also tested the effect of some of these macrophytes on larvae of the gorgonian octocoral Briareum asbestinum. Exposure to Lyngbya majuscula reduced survival and recruitment in the octocoral larvae. Our results provide evidence that algae and cyanobacteria use tactics beyond space occupation to inhibit coral recruitment. On reefs experiencing phase shifts or temporary algal blooms, the restocking of adult coral populations may be slowed due to recruitment inhibition, thereby perpetuating reduced coral cover and limiting coral community recovery. ?? Inter-Research 2006.

Marine Ecology Progress Series↗
USGS2003

Phytoplankton fuels Delta food web

Populations of certain fishes and invertebrates in the Sacramento-San Joaquin Delta have declined in abundance in recent decades and there is evidence that food supply is partly responsible. While many sources of organic matter in the Delta could be supporting fish populations indirectly through the food web (including aquatic vegetation and decaying organic matter from agricultural drainage), a careful accounting shows that phytoplankton is the dominant food source. Phytoplankton, communities of microscopic free-floating algae, are the most important food source on a Delta-wide scale when both food quantity and quality are taken into account. These microscopic algae have declined since the late 1960s. Fertilizer and pesticide runoff do not appear to be playing a direct role in long-term phytoplankton changes; rather, species invasions, increasing water transparency and fluctuations in water transport are responsible. Although the potential toxicity of herbicides and pesticides to plank- ton in the Delta is well documented, the ecological significance remains speculative. Nutrient inputs from agricultural runoff at current levels, in combination with increasing transparency, could result in harmful algal blooms.

California↗
USGS2009

Detection and characterization of benthic filamentous algal stands ( Cladophora sp.) on rocky substrata using a high-frequency echosounder

A high-frequency echosounder was used to detect and characterize percent cover and stand height of the benthic filamentous green alga Cladophora sp. on rocky substratum of the Laurentian Great Lakes. Comparisons between in situ observations and estimates of the algal stand characteristics (percent cover, stand height) derived from the acoustic data show good agreement for algal stands that exceeded the height threshold for detection by acoustics (~7.5 cm). Backscatter intensity and volume scattering strength were unable to provide any predictive power for estimating algal biomass. A comparative analysis between the only current commercial software (EcoSAV™) and an alternate method using a graphical user interface (GUI) written in MATLAB® confirmed previous findings that EcoSAV functions poorly in conditions where the substrate is uneven and bottom depth changes rapidly. The GUI method uses a signal processing algorithm similar to that of EcoSAV but bases bottom depth classification and algal stand height classification on adjustable thresholds that can be visualized by a trained analyst. This study documents the successful characterization of nuisance quantities of filamentous algae on hard substrate using an acoustic system and demonstrates the potential to significantly increase the efficiency of collecting information on the distribution of nuisance macroalgae. This study also highlights the need for further development of more flexible classification algorithms that can be used in a variety of aquatic ecosystems.

Great Lakes↗
USGS2024

Software application for spectral mixture analysis for surveillance of harmful algal blooms (SMASH): A tool for identifying cyanobacteria genera from remotely sensed data

Remote sensing is often used to detect algae, but standard techniques do not provide information on the types of algae present or their potential to form a harmful algal bloom (HAB). We developed a framework for identifying algal genera based on reflectance: SMASH, short for Spectral Mixture Analysis for Surveillance of HABs. The Software Application for SMASH (SAS) was developed in MATLAB and makes use of a Multiple Endmember Spectral Mixture Analysis (MESMA) algorithm implemented in Python but packaged as a standalone executable. SAS includes functions for importing hyperspectral images, resampling spectral libraries, evaluating endmember spectral separability, performing MESMA, and generating various output data products.

Journal of Open Research Software (JORS)↗
USGS2013

Environmental factors that influence cyanobacteria and geosmin occurrence in reservoirs

