Arctic charr in Britain and Ireland – 15 species or one?

Abstract –  From both a modern and a historical perspective there is little doubt that the Arctic charr, Salvelinus alpinus , in Britain and Ireland (as well as elsewhere) is a 'difficult' species. Historically 15 separate species have been recognised from populations in Britain and Ireland and there have been recent attempts to reassert these specific names. Here we review the evidence for the status of these 'species'. We conclude that the evidence for these 15 being afforded full species status is poor. However, both historical and contemporary data show that Salvelinus alpinus (Linnaeus 1758) in Britain and Ireland exhibits levels of variability in form that is much greater than in other species. We argue that a comprehensive genotypic and phenotypic survey of charr populations in Britain and Ireland is required to determine the full extent of variability and the status of populations with a view of providing suitable protection.     

The status of Arctic charr Salvelinus alpinus in Britain and Ireland

Abstract –  The Arctic charr occurs in lakes across Britain and Ireland and was previously described here as 15 separate species. Most authorities now agree that all these stocks belong to a single polymorphic species complex Salvelinus alpinus (L.). This fish is given little protection in British and Irish law and there has been a steady loss of natural populations in recent years in all the countries concerned. A few new stocks have been created either intentionally or accidentally. In Scotland, only a small proportion of the 258 recorded natural populations has been studied and at least 12 of these are now extinct. There are at least four introduced populations originating from native Scottish stocks, but the fate of stocks introduced from Canada for aquaculture is uncertain. In England, there are eight extant populations in Cumbria and four others extinct. The status of introduced stocks in England is uncertain but there is probably one population surviving in Yorkshire. In Wales, eight lakes with resident Arctic charr populations have been recorded, three of these populations are natural, one is extinct and four have been introduced. In Ireland, of the 74 known populations, approximately 30% are extinct. There is no evidence to indicate that introduced stocks (some of them from Iceland) in a small number of lakes have survived there. A range of factors is involved in the extinction of populations and these include pollution, eutrophication, acidification, afforestation, engineering, exploitation, aquaculture, introductions and climate change. Much research remains to be done and unique stocks of this valuable species will continue to be lost unless positive action is taken through local conservation management backed by appropriate national legislation.     

Conservation of freshwater fish in the British Isles: The current status and biology of threatened species

1. The objective of this paper is to review the status of all freshwater fishes in the British Isles and to identify theatened species, races and communities which are in need of conservation. 2. Using objective criteria to assess the degree of threat, two of the 55 freshwater species known in the British Isles are thought to be extinct here and eight are believed to be under significant threat. 3. The biology of these ten species is reviewed. They are: Sturgeon Acipenser sturio, Allis Shad Alosa alosa, Twaite Shad Alosa fallax, Arctic Charr Salvelinus alpinus, Houting Coregonus oxyrinchus (extinct), Powan Coregonus lavaretus, Pollan Coregonus autumnalis, Vendace Coregonus albula, Smelt Osmerus eperlanus and Burbot Lota lota (extinct). 4. In addition, there are several races of commoner species which are believed to be worthy of special conservation measures. These fish include the purely freshwater race of River Lamprey Lampetra fluviatilis in Loch Lomond, dwarf Brook Lampreys Lampetra planeri in the Inner Hebrides, spineless Three-spined Sticklebacks Gasterosteus aculeatus in the Outer Hebrides and a number of important races of Brown Trout Salmo trutta in various waters in Ireland and Scotland. 5. There is also a range of fish communities in individual rivers and lakes which merit conservation attention. These are important for a variety of reasons, including high (and very low) diversity, unique assemblages, pristine stocks and highly characteristic communities. 6. The major threats to these species and communities include industrial and domestic pollution, acidification, land use changes, river barriers, drainage, fish farming, fishery management and the introduction of new species. 7. The identification of these threatened fishes and important freshwater sites provides a foundation for a review of existing protection in the British Isles and a major fish conservation management programme. These will be described in subsequent papers.     

