• Impact of naturally spawning captive-bred Atlantic salmon on wild populations: depressed recruitment and increased risk of climate-mediated extinction

      McGinnity, P; Jennings, E; deEyto, E; Allott, N; Samuelsson, P; Rogan, G; Whelan, K; Cross, T (Royal Society Publishing, 2009)
      The assessment report of the 4th International Panel on Climate Change confirms that global warming is strongly affecting biological systems and that 20–30% of species risk extinction from projected future increases in temperature. It is essential that any measures taken to conserve individual species and their constituent populations against climate-mediated declines are appropriate. The release of captive bred animals to augment wild populations is a widespread management strategy for many species but has proven controversial. Using a regression model based on a 37-year study of wild and sea ranched Atlantic salmon (Salmo salar) spawning together in the wild, we show that the escape of captive bred animals into the wild can substantially depress recruitment and more specifically disrupt the capacity of natural populations to adapt to higher winter water temperatures associated with climate variability. We speculate the mechanisms underlying this seasonal response and suggest that an explanation based on bio-energetic processes with physiological responses synchronized by photoperiod is plausible. Furthermore, we predict, by running the model forward using projected future climate scenarios, that these cultured fish substantially increase the risk of extinction for the studied population within 20 generations. In contrast, we show that positive outcomes to climate change are possible if captive bred animals are prevented from breeding in the wild. Rather than imposing an additional genetic load on wild populations by releasing maladapted captive bred animals, we propose that conservation efforts should focus on optimizing conditions for adaptation to occur by reducing exploitation and protecting critical habitats. Our findings are likely to hold true for most poikilothermic species where captive breeding programmes are used in population management.
    • Improved Isolation Procedure for Azaspiracids from Shellfish, Structural Elucidation of Azaspiracid-6 and Stability studies

      Kilcoyne, Jane; Keogh, Adela; Clancy, Ger; Le Blanc, Pat; Burton, Ian; Quilliam, Michael A.; Hess, Philipp; Miles, Christopher O. (ACS Publications, 2012)
      Azaspiracids are a group of lipophilic polyether toxins produced by the small dinoflagellate Azadinium spinosum. They may accumulate in shellfish and can result in illnesses when consumed by humans. Research into analytical methods, chemistry, metabolism, and toxicology of azaspiracids has been severely constrained by the scarcity of high-purity azaspiracids. Consequently, since their discovery in 1995, considerable efforts have been made to develop methods for the isolation of azaspiracids in sufficient amounts and purities for toxicological studies, in addition to the preparation of standard reference materials. A seven-step procedure was improved for the isolation of azaspiracids-1–3 (1, 2, and 3) increasing recoveries 2-fold as compared to previous methods and leading to isolation of sufficiently purified azaspiracid-6 (6) for structural determination by NMR spectroscopy. The procedure, which involved a series of partitioning and column chromatography steps, was performed on 500 g of Mytilus edulis hepatopancreas tissue containing 14 mg of 1. Overall yields of 1 (52%), 2 (43%), 3 (43%), and 6 (38%) were good, and purities were confirmed by NMR spectroscopy. The structure of 6 was determined by one- and two-dimensional NMR spectroscopy and mass spectrometry. The stability of 6 relative to 1 was also assessed in three solvents in a short-term study that demonstrated the greatest stability in aqueous acetonitrile.
    • Inclusion of ecological, economic, social, and institutional considerations when setting targets and limits for multispecies fisheries

      Rindorf, Anna; Dichmont, Catherine M.; Thorson, James; Charles, Anthony; Clausen, Lotte Worsøe; Degnbol, Poul; Garcia, Dorleta; Hintzen, Niels T.; Kempf, Alexander; Levin, Phillip; et al. (Oxford University Press (OUP), 2017)
      Targets and limits for long-term management are used in fisheries advice to operationalize the way management reflects societal priorities on ecological, economic, social and institutional aspects. This study reflects on the available published literature as well as new research presented at the international ICES/Myfish symposium on targets and limits for long term fisheries management. We examine the inclusion of ecological, economic, social and institutional objectives in fisheries management, with the aim of progressing towards including all four objectives when setting management targets or limits, or both, for multispecies fisheries. The topics covered include ecological, economic, social and governance objectives in fisheries management, consistent approaches to management, uncertainty and variability, and fisheries governance. We end by identifying ten ways to more effectively include multiple objectives in setting targets and limits in ecosystem based fisheries management.
    • Inferring marine distribution of Canadian and Irish Atlantic salmon (Salmo salar L.) in the North Atlantic from tissue concentrations of bio-accumulated Caesium 137