Phytoplankton are small to microscopic, free-floating algae that inhabit the open water of freshwater, estuarine, and saltwater systems. In freshwater lake and reservoirs systems, which are the focus of this chapter, phytoplankton communities commonly consist of assemblages of the major taxonomic groups, including green algae, diatoms, dinoflagellates, and cyanobacteria. Cyanobacteria are a diverse group of single-celled organisms that can exist in a wide range of environments, not just open water, because of their adaptability [1-3]. It is the adaptability of cyanobacteria that enables this group to dominate the phytoplankton community and even form nuisance or harmful blooms under certain environmental conditions [3-6]. In fact, cyanobacteria are predicted to adapt favorably to future climate change in freshwater systems compared to other phytoplankton groups because of their tolerance to rising temperatures, enhanced vertical thermal stratification of aquatic ecosystems, and alterations in seasonal and interannual weather patterns [7, 8]. Understanding those environmental conditions that favor cyanobacterial dominance and bloom formation has been the focus of research throughout the world because of the concomitant production and release of nuisance and toxic cyanobacterial-derived compounds [4-6, 7-10]. However, the complex interaction among the physical, chemical, and biological processes within lakes, reservoirs, and large rivers often makes it difficult to identify primary environmental factors that cause the production and release of these cyanobacterial by-products.

South Carolina↗
USGS2017

Baseline assessments for coral reef community structure and demographics on West Maui

The coastal and upslope terrains of West Maui have had a long history of impacts owing to more than a century of human activities. Resource extraction, agriculture, as well as residential and resort development have caused land-based pollution that impairs water quality and adversely impact the adjacent marine ecosystem. Today, West Maui’s coral reefs are chronically impacted by the effects of land-based pollution, mainly sedimentation and nutrients, with documented losses of 30 – 75% in coral cover over the last 20 years. Nonetheless, despite their current status and levels of environmental impact, these coral reef communities represent a key local resource and a counterpoint to the overall low coral reef development levels both island- and state-wide. This is of high relevance because the occurrence of coral-rich assemblages and accreted reef complexes statewide is sparse. Only limited segments along the coastlines of Maui, Hawai‘i, Lana‘i, Moloka‘i, and Kaho‘olawe, harbor mature, fringing coral reefs; and unfortunately, many of them are seriously threatened by terrestrial runoff. This report describes the results of baseline assessment surveys of coral reef benthic structure, coral community demographics, and coral condition. These surveys are intended to provide benchmarks for continued monitoring efforts and provide a gauge for comparing and evaluating the effectiveness of management actions to reduce land-based sources of pollution in priority watersheds on West Maui. Within this context, 12 permanent, long-term monitoring sites were strategically established adjacent to the 7 primary stream drainages (Wahikuli, Honokōwai, Mahinahina, Kahana/Ka‘opala, Honokeana, Honokahua, and Honolua) within the five priority watersheds (Wahikuli, Honokōwai, Kahana, Honokahua, and Honolua). Herein, benthic cover and composition, coral demographics, and coral condition of the monitoring sites are described and contrasted in the “Benthic Characterization” and “Synthesis and Discussion” sections of this report. The baseline assessments revealed that although some areas harbor prominent coral reef structures with high live coral cover and multispecies assemblages, others are characterized by sediment-impacted corals in impoverished and species-poor communities. Mean coral cover varied widely, from 49% at Wahikuli-shallow to 4.6% at Mahinahina-shallow. Similarly, coralline algal cover averaged 12.7% at Ka‘opala and Honokeana-north, but was altogether absent at the Mahinahina sites. Macroalgae was a minor component of the benthos across all study sites, representing only up to 2.3% at Mahinahina-south, while turf algae varied considerably, from 41% at Honokeana-north to 84% at the Honokahua site. Consequently, the Benthic Substrate Ratio (BSR) also varied considerably region wide, with the highest values (≥ 1), suggesting a healthier reef condition reported for the Wahikuli, Honokeana, and Honokōwai sites; and the lowest (≤ 0.5), suggesting impairment in structure and function, recorded at the Honolua and Honokahua sites. Adult colony densities were the highest at the Wahikuli (27 col/m 2 ) but lowest at the Ka‘opala (7 col/m2 ) site. And, colony partial mortality peaked at the Ka‘opala (33%) and was the lowest at the Honokeana Bay (12%). Moreover, in-situ and derived estimates of water turbidity and sediment loading revealed that the Ka‘opala and Wahikuli stream sites ranked the highest for turbidity, whereas the Honokōwai and Ka‘opala sites ranked highest for sediment loading. Chronic and episodic terrestrial sediment stress has resulted in coral reef community demise, clearly illustrated at the Honolua, Honokahua, and Ka‘opala sites, where coral benthic cover and colony abundances ranked the lowest and levels of turf algae ranked among the highest. Left unattended, land-based pollution impacts will continue to negatively affect the coral reef communities of West Maui. And, under the current turbidity and sediment loading conditions, the coral-rich habitats in the Wahikuli and Honōkowai Watersheds are probably at greatest risk, given they harbor the most prominent and well-developed reefs in the region, characterized by the highest coral cover, colony densities, and structural complexity.