Allelic losses and gains during translocations of a high conservation value fish,Coregonus lavaretus

1. The use of translocations to establish new or ‘refuge’ populations for species with high conservation value is controversial but widely used in conservation management. One of the risks of this approach is that an establishing population does not adequately capture the genetic diversity of the donor gene pool. This effect, rarely examined, is tested here.
2. In this study the genetic consequences of two conservation translocations after five generations (16 years) of the European whitefish, Coregonus lavaretus, were quantified. Both translocations were made using almost the same genetic groups and thus represent a partly replicated natural study.
3. Analysis of 12 informative microsatellites showed that expected heterozygosity, the mean number of alleles per locus and allelic richness did not differ between donor and translocated populations. There was also no loss of heterozygosity in the translocated populations, nor deviations from Hardy–Weinberg equilibrium expectations, nor signs of linkage disequilibrium.
4. All populations were genetically differentiated but pairwise F_ST values were low, indicating that the magnitude of divergence was small.
5. There was no evidence of inbreeding but there were significant differences in private allelic richness between donor and translocated populations. Of 50 alleles found in the donor population, 16% of the rarer alleles were lost in one translocated population and 8% in the other.
6. Allele loss without a reduction in heterozygosity strongly points to stochastic drift effects having occurred following translocation. The evidence indicates that alleles that were not detected in the donor population have arisen de novo in the translocated populations.
7. It is concluded that conservation translocations comprising even a modest number of propagules can successfully capture a high proportion of genetic variation of the host population, and that reduced genetic variation in the translocated population may be mitigated by the emergence of new variation over short time periods.

     

Analysis of Amblyomma surveillance data in the Caribbean: Lessons for future control programmes

Amblyomma variegatum, the Tropical Bont Tick (TBT), is the principal vector of heartwater and is associated with dermatophilosis, major causes of losses in animal production and mortality in Caribbean livestock. From 1995 to 2007, the Caribbean Amblyomma Programme (CAP) supported treatment and surveillance activities in 11 islands of the Eastern Caribbean with an initial objective of eradicating TBT. In addition to control activities, surveillance data were collected between 1997 and 2006 in a unique regional database. We report the analysis of the surveillance data from four islands (Nevis, St Kitts, St Lucia, and Barbados) where control and surveillance followed the initial protocol and where enough data were collected. We describe the evolution of TBT infestation levels and the efforts carried out throughout the surveillance period. Logistic regression identified factors associated with herds found infested with TBT. Overall, treatment programmes were associated with a decrease in proportion of TBT-infested farms. High surveillance efforts were carried out throughout the 1997–2007 period for all island of interest, but inadequate level of surveillance was observed in several quarters especially for St Kitts. Third quarter of the year, as indication of adult TBT seasonality on livestock, was significantly associated with the risk of detecting TBT in Nevis and St Kitts livestock farms. Also, presence of cattle in Nevis farms was shown associated with an increasing probability of farms being declared TBT-infested. Outcomes of these analyses provide basis for recommendations to improve future national and regional control and surveillance activities. This analysis demonstrates the usefulness of long term and adequate surveillance data for control programmes and identification of factors associated with risk of having infested herds.     

The conservation of freshwater fishes in the British isles

This paper briefly reviews the status and distribution of populations of freshwater fishes in the British Isles and their worth as a resource. The total value of freshwater fishes to the community is far greater than is normally appreciated and includes, in addition to the economic sport and commercial fisheries, amenity, recreational, educational, and scientific, aspects as well as a potentially useful store of genetic material for the future. The main human pressures on existing fish stocks are discussed under the headings of fisheries, pollution, and land-used. The principal trends in the British Isles are away from natural and stable mixed fish populations towards artificially maintained, unstable stocks of a few species of sporting or commercial value. In particular the rarer, more sensitive, fish stocks with poor powers of distribution are being eradicated and replaced by commoner, more robust forms with greater powers of distribution. The rarer species and genetic strains can only survive if constructive conservation projects are initiated expeditiously at a variety of levels.     

Local Control of Microdomain Orientation in Diblock Copolymer Thin Films with Electric Fields

Local control of the domain orientation in diblock copolymer thin films can be obtained by the application of electric fields on micrometer-length scales. Thin films of an asymmetric polystyrene-polymethylmethacrylate diblock copolymer, with cylindrical polymethylmethacrylate microdomains, were spin-coated onto substrates previously patterned with planar electrodes. The substrates, 100-nanometer-thick silicon nitride membranes, allow direct observation of the electrodes and the copolymer domain structure by transmission electron microscopy. The cylinders aligned parallel to the electric field lines for fields exceeding 30 kilovolts per centimeter, after annealing at 250°C in an inert atmosphere for 24 hours. This technique could find application in nanostructure fabrication.