• Early detection of an emerging invasive species: eDNA monitoring of a parthenogenetic crayfish in freshwater systems

      Mauvisseau, Quentin; Sweet, Michael; Lyko, Frank; Andriantsoa, Ranja; Tonges, Sina; University of Derby; Surescreen Scientifics Ltd, Morley; German Cancer Research Center, Germany (Regional Euro-Asian Biological Invasions Centre Oy (REABIC), 2019-06-06)
      Procambarus virginalis, also known as the Marmorkrebs is a highly invasive crayfish species characterized by parthenogenetic reproduction. As conservation management plans rely on the accuracy of the presence and distribution information of invasive species, a reliable method is needed for detecting such species in aquatic systems. We developed and validated a qPCR-based assay for monitoring P. virginalis at low abundance, by detecting their eDNA traces left in freshwater systems. We were able to implement this new assay in-situ at two separate lakes in Germany, where the crayfish were known to be present. Furthermore, we did not detect the pathogenic fungus Aphanomyces astaci in the locations where the Marmorkrebs were detected. We conclude that the use of eDNA is therefore a reliable tool for the early detection of this “perfect invader”.
    • Ecological role of vertebrate scavengers in urban ecosystems in the UK

      Inger, Richard; Cox, Daniel, T. C.; Per, Esra; Norton, Briony, A.; Gaston, Kevin J.; University of Exeter; Gazi University; University of Sheffield (Wiley, 2016-10)
      Recent research has demonstrated how scavenging, the act of consuming dead animals, plays a key role in ecosystem structure, functioning, and stability. A growing number of studies suggest that vertebrate scavengers also provide key ecosystem services, the benefits humans gain from the natural world, particularly in the removal of carcasses from the environment. An increasing proportion of the human population is now residing in cities and towns, many of which, despite being highly altered environments, contain significant wildlife populations, and so animal carcasses. Indeed, non-predation fatalities may be higher within urban than natural environments. Despite this, the fate of carcasses in urban environments and the role vertebrate scavengers play in their removal have not been determined. In this study, we quantify the role of vertebrate scavengers in urban environments in three towns in the UK. Using experimentally deployed rat carcasses and rapid fire motion-triggered cameras, we determined which species were scavenging and how removal of carcass biomass was partitioned between them. Of the 63 experimental carcasses deployed, vertebrate scavenger activity was detected at 67%. There was a significantly greater depletion in carcass biomass in the presence (mean loss of 194 g) than absence (mean loss of 14 g) of scavengers. Scavenger activity was restricted to three species, Carrion crows Corvus corone, Eurasian magpies Pica pica, and European red foxes Vulpes vulpes. From behavioral analysis, we estimated that a maximum of 73% of the carcass biomass was removed by vertebrate scavengers. Despite having low species richness, the urban scavenger community in our urban study system removed a similar proportion of carcasses to those reported in more pristine environments. Vertebrate scavengers are providing a key urban ecosystem service in terms of carcass removal. This service is, however, often overlooked, and the species that provide it are among some of the most disliked and persecuted.
    • Editorial: Coral Reefs in the Anthropocene – Reflecting on 20 Years of Reef Conservation UK

      Andradi-Brown, Dominic A.; Banaszak, Anastazia T.; Frazer, Thomas K.; Gilchrist, Hannah; Harborne, Alastair R.; Head, Catherine E. I.; Koldewey, Heather J.; Levy, Emma; Richards, Kirsty; Short, Rebecca; et al. (Frontiers Media SA, 2020-06-12)
      Editorial on the Research Topic Coral Reefs in the Anthropocene – Reflecting on 20 Years of Reef Conservation UK.
    • The effect of urban ground covers on arthropods: An experiment.

