ABSTRACT Phytoplankton phenology and primary production were examined in the Iceland–Faroe region... more ABSTRACT Phytoplankton phenology and primary production were examined in the Iceland–Faroe region through synthesis of all available data, both in situ and remotely sensed. In the Arctic water, the early onset of stratification in spring gave rise to the rapid shallowing of the mixed layer and triggered the earlier spring bloom north of Iceland, whereas the weakly stratified water-column in the Atlantic water and associated deep mixed layer delayed the spring bloom south of Iceland. The protocol (Nearest Neighbor Method, NNM) developed by Platt et al. (2008) was used to estimate the daily, water-column primary production from ocean color data. The key element of the procedure is an archived database, including (in this implementation) 505 sets of parameters of photosynthetic–light curves and 197 vertical profiles of chlorophyll around Iceland–Faroe region. The spatial structure in the climatology of annual primary production determined in this way was consistent with observations made by the simulated in situ method using ships as a platform, but, inevitably, the fields produced from the remotely sensed data were smoother. The annual primary production estimated by the NNM method overestimates the (much more sparse) data for in situ production by 50% on average. We examined the relative errors in the estimation of primary production that would arise from ignorance of the non-uniformity in the biomass profile. The vertically uniform model tended to underestimate the annual primary production by about 36% compared with the non-uniform model in a spectral calculation.
ABSTRACT Due to the unprecedented rate at which our climate is changing, the ultimate consequence... more ABSTRACT Due to the unprecedented rate at which our climate is changing, the ultimate consequence for many species is likely to be either extinction or migration to an alternate habitat. Certain species might, however, evolve at a rate that could make them resilient to the effects of a rapidly changing environment. This scenario is most likely to apply to species that have large population sizes and rapid generation times, such that the genetic variation required for adaptive evolution can be readily supplied. Emiliania huxleyi (Lohm.) Hay and Mohler (Prymnesiophyceae) is likely to be such a species as it is the most conspicuous extant calcareous phytoplankton species in our oceans with generation times of 1 day-1. Here we report on a validated set of microsatellites, in conjunction with the coccolithophore morphology motif genetic marker, to genotype 93 clonal isolates collected from across the world. Of these, 52 came from a single bloom event in the North Sea collected on the D366 UK Ocean Acidification cruise in June-July 2011. There were 26 multilocus genotypes (MLGs) encountered only once in the North Sea bloom and 8 MLGs encountered twice or up to six times. Each of these repeated MLGs exhibited Psex values of less than 0.05 indicating each repeated MLG was the product of asexual reproduction and not separate meiotic events. In addition, we show that the two most polymorphic microsatellite loci, EHMS37 and P01E05, are reporting on regions likely undergoing rapid genetic drift during asexual reproduction. Despite the small sample size, there were many more repeated genotypes than previously reported for other bloom-forming phytoplankton species, including a previously genotyped E. huxleyi bloom event. This study challenges our current assumption that sex is the predominant mode of reproduction during bloom events. Whilst genetic diversity is high amongst extant populations of E. huxleyi, the root cause for this diversity and ultimate fate of these populations still requires further examination. Nonetheless, we show that certain CMM genotypes are found everywhere; while others appear to have a regional bias.
Reaching over 12m in length, basking sharks (Cetorhinus maximus) are the largest fish in the Nort... more Reaching over 12m in length, basking sharks (Cetorhinus maximus) are the largest fish in the Northeast Atlantic and seasonally aggregate in UK coastal waters. Little is known about their behaviour during aggregations and as the rate of marine renewable energy development increases, there is an urgent need to develop resource-efficient platforms for monitoring basking sharks. Despite their size, quantifying their natural behaviour in plankton-rich waters remains a major challenge. Here, we present the successful application of a Teledyne RESON (Seabat 7128) multibeam sonar to track basking sharks at a key aggregation site on the West Coast of Scotland. First results of individual fine-scale tracking indicate that multibeam sonar is a promising tool for acoustic detection and tracking from a safe distance to the target species.
