Lakes In England Research Articles

Cladoceran remains reveal presence of a keystone size-selective planktivore

We tested the use of cladoceran remains as a proxy for the presence and life history type of alewife (Alosa pseudoharengus) from pre-colonial times to present in a group of coastal lakes in southern New England. Alewife are a keystone predator that structure the zooplankton community through strong predation on large-bodied zooplankton species, which releases small zooplankton species, such as Bosmina spp., from competition and predation pressure. In southern New England there are lakes without alewife, lakes with anadromous alewife that only reside in lakes during the summer, and lakes with landlocked alewife that reside in lakes year-round. The entire zooplankton commu- nity of these lakes is structured differently based on the presence and type of alewife they contain. We examined differences in the morphology of Bosmina spp. from sediment core samples and contemporary zooplankton samples between lakes with different types of alewife. We found that there were significant differences in the morphology of Bosmina spp. between lakes with and without alewife. We also used discriminant analysis on the morphology of Bosmina spp. to classify lakes in terms of alewife presence and alewife type. We found that the morphology of Bosmina spp. can serve as a useful proxy for detecting the presence, but not the life history type of alewife from paleoecological and contemporary inferences.

Trophic status, ecological condition, and cyanobacteria risk of New England lakes and ponds based on aircraft remote sensing

Aircraft remote sensing of freshwater ecosystems offers federal and state monitoring agencies an ability to meet their assessment requirements by rapidly acquiring information on ecosystem responses to environmental change for water bodies that are below the resolution of space-based platforms. During this study, hyperspectral data were collected over a two-day period from glacial lakes, ponds, and man-made reservoirs in New Hampshire, Massachusetts, Connecticut, and Rhode Island. These lakes ranged from five to greater than 1600 hectares and oligotrophic-mesotrophic to eutrophic and hypereutrophic conditions. Water samples were collected by several New England state agencies coincident with the airborne remote-sensing flights to provide ground reference data for algorithm development and testing. Using an inverse modeling approach remotely sensed reflectances from the near-infrared to red portion of the spectrum were used to develop an empirical model to estimate chlorophyll a concentrations. The accuracy of the algorithm was assessed from the RSM error of predicted and measured chlorophyll values for all lakes sampled. Results showed a strong statistical relationship between measured and predicted values. The predicted chlorophyll concentrations were used to assess the biological condition, trophic status, and recreational risk to human health for the New England lakes and ponds surveyed.

MERGANSER: An Empirical Model To Predict Fish and Loon Mercury in New England Lakes

MERGANSER (MERcury Geo-spatial AssessmeNtS for the New England Region) is an empirical least-squares multiple regression model using mercury (Hg) deposition and readily obtainable lake and watershed features to predict fish (fillet) and common loon (blood) Hg in New England lakes. We modeled lakes larger than 8 ha (4404 lakes), using 3470 fish (12 species) and 253 loon Hg concentrations from 420 lakes. MERGANSER predictor variables included Hg deposition, watershed alkalinity, percent wetlands, percent forest canopy, percent agriculture, drainage area, population density, mean annual air temperature, and watershed slope. The model returns fish or loon Hg for user-entered species and fish length. MERGANSER explained 63% of the variance in fish and loon Hg concentrations. MERGANSER predicted that 32-cm smallmouth bass had a median Hg concentration of 0.53 μg g(-1) (root-mean-square error 0.27 μg g(-1)) and exceeded EPA's recommended fish Hg criterion of 0.3 μg g(-1) in 90% of New England lakes. Common loon had a median Hg concentration of 1.07 μg g(-1) and was in the moderate or higher risk category of >1 μg g(-1) Hg in 58% of New England lakes. MERGANSER can be applied to target fish advisories to specific unmonitored lakes, and for scenario evaluation, such as the effect of changes in Hg deposition, land use, or warmer climate on fish and loon mercury.

