Responses of Hyalella azteca and Ceridaphnia dubia to reservoir sediments following Chelated Copper Herbicide Applications

In response to nuisance growths of algae and vascular plants, such as dioecious hydrilla ( Hydrilla verticillata L.f. Royle), copper formulations have been applied in lakes and reservoirs for a number of years. Concerns have arisen regarding the long-term consequences of copper applications and those concerns have appropriately focused on sediment residues. In this study, we evaluated the toxicity of sediments from treated (for a decade) and untreated areas in Lake Murray, South Carolina and estimated the capacity of those sediments to bind additional copper. Two sentinel aquatic invertebrates, Hyalella azteca Saussure and Ceriodaphnia dubia Richard, were used to measure residual toxicity of treated and untreated sediments from the field and after laboratory amendments. (PDF has 5 pages.)

Relative tolerance of mat-forming algae to copper

This study documents the relative tolerance of the common, weedy mat-forming green algae Hydrodictyon , Oedogonium , Pithophora , Rhizoclonium , and Spirogyra to copper. In addition, the copper tolerance of the cyanobacterial (blue-green algal) mat-forming Oscillatoria was assessed.

Letter from the Editor: special issue of papers on “The Use of Native Insect Herbivores for the Management of Eurasian Watermilfoil," presented at a special session of the Annual Meeting, Aquatic Plant Management Society, July 1998, Memphis, TN

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Factors to consider when using native biological control organisms to manage exotic plants

Biological control of exotic plant populations with native organisms appears to be increasing, even though its success to date has been limited. Although many researchers and managers feel that native organisms are easier to use and present less risk to the environment this may not be true. Developing a successful management program with a native insect is dependent on a number of critical factors that need to be considered. Information is needed on the feeding preference of the agent, agent effectiveness, environmental regulation of the agent, unique requirements of the agent, population maintenance of the agent, and time to desired impact. By understanding these factors, researchers and managers can develop a detailed protocol for using the native biological control agent for a specific target plant. . We found E. lecontei in 14 waterbodies, most of which were in eastern Washington. Only one lake with weevils was located in western Washington. Weevils were associated with both Eurasian ( Myriophyllum spicatum L.) and northern watermilfoil ( M. sibiricum K.). Waterbodies with E. lecontei had significantly higher ( P < 0.05) pH (8.7 ± 0.2) (mean ± 2SE), specific conductance (0.3 ± 0.08 mS cm -1 ) and total alkalinity (132.4 ± 30.8 mg CaCO 3 L -1 ). We also found that weevil presence was related to surface water temperature and waterbody location ( = 24.3, P ≤ 0.001) and of all the models tested, this model provided the best fit (Hosmer- Lemeshow goodness-of-fit = 4.0, P = 0.9). Our results suggest that in Washington State E. lecontei occurs primarily in eastern Washington in waterbodies with pH ≥ 8.2 and specific conductance ≥ 0.2 mS cm -1 . Furthermore, weevil distribution appears to be correlated with waterbody location (eastern versus western Washington) and surface water temperature.

Panel Discussion - Management of Eurasian watermilfoil in the United States using native insects: State regulatory and management issues

While researchers have evaluated the potential of native insect herbivores to manage nonindigenous aquatic plant species such as Eurasian watermilfoil ( Myriophyllum spicatum L.), the practical matters of regulatory compliance and implementation have been neglected. A panel of aquatic nuisance species program managers from three state natural resource management agencies (Minnesota, Vermont and Washington) discussed their regulatory and policy concerns. In addition, one ecological consultant attempting to market one of the native insects to manage Eurasian watermilfoil added his perspective on the special challenges of distributing a native biological control agent for management of Eurasian watermilfoil.

A manual of previously recorded non-indigenous invasive and native transplanted animal species of the Laurentian Great Lakes and coastal United States

This manual presents geographic information by state of occurrence, and descriptions of the socio-economic impact created by the invasion of non-indigenous and native transplanted animal species in the Laurentian Great Lakes and the coastal waters of the United States. It is not a comprehensive literature review, but rather is intended as a primer for those unfamiliar with the socio-economic impacts of invasive aquatic and marine animals. Readers should also note that the information contained in this manual is current as of its publication date. New information and new species are routinely being added to the wider literature base. Most of the information was gathered from a number of web sites maintained by government agencies, commissions, academic institutions and museums. Additional information was taken from the primary and secondary literature. This manual focuses on socio-economic consequences of invasive species. Thus, ecological impacts, when noted in the literature, are not discussed unless a connection to socio-economic factors can be made. For a majority of the species listed, either the impact of their invasion is not understood, or it is not published in sources surveyed. In the species summaries, sources of information are cited except for information from the U.S. Geological Survey’s (USGS) Nonindigenous Aquatic Species Database http://nas.er.usgs.gov. This website formed the base information used in creating tables on geographic distribution, and in many of the species summaries provided. Thus, whenever information is given without specific author/source and date citation, it has come from this comprehensive source. (PDF contains 90 pages)

The distribution of native and introduced species of crayfish in Austria

This account concentrates on the six species of crayfish found in Austria, and the current state of knowledge on their distribution and laws affecting conservation. In general the occurrence and distribution of crayfish in Austria is poorly known, although information obtained by researchers and the general public, after careful checking, is increasing. Three native crayfish species occur in Austria: Austropotamobius torrentium which is relatively widespread, A. pallipes with a restricted distribution, and Astacus astacus which is widespread. Three species of non-native (alien) crayfish have been recorded from a total of 158 localities in Austria. They are Astacus leptodactylus from eastern Europe, and two Nearctic species: Pacifastacus leniusculus and Orconectes limosus. The introduction of alien species causes considerable problems as they act as vectors of crayfish plague and are able to outcompete native species by higher reproductive capacities.

