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Great Lakes (great + lake)
Kinds of Great Lakes Terms modified by Great Lakes Selected AbstractsAN ECOLOGICAL REVIEW OF CLADOPHORA GLOMERATA (CHLOROPHYTA) IN THE LAURENTIAN GREAT LAKES,JOURNAL OF PHYCOLOGY, Issue 4 2008Scott N. Higgins Cladophora glomerata (L.) Kütz. is, potentially, the most widely distributed macroalga throughout the world's freshwater ecosystems. C. glomerata has been described throughout North America, Europe, the Atlantic Islands, the Caribbean Islands, Asia, Africa, Australia and New Zealand, and the Pacific Islands. Cladophora blooms were a common feature of the lower North American Great Lakes (Erie, Michigan, Ontario) from the 1950s through the early 1980s and were largely eradicated through the implementation of a multibillion-dollar phosphorus (P) abatement program. The return of widespread blooms in these lakes since the mid-1990s, however, was not associated with increases in P loading. Instead, current evidence indicates that the resurgence in blooms was directly related to ecosystem level changes in substratum availability, water clarity, and P recycling associated with the establishment of dense colonies of invasive dreissenid mussels. These results support the hypothesis that dreissenid mussel invasions may induce dramatic shifts in energy and nutrient flow from pelagic zones to the benthic zone. [source] Tracing recent invasions of the Ponto-Caspian mysid shrimp Hemimysis anomala across Europe and to North America with mitochondrial DNADIVERSITY AND DISTRIBUTIONS, Issue 2 2008Asta Audzijonyte ABSTRACT The mysid crustacean Hemimysis anomala (,bloody-red shrimp') is one of the most recent participants in the invasion of European inland waters by Ponto-Caspian species. Recently the species also became established in England and the Laurentian Great Lakes of North America. Using information from mitochondrial cytochrome oxidase I (COI) gene sequences, we traced the invasion pathways of H. anomala; the inferences were enabled by the observed phylogeographical subdivision among the source area populations in the estuaries of the Ponto-Caspian basin. The data distinguish two routes to northern and western Europe used by distinct lineages. One route has been to and through the Baltic Sea and further to the Rhine delta, probably from a population intentionally introduced to a Lithuanian water reservoir from the lower Dnieper River (NW Black Sea area) in 1960. The other lineage is derived from the Danube delta and has spread across the continent up the Danube River and further through the Main,Danube canal down to the Rhine River delta. Only the Danube lineage was found in England and in North America. The two lineages appear to have met secondarily and are now found intermixed at several sites in NW Europe, including the Rhine and waters linked with the man-made Mittellandkanal that interconnects the Rhine and Baltic drainage systems. [source] Environmental factors affecting the levels of legacy pesticides in the airshed of Delaware and Chesapeake Bays, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2010Anubha Goel Abstract Organochlorine insecticides and their degradation products contribute to toxicity in Chesapeake Bay, USA, sediments and affect the reproductive health of avian species in the region; however, little is known of atmospheric sources or temporal trends in concentrations of these chemicals. Weekly air (n,=,265) and daily rain samples (n,=,494) were collected over 2000 to 2003 from three locations in the Delmarva Peninsula, USA. Pesticides were consistently present in the gas phase with infrequent detection in the particle phase. Hexachlorocyclohexanes (HCHs) and cis - and trans -chlordane were detected most frequently (95,100%), and cis - and trans -nonachlor, oxychlordane, heptachlor, heptachlor epoxide, dieldrin, and 1-chloro-4-[2,2-dichloro-1-(4-chlorophenyl)ethenyl]benzene (4,4,-DDE) were also detected frequently. The highest mean air concentrations were for dieldrin (60,84,pg/m3), ,-HCH (37,83,pg/m3), and 4,4,-DDE (16,80,pg/m3). Multiple regression analyses of air concentrations with temperature and wind conditions using modified Clausius-Clapeyron equations explained only 30 to 60% of the variability in concentration for most chemicals. Comparison of the air concentrations and enthalpy of air,surface exchange values at the three sites indicate sources of chlordanes and ,-HCH sources are primarily from long-range transport. However, examination of chlordane isomer ratios indicates some local and regional contributions, and ,-HCH, 4,4,-DDE, dieldrin, heptachlor, heptachlor epoxide, and oxychlordane also have local or regional sources, possibly from contaminated soils. Median rain sample volumes of 1 to 3 L led to infrequent detections in rain; however, average measured concentrations were 2 to 10 times higher than in the Great Lakes. Dissipation half-lives in air were well below 10 years for all chemicals and below published values for the Great Lakes except dieldrin, which did not decline during the sample period. Environ. Toxicol. Chem. 2010;29:1893,1906. © 2010 SETAC [source] Sampling in the Great Lakes for pharmaceuticals, personal care products, and endocrine-disrupting substances using the passive polar organic chemical integrative samplerENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2010Hongxia Li Abstract The passive polar organic chemical integrative sampler in the pharmaceutical configuration (i.e., pharmaceutical-POCIS) was calibrated for sampling at water temperatures of 5, 15 and 25°C to determine the influence of temperature on chemical-specific sampling rates (RS), thus providing more robust estimates of the time-weighted average concentrations of pharmaceuticals and personal care products (PPCPs) and endocrine-disrupting substances (EDS) in surface water. The effect of water temperature and flow on the RS of these analytes was evaluated in the laboratory with a static system. The loss of the test compounds from water by uptake into POCIS was linear over an 8-d period, and these experimental data yielded RS values in the range of 0.07 to 2.46 L/d across the temperature range for the 30 compounds tested. Water temperature and flow influenced POCIS uptake rates, but these effects were relatively small, which is consistent with the theory for uptake into POCIS samplers. Therefore, under a narrow range of