Summer Water Temperatures Research Articles

Groundwater Upwelling Regulates Thermal Hydrodynamics and Salmonid Movements during High‐Temperature Events at a Montane Tributary Confluence

AbstractThe Smith River is a popular recreational sport fishery in western Montana, but salmonid abundances there are thought to be artificially limited by riparian land‐use alterations, irrigation water withdrawals, and high summer water temperatures. We used integrated networks of temperature loggers, PIT tag antenna stations, and in situ temperature mapping to investigate the thermal hydrodynamics and associated movements of PIT‐tagged salmonids at the confluence of Tenderfoot Creek, a major, unaltered coldwater tributary of the Smith River. Contrary to expectations, Tenderfoot Creek itself was not used as a thermal refuge by salmonids during periods of high water temperatures in Smith River; rather, its cool outflow plume into the main stem was used instead. Mean daily outflow water temperatures averaged 2.9°C lower than those of the Smith River during summer and ranged from 0.5°C to 6.1°C lower. Moreover, measured and estimated temperatures in the outflow were cooler (by up to 2.8°C) than in Tenderfoot Creek itself at times as a result of groundwater upwelling at the confluence. Detections of PIT‐tagged fish in the thermal plume increased, especially at night, when daily mean water temperatures exceeded 20°C in the main‐stem Smith River; more than four times as many PIT‐tagged fish were detected in the plume (N = 52) than along the opposite bank (N = 12), which ostensibly afforded better cover. Coldwater tributary confluences may provide superior thermal refuges for salmonids—cooler than the tributaries themselves—when water temperatures in river main stems are stressful.

High-Frequency Data for Temperature and Oxygen Reveal the Potential for Stressful Conditions for Fish in a Southern New England Impoundment

Fishes have specific dissolved oxygen and water temperature requirements needed to promote optimal growth. Ongoing anthropogenic climate change will lead to increased water temperature and likely changes in dissolved oxygen concentrations that will affect fish populations in a variety of ways. This study uses high-frequency, automated sensor data from 2011–2015 to examine dissolved oxygen and water temperature in Lake Lillinonah, a hydroelectric impoundment in western Connecticut, to identify potentially stressful conditions for Esox lucius (Northern Pike [NP]) and Micropterus salmoides (Largemouth Bass [LMB]). We found that summer water temperature was nearly always in an optimal range for LMB growth, but was frequently in the stressful range for NP growth. In addition, in some years, Lake Lillinonah experienced consistent hypoxia, reducing the thermal refuge available for NP. Long-term data from Lake Lillinonah show an increase in mean July surface water temperature, and further temperature increases are expected as the climate continues to warm. This trend, coupled with a potential reduction in thermal refuge due to hypoxia, poses serious consequences for NP, given that current conditions frequently exceed documented optimal growth range for the species.

Assessing water conditions for Heleophryne rosei tadpoles and the conservation relevance

The Table Mountain Ghost Frog (Heleophryne rosei) is endemic to the Table Mountain massif and is Critically Endangered. Other than clear, clean perennial stream flow, the optimal aquatic conditions required by their larvae are unknown. Dissolved oxygen, temperature, pH, electro-conductivity, aspect and permanence of flow are the independent variables measured seasonally at two sampling altitudes at 12 rivers of the massif. Using a logistic regression model we found that a permanence of water flow and lower water temperature were significant predictors of tadpole presence. Streams with mean summer temperature above 17.2 °C, at 300 m – 400 m above sea level, do not have tadpoles. Summer and autumn abstraction should be avoided, while a summer water temperature above an average of 17.2 °C is a threshold of potential concern for management authorities responsible for biodiversity conservation, threat mitigation efforts, and bulk-water supply and abstraction.Conservation implications: The Environmental Water Reserve has not been determined for streams of Table Mountain. The requirements of the Critically Endangered Table Mountain Ghost Frog (Heleophryne rosei) can be adopted as the minimum conditions to support this species and associated communities. Perennial flow, an average January water temperature of 17.2 °C or lower.

