Excitable interplay between lasing quantum dot states

The optically injected semiconductor laser system has proven to be an excellent source of experimental nonlinear dynamics, particularly regarding the generation of excitable pulses. Typically for low-injection strengths, these pulses are the result of a small above-threshold perturbation of a stable steady state, the underlying physics is well described by the Adler phase equation, and each laser intensity pulse is accompanied by a 2π phase rotation. In this article, we show how, with a dual-state quantum dot laser, a variation of type I excitability is possible that cannot be described by the Adler model. The laser is operated so that emission is from the excited state only. The ground state can be activated and phase locked to the master laser via optical injection while the excited state is completely suppressed. Close to the phase-locking boundary, a region of ground-state emission dropouts correlated to excited-state pulses can be observed. We show that the phase of the ground state undergoes bounded rotations due to interactions with the excited state. We analyze the system both experimentally and numerically and find excellent agreement. Particular attention is devoted to the bifurcation conditions needed for an excitable pulse as well as its time evolution

False‐negative detections from environmental DNA collected in the presence of large numbers of killer whales (Orcinus orca)

While environmental DNA (eDNA) is becoming increasingly established in biodiversity monitoring of freshwater ecosystems, the use of eDNA surveys in the marine environment is still in its infancy. Here, we use two approaches: targeted quantitative PCR (qPCR) and whole-genome enrichment capture followed by shotgun sequencing in an effort to amplify killer whale DNA from seawater samples. Samples were collected in close proximity to killer whales in inshore and offshore waters, in varying sea conditions and from the surface and subsurface but none returned strongly positive detections of killer whale eDNA. We validated our laboratory methodologies by successfully amplifying a dilution series of a positive control of killer whale DNA. Furthermore, DNA of Atlantic mackerel, which was present at all sites during sampling, was successfully amplified from the same seawater samples, with positive detections found in ten of the eighteen eDNA extracts. We discuss the various eDNA collection and amplification methodologies used and the abiotic and biotic factors that influence eDNA detection. We discuss possible explanations for the lack of positive killer whale detections, potential pitfalls, and the apparent limitations of eDNA for genetic research on cetaceans, particularly in offshore regions

Improving abundance estimates from electrofishing removal sampling

Estimates of fish abundance from electrofishing surveys depend on accurate estimation of capture probability. We examine in this paper how estimates of capture probability and abundance of Atlantic salmon from multi-pass removal sampling can be improved by comparing the results of an experimental programme of closed electrofishing sites within selected rivers in west-central Norway, and those obtained from open electrofishing sites established for monitoring long-term juvenile Atlantic salmon population abundance within the Burrishoole catchment, western Ireland. We first establish that the Carle & Strub method provides a more robust estimate of population abundance than the Zippin and Seber methods. We then show how prior information on capture probability may be used to improve the accuracy of the abundance estimate in open sites. We also show that the use of prior information with single-pass electrofishing may improve the accuracy of the abundance estimate so that it is comparable with that of multi-pass electrofishing in terms of stock prediction while requiring less sampling effortSupported by Norwegian Institute for Nature Research, the Norwegian Directorate for Nature, and the Beaufort Marine Research Award in Fish Population Genetics funded by the Irish Government under the Sea Change Programme

Anthropocene environmental change in an internationally important oligotrophic catchment on the Atlantic seaboard of western Europe

Oligotrophic catchments with short spatey streams, upland lakes and peaty soils characterise northwest European Atlantic coastal regions. These catchments are important biodiversity refuges, particularly for sensitive diadromous fish populations but are subject to changes in land use and land management practices associated with afforestation, agriculture and rural development. Quantification of the degree of catchment degradation resulting from such anthropogenic impacts is often limited by a lack of long-term baseline data in what are generally relatively isolated, poorly studied catchments. This research uses a combination of palaeolimnological (radiometrically-dated variations in sedimentary geochemical elements, pollen, diatoms and remains of cladocera), census, and instrumental data, along with hindcast estimates to quantify environmental changes and their aquatic impacts since the late 19th century. The most likely drivers of any change are also identified. Results confirm an aquatic biotic response (phyto- and zooplankton) to soil erosion and nutrient enrichment associated with the onset of commercial conifer afforestation, effects that were subsequently enhanced as a result of increased overgrazing in the catchment and, possibly, climate warming. The implications for the health of aquatic resources in the catchment are discussedEnvironmental Protection Agency in Ireland (ILLUMINATE 2005-W-MS-40, P.McGinnity was supported by the Beaufort Marine Research Award in Fish Population Genetics funded by the Irish Government under the Sea Change Programme

The response of North Atlantic diadromous fish to multiple stressors including land use change: a multidecadal study

