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1.
SYNOPSIS. North America's Great Lakes have recently been invadedby two genetically and morphologically distinct species of Dreissena.The zebra mussel (Dreissena polymorpha) became established inLake St. Clair of the Laurentian Great Lakes in 1986 and spreadthroughout eastern North America. The second dreissenid, termedthe quagga mussel, has been identified as Dreissena bugensisAndrusov, 1897. The quagga occurs in the Dnieper River drainageof Ukraine and now in the lower Great Lakes of North America.In the Dnieper River, populations of D. polymorpha have beenlargely replaced by D. bugensis; anecdotal evidence indicatesthat similar trends may be occurring in the lower LaurentianGreat Lakes. Dreissena bugensis occurs as deep as 130 m in theGreat Lakes, but in Ukraine is known from only 0–28 m.Dreissena bugensis is more abundant than D. polymorpha in deeperwaters in Dneiper River reservoirs. The conclusion that NorthAmerican quagga mussels have a lower thermal maximum than zebramussels is not supported by observations made of populationsin Ukraine. In the Dnieper River drainage, quagga mussels areless tolerant of salinity than zebra mussels, yet both dreissenidshave acclimated to salinities higher than North American populations;eventual colonization into estuarine and coastal areas of NorthAmerica cannot be ignored.  相似文献   

2.
Source–sink dynamics may be ubiquitous in ecology. We developed a theory for source–sink dynamics using spatial extensions of the net reproductive value, R 0, which has been used elsewhere to define fitness, disease eradication, population growth, and invasion risk. R 0 decomposes into biologically meaningful components—lifetime reproductive output, survival, and dispersal—that are widely adaptable and easily interpreted. The theory provides a general quantitative means for relating fundamental niche, biotic interactions, dispersal, and species distributions. We applied the methods to Dreissena and found a resolution to a paradox in invasion biology—competitive coexistence between quagga (Dreissena bugensis) and zebra (D. polymorpha) mussels among lakes despite extensive niche overlap within lakes. Source–sink dynamics within lakes between deepwater and shallow habitats, which favor quagga and zebra mussels, respectively, yield a metacommunity distribution where quagga mussels dominate large lakes and zebra mussels dominate small lakes. The source–sink framework may also be useful in spatial competition theory, habitat conservation, marine protected areas, and ecological responses to climate change.  相似文献   

3.
This study tests population genetic patterns across the Eurasian dreissenid mussel invasions of North America—encompassing the zebra mussel Dreissena polymorpha (1986 detection) and the quagga mussel D. rostriformis bugensis (detected in 1990, which now has largely displaced the former in the Great Lakes). We evaluate their source-spread relationships and invasion genetics using 9–11 nuclear microsatellite loci for 583 zebra mussels (21 sites) and 269 quagga mussels (12 sites) from Eurasian and North American range locations, with the latter including the Great Lakes, Mississippi River basin, Atlantic coastal waterways, Colorado River system, and California reservoirs. Additionally, mtDNA cytochrome b gene sequences are used to verify species identity. Our results indicate that North American zebra mussels originate from multiple non-native northern European populations, whereas North American quagga mussels trace to native estuaries in the Southern Bug and Dnieper Rivers. Invasive populations of both species show considerable genetic diversity and structure (zebra F ST = 0.006–0.263, quagga F ST = 0.008–0.267), without founder effects. Most newer zebra mussel populations have appreciable genetic diversity, whereas quagga mussel populations from the Colorado River and California show some founder effects. The population genetic composition of both species changed over time at given sites; with some adding alleles from adjacent populations, some losing them, and all retaining closest similarity to their original composition. Zebra mussels from Kansas and California appear genetically similar and assign to a possible origin from the St. Lawrence River, whereas quagga mussels from Nevada and California assign to a possible origin from Lake Ontario. These assignments suggest that overland colonization pathways via recreational boats do not necessarily reflect the most proximate connections. In conclusion, our microsatellite results comprise a valuable baseline for resolving present and future dreissenid mussel invasion pathways.  相似文献   