Asian carp spawning success: Predictions from a 3-D hydrodynamic model for a Laurentian Great Lake tributary

Asian carps are threatening to establish in the Great Lakes basin and the examination of factors leading to spawning success is vital for preventive efforts. Hydrodynamic modelling can determine if successful hatching of carp eggs can occur in a tributary, by predicting egg movement during a spawning event to see if hatching can occur before eggs settle. A 3-D hydrodynamic model, coupled with a Lagrangian particle tracker, was used to assess hatching rates of three Asian carp species (bighead, grass, and silver carps) in different temperature and flow scenarios in the east Don River, a potential spawning tributary to Lake Ontario. In-river hatching rates were highest in scenarios with warmer summer water temperatures (23–25 °C) and flow magnitudes of 15–35 m3/s, which occur at least once every year. Using a 3-D hydrodynamic model allowed the inclusion of low-velocity zones where eggs become trapped in lower flow scenarios, thereby reducing modelled hatching success. In-river hatching rates were significantly reduced when the spawning location was moved close to the mouth of the river, with no modelled hatching if spawning occurred in the lower 8 km of the Don River, indicating that preventing Asian carp movement upstream would viably reduce the chances of successfully spawning occurring in this tributary. The magnitude of reduction in spawning success caused by limiting Asian carp passage upstream can guide preventative strategies and the method of using a 3-D hydrodynamic model as a predictive tool could be applied in similar tributaries across the Great Lakes basin.

Oxidative stress biomarkers in the African sharptooth catfish, Clarias gariepinus, associated with infections by adult digeneans and water quality.

Parasites and environmental features could synergistically act as stressors to the health of their hosts. The objectives of this study were to evaluate the effect of: (i) water quality, host sex, size and body condition on adult digenean parasite infections; (ii) digenean infections and host sex and size on the oxidative stress biomarkers and body condition of hosts; and (iii) water quality on the oxidative stress biomarkers and body condition in Clarias gariepinus. Water quality variables were measured and C. gariepinus were collected each month for a year for examination of two intestinal digeneans, Masenia nkomatiensis and Glossidium pedatum, and determination of body condition and measurement of biomarkers in the host. The results indicated that the intensity of M. nkomatiensis was positively correlated with electrical conductivity and total dissolved solids. Prevalence of G. pedatum was negatively correlated with electrical conductivity, salinity and total dissolved solids. High summer water temperature was strongly associated with high digenean infections. There was no host body condition, sex or size bias for any of the parasite infection variables. Differences in the biomarker levels and body condition between uninfected fish and those infected with M. nkomatiensis or G. pedatum were insignificant indicating a low effect of the digenean parasites on oxidative stress biomarkers and body condition in the fish. However, total protein levels were positively associated with host size, and lipid peroxidation was negatively related to host body condition; total protein levels were also positively correlated with temperature and negatively correlated with dissolved oxygen. Host body condition was only negatively correlated with dissolved oxygen. Overall the trends observed in the data showed that the parasites have a negligible effect on oxidative stress in host fish and the trends observed for all variables (water quality, stress biomarkers, body condition and parasite infections) showed a strong seasonal pattern.

Diversity and ecological characteristic of algae and cyanobacteria of thermokarst lakes in Yakutia (northeastern Russia)

AbstractA total of 437 species (453 with infraspecific taxa) of algae and Cyanobacteria were identified in 2034 samples collected during the first research on nine thermokarst lakes in Yakutia carried out in 1986–1994 and 2001–2015. The richest algal flora was determined in Lake Aalah, represented by 241 taxa. Bacillariophyta species dominated in four lakes, whereas Chlorophyta and Cyanobacteria dominated in the others. The algal bioindication demonstrated preferences for benthic and plankticbenthic life, temperate temperature, low alkalinity, waters with moderate oxygenation, low to medium enrichment with chloride, low organic pollution, and mesotrophic state. Comparative floristic, CANOCO and JASP statistical methods divided the species and environmental variables into groups of lakes related to landscape terraces. Local landscape positions and high summer water temperatures may play a major role in the formation of algal flora. The index of algae taxa per area stabilized at about 70 species per km2. The highest polymorphism of algae floras, defined by the Subspecies/Species Index, was determined for the lakes of the Tungulunskaya terrace: Lake Ynakh, Lake Nal Tungulu and Lake Tungulu (1.041–1.058), and the average total flora was 1.036. Our results can help in monitoring and protecting the ecosystems of thermokarst lakes in Yakutia in the harsh climate environment of Northeastern Eurasia.

How do environmental factors affect the yield of European eel (Anguilla anguilla) in a restocked population?