This paper introduces the NERC Earth Observation Data Acquisition and Analysis Service (NEODAAS) ... more This paper introduces the NERC Earth Observation Data Acquisition and Analysis Service (NEODAAS) a new facility combining two existing services, one at the University of Dundee (the Dundee Satellite Receiving Station) and at the other at Plymouth Marine Laboratory (the Remote Sensing Data Analysis Service). Activities undertaken by the new service are described ranging from direct-broadcast data received at Dundee to higher level processing at Plymouth. Examples include processing of sea-surface temperature and ocean colour data in support of UK marine observation, model validation and research cruises support; terrestrial and atmospheric products making use of the extensive archive of MODIS and AVHRR data available at the service. A new service for atmospheric correction of NERC airborne remote sensing imagery is presented along with proposed future services and an opportunity to influence further developments by NEODAAS.
Abstract A processing chain has been developed to download,the global MERIS level 2 seven day rol... more Abstract A processing chain has been developed to download,the global MERIS level 2 seven day rolling archive data and automatically map,them through the use of a GRID engine; data are available on the internet for CASIX investigators 20 minutes after the download,of the level 2 data. The first application of these data is the detection of phytoplankton functional types. A multivariate linear discriminant classifier has been successfully trained to discriminate spectral signatures of a selection of mono-specific algal bloom,species that are common,in the northeast Atlantic. These techniques are also being used in the EC DISMAR project. A second application is to support CASIX-related research cruises, as the use of the MERIS rolling archive allows near-real time global coverage. The techniques and methods used to create the mapped products, a description of the classifier and its training along with initial results are given.
ABSTRACT The European Slope Current (SC) is a major section of the warm poleward flow from the At... more ABSTRACT The European Slope Current (SC) is a major section of the warm poleward flow from the Atlantic to the Arctic, which also moderates the exchange of heat, salt, nutrients and carbon between the deep ocean and the European shelf seas. The mean structure of the geostrophic flow, seasonality, interannual variability and long-term trend of SC are appraised with an unprecedented continuous 20-year satellite altimeter dataset. Comparisons with long term in situ data showed a maximum correlation of r2 = 0.51 between altimeter and Acoustic Doppler Current Profilers (ADCP), with similar results for drogued buoy data. Mean geostrophic currents were appraised more comprehensively than previous attempts, and the paths of 4 branches of the North Atlantic Current (NAC) and positions of 5 eddies in the region were derived quantitatively. A consistent seasonal cycle in the flow of the SC was found at all 8 sections along the European shelf slope, with maximum poleward flow in the winter and minimum in the summer. The seasonal difference in the altimetry current speed amounted to ~ 8–10 cm s− 1 at the northern sections, but only ~ 5 cm s− 1 on the Bay of Biscay slopes. This extended altimeter dataset indicates significant regional and seasonal variations, and has revealed new insights into the interannual variability of the SC. It is shown that there is a peak poleward flow at most positions along a ~ 2000 km stretch of the continental slope from Portugal to Scotland during 1995–1997, but this did not clearly relate to the extreme negative North Atlantic Oscillation (NAO) in the winter of 1995–1996. The speed of the SC exhibited a long term decreasing trend of ~ 1% per year. By contrast the NAC showed no significant trend over the 20-year period. Major changes in the NAC occurred three times, and these changes followed decreases in the NAO index.