water temperatures and flows, it may not be necessary to adjust the RS for POCIS. Except for acidic drugs and sulfonamide antibiotics, RS values were positively correlated with octanol,water partition coefficients (log KOW) of the test compounds. A linear relationship was also observed between RS and chromatographic retention times on a C18 reversed-phase column. These observations may provide a rapid method for estimating the RS of additional chemicals in the POCIS. The application of the RS to POCIS deployed for one month in Lake Ontario, Canada, during the summers of 2006 and 2008 yielded estimates of PPCP and EDS concentrations that are consistent with conventional concentration measurements of these compounds in Lake Ontario surface water. Environ. Toxicol. Chem. 2010;29:751,762. © 2009 SETAC [source] Polybrominated diphenyl ethers, toxaphenes, and other halogenated organic pollutants in great blue heron eggsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2010Louise Champoux Abstract The great blue heron (Ardea herodias) has been used as a bioindicator of the state of the St. Lawrence River (Québec, Canada) since 1996. At 5-year intervals, selected breeding colonies along the River and its estuary are visited to estimate reproductive success and determine levels of contamination. Brominated flame retardants are found in many ecosystems and are increasing in concentration in the Great Lakes, which is the source of much of the water for the St. Lawrence River. In 2001 and 2002, in addition to polychlorinated biphenyls (PCBs) and chlorinated pesticides, the levels of polybrominated diphenyl ethers (PBDEs), polychlorinated bornanes (toxaphene) congeners and non- ortho -substituted PCBs were measured for the first time in pools of great blue heron eggs. The PBDE levels in great blue heron eggs (70,1,377,ng/g wet wt) were comparable to those measured in herring gull (Larus argentatus) eggs from the Great Lakes. Toxaphene was detected in great blue heron eggs at levels comparable to those of other major chlorinated pesticides. Major toxaphene congeners were octachlorobornane P44 and the nonachlorobornane P50. Environ. Toxicol. Chem. 2010;29:243,249. © 2009 SETAC [source] Using a Geographic Information System to identify areas with potential for off-target pesticide exposureENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2006Thomas G. Pfleeger Abstract In many countries, numerous tests are required as part of the risk assessment process before chemical registration to protect human health and the environment from unintended effects of chemical releases. Most of these tests are not based on ecological or environmental relevance but, rather, on consistent performance in the laboratory. A conceptual approach based on Geographic Information System (GIS) technology has been developed to identify areas that are vulnerable to nontarget chemical exposure. This GIS-based approach uses wind speed, frequency of those winds, pesticide application rates, and spatial location of agricultural crops to identify areas with the highest potential for pesticide exposure. A test scenario based on an incident in Idaho (USA) was used to identify the relative magnitude of risk from off-target movement of herbicides to plants in the conterminous United States. This analysis indicated that the western portion of the Corn Belt, the central California valley, southeastern Washington, the Willamette Valley of Oregon, and agricultural areas bordering the Great Lakes are among those areas in the United States that appear to have the greatest potential for off-target movement of herbicides via drift. Agricultural areas, such as the Mississippi River Valley and the southeastern United States, appears to have less potential, possibly due to lower average wind speeds. Ecological risk assessments developed for pesticide registration would be improved by using response data from species common to high-risk areas instead of extrapolating test data from species unrelated to those areas with the highest potential for exposure. [source] Spatial distribution of polychlorinated naphthalenes in air over the Great Lakes and air-water gas exchange in Lake OntarioENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2003Paul A. Helm Abstract High-volume air sample were collected during research cruises of Lake Superior in August 1996 and May 1977 and of Lake Ontario (North America) in July and September 1998 and June 2000 and analyzed for polychlorinated naphthalenes (PCNs). Levels of tetra- to octachloronaphthalene (,PCN) varied spatially, with mean values (±SD) of 1.78 ± 0.74 and 1.46 ± 1.07 pg m,3 for Lake Superior in 1996 and 1997, respectively, and of 5.53 ± 2.19 and 5.60 ± 2.24 pg m,3 for Lake Ontario in 1998 and 2000, respectively. Evaporative sources were predominant, although combustion marker congeners such as tetrachloronaphthalenes 44 and 29 and pentachloronaphthalene 54 were present in most samples and were enhanced relative to technical PCN mixtures. The ,PCN concentrations were higher in Lake Ontario samples collected in the western half of the lake and when winds were from the west. Greater proportions of the population and industrial areas are located around the western part of Lake Ontario. Water-air fugacity ratios, calculated from air and water samples collected in June 2000, indicate that the trichloronaphthalenes are volatilizing from Lake Ontario, whereas the tetrachloronaphthalenes are close to equilibrium and the net deposition of tetrachloronaphthalenes can occur when the urban air plume influences levels over the lake. [source] A dynamic mass budget for toxaphene in North AmericaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2002Matthew MacLeod Abstract A continental-scale dynamic mass budget for toxaphene in North America is presented, based on available information on physicochemical properties, usage patterns, and reported environmental concentrations and using the Berkeley-Trent North American mass balance contaminant fate model (BETR North America). The model describes contaminant fate in 24 ecological regions of North America, including advective transport between regions in the atmosphere, freshwater, and near-shore coastal water. The dynamic mass budget accounts for environmental partitioning, transport, and degradation of the estimated 534 million kg of toxaphene that were used in North America as an insecticide and piscicide