4.
5.
SYNOPSIS. Since the discovery of the zebra mussel, Dreissenapolymorpha, in the Great Lakes in 1988 comparisons have beenmade with mussel populations in Europe and the former SovietUnion. These comparisons include: Population dynamics, growthand mortality rates, ecological tolerances and requirements,dispersal rates and patterns, and ecological impacts. NorthAmerican studies, mostly on the zebra mussel and a few on asecond introduced species, the quagga mussel, Dreissena bugensis,have revealed some similarities and some differences. To dateit appears that North American populations of zebra musselsare similar to European populations in their basic biologicalcharacteristics, population growth and mortality rates, anddispersal mechanisms and rates. Relative to European populationsdifferences have been demonstrated for: (1) individual growthrates; (2) life spans; (3) calcium and pH tolerances and requirements;(4) potential distribution limits; and (5) population densitiesof veligers and adults. In addition, studies on the occurrenceof the two dreissenid species in the Great Lakes are showingdifferences in their modes of life, depth distributions, andgrowth rates. As both species spread throughout North America,comparisons between species and waterbodies will enhance ourability to more effectively control these troublesome species.  相似文献   

6.
Nonindigenous species may exert strong effects on ecosystem structure and function. The zebra mussel (Dreissena polymorpha) has been attributed with profound changes in invaded ecosystems across eastern North America. We explored vertical profiles of water flow velocity and chlorophyll a concentration in western Lake Erie, over rocky substrates encrusted with Dreissena, to assess the extent to which mussels influence coupling between benthic and pelagic regions of the lake. Flow velocity was always low at surveyed sites (less than or equal to 2.9 cm s-1) and declined in direct proximity to the lakebed. Mean chlorophyll a concentration was also low (less than 5μg L-1) at all sites and depths. Chlorophyll a concentration was positively correlated with distance above lakebed and was lowest (0.3μg L-1) directly adjacent to the lakebed. Spatial patterns of zooplankton grazers could not explain observed vertical gradients in chlorophyll concentration. Hydrodynamic modeling revealed that filtering effects of Dreissena in a nonstratified, shallow basin depend mainly on upstream chlorophyll concentration, intensity of turbulent diffusion, feeding efficiency of the mussel colony, and the distance downstream from the leading edge of the mussel colony. In contrast to widespread perceptions that molluscs reduce phytoplankton concentration only adjacent to the lakebed, modeling scenarios indicated that depletion occurs throughout the water column. Depletion was, however, inversely proportional to distance above the lakebed. Simulation results are consistent with field-based observations made in shallow water habitats populated by large Dreissena populations in the Great Lakes and elsewhere. Results from this study indicate that zebra mussels strongly enhance coupling between pelagic and benthic regions in shallow lakes. Enhanced coupling between these regions explains, in part, high population densities of Dreissena and of many benthic invertebrates in ecosystems invaded by zebra mussels. Received 14 July 1998; accepted 25 March 1999.  相似文献   

7.
1. Non‐indigenous ecosystem engineers can substantially affect native biodiversity by transforming the physical structure of habitats. In the Great Lakes–St. Lawrence River system, introduced dreissenid mussels (Dreissena polymorpha and D. bugensis) and the native benthic macroalga Cladophora act as ecosystem engineers by increasing substratum complexity and providing interstitial habitat for benthic macroinvertebrates. 2. We manipulated the topography and perimeter‐to‐area ratio of patches of dreissenid mussels in a series of colonisation experiments conducted at two sites in the St. Lawrence River. Experimental substrata were variably colonised by Cladophora, prompting us to examine (i) how the topography of Dreissena patches affects benthic macroinvertebrate diversity and (ii) the extent to which the effects of Dreissena are altered by the presence of another habitat‐modifying organism (Cladophora). 3. The results of our first experiment suggested that a patchy distribution of dreissenid mussels is an important driver of benthic diversity at small spatial scales. The results of our second and third experiments suggested that a native habitat engineer, Cladophora, modifies the impact of Dreissena on benthic macroinvertebrate communities. 4. While macroalgal blooms have been linked to the large‐scale impacts of Dreissena on light and nutrient availability, Dreissena shells inhibited Cladophora growth at our experimental scale. These findings demonstrate that the interactions between habitat‐modifying species can complicate efforts to predict the community‐level effects of an invasion.  相似文献   