ABSTRACT Due to the unprecedented rate at which our climate is changing, the ultimate consequence... more ABSTRACT Due to the unprecedented rate at which our climate is changing, the ultimate consequence for many species is likely to be either extinction or migration to an alternate habitat. Certain species might, however, evolve at a rate that could make them resilient to the effects of a rapidly changing environment. This scenario is most likely to apply to species that have large population sizes and rapid generation times, such that the genetic variation required for adaptive evolution can be readily supplied. Emiliania huxleyi (Lohm.) Hay and Mohler (Prymnesiophyceae) is likely to be such a species as it is the most conspicuous extant calcareous phytoplankton species in our oceans with generation times of 1 day-1. Here we report on a validated set of microsatellites, in conjunction with the coccolithophore morphology motif genetic marker, to genotype 93 clonal isolates collected from across the world. Of these, 52 came from a single bloom event in the North Sea collected on the D366 UK Ocean Acidification cruise in June-July 2011. There were 26 multilocus genotypes (MLGs) encountered only once in the North Sea bloom and 8 MLGs encountered twice or up to six times. Each of these repeated MLGs exhibited Psex values of less than 0.05 indicating each repeated MLG was the product of asexual reproduction and not separate meiotic events. In addition, we show that the two most polymorphic microsatellite loci, EHMS37 and P01E05, are reporting on regions likely undergoing rapid genetic drift during asexual reproduction. Despite the small sample size, there were many more repeated genotypes than previously reported for other bloom-forming phytoplankton species, including a previously genotyped E. huxleyi bloom event. This study challenges our current assumption that sex is the predominant mode of reproduction during bloom events. Whilst genetic diversity is high amongst extant populations of E. huxleyi, the root cause for this diversity and ultimate fate of these populations still requires further examination. Nonetheless, we show that certain CMM genotypes are found everywhere; while others appear to have a regional bias.
Analysis of two years of QuikScat wind data in the Galician region has shown that the wind field ... more Analysis of two years of QuikScat wind data in the Galician region has shown that the wind field had high spatial and temporal variability year round. No clear seasonal signal was evident; upwelling and non-upwelling patterns alternated in all seasons. Two outstanding features of the Galician region are persistent upwelling near Cape Finisterre even when not present further south and
ABSTRACT 1.Understanding the mechanisms linking oceanographic processes and marine vertebrate spa... more ABSTRACT 1.Understanding the mechanisms linking oceanographic processes and marine vertebrate space use is critical to our knowledge of marine ecosystem functioning, and for effective management of populations of conservation concern. 2.The basking shark Cetorhinus maximus has been observed in association with oceanographic fronts – physical interfaces at the transitions between water masses – exploiting foraging opportunities resulting from zooplankton aggregation. However, the scale, significance and variability of these associations have not previously been established. 3.Here, we quantify the influence of thermal and chlorophyll-a fronts on basking shark habitat use in the northeast Atlantic. We use animal-mounted archival tracking with composite front mapping via Earth Observation (EO) remote sensing to provide an oceanographic context to individual shark movements. 4.We investigate levels of association with fronts occurring over two spatio-temporal scales, (i) broad-scale, seasonally persistent frontal zones and (ii) contemporaneous thermal and chl-a fronts. Using random walk simulations and logistic regression within an iterative generalised linear mixed modelling (GLMM) framework, we find that seasonal front frequency is a significant predictor of shark presence. 5.Oceanographic metrics time-matched to shark tracks indicate that sharks show a preference for productive regions, and associate with contemporaneous thermal and chl-a fronts more frequently than could be expected at random. Moreover, we highlight the importance of front persistence and cross-frontal temperature step, which appear to interact to affect the degree of prey aggregation along thermal fronts in this shelf-sea system. 6.Our findings confirm that surface frontal activity is a predictor of basking shark presence in the northeast Atlantic, both over seasonal timescales and in near real-time. These insights have clear implications for understanding the preferred habitats of basking sharks in the context of anthropogenic threat management and marine spatial planning in the region. Miller and Scales are joint first authors. This article is protected by copyright. All rights reserved.