This is a author-produced PDF of a 'Just in' article published in Canadian Journal of Fisheries and Aquatic Sciences following peer review. The definitive publisher-authenticated version 'The response of North Atlantic diadromous fish to multiple stressors including land use change: a multidecadal study Elvira de Eyto, Catherine Dalton, Mary M Dillane, Eleanor Jennings, Philip McGinnity, Barry O'Dwyer, Russell Poole, Ger G Rogan, David Taylor Canadian Journal of Fisheries and Aquatic Sciences, Published on the web 19 May 2016, 10.1139/cjfas-2015-0450' is available from DOI 10.1139/cjfas-2015-0450'Reduction of freshwater habitat quality due to land use change can have significant impacts on diadromous fish. Partitioning this impact from other potential drivers, such as changing marine conditions and climate, is hampered by a lack of long term datasets. Here, four decades of data were used to assess the impact of land use change on Salmo salar L. and anadromous Salmo trutta L. in the Burrishoole catchment, Ireland, one of the few index sites for diadromous fish in the North Atlantic. Land use change was found to have no significant impact on the freshwater survival of either salmon or trout. However, climate impacted significantly on the survival of salmon and trout in freshwater, with poor survival in years with wetter warmer winters, coinciding with positive North Atlantic Oscillation values. Additionally, cold springs were associated with higher survival in trout. The addition of hatchery salmon into the salmon spawning cohort coincided with low freshwater survival. Our results highlight the necessity for a broad ecosystem approach in any conservation effort of these species

RESCALE: Review and Simulate Climate and Catchment Responses at Burrishoole

The climate of the Burrishoole catchment is projected to change significantly over the present century. Previous research of the catchment identified a scientific gap in knowledge in terms of understanding the implications of present and projected future changes in stream flow, water temperature, pH levels and DO concentrations on fish productivity in the catchment. To address this, a multidisciplinary team of scientists undertook an analysis of both present and likely future climate impacts on the catchment with a view to furthering the understanding of the inter-linkages between climate, climate change, and the freshwater ecosystem. The research findings outlined in the report provide climate change information at the catchment scale to assist catchment stakeholders in integrating climate change considerations into their decision-making processes. The report presents an in-depth assessment of the climate and environmental datasets from the catchment to establish if changes have occurred over the period of record. In order to assess the likely impacts of future changes in climate on the catchment, regional climate projections were developed and subsequently employed to simulate likely responses in stream flow and temperature, DOC and DO for the present century. The projected changes in both the climate and water-quality were then used to provide a basis for assessing impacts on fish growth and survival rates of salmonid and eel species in the catchment. The report provides a useful template for future studies, not just in the Burrishoole catchment but for other ecologically important catchments. The findings from the report are relevant to policy makers at the national scale; catchment managers at the regional scale; and, specifically, to stakeholders in the Burrishoole catchment, in developing adaptive responses to climate change.Funded under the Marine Research Sub-programme of the National Development Plan (2007-’13), as part of the Sea Change Strategy.Funder: Marine Institut

Technical Report: Review and Simulate Climate and Catchment Responses at Burrishoole (RESCALE)

Lead Partner: Department of Geography, National University of Ireland Maynooth Project Partners: School of Natural Sciences, Trinity College Dublin Marine Institute, Furnace, Newport, Co. MayoThis report demonstrates that the projected changes in the climate conditions of the Burrishoole catchment, if realised, will have wide ranging implications for all aspects of the catchment system, including water temperature and quality, stream flow hydrology, soil processes, and most notably the well-being of its aquatic environment. While the projected changes in climate and their implications, outlined in this report, are specific to the Burrishoole, they are illustrative of likely changes in similar characteristic catchments along the west coast of Ireland.Funder: Marine Institut

The Troubled Families Programme : learning about policy impact through realist case study research

This article aims to critically explore how qualitative case study research that is founded on realist principles can fundamentally enhance social policy evaluation methodologies and, in turn, provide improved learning for policy makers and practitioners. We suggest these methodological advantages are accrued through the careful construction of theory-based explanations of 'how' policy programmes work thereby addressing the limitations of quasiexperimental methods - namely a focus on and prioritisation of outcome measures. The paper situates this key argument within wider, long-standing debates about evidence-based policy-making and what constitutes 'evidence' of impact in social policy. It does so through reflection on the contentious and contradictory knowledge claims that surround the Troubled Families Programme and evaluative claims regarding its efficacy. In conclusion and looking forward, we suggest that there remains much scope to combine 'intensive' qualitative case studies with 'extensive' quantitative measures within local and national evaluations of complex, multi-dimensional social policies, such as the Troubled Families Programme