8.
Unexpected habitat innovations among invading species are illustrated by the expansion of dreissenid mussels across sedimentary environments in shallow water unlike the hard substrates where they are conventionally known. In this note, records of population characteristics of invading zebra (Dreissena polymorpha) and quagga (Dreissena bugensis) mussels from 1994 through 1998 are reported from shallow (less than 20m) sedimentary habitats in western Lake Erie. Haphazard SCUBA collections of these invading species indicated that combined densities of zebra and quagga mussels ranged from 0 to 32,500 individuals per square meter between 1994 and 1998, with D. polymorpha comprising 75–100% of the assemblages. These mixed mussel populations, which were attached by byssal threads to each other and underlying sand-grain sediments, had size–frequency distributions that were typical of colonizing populations on hard substrates. Moreover, the presence of two mussel cohorts within the 1994 samples indicated that these species began expanding onto soft substrates not later than 1992, within 4 years of their initial invasion in western Lake Erie. Such historical data provide baselines for interpreting adaptive innovations, ecological interactions and habitat shifts among the two invading dreissenid mussel species in North America.  相似文献   

9.
1. Suspension feeding by bivalves exceeds that by other planktivores in many North American rivers, and food webs may be altered substantially by differences in feeding patterns between native unionid mussels and invading dreissenid mussels. 2. We conducted an experiment comparing zooplanktivory by one unionid and two dreissenid species that addressed several primary questions. Is benthic planktivory important in this river? Has this linkage been altered substantially by dreissenids? Do the two dreissenid species differ in planktivory, and is this ecologically important if quagga mussels extend their geographical range? 3. Our 12‐day experiment consisted of controls (no mussels) and treatments with unionid (Elliptio complanata), quagga (Dreissena bugensis) or zebra (D. polymorpha) mussels in 3500‐L, 80‐μm mesh enclosures placed in a slackwater area of the St Lawrence River. 4. The density of the most abundant calanoid copepod Eurytemora affinis increased in the presence of dreissenids, probably as an indirect food web response. By day 12, a cumulative effect was shown by the most overwhelmingly abundant rotifer, Polyarthra, whose density declined dramatically in dreissenid enclosures compared with control and unionid enclosures. Rotifer densities in unionid enclosures were not different from controls, nor were dreissenid treatments different from each other. The effects on rotifers were probably from predation, as Chl‐a did not vary among treatments. 5. We conclude that benthic‐pelagic coupling via planktivory is important in slackwater areas. Dreissenids have strengthened this linkage, but range extension of quaggas should not appreciably alter effects produced by a similar biomass of zebra mussels.  相似文献   

