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Ecological Effects (ecological + effects)
Selected AbstractsMacrophytes in Urban Stream Rehabilitation: Establishment, Ecological Effects, and Public PerceptionRESTORATION ECOLOGY, Issue 3 2006Scott T. Larned Abstract Efforts to rehabilitate degraded urban streams generally focus on improving physical habitat and rarely include reestablishing biota such as macrophytes. Our objectives in this study were to propagate and transplant native macrophytes into a South Island, New Zealand, urban stream undergoing rehabilitation, assess macrophyte survival and growth, and determine whether native macrophytes suppress non-native macrophytes and/or enhance stream invertebrate communities. Effects of native macrophytes on invertebrates and non-native macrophytes were assessed after transplanting patches of native macrophytes into a 230-m-long stream section. A 100-m-long section upstream was left unplanted for subsequent comparisons. Following the study, a survey was conducted to gauge public opinion about the rehabilitation project and determine whether macrophytes were prominent in perceptions of stream health. In the first growing season, native macrophyte cover in the planted stream section increased from 1.5 to 20%, and then decreased during winter. Regrowth from rhizomes led to rapid aboveground growth during the second year, when cover reached 51%. Non-native macrophytes colonized the stream the first year, but native macrophytes appeared to limit the spread of non-natives, which were absent in the planted section by the second spring. Native macrophyte establishment did not enhance invertebrate communities as predicted; few invertebrate metrics differed significantly between the planted and unplanted sections. Pollution- and sediment-tolerant invertebrate taxa were abundant in both sections, suggesting that invertebrate colonization was limited by water quality or sedimentation, not macrophyte composition. Survey respondents considered the stream to be visually and ecologically improved after rehabilitation, and macrophyte establishment was generally considered positive or neutral. [source] Evaluating Indirect Ecological Effects of Biological ControlAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 1 2002Article first published online: 26 FEB 200 No abstract is available for this article. [source] Effects of stocked trout on native fish communities in boreal foothills lakesECOLOGY OF FRESHWATER FISH, Issue 2 2010Leslie E. Nasmith Nasmith LE, Tonn WM, Paszkowski CA, Scrimgeour GJ. Effects of stocked trout on native fish communities in boreal foothills lakes. Ecology of Freshwater Fish 2010: 19: 279,289. © 2010 John Wiley & Sons A/S Abstract,,, Ecological effects of stocking nonnative trout into lakes are receiving increased attention, especially in alpine environments. We assessed effects of stocked trout on native forage fishes in the boreal foothills of Alberta (Canada) by comparing fish density, population size structure and spatial and temporal activities in stocked and unstocked lakes over 3 years (2005,2007). The numerically dominant dace (primarily Phoxinus spp.) were larger in stocked lakes, consistent with size-limited predation. Dace were also more crepuscular and concentrated on the lake-bottom in stocked lakes, compared to more daytime activity in the water column in unstocked lakes. There were, however, no demonstrable effects of trout on the abundance of forage fish. The lack of major population-level impacts of stocked trout suggests that current stocking practices, characteristics of boreal foothill lakes (e.g. thermal structure, abundant invertebrates, dense macrophytes) and/or behavioural adjustments of forage fish contribute to healthy native fish populations in our stocked lakes. [source] Ecological effects of regime shifts in the Bering Sea and eastern North Pacific OceanFISH AND FISHERIES, Issue 2 2002Ashleen J Benson Abstract Large-scale shifts occurred in climatic and oceanic conditions in 1925, 1947, 1977, 1989 and possibly 1998. These shifts affected the mix and abundance of suites of coexisting species during each period of relative environmental stability,from primary producers to apex predators. However, the 1989 regime shift was not a simple reversal of the 1977 shift. The regime shifts occurred abruptly and were neither random variations nor simple reversals to the previous conditions. Timing of these anomalous environmental events in the North Pacific Ocean appears to be linked to physical and biological responses in other oceanic regions of the world. Changes in the atmospheric pressure can alter wind patterns that affect oceanic circulation and physical properties such as salinity and depth of the thermocline. This, in turn, affects primary and secondary production. Data from the North Pacific indicate that regime shifts can have opposite effects on species living in different domains, or can affect similar species living within a single domain in opposite ways. Climatic forcing appears to indirectly affect fish and marine mammal populations through changes in the distribution and abundance of their predators and prey. Effects of regime shifts on marine ecosystems are also manifested faster at lower trophic levels. Natural variability in the productivity of fish stocks in association with regime shifts indicates that new approaches to managing fisheries should incorporate climatic as well as fisheries effects. [source] Ecological effects of perturbation by drought in flowing watersFRESHWATER BIOLOGY, Issue 7 2003P. S. Lake SUMMARY 1Knowledge of the ecology of droughts in flowing waters is scattered and fragmentary, with much of the available information being gathered opportunistically. Studies on intermittent and arid-zone streams have provided most of the information. 2Drought in streams may be viewed as a disturbance in which water inflow, river flow and water availability fall to extremely low levels for extended periods of time. As an ecological perturbation, there is the disturbance of drought and the responses of the biota to the drought. 3Droughts can either be periodic, seasonal or supra-seasonal events. The types of disturbance for seasonal droughts are presses and for supra-seasonal droughts, ramps. 