Assessing element-specific patterns of bioaccumulation across New England lakes

Little is known about differences among trace elements in patterns of bioaccumulation in freshwater food webs. Our goal was to identify patterns in bioaccumulation of different elements that are large and consistent enough to discern despite variation across lakes. We measured methylmercury (MeHg) and trace element (As, Cd, Hg, Pb, and Zn) concentrations in food web components of seven New England lakes on 3–5 dates per lake, and contrasted patterns of bioaccumulation across lakes, metals and seasons. In each lake, trace element concentrations were compared across trophic levels, including three size fractions of zooplankton, planktivorous fish, and piscivorous fish. The trophic position of each food web component was estimated from N isotope analysis. Trace element concentrations varied widely among taxa, lakes and sampling dates. Yet, we identified four consistent patterns of bioaccumulation that were consistent across lakes: (1) MeHg concentration increased (i.e., was biomagnified) and Pb concentration decreased (i.e., was biodiminished) with increased trophic position. (2) Zinc concentration (as with MeHg) was higher in fish than in zooplankton, but overall variation in Zn concentration (unlike MeHg) was low. (3) Arsenic and Cd concentrations (as with Pb) were lower in fish than in zooplankton, but (unlike Pb) were not significantly correlated with trophic position within zooplankton or fish groups. (4) Average summer concentrations of As, Pb, Hg, and MeHg in zooplankton significantly predicted their concentrations in either planktivorous or piscivorous fish. Our secondary goal was to review sampling approaches in forty-five published studies to determine the extent to which current sampling programs facilitate cross-lake and cross-study comparisons of bioaccumulation. We found that studies include different components of the food web and sample too infrequently to enable strong cross-lake and cross-study comparisons. We discuss sampling strategies that would improve our capacity to identify consistent patterns of bioaccumulation and drivers of elevated trace element concentrations under naturally high levels of variability.

Development of a classification and decision-support tool for assessing lake hydromorphology

Bridging the gap between policy aspirations and the ability of regulators to deliver robust evidence-based tools within affordable and realistic time-scales presents major challenges to the science community. Lake-MImAS (Morphological Impact Assessment System) is a hydromorphological classification and decision-support tool adaptable to any setting, developed in response to the EC Water Framework Directive (WFD) requirement to classify all surface waters in the European Union and achieve at least good ecological status by 2015. Lake-MImAS provides a transparent and consistent risk-assessment framework to assess the impact of hydromorphological pressures on ecologically relevant lake features and associated processes. Underpinned by expert-judgement, the tool quantifies lost ‘system capacity’ (%) relative to pristine, or un-impacted condition and does so on a type-specific basis. Morphological condition limits (MCLs) separate ‘lost capacity’ into five condition classes ranging from near natural to severely altered. Near natural (<5% capacity loss) corresponds directly with high ecological status of the WFD and provides the basis to define reference conditions. The calibrated tool was tested against independent judgement made by expert practitioners from UK environment and conservation agencies. The same condition class was assigned in 84% of Scottish lochs (n=40), in 58% of lakes in England and Wales (n=28) and in 57% of loughs in Northern Ireland (n=27). The overall agreement was 68% and 98% of all comparisons lay within one condition class. In most cases where different classes were assigned the explanation lay in local experts underestimating the extent of water level regulation. Whilst further work is required to strengthen the evidence base linking hydromorphological alteration and ecological response, Lake-MImAS provides the foundation for a pragmatic risk-assessment scheme to support WFD classification and related regulatory activity. The modular nature of the tool means it adaptive to new locations, lake type and pressure combinations and it has wider applications including physical condition monitoring for conservation sites, impact assessment arising from new developments and supporting remediation programmes.

