The byssal adhesion mechanism of the biofouling species Dreissena polymorpha was investigated using a combination of studies on synthetic peptide mimics of tandem repeat sequences from byssal component Dreissena polymorpha foot protein 1 (Dpfp-1) and characterization of the regions of the byssus. A 20-residue fusion peptide incorporating two Dpfp-1 repeat sequences adopts a random coil and β-turn conformation in solution, and spontaneously forms a film at the solid-liquid interface in the presence of iron (III) cations. Infrared characterization of the byssus Amide I region showed that β-sheets dominate its secondary structure, although the proportion of different secondary structures varies between regions. Matrix-assisted laser desorption ionization (MALDI) mass spectrometry of intact byssal regions identified previously unknown differences in the composition of byssal threads, plaques, and the adhesive interface, which are believed to correlate to the different roles of these components in the overall structure.

The byssal adhesion mechanism of the biofouling species Dreissena polymorpha was investigated using a combination of studies on synthetic peptide mimics of tandem repeat sequences from byssal component Dreissena polymorpha foot protein 1 (Dpfp-1) and characterization of the regions of the byssus. A 20-residue fusion peptide incorporating two Dpfp-1 repeat sequences adopts a random coil and β-turn conformation in solution, and spontaneously forms a film at the solid-liquid interface in the presence of iron (III) cations. Infrared characterization of the byssus Amide I region showed that β-sheets dominate its secondary structure, although the proportion of different secondary structures varies between regions. Matrix-assisted laser desorption ionization (MALDI) mass spectrometry of intact byssal regions identified previously unknown differences in the composition of byssal threads, plaques, and the adhesive interface, which are believed to correlate to the different roles of these components in the overall structure.

The work is focused on the status and role of zebra mussels (Dreissena polymorpha) in the water reservoir Želivka. Literature review summarizes the basic characteristics of living zebra mussels and its impact on the aquatic ecosystem. Current knowledge about this invasive bivalves show that its presence in the water reservoir has certain advantages, but also disadvantages. The main advantage is that zebra as filtrator, increases the transparency of the water and provides food for the animals living in the aquatic environment, or in its vicinity. Disadvantages are then mainly from the economic point of view, the zebra clogs pipes and thus prevents water flow and attached to marker buoys, fishing nets and attaches to the hulls of ships that can be attacked from the inside. In field part population of zebra mussels was sampled in different parts of the reservoir and identified following parameters (temperature and oxygen stratification, coverage to substrate coverage depending on the depth and the substrate, the length of shells according to the horizontal and vertical gradient filtering capacity and the volume rate). The results showed that the incidence and size of shells affects both horizontal and vertical gradient. Zebra mussels occur most depth 1-9 m on rocky, or stony substrate. The greatest incidence was found at Budeč and at Hráz, where the water is less eutrophic than the Zahrádka. Based on these parameters, and literature data was calculated hypothetical filter capacity and discussed its possible impact on the ecosystem components of the reservoir.

No description available.

No description available.

The Summer (May through August) community of crustacean zooplankton and zebra mussel (Dreissena polvmorpha) larvae at a 15 m sample site in Lake Michigan near Michigan City was evaluated for the years 1990 through 1994. Yearly mean densities were compared with investigations done at the same sample location by Johnson (1972) and Ball State University (unpublished data) during 1970 and 1971, respectively to investigate possible changes in community composition during the past 25 years. Potential declines in crustacean zooplankton relating to the 1991 introduction of the filter-feeding zebra mussel were also evaluated.Overall declines in major species since 1970-71 included Bosmina longirostris, Daphnia retrocurva, and Diacyclops thomasi. Recent increases in the nearshore fish population of alewife (Alosa pseudoharengus) and spottail shiner (Notropis hudsonius) may have influenced the densities of these species in recent years. Copepod nauplii were the only crustaceans to increase in overall abundance since the period of 1970-71, as the number of invertebrate predators appeared to decrease. Other species did not show any noticeable change in long-term abundance or during the 1990-94 period.Zebra mussel larvae were first observed in the zooplankton complex studied on June 17, 1991. -Densities of larvae reached maximal levels for the period of study in 1994 with two large reproductive pulses of 195,000 and 210,000/m3 in June and August, respectively. The mean abundance during 1994 made up 65% of the total crustacean zooplankton/zebra mussel community complex. Evaluation of the vertical stratification of zebra mussel larvae in 1994 revealed a strong (r2=0.75, p<0.0005) tendency for veligers to remain in the upper 10 m of the water column due to thermal stratification. / Department of Biology