Hawaii↗
USGS1994

Vertical distribution of a deep-water moss and associated epiphytes in Crater Lake, Oregon

A one-person submersible was used to examine the vertical distribution of the deep-water moss Drepanocladus aduncus (Hedw.) Warnst in Crater Lake (Oregon). Living specimens were found attached to sediment and rocks at depths between 25 m and 140 m. Dense beds of the moss were observed at depths between 30 m and 80 m, a region that corresponded roughly to the zone of maximum primary production by phytoplankton. The moss population supported a diverse assemblage of epiphytic algae, of which the most abundant genera included Cladophora,Oedogonium, Rhizoclonium, Tribonema, Vaucheria, and the diatoms Cocconeis, Cymbella, Epithemia, Fragilaria, Gomphonema, Melosira, Navicula, and Synedra. Chemical and physical data supported the hypothesis that the lower limit of distribution of the moss is determined by light limitation, whereas the upper limit is related to the availability of nutrients, particularly nitrate-nitrogen and trace elements. Deep-water videotapes of the moss population indicated that D. aduncus with its epiphytic algae was abundant enough in regions associated with the metalimnion and upper hypolimnion to have a potential influence on the nutrient dynamics of the Crater Lake ecosystem. Although the maximum depth at which living bryophytes occur in Crater Lake is similar to that found for Lake Tahoe, conditions in Lake Tahoe allow the growth and survival of a much more diverse assemblage of bryophytes and charophytes than is present in Crater Lake.

Northwest Science↗
USGS1990

Sago pondweed (Potamogeton pectinatus L.): A literature review

Sago pondweed ( Potamogeton pectinatus L.) is a submersed macrophyte of nearly cosmopolitan distribution. The plant is of worldwide importance as a waterfowl food but also can be a nuisance in irrigation canals and recreational areas. The plant reproduces by many different means, depending on habitat and environmental stress. Several genetic ecotypes have evolved. Most important as waterfowl food are the turions (tubers), vegetative propagules rich in carbohydrates that are mostly buried in bottom sediments. In temperate wetlands, most turions sprout in spring, making sago behave as an annual. Drupelets (seeds) are the sexual propagules of sago and provide a mechanism for sago to survive periods of drought and excessive water salinity. Drupelets can be washed ashore or carried by birds for long distances. Sago decomposes rapidly at senescence, annually in temperate wetlands. Sago is mostly found in semipermanently or permanently flooded mixosaline lacustrine, palustrine, and riverine wetlands < 2.5 m deep, where fetches are not large or currents are < 1 m/s. Sago seems to prefer stable water levels but can tolerate significant water level fluctuations. Among the Potamogetons, only sago tolerates high salinity, pH, and alkalinity, but it fares poorly among specialist taxa in acidic or nutrient-poor waters. Sago is highly tolerant of eutrophic waters, and it can be the only species of submersed macrophyte present in heavily polluted sites. Sago grows in nearly all bottom substrates. Turbidity is the factor that most frequently limits sago growth. Sago often occurs in monotypic stands but can grow with many other submersed and emergent macrophytes. Dominance by sago in certain wetlands sometimes alternates with dominance by other submersed macrophytes when salinities or other environmental factors change. Sago also can be associated with a large variety of unattached filamentous, planktonic, or epiphytic algae. Increased turbidity caused by planktonic algae often is responsible for lowered sago production. Less common biotic limiting factors are organic pollutants and consumption and uprooting by waterfowl and fish. Sago provides food or shelter for amphibians, reptiles, fish, and mammals. The greatest value of sago in North America is as food for migrant and staging waterfowl, primarily diving ducks and swans. Sago beds also provide habitat for a large complex of invertebrates (an important food source for young waterfowl), but direct consumption of living sago by invertebrates is negligible. Sago has been propagated for many years-indoors, as an experimental organism for work in plant physiology or herbicide testing, and outdoors, for purposes of attracting waterfowl. Much work has also been done developing methods to control excessive sago growth in fishponds and irrigation canals. Future research should concentrate on (1) determining, in a variety of wetland types, the causes of light-limiting turbidity that often suppresses sago growth, (2) understanding the ways in which human activities on and near wetlands affect sago production, and (3) developing reliable and predictable techniques to stimulate sago production for waterfowl by using water level manipulations and other means, in a variety of environmental settings.