between 1945 and 2000. Satisfactory agreement exists between model results and current and historically reported concentrations of toxaphene in air, water, soil, and sediments throughout North America. An estimated 15 million kg of toxaphene are believed to remain in active circulation in the North American environment in the year 2000, with the majority in soils in the southern United States and Mexico, where historic usage was highest. Approximately 70% of total toxaphene deposition from the atmosphere to the Great Lakes is attributed to sources outside the Great Lakes Basin, and an estimated total of 3.9 million kg of toxaphene have been transported to this region from other parts of the continent. The toxaphene mass budget presented here is believed to be the first reported continental-scalemultimedia mass budget for any contaminant. [source] Distribution of degradation products of alkylphenol ethoxylates near sewage treatment plants in the lower Great Lakes, North AmericaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2000Erin R. Bennett Abstract Degradation of alkylphenol ethoxylate (APEO) surfactants in the environment leads to the formation of relatively hydrophobic compounds such as nonylphenol (NP), octylphenol (OP), nonylphenol monoethoxylate (NP1EO), and nonylphenol diethoxylate (NP2EO) that have been shown to have estrogenic activity. Previous studies have shown that sewage treatment plants (STPs) are point sources for these compounds in the aquatic environment. We collected sediment samples at several sites in the vicinity of STPs in Hamilton Harbour and in the Detroit River to determine the spatial distribution of the degradation products of APEOs. In addition, we deployed semipermeable membrane devices (SPMDs) and caged freshwater mussels (Elliptio complanata) at these locations to determine the distribution of these compounds in the dissolved phase and their potential to bioaccumulate in aquatic organisms. The NP, OP, NP1EO, and NP2EO were found at ,g/g (dry wt.) concentrations in sediments and accumulated to ng/g (wet wt.) concentrations in caged mussels near the STPs. However, in the Detroit River, the concentrations of these compounds declined to near background levels in the sediments, water column (i.e., SPMDs), and biota at stations about 1 km downstream from STPs. At stations in Hamilton Harbour, concentrations of APEO degradation products also declined markedly in sediments and SPMDs located a few hundred meters from the STP. These data indicate that degradation products of APEOs can be accumulated by biota near STPs. However, the environmental distribution of these compounds is localized to areas close to the point of discharge. [source] Temporal variation of energy reserves in mayfly nymphs (Hexagenia spp.) from Lake St Clair and western Lake ErieFRESHWATER BIOLOGY, Issue 10 2003J.F. Cavaletto Summary 1. We analysed changes in energy reserves (lipid and glycogen) and length,weight relationships of burrowing mayflies (Hexagenia spp.) in 1997,99 to compare an established population in Lake St Clair with a recovering population in western Lake Erie of the Laurentian Great Lakes. In addition, we measured changes in water temperature and potential food in both water columns and sediments. 2. Although overall mean values of lipid and glycogen levels of Hexagenia nymphs from Lake St Clair and western Lake Erie were not significantly different, there were differences in seasonal patterns between the two lakes. In Lake St Clair, levels were highest in early spring, declined throughout the year, and reached their lowest levels in fall during all 3 years of study. In contrast, levels in western Lake Erie were lower in spring, increased to a maximum in summer, then declined in fall. Seasonal patterns in length,weight relationships were similar to those for lipid and glycogen. 3. Total lipid as a percentage of dry weight did not increase with developmental stage of nymphs until just prior to metamorphosis and emergence from water. However, the major reserve lipid, triacylglycerols, increased systematically with development stage. In the final stage of development, triacylglycerols declined, probably as a result of energy consumption and its conversion to other biochemical components for metamorphosis and reproduction. 4. Indicators of potential food (algal fluorescence in the water column and chlorophyll a and chlorophyll a/phaeophytin ratio in sediments) suggest that Hexagenia in Lake St Clair have a food source that is benthic based, especially in early spring, whereas in western Lake Erie nymphs have a food source that is water column based and settles to the lake bottom during late spring and summer. [source] Michigan Basin Regional Ground Water Flow Discharge to Three Great LakesGROUND WATER, Issue 4 2002John Robert Hoaglund III Ground water discharge to the Great Lakes around the Lower Peninsula of Michigan is primarily from recharge in riparian basins and proximal upland areas that are especially important to the northern half of the Lake Michigan shoreline. A steady-state finite-difference model was developed to simulate ground water flow in four regional aquifers in Michigan's Lower Peninsula: the Glaciofluvial, Saginaw, Parma-Bayport, and Marshall aquifers interlayered with the Till/"red beds," Saginaw, and Michigan confining units, respectively. The model domain was laterally bound by a continuous specified-head boundary, formed from lakes Michigan, Huron, St. Clair, and Erie, with the St. Clair and Detroit River connecting channels. The model was developed to quantify regional ground water flow in the aquifer systems using independently determined recharge estimates. According to the flow model, local stream stages and discharges account for 95% of the overall model water budget; only 5% enters the lakes directly from the ground water system. Direct ground water discharge to the Great Lakes' shorelines was calculated at 36 m3/sec, accounting for 5% of the overall model water budget. Lowland areas contribute far less ground water discharge to the Great Lakes than upland areas. The model indicates that Saginaw Bay receives only ,1.13 m3/sec ground water; the southern half of the Lake Michigan shoreline receives only ,2.83 m3/sec. In contrast, the northern half of the Lake Michigan shoreline receives more than 17 m3/sec from upland areas. [source] National review of state wildlife action plans for Odonata species of greatest conservation needINSECT CONSERVATION AND DIVERSITY, Issue 2 2010JASON T. BRIED Abstract., 1.,The overarching goal of United States wildlife action plans is to prevent wildlife from becoming endangered or declining to levels where recovery becomes unlikely. Effective plan implementation depends on establishing Species of Greatest Conservation Need (SGCN), defined as wildlife species with small or declining populations or other characteristics that make them vulnerable. 