Biological invasions are among the leading causes of species diversity loss; however, the impacts of invasion are context-dependent and can vary with the local environment. The mechanisms governing variation in impact and their relationship to specific abiotic and biotic factors remain largely unexplored. Recent local declines in native unionid mussels have been attributed to the invasion of North American lakes and rivers by the Eurasian zebra mussel ( Dreissena polymorpha), as a result of intense fouling of unionid shells by zebra mussels. My research investigated the role of abiotic and biotic factors in mediating the impact of zebra mussels on native mussels. I examined the impact of zebra mussels on unionids in a habitat thought to be suboptimal for zebra mussels and compared this to the impact observed in other invaded habitats. A predictive model relating fouling intensity to local environmental variables (calcium concentration, sediment particle size) was developed, and a predator-exclusion experiment was conducted to investigate the role of predation in mediating fouling intensity. Overall, I found that two abiotic factors of the local environment were significant predictors of fouling intensity and that relationships used to predict the impact of zebra mussels could be extended to a broader range of habitats.

No description available.

Zebra mussels (Dreissena polymorpha) have invaded a great proportion of the waters of the eastern part of North America. This mollusk may be a useful sentinel species for bioaccumulation of heavy metals and organic contaminants in aquatic ecosystems. The zebra mussel's capacity to bioaccumulate cadmium at environmentally relevant exposure and to sequester metals in metal-binding proteins, metallothioneins, was investigated. Elevated (relative to control) concentrations of Cd$ sp{2+}$ were detected in Dreissena exposed to $ ge$2 $ mu$g Cd/liter suggesting that zebra mussels cannot regulate Cd$ sp{2+}$ of trace exposure concentration. More than 85% of the measured Cd$ sp{2+}$ was bound to metallothioneins. / Lesser scaup (Aythya affinis) was assessed as a model species for potential impacts of zebra mussels on higher trophic levels. The feasibility of incubating and rearing scaup in semi-natural conditions was evaluated. A series of biomarkers was assessed in 3 groups of scaup fed a contaminant-free diet or diets containing zebra mussels from the St-Lawrence River or Lake Erie. / Lesser scaup proved to be a suitable species to raise in captivity providing daily water misting through out incubation and strict hygiene conditions during brooding. A hatching success of 89% was achieved. Appropriate housing, feeding and bathing conditions yielded low (3%) post-hatching mortality. / Phagocytosis and respiratory burst activities of heterophils of scaup were suppressed after 6 weeks of feeding on zebra mussels, compared to the control group. These two heterophilic functions were negatively correlated with the incidence of pododermatitis (bacterial feet infection), suggesting a suppression of the non specific immunity. Increased liver/body mass ratio and decreased hepatic vitamin A (retinol and retinyl palmitate) concentrations were observed in scaups fed zebra mussels. Lipid accumulation and glycogen overload were found in the livers of scaups fed mussels from the St-Lawrence River and the Lake Erie groups, respectively. These immunological, biochemical and histopathological biomarkers show promise for monitoring "early" injury and may help in the understanding of health impairment of different species of waterfowl exposed to xenobiotics via contaminated food sources.

Toxic antifouling agents such as tributyltin (TBT) and triphenyltin (TPT) have been released in aquatic ecosystems through the use of antifouling paint applied to ship hulls, pleasure crafts and fish nets. The purpose of this study was to assess the use of zebra mussels (Dreissena polymorpha ) as a biomonitor for investigating the geographical variations of organotin bioavailability along the St. Lawrence River. Organotins TBT and TPT and their degradation products were first measured in the soft tissues of zebra mussels collected from along the River. High concentrations of TBT were found in mussels from Bassin Louise, a marina in Quebec City (1442 ng/g wet weight). TPT concentrations were elevated at 2 sites near Quebec City (252 and 530 ng/g wet weight). A follow-up study assessed the extent of the distribution of organotins from the contaminated marina to the River system by measuring organotin concentrations in zebra mussels and in sediments collected River near Quebec City. The highest concentration of TBT was found in Bassin Louise (1078 ng/g wet weight) and elevated concentrations were found in two other marinas. The concentrations decreased sharply to background levels just outside the marinas. All butyltins were detected in all sediments analysed. There was a significant correlation between TBT in sediments and mussels. These studies suggest that organotin contamination may remain a problem in localized freshwaters in the St. Lawrence River.