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1.
  • 1 We conducted survey and transplant studies to determine whether colonization and residency on soft sediments by introduced, fouling mussels (Dreissena polymorpha and D. bugensis) were affected by physical disturbance, and whether Dreissena presence in turn influenced the diversity and population densities of other benthic invertebrates. Surveys revealed that colony density was typically higher at moderate depths than at shallower and greater ones. However, the largest, midsummer colonies and greatest coverage of sediments by mussels occurred at deeper sites.
  • 2 Disturbance of transplanted colonies varied by depth and colony size, with deeper and larger colonies experiencing the lowest destruction rates. Colony destruction rate was positively correlated with current velocity adjacent to the lakebed.
  • 3 Absence of mussel colonies at shallow sites was not determined by recruitment or substrate limitation, as recruit density was higher and sediment characteristics more suitable for postveliger settlement at shallow than at deeper sites. Rather, seasonal storms have much stronger effects in shallow than in deep water.
  • 4 Mussel residency on soft sediment has profound effects on invertebrate biodiversity. Invertebrate species (taxon) richness and total abundance were positively correlated with mussel colony area. Mussel‐sediment habitat supported between 462 and 703% more taxa, and between 202 and 335% more individuals (exclusive of Dreissena) than adjacent soft‐sediment lacking mussels.
  • 5 Results from this study illustrate that physical disturbance directly limits the distribution of mussels on soft sediments, and the diversity and abundance of other benthic invertebrates in consequence.
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2.
The impact of Dreissena polymorpha settlement on recruitment of juvenile mussels and density of other macroinvertebrates was studied in field experiments using blank concrete blocks and tiles (control), blocks and tiles with attached empty zebra mussel shells, and blocks and tiles with attached living mussels. On blocks, dominant invertebrate taxa showed colonization patterns coinciding with increased habitat complexity owing to zebra mussel settlement or the biodeposition of faeces and pseudofaeces. Adult and especially juvenile zebra mussels preferred blocks with empty shells to blank blocks and blocks with living mussels; this might possibly be caused by a chemical cue that induces gregarious settlement. Lower recruitment on blocks with attached living mussels compared to blocks with only shells could be the consequence of ingestion of larvae by adult mussels and of competition for food. On tiles, the sediments deposited and the organic content of the sediment were investigated. Sedimentation was significantly higher on shell‐only and live‐mussel tiles compared to blank tiles. Organic matter differed significantly between blank and live‐mussel tiles.  相似文献   

3.
Complex habitat structures can influence the foraging success of fish. Competition for food between fish species can therefore depend on the competitors' abilities to cope with structural complexity. In laboratory experiments, we comparatively assessed effects of zebra mussels (Dreissena polymorpha Pall .) on the foraging success of Eurasian perch (Perca fluviatilis L.) and ruffe (Gymnocephalus cernuus (L.)). In single‐species and mixed‐species experiments, the fish were fed caddisfly larvae (Tinodes waeneri (L.)) over complex (mussel‐covered stones) and less‐complex (bare stones) substrates. With intraspecific competition, food consumption by perch and ruffe decreased significantly when the complex substrate was used. With interspecific competition, food consumption by perch and ruffe did not change with substrate complexity, but perch clearly out‐competed ruffe on both substrates. Zebra mussel beds provide a refuge for macrozoobenthos against predation by ruffe and probably also by perch. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