Restocking of European eel (Anguilla anguilla) is a widespread practice throughout Europe. Conditions during restocking activities and mortality related to restocking practices have been discussed, however, factors affecting these restocked populations afterwards are mostly not considered. In this study we used a machine learning method followed by generalized linear model to analyze long time eel restocking, commercial fishery and environmental data from Lake Võrtsjärv, Estonia, to detect whether significant relationships exist within these data. It was found that environmental parameters can have an effect on the commercial eel yield both retrospectively and during the particular fishing year. Considering that 7-year old eel was the most common age group in commercial catch, we introduced a 7-year gap between eel restocking and yield to study the most important abiotic and biotic factors during the first year of eel restocking that have an effect on the yield. According to our results, cyanobacterial biomass and summer water temperature during the year of restocking had the strongest negative impact on the yield 7 years after, while the number of restocked individuals and copepod biomass had a positive effect. During particular fishing year, however, the yield was most notably positively affected by total phosphorous concentration, number of individuals restocked 7 years before and metazooplankton biomass in the lake.

Metabolic rates of Neomysis americana (Smith, 1873) (Mysida: Mysidae) from a temperate estuary vary in response to summer temperature and salinity conditions

AbstractThe mysid Neomysis americana (Smith, 1873) is native to shallow shelf waters and estuaries of the western Atlantic coast of North America. Despite the important role mysids such as N. americana play in estuarine ecosystems as both consumers and as prey for higher trophic levels, there is limited information on how metabolism influences their spatial ecology and habitat requirements. In tributaries of Chesapeake Bay, MD, USA, previous research has shown that summer water temperatures can approach the lethal upper tolerance limit for N. americana. We measured the per capita metabolic rate (µgO2 min–1) of N. americana from the upper Patuxent River near Benedict, MD, a tributary of Chesapeake Bay in the laboratory to evaluate the metabolic response to salinity and temperature conditions that mysids experience in natural habitats. Sex-specific and diel patterns in metabolic rate were quantified. Metabolic rates did not differ between night and day and there was no significant difference in metabolic rate between males and females, exclusive of gravid females. Metabolic rates were lowest in salinity treatments of 2 and 8 at 29 °C, and highest in the salinity 2 treatment at 22 °C. Only temperature had a statistically significant, albeit unexpected, effect. This study shows that the metabolic response of N. americana to temperature and salinity conditions is complex and plastic, and that metabolic rates can vary 3–4 fold within realistic summer temperature and salinity conditions. As environmental conditions continue to change, understanding metabolic response of mysids to realistic salinity and temperature conditions is necessary for understanding their distributions in temperate estuaries.

Benefit-cost analysis of water quality policy and criteria in the Delaware River

Abstract This research conducts a benefit-cost analysis of water policies to reach an optimal level of dissolved oxygen (DO) to meet year-round fishable water quality criteria in the Delaware River. A watershed pollutant load model is utilized to estimate marginal cost curves of water quality improvements to meet a more protective year-round fishable standard and annual benefits are defined to achieve future DO criteria in the Delaware River. The most cost-effective DO standard is 4.5 mg/L defined by the point where the marginal benefits of willingness to pay (WTP) for improved water quality equals the marginal costs of pollution reduction. This optimal criteria (4.5 mg/L) can be achieved at a cost of $150 million with benefits ranging from $250 to $700 million/year. While a future DO standard of 4.5 mg/L reflects an economically efficient level of water quality, this DO criteria is less protective than the level of 5–6 mg/L needed to protect anadromous fish such as the Atlantic sturgeon. The policy to reach a DO level of 6 mg/L (at 80% DO saturation) may be difficult to achieve at summer water temperatures that approach 30 °C in the Delaware River at Philadelphia.

