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Widespread hybridisation between roach (Rutilus rutilus L.) and common bream (Abramis brama L.) was recorded throughout Ireland in the 1970s and 1980s following the establishment of invasive roach populations. To identify the post-invasion levels of hybridisation, a fish stock monitoring program was implemented in lake and river sites, predominantly within the extended River Shannon catchment. Roach x bream hybrids were the second or third most prolific fish recorded during these surveys, accounting for approximately 20%-30% of fish caught. The abundance of roach x bream hybrids is unique to Ireland and represents a potential threat to bream populations in invaded catchments. [ABSTRACT FROM AUTHOR]

Atmospheric deposition was measured at three sites in the Pensacola Bay watershed, Florida, between November 2004 and December 2007. Mercury deposition in the Pensacola Bay watershed was similar to that from nearby Mercury Deposition Network sites along the Northern Gulf of Mexico coast. Mercury deposition during the summer months is higher than other months due to higher concentrations in rainfall throughout the region. Deposition of constituents like H+, sulfate, nitrate, ammonium, chloride and sodium, were much higher in Pensacola Bay that at National Atmospheric Deposition Program (NADP) sites. Chloride and sodium fluxes are higher because Pensacola Bay sites are closer to the Gulf of Mexico which is a source of sea salt aerosols. Acid rain constituents, H+, sulfate, nitrate and ammonium are most likely higher at Pensacola Bay sites because these sites are much closer to emission sources of these constituents than NADP sites, particularly two Florida NADP sites, FL14 and FL23, which are located in rural counties far from major industrial activities. [ABSTRACT FROM AUTHOR]

The growth rates of bream, Abramis brama (L.), were determined in three Irish Canals: the Royal and Grand Canals, and the Barrow Line. Compared with growth patterns for other Irish and European waters, the growth of bream was fast in the Royal Canal, but slow to moderate for the Grand Canal and the Barrow Line. Significant differences in bream growth in terms of both length and weight were found between the three canal systems, and between canal levels, particularly in the Grand Canal. Associations between growth, and (1) alkalinity, (2) total fish biomass and (3) the ratio of bream biomass to total fish biomass were also found. However, it was considered that these three factors alone were not sufficient to explain the differences in growth. Productivity was implicated as the main factor controlling bream growth because fish species diversity was greater and total fish biomass was generally higher in levels of the Grand Canal with faster growing bream populations. The division between ‘fast’ and ‘slow’ growing bream also corresponded with a change in the aquatic weed community. There is evidence to suggest that there was a corresponding change in macro-invertebrate community structure and density. Angler usage as another factor in promoting growth is discussed. The implications for the future management and development of these canals are outlined. [ABSTRACT FROM AUTHOR]

In January 1989 a major breach in an embanked section of the Grand Canal occurred. As a result, a 2.5-km long section required complete reconstruction. This work was completed in approximately 12 months, ata cost of IR 1.5 million. The canal was rewatered in March 1990. Thebanksides, above normal water level, were dressed with a layer of moss peat and seeded with a mixture of grasses. The grass roots failed to bind the peat to the sub-layer of Puddle Clay and significant erosion resulted in the season of treatment. In order to halt the harmfulerosion and to expedite the natural reed colonisation process, rootsand rhizomes from established monocotyledonous plant colonies, external to the canal, were acquired. This paper presents the findings from transplantation trials using Schoenoplectus lacustris, Glyceria maxima and Phragmites australis from river and lake habitats and comments on the efficiency and cost-effectiveness of this operation. The value of reeds in amenity watercourses is discussed. [ABSTRACT FROM AUTHOR]