4.
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   

5.
1. We asked whether unionid mussels influence the distribution and abundance of co‐occurring benthic algae and invertebrates. In a yearlong field enclosure experiment in a south‐central U.S. river, we examined the effects of living mussels versus sham mussels (shells filled with sand) on periphyton and invertebrates in both the surrounding sediment and on mussel shells. We also examined differences between two common unionid species, Actinonaias ligamentina (Lamarck 1819) and Amblema plicata (Say 1817). 2. Organic matter concentrations and invertebrate densities in the sediment surrounding mussels were significantly higher in treatments with live mussels than treatments with sham mussels or sediment alone. Organic matter was significantly higher in the sediment surrounding Actinonaias than that surrounding Amblema. Actinonaias was more active than Amblema and may have increased benthic organic matter through bioturbation. 3. Living mussels increased the abundance of periphyton on shells and the abundance and richness of invertebrates on shells, whereas effects of sham mussels were similar to sediment alone. Differences in the amount of periphyton growing on the shells of the two mussel species reflected differences in mussel activity and shell morphology. 4. Differences between living and sham mussel treatments indicate that biological activities of mussels provide ecosystem services to the benthic community beyond the physical habitat provided by shells alone. In treatments containing live mussels we found significant correlations between organic matter and chlorophyll a concentrations in the sediment, organic matter concentrations and invertebrate abundance in the sediment and the amount of chlorophyll a on the sediment and invertebrate abundance. There were no significant correlations among these response variables in control treatments. Thus, in addition to providing biogenic structure as habitat, mussels likely facilitate benthic invertebrates by altering the availability of resources (algae and organic matter) through nutrient excretion and biodeposition. 5. Effects of mussels on sediment and shell periphyton concentrations, organic matter concentrations and invertebrate abundance, varied seasonally, and were strongest in late summer during periods of low water volume, low flow, and high water temperature. 6. Our study demonstrates that freshwater mussels can strongly influence the co‐occurring benthic community, but that effects of mussels are context‐dependent and may vary among species.  相似文献   

6.
1. The importance of native freshwater mussels for ecosystem processes depends on their density, size distribution and activity. In lakes, many of the factors that affect mussels (fish hosts, habitat, food) could be directly or indirectly related to wind‐driven physical processes. 2. We tested whether the abundance and size of Elliptio complanata in the shallow, nearshore areas of a medium‐sized lake were related to site exposure, substratum type and fish distribution. To disentangle some of the correlated variables known to affect mussel distribution, we used paired exposed and sheltered sampling sites along the 7‐km fetch of the lake basin. 3. The distribution of sediment characteristics in nearshore areas was highly predictable. The mean depth of accumulated soft sediments decreased with increasing fetch at wind‐exposed sites, but increased with increasing fetch at sheltered sites. Sediments were deeper along the main shoreline than around islands. Deeper sediments tended to be finer and higher in silt content and organic fraction. 4. The density and proportion of juvenile mussels along the main shoreline varied in a unimodal way with sediment depth. These results suggest that wind‐driven physical forces affect the transport of young juveniles to sediment depositional areas and create sediment conditions that influence their growth and survival. In contrast, the proportion of juvenile mussels around islands was not related to sediment characteristics, but decreased with remoteness of the island, suggesting that the distribution of juvenile mussels may be limited by fish movements. These results are tentative since they do not include buried juvenile mussels. 5. We also found a unimodal relationship between total mussel density (juveniles and adults) and sediment depth but, in contrast to the relationship for juveniles only, it applied to all sites with soft sediments, including islands. We conclude that factors related to sediment depth affect the growth and survival of adult mussels around islands and that these factors are strong enough to modify the pattern of distribution established via dispersal during earlier life stages. 6. The mean shell length of adults at different sites within the lake basin ranged from 60 to 85 mm. Mussel shell length decreased with increasing fetch at sites exposed to the prevalent winds, but was relatively constant on the sheltered side of peninsulas and islands. The size of unionid mussels in different parts of the lake seems to be determined both by their exposure to physical forces and by sediments. 7. The local distribution of E. complanata is determined, directly and indirectly, by wind‐driven forces. These processes are likely to be important for other benthic organisms affected by similar habitat conditions (e.g. sediment characteristics, physical disturbance).  相似文献   

7.
Summary Studies of predation by roach (Rutilus rutilus) on zebra mussel (Dreissena polymorpha) in a large, eutrophic lake showed that there was a clearly marked size threshold ( 160 mm SL) above which roach began to feed on mussels. Roach preying on various sizes of mussels selected them in proportions different from their abundance and accessibility in the habitat. The mean size of mussels ingested by roach of 220 mm and larger, which fed predominantly on Dreissena, closely followed the pattern expected for a constant ratio of mean prey size to mean predator mouth size = 0.59. To explain the size selection we applied an optimal foraging approach, based on the ability of different-sized fish to crush (cost) mussels of different sizes, and hence crushing resistance, and energy contents (benefit). We found that fish smaller than 160 mm, which showed no inclination to eat Dreissena, would only be able to take small mussels with a very high cost/benefit ratio. The real switch to Dreissena would be expected in fish of 230–240 mm that could take most of their prey from highly profitable, numerous, and easily accessible size classes while keeping the mean prey size at the optimal level relative to mean predator mouth size.  相似文献   