A Study on the Characteristics of Summer Water Temperature Fluctuations by Spectral Analysis in Coast of Korea in 2016

A Study on the Characteristics of Summer Water Temperature Fluctuations by Spectral Analysis in Coast of Korea in 2016

The Importance of Offshore Exchange for Water Temperatures in Norwalk Harbor

The Norwalk Harbor is the estuarine portion of the Norwalk River, which connects to Long Island Sound. Like many embayments, this macrotidal harbor experiences higher summer water temperatures than waters farther offshore, which contribute to water quality problems. The summer season is characterized by surface heating, strong tides (as in all seasons), weak winds, and low river discharge. To determine the relative importance of exchange with offshore waters in regulating the harbor temperature, a control volume approach is used to make a summer temperature budget for the harbor based on observations. Time series of harbor temperature, surface heat flux, and Norwalk River inflow are constrained with measurements of water temperatures, atmospheric conditions, and river discharge. The impact of offshore exchange is inferred as the residual after the real temperature change in the harbor, and all other sources of temperature change are constrained. The analysis indicates that, in the summer, the impact of offshore exchange is comparable to the impact of the surface heat flux and far greater than the impact of the river. Consequently, the harbor is much cooler during summer than it would be if it was not connected to Long Island Sound. The methods applied here are applicable to any relatively small, semi-enclosed body of water and do not require the use of models or velocity observations. It is likely that many other embayments have an appreciable degree of thermal buffering via exchange with offshore waters.

Rheophilic Macrozoobenthos Communities in the Western Tien Shan

The regional diversity and characteristics of rheophilic macrozoobenthos communities in the western Tien Shan are described based on 370 original quantitative samples from lotic waters in the western Tien Shan (Kyrgyzstan). We have determined altitudinal differences in the composition and structure of the communities in three zones ranging from 1000 to 3700 m above sea level. Twenty-three types of revealed communities were assigned to the previously identified five classes: rhithral (hard-bottom substrates with a rapid flow), crenal (mosaic substrates of small springs and brooks), pelal (soft-bottom substrates), ripal (mosaic substrates of the water edge), and ephemeral (temporary biotopes). It is shown that the communities of the low mountains in Tien Shan are structurally similar to the communities of other low mountains in southern Palearctic regions (Caucasus and Balkans), the communities of the middle mountains are similar to those of the low Arctic (Kola Peninsula and Yamal), and the communities of the high mountains are similar to those of the high Arctic (Svalbard). Thus, the effects of altitudinal and latitudinal zonation on mountain lotic communities in the Palearctic are generally similar and mainly mediated by summer water temperature.

Tendencies of Invasion of Alien Zoobenthic Species into the Black Sea

The published data on alien species in zoobenthos of the Black Sea are generalized for the last hundred years of research. The list of alien species is prepared; 61 zoobenthic alien species are registered. The long-term variability of the invasions of alien zoobenthic species into the sea is analyzed. The intensification of invasion of the zoobenthic species into the Black Sea occurs during the period of climatic changes in the region. A statistically significant relationship is revealed between the interdecadal variability of the number of alien species and the deviations of the summer water temperature from the average interannual (100 years) one.

Absence of recovery in a degraded eelgrass (Zostera Marina) bed in Nova Scotia, Canada: Results from a transplant study

By the early 2000s, the invasion of the European green crab (Carcinus maenas) had caused a severe decline of eelgrass (Zostera marina) beds in eastern Canada. The formerly lush eelgrass bed in Benoit Cove, Nova Scotia, was extirpated by 2009 and has subsequently failed to recover. The objective of our study was to establish if Benoit Cove (BC) has reached a new equilibrium in which eelgrass cannot recolonize. From July 3 - August 29, 2018, we transplanted eelgrass using frames and monitored eelgrass growth and survival relative to the nearby donor (control) site in Tracadie West Arm (TWA) that had an extensive eelgrass meadow with over 95% cover. Transplant survival was 91.6% and 15.4% for TWA and BC, respectively (P < 0.001). Above-ground growth declined at both sites, and could be associated with high summer water temperatures and/or extreme epiphytism. Sediments at both sites had high silt composition (> 28%), and the absence of a macrophyte canopy lead to increased light attenuation in BC in moderate wind and tidal currents. The low density of green crabs in both BC and TWA (0.01 m-2 and 0.08 m-2, respectively), and the apparently healthy eelgrass bed in TWA, suggest that green crabs are not having a negative effect on eelgrass in this system and are not responsible for the lack of recolonization of eelgrass in BC.Keywords: Atlantic Canada; eelgrass bed; European green crab; transplant; Zostera marina

Aquatic and riparian ecosystem recovery from debris flows in two western Washington streams, USA.