A Comparison of Macroinvertebrate and Epiphyte Density and Diversity on Native and Exotic Complex Macrophytes in Three Vermont Lakes

Abstract Invasion of New England lakes by exotic macrophytes can alter trophic interactions if the invaders host macroinvertebrate and epiphyte communities different from those of the native species they replace. Macroinvertebrate density and diversity appears to increase with macrophyte complexity and epiphytic algae colonization, which are also positively correlated. Because of this confounding effect, we investigated native and exotic macrophyte species of similar complexity in order to answer the question: Does the exotic macrophyte Myriophyllum spicatum have lower epiphyte density and richness that results in lower macroinvertebrate density and diversity than those found on a native species of similar complexity? Using independent-sample t-tests, we investigated this question in mixed macrophyte stands of three Vermont lakes. Holding complexity constant, macroinvertebrate density and diversity was positively related with epiphyte density and richness (r 2 = 0.17 and 0.13, respectively). Generally, M....

Interpopulation variation in a fish predator drives evolutionary divergence in prey in lakes

Ecological factors are known to cause evolutionary diversification. Recent work has shown that evolution in strongly interacting predator species has reciprocal impacts on ecosystems. These divergent impacts of predators may alter the selective landscape and cause the evolution of prey. Yet, this link between intraspecific variation and evolution is unexplored. We compared the life history of a species of zooplankton (Daphnia ambigua) from lakes in New England in which the dominant planktivorous predator, the alewife (Alosa pseudoharengus), differs in feeding traits and migratory behaviour. Anadromous alewife (seasonal migrants) exhibit larger gapes, gill-raker spacing and target larger prey than landlocked alewife (year-round freshwater resident). In 'anadromous' lakes, Daphnia are abundant in the spring but extirpated by alewife predation in summer. Daphnia are rare year-round in 'landlocked' lakes. We show that Daphnia from lakes with anadromous alewife grew faster, matured earlier but at the same size and produced more offspring than Daphnia from lakes with landlocked or no alewife across multiple temperature and resource treatments. Our results are inconsistent with a response to size-selective predation but are better explained as an adaptation to colder temperatures and shorter periods of development (countergradient variation) mediated by seasonal alewife predation.

GPR characterization of a lacustrine UXO site

We used [Formula: see text] ground-penetrating-radar (GPR) reflection profiles to determine if high-explosive (HE) depth bombs were possibly detonated within a small New England lake formerly used as a bombing range, as well as the depths and distribution of inert and possibly unexploded ordnance (UXO) within the subbottom sediments. Maximum water depth was [Formula: see text]. The primary munitions were unarmed practice bombs, but terrestrial fragments from HE depth bombs led us to seek stratigraphic obliteration and distortion as evidence of their use. The low water conductivity and quartz-rich sediments provided more than [Formula: see text] of subbottom penetration beneath slope and shelf sediments. The high permittivities of the water and subbottom sediments provided good antenna directivity, excellent 2D migrations, multicentimeter vertical resolution, and a unique pulse waveform signature for metal objects. Our line profiles revealed hundreds of subbottom diffractions, which implied an areal distribution of thou-sands of suspicious objects. Most lay beneath the central basin, but many resided beneath the slopes and shelves as well. Supplementary profiles of a nearby pristine lake and of controlled munitions, a side-scan sonar bottom survey, and time-domain reflectometry dielectric measurements of sediment samples corroborated our findings of natural stratigraphy, a unique metallic diffraction phase signature, the existence of many nonmetallic objects including logs, and subbottom relative permittivities ranging from 28 to 76. The intact natural lacustrine strata, including deltaic foresets and bottom sets, faults, and conformable and unconformable horizons, suggest that live bombs likely did not detonate in the lake. The only stratigraphic disturbances we found were apparent perforations beneath about [Formula: see text] of water, within which diffractions of metallic origin originated. The dielectric results and the prominent slope strata over the deepest horizons led us to conclude that the exceptional subbottom penetration existed under predominantly sandy sediments.

