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  • 1
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    Environmental requirements for three sea pen species: relevance to distribution and conservation (2015)
    Oxford University Press
    Details
    Publication Date: 2015-01-20
    Description: The aim is to determine the environmental requirements, estimate the extent of suitable habitat for three sea pen species, and assess the implications for marine protected areas (MPAs). The sea pen Funiculina quadrangularis and the habitat associated with two further sea pen species, Virgularia mirabilis and Pennatula phosphorea , are of key conservation importance and are recommended for protection within MPAs. This study models their potential distributions using the MAXimum ENTropy algorithm and assesses these in relation to five possible marine protected areas (pMPAs) proposed for Scottish waters. Metrics relevant to assessing the efficacy of MPAs are also presented. Four environmental variables of prime importance for predicting the presence of all three species of sea pen were identified: mud, minimum salinity, depth, and gravel. The habitat suitability index increased with mud content. The modelled distribution of F. quadrangularis indicated a deeper distribution than V. mirabilis or P. phosphorea and was not present in sediment with gravel content above 30%. Pennatula phosphorea had the smallest area of suitable habitat, while V. mirabilis had the largest. The percentage predicted suitable area for each species that was encompassed by the five pMPAs ranged from 11% for F. quadrangularis to 15% for P. phosphorea . Some of the largest areas predicted as suitable for F. quadrangularis lay outside the pMPAs. The model results indicated differences in the environmental requirements of the three species of sea pen that can be linked to the autecology of each species. Patch sizes, calculated from a binary output of the model, were used to estimate the degree of habitat fragmentation, thereby giving a partial assessment of the adequacy criterion for these pMPAs. The results suggest that potential MPAs within the study area cover sizeable areas of potential sea pen habitat. However, further areas suitable for F. quadrangularis could be considered.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press
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  • 2
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    Evaluating the effectiveness of a seasonal spawning area closure (2015)
    Oxford University Press
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    Publication Date: 2015-12-01
    Description: Fish that aggregate at predictable locations and times to spawn are often vulnerable to over-exploitation. Seasonal closures have often been implemented in an attempt to alleviate such impacts but the effectiveness of these measures is rarely tested. This study evaluates the effectiveness of a spawning closure for Atlantic cod ( Gadus morhua ) in the Firth of Clyde off the Scottish West Coast (ICES Area VIa). This closure was introduced in March 2001 as an emergency measure to allow as many cod as possible to spawn and avoid the build-up of displaced effort from another spawning closure. Genetic, tagging, and otolith microchemistry investigations indicate that cod inhabiting the Clyde are reproductively isolated from other resident groups in the central and northern part of the Scottish West Coast stock. This study used a beyond-Before-After, Control-Impact approach to compare population trends of the Clyde spawning aggregation before and after the introduced area closure, using two other sub-population spawning grounds as control areas. There was no evidence of local recovery in terms of abundance, biomass, or reduced mortality in the Clyde more than a decade after establishing the closure. Mortality may have remained high because young cod are still caught as bycatch in the Nephrops fishery in the area and the predation rate may have increased due to an expanding whiting population. Considering the state of the already severely depleted Clyde sub-population when the closure was implemented the measure appears to have been too little and too late. The tendency to implement such spawning closures on nearly collapsed stocks may be why these measures often appear to have been ineffective.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press
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  • 3
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    Spawning grounds of Atlantic cod (Gadus morhua) in the North Sea (2016)
    Oxford University Press
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    Publication Date: 2016-01-23
    Description: The protection of spawning fish from anthropogenic impacts requires information on the location, timing, and interannual persistence of spawning aggregations. In this study, generalized additive models were used to predict the spawning habitat of North Sea cod, based on the abundance of spawning fish within three population subareas and nine environmental layers. The length of spawning cod differed among population subareas, consistent with published evidence of maturation differences. In the northeast North Sea (Viking), the peak in the spawning season was estimated to occur after the survey which made the prediction of spawning grounds for this area less certain. Cod were found to prefer areas with temperatures around 5–7°C for spawning and there was a general preference for high salinity waters. Persistence of cod spawning grounds over the study period was related to interannual stability in temperature, with high variability in the use of Southern Bight spawning grounds. As such, cod appear to minimize interannual variability in the initial environmental conditions affecting offspring survival by selecting suitable cold spawning grounds. Seabed conditions also affected spawning distribution with cod selecting coarse sand and avoiding areas of very high tidal flow. The model prediction was compared with the distribution of cod aggregations during the spawning season reported by fishing boats. Seventy per cent of the aggregations was located in areas classified as occasional or recurrent spawning grounds. The predicted distribution confirmed the widespread occurrence of spawning in the North Sea and showed good agreement with recent and past studies of cod egg distribution, suggesting that nearly all major historical areas of spawning still appear in use today. However, the study also found that the recent recovery of spawning-stock biomass was not uniform across the stock, being centred in the northwest subarea.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press