An exceptionally powerful storm struck southwestern Washington in December 2007 causing large debris flows in two adjacent streams. The two affected streams had been studied prior to the storm, providing a rare opportunity to examine ecosystem recovery. We monitored the streams and their riparian zones for six years after the disturbances to determine whether recovery rates of biota, physical habitat, and water temperature differed, and if so, what factors affected resilience. Along both streams, the debris flows removed wide swaths of soil, rock, and coniferous riparian forests, widening the active channel and increasing solar exposure and summer water temperatures. Initially depauperate of vegetation, after four years red alder trees dominated the riparian plant communities. The warmer water, greater solar radiation, and unstable substrates likely contributed to variable benthic insect and tailed frog tadpole densities over time, although benthic insect communities became more similar after three years. The debris flows also decreased channel slopes and removed channel step barriers such that cutthroat trout were able to rapidly occupy habitats far upstream, but sculpins were slower to recolonize and both fish species exhibited some differences in recovery between the two streams. Crayfish were severely impacted by the debris flows; this may be due to attributes of their life history and the timing of the flows. Overall, we found that recolonizing aquatic species exhibited varying levels of resilience and recovery after the disturbances being related to the influence of physical habitat conditions, species dispersal ability, and the presence of nearby source populations.

Variability of hydrochemical parameters of small boreal lakes under natural and anthropogenic factors (case study of NW Russia)

Small lakes of the boreal zone are highly sensitive indicators of both global environmental change and local anthropogenic pressure. This work presents the results of multidisciplinary study of three small, seasonally stratified lakes of NW Russia, conducted since 2002 to the present time. These lakes were subjected to various degree of impact by rural population and agricultural activity since the beginning of twentieth century but the population and anthropogenic pressure have decreased since 1990s. To monitor the recovering of these lakes from human impact and to relate the evolution of their hydrochemical parameters to short-term weather events and global climatic trend, we measured the lake water temperature and chemical composition (carbon, macro- and micronutrients, trace elements) in summer and winter over full depth of the water column. The pH and concentration of DIC, SO4 and H2S decreased over past decade. Concentrations of Si and nitrite increased over past 15 years, probably linked to progressive replacement of diatoms by cyanobacteria. We also recorded an increase in concentration of Cl and major cations in all lakes, likely linked to increasing connection to groundwater reservoirs. Some trace elements (Fe, Mn, Al, Zn, As, Pb) can serve as suitable indicators of on-going natural processes controlling lake response to external factors. Unlike widely reported global trend of DOC and Fe concentration increase in boreal surface waters of Europe and Northern America, such trend was not discernable in studied Fe-rich humic lakes. We conclude on the necessity of complex, multidisciplinary studies of small humic lakes in the boreal zone, because these “model” lakes can serve as important proxies of on-going environmental changes in highly abundant aquatic ecosystems of poorly characterized regions of NW Russia.

Summer stream temperature changes following forest harvest in the headwaters of the Trask River watershed, Oregon Coast Range

AbstractThe Trask River Watershed Study in the northern Oregon Coast Range was designed to examine physical, chemical, and biological effects of contemporary forest management practices on aquatic ecosystems. We measured stream temperature for 11 summers in 15 small watersheds, eight of which were harvested in 2012. Three riparian buffer treatments, which varied by landowner, were implemented. Using half‐hourly data, we characterized summer water temperature distributions with five percentiles: 5th, 25th, 50th, 75th, and 95th. Each percentile was analysed as a separate response variable using a linear mixed model. After harvest, streams without overstory buffer requirements showed shifts in all the percentiles of the temperature distribution; the largest increase (3.6°C) occurred at the 95th percentile. Sites with narrow riparian buffers showed little to no change. We also calculated changes in duration of thermal exposure above 15°C and 16°C for two species of native stream amphibians; these temperatures occurred 4.7% and 1.3% of the time postharvest in the sites clearcut with no buffer. Analysis of distributions of summer temperatures preharvest and postharvest enabled us to more fully characterize site‐to‐site variability and responses to forest management.