The dawn of green: Manchester, Thirlmere, and modern environmentalism

Located in the heart of England's Lake District, the placid waters of Thirlmere seem to be the embodiment of pastoral beauty. But under their calm surface lurks the legacy of a nineteenth-century conflict that pitted industrial progress against natural conservation - and helped launch the environmental movement as we know it. Purchased by the city of Manchester in the 1870s, Thirlmere was dammed and converted into a reservoir, its water piped one hundred miles south to the burgeoning industrial city and its workforce. This feat of civil engineering - and of natural resource diversion - inspired one of the first environmental struggles of modern times. The Dawn of Green re-creates the battle for Thirlmere and the clashes between conservationists who wished to preserve the lake and developers eager to supply the needs of a growing urban population. Bringing to vivid life the colorful and strong-minded characters who populated both sides of the debate, noted historian Harriet Ritvo revisits notions of the natural promulgated by romantic poets, recreationists, resource managers, and industrial developers to establish Thirlmere as the template for subsequent - and continuing - environmental struggles.

Early-Holocene temperature variability inferred from chironomid assemblages at Hawes Water, northwest England

This paper presents the first high-resolution chironomid-inferred mean July air temperature (C-IT) reconstruction for the early Holocene from England. The reconstruction is based on a core recovered from a terrestrialised carbonate bench at Hawes Water, a small hard-water lake in northwest England. The record shows that temperatures rose rapidly after the Younger Dryas with temperatures reaching 14.0°C at the beginning of the Holocene. Over millennial timescales, the temperature record points to a slight rise in temperatures towards the top of the sequence at around 8000 years before the year 2000 (b2k). The trend is punctuated by a series of cool oscillations (at 11 200, 11 400, 10 700, 10 400, 9300 and 8300 b2k) and by a short period (11 300 to 10 250 b2k) when temperatures were considerably warmer (up to 14.9°C). The five cool oscillations coincide with temperature reversals found elsewhere in the North Atlantic region and in the Greenland ice core records. These cool events correlate well with both meltwater fluxes from the Laurentide and Scandinavian ice sheets and periods of low solar activity. Two of these oscillations (at 9300 and 8300 b2k) vary significantly from the early-Holocene mean. C-IT shift rapidly during both these events and temperatures fall ~1.6°C below the early-Holocene mean trend for ~ 50—60 years. The results presented here provide an insight into the instability of the early-Holocene climate in the British Isles and demonstrate the sensitivity of chironomids to rapid climatic events during the early Holocene.

A model‐based assessment of non‐compliance of phosphorus standards for lakes in England and Wales

High phosphorus concentrations causing eutrophication will prevent many lakes in England and Wales from reaching good ecological status by 2015 according to the EC Water Framework Directive (WFD). The aim of this study was to estimate the percentage of lakes in England and Wales that are likely to fail recently agreed WFD phosphorus standards. As measured lake phosphorus concentrations are only available for a small number of lakes a model‐based approach was adopted. This involved estimating phosphorus loads from a wide range of sources including agricultural loads, sewage effluents, septic tanks, diffuse urban sources, atmospheric deposition, groundwater and bank erosion. Lake phosphorus concentrations were predicted using the Vollenweider model, and the model framework was satisfactorily tested against available observed lake concentration data. Applying the model to all lakes in England and Wales greater than 1 ha, it was estimated that under current conditions, roughly two thirds of the lakes would fail good ecological status with respect to phosphorus. According to our estimates, agricultural phosphorus loads represent the dominant source for the majority of catchments, but diffuse urban runoff also is important in many lakes and sewage effluents are the most frequent dominant source for lake catchments greater than 100 km2. Required reductions of phosphorus loads to increase the number of lakes achieving good ecological status and potential delays because of internal loading and biological resistances are briefly discussed.