2.,Although nearly two-thirds of distinct Odonata species known from the U.S. (441 species as of 2005) were appointed as SGCN, over half the states neglected to assign dragonfly SGCN, damselfly SGCN, or both. Western and southern states listed proportionately fewer odonate SGCN than states of the Great Lakes, Mid-Atlantic, and New England regions, apparently reflecting geographic patterns of legal authority, available information, and involvement by Odonata specialists. 3.,Greater consultation of Odonata specialists is encouraged in any revision of state wildlife action plans, along with increased: (i) use of existing conservation lists, (ii) inferences from field guides and major faunal synopses, (iii) recognition of patterns of endemism, and (iv) application of empirical species distribution modelling. 4.,Legal and management restrictions aside, insects and other invertebrates are often neglected in mainstream conservation efforts because they are perceived as understudied. It is erroneous to assume ,not enough information' exists for well-studied microfauna such as Odonata and doing so further undermines the conservation of less conspicuous and charismatic taxa. [source] Features of cross-Pacific climate shown in the variability of China and US precipitationINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2005Q. Li Abstract In this study, we have analyzed the climate features of China and the United States with a focus on the differences, similarities, connectivity, and predictability of precipitation and the relationships between precipitation and large-scale patterns of natural variability. China precipitation is characterized by large seasonality, with a maximum in summer and a minimum in winter. The seasonality of precipitation shows an increasing linear tendency in northwest China, with a change of about 20% from 1901 to 1998. A relatively weaker increasing tendency also appears in the Big Bend of Yellow River (BBYR) and the Tibetan Plateau, while southwest China experiences a decreasing tendency. Furthermore, the seasonality in the BBYR shows particularly significant interdecadal variability, while that of southern and eastern China has decreased slightly in the recent decades. Compared to China, the United States as a whole has less precipitation in summer but more precipitation in other seasons. Here, the seasonality of precipitation is only about 24% of that in China. The annual mean precipitation is 64.1 mm per month in the United States, compared to 54.6 mm per month in China. The seasonality of precipitation exhibits a decreasing tendency in the southeast, Pacific Northwest, and Gulf Coast and an increasing tendency in the Great Lakes. The seasonality in the Great Plains exhibits large interdecadal variability. The long-term variations of precipitation are highly seasonally dependent. In summer, a decreasing trend is observed in north China and an increasing trend is found in eastern-central China. However, these trends are almost opposite in spring. In addition, the fall precipitation decreases with time nearly everywhere in China except for the middle and lower reaches of the Yangtze River Valley. Results also indicate that the El Niño/Southern Oscillation (ENSO), the Arctic Oscillation (AO), the North Atlantic Oscillation (NAO), the Pacific Decadal Oscillation (PDO), and the North Pacific (NP) fluctuation affect strongly the variations of China and US precipitation. Although these influences vary with regions and seasons, we in particular emphasize the importance of AO and NAO for China precipitation and NP and PDO for US precipitation. In fall, ENSO and PDO are the two phenomena that influence predominantly precipitation variability in both China and the United States We also identify the common phenomena that influence China and US regional precipitation and provide a better understanding of the physical mechanism for precipitation variability through the associated changes in atmospheric and oceanic conditions. Furthermore, we develop a linear regression model, based on multiple regression method by combining the regionally and seasonally varying impacts, to increase the skill of precipitation prediction. Copyright © 2005 Royal Meteorological Society [source] Zonal circulations over the Indian and Pacific Oceans and the level of lakes Victoria and TanganyikaINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2004Laurent Bergonzini Abstract Level records of two East African Great Lakes, Lake Victoria and Lake Tanganyika, which are considered as hydro-climatic proxies, are analysed. Comparisons between the two lake signals show synchronisms, which can only be accounted for by large-scale mechanisms. Lake-level variations associated with the short rains season (October,January) appear to have a prominent effect on the annual lake levels. The relations between lake-level variations and atmospheric circulation indexes are then investigated. Over the period 1946,2000, four indexes are selected to characterize the October,December zonal circulation over the Pacific and Indian Oceans. Over the Indian Ocean two surface zonal wind indexes (ZWIs) are used. For the Pacific, the southern oscillation index (SOI) and the Niño3 index are held to account for the El Niño,southern oscillation (ENSO). It is shown that significant overall negative correlations of level fluctuations are preferentially obtained with Indian Ocean circulation indexes. Although ZWI is highly correlated with the ENSO indexes, the latter display weaker relations with East African lake levels. It is shown that, for the 1946,2000 period, the October,December zonal circulation cell over the Indian Ocean plays a key role in the equatorial lake-level anomalies, thus demonstrating their influence on the hydro-climatic interannual variability of a large region. However, lake-level variation is a function not only of regional hydro-climatic conditions, but also of