      Norton, Briony, A.; Thomson, Linda J.; Williams, Nicholas S. G.; McDonnell, Mark J.; University of Melbourne; Royal Botanic Gardens Melbourne (Springer, 2013-02-14)
      Changes to the ground layer in urban areas are extensive, but the effects on arthropod fauna are poorly understood. We undertook a manipulative experiment to examine the response of arthropods to small-scale variation in ground covers commonly found in urban parks and gardens in Australia. The ground covers tested were bare ground, leaf litter, woodchips and grass, with plot sizes of 3.6 m2. Epigeic arthropods were sampled with pitfall traps and Tullgren funnels over 12 months following establishment of the treatments. All epigeic arthropods were sorted to order and the ants (Hymenoptera: Formicidae), beetles (Coleoptera), millipedes (Diplopoda) and slaters (Isopoda: Oniscidea) were examined at lower taxonomic levels. Diverse arthropods rapidly colonised previously cleared plots in all four treatments and were most abundant in grass plots. The diversity of ants and beetles was significantly different in different ground covers and tended to be most diverse in grass plots. Despite the treatments providing very different microclimates, the fauna studied did not show strong selection for a particular cover type overall. The abundance of grass cover in the surrounding area may have led to the grass plots having the greatest abundance of arthropods. These results have important implications for developing effective small-scale conservation efforts for arthropods in anthropogenically modified landscapes, especially for species with poor dispersal abilities.
    • Effects of environmental temperature on oviposition behavior in three blow fly species of forensic importance

      Ody, Helen; Bulling, Mark T.; Barnes, Kate M.; University of Derby (Elsevier, 2017-03-14)
      A number of factors are known to affect blow fly behavior with respect to oviposition. Current research indicates that temperature is the most significant factor. However temperature thresholds for oviposition in forensically important blow flies have not been well studied. Here, the oviposition behavior of three species of forensically important blow fly species (Calliphora vicina, Calliphora vomitoria and Lucilia sericata,) was studied under controlled laboratory conditions over a range of temperatures (10 to 40°C). Lower temperature thresholds for oviposition of 16°C and 17.5°C were established for C. vomitoria and L. sericata respectively, whilst C. vicina continued to lay eggs at 10°C. C. vomitoria and L. sericata both continued to lay eggs at 40°C, whilst the highest temperature at which oviposition occurred in C. vicina was 35°C. Within these thresholds there was considerable variation in the number of surviving pupae, with a general pattern of a single peak within the range of temperatures at which eggs were laid, but with the pattern being much less distinct for L. sericata
    • Effects of substrate size and cleaning regime on growth and survival of captive-bred juvenile freshwater pearl mussels, Margaritifera margaritifera (Linnaeus, 1758)

      Lavictoire, Louise; Sinclair, William; Sweeting, Roger A.; Moorkens, Evelyn; Ramsey, Andrew; University of Derby (Springer, 2015-09-04)
      The freshwater pearl mussel is critically endangered and most English populations are at risk of extinction unless conservation measures are implemented immediately. The study objectives were to test a culture system for rearing Margaritifera margaritifera in captivity, and to investigate the effects of substrate size (0.25–1 and 1–2 mm) and cleaning regime (weekly and monthly) on survival and growth. In total, 1207 and 518 juveniles were reared to 362 (12 months) and 758 days (25 months), respectively. After 362 days, survival was significantly higher in 1–2 mm substrate treatments cleaned monthly (55 ± 6 %) and lowest in 0.25–1 mm substrate cleaned weekly (14 ± 3 %). Growth was significantly higher in 1–2 mm substrates cleaned weekly (length = 1.15 ± 0.21 mm) and lowest in 0.25–1 mm substrates cleaned monthly (length = 0.83 ± 0.23 mm). Juveniles from most treatments did not display sizedependent over-winter survival, but a significant correlation was found between shell length and survival in the 0.25–1 mm weekly treatment. This low-maintenance system utilised features of previously described systems and growth and survival rates were comparable to, if not better than, other studies culturing M. margaritifera. The system could be scaled up to rear significant numbers of juveniles in captivity.
    • Elemental ratios link environmental change and human health