The effects of littoral zone vegetation on turbulent mixing in lakes

Micro-scale thermal profile data were acquired in four lakes in northwest England and southeast Australia that ranged from a small, sheltered pond with a surface area of about 1 ha to more open lakes with surface areas of several square kilometres. These lakes provided a range of topographic and climatic contexts, basin morphologies and dominant macrophyte species. The data were acquired using two SCAMP profilers, one deployed in the open water and the other mounted on a field traverse deployed within the vegetated littoral zone. From these profile data, turbulence parameters were calculated. The results show the variation in the influence of vegetation on turbulence in the four lakes, which depends on the combination of wind stress, solar radiative forcing and macrophyte mechanical properties. In the sheltered pond, the vegetation alters the light climate within the water, thus reducing stratification and allowing weak, thermally-driven mixing. In the larger lakes, however, the primary action of the vegetation is to prevent surface-generated TKE from penetrating the water column, although this effect becomes less important as the plant separation increases. A simple mechanistic model, calibrated against the field data, suggests that the macrophyte mechanical properties are most important in determining the turbulent kinetic energy (TKE) profile. Increasing the number of turbulence-generating plants reduces the transport of surface-generated TKE into the deeper water, consistent with the field observations. The model suggests that solar forcing, as measured by the temperature gradient between the surface and bottom waters, is of less importance since the TKE profile is similar in runs with different gradients. Perhaps most surprisingly, the value of the surface-wind stress used in the model is not important, within the limitations of the model, as it does not change the TKE profile, except in a thin surface layer.

Lead Objects Ingested by Common Loons in New England

Abstract Necropsies of Gavia immer (Common Loon) recovered lead and non-lead foreign objects from gastrointestinal tracts. Carcasses collected between 1987 and 2000 reveal that a great deal of loon mortality on lakes in New England is attributable to ingestion of lead objects. In this study, 522 carcasses were examined to inspect the types, sizes, and masses of 222 objects responsible for lead toxicosis. Most ingested lead objects were less than 2.5 cm long and weighed less than 25 g. Information on objects ingested by loons may help in development of non-toxic alternatives.

Regional consistency in Lateglacial chironomid-inferred temperatures from five sites in north-west England

High resolution Lateglacial ice-core records from Greenland show both millennial and centennial-scale change and have been used as a benchmark for Lateglacial climatic stratigraphy throughout the North Atlantic region and beyond. In this study we assess the local reflection in north-west Europe of climatic events recognised in ice cores and identify differences in the climate signature between Greenland, UK and sites in continental Europe. This study uses chironomid-inferred temperature analysis and loss-on-ignition data from five carbonate lakes in north-west England to determine the pattern of Lateglacial climatic change and demonstrates the reproducibility of chironomid-inferred temperature reconstructions both within a catchment and from sites within a small area. At both millennial and centennial scales, our results show statistical similarities between sites, giving a clear regional signal. Chironomid assemblages pick out the rapid shifts at the major event boundaries at all sites and indicate temperatures of between 12 and 13 °C for the region at the beginning of Greenland Interstadial 1, a rapid fall of around 4 °C into the Younger Dryas and a rise of around 5 °C in the Early Holocene. At a finer scale, four centennial cooling events are identified within the interstadial, together with an oscillation in the Early Holocene which we tentatively identify as the pre-Boreal event. The records were analysed statistically using redundancy analysis and sequence-slotting techniques. Differences in the impact of individual climatic events, demonstrate that subtle changes in the chironomid-inferred temperatures reflect the local geographical setting and morphology of the lakes; with more marked impact registered in higher altitude and more wind-exposed sites. Whilst the overall pattern of Lateglacial climate can be recognised from Greenland to central Europe, important regional differences, that can be attributed to marine influence and, perhaps, changes in atmospheric circulation, are beginning to emerge.

Ecological variation within Sellaphora species complexes (Bacillariophyceae): specialists or generalists?