the initial (October) absolute lake level. Higher correlations are evident in a multiple correlation approach taking into account the initial lake level status in addition to the ZWI and ENSO indexes. Copyright © 2004 Royal Meteorological Society [source] Mud box,filled with stone: the wreck of the scow schooner Dan HayesINTERNATIONAL JOURNAL OF NAUTICAL ARCHAEOLOGY, Issue 2 2003Bradley A. Rodgers Scow Schooners are an important yet largely unstudied vessel type that operated on the North American Great Lakes. At their zenith in the later 19th century scow schooners worked between the many small harbours and the larger nexus ports such as Chicago, Detroit, and Milwaukee. These vessels are virtually undocumented either historically or archaeologically. A project by East Carolina University's Maritime Studies Program and the State Historical Society of Wisconsin in 2001 documented the wrecked scow schooner Dan Hayes, revealing much information concerning this vessel class and the limestone industry in which it was employed. Although an ordinary scow schooner, its construction techniques are surprising, showing evidence of prefabrication. The bottom of the ship was apparently built inverted and flipped over before sides and bow were added, the first evidence that inverted construction could be accomplished with such large vessels. [source] Importance of the olfactory sense to migratory sea lampreys Petromyzon marinus seeking riverine spawning habitatJOURNAL OF FISH BIOLOGY, Issue 4 2010L. A. Vrieze This study tested the hypothesis that the sea lamprey Petromyzon marinus, a diadromous species of fish, relies on innately discerned odours, including pheromones, to locate riverine spawning habitat. Migratory, sexually immature P. marinus were captured as they entered streams flowing into the Great Lakes, and their olfactory systems were occluded or not by injecting either innocuous dental impression material or a saline control into their nasopores. Animals were then released back into lakes or streams and their recapture rates in stream traps noted. When released into Lake Huron, P. marinus with intact (functional) olfactory systems were very successful in locating rivers (recapture rates ranged up to 65%), while animals with occluded nasopores were virtually unable to do so and had recapture rates five to 20 times lower than intact animals. With few exceptions, intact fish entered the stream closest to their release point within a few days, irrespective of where they had been originally captured; their ability to locate streams is apparently innate and well developed. In contrast, when released within streams, both intact and occluded P. marinus successfully swam upstream to traps for several days although the ability of the former exceeded that of the latter after this period. Migratory P. marinus rely heavily on olfactory cues, of which a larval pheromone is presumably one, to locate river mouths and to a lesser extent to promote upstream movement within rivers. [source] AN ECOLOGICAL REVIEW OF CLADOPHORA GLOMERATA (CHLOROPHYTA) IN THE LAURENTIAN GREAT LAKES,JOURNAL OF PHYCOLOGY, Issue 4 2008Scott N. Higgins Cladophora glomerata (L.) Kütz. is, potentially, the most widely distributed macroalga throughout the world's freshwater ecosystems. C. glomerata has been described throughout North America, Europe, the Atlantic Islands, the Caribbean Islands, Asia, Africa, Australia and New Zealand, and the Pacific Islands. Cladophora blooms were a common feature of the lower North American Great Lakes (Erie, Michigan, Ontario) from the 1950s through the early 1980s and were largely eradicated through the implementation of a multibillion-dollar phosphorus (P) abatement program. The return of widespread blooms in these lakes since the mid-1990s, however, was not associated with increases in P loading. Instead, current evidence indicates that the resurgence in blooms was directly related to ecosystem level changes in substratum availability, water clarity, and P recycling associated with the establishment of dense colonies of invasive dreissenid mussels. These results support the hypothesis that dreissenid mussel invasions may induce dramatic shifts in energy and nutrient flow from pelagic zones to the benthic zone. [source] PHYSIOLOGICAL CHARACTERIZATION OF A SYNECHOCOCCUS SP. (CYANOPHYCEAE) STRAIN PCC 7942 IRON-DEPENDENT BIOREPORTER FOR FRESHWATER ENVIRONMENTS,JOURNAL OF PHYCOLOGY, Issue 1 2003David Porta The complex chemical speciation of Fe in aquatic systems and the uncertainties associated with biological assimilation of Fe species make it difficult to assess the bioavailability of Fe to phytoplankton in relation to total dissolved Fe concentrations in natural waters. We developed a cyanobacterial Fe-responsive bioreporter constructed in Synechococcus sp. strain PCC 7942 by fusing the Fe-responsive isiAB promoter to Vibrio harveyi luxAB reporter genes. A comprehensive physiological characterization of the bioreporter has been made in defined Fraquil medium at free ferric ion concentrations ranging from pFe 21.6 to pFe 19.5. Whereas growth and physiological parameters are largely constrained over this range of Fe bioavailability, the bioreporter elicits a luminescent signal that varies in response to Fe deficiency. A dose-response characterization of bioreporter luminescence made over this range of Fe3+ bioavailability demonstrates a sigmoidal response with a dynamic linear range extending between pFe 21.1 and pFe 20.6. The applicability of using this Fe bioreporter to assess Fe availability in the natural environment has been tested using water samples from Lake Huron (Laurentian Great Lakes). Parallel assessment of dissolved Fe and bioreporter response from these samples reinforces the idea that measures of dissolved Fe should not be considered alone when assessing Fe availability to phytoplankton communities. [source] Metals in the sediments of the Huron-Erie Corridor in North America: Factors regulating metal distribution and mobilizationLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 4 2007Ewa Szalinska Abstract Sediment samples from the Huron-Erie Corridor (Great Lakes, North America) were collected to quantify the relative importance of natural and anthropogenic sources of contamination, and to study the spatial metal distribution patterns of metals as a function of the characteristics of the Corridor sediments. A stratified random