      Spares, Aaron D.; Reader, Jeffery M.; Stokesbury, Michael J.W.; McDermott, Tom; Zikovsky, Lubomir; Dadswell, Michael J. (Oxford University Press, 2007)
      Atlantic salmon returning from marine migrations to eastern Canada and western Ireland during 2002 and 2003 were analysed for tissue concentrations of bio-accumulated caesium 137 (137Cs). Salmon from Canadian and Irish waters demonstrated concentrations (0.20 ± 0.14 Bq kg-1 and 0.19 ± 0.09 Bq kg-1, mean ± s.d., respectively) suggesting similar oceanic feeding distributions during migration. Canadian aquaculture escapees had a similar mean tissue concentration (0.28 ± 0.22 Bq kg-1), suggesting migration with wild salmon. However, significantly higher concentrations in 1-sea-winter (1SW) escapees (0.43 ± 0.25 Bq kg-1) may alternatively suggest feeding within local estuaries. High concentrations in some Canadian 1SW salmon indicated trans-Atlantic migration. Low concentrations of Canadian multi-sea-winter (MSW) salmon suggested a feeding distribution in the Labrador and Irminger Seas before homeward migration, because those regions have the lowest surface water 137Cs levels. Estimates of wild Canadian and Irish salmon feeding east of the Faroes (~8oW) were 14.2% and 10.0% (1SW, 24.7% and 11.5%; MSW, 2.9% and 0.0%), respectively. We propose that most anadromous North Atlantic salmon utilize the North Atlantic Gyre for marine migration and should be classified as a single trans-Atlantic straddling stock.
    • Inorganic carbon and pH levels in the Rockall Trough 1991-2010

      McGrath, Triona; Kivimäe, Caroline; Tanhua, Toste; Cave, Rachel R.; McGovern, Evin (Elsevier, 2012)
      The accumulation of anthropogenic CO2 in the oceans is altering seawater carbonate chemistry. Investigation and monitoring of the carbonate parameters is therefore necessary to understand potential impacts on ocean ecosystems. Total alkalinity (AT) and dissolved inorganic carbon (CT) were sampled across the Rockall Trough in Feb 2009 (CE0903) and Feb 2010 (CE10002) as part of a baseline study of inorganic carbon chemistry in Irish shelf waters. The results have been compared with data from WOCE surveys A01E (Sept 1991), A01 (Dec 1994), AR24 (Nov 1996) and A24 (June 1997). The 2009 and 2010 datasets provide a snapshot of the biogeochemical parameters which can act as a baseline of inorganic carbon and acidity levels in surface waters of the Rockall Trough in late winter for future comparison since previous surveys in the area have been affected by biological activity. The dataset also offers the possibility to compare decadal changes in subsurface waters. The temporal evolution of anthropogenic carbon (D Cant) between the 1990s and 2010 was evaluated using two separate methods; (i) a comparison of the concentrations of CT between surveys, after correcting it for remineralisation of organic material and formation and dissolution of calcium carbonate (D CT-abio) and (ii) an extended Multiple Linear Regression was used to calculate the D Cant (D Cant eMLR). There was an increase in D CT-abio and D Cant eMLR of 1874 umol kg1 and1974 umol kg1, respectively, in the subsurface waters between 1991 and 2010, equivalent to a decrease of 0.0407± 0.003 pH units over the 19 year period. There was an increasein both D CT-abio and D Cant eMLR of 874 umol kg1 in Labrador Sea Water (LSW) in the Trough between 1991 and 2010, and LSW has acidified by 0.0297±0.002 pH units over the same time period. A reduction in calcite and aragonite saturation states was observed, which may have implications for calcifying organisms in the region.
    • An integrated approach to the toxicity assessment of Irish marine sediments. Application of porewater Toxicity Identification Evaluation (TIE) to Irish marine sediments.