International Journal of Pattern Recognition and Artificial Intelligence, 1993
Mammographic screening programmes generate large numbers of highly variable, complex images, most... more Mammographic screening programmes generate large numbers of highly variable, complex images, most of which are unequivocally normal. When present, abnorma lities may be small or subtle. Two processes critical to the success of screening programmes are the perception of potential abnormalities and the subsequent analysis of each detected lesion to determine its clinical significance. The consequences of errors are costly,
ABSTRACT Phytoplankton phenology and primary production were examined in the Iceland–Faroe region... more ABSTRACT Phytoplankton phenology and primary production were examined in the Iceland–Faroe region through synthesis of all available data, both in situ and remotely sensed. In the Arctic water, the early onset of stratification in spring gave rise to the rapid shallowing of the mixed layer and triggered the earlier spring bloom north of Iceland, whereas the weakly stratified water-column in the Atlantic water and associated deep mixed layer delayed the spring bloom south of Iceland. The protocol (Nearest Neighbor Method, NNM) developed by Platt et al. (2008) was used to estimate the daily, water-column primary production from ocean color data. The key element of the procedure is an archived database, including (in this implementation) 505 sets of parameters of photosynthetic–light curves and 197 vertical profiles of chlorophyll around Iceland–Faroe region. The spatial structure in the climatology of annual primary production determined in this way was consistent with observations made by the simulated in situ method using ships as a platform, but, inevitably, the fields produced from the remotely sensed data were smoother. The annual primary production estimated by the NNM method overestimates the (much more sparse) data for in situ production by 50% on average. We examined the relative errors in the estimation of primary production that would arise from ignorance of the non-uniformity in the biomass profile. The vertically uniform model tended to underestimate the annual primary production by about 36% compared with the non-uniform model in a spectral calculation.
ABSTRACT Due to the unprecedented rate at which our climate is changing, the ultimate consequence... more ABSTRACT Due to the unprecedented rate at which our climate is changing, the ultimate consequence for many species is likely to be either extinction or migration to an alternate habitat. Certain species might, however, evolve at a rate that could make them resilient to the effects of a rapidly changing environment. This scenario is most likely to apply to species that have large population sizes and rapid generation times, such that the genetic variation required for adaptive evolution can be readily supplied. Emiliania huxleyi (Lohm.) Hay and Mohler (Prymnesiophyceae) is likely to be such a species as it is the most conspicuous extant calcareous phytoplankton species in our oceans with generation times of 1 day-1. Here we report on a validated set of microsatellites, in conjunction with the coccolithophore morphology motif genetic marker, to genotype 93 clonal isolates collected from across the world. Of these, 52 came from a single bloom event in the North Sea collected on the D366 UK Ocean Acidification cruise in June-July 2011. There were 26 multilocus genotypes (MLGs) encountered only once in the North Sea bloom and 8 MLGs encountered twice or up to six times. Each of these repeated MLGs exhibited Psex values of less than 0.05 indicating each repeated MLG was the product of asexual reproduction and not separate meiotic events. In addition, we show that the two most polymorphic microsatellite loci, EHMS37 and P01E05, are reporting on regions likely undergoing rapid genetic drift during asexual reproduction. Despite the small sample size, there were many more repeated genotypes than previously reported for other bloom-forming phytoplankton species, including a previously genotyped E. huxleyi bloom event. This study challenges our current assumption that sex is the predominant mode of reproduction during bloom events. Whilst genetic diversity is high amongst extant populations of E. huxleyi, the root cause for this diversity and ultimate fate of these populations still requires further examination. Nonetheless, we show that certain CMM genotypes are found everywhere; while others appear to have a regional bias.
Reaching over 12m in length, basking sharks (Cetorhinus maximus) are the largest fish in the Nort... more Reaching over 12m in length, basking sharks (Cetorhinus maximus) are the largest fish in the Northeast Atlantic and seasonally aggregate in UK coastal waters. Little is known about their behaviour during aggregations and as the rate of marine renewable energy development increases, there is an urgent need to develop resource-efficient platforms for monitoring basking sharks. Despite their size, quantifying their natural behaviour in plankton-rich waters remains a major challenge. Here, we present the successful application of a Teledyne RESON (Seabat 7128) multibeam sonar to track basking sharks at a key aggregation site on the West Coast of Scotland. First results of individual fine-scale tracking indicate that multibeam sonar is a promising tool for acoustic detection and tracking from a safe distance to the target species.