4In droughts, hydrological connectivity is disrupted. Such disruption range from flow reduction to complete loss of surface water and connectivity. The longitudinal patterns along streams as to where flow ceases and drying up occurs differs between streams. Three patterns are outlined: ,downstream drying', ,headwater drying' and ,mid-reach drying'. 5There are both direct and indirect effects of drought on stream ecosystems. Marked direct effects include loss of water, loss of habitat for aquatic organisms and loss of stream connectivity. Indirect effects include the deterioration of water quality, alteration of food resources, and changes in the strength and structure of interspecific interactions. 6Droughts have marked effects on the densities and size- or age-structure of populations, on community composition and diversity, and on ecosystem processes. 7Organisms can resist the effects of drought by the use of refugia. Survival in refugia may strongly influence the capacity of the biota to recover from droughts once they break. 8Recovery by biota varies markedly between seasonal and supra-seasonal droughts. Faunal recovery from seasonal droughts follows predictable sequences, whilst recovery from supra-seasonal droughts varies from one case to another and may be marked by dense populations of transient species and the depletion of biota that normally occur in the streams. 9The restoration of streams must include the provision of drought refugia and the inclusion of drought in the long-term flow regime. [source] Ecological effects of changes in fire regimes in Pinus ponderosa ecosystems in the Colorado Front RangeJOURNAL OF VEGETATION SCIENCE, Issue 6 2006Rosemary L. Sherriff Abstract Question: What is the relative importance of low- and high-severity fires in shaping forest structure across the range of Pinus ponderosa in northern Colorado? Location: Colorado Front Range, USA. Methods: To assess severities of historic fires, 24 sites were sampled across an elevation range of 1800 to 2800 m for fire scars, tree establishment dates, tree mortality, and changes in tree-ring growth. Results: Below 1950 m, the high number of fire scars, scarcity of large post-fire cohorts, and lack of synchronous tree mortality or growth releases, indicate that historic fires were of low severity. In contrast, above 2200 m, fire severity was greater but frequency of widespread fires was substantially less. At 18 sites above 1950 m, 34 to 80% of the live trees date from establishment associated with the last moderate- to high-severity fire. In these 18 sites, only 2 to 52% of the living trees pre-date these fires suggesting that fire severities prior to any effects of fire suppression were sufficient to kill many trees. Conclusions: These findings for the P. ponderosa zone above ca. 2200 m (i.e. most of the zone) contradict the widespread perception that fire exclusion, at least at the stand scale of tens to hundreds of hectares, has resulted in unnaturally high stand densities or in an atypical abundance of shade-tolerant species. At relatively mesic sites (e.g. higher elevation, north-facing), the historic fire regime consisted of a variable-severity regime, but forest structure was shaped primarily by severe fires rather than by surface fires. [source] A method to assess longitudinal riverine connectivity in tropical streams dominated by migratory biota,AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2009Kelly E. Crook Abstract 1.One way in which dams affect ecosystem function is by altering the distribution and abundance of aquatic species. 2.Previous studies indicate that migratory shrimps have significant effects on ecosystem processes in Puerto Rican streams, but are vulnerable to impediments to upstream or downstream passage, such as dams and associated water intakes where stream water is withdrawn for human water supplies. Ecological effects of dams and water withdrawals from streams depend on spatial context and temporal variability of flow in relation to the amount of water withdrawn. 3.This paper presents a conceptual model for estimating the probability that an individual shrimp is able to migrate from a stream's headwaters to the estuary as a larva, and then return to the headwaters as a juvenile, given a set of dams and water withdrawals in the stream network. The model is applied to flow and withdrawal data for a set of dams and water withdrawals in the Caribbean National Forest (CNF) in Puerto Rico. 4.The index of longitudinal riverine connectivity (ILRC), is used to classify 17 water intakes in streams draining the CNF as having low, moderate, or high connectivity in terms of shrimp migration in both directions. An in-depth comparison of two streams showed that the stream characterized by higher water withdrawal had low connectivity, even during wet periods. Severity of effects is illustrated by a drought year, where the most downstream intake caused 100% larval shrimp mortality 78% of the year. 5.The ranking system provided by the index can be used as a tool for conservation ecologists and water resource managers to evaluate the relative vulnerability of migratory biota in streams, across different scales (reach-network), to seasonally low flows and extended drought. This information can be used to help evaluate the environmental tradeoffs of future water withdrawals. Copyright © 2009 John Wiley & Sons, Ltd. [source] Ecological effects of major injuries in diamondback terrapins: implications for conservation and managementAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2009K. K. Cecala Abstract 1.Many turtle species frequently suffer major injuries due to attempted predation or anthropogenic factors. Diamondback terrapins (Malaclemys terrapin) are one species known to be affected by anthropogenic activity, but little is known about the causes of injuries. In declining diamondback terrapin populations, learning more about causes and results of injuries can be helpful in developing sound management plans. 2.Patterns of limb loss and major shell injuries were examined in a population of terrapins studied for 24 years at Kiawah Island, South Carolina to infer the causes and effects of injuries and possible predators on terrapins. 