sampling design was used to measure the spatial patterns of metal inputs, settling and sorting along the length of the Corridor. Factors regulating metal mobilization were assessed by determining metal affinities with the total organic fraction (TOM), the mineral fraction (represented as Al), and the granulometric characteristic (represented as <0.063 mm fraction). The study revealed that anthropogenic factors primarily regulated metal distributions and mobilization throughout the Huron-Erie Corridor. In the St. Clair and Detroit Rivers, the spatial pattern of metal distributions strongly reflected local industrial sources. In the Walpole Delta and Lake St. Clair, however, inorganic (clays) and organic (TOM) particles dominated the contaminant distribution. Sediment contamination issues throughout the Huron-Erie Corridor were dominated by mercury, released from sources along the St. Clair and Detroit Rivers. The mean enrichment factor EFAl for mercury in these sediments has reached 68.3. Other metal pollutants were confined to the sediments in the lower depositional reach of the Corridor. [source] Ongoing ecological divergence in an emerging genomic modelMOLECULAR ECOLOGY, Issue 14 2009MATTHEW E. ARNEGARD Much of Earth's biodiversity has arisen through adaptive radiation. Important avenues of phenotypic divergence during this process include the evolution of body size and life history (Schluter 2000). Extensive adaptive radiations of cichlid fishes have occurred in the Great Lakes of Africa, giving rise to behaviours that are remarkably sophisticated and diverse across species. In Tanganyikan shell-brooding cichlids of the tribe Lamprologini, tremendous intraspecific variation in body size accompanies complex breeding systems and use of empty snail shells to hide from predators and rear offspring. A study by Takahashi et al. (2009) in this issue of Molecular Ecology reveals the first case of genetic divergence between dwarf and normal-sized morphs of the same nominal lamprologine species, Telmatochromis temporalis. Patterns of population structure suggest that the dwarf, shell-dwelling morph of T. temporalis might have arisen from the normal, rock-dwelling morph independently in more than one region of the lake, and that pairs of morphs at different sites may represent different stages early in the process of ecological speciation. The findings of Takahashi et al. are important first steps towards understanding the evolution of these intriguing morphs, yet many questions remain unanswered about the mating system, gene flow, plasticity and selection. Despite these limitations, descriptive work like theirs takes on much significance in African cichlids due to forthcoming resources for comparative genomics. [source] Invasion genetics of the Eurasian round goby in North America: tracing sources and spread patternsMOLECULAR ECOLOGY, Issue 1 2009JOSHUA E. BROWN Abstract The Eurasian round goby Neogobius melanostomus (Apollonia melanostoma) invaded the North American Great Lakes in 1990 through ballast water, spread rapidly, and now is widely distributed and moving through adjacent tributaries. We analyse its genetic diversity and divergence patterns among 25 North American (N = 744) and 22 Eurasian (N = 414) locations using mitochondrial DNA cytochrome b gene sequences and seven nuclear microsatellite loci in order to: (i) identify the invasion's founding source(s), (ii) test for founder effects, (iii) evaluate whether the invasive range is genetically heterogeneous, and (iv) determine whether fringe and central areas differ in genetic diversity. Tests include FST analogues, neighbour-joining trees, haplotype networks, Bayesian assignment, Monmonier barrier analysis, and three-dimensional factorial correspondence analysis. We recovered 13 cytochrome b haplotypes and 232 microsatellite alleles in North America and compared these to variation we previously described across Eurasia. Results show: (i) the southern Dnieper River population was the primary Eurasian donor source for the round goby's invasion of North America, likely supplemented by some alleles from the Dniester and Southern Bug rivers, (ii) the overall invasion has high genetic diversity and experienced no founder effect, (iii) there is significant genetic structuring across North America, and (iv) some expansion areas show reduced numbers of alleles, whereas others appear to reflect secondary colonization. Sampling sites in Lake Huron's Saginaw Bay and Lake Ontario significantly differ from all others, having unique alleles that apparently originated from separate introductions. Substantial genetic variation, multiple founding sources, large number of propagules, and population structure thus likely aided the goby's ecological success. [source] Contrasting patterns in genetic diversity following multiple invasions of fresh and brackish watersMOLECULAR ECOLOGY, Issue 12 2006DAVID W. KELLY Abstract Biological invasions may combine the genetic effects of population bottlenecks and selection and thus provide valuable insight into the role of such processes during novel environmental colonizations. However, these processes are also influenced by multiple invasions, the number of individuals introduced and the degree of similarity between source and receiving habitats. The amphipod Gammarus tigrinus provides a useful model to assess these factors, as its invasion history has involved major environmental transitions. This species is native to the northwest Atlantic Ocean, although it invaded both brackish and freshwater habitats in the British Isles after introduction more than 65 years ago. It has also spread to similar habitats in Western Europe and, most recently, to Eastern Europe, the Baltic Sea, and the Laurentian Great Lakes. To examine sources of invasion and patterns of genetic change, we sampled populations from 13 native estuaries and 19 invaded sites and sequenced 542 bp of the mitochondrial COI gene. Strong native phylogeographical structure allowed us to unambiguously identify three allopatrically evolved clades (2.3,3.1% divergent) in invading populations, indicative of multiple introductions. The most divergent clades occurred in the British Isles and mainland Europe and were sourced from the St Lawrence and Chesapeake/Delaware Bay estuaries. A third clade was found in the Great Lakes and sourced to the Hudson River estuary. Despite extensive sampling, G. tigrinus