This paper introduces the NERC Earth Observation Data Acquisition and Analysis Service (NEODAAS) ... more This paper introduces the NERC Earth Observation Data Acquisition and Analysis Service (NEODAAS) a new facility combining two existing services, one at the University of Dundee (the Dundee Satellite Receiving Station) and at the other at Plymouth Marine Laboratory (the Remote Sensing Data Analysis Service). Activities undertaken by the new service are described ranging from direct-broadcast data received at Dundee to higher level processing at Plymouth. Examples include processing of sea-surface temperature and ocean colour data in support of UK marine observation, model validation and research cruises support; terrestrial and atmospheric products making use of the extensive archive of MODIS and AVHRR data available at the service. A new service for atmospheric correction of NERC airborne remote sensing imagery is presented along with proposed future services and an opportunity to influence further developments by NEODAAS.
Abstract A processing chain has been developed to download,the global MERIS level 2 seven day rol... more Abstract A processing chain has been developed to download,the global MERIS level 2 seven day rolling archive data and automatically map,them through the use of a GRID engine; data are available on the internet for CASIX investigators 20 minutes after the download,of the level 2 data. The first application of these data is the detection of phytoplankton functional types. A multivariate linear discriminant classifier has been successfully trained to discriminate spectral signatures of a selection of mono-specific algal bloom,species that are common,in the northeast Atlantic. These techniques are also being used in the EC DISMAR project. A second application is to support CASIX-related research cruises, as the use of the MERIS rolling archive allows near-real time global coverage. The techniques and methods used to create the mapped products, a description of the classifier and its training along with initial results are given.
ABSTRACT The European Slope Current (SC) is a major section of the warm poleward flow from the At... more ABSTRACT The European Slope Current (SC) is a major section of the warm poleward flow from the Atlantic to the Arctic, which also moderates the exchange of heat, salt, nutrients and carbon between the deep ocean and the European shelf seas. The mean structure of the geostrophic flow, seasonality, interannual variability and long-term trend of SC are appraised with an unprecedented continuous 20-year satellite altimeter dataset. Comparisons with long term in situ data showed a maximum correlation of r2 = 0.51 between altimeter and Acoustic Doppler Current Profilers (ADCP), with similar results for drogued buoy data. Mean geostrophic currents were appraised more comprehensively than previous attempts, and the paths of 4 branches of the North Atlantic Current (NAC) and positions of 5 eddies in the region were derived quantitatively. A consistent seasonal cycle in the flow of the SC was found at all 8 sections along the European shelf slope, with maximum poleward flow in the winter and minimum in the summer. The seasonal difference in the altimetry current speed amounted to ~ 8–10 cm s− 1 at the northern sections, but only ~ 5 cm s− 1 on the Bay of Biscay slopes. This extended altimeter dataset indicates significant regional and seasonal variations, and has revealed new insights into the interannual variability of the SC. It is shown that there is a peak poleward flow at most positions along a ~ 2000 km stretch of the continental slope from Portugal to Scotland during 1995–1997, but this did not clearly relate to the extreme negative North Atlantic Oscillation (NAO) in the winter of 1995–1996. The speed of the SC exhibited a long term decreasing trend of ~ 1% per year. By contrast the NAC showed no significant trend over the 20-year period. Major changes in the NAC occurred three times, and these changes followed decreases in the NAO index.