3.The rate of shell injuries increased temporally, possibly as a result of increased watercraft activity. Because no differences in rates of limb loss were found between males and females, limb loss probably results from aquatic encounters (i.e. limb loss does not appear to be the result of terrestrial predation during nesting). Furthermore, males experienced reduced body condition when injured, and terrapins with a major injury had lower survivorship than uninjured terrapins. 4.Therefore, in addition to reducing sources of mortality and protecting nesting habitat, measures to protect terrapins from watercraft activity may increase the survivorship of adult terrapins. Copyright © 2008 John Wiley & Sons, Ltd. [source] Estimate of the Area Affected Ecologically by the Road System in the United StatesCONSERVATION BIOLOGY, Issue 1 2000Richard T. T. Forman Two recent studies in The Netherlands and Massachusetts ( U.S.A.) evaluated several ecological effects of roads, including traffic noise effects, and provide quantitative evidence for a definable "road-effect zone." Based on the approximate width of this asymmetric convoluted zone, I estimate that about one-fifth of the U.S. land area is directly affected ecologically by the system of public roads. I identify a series of assumptions and variables suggesting that over time this preliminary estimate is more likely to rise than drop. Several transportation planning and policy recommendations, ranging from perforating the road barrier for wildlife crossings to closing certain roads, offer promise for reducing this enormous ecological effect. Resumen: En vista de un sistema carretero extensivo, un abundante y creciente tráfico vehicular y una literatura dispersa indicando que algunos efectos ecológicos de las carreteras se extienden más allá de 100 m, parece probable que los efectos ecológicos acumulativos del sistema carretero en los Estados Unidos es considerable. Dos estudios recientes en los Países Bajos y Massachusetts ( USA) evaluaron diversos efectos ecológicos de las carreteras, incluyendo efectos del ruido del tráfico y proporcionan evidencia cuantitativa para una definible "zona de efecto carretero". En base a la amplitud aproximada de esta zona conpleja y asimétrica, estimé que alrededor de una auinta parte del área terrestre de los Estados Unidos es directamente afectada ecológicamente por el sistema de carreteras públicas. Identifiqué series de conjeturas y variables que surgieren que a lo largo del tiempo esta estimación preliminar es mas probable que incremente a que disminuya. Diversos planes de transportación y recomendaciones políticas, que van desde perforar la barrera carretera para propiciar el cruce de vida silvestre hasta el cierre de ciertas carreteras ofrecen la promesa de reducir este efecto carretero. [source] Temperate marine reserves: global ecological effects and guidelines for future networksCONSERVATION LETTERS, Issue 6 2009Gavin B. Stewart Abstract Marine reserves, areas closed to all fishing and other extractive activities, provide a refuge for species of commercial and conservation importance. Given the considerable resources committed to designing temperate reserve networks, we synthesized data from temperate reserves worldwide to determine their ecological effects. In common with other studies, we found higher density, biomass, and species richness in temperate marine reserves compared to adjacent exploited areas. However, there was considerable heterogeneity in magnitude of effect among reserves, variability which was largely unexplained by species or reserve characteristics. Our analytical approach allowed for formal power analyses, indicating that detection of large reserve effects in temperate systems globally requires monitoring at least 37 reserves. These results must be qualified by the limitations of data available and will undoubtedly vary at different spatio-temporal scales and for different focal species, but provide guidance for the design and monitoring of future marine conservations plans. International commitments toward establishment of multiple reserves offer a unique opportunity to assess reserve effectiveness; this opportunity can only be realized if reserves are designed to achieve clear and quantifiable objectives and are adequately monitored before and after establishment, based on appropriate power analyses, to assess how well those objectives are achieved. [source] Prairie dog presence affects occurrence patterns of disease vectors on small mammalsECOGRAPHY, Issue 5 2008R. Jory Brinkerhoff Wildlife disease is recognized as a burgeoning threat to imperiled species and aspects of host and vector community ecology have been shown to have significant effects on disease dynamics. The black-tailed prairie dog is a species of conservation concern that is highly susceptible to plague, a flea-transmitted disease. Prairie dogs (Cynomys) alter the grassland communities in which they exist and have been shown to affect populations of small rodents, which are purported disease reservoirs. To explore potential ecological effects of black-tailed prairie dogs on plague dynamics, we quantified flea occurrence patterns on small mammals in the presence and absence of prairie dogs at 8 study areas across their geographic range. Small mammals sampled from prairie dog colonies showed significantly higher flea prevalence, flea abundance, and relative flea species richness than those sampled from off-colony sites. Successful plague transmission likely is dependent on high prevalence and abundance of fleas that can serve as competent vectors. Prairie dogs may therefore facilitate the maintenance of plague by increasing flea occurrence on potential plague reservoir species. Our data demonstrate the previously unreported ecological influence of prairie dogs on vector species assemblages, which could influence disease dynamics. [source] Effects of aphids on foliar foraging by Argentine ants and the resulting effects on other arthropodsECOLOGICAL ENTOMOLOGY, Issue 1 2008CRYSTAL D. GROVER Abstract 1.,Although interactions between ants and honeydew-producing insects have received considerable study, relatively little is known about how these interactions alter the behaviour of ants in ways that affect other arthropods. In this study, field and greenhouse experiments were performed that examined how the presence of aphids (Aphis fabae solanella) on Solanum nigrum influenced the foraging behaviour of Argentine ants (Linepithema humile) and, in turn, modified the extent to which ants deter larval lacewings (Chrysoperla rufilabris), which are known aphid predators. 