8.
1. We used long‐term data and a simulation model to investigate temporal fluctuations in zebra mussel populations, which govern the ecological and economic impacts of this pest species. 2. The size of the zebra mussel (Dreissena polymorpha) population in the Hudson River estuary fluctuated approximately 11‐fold across a 13‐year period, following a cycle with a 2–4 year period. 3. This cycling was caused by low recruitment during years of high adult population size, rapid somatic growth of settled animals, and adult survivorship of 50% per year. 4. Adult growth and body condition were weakly correlated with phytoplankton biomass. 5. The habitat distribution of the Hudson's population changed over the 13‐year period, with an increasing proportion of the population spreading onto soft sediments over time. The character of soft‐sediment habitats in the Hudson changed because of large amounts (mean = 34 g DM m?2) of empty zebra mussel shells now in the sediments. 6. Simulation models show that zebra mussel populations can show a range of long‐term trajectories, depending on the balance between adult space limitation, larval food limitation, and disturbance. 7. Effective understanding and management of the effects of zebra mussels and other alien species depend on understanding of their long‐term demography, which may vary across ecosystems.  相似文献   

9.
1. Invasive dreissenid mussels are known to cause large ecosystem changes because of their high filter‐feeding capacity, while native bioturbators may interfere with the mussels filter feeding. In this experiment, we investigated indirect environmental interactions between invasive filter‐feeding dreissenid mussels (zebra and quagga mussels) and native recolonizing bioturbating hexagenid mayflies (Hexagenia) at two mussel densities and two Hexagenia densities in a 2‐month long laboratory experiment. 2. Mean turbidity increased with increasing density of Hexagenia and decreased with increasing density of mussels. Turbidity showed the fastest decline at the highest mussel density, and no decline or a lower rate of decline at the low mussel density, dependent on Hexagenia density. 3. Mussel growth decreased with increasing Hexagenia density at low but not at high mussel density. Moreover, growth of mussels decreased as a function of increased mean turbidity at low mussel density but not at high mussel density. Filtering activity at the highest mussel density increased after introduction of food at the lower two densities of Hexagenia, but was constantly high at the highest Hexagenia density. 4. There was no difference in emergence of Hexagenia among the treatments, but mortality of Hexagenia was higher in the presence of mussels than in their absence. 5. Our results indicate that interactions between dreissenids and hexagenids are mediated through the sediment, and depend on density of both dreissenids and hexagenids. As the natural densities of these animals vary considerably within lakes, their growth and survival because of indirect environmental interactions is expected to vary spatially.  相似文献   

10.
Beekey MA  McCabe DJ  Marsden JE 《Oecologia》2004,141(1):164-170
The introduction of zebra mussels (Dreissena spp.) to North America has resulted in dramatic changes to the complexity of benthic habitats. Changes in habitat complexity may have profound effects on predator-prey interactions in aquatic communities. Increased habitat complexity may affect prey and predator dynamics by reducing encounter rates and foraging success. Zebra mussels form thick contiguous colonies on both hard and soft substrates. While the colonization of substrata by zebra mussels has generally resulted in an increase in both the abundance and diversity of benthic invertebrate communities, it is not well known how these changes affect the foraging efficiencies of predators that prey on benthic invertebrates. We examined the effect of zebra mussels on the foraging success of four benthic predators with diverse prey-detection modalities that commonly forage in soft substrates: slimy sculpin (Cottus cognatus), brown bullhead (Ameirus nebulosus), log perch (Percina caprodes), and crayfish (Orconectes propinquus). We conducted laboratory experiments to assess the impact of zebra mussels on the foraging success of predators using a variety of prey species. We also examined habitat use by each predator over different time periods. Zebra mussel colonization of soft sediments significantly reduced the foraging efficiencies of all predators. However, the effect was dependent upon prey type. All four predators spent more time in zebra mussel habitat than in either gravel or bare sand. The overall effect of zebra mussels on benthic-feeding fishes is likely to involve a trade-off between the advantages of increased density of some prey types balanced against the reduction in foraging success resulting from potential refugia offered in the complex habitat created by zebra mussels.  相似文献   