Resource Publication↗
USGS2003

Biorecovery of gold

Recovery of ionic and metallic gold (Au) from a wide variety of solutions by selected species of bacteria, yeasts, fungi, algae, and higher plants is documented. Gold accumulations were up to 7.0 g/kg dry weight (DW) in various species of bacteria, 25.0 g/kg DW in freshwater algae, 84.0 g/kg DW in peat, and 100.0 g/kg DW in dried fungus mixed with keratinous material. Mechanisms of accumulation include oxidation, dissolution, reduction, leaching, and sorption. Uptake patterns are significantly modified by the physicochemical milieu. Crab exoskeletons accumulate up to 4.9 g Au/kg DW; however, gold accumulations in various tissues of living teleosts, decapod crustaceans, and bivalve molluscs are negligible.

Indian Journal of Experimental Biology↗
USGS2000

Beach and reef-flat sediments along the south shore of Molokai, Hawaii

As part of the U.S. Geological Survey's multi-disciplinary Coral Reef Project addressing the health and geological variability of coral reef systems, sediment components and their distribution along the fringing reef on the south shore of the Hawaiian island of Molokai are being examined. Particular interest is being paid to the types and origin of sediment found on the reef. The south shore of Molokai is sheltered by one of the largest fringing reefs in the US. At approximately 50 km in length, up to 1.5 km in width, and covered by 90% live coral in many locations, the reef seemingly should be able to provide ample sediment for large carbonate beaches. However, siliciclastic grains supplied by erosion of the basaltic uplands of Molokai are often the most conspicuous individual nearshore sediment type. Coralline algae and coral are the most common carbonate components of the beaches. On the nearshore reef-flat, chemically-altered carbonate grains, particularly coralline algae, are the most abundant component. Molluscs and Halimeda may be common in specific locations, but are usually minor components. Sediment calcium carbonate levels increase to the west from a minimum at Kamalo, and are high along the east shore of Molokai. However, these general island-scale trends may be overridden by local influences, such as protected stream mouths or high carbonate growth rates. Additionally, trends seen on the beach and nearshore environments may not reflect trends a few hundred meters offshore since shore normal trends are more pronounced than shore parallel ones.

Conference Paper↗
USGS1990

Microphytic crusts: 'topsoil' of the desert

Deserts throughout the world are the home of microphytic, or cryptogamic, crusts. These crusts are dominated by cyanobacteria, previously called blue-green algae, and also include lichens, mosses, green algae, microfungi and bacteria. They are critical components of desert ecosystems, significantly modifying the surfaces on which they occur. In the cold deserts of the Colorado Plateau (including parts of Utah, Arizona, Colorado, and New Mexico), these crusts are extraordinarily well-developed, and may represent 70-80% of the living ground cover.