10.
Colony forming and toxic cyanobacteria form a problem in surfacewaters of shallow lakes, both for recreation and wildlife. Zebramussels, Dreissena polymorpha, have been employed to help torestore shallow lakes in the Netherlands, dominated by cyanobacteria,to their former clear state. Zebra mussels have been presentin these lakes since they were created in the 19th century bythe excavation of peat and are usually not considered to bean invasive species. Most grazing experiments using Dreissenahave been performed with uni-cellular phytoplankton laboratorystrains and information on grazing of larger phytoplankton taxahardly exists. To gain more insight in to whether D. polymorphais indeed able to decrease cyanobacteria in the phytoplankton,we therefore performed grazing experiments with zebra musselsand two species of cyanobacteria, that greatly differ in shape:colony forming strains of Microcystis aeruginosa and the filamentousspecies Planktothrix agardhii. For both species a toxic anda non-toxic strain was selected. We found that zebra musselscleared toxic Planktothrix at a higher rate than non-toxic Planktothrix,toxic or non-toxic Microcystis. Clearance rates between theother strains were not significantly different. Both phytoplanktonspecies, regardless of toxicity, size and shape, were foundin equal amounts (based on chlorophyll concentrations) in theexcreted products of the mussels (pseudofaeces). The resultsshow that zebra mussels are capable of removing colonial andfilamentous cyanobacteria from the water, regardless of whetherthe cyanobacteria are toxic or not. This implies that the musselsmay be used as a biofilter for the removal of harmful cyanobacterialblooms in shallow (Dutch) lakes where the mussels are alreadypresent and not a nuisance. Providing more suitable substratefor zebra mussel attachment may lead to appropriate mussel densitiescapable of filtering large quantities of cyanobacteria.  相似文献   

11.
The paper includes data on species composition of chironomid larvae which were encountered in the mantle cavity of zebra mussels (Dreissena polymorpha) within 7 waterbodies in the Republic of Belarus. All were found to be free‐living species commonly present in periphyton and/or benthos. A long‐term study of the seasonal dynamics of these larvae in Dreissena did not reveal any typical pattern. Our data suppose that chironomids do not have an obligate association with zebra mussels and possibly enter their mantle cavity inadvertently. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

12.
1. Recent increases in phytoplankton biomass and the recurrence of cyanobacterial blooms in western Lake Erie, concomitant with a shift from a community dominated by zebra mussels (Dreissena polymorpha) to one dominated by quagga mussels (D. bugensis), led us to test for differences in ammonia‐nitrogen and phosphate‐phosphorus excretion rates of these two species of invasive molluscs. 2. We found significant differences in excretion rate both between size classes within a taxon and between taxa, with zebra mussels generally having greater nutrient excretion rates than quagga mussels. Combining measured excretion rates with measurements of mussel soft‐tissue dry weight and shell length, we developed nutrient excretion equations allowing estimation of nutrient excretion by dreissenids. 3. Comparing dreissenid ammonia and phosphate excretion with that of the crustacean zooplankton, we demonstrated that the mussels add to nitrogen and phosphorus remineralisation, shortening nitrogen and phosphorus turnover times, and, importantly, modify the nitrogen and phosphorus cycles in Lake Erie. The increased nutrient flux from dreissenids may facilitate phytoplankton growth and cyanobacterial blooms in well‐mixed and/or shallow areas of western Lake Erie.  相似文献   

13.
The production and use of polychlorinated biphenyls (PCBs) have been restricted in North America since the 1970s; yet, PCBs are still detected in all components of the Great Lakes ecosystems. Our objective was to determine how total PCB (PCBT) concentrations in spottail shiner (Notropis hudsonius) changed over the period 1975–2007 in the lower Great Lakes. Trends were best described by three basic models: (1) piecewise models where concentrations followed a decreasing trend before the break point (T) and an increasing trend post-T (Lake St. Clair, eastern Lake Erie, and upper Niagara River); (2) piecewise models where concentrations decreased both pre- and post-T but where the rate of decline post-T was less than that pre-T (western Lake Erie and Niagara River’s Tonawanda Channel); and (3) linear models where concentrations declined at a constant rate across the entire temporal range (lower Niagara River and western Lake Ontario). Piecewise models best described the trends in shallow areas that are susceptible to full water-column mixing whereas constant-slope models best described trends in deeper areas. For piecewise models, T typically occurred during the years 1988–1992. Two events coincided with this timing: (1) a sustained shift towards warming summer temperatures and (2) the proliferation of dreissenid mussels (Dreissena spp.). The weight-of-evidence suggests that the dreissenid invasions were a more likely driving factor behind the observed trends.  相似文献   