      Macken, A; Giltrap, M; Foley, B; McGovern, E; McHugh, B; Davoren, M (Elsevier, 2009)
      An integrated approach to the ecotoxicological assessment of Irish marine sediments was carried out between 2004 and 2007. Phase I Toxicity Identification Evaluation (TIE) of sediment porewaters from two sites on the east coast of Ireland were conducted. Initial Tier I screening of three Irish sites identified the need for TIE after significant toxicity was observed with Tisbe battagliai and the Microtox® assay at two of the assayed sites (Alexandra Basin and Dunmore East). Porewaters classified as toxic were characterised using four manipulations, ethylenediaminetetraacetic acid (EDTA) chelation, sodium thiosulphate addition, C18 Solid Phase Extraction (SPE) and Cation Exchange (CE) SPE. Prior to initial testing, and TIE manipulations, all porewater samples were frozen at -20 ºC for several months until required. After initial Tier I testing Alexandra Basin porewater was classified as highly toxic by both assays while Dunmore East porewater only warranted a TIE with T. battagliai. Results of TIE manipulations for Alexandra Basin porewater and the Microtox® Basic test were inconclusive. The toxicity of the porewater in this assay was significantly reduced after freezing. Three experimental episodes were conducted with one month between each for the Alexandra Basin porewater. After each month of freezing the baseline toxicity was further reduced in the Microtox® assay, therefore it was not possible to draw accurate conclusions on the nature of the active contaminants in the sample. However, toxicity to T. battalgiai did not change after storage of the porewater. The C18 and CE SPE decreased the toxicity of Alexandra Basin porewater to the copepod indicating that both organic and cationic compounds (e.g. metals) were active in the sample. Dunmore East porewater was assayed with T. battalgiai and again a combination of organic and inorganic compounds were found to be partly responsible for the observed toxicity (C18, CE SPE and EDTA reduced toxicity). Results from these TIEs provide insight into the complexity of interpreting marine TIE data from porewater studies where mixtures of unknown substances are present.
    • Integrating vessel monitoring systems (VMS) data with daily catch data from logbooks to explore the spatial distribution of catch and effort at high resolution.

      Lordan, C; Gerritsen, H.D. (Oxford University Press, 2011)
      Vessel monitoring systems (VMS) automatically collect positional data from fishing vessels. The VMS data can be linked to catch data from logbooks to provide a census of spatially resolved catch-and-effort data. We explore and validate the most appropriate and practical method for integrating Irish VMS and logbook data. A simple speed rule is applied to identify VMS records that correspond to fishing activity. These data are then integrated with the catch data from logbooks using date and vessel identifier. A number of assumptions were investigated, and the resulting distribution maps of catch and effort appear to be unbiased. The method is illustrated with an example of a time-series of spatially explicit catch-per-unit-effort (cpue) estimates. The proposed method is relatively simple and does not require specialist software or computationally intensive methods. It will be possible to generalize this approach to similar datasets that are available within the EU and many other regions. Analysis of integrated VMS and logbook data will allow fisheries data to be analysed on a considerably finer spatial scale than was possible in the past, which opens up a range of potential applications.
    • Latitude and lake size are important predictors of over-lake atmospheric stability

      Woolway, R. Iestyn; Verburg, Piet; Merchant, Christopher J.; Lenters, John D.; Hamilton, David P.; Brookes, Justin; Kelly, Sean; Hook, Simon; Laas, Alo; Pierson, Don; et al. (American Geophysical Union (AGU), 2017)
      Turbulent fluxes across the air‐water interface are integral to determining lake heat budgets, evaporation, and carbon emissions from lakes. The stability of the atmospheric boundary layer (ABL) influences the exchange of turbulent energy. We explore the differences in over‐lake ABL stability using data from 39 globally distributed lakes. The frequency of unstable ABL conditions varied between lakes from 71 to 100% of the time, with average air temperatures typically several degrees below the average lake surface temperature. This difference increased with decreasing latitude, resulting in a more frequently unstable ABL and a more efficient energy transfer to and from the atmosphere, toward the tropics. In addition, during summer the frequency of unstable ABL conditions decreased with increasing lake surface area. The dependency of ABL stability on latitude and lake size has implications for heat loss and carbon fluxes from lakes, the hydrologic cycle, and climate change effects.
    • Lessons for fisheries management from the EU cod recovery plan