Permaculture Drylands Journal↗
USGS2001

Occurrence, distribution, and transport of nutrients in Eastern Iowa Rivers

Eleven streams in the Wapsipinicon, Cedar, Iowa, and Skunk River basins in eastern Iowa were sampled monthly from March 1996 through September 1998 to assess the occurrence, distribution, and transport of nitrogen, phosphorus, and suspended sediment as part of the U.S. Geological Survey's National Water-Quality Assessment Program. At least one form of dissolved nitrogen and phosphorus was detected in every sample collected. Nitrate accounted for 92 percent of the dissolved nitrogen. About 22 percent of the samples contained nitrate that exceeded the U.S. Environmental Protection Agency's Maximum Contaminant Level of 10 milligrams per liter (mg/L) as nitrogen in drinking water. The median concentration of total nitrogen for surface water in the study area was 7.2 mg/L. Dissolved phosphorus was predominately in the form of orthophosphate. The median total phosphorus concentration for the study area was 0.22 mg/L. About 75 percent of the total phosphorus concentrations exceeded the U.S. Environmental Protection Agency recommended total phosphorus concentration of 0.10 mg/L or less to minimize algal growth in streams not discharging directly into lakes or impoundments. Median suspended-sediment concentration for the study area was 82 mg/L. Nitrogen, phosphorus, and suspended-sediment concentrations varied annually and seasonally. Nitrogen, phosphorus, and suspended-sediment concentrations increased each year of the study due to increased precipitation and runoff. Concentrations were typically higher in the spring after fertilizer application and runoff. In winter, nitrogen concentrations typically increased when there was little instream assimilation by aquatic plants and algae. Nitrogen and phosphorus concentrations decreased in late summer when there was less runoff and instream assimilation of nitrogen and phosphorus by aquatic plants and algae was high. Suspended-sediment concentrations were highest in early summer during runoff and lowest in January when there was ice cover with very little overland flow contributing to rivers and streams. Streams draining small- to medium-sized watersheds that have uniform land use and geology had significantly (p < 0.05) higher total dissolved-nitrogen concentrations (median, 8.2 mg/L) than did samples from large rivers (median, 6.2 mg/L) that drain basins with mixed land use and geology. Samples from large rivers typically had significantly (p< 0.05) higher total phosphorus and suspended-sediment concentrations than did samples from small rivers and streams. Concentrations varied between drainage basins due to land use and physiography. Basins that are located in areas with a higher percentage of row-crop agriculture typically had samples with higher nitrogen concentrations than did basins with less row-crop agriculture. In addition, basins that drain the Southern Iowa Drift Plain and the Des Moines Lobe typically had samples with higher total phosphorus and suspended-sediment concentrations than did basins that drain other landform regions. Total nitrogen and total phosphorus loads were typically proportional to the size of the drainage basin. Total nitrogen loads increased each year from 1996 through 1998 in conjunction with increased concentrations and runoff. However, total phosphorus loads in the Skunk River Basin decreased in 1997 due to less runoff. Total phosphorus loads followed the same pattern as total nitrogen loads with increases in 1998. Total nitrogen and total phosphorus loads varied seasonally and the highest loads typically occurred in early spring and summer after fertilizer application and runoff. Loads were lowest in January and September when there was little runoff to transport nitrogen and phosphorus to the rivers and streams. Total nitrogen loads contributed to the Mississippi River from the Eastern Iowa Basins during 1996, 1997, and 1998 were 97,000, 120,000, and 230,000 metric tons respectively. Total phosphorus loads contributed to the Mississippi River from the Eastern Iowa Basins during 1996, 1997, and 1998 were 6,900, 4,600, and 8,800 metric tons, respectively. The highest nitrogen and phosphorus yields typically occurred in streams draining small watersheds that were dominated by a single land use and geology. Sampling sites located in drainage basins with higher row-crop percentage typically had higher nitrogen and phosphorus yields. Sites that were located in the Des Moines Lobe and the Southern Iowa Drift Plain typically had higher phosphorus yields probably due to more erodible soils and steeper slopes.

Iowa↗
USGS1976

Ecology of mangroves in the Jewfish Chain, Exuma, Bahamas

The structure and function of mangrove communities in the Jewfish Chain, Exumas, Bahamas, were investigated for 3-1/2 years. Mangrove vegetation in the Jewfish Chain is similar to that in all the Caribbean-Florida area; Rhizophora mangle L. dominates and is interspersed with Avicennia germinans (L.) Lamk. and Laguncularia racemosa (L.) Gaertn. There is no apparent zonation of these three species. The mangrove communities in the Jewfish Chain occur only where they are protected from prevailing winds, storms, and tides, although all are periodically devastated by hurricanes. We found little or no evidence of coast building within these protected locations. The importance of the mangroves appears to be in providing protection and food for other flora and fauna within this unique ecosystem. Twenty-four species of algae were found in the mangroves, 9 of which had not previously been reported from the Bahamas. Distribution of these algae appears to be correlated to incident solar radiation, desiccation, and tide level. A total of 56 species of fish were found in the mangroves, 2 of which were not previously known from the Bahamas. Many fish taken were juveniles, suggesting that mangroves are a nursery ground for numerous species. Nine species of molluscs were found. Each species had a distinct distribution pattern relative to distance from the seaward edge of the mangroves, as well as a distinct vertical distribution pattern. Seventeen species of decapod crustaceans were recorded. Though several species of birds were noted in the mangroves, three species were most abundant: the white-crowned pigeon ( Columba leucocephala ) uses the mangrove for nesting but feeds in nearby shrub-thorn communities; the gray kingbird ( Tyrannus dominicensis ) and green heron ( Butorides virescens ) nest and feed in the mangroves. Our data do not completely describe a stereotyped mangrove community in the Bahamas, but they do give an indication of community structure and suggest several aspects of function.

Conference Paper↗