An assessment of post-plague reintroduced native white-clawed crayfish, a Ustropotamobius pallipes, in the Sherston Avon and Tetbury Avon, Wiltshire

This article reports on the success of reintroducing native crayfish (Austropotamobius pallipes) in the Sherston and Tetbury Avon, following extinction of the population from crayfish plague. The authors describe and review the survey methods that were used and identify a survey technique that was found to be the most rapid and robust for monitoring crayfish populations. Such a survey technique could be adopted as a standard method.

The current distribution of signal and native crayfish in the Broadmead Brook, Wiltshire

Signal crayfish (Pacifastacus leniusculus) have existed in the upper reaches of Broadmead Brook in Wiltshire since 200 individuals were introduced at West Kington in 1981. The population has expanded upstream and downstream since this introduction, however, giving rise to concerns that it may potentially threaten the native crayfish population further downstream. Signal crayfish can act as a vector of crayfish plague - a disease caused by the fungus Aphanomyces astaci Schikora which results in almost complete mortality to the native, white-clawed crayfish Austropotamobius pallipes. The native crayfish in Broadmead Brook have not yet succumbed to crayfish plague and are currently free of the disease. However, as signal crayfish appear to out-compete the native species, the native population could still be under threat. In this article, we highlight the findings of previous crayfish surveys on Broadmead Brook and describe work undertaken in summer 2001 to map the current distribution of native and signal crayfish. Finally, options for controlling the spread of signal crayfish are discussed.

Metallothionein as an indicator of water quality: assessment of the bioavailability of cadmium, copper, mercury and zinc in aquatic animals at the cellular level

The study of metallothioneins (MTs) has greatly improved our understanding of body burdens, metal storage and detoxification in aquatic organisms subjected to contamination by the toxic heavy metals, Cd, Cu, Hg and Zn. These studies have shown that in certain organisms MT status can be used to assess impact of these metals at the cellular level and, whilst validation is currently limited to a few examples, this stress response may be linked to higher levels of organisation, thus indicating its potential for environmental quality assessment. Molluscs, such as Mytilus spp., and several commonly occurring teleost species, are the most promising of the indicator species tested. Natural variability of MT levels caused by the organism's size, condition, age, position in the sexual cycle, temperature and various stressors, can lead to difficulties in interpretation of field data as a definitive response-indicator of metal contamination unless a critical appraisal of these variables is available. From laboratory and field studies these data are almost complete for teleost fish. Whilst for molluscs much of this information is lacking, when suitable controls are utilised and MT measurements are combined with observations of metal partitioning, current studies indicate that they are nevertheless a powerful tool in the interpretation of impact, and may prove useful in water quality assessment.

Physiological Determinants of Invasive Success Linking Distribution Patterns to Metabolic Physiology in Native and Invasive Blue Mussels (genus Mytilus)

In the early 20th century, a blue mussel species from the Mediterranean invaded the California coast and subsequently out-competed the native species south of Monterey Bay. Like other invasive species, Mytilus galloprovincialis has physiological traits that make it successful in habitats formerly occupied by the native M. trossulus, namely its adaptation to warm sea surface temperatures. This study looks at the current genotype distributions and enzymatic activities of field-acclimatized mussels within the hybrid zone where the species co-occur as well as mussels that have been acclimated for four weeks to different temperature and salinity conditions. In the field-acclimatized and laboratory-acclimated mussels, the native species exhibited significantly higher enzyme rates, which may reflect an evolutionary adaptation to compensate to low habitat temperatures. Indeed, the results of the laboratory acclimation indicate that these differences are genetically based. Whether an acclimation capacity exists may require even longer-term acclimation to different temperatures. Current findings suggest that the further spread of the invasive species is likely to be governed in large measure by the potentially counteracting effects of rising temperatures, which would favor the northerly spread of M. galloprovincialis, and increased winter precipitation, which would favor the persistence of M. trossulus. However, the success of M. galloprovincialis during acclimation to ‘dilute’ salinity (25 ppt) suggests that the invasive species can tolerate a greater salinity range than previously thought. Thus, further investigation is needed to build a comprehensive predictive model of the movement of M. galloprovincialis and the hybrid zone along the California coast.

The effect of organotin and copper sulfate on the late development and presettlement behavior of the hard clam Mercenaria mercenaria

The effect of organotin compounds and copper, commonly used as antifouling agent, were studied on Mercenaria mercernaria larvae. They were reared under usual hatchery conditions until they reached 190 um in diameter. The larvae were subjected to four compounds, tributylin chloride (TBT), monobutyltin chloride (MBT), trimethyltin chloride (TMT), cupric sulfate (CuSo4) plus control. Mortality was measured at 24, 48 h, and 96h. Behavioral and/or metamorphic changes were recorded in triplicate at 24-48 and 96 h. The appearance in swimming larvae of a functional foot was considered a sign of competence to set and was recorded as a "pediveliger". Swimming larvae were considered as larvae that have not yet reached their total development and they were recorded as "swimming". Larvae that did not show foot or swimming activity and were static but alive on the bottom were recorded as "bottom". TBT was found to completely inhibit swimming activity at sublethal concentrations throughout the period of observation. Copper and MBT inhibited swimming from 48 h, TMT did not inhibit swimming activity at any of the times recorded. The four compounds ranked in order of decreasing toxicity were TBT>TMT>CU>MBT.