did not occur in freshwater at putative source sites. Some European populations showed reduced genetic diversity consistent with bottlenecks, although selection effects cannot be excluded. The habitat distribution of clades in Europe was congruent with the known invasion history of secondary spread from the British Isles. Differences in salinity tolerance among lineages were suggested by patterns of habitat colonization by different native COI clades. Populations consisting of admixtures of the two invading clades were found principally at recently invaded fresh and brackish water sites in Eastern Europe, and were characterized by higher genetic diversity than putative source populations. Further studies are required to determine if these represent novel genotypes. Our results confirm that biological invasions need not result in diminished genetic diversity, particularly if multiple source populations, each with distinctive genetic composition, contribute to the founding populations. [source] Molecular ecology of zebra mussel invasionsMOLECULAR ECOLOGY, Issue 4 2006GEMMA E. MAY Abstract The invasion of the zebra mussel, Dreissena polymorpha, into North American waters has resulted in profound ecological disturbances and large monetary losses. This study examined the invasion history and patterns of genetic diversity among endemic and invading populations of zebra mussels using DNA sequences from the mitochondrial cytochrome oxidase I (COI) gene. Patterns of haplotype frequency indicate that all invasive populations of zebra mussels from North America and Europe originated from the Ponto-Caspian Sea region. The distribution of haplotypes was consistent with invasive populations arising from the Black Sea drainage, but could not exclude the possibility of an origin from the Caspian Sea drainage. Similar haplotype frequencies among North American populations of D. polymorpha suggest colonization by a single founding population. There was no evidence of invasive populations arising from tectonic lakes in Turkey, while lakes in Greece and Macedonia contained only Dreissena stankovici. Populations in Turkey might be members of a sibling species complex of D. polymorpha. Ponto-Caspian derived populations of D. polymorpha (, = 0.0011) and Dreissena bugensis (one haplotype) exhibited low levels of genetic diversity at the COI gene, perhaps as a result of repeated population bottlenecks. In contrast, geographically isolated tectonic lake populations exhibited relatively high levels of genetic diversity (, = 0.0032 to 0.0134). It is possible that the fluctuating environment of the Ponto-Caspian basin facilitated the colonizing habit of invasive populations of D. polymorpha and D. bugensis. Our findings were concordant with the general trend of destructive freshwater invaders in the Great Lakes arising from the Ponto-Caspian Sea basin. [source] The Archaeology of Native-Lived Colonialism: Challenging History in the Great Lakes by Neal FerrisAMERICAN ANTHROPOLOGIST, Issue 1 2010Kurt A. Jordan No abstract is available for this article. [source] Une histoire de résidus : à propos des facteurs généraux et locaux de croissance régionale au Canada, de 1971 à 2001THE CANADIAN GEOGRAPHER/LE GEOGRAPHE CANADIEN, Issue 4 2009PHILIPPE APPARICIO local economic development; regional growth models; centre-periphery En partant d'un modèle géostatistique d'explication des variations locales de croissance d'emploi pour le Canada (1971,2001), les résidus , par rapport aux prédictions , sont analysés dans le temps et dans l'espace, permettant ainsi de faire la distinction entre, d'une part, des facteurs à portée générale et, d'autre part, des facteurs proprement locaux, conjoncturels ou aléatoires. Le pouvoir d'explication du modèle, qui intègre des variables telles que la taille, la distance et les structures industrielles s'accroît dans le temps, si bien que la dynamique spatiale de l'économie canadienne s'aligne de plus en plus sur des grandes variables géo-structurelles. Toutefois, un regard sur les résidus révèle des processus plus localisés. La volatilité des trajectoires est surtout manifeste en Alberta et en Colombie-Britannique, qui abritent les économies locales les plus erratiques. Des processus émergents se devinent pour la dernière période, dont la sous-performance du Nord ontarien et des localités non-métropolitaines sur l'axe Québec-Windsor, riveraines du Saint-Laurent et des Grands-Lacs. En contrepartie, la surperformance de villes moyennes du Sud-est québécois laisse deviner des processus proprement locaux, associés au dynamisme de l'entreprenariat local. Starting from an econometric model of local employment growth, applied to Canada (1971,2001), residuals,relative to model predictions,are analyzed over time and over space, in turn allowing us to draw a distinction between general explanatory variables and factors of a more local, cyclical or accidental nature. The model's explanatory power grows over time, founded on variables such as urban size, market access and industrial structure, allowing us to conclude that local employment growth in Canada follows an increasingly geographically predictable pattern. However, an examination of the residuals reveals more localized processes. Growth volatility is most manifest in Alberta and British Columbia, home to the most erratic local economies. Emerging patterns are visible in the last period, most notably the underperformance of Northern Ontario and of non-metropolitan communities between Windsor and Québec City, lying along the Great Lakes and the Saint Lawrence. The over-performance,compared to model predictions , of small and mid-sized towns in south-eastern Québec can, on the other hand, be interpreted as a sign of truly local social processes, generally associated with a particularly dynamic local entrepreneurial class. [source] Legislation and the capacity for rapid-response management of nonindigenous species of fish in contiguous waters of Canada and the USAAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 3 2009Vernon G. Thomas Abstract 1.The provision of Canadian and US hard, enforceable, law to authorize rapid response management of nonindigenous aquatic species originating from aquaculture, live fish sales, bait fish, and the pet trade was analysed at the provincial/state levels of government for the Atlantic, Laurentian Great Lakes, and Pacific regions of North America. 