2.,A field experiment demonstrated that the level of foliar foraging by ants increased linearly with aphid abundance, whereas no relationship existed between the level of ground foraging by ants and aphid abundance. 3.,In the greenhouse, as in the field, foliar foraging by ants greatly increased when aphids were present. Higher levels of foliar foraging led to a twofold increase in the likelihood that ants contacted aphid predators. As a result of these increased encounters with ants, lacewing larvae were twice as likely to be removed from plants with aphids compared with plants without aphids. Once contact was made, however, the behaviour of ants towards lacewing larvae appeared similar between the two experimental groups. 4.,Argentine ants drive away or prey upon a diversity of arthropod predators and parasitoids, but they also exhibit aggression towards certain herbivores. Future work should attempt to quantify how the ecological effects that result from interactions between honeydew-producing insects and invasive ants, such as L. humile, differ from those that result from interactions between honeydew-producing insects and native ants. [source] Fishing out marine parasites?ECOLOGY LETTERS, Issue 6 2010Impacts of fishing on rates of parasitism in the ocean Ecology Letters (2010) 13: 761,775 Abstract Among anthropogenic effects on the ocean, fishing is one of the most pervasive and extends deepest into the past. Because fishing reduces the density of fish (reducing transmission efficiency of directly transmitted parasites), selectively removes large fish (which tend to carry more parasites than small fish), and reduces food web complexity (reducing transmission efficiency of trophically transmitted parasites), the removal of fish from the world's oceans over the course of hundreds of years may be driving a long-term, global decline in fish parasites. There has been growing recognition in recent years that parasites are a critical part of biodiversity and that their loss could substantially alter ecosystem function. Such a loss may be among the last major ecological effects of industrial fishing to be recognized by scientists. [source] Mixed biodiversity benefits of agri-environment schemes in five European countriesECOLOGY LETTERS, Issue 3 2006D. Kleijn Abstract Agri-environment schemes are an increasingly important tool for the maintenance and restoration of farmland biodiversity in Europe but their ecological effects are poorly known. Scheme design is partly based on non-ecological considerations and poses important restrictions on evaluation studies. We describe a robust approach to evaluate agri-environment schemes and use it to evaluate the biodiversity effects of agri-environment schemes in five European countries. We compared species density of vascular plants, birds, bees, grasshoppers and crickets, and spiders on 202 paired fields, one with an agri-environment scheme, the other conventionally managed. In all countries, agri-environment schemes had marginal to moderately positive effects on biodiversity. However, uncommon species benefited in only two of five countries and species listed in Red Data Books rarely benefited from agri-environment schemes. Scheme objectives may need to differentiate between biodiversity of common species that can be enhanced with relatively simple modifications in farming practices and diversity or abundance of endangered species which require more elaborate conservation measures. [source] The extrapolation problem and how population modeling can help,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2008Valery E. Forbes Abstract We argue that population modeling can add value to ecological risk assessment by reducing uncertainty when extrapolating from ecotoxicological observations to relevant ecological effects. We review other methods of extrapolation, ranging from application factors to species sensitivity distributions to suborganismal (biomarker and "-omics") responses to quantitative structure,activity relationships and model ecosystems, drawing attention to the limitations of each. We suggest a simple classification of population models and critically examine each model in an extrapolation context. We conclude that population models have the potential for adding value to ecological risk assessment by incorporating better understanding of the links between individual responses and population size and structure and by incorporating greater levels of ecological complexity. A number of issues, however, need to be addressed before such models are likely to become more widely used. In a science context, these involve challenges in parameterization, questions about appropriate levels of complexity, issues concerning how specific or general the models need to be, and the extent to which interactions through competition and trophic relationships can be easily incorporated. [source] Examining the single and interactive effects of three insecticides on amphibian metamorphosis,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2008Michelle D. Boone Abstract Although aquatic communities frequently are exposed to a number of pesticides, the effects of chemical mixtures are not well understood. In two separate studies, I examined how insecticide mixtures influenced the likelihood of unpredictable, nonadditive effects on American toad (Bufo americanus) and green frog (Rana clamitans) tadpoles reared in outdoor aquatic communities. I exposed tadpoles to single or multiple insecticides at approximately half the reported median lethal concentrations using insecticides that were either acetylcholinesterase inhibitors (carbaryl or malathion) or a sodium-channel disruptor (permethrin). I found that combinations of insecticides with the same mode of action were more likely to have nonadditive effects on amphibian metamorphosis compared with those having different modes of action. Additionally, in one study, a commercial formulation of permethrin led to near-complete