11.
12.
1. Zebra mussels and their relatives (Dreissena spp.) have been well studied in eastern, central and western Europe as well as in North America, because of their invasiveness and economic importance. Much less is known about the biology and biogeography of indigenous (endemic) taxa of Dreissena, in the Balkans. A better knowledge of these taxa could help us (i) understand the factors triggering invasiveness in some taxa and (ii) identify other potentially invasive species. 2. Using a phylogenetic approach (2108 base pairs from three gene fragments), Dreissena spp. from natural lakes in the Balkans were studied to test whether invasive Dreissena populations occur in such lakes on the Balkan Peninsula, whether Dreissena stankovici really is endemic to the ancient Lakes Ohrid and Prespa, and to infer the phylogenetic and biogeographical relationships of Balkan dreissenids. 3. No invasive species of Dreissena, such as Dreissena polymorpha, were recorded. The supposedly ‘endemic’D. stankovici is not restricted to the ancient Lakes Ohrid and Prespa, but is the most widespread and dominant species in the west‐central Balkans. Its southern sister taxon, Dreissena blanci, occurs sympatrically with D. stankovici in Lakes Prespa, Mikri Prespa and Pamvotis. Both species are classified into the subgenus Dreissena (Carinodreissena) of which the subgenus Dreissena (Dreissena) (which includes the invasive D. polymorpha) is the sister taxon. Dreissena blanci and D. stankovici are considered to represent distinct species. 4. On a global scale, the two Balkan species have small ranges. An early Pliocene time frame for the divergence of the subgenera Carinodreissena and Dreissena is discussed, as well as potential colonization routes of the most recent common ancestor of Carinodreissena spp. 5. The ambiguous taxonomy of dreissenids in the Balkans is addressed. As nominal D. blanci presbensis from Lake Prespa has nomenclatural priority over D. stankovici, the correct name for the latter taxon should be Dreissena presbensis.  相似文献   

13.
  • 1 Zebra mussels (Dreissena polymorpha) are successful colonisers of lake littoral habitats and they interact strongly with littoral benthos. Previous research suggests that localised areas colonised by zebra mussels may be hotspots of nitrogen (N) cycling.
  • 2 The effects of zebra mussels on nitrification and denitrification rates were examined approximately every other month for 1 year in Gull Lake, Michigan, U.S.A. Littoral sediment was collected from an area free of zebra mussels and distributed into shallow trays; rocks colonised with zebra mussels were placed in half of the trays, while uncolonised rocks were placed in the remaining trays. After an incubation period of 6–8 weeks in the lake, sediment and zebra mussels were collected from the trays, replaced with new sediment and zebra mussels, and placed in the lake for the next interval. In the laboratory, sediment nitrification and denitrification rates were measured for each tray.
  • 3 Sediment nitrification rates did not increase in the presence of zebra mussels; instead nitrification rates were sensitive to changes in water temperature and increased with increasing exchangeable sediment ammonium. In contrast, denitrification rates increased in sediment trays with zebra mussels in the winter when nitrate (NO3) availability was high and when Chara did not grow in the trays.
  • 4 Sediment denitrification was NO3‐limited in all seasons, regardless of zebra mussel treatment. However, sediment in the presence of zebra mussels responded less to NO3 addition, suggesting that NO3 limitation of denitrification can be reduced by zebra mussel activity. Zebra mussels have a seasonally variable impact on sediment denitrification rates, and this may translate into altered seasonal patterns of N cycling in localised areas of lakes where they are particularly abundant.
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14.
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   