ABSTRACT Due to the unprecedented rate at which our climate is changing, the ultimate consequence... more ABSTRACT Due to the unprecedented rate at which our climate is changing, the ultimate consequence for many species is likely to be either extinction or migration to an alternate habitat. Certain species might, however, evolve at a rate that could make them resilient to the effects of a rapidly changing environment. This scenario is most likely to apply to species that have large population sizes and rapid generation times, such that the genetic variation required for adaptive evolution can be readily supplied. Emiliania huxleyi (Lohm.) Hay and Mohler (Prymnesiophyceae) is likely to be such a species as it is the most conspicuous extant calcareous phytoplankton species in our oceans with generation times of 1 day-1. Here we report on a validated set of microsatellites, in conjunction with the coccolithophore morphology motif genetic marker, to genotype 93 clonal isolates collected from across the world. Of these, 52 came from a single bloom event in the North Sea collected on the D366 UK Ocean Acidification cruise in June-July 2011. There were 26 multilocus genotypes (MLGs) encountered only once in the North Sea bloom and 8 MLGs encountered twice or up to six times. Each of these repeated MLGs exhibited Psex values of less than 0.05 indicating each repeated MLG was the product of asexual reproduction and not separate meiotic events. In addition, we show that the two most polymorphic microsatellite loci, EHMS37 and P01E05, are reporting on regions likely undergoing rapid genetic drift during asexual reproduction. Despite the small sample size, there were many more repeated genotypes than previously reported for other bloom-forming phytoplankton species, including a previously genotyped E. huxleyi bloom event. This study challenges our current assumption that sex is the predominant mode of reproduction during bloom events. Whilst genetic diversity is high amongst extant populations of E. huxleyi, the root cause for this diversity and ultimate fate of these populations still requires further examination. Nonetheless, we show that certain CMM genotypes are found everywhere; while others appear to have a regional bias.
Analysis of two years of QuikScat wind data in the Galician region has shown that the wind field ... more Analysis of two years of QuikScat wind data in the Galician region has shown that the wind field had high spatial and temporal variability year round. No clear seasonal signal was evident; upwelling and non-upwelling patterns alternated in all seasons. Two outstanding features of the Galician region are persistent upwelling near Cape Finisterre even when not present further south and
ABSTRACT 1.Understanding the mechanisms linking oceanographic processes and marine vertebrate spa... more ABSTRACT 1.Understanding the mechanisms linking oceanographic processes and marine vertebrate space use is critical to our knowledge of marine ecosystem functioning, and for effective management of populations of conservation concern. 2.The basking shark Cetorhinus maximus has been observed in association with oceanographic fronts – physical interfaces at the transitions between water masses – exploiting foraging opportunities resulting from zooplankton aggregation. However, the scale, significance and variability of these associations have not previously been established. 3.Here, we quantify the influence of thermal and chlorophyll-a fronts on basking shark habitat use in the northeast Atlantic. We use animal-mounted archival tracking with composite front mapping via Earth Observation (EO) remote sensing to provide an oceanographic context to individual shark movements. 4.We investigate levels of association with fronts occurring over two spatio-temporal scales, (i) broad-scale, seasonally persistent frontal zones and (ii) contemporaneous thermal and chl-a fronts. Using random walk simulations and logistic regression within an iterative generalised linear mixed modelling (GLMM) framework, we find that seasonal front frequency is a significant predictor of shark presence. 5.Oceanographic metrics time-matched to shark tracks indicate that sharks show a preference for productive regions, and associate with contemporaneous thermal and chl-a fronts more frequently than could be expected at random. Moreover, we highlight the importance of front persistence and cross-frontal temperature step, which appear to interact to affect the degree of prey aggregation along thermal fronts in this shelf-sea system. 6.Our findings confirm that surface frontal activity is a predictor of basking shark presence in the northeast Atlantic, both over seasonal timescales and in near real-time. These insights have clear implications for understanding the preferred habitats of basking sharks in the context of anthropogenic threat management and marine spatial planning in the region. Miller and Scales are joint first authors. This article is protected by copyright. All rights reserved.
International Journal of Pattern Recognition and Artificial Intelligence, 1993
Mammographic screening programmes generate large numbers of highly variable, complex images, most... more Mammographic screening programmes generate large numbers of highly variable, complex images, most of which are unequivocally normal. When present, abnorma lities may be small or subtle. Two processes critical to the success of screening programmes are the perception of potential abnormalities and the subsequent analysis of each detected lesion to determine its clinical significance. The consequences of errors are costly,
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Papers by Peter I Miller