elimination of American toads, suggesting that this formulation could have adverse effects on aquatic communities. Many community studies exploring the ecological effects of expected environmental concentrations of pesticides have suggested that indirect effects in the food web, rather than direct effects on individual physiology, have the largest effect on amphibians. The present study indicates that direct effects of pesticides may become particularly important when insecticides with the same mode of action are present in the environment. [source] In situ on-line toxicity biomonitoring in water: Recent developmentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2006Almut Gerhardt Abstract ,In situ on-line biomonitoring is an emerging branch of aquatic biomonitoring. On-line biomonitoring systems use behavioral and/or physiological stress responses of caged test organisms exposed in situ either in a bypass system or directly instream. Sudden pollution waves are detected by several existing single-species on-line biomonitors, which until now have been placed mostly in streamside laboratories. However, recent achievements have been multispecies biomonitors, mobile biomonitors for direct in-stream use, development of new instruments, new methods for data analysis and alarm generation, biomonitors for use in soil and sediment, and scientific research supporting responses as seen in on-line biomonitors by linking them to other biological and ecological effects. Mobile on-line monitoring platforms containing an array of biomonitors, biosensors, and chemical monitoring equipment might be the future trend, especially in monitoring transboundary rivers at country borders as well as in coastal zones. [source] From organisms to populations: Modeling aquatic toxicity data across two levels of biological organizationENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2006Sandy Raimondo Abstract A critical step in estimating the ecological effects of a toxicant is extrapolating organism-level response data across higher levels of biological organization. In the present study, the organism-to-population link is made for the mysid, Americamysis bahia, exposed to a range of concentrations of six toxicants. Organism-level responses observed were categorized as no effect, delayed reproduction, reduced overall reproduction, or both reduced overall reproduction and survival. Population multiplication rates of each toxicant concentration were obtained from matrix models developed from organism-level endpoints and placed into the four categories of organism-level responses. Rates within each category were compared with growth rates modeled for control populations. Population multiplication rates were significantly less than control growth rates only for concentrations at which overall reproduction and both reproduction and survival were significantly less than the control values on the organism level. Decomposition analysis of the significant population-level effects identified reduced reproduction as the primary contributor to a reduced population multiplication rate at all sublethal concentrations and most lethal concentrations. Mortality was the primary contributor to reduced population growth rate only when survival was less than 25% of control survival. These results suggest the importance of altered reproduction in population-level risk assessment and emphasizes the need for complete life-cycle test data to make an explicit link between the organism and population levels. [source] Guidelines for developing and using quantitative structure-activity relationshipsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2003John D. Walker Abstract Numerous quantitative structure-activity relationships (QSARs) have been developed to predict properties, fate, and effects of mostly discrete organic chemicals. As the demand for different types of regulatory testing increases and the cost of experimental testing escalates, there is a need to evaluate the use of QSARs and provide some guidance to avoid their misuse, especially as QSARs are being considered for regulatory purposes. This paper provides some guidelines that will promote the proper development and use of QSARs. While this paper uses examples of QSARs to predict toxicity, the proposed guidelines are applicable to QSARs used to predict physical or chemical properties, environmental fate, ecological effects and health effects. [source] Unnatural landscapes in ecology: generating the spatial distribution of brine spills,ENVIRONMETRICS, Issue 7 2005Henriette I. Jager Abstract Quantitative tools are needed to evaluate the ecological effects of increasing petroleum production. In this article, we describe two stochastic models for simulating the spatial distribution of brine spills on a landscape. One model uses general assumptions about the spatial arrangement of spills and their sizes; the second model distributes spills by siting rectangular well complexes and conditioning spill probabilities on the configuration of pipes. We present maps of landscapes with spills produced by the two methods and compare the ability of the models to reproduce a specified spill area. A strength of the models presented here is their ability to extrapolate from the existing landscape to simulate landscapes with a higher (or lower) density of oil wells. Published in 2005 by John Wiley & Sons, Ltd. [source] Coupling long-term studies with meta-analysis to investigate impacts of non-native crayfish on zoobenthic communitiesFRESHWATER BIOLOGY, Issue 2 2006JULIA M. MCCARTHY Summary 1. Biological invasions are widely recognised as a significant component of human-caused environmental change and a primary threat to native biodiversity. The negative impacts of species invasions are particularly evident for freshwater crayfish faunas. 2. This study provides novel insight into the ecological effects of native and non-native crayfish on zoobenthic communities (with emphasis on the non-native rusty crayfish, Orconectes rusticus) across broad scales by combining a meta-analysis of small-scale experimental studies with a long-term observational study conducted over a 24 year period in Sparkling Lake, Wisconsin, U.S.A. (46°00,N, 89°42,W). 