      Paseka, Rachel E.; Bratt, Anika R.; MacNeill, Keeley L.; Burian, Alfred; See, Craig R.; University of Derby (Frontiers, 2019-10-10)
      Humans have fundamentally altered the cycling of multiple elements on a global scale. These changes impact the structure and function of terrestrial and aquatic ecosystems, with many implications for human health. Most prior studies linking biogeochemical changes to human health have evaluated the effects of single elements in isolation. However, the relative availability of multiple elements often determines the biological impact of shifts in the concentration of a single element. The balance of multiple elements is the focus of ecological stoichiometry, which highlights the importance of elemental ratios in biological function across all systems and scales of organization. Consequently, ecological stoichiometry is a promising framework to inform research on the links between global changes to elemental cycles and human health. We synthesize evidence that elemental ratios link global change with human health through biological processes occurring at two scales: in the environment (natural ecosystems and food systems) and within the human body. Elemental ratios in the environment impact the key ecosystem processes of productivity and biodiversity, both of which contribute to the production of food, toxins, allergens, and parasites. Elemental ratios in diet impact processes within the human body, including the function and interactions of the immune system, parasites, and the non-pathogenic microbiome. Collectively, these stoichiometric effects contribute to a wide range of non-infectious and infectious diseases. By describing stoichiometric mechanisms linking global change, ecological processes, and human health, we hope to inspire future empirical and theoretical research on this theme.
    • Emerging issues in the evolution of animal nuptial gifts

      Lewis, Sara M.; Vahed, Karim; Koene, Joris M.; Bussiere, Luc F.; Gwynne, Darryl; Engqvist, Leif; Perry, Jennifer; Lehmann, Gerlind; Tufts University, Medford MA USA; University of Derby (The Royal Society, 2014-07-16)
      Uniquely positioned at the intersection of sexual selection, nutritional ecology and life-history theory, nuptial gifts are widespread and diverse. Despite extensive empirical study, we still have only a rudimentary understanding of gift evolution because we lack a unified conceptual framework for considering these traits. In this opinion piece, we tackle several issues that we believe have substantively hindered progress in this area. Here, we: (i) present a comprehensive definition and classification scheme for nuptial gifts (including those transferred by simultaneous hermaphrodites), (ii) outline evolutionary predictions for different gift types, and (iii) highlight some research directions to help facilitate progress in this field.
    • Endemicity and climatic niche differentiation in three marine ciliated protists

      Williams, Richard; Owens, Hannah L; Clamp, John; Peterson, A Townsend; Warren, Alan; Martin-Cereceda, Mercedes; Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus University, SE-391 82, Kalmar, Sweden; Biodiversity Institute, University of Kansas, Lawrence, KS 66045, USA; Department of Biodiversity, Ecology and Evolution, Universidad Complutense de Madrid, 28040, Madrid, Spain; Department of Biology, University of Florida, Gainesville, FL 32611, USA; et al. (Association for the Sciences of Limnology and Oceanography (ASLO), 2018-07-18)
      The biogeographic pattern of single‐celled eukaryotes (protists), including ciliates, is poorly understood. Most marine species are believed to have a relatively high dispersal potential, such that both globally distributed and geographically isolated taxa exist. Primary occurrence data for three large, easily identified ciliate species, Parafavella gigantea, Schmidingerella serrata, and Zoothamnium pelagicum, and environmental data drawn from the National Oceanic and Atmospheric Administration's World Ocean Atlas were used to estimate each species’ spatial and environmental distributions using Maxent v3.3.3k. The predictive power of the models was tested with a series of spatial stratification studies, which were evaluated using partial receiver operating characteristic (ROC) statistics. Differences between niches occupied by each taxon were evaluated using background similarity tests. All predictions showed significant ability to anticipate test points. The null hypotheses of niche similarity were rejected in all background similarity tests comparing the niches among the three species. This article provides the first quantitative assessment of environmental conditions associated with three species of ciliates and a first estimate of their spatial distributions in the North Atlantic, which can serve as a benchmark against which to document distributional shifts. These species follow consistent, predictable patterns related to climate and environmental biochemistry; the importance of climatic conditions as regards protist distributions is noteworthy considering the effects of global climate change.
    • Endocrine correlates of reproductive status in breeding and nonbreeding wild female Moustached Tamarins