The genus Sellaphora has become a model system for studies of the species concept, speciation and automated identification in diatoms. Three species, S. pupula, S. bacillum and S. laevissima, have proved to be complexes containing several or many species, which are difficult to distinguish morphologically but which are genetically differentiated and (where tested) reproductively isolated. Until now, however, there has been little information about the ecology of the species within this complex, except in relation to parasite sensitivity. In order to test whether semi- and pseudo-cryptic Sellaphora species are ecologically differentiated with respect to trophic status, we used tools recently developed in the UK in response to the EU Water Framework Directive (WFD). Diatom samples from three substrata (plants, rocks, sediment) were taken from 22 lakes in Scotland and England, covering a gradient from oligotrophic mountain lakes to eutrophic lowland ponds. The epilithic and epiphytic diatom assemblages were used to evaluate lake trophic status according to the UK WFD assessment system and showed that there was a strong environmental gradient in the dataset. Sellaphora species occurred in the sediment-derived epipelon and their distributions were analysed in relation to the trophic gradient. A total of 28 Sellaphora phenodemes (putative species) were found, and some of them differed in their environmental demands. Two groups were distinguished: (1) a group indicating rather oligotrophic conditions and containing several demes with linear valves and subcapitate or capitate poles (referred to here as S. [pupula] cap-A, cap-B and cap-C and (2) a group occurring in eutrophic lakes and containing the recently described species S. blackfordensis, S. capitata and S. obesa, as well as S. [pupula] Φ ‘small lanceolate’. The data obtained are also discussed with respect to Finlay’s hypothesis on microalgal cosmopolitanism.

Women in Colour: Perceptions of Professionalism in Natural Dyeing during the Arts And Crafts Period

This article investigates women's dye practice at a time when natural dyes were deemed obsolete, or when created by men working from an artisanal studio, transformed into idealized labour more consistent with the ideals of the Arts and Crafts Movement. The objective of this article is to assess the extent to which gender plays a role in the historical and contemporary determination of the aesthetic, cultural, and social value of natural dyeing. Another goal is to move away from the term 'craft work' with its acquired pejorative context and locate dyeing within 'artisanal practice' as an occupational choice. Current studies on women's participation in the Arts and Crafts Movement raise questions as to the distinction between amateur and professional status among practitioners in many media. The only dyer deemed to be 'professional' was William Morris; yet in north-west Ireland, the Scottish Highlands, and England's Lake District, female dyers contemporary with Morris also made important contributions. That their production of colour originated from the separate sphere of home need not mitigate against professional status nor historical value, but there is a lingering perception that men such as Morris possessed inherently superior abilities. The focus of this article is also to analyze the mythology of natural dyeing which has limited the opportunity to recognize female dyers whose practice aligned with the utopian ideals of the Arts and Crafts Movement. Three examples are discussed here against a brief summary of centuries of women's involvement in the business and trade of dyeing. The Arts and Crafts dyers discussed in this paper are also compared to Morris. Women's abilities as colourists were as worthy of professional designation as were those same skills when they emanated from men who comprised the Movement's elite.

Case studies on eradicating the Asiatic cyprinid Pseudorasbora parva from fishing lakes in England to prevent their riverine dispersal

Abstract The topmouth gudgeon Pseudorasbora parva has proved to be a highly invasive pest fish species in mainland Europe following introduction from Asia, and was first recorded in the wild in the UK in 1996. Distribution has increased markedly since 2002, with recordings now from 32 sites, the majority being lakes. In infested UK lakes, populations establish rapidly and become dominant in the fish community (often &gt;97% by number); densities to over 60 m−2 have been recorded, with the majority of individuals &lt;70 mm. The species also hosts a novel pathogen not previously recorded in the UK. It has, therefore, been identified as a significant concern to native fish communities and deserving of an appropriate response by regulatory authorities. Where populations have been detected in lakes with connection to river catchments, actions have been taken to prevent riverine dispersal. Control measures are put in place, and eradication programmes designed and initiated. This paper details case studies on three completed eradication operations, two that utilized the piscicide rotenone, the other, de‐watering and disinfection. Each case study has, so far, been successful in eradicating the topmouth gudgeon population and has resulted in approximately 280 km of river length being protected from their dispersal. Application of rotenone was the most cost‐effective eradication method at approximately £2 per m2 of water area treated. These case studies demonstrate that riverine dispersal of invasive fish from infested connected lakes can be prevented by eradication. Outputs can be used to develop a strategy to manage the increasing distribution of topmouth gudgeon—and other invasive, pest fish—in the UK. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Anthropogenically Driven Changes in Chloride Complicate Interpretation of Base Cation Trends in Lakes Recovering from Acidic Deposition