Some Approaches to the Assessment of the Ecological State of Different-Type Reservoirs Based on the Relationship among their Main Hydrochemical Parameters

An attempt has been made to assess the status and trends of ecosystems of differenttype reservoirs in Europe and Asia (the Saratov and Volgograd ones, closing the Volga cascade, and the Iriklinsky one, which is the largest on the Ural river) on the basis of the relationship of basic hydrochemical parameters. The ecological status of water bodies was considered from the position of the stability of their ecosystems, which was evaluated using some statistical approaches based on the data of long-term monitoring. The proportion of variability of the main components, the index of plasticity (reliability) corresponding to the average module of the correlation coefficients of hydrochemical parameters were calculated. The desirability function method for qualitative assessment of aquatic ecosystems, characterized by a large number of hydrochemical parameters, was applied. This method allowed minimizing a large amount of information and overcoming the dimension problem. The results of the application of the calculated statistical indices allow us to consider the volume of water flow and summer water temperature as the main factors affecting the content of basic hydrochemical ingredients in the Volgograd and Iriklin reservoirs. The hydrochemical regime of the Saratov reservoir, due to its high flow rate, is determined mainly by the waters coming from the Kuibyshev storage reservoir, and therefore such dependencies were not established. During the study period, the entropy index in the Volga reservoirs fluctuated at the same level, but significantly increased in the Iriklinsky one. The highest values of plasticity are characteristic for the Iriklinsky reservoir, which has the greatest spatial and seasonal heterogeneity of its aquatic environment. During the study period, there have been trends of increasing plasticity in the Saratov reservoir and decreasing in the Iriklinsky one. A decrease in the desirability function indicates some destabilization of their ecosystems.

Occurrence of a temperate coastal flatfish, the marbled flounder Pseudopleuronectes yokohamae, at high water temperatures in a shallow bay in summer detected by acoustic telemetry

The marbled flounder Pseudopleuronectes yokohamae, a flatfish found in temperate coastal waters, is an important commercial species in the northwestern Pacific Ocean, but little is known of its distribution and movement under high water temperatures in summer. We recorded the distribution and movement of marbled flounder in shallow water in Tokyo Bay with acoustic telemetry. Seventeen wild flounder tagged with acoustic transmitters were tracked/monitored by active tracking using a research vessel and sporadic monitoring using fishing gear and a fishing boat. We located six individuals in shallow (< 30 m) water at temperatures of 19–23 °C and dissolved oxygen (DO) concentrations of 3–5 ml/l in Tokyo Bay, while bottom water temperatures and DO concentrations ranged from 19 to 24 °C and 0–7 ml/l, respectively. Our results indicated that at least 35% of the flounder remained in warm, shallow waters in summer. Multiple monitoring methods and the assistance of fishermen helped to overcome the difficulties of working in a crowded bay and increased our recovery rate of the tagged flounder.

Biogeographic classification of streams using fish community– and trait–environment relationships

AbstractAimPresent a hybrid biogeographic and environmentally constrained clustering approach to classify ~853,000 stream reaches in the eastern United States. Examine the frequency of stream typologies in the landscape relative to anthropogenic stressors to identify potential stream conservation needs.LocationEastern United States.MethodsFish communities at 956 least‐disturbed sampling reaches were characterized using taxonomic and functional composition of native species. Environmental variables summarized within stream reaches included stream discharge, channel gradient, hydrologic regime, summer water temperature and boundaries of freshwater ecoregions. Multivariate regression trees were used to relate environmental variables to fish communities while simultaneously developing taxa‐ and trait‐specific biogeographic classifications. We then overlaid stream classifications with indices of anthropogenic disturbances to evaluate rarity and risk of complete loss of natural representation of stream types.ResultsTaxonomically based classes represented a combination of ecoregional boundaries and environmental gradients, whereas temperature gradients were most important in differentiating functional composition. An optimal taxonomy‐based classification contained 13 classes and explained 26.4% of community variation, and the optimal trait‐based classification contained 6 classes, explaining 25.2% of community variation. Overlaying class maps with an anthropogenic disturbance index revealed substantial variation in the severity of degradation among classes relative to their abundance in the landscape, especially rare classes (i.e., large rivers and cold headwater systems).Main conclusionsWe demonstrate the value of integrating local, regional and historical biogeographic factors with taxonomic and functional characteristics of freshwater biota to classify ecosystems based on mechanistic biota–environment relationships. This approach is important to addressing the challenge of developing stream classifications that reconcile the environmental drivers of community trait composition with the constraints of biogeographic regionality at large spatial scales. Furthermore, the spatially explicit and high‐resolution maps disseminated here can uniquely inform management decisions regarding anthropogenic threats to the biodiverse freshwaters of the eastern United States.