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  • 4
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    A deep learning virtual instrument for monitoring extreme UV solar spectral irradiance (2019)
    American Association for the Advancement of Science (AAAS)
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    Publication Date: 2019
    Description: 〈p〉Measurements of the extreme ultraviolet (EUV) solar spectral irradiance (SSI) are essential for understanding drivers of space weather effects, such as radio blackouts, and aerodynamic drag on satellites during periods of enhanced solar activity. In this paper, we show how to learn a mapping from EUV narrowband images to spectral irradiance measurements using data from NASA’s Solar Dynamics Observatory obtained between 2010 to 2014. We describe a protocol and baselines for measuring the performance of models. Our best performing machine learning (ML) model based on convolutional neural networks (CNNs) outperforms other ML models, and a differential emission measure (DEM) based approach, yielding average relative errors of under 4.6% (maximum error over emission lines) and more typically 1.6% (median). We also provide evidence that the proposed method is solving this mapping in a way that makes physical sense and by paying attention to magnetic structures known to drive EUV SSI variability.〈/p〉
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
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    Observations of Reconnection Flows in a Flare on the Solar Disk (2017)
    Institute of Physics
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    Publication Date: 2017-09-13
    Print ISSN: 2041-8205
    Electronic ISSN: 2041-8213
    Topics: Physics
    Published by Institute of Physics
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  • 6
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    Understanding temperature effects on recruitment in the context of trophic mismatch (2019)
    Springer Nature
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    Publication Date: 2019-10-23
    Description: Understanding how temperature affects the relative phenology of predators and prey is necessary to predict climate change impacts and recruitment variation. This study examines the role of temperature in the phenology of a key forage fish, the lesser sandeel (Ammodytes marinus, Raitt) and its copepod prey. Using time-series of temperature, fish larval and copepod abundance from a Scottish coastal monitoring site, the study quantifies how thermal relationships affect the match between hatching in sandeel and egg production of its copepod prey. While sandeel hatch time was found to be related to the rate of seasonal temperature decline during the autumn and winter through effects on gonad and egg development, variation in copepod timing mostly responded to February temperature. These two temperature relationships defined the degree of trophic mismatch which in turn explained variation in local sandeel recruitment. Projected warming scenarios indicated an increasing probability of phenological decoupling and concomitant decline in sandeel recruitment. This study sheds light on the mechanisms by which future warming could increase the trophic mismatch between predator and prey, and demonstrates the need to identify the temperature-sensitive stages in predator-prey phenology for predicting future responses to climate change.
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
    Published by Springer Nature
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  • 7
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    Evaluating the effectiveness of a seasonal spawning area closure (2015)
    Oxford University Press
    Details
    Publication Date: 2015-08-12
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press on behalf of International Council for the Exploration of the Sea.
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  • 8
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    Integrating the scale of population processes into fisheries management, as illustrated in the sandeel, Ammodytes marinus (2019)
    Oxford University Press
    Details
    Publication Date: 2019-02-26
    Description: Aggregations of site-attached populations can show marked differences in density due to variation in local productivity and mortality processes. Matching management actions to the scale of biological processes is therefore important for sustainable fisheries management. This study examined the adequacy and appropriate scale of a spatially explicit management regime for sandeel, Ammodytes marinus, in the North Sea. Information from biophysical model simulations of larval transport and otolith chemistry was used to estimate the scale of mixing among aggregations. Together, these approaches indicated that there was negligible exchange of pre-settled sandeel among aggregations >200 km apart. Additionally, a re-analysis of tag-recapture experiments and distribution data indicated that the dispersive range decreased further after settlement. Significant differences in length at maturity and year-class strength not only reflect the limited mixing across the North Sea, but also point to regional differences in productivity and thereby vulnerability to fishing pressure. We conclude that the current management regime comprised of multiple assessment areas enable these differences to be considered in advice on annual fishing quotas.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press on behalf of International Council for the Exploration of the Sea.
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