      Löttker, Petra; Huck, Maren; Heymann, Eckhard W.; Heistermann, Michael; Abteilung Soziobiologie, Deutsches Primatenzentrum, Göttingen, Germany; Institut für Neuro- und Verhaltensbiologie, Abteilung Verhaltensbiologie, Westfälische Wilhelms-Universität Münster, Germany; Lehrstuhl für Verhaltensforschung, Universität Bielefeld, Germany; Abteilung Reproduktionsbiologie, Deutsches Primatenzentrum Göttingen, Germany (2004-08)
      In callitrichid primates, reproduction is usually restricted to a single female per group. Reproductive rate is high and the occurrence of a postpartum estrus can lead to simultaneous lactation and pregnancy. In contrast, nonreproductive females often show ovarian inactivity. However, most studies on callitrichid reproductive physiology have been conducted in captivity, where conditions differ considerably from those in the wild, so that reproductive conditions may be strongly modified. Using fecal estrogen and progestogen measurements to monitor female reproductive status in 2 groups of wild moustached tamarins (Saguinus mystax), we examined 1) whether reproductive females in free-ranging groups also show postpartum estrus and 2) whether nonreproductive females demonstrate signs of ovarian activity. In both reproductive females, clear changes in the excretion pattern of progestogen and estrogen metabolites over time in combination with information on parturition dates allowed us to differentiate between pregnancy, a period of postpartum ovarian inactivity lasting for 54 and 64–82 days, and a period of ovarian activity before conception. Nonreproductive females demonstrated temporal fluctuations in hormone concentrations and absolute hormone levels that were similar to ones in the breeding females during the phase of ovarian activity. The results suggest that, in contrast to most captive female tamarins, reproductive females in wild groups of moustached tamarins do not have a postpartum estrus and that nonreproductive females show ovarian activity despite the presence of a breeding female.We therefore conclude that findings from captivity should be only carefully compared to the situation in the wild.
    • Enhancing online climate change education: distance and conventional university collaboration for a Master's curriculum

      Abbott, Dina; University of Derby (2012-05-29)
      This paper analyses the different ways in which both distance and conventional universities engage with learning and teaching. It argues that rather than seeing their roles as institutionally compartmentalised, there is much benefit in delivering online education through an institutional collaboration which develops synergies with a potential to contribute to citizen and professional practitioner empowerment, in this case, for debates about climate change. The example the paper draws on is that of a European Region Action Scheme for the Mobility of University Students (Erasmus) project ‘The Lived experience of climate change (LECH-e): interdisciplinary e-module development and virtual mobility’. The project brings together five distance and three conventional universities across six EU countries, plus the European Association of Distance Teaching Universities (EADTU), to create a Master’s curriculum in the area of climate change. It argues that universities across Europe have complementary strengths, both in terms of their disciplinary expertise and the ways in which they engage with students. Understanding the complex, real-world challenge of climate change requires a holistic approach which draws on these complementary strengths through collaborative work. Keywords: conventional universities; distance-learning universities; Master’s curriculum in climate change; collaboration.
    • Environment and extinction in the late Cenozoic of the North Atlantic area - insights from sclerochronology

      Johnson, Andrew L. A.; University of Derby (2017-10-12)
      Sclerochronology is the sister-field of dendrochronology, the study of tree rings. It involves analysis of the size and composition of increments within mineralised skeletons formed by accretion, such as those of bivalve molluscs, corals and coralline algae. Detailed information can be obtained on the age, growth-rate and environment of the organism concerned. In this talk I will show how sclerochronology is providing insights into Plio-Pleistocene changes in marine productivity and temperature in the North Atlantic region: their nature, cause and possible links to bivalve mass extinction during this interval (45% and 65% loss of species in the eastern and western Atlantic, respectively). This information may inform prediction of future extinction associated with global warming.
    • The escape behaviour of wild Greek tortoises Testudo graeca with and emphasis on geometrical shape discrimination