      Kraak, Sarah B. M.; Bailey, Nick; Cardinale, Massimiliano; Darby, Chris; De Oliveira, José A. A.; Eero, Margit; Graham, Norman; Holmes, Steven; Jakobsen, Tore; Kempf, Alexander; et al. (Elsevier, 2012)
      The performance of the EU long-term management plan for cod stocks, in force since 2009, is analysed focusing on the human and institutional factors. The plan operates through landings quotas (TACs) and effort restrictions following a Harvest Control Rule, and deploys a novel instrument allowing Member States to ‘buy back’ or increase fishing effort for fleet segments engaged in cod-avoidance measures. The stipulated fishing mortality reductions have not been achieved. On the positive side, the ‘buy-back’ instrument has led to increased uptake of selective gear and implementation of permanent and real-time temporary closures. On the negative side, ignoring the dimension of fishers as reactive agents in the design, the impact assessment, and the annual implementation of the measures has contributed to the failure to adequately implement the plan and achieve its objectives. The main problem is that the landings quotas taken in a mixed fishery did not limit catches because fishers were incentivised to continue fishing and discard overquota catch while quota for other species was available. The effort limitations intended to reduce this effect were insufficient to adequately limit fishing mortality in targeted fisheries, although fishers experienced them as prohibiting the full uptake of other quotas. Recommendations for future plans include (i) management through catch rather than landings quotas, (ii) the internalisation of the costs of exceeding quotas, (iii) use of more selective gear types, (iv) the development of appropriate metrics as a basis for regulatory measures and for evaluations, (v) participatory governance, (vi) fishery-based management, (vii) flexibility in fishing strategy at vessel level.
    • ‘Linking Herring’: do we really understand plasticity?

      Dickey‐Collas, M; Clarke, M; Slotte, A (Oxford University Press, 2009)
      The symposium was organized to link our understanding of herring biology, population dynamics, and exploitation in the context of ecosystem complexity. It is beyond argument that herring play a pivotal role in shaping the structure and dynamics of many boreal continental-shelf ecosystems. Therefore, in moving to an ecosystem approach to fishery management, the time seemed right for ICES to hold another herring symposium. Since the last ICES symposia on herring in the 1960s (“Herring Symposium”, 1961; “Biology of Early Stages and Recruitment Mechanisms of Herring”, 1968), many of the old paradigms have been rejected, and substantial progress has been made by striking out along new avenues. In addressing this particular topic, we were also able to follow on from the decadal herring symposia series held in North America, and thus cover new research from both the ICES and PICES communities. The symposium took place from 26 to 29 August 2008, at the National University of Ireland, Galway, Ireland.
    • A Low-Complexity Mosaicing Algorithm for Stock Assessment of Seabed-Burrowing Species

      Corrigan, D.; Sooknanan, K.; Doyle, J.; Lordan, C.; Kokaram, A. (IEEE Xplore, 2018)
      This paper proposes an algorithm for mosaicing videos generated during stock assessment of seabed-burrowing species. In these surveys, video transects of the seabed are captured and the population is estimated by counting the number of burrows in the video. The mosaicing algorithm is designed to process a large amount of video data and summarize the relevant features for the survey in a single image. Hence, the algorithm is designed to be computationally inexpensive while maintaining a high degree of robustness. We adopt a registration algorithm that employs a simple translational motion model and generates a mapping to the mosaic coordinate system using a concatenation of frame-by-frame homographies. A temporal smoothness prior is used in a maximum a posteriori homography estimation algorithm to reduce noise in the motion parameters in images with small amounts of texture detail. A multiband blending scheme renders the mosaic and is optimized for the application requirements. Tests on a large data set show that the algorithm is robust enough to allow the use of mosaics as a medium for burrow counting. This will increase the verifiability of the stock assessments as well as generate a ground truth data set for the learning of an automated burrow counting algorithm.
    • Managing a complex population structure: exploring the importance of information from fisheries-independent sources