3. The meta-analysis summarised quantitatively the results of cage experiments for seven species of crayfish spanning four continents. We found that total zoobenthos densities (primarily Gastropoda and Diptera) were significantly lower in treatments containing crayfish relative to controls; a result that was significant for non-native crayfish but not for crayfish in their native range, perhaps owing to a small sample size. In contrast to other species, rusty crayfish were also negatively associated with Ephemeroptera. 4. Results from the time series analysis comparing temporal trends in rusty crayfish and invertebrate abundances from Sparkling Lake were consistent with the findings from the meta-analysis. Rusty crayfish were negatively correlated with the abundance of total zoobenthos, Diptera, Ephemeroptera and Odonata, as well as families of Trichoptera. 5. By coupling the results from short and long-term research, our study offers greater insight into the nature of crayfish-invertebrate interactions in aquatic systems, revealing consistent effects of invasive crayfish on native fauna. The control and management of invasive species is facilitated by the knowledge that well executed small-scale studies may be extrapolated to understand larger-scale ecological interactions. [source] Alkaloids may not be responsible for endophyte-associated reductions in tall fescue decomposition ratesFUNCTIONAL ECOLOGY, Issue 2 2010Jacob A. Siegrist Summary 1. ,Fungal endophyte , grass symbioses can have dramatic ecological effects, altering individual plant physiology, plant and animal community structure and function, and ecosystem processes such as litter decomposition and nutrient cycling. 2. ,Within the tall fescue (Schedonorus arundinaceus) , fungal endophyte (Neotyphodium coenophialum) symbiosis, fungal produced alkaloids are often invoked as the putative mechanism driving these ecological responses. Yet few measurements of alkaloids exist in the ecological literature. In this study, we quantified alkaloid levels in live, standing dead and decomposing endophyte-infected (E+) and ,free (E,) plant material and simultaneously evaluated the direct and indirect effects of endophyte presence on tall fescue decomposition. 3. ,Loline and ergot alkaloid levels were consistently high in live E+ (common toxic strain of N. coenophialum) tall fescue biomass throughout the sampling period (May,November 2007), whereas, E, live and standing dead material had non-detectable alkaloid concentrations. Standing dead E+ biomass had significantly reduced alkaloid levels (6,19x lower than the levels measured in the corresponding live E+ biomass) that were equivalent to E, live and dead for loline but were still somewhat higher than E, material for ergots. 4. ,In an effort to test the role of alkaloids in directly inhibiting decomposition, as has been suggested by previous studies, we conducted a litter bag experiment using green, alkaloid-laden E+ and alkaloid-free E, tall fescue plant material. We incubated E+ and E, litter bags in both E+ and E, tall fescue stands for 170 days, and measured mass loss, carbon and nitrogen content, and ergot and loline alkaloid concentrations over the incubation period. 5. ,Consistent with previous reports, both direct and indirect effects of endophyte presence on litter decomposition were observed: endophyte presence in the litter and surrounding microenvironment significantly reduced decomposition rates. Surprisingly, despite large differences in alkaloid content between E+ and E, litter from Day 0,Day 21 of the incubation, direct effects of the endophyte on litter decomposition, while significant, were relatively small (differences in mass loss between E+ and E, litter were never >3%). Alkaloids were gone from E+ material by day 56. 6. ,We propose that results from this study indicating alkaloids are largely absent in standing dead material (the typical input to the decomposition process), and that despite being present in our litter bag experiment, failed to produce large differences in mass loss between E+ and E, material questions the supposition that fungal produced alkaloids directly inhibit decomposition. Additional studies exploring the mechanisms behind the direct and indirect effects of endophytes on this ecosystem process are needed. [source] Geographical variation in the size of body organs in seabirdsFUNCTIONAL ECOLOGY, Issue 3 2000G. M. Hilton Abstract 1.,The size of body organs shows adaptive temporal variation in many animal species. The variation in the size of body organs was examined to see if it is also a component of local adaptation to geographical variation in ecological conditions. 2.,Major body organs were measured in five species of Icelandic seabirds, sampled from two areas where birds experience slightly different ecological conditions. Between-area differences in ecological conditions were consistent among the study species, allowing tests of the generality of ecological effects on organ size. 3.,All major body organs showed geographical size variation. Livers and kidneys were larger in locations where daily energy expenditure was expected to be higher; small intestines were heavier where food was of lower energy density; stomachs were heavier where food was less digestible; heart and flight muscle were larger where flight costs were greater. 4.,It is concluded that adaptive variation in organ size may be an important means by which animals optimize exploitation of their local environment, and may be a proximate factor in intraspecific life-history and metabolic variations between geographically separate populations. [source] Predicting population consequences of ocean climate change for an ecosystem sentinel, the seabird Cassin's aukletGLOBAL CHANGE BIOLOGY, Issue 7 2010SHAYE G. WOLF Abstract Forecasting the ecological effects of climate change on marine species is critical for informing greenhouse gas mitigation targets and developing marine conservation strategies that remain effective and increase species' resilience under changing climate conditions. Highly productive coastal upwelling systems are predicted to experience substantial effects from climate change, making them priorities for ecological forecasting. We used a population modeling approach to examine the consequences of ocean climate change