Declines in Ca and Mg in low ANC lakes recovering from acidic deposition are widespread across the northern hemisphere. We report overall increases between 1984 and 2004 in the concentrations of Ca + Mg and Cl in lakes representing the statistical population of nearly 4000 low ANC lakes in the northeast U.S. Increases in Cl occurred in nearly all lakes in urbanized southern New England, but only 18% of lakes in more remote Maine had Cl increases. This spatial pattern implicates road salt application as the major source of the increased Cl salts. Among the 48% of the lake population classified as salt-affected, the median changes in Cl (+133 microeq/L) and Ca + Mg (+47 microeq/ L) were large and positive in direction over the 20 years. However, in the unaffected lakes, Cl remained stable and Ca + Mg decreased (-3 microeq/L), consistent with reported long-term trends in base cations of acid-sensitive lakes. This discrepancy between the Cl groups suggests that changes in ion exchange processes in salt-affected watersheds have altered the geochemical cycling of Ca and Mg. One policy-relevant implication is that waters influenced by Cl salts complicate regional assessments of surface water recovery from "acid rain" related to the passage of the Clean Air Act.

Water quality characteristics of two reservoir lakes in eastern Connecticut, USA

AbstractThe Mansfield Hollow Lake (MHL) and Willimantic Reservoir (WR) are two reservoirs located in eastern Connecticut in the north‐eastern USA. The MHL was constructed by the US Army Corps of Engineers in 1952, being primarily fed by the Fenton, Mount Hope and Natchaug Rivers. The WR lies downstream from the Mansfield Hollow Dam. The physical and chemical characteristics of MHL, WR, and the three streams discharging into them were intensively evaluated during four sampling quarters in 2001 and 2002. This study focused on possible sources of eutrophication, and occurrence of trace amounts of selected priority pollutants, in the sediments and waters of MHL and WR. Analytical results for total dissolved nitrogen and phosphorus and chlorophyll‐a indicated that, in terms of eutrophication status, the waterbodies can be classified as mesotrophic. Comparison of the analytical results in this study to historical limnological data reported for lakes in southern New England and eastern Connecticut indicates that the median levels of total nitrogen, total phosphorus, dissolved inorganic carbon, calcium, magnesium, and iron measured in this study were higher than previously reported median values.

Comparison of 15 evaporation methods applied to a small mountain lake in the northeastern USA

Summary Few detailed evaporation studies exist for small lakes or reservoirs in mountainous settings. A detailed evaporation study was conducted at Mirror Lake, a 0.15 km2 lake in New Hampshire, northeastern USA, as part of a long-term investigation of lake hydrology. Evaporation was determined using 14 alternate evaporation methods during six open-water seasons and compared with values from the Bowen-ratio energy-budget (BREB) method, considered the standard. Values from the Priestley–Taylor, deBruin–Keijman, and Penman methods compared most favorably with BREB-determined values. Differences from BREB values averaged 0.19, 0.27, and 0.20 mm d−1, respectively, and results were within 20% of BREB values during more than 90% of the 37 monthly comparison periods. All three methods require measurement of net radiation, air temperature, change in heat stored in the lake, and vapor pressure, making them relatively data intensive. Several of the methods had substantial bias when compared with BREB values and were subsequently modified to eliminate bias. Methods that rely only on measurement of air temperature, or air temperature and solar radiation, were relatively cost-effective options for measuring evaporation at this small New England lake, outperforming some methods that require measurement of a greater number of variables. It is likely that the atmosphere above Mirror Lake was affected by occasional formation of separation eddies on the lee side of nearby high terrain, although those influences do not appear to be significant to measured evaporation from the lake when averaged over monthly periods.