14.
Suppression of microzooplankton by zebra mussels: importance of mussel size   总被引:3,自引:0,他引:3  
1. The zebra mussel (Dreissena polymorpha) is amongst the most recent species to invade the Great Lakes. We explored the suppressive capabilities of mussels 6–22-mm in size on Lake St Clair microzooplankton (< 240)μm) in laboratory experiments. 2. Absolute suppression of rotifers and Dreissena veliger larvae was proportional to mussel shell length for individuals larger than 10 mm; larger zooplankton, mainly copepod nauplii and Cladocera, were not affected. Mussel clearance rates on rotifers generally exceeded those on veligers, although rates for both increased with increasing mussel size. Rotifer-based clearance rates of large (22 mm) mussels approached published values for phytoplankton food. 3. Most zooplankton taxa, particularly rotifers, declined significantly in western Lake Erie during the late 1980s concomitant with the establishment and population growth of zebra mussels in the basin. Densities of some taxa subsequently increased, although rotifers and copepod nauplii densities remained suppressed through 1993. Available evidence indicates that direct suppression by Dreissena coupled with food limitation provides the most parsimonious explanation for these patterns.  相似文献   

15.
1. Dreissenid mussels (quagga mussels, Dreissena bugensis, and zebra mussels, D. polymorpha) are invasive species that function as ecosystem engineers in the Laurentian Great Lakes. Dreissena are increasingly abundant on silt, sand and other soft substrates; by altering benthic habitat, these mussels can alter benthic community structure. 2. We used laboratory mesocosm experiments to examine the effects of soft‐sediment Dreissena clusters on the habitat preference of Hexagenia, a native burrowing mayfly that is an important food source to fish. We conducted three experiments to test whether Hexagenia: (1) select for bare sediment, soft sediment covered with live Dreissena (added structure and food resources) or soft sediment with clusters made of empty Dreissena shells (added structure only), (2) prefer a specific density of live Dreissena on soft sediment and (3) select for or avoid sediment with an accumulation of empty Dreissena shells. 3. Contrary to initial expectations, we found that Hexagenia selected for sediment covered with live Dreissena clusters, followed by empty Dreissena shells clusters, and lastly what was previously thought to be the preferred habitat, bare sediment. Not only did Hexagenia prefer Dreissena‐covered sediment, but they also preferred high densities of Dreissena. 4. We also experimentally tested the effects of Dreissena‐covered soft sediment on the availability of Hexagenia to fish. We had three treatment levels representing three distinct habitat types: (1) bare sediment (no Dreissena) treatment in which water was turbid because of mayfly activity, (2) Dreissena‐covered sediment treatment in which water was clear because of Dreissena filtration and (3) Dreissena‐covered sediment with added turbidity. We found that in low light conditions, similar to many locations where both organisms are found to co‐occur, both yellow perch and round goby consumption of Hexagenia significantly decreased when Dreissena covered the bottom sediment. 5. These results suggest that by choosing Dreissena‐covered habitat, Hexagenia receive protection from fish predation in turbid/low light systems. However, protection from predation cannot be the only reason Hexagenia select Dreissena‐covered sediments, as Hexagenia selected for live clusters more often than empty clusters and may be a result of additional food resources.  相似文献   

16.