in the California Current upwelling ecosystem on the population growth rate of the planktivorous seabird Cassin's auklet (Ptychoramphus aleuticus), a demographically sensitive indicator of marine climate change. We use future climate projections for sea surface temperature and upwelling intensity from a regional climate model to forecast changes in the population growth rate of the auklet population at the important Farallon Island colony in central California. Our study projected that the auklet population growth rate will experience an absolute decline of 11,45% by the end of the century, placing this population on a trajectory toward extinction. In addition, future changes in upwelling intensity and timing of peak upwelling are likely to vary across auklet foraging regions in the California Current Ecosystem (CCE), producing a mosaic of climate conditions and ecological impacts across the auklet range. Overall, the Farallon Island Cassin's auklet population has been declining during recent decades, and ocean climate change in this century under a mid-level emissions scenario is projected to accelerate this decline, leading toward population extinction. Because our study species has proven to be a sensitive indicator of oceanographic conditions in the CCE and a powerful predictor of the abundance of other important predators (i.e. salmon), the significant impacts we predicted for the Cassin's auklet provide insights into the consequences that ocean climate change may have for other plankton predators in this system. [source] Lagged effects of North Atlantic Oscillation on spittlebug Philaenus spumarius (Homoptera) abundance and survivalGLOBAL CHANGE BIOLOGY, Issue 12 2006ANTTI HALKKA Abstract The North Atlantic Oscillation (NAO) is a large-scale pattern of climate variability that has been shown to have important ecological effects on a wide spectrum of taxa. Studies on terrestrial invertebrates are, however, lacking. We studied climate-connected causes of changes in population sizes in island populations of the spittlebug Philaenus spumarius (L.) (Homoptera). Three populations living in meadows on small Baltic Sea islands were investigated during the years 1970,2005 in Tvärminne archipelago, southern Finland. A separate analysis was done on the effects of NAO and local climate variables on spittlebug survival in 1969,1978, for which survival data existed for two islands. We studied survival at two stages of the life cycle: growth rate from females to next year's instars (probably mostly related to overwintering egg survival), and survival from third instar stage to adult. The latter is connected to mortality caused by desiccation of plants and spittle masses. Higher winter NAO values were consistently associated with smaller population sizes on all three islands. Local climate variables entering the most parsimonious autoregressive models of population abundance were April and May mean temperature, May precipitation, an index of May humidity, and mean temperature of the coldest month of the previous winter. High winter NAO values had a clear negative effect on late instar survival in 1969,1978. Even May,June humidity and mean temperature of the coldest month were associated with late instar survival. The climate variables studied (including NAO) had no effect on the growth rate from females to next year's instars. NAO probably affected the populations primarily in late spring. Cold and snowy winters contribute to later snow melt and greater spring humidity in the meadows. We show that winter NAO has a considerable lagged effect on April and May temperature; even this second lagged effect contributes to differences in humidity. The lagged effect of the winter NAO to spring temperatures covers a large area in northern Europe and has been relatively stationary for 100 years at least in the Baltic area. [source] In situ-based effects measures: Determining the ecological relevance of measured responsesINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 2 2007Donald J Baird Abstract The aim of this review is to examine how the choice of test species and study design employed in the use of in situ approaches in ecological risk assessment can maximize the ecological relevance of data. We provide a framework to define and assess ecological relevance that permits study designs to remain focused on the ecological question being addressed. This framework makes explicit the linkages between effects at lower levels of biological organization and higher-order ecological effects at the population, community, and ecosystem levels. The usefulness of this framework is illustrated by reference to specific examples from aquatic ecotoxicology. The use of models as both interpretive and predictive tools is discussed, with suggestions of appropriate methods for different protection goals. [source] Rethinking the interface between ecology and society.JOURNAL OF APPLIED ECOLOGY, Issue 1 2008The case of the cockle controversy in the Dutch Wadden Sea Summary 1Applied ecology, like conservation research, may deal with societal issues if its scientifically based interventions have societal consequences. Human utilization plays a significant role in many ecosystems, so conservation ecologists often have to act on the interface between science and society, where controversies may arise. 2Using insights from science and technology studies, we have analysed the 15-year controversy on the ecological effects of cockle fishing in the Dutch Wadden Sea, which began around 1990 and involved nature protection and shellfish organizations, as well as several leading Dutch ecologists, in a heated debate. 3During this controversy, evaluative research on the ecological effects of cockle fishing was undertaken by a consortium of institutes in order to contribute to the process of political decision-making by the Dutch government on cockle fishery in this area. In addition to conservational and commercial interests, ecological research itself became part of the controversy. 4The research projects on the effects of cockle fishing during this controversy are examples of societally contextualized science, implying that interests and societal disputes are intertwined with scientific arguments. We have applied a dynamic model of contextualization in which societal stakes and scientific uncertainty are considered as the main factors determining the different contexts in which conservation research functions. 