      Hintzen, N.T.; Roel, B.; Benden, D.; Clarke, M.; Egan, A.; Nash, R.D.M.; Rohlf, N.; Hatfield, E.M.C. (Oxford University Press, 2014)
      Natural resource managers aim to manage fish stocks at sustainable levels. Often, management of these stocks is based on the results of analytical stock assessments. Accurate catch data, which can be attributed to a specific population unit and reflects the population structure, are needed for these approaches. Often though, the quality of the catch data is compromised when dealing with a complex population structure where fish of different population units mix in a fishery. The herring population units west of the British Isles are prone to mixing. Here, the inability to perfectly allocate the fish caught to the population unit they originate from, due to classification problems, poses problems for management. These mixing proportions are often unknown; therefore, we use simulation modelling combined with management strategy evaluation to evaluate the role fisheries-independent surveys can play in an assessment to provide unbiased results, irrespective of population unit mixing and classification success. We show that failure to account for mixing is one of the major drivers of biased estimates of population abundance, affecting biomass reference points and MSY targets. When mixing of population units occurs, the role a survey can play to provide unbiased assessment results is limited. Either different assessment models should be employed or stock status should be considered from the survey data alone. In addition, correctly classifying the origin of fish is especially important for those population units that are markedly smaller in size than other units in the population complex. Without high classification success rates, smaller population units are extremely vulnerable to overexploitation.
    • Migration and Fisheries of North East Atlantic Mackerel (Scomber scombrus) in Autumn and Winter

      Jansen, Teunis; Campbell, Andrew; Kelly, Ciarán; Hátún, Hjálmar; Payne, Mark R. (Public Library of Science (PLOS), 2012)
      It has been suggested that observed spatial variation in mackerel fisheries, extending over several hundreds of kilometers, is reflective of climate-driven changes in mackerel migration patterns. Previous studies have been unable to clearly demonstrate this link. In this paper we demonstrate correlation between temperature and mackerel migration/distribution as proxied by mackerel catch data from both scientific bottom trawl surveys and commercial fisheries. We show that mackerel aggregate and migrate distances of up to 500 km along the continental shelf edge from mid-November to early March. The path of this migration coincides with the location of the relatively warm shelf edge current and, as a consequence of this affinity, mackerel are guided towards the main spawning area in the south. Using a simulated time series of temperature of the shelf edge current we show that variations in the timing of the migration are significantly correlated to temperature fluctuations within the current. The proposed proxies for mackerel distribution were found to be significantly correlated. However, the correlations were weak and only significant during periods without substantial legislative or technical developments. Substantial caution should therefore be exercised when using such data as proxies for mackerel distribution. Our results include a new temperature record for the shelf edge current obtained by embedding the available hydrographic observations within a statistical model needed to understand the migration through large parts of the life of adult mackerel and for the management of this major international fishery.
    • Mismatch between fish landings and market trends: a western European case study

      Miller, Dana; Clarke, Maurice; Mariani, Stefano (Elsevier, 2012)
      As an island nation, Ireland is connected to and responsible for the seas that surround it. Fishing has historically been one of the major anthropogenic activities linking Irish society to the marine environment. Deriving an approach from historical ecology, we investigated temporal patterns in the diversity of seafood landed, traded and marketed in Ireland by collating long-term datasets acquired from government sources and through conducting contemporary product surveys. Our findings suggest that consumer preferences have not adapted to changes in local resource supply. From the beginning of the 20th century, Irish landings of some of the traditionally most important seafood products have gradually grown, then sharply declined within the most recent 10-20 years, but access to ample supply appears to have been maintained in the Irish marketplace. Our results indicate that this trend has been concealed from consumers through import, aquaculture production and mislabeling. Future intentions of responsible management must incorporate policy implementation and enforcement, consumer education and industry transparency.
    • A Model Compound Study: The ecotoxicological evaluation of five organic contaminants with a battery of marine bioassays