2.No federal legal capacity for rapid response management exists in either country. US state legislation is generally better developed than Canadian provincial laws to manage the exotic fish trade. However, much discrepancy exists among provincial and state law regarding provisions to restrict or prohibit potentially harmful species. Aquaculture and baitfish use is generally better regulated than live fish markets and the pet fish trade in both countries. Only the state of Maine has laws authorizing rapid-response management to control escaped exotic fish. 3.Most species of nonindigenous fish arise from the aquarium, pet, and baitfish trades, and development of improved legislation containing provisions for rapid response management of escapees is warranted in all states and provinces. 4.It is recommended that Canada amends the Fisheries Act to create the appropriate enabling legislation to monitor, assess risk, and deploy rapid response management of nonindigenous aquatic species, including fish that enter federal fresh and sea waters. Two recently-introduced US Bills, S. 725 and H.R. 1350, with their explicit measures for early detection and fast action response, could, if passed into law, create provisions to control introduced nuisance species throughout North American waters. They would also create precedents for states and provinces that have most jurisdiction over aquaculture and trade in exotic fish to amend and align their laws in a complementary manner. Copyright © 2008 John Wiley & Sons, Ltd. [source] A developing paradigm for the development of bird beaksBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2006PETER R. GRANT Some adaptive radiations are notable for extreme interspecific diversification in one or a few adult traits. How and why have trait differences evolved? Natural and sexual selection often provide answers to the question of why. An answer to the question of how is to be found in the genetic control of the phenotypic traits, especially in the early stages of development, when interspecific differences first become expressed. Recent studies of the molecular genetic control of beak development in Darwin's finches have shown that a signalling molecule (BMP4) plays a key role in the development of large and deep beaks. Expression of this molecule occurs earlier (heterochrony) and at higher levels in species with deep beaks compared with species with more pointed beaks. The implication of this finding is that variation in the regulation of one or a few genes that are expressed early could be the source of evolutionarily significant variation that is subject to natural selection in speciation and adaptive radiation. This view is reinforced by parallel findings with the same signalling molecule in the development of jaw morphology in cichlid fish of the Great Lakes of Africa. Further research into regulatory mechanisms is to be expected, as well as extension to other examples of radiation such as honeycreepers in Hawaii and Anolis lizards in the Caribbean. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 17,22. [source] A Place Where I Can Let My Hair Down: from social club to cultural center in an urban Indian communityCITY & SOCIETY, Issue 1 2001Deborah Davis Jackson The "Riverton" Indian Center was established in the 1950s as large numbers of Native Americans migrated to the city from reservations around the Great Lakes and beyond, and underwent significant changes throughout the second half of the twentieth century. These changes, and the conflicts that resulted from them, were shaped by far larger political,economic and cultural forces: on the one hand, River ton's economy, along with the economies of many midsized cities in the Great Lakes region,was undergoing rapid deindustrialization with devastating consequences to local residents, including American Indians; on the other hand, social and cultural changes in the U.S., starting in the 1960s, made Native Americans,or at least a romanticized image of Native Americans,increasingly popular with non-Natives. These forces converged to create the three distinct phases in the Riverton Indian Center's history, each associated with a particular age cohort,a trajectory that might well be typical of deindustrializing cities in the Great Lakes region. [American Indians; community and identity; deindistrialivng cities; Upper Great Lakes region] [source] Institutional arrangements for managing the great lakes of the world: Results of a workshop on implementing the watershed approachLAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 3 2001Lisa Borre Abstract The conceptual framework for lake management has evolved at an accelerating rate in recent years to include the basic principles of a watershed approach: (i) citizen and stakeholder involvement is important throughout the planning and management process; (ii) the geographic focus for management activities includes the lake and its entire watershed; and (iii) mechanisms need to be in place to promote cooperation among different government jurisdictions and organizations in the watershed. Creating effective institutional arrangements for implementing this watershed approach in lake regions is perhaps the most challenging and important issue facing the world's lakes. LakeNet organized a workshop at the 8th International Conference on the Conservation and Management of Lakes in May 1999. This article is a synthesis of the results of the workshop and the eight case reports prepared by the workshop participants published in this special issue. Seven major threats to lakes were identified: (i) accelerated eutrophication; (ii) invasive species; (iii) toxic contamination; (iv) overfishing; (v) water diversion, (vi) acidification; and (vii) climate change. Institutions and institutional arrangements for addressing these issues and for implementing a watershed approach are just beginning to emerge on lakes around the world. All of the institutions described in the case reports were established or formalized during the 1980s and 1990s. The legal mechanisms creating these institutions range from cooperative agreements among jurisdictions for purposes of policy and planning to national laws and international treaties with full regulatory powers. The knowledge base, political will and financial resources for these activities were very small in comparison with the complexity of the task at hand. [source] | ||||||||||||||||