5Synthesis and applications. Conservation research, whether it is fundamental or managerially orientated, is related to greater societal aims and interests and might easily face more or less complex societally contextualized situations. Such situations imply extended responsibilities for scientists. Not only is there a need for sound science, but also for a sound way of interacting and communicating with the societal environment. Some elements of such a notion of extended accountability are presented. [source] Assessing and predicting the relative ecological impacts of disturbance on habitats with different sensitivitiesJOURNAL OF APPLIED ECOLOGY, Issue 2 2007J. G. HIDDINK Summary 1Methods for assessing habitat sensitivity to human impacts are needed to gauge the sustainability of existing impacts, develop spatial management plans and support meaningful environmental impact assessments. These methods should be quantitative, validated, repeatable and applicable at the scales of impact and management. 2Existing methods for assessing the sensitivity of marine habitats to human impacts have tended to rely on expert judgement and/or scoring systems. They are neither validated, quantitative nor repeatable. 3We have developed a method that meets the criteria for assessing the sensitivity of seabed habitats to physical disturbance, and delineating and mapping habitat sensitivity at large spatial scales (>105 km2). The method assumes that sensitivity is related to the recovery time of production or biomass, as predicted using a size-based model that takes account of the effects of natural disturbance. 4As trawling disturbance is a major and widespread direct human impact on shelf seas, this was used as an example of anthropogenic physical disturbance. We mapped habitat sensitivity to trawling in 9-km2 boxes across an area of 125 000 km2 in the North Sea. 5Habitat sensitivities varied widely, and a trawling frequency of 5 year,1 in the least-sensitive habitat had the same ecological effect as a trawling frequency of 0·3 year,1 in the most-sensitive habitat (based on production). When trawling effort was held constant but redirected to the least-sensitive habitats, the existing impacts on production and biomass were reduced by 36% and 25%, respectively. 6Synthesis and applications. The method described in this paper enables managers to predict the implications of changing patterns of human impact on seabed habitats when establishing spatial management plans. In the context of fisheries management, this will support the identification and selection of fishing grounds that minimize the adverse ecological effects of fishing; the selection of closed areas (both representative and highly sensitive); the comparison of management options that might reduce the overall environmental impacts of fishing; and any future steps towards the application of environmental impact assessment in advance of fishery development. [source] Effects of Bt-toxin Cry1Ac on Propylaea japonica Thunberg (Col., Coccinellidae) by feeding on Bt-treated Bt-resistant Helicoverpa armigera (Hübner) (Lep., Noctuidae) larvaeJOURNAL OF APPLIED ENTOMOLOGY, Issue 4 2006S.-Y. Zhang Abstract:,Propylaea japonica is an important predatory insect of common cotton pests. To assess the ecological effects of transgenic Bt cotton, expressing Cry1Ac toxin, on this predator, we examined the life history parameters of P. japonica for two generations by feeding them with Bt-resistant Helicoverpa armigera. After ingesting Bt-treated Bt-resistant H. armigera larvae in the third and fourth instar, the body mass and body length of adult P. japonica decreased, a combined effect of poor prey quality and Cry1Ac Bt-toxin may account for these effects. However, larval survivorship and development in these two instars, pupal mortality, fecundity and adult longevity of P. japonica were not affected in both the generations. These results suggest that ingesting Bt-toxin Cry1Ac-treated pests in advanced larval stage might have no significant effect on the fitness of predator P. japonica. [source] Instream Flow Science For Sustainable River Management,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 5 2009Geoffrey E Petts Abstract:, Concerns for water resources have inspired research developments to determine the ecological effects of water withdrawals from rivers and flow regulation below dams, and to advance tools for determining the flows required to sustain healthy riverine ecosystems. This paper reviews the advances of this environmental flows science over the past 30 years since the introduction of the Instream Flow Incremental Methodology. Its central component, Physical HABitat SIMulation, has had a global impact, internationalizing the e-flows agenda and promoting new science. A global imperative to set e-flows, including an emerging trend to set standards at the regional scale, has led to developments of hydrological and hydraulic approaches but expert judgment remains a critical element of the complex decision-making process around water allocations. It is widely accepted that river ecosystems are dependent upon the natural variability of flow (the flow regime) that is typical of each hydro-climatic region and upon the range of habitats found within each channel type within each region. But as the sophistication of physical (hydrological and hydraulic) models has advanced emerging biological evidence to support those assumptions has been limited. Empirical studies have been important to validate instream flow recommendations but they have not generated transferable relationships because of the complex nature of biological responses to hydrological change that must be evaluated over decadal time-scales. New models are needed to incorporate our evolving knowledge of climate cycles and morphological sequences of channel development but most importantly we need long-term research involving both physical scientists and biologists to develop new models of population dynamics that will advance the biological basis for 21st Century e-flow science. [source] | ||||||||||||||||||||||||||||||||||