      Glavaschi, Alexandra; Beaumont, Ellen S.; University of Derby (Spanish Herpetological Society, 2015)
      Geometrical shape discrimination has been shown to play an important role in the spatial orientation of a wide variety of mammals and birds, while the study of this ability in particular and of cognitive processes in general has been rather neglected in reptiles. The present experiment aims to investigate the ability of wild Greek tortoises Testudo graeca from Topolog forest, Tulcea County, Romania, to discriminate between simple geometrical shapes. Forty-two adult tortoises were subjected to a task consisting of escaping from a square arena through one of the four available doors, each with a geometrical shape attached. Thirty-one individuals completed ten consecutive trials, requiring significantly less time for the last trial than for the first. This trend suggests that Greek tortoises developed and used an escape strategy, most likely relying on the geometrical shapes provided as cues. This experiment is the first to explore the cognitive processes of this species and further work should expand on the ecological significance of this ability.
    • Estimating food production in an urban landscape

      Grafius, Darren R.; Edmondson, Jill L.; Norton, Briony A.; Clark, Rachel; Mears, Meghann; Leake, Jonathan R.; Corstanje, Ron; Harris, Jim A.; Warren, Philip H.; University of Sheffield; et al. (Springer Science and Business Media LLC, 2020-03-20)
      There is increasing interest in urban food production for reasons of food security, environmental sustainability, social and health benefits. In developed nations urban food growing is largely informal and localised, in gardens, allotments and public spaces, but we know little about the magnitude of this production. Here we couple own-grown crop yield data with garden and allotment areal surveys and urban fruit tree occurrence to provide one of the first estimates for current and potential food production in a UK urban setting. Current production is estimated to be sufficient to supply the urban population with fruit and vegetables for about 30 days per year, while the most optimistic model results suggest that existing land cultivated for food could supply over half of the annual demand. Our findings provide a baseline for current production whilst highlighting the potential for change under the scaling up of cultivation on existing land.
    • An evaluation of Mesozoic rift-related magmatism on the margins of the Labrador Sea : implications for rifting and passive margin asymmetry.

      Phethean, Jordan; Peace, Alexander; McCaffrey, Ken; Imber, Jonathan; Nowell, Geoff; Gerdes, Keith; Dempsey, Edward; Durham University; Shell International (The Geological Society of America, 2016-09-29)
      The Labrador Sea is a small (~900 km wide) ocean basin separating southwest Greenland from Labrador, Canada. It opened following a series of rifting events that began as arly as the Late Triassic or Jurassic, culminating in a brief period of seafloor spreading commencing by polarity chron 27 (C27; Danian) and ending by C13 (Eocene-Oligocene oundary). Rift-related magmatism has been documented on both conjugate margins of the Labrador Sea. In southwest Greenland this magmatism formed a major coast-parallel dike swarm as well as other smaller dikes and intrusions. Evidence for rift-related magmatism on the conjugate Labrador margin is limited to igneous lithologies found in deep offshore exploration wells, mostly belonging to the Alexis Formation, along with a postulated Early Cretaceous nephelinite dike swarm (ca. 142 Ma) that crops out onshore, near Makkovik, Labrador. Our field observations of this Early Cretaceous nephelinite suite lead us to conclude that the early rift-related magmatism exposed around Makkovik is volumetrically and spatially limited compared to the contemporaneous magmatism on the conjugate southwest Greenland margin. This asymmetry in the spatial extent of the exposed onshore magmatism is consistent with other observations of asymmetry between the conjugate margins of the Labrador Sea, including the total sediment thickness in offshore basins, the crustal structure, and the bathymetric profile of the shelf width. We propose that the magmatic and structural asymmetry observed between these two conjugate margins is consistent with an early rifting phase dominated by simple shear rather than pure shear deformation. In such a setting Labrador would be the lower plate margin to the southwest Greenland upper plate.
    • Evidence for basement reactivation during the opening of the Labrador sea from the Makkovik province, Labrador, Canada: insights from field data and numerical models