      Macken, A; Giltrap, M; Foley, B; McGovern, E; McHugh, B; Davoren, M (Elsevier, 2008)
      This paper describes the ecotoxicological evaluation of five organic contaminants frequently detected in marine sediments (tributyltin, triphenyltin, benzo[a]pyrene, fluoranthene, and PCB 153) using three marine species (Vibrio fischeri, Tetraselmis suecica, and Tisbe battagliai). The sensitivity of each species varied for all compounds. The triorganotins were consistently the most toxic to all species. The applicability of each test system to assess the acute toxicity of environmental contaminants and their use in Toxicity Identification Evaluation (TIE) is discussed. Suitability of the Microtox and T. battagliai tests for employment in TIE studies were further assessed through spiking experiments with tributyltin. Results demonstrated that the most effective treatment to remove organotin toxicity from the sample was the C18 resin. The results of this study have important implications for risk assessment in estuarine and coastal waters in Ireland, where, at present the monitoring of sediment and water quality is predominantly reliant on chemical analysis alone. Ecotoxicological evaluation of five organic marine sediment contaminants was conducted and the suitability of the test species for marine porewater TIE discussed.
    • Modelling sympatric speciation by means of biologically plausible mechanistic processes as exemplified by threespine stickleback species pairs

      Kraak, Sarah Belle Mathilde; Hart, Paul J. B. (Springer, 2011)
      We investigate the plausibility of sympatric speciation through a modelling study. We built up a series of models with increasing complexity while focussing on questioning the realism of model assumptions by checking them critically against a particular biological system, namely the sympatric benthic and limnetic species of threespine stickleback in British Columbia, Canada. These are morphologically adapted to their feeding habits: each performs better in its respective habitat than do hybrids with intermediate morphology. Ecological character displacement through disruptive selection and competition, and reinforcement through mating preferences may have caused their divergence. Our model assumptions include continuous morphological trait(s) instead of a dimorphic trait, and mating preferences based on the same trait(s) as selected for in food competition. Initially, morphology is intermediate. We apply disruptive selection against intermediates, frequency-dependent resource competition, and one of two alternative mating preference mechanisms. Firstly, preference is based on similarity where mating preference may result from “imprinting” on conspecifics encountered in their preferred foraging habitat. Here, speciation occurs easily—ecological hybrid inferiority is not necessary. Hybrid inferiority reinforces the stringency of assortative mating. Secondly, individual preferences exist for different trait values. Here, speciation occurs when linkage disequilibrium between trait and preference develops, and some hybrid inferiority is required. Finally, if the morphology subject to disruptive selection, frequency-dependent competition, and mate choice, is coded for by two loci, linkage disequilibrium between the two loci is required for speciation. Speciation and reinforcement of stringency of choosiness are possible in this case too, but rarely. Results demonstrate the contingency of speciation, with the same starting point not necessarily producing the same outcome. The study resulted in flagging issues where models often lack in biological realism and issues where more empirical studies could inform on whether assumptions are likely valid.
    • Moving beyond the MSY concept to reflect multidimensional fisheries management objectives

      Rindorf, Anna; Mumford, John; Baranowski, Paul; Clausen, Lotte Worsøe; García, Dorleta; Hintzen, Niels T.; Kempf, Alexander; Leach, Adrian; Levontin, Polina; Mace, Pamela; et al. (Elsevier BV, 2017)
      Maximising the long term average catch of single stock fisheries as prescribed by the globally-legislated MSY objective is unlikely to ensure ecosystem, economic, social and governance sustainability unless an effort is made to explicitly include these considerations. We investigated how objectives to be maximised can be combined with sustainability constraints aiming specifically at one or more of these four sustainability pillars. The study was conducted as a three-year interactive process involving 290 participating science, industry, NGO and management representatives from six different European regions. Economic considerations and inclusive governance were generally preferred as the key objectives to be maximised in complex fisheries, recognising that ecosystem, social and governance constraints are also key aspects of sustainability in all regions. Relative preferences differed between regions and cases but were similar across a series of workshops, different levels of information provided and the form of elicitation methods used as long as major shifts in context or stakeholder composition did not occur. Maximising inclusiveness in governance, particularly the inclusiveness of affected stakeholders, was highly preferred by participants across the project. This suggests that advice incorporating flexibility in the interpretation of objectives to leave room for meaningful inclusiveness in decision-making processes is likely to be a prerequisite for stakeholder buy-in to management decisions.
    • A multi-proxy palaeolimnological study to reconstruct the evolution of a coastal brackish lake (Lough Furnace, Ireland) during the late Holocene