The invasion of dreissenid mussels into inland waters of the Northern Hemisphere has received considerable attention and, both zebra mussels and quagga mussels continue to spread westward. Despite studies aimed at understanding the biology of dreissenid mussels, relatively few studies have focused on water velocity and other hydrodynamic characteristics of water flow. The objective of this review was to identify, through a search of online databases, the papers that have been made available that directly have assessed the influence of hydrodynamic characteristics of water flow on dreissenid mussel biology. Using Thompson Reuters Web of Science, Google Scholar, and other resources, 46 papers were identified. These papers detailed that metrics associated with hydrodynamics of water flow, including current, wave action, velocity, flow rate, and discharge, can influence the biology of dreissenid mussels (primarily zebra mussel, which were studied far more than quagga mussel). Hydrodynamic characteristics influenced external fertilization, larval development and settlement, juvenile recruitment and attachment, and suspension feeding, growth and abundance of adults. In most cases, the impact of higher flow rates were locally negative and may present an opportunity for applications of water flow to control the spread or establishment of dreissenid mussels. Several knowledge gaps have been identified.

  相似文献   

17.
The zebra mussel (Dreissena polymorpha) and its congener the quagga mussel (Dreissena rostriformis bugensis) are both invaders in freshwater, but have very different invasion histories, with zebra mussels attaining substantially faster rates of spread at virtually all spatial scales. However, in waterbodies where they co-occur, D. r. bugensis can displace D. polymorpha. To determine if the mechanisms for this displacement are associated with different survival and growth, we kept mussels in flow-through tanks for 289 days with two temperature regimes that mimicked the natural surface water (littoral zone) and hypolimnion conditions of Lake Erie. For the littoral zone regime, we used water directly from the surface of Lake Erie (range 4–25°C, average 11.9 ± 0.6°C). For the profundal zone treatment, Lake Erie surface water was chilled to about 6°C (range 5–8°C, average 6.2 ± 0.6°C) for the full duration of the experiment. For each of these temperature regimes, we used three replicate tanks with only zebra mussels present and three replicate tanks with only quagga mussels (150 ind./tank each), and three replicate tanks with both species (75 ind./tank of each species). Quagga mussels had higher survivorship and grew more than zebra mussels in all treatments. For both species, the size of the mussel entering the winter was critical for survivorship. Larger mussels had a higher survival over the winter in all treatments. For both species, there was a survivorship and growth tradeoff. In the warmer littoral zone treatment both species had higher growth, but lower survival than in the colder profundal zone treatment. Surprisingly, although quagga mussels outperformed zebra mussels, zebra mussel survivorship was better when they were faced with competition by quagga mussels than with just intraspecific competition. In addition, quagga mussels suffered size-specific mortality during the growing season only when facing interspecific competition with zebra mussels. Further experiments are needed to determine the possible mechanisms for these interspecific effects.  相似文献   

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Hugh J. MacIsaac 《Oecologia》1996,105(4):484-492
The zebra mussel Dreissena polymorpha was introduced to North America during the mid-1980s, and is now a dominant member of many benthic communities in the lower Great Lakes. In this study, I explored the abundance, biomass, size structure and settlement of Dreissena inhabiting rocks along a wave-swept disturbance gradient near Middle Sister Island in western Lake Erie. Ten rocks were collected from quadrats at six sites along each of three transect lines oriented perpendicular to shore. Occurrence, abundance and biomass of Dreissena on smaller, movable rocks were positively associated with rock distance from shore (lake depth) and with rock area; rocks at nearshore sites supported little, if any, Dreissena, whereas those at offshore sites were heavily colonized. Mussel size distributions also differed in relation to shore distance. Large mussels (19 mm) were underrepresented or absent on rocks collected at nearshore sites, but were overrepresented at offshore locations (37 m). Settlement of larval mussels on settling pads was positively correlated with distance offshore and with time of exposure, though settlement was substantial even at a nearshore (10 m) location. Area-adjusted mussel dry mass increased more rapidly with distance offshore on large than on small rocks. Large rocks also required more force to displace and were significantly less likely to be disturbed when transplanted at the study site. Results from this study indicate that occurrence, abundance and size structure of Dreissena in nearshore waters of Lake Erie correspond with the frequency of habitat disturbance, though other factors including food limitation and larval supply may also contribute to these patterns. These patterns complement studies that established the significance of physical disturbance in other aquatic systems.  相似文献   

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