15.
A Ponto-Caspian amphipod Dikerogammarus haemobaphes has recently invaded European waters. In the recipient area, it encountered Dreissena polymorpha , a habitat-forming bivalve, co-occurring with the gammarids in their native range. We assumed that interspecific interactions between these two species, which could develop during their long-term co-evolution, may affect the gammarid behaviour in novel areas. We examined the gammarid ability to select a habitat containing living mussels and searched for cues used in that selection. We hypothesized that they may respond to such traits of a living mussel as byssal threads, activity (e.g. valve movements, filtration) and/or shell surface properties. We conducted the pairwise habitat-choice experiments in which we offered various objects to single gammarids in the following combinations: (1) living mussels versus empty shells (the general effect of living Dreissena ); (2) living mussels versus shells with added byssal threads and shells with byssus versus shells without it (the effect of byssus); (3) living mussels versus shells, both coated with nail varnish to neutralize the shell surface (the effect of mussel activity); (4) varnished versus clean living mussels (the effect of shell surface); (5) varnished versus clean stones (the effect of varnish). We checked the gammarid positions in the experimental tanks after 24 h. The gammarids preferred clean living mussels over clean shells, regardless of the presence of byssal threads under the latter. They responded to the shell surface, exhibiting preferences for clean mussels over varnished individuals. They were neither affected by the presence of byssus nor by mussel activity. The ability to detect and actively select zebra mussel habitats may be beneficial for D. haemobaphes and help it establish stable populations in newly invaded areas.  相似文献   

16.
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   

17.
Habitat engineering role of the invasive zebra mussel Dreissena polymorpha (Pallas) was studied in the Curonian lagoon, a shallow water body in the SE Baltic. Impacts of live zebra mussel clumps and its shell deposits on benthic biodiversity were differentiated and referred to unmodified (bare) sediments. Zebra mussel bed was distinguished from other habitat types by higher benthic invertebrate biomass, abundance, and species richness. The impact of live mussels on biodiversity was more pronounced than the effect of shell deposits. The structure of macrofaunal community in the habitats with >103 g/m2 of shell deposits devoid of live mussels was similar to that found within the zebra mussel bed. There was a continuous shift in species composition and abundance along the gradient ‘bare sediments—shell deposits—zebra mussel bed’. The engineering impact of zebra mussel on the benthic community became apparent both in individual patches and landscape-level analyses.  相似文献   

18.
1.  Invasive zebra ( Dreissena polymorpha ) and quagga mussels ( Dreissena bugensis ) have become widespread throughout the Great Lakes basin. However, some types of Great Lakes coastal wetlands may be unsuitable for Dreissena invasion.
2.  To test this observation, artificial substrata were placed in wetlands (with emergent vegetation) and in adjacent open water (without emergent vegetation) habitats in two types of Great Lakes coastal ecosystems: drowned river mouth (DRM) and coastal fringing systems. Wetlands in DRM systems generally have deep organic sediment and limited water movement, whereas coastal fringing wetlands generally have low to moderate amounts of organic sediment and intense wind and wave action.
3.  We did not find a significant difference in Dreissena colonisation between wetlands and adjacent open water habitat in fringing systems. However, Dreissena colonisation was significantly lower in DRM wetlands than in the adjacent open water. We also found significantly lower survival in DRM wetlands than adjacent open water habitats, whereas survival did not differ significantly in coastal fringing wetlands and the adjacent open water.
4.  Our results suggest that vulnerability to Dreissena invasion varied among wetland types with DRM wetlands being less suitable than fringing wetlands. We suggest that colonisation and survival of Dreissena is lower in wetlands with deep organic sediment and less turbulent water.  相似文献   

19.
The zebra mussel (Dreissena polymorpha) and the quagga mussel (Dreissena rostriformis bugensis) are considered as the most competitive invaders in freshwaters of Europe and North America. Although shell characteristics exist to differentiate both species, phenotypic plasticity in the genus Dreissena does not always allow a clear identification. Therefore, the need to find an accurate identification method is essential. DNA barcoding has been proven to be an adequate procedure to discriminate species. The cytochrome c oxidase subunit I mitochondrial gene (COI) is considered as the standard barcode for animals. We tested the use of this gene as an efficient DNA barcode and found that it allow rapid and accurate identification of adult Dreissena individuals.  相似文献   

20.
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