      Cassina, Filippo; Dalton, Catherine; Dillane, Mary; De Eyto, Elvira; Poole, Russell; Sparber, Karin (Elsevier, 2013)
      This study examines the evolution of Lough Furnace, a coastal brackish lake in the west of Ireland, using high-resolution sensors in the water column and palaeolimnological examination of the sediment archive. Palaeoenvironmental reconstructions suggest that meromixis formed as a result of sea level rise prior to ca. 4000 cal. yr BP. Increased seawater inflow has progressively led to permanent water stratification, which caused the onset of anoxia, making the monimolimnion a harsh environment for biological life. Diatom floristic interpretations suggest a progressive upcore increase in salinity, which is paralleled by a reduction in cladocera remains. Diagenetic processes have not altered the sediment organic matter signature. Organic matter mainly derives from freshwater DOC and appears to be linked to the presence of peat bogs in the catchment as confirmed by the C/N ratio. Upcore variations in the C/N ratio with a ca. 800-year periodicity have been interpreted as the result of alternating dry and wet climatic phases during the late Holocene, which appear synchronous with the NAO and long-term solar cycles. The current hydrology is largely controlled by freshwater inflow, which determines permanent meromictic conditions. Overturns are rare, requiring a specific combination of factors such as exceptionally dry and warm summers followed by cool autumns. According to the climate projections for the next century in Ireland, permanent meromictic conditions will probably continue.
    • A mussel tissue certified reference material for multiple phycotoxins. Part 1: design and preparation

      McCarron, P; Emteborg, H; Nulty, C; Rundberget, T; Loader, J I; Teipel, K; Miles, C O; Quilliam, M A; Hess, P (Springer Berlin / Heidelberg, 2011)
      The development of multi-analyte methods for lipophilic shellfish toxins based on liquid chromatography–mass spectrometry permits rapid screening and analysis of samples for a wide variety of toxins in a single run. To ensure accuracy of results, validated methods and appropriate certified reference materials (CRMs) are required. CRMs are essential for accurate instrument calibration, for assessing the complete analytical method from sample extraction to data analysis, and for verifying trueness. However, CRMs have hitherto only been available for single toxin groups. Production of a CRM containing six major toxin groups was achieved through an international collaboration. Preparation of this material, CRM-FDMT1, drew on information from earlier studies as well as improved methods for handling bulk tissues, production of reference materials, and isolation of toxins. Previous investigations of stabilisation techniques indicated freeze-drying to be a suitable procedure for preparation of shellfish toxin RMs and applicable to a wide range of toxins. CRM-FDMT1 was initially prepared as a bulk wet tissue homogenate with planned concentrations of domoic acid, okadaic acid, dinophysistoxins, azaspiracids, pectenotoxins, yessotoxin and spirolides. The homogenate was then freeze dried, milled and bottled in aliquots suitable for distribution and analysis. The moisture content and particle size distribution were measured, and determined to be appropriate. A preliminary toxin analysis of the final material showed a comprehensive toxin profile.
    • Natural selection acts on Atlantic salmon major histocompatibility (MH) variability in the wild

      de Eyto, E.; McGinnity, P.; Consuegra, S.; Coughlan, J.; Tufto, J.; Farrell, K.; Megens, H.J.; Jordan, W.; Cross, T.; Stet, R.J.M. (Royal Society Publishing, 2007)
      Pathogen-driven balancing selection is thought to maintain polymorphism in major histocompatibility (MH) genes. However, there have been few empirical demonstrations of selection acting on MH loci in natural populations. To determine whether natural selection on MH genes has fitness consequences for wild Atlantic salmon in natural conditions, we compared observed genotype frequencies of Atlantic salmon (Salmo salar) surviving in a river six months after their introduction as eggs with frequencies expected from parental crosses. We found significant differences between expected and observed genotype frequencies at the MH class II alpha locus, but not at a MH class I-linked microsatellite or at seven non-MH-linked microsatellite loci. We therefore conclude that selection at the MH class II alpha locus was a result of disease-mediated natural selection, rather than any demographic event. We also show that survival was associated with additive allelic effects at the MH class II alpha locus. Our results have implications for both the conservation of wild salmon stocks and the management of disease in hatchery fish. We conclude that natural or hatchery populations have the best chance of dealing with episodic and variable disease challenges if MH genetic variation is preserved both within and among populations.