      Peace, Alexander; Dempsey, Edward; Schiffer, Christian; Welford, J.; McCaffrey, Ken; Imber, Jonathan; Phethean, Jordan; Durham University; Memorial University of Newfoundland, Canada; University of Hull; et al. (MDPI AG, 2018-08-20)
      The onshore exposures adjacent to modern, offshore passive continental margins may preserve evidence of deformation from the pre-, syn-, and post-rift phases of continental breakup that allow us to investigate the processes associated with and controlling rifting and breakup. Here, we characterize onshore brittle deformation and pre-rift basement metamorphic mineral fabric from onshore Labrador in Eastern Canada in the Palaeoproterozoic Aillik Domain of the Makkovik Province. Stress inversion (1) was applied to these data and then compared to (2) numerical models of hybrid slip and dilation tendency, (3) independent calculations of the regional geopotential stress field, and (4) analyses of palaeo-stress in proximal regions from previous work. The stress inversion shows well-constrained extensional deformation perpendicular to the passive margin, likely related to pre-breakup rifting in the proto-Labrador Sea. Hybrid slip and dilatation analysis indicates that inherited basement structures were likely oriented in a favorable orientation to be reactivated during rifting. Reconstructed geopotential stresses illuminate changes of the ambient stress field over time and confirm the present paleo-stress estimates. The new results and numerical models provide a consistent picture of the late Mesozoic-Cenozoic lithospheric stress field evolution in the Labrador Sea region. The proto-Labrador Sea region was characterized by a persistent E–W (coast-perpendicular) extensional stress regime, which we interpret as the pre-breakup continental rifting that finally led to continental breakup. Later, the ridge push of the Labrador Sea spreading ridge maintained this general direction of extension. We see indications for anti-clockwise rotation of the direction of extension along some of the passive margins. However, extreme persistent N–S-oriented extension as indicated by studies further north in West Greenland cannot be confirmed.
    • Evidence for melting mud in Earth’s mantle from extreme oxygen isotope signatures in zircon.

      Spencer, Christopher J.; Cavosie, Aaron J.; Raub, Timothy D.; Rollinson, Hugh; Jeon, Heejin; Searle, Michael P.; Miller, Jodie A.; McDonald, Bradley J.; Evans, Noreen J.; Curtin University; et al. (Geological Society of America, 2017-10-02)
      Melting of subducted sediment remains controversial, as direct observation of sediment melt generation at mantle depths is not possible. Geochemical fingerprints provide indirect evidence for subduction delivery of sediment to the mantle; however, sediment abundance in mantle-derived melt is generally low (0%–2%), and difficult to detect. Here we provide evidence for melting of subducted sediment in granite sampled from an exhumed mantle section. Peraluminous granite dikes that intrude peridotite in the Oman–United Arab Emirates ophiolite have U-Pb ages of 99.8 ± 3.3 Ma that predate obduction. The dikes have unusually high oxygen isotope (δ18O) values for whole rock (14–23‰) and quartz (20–22‰), and yield the highest δ18O zircon values known (14–28‰; values relative to Vienna standard mean ocean water [VSMOW]). The extremely high oxygen isotope ratios uniquely identify the melt source as high-δ18O marine sediment (pelitic and/or siliciceous mud), as no other source could produce granite with such anomalously high δ18O. Formation of high-δ18O sediment-derived (S-type) granite within peridotite requires subduction of sediment to the mantle, where it melted and intruded overlying mantle wedge. The granite suite described here contains the highest oxygen isotope ratios reported for igneous rocks, yet intruded mantle peridotite below the Mohorovičić seismic discontinuity, the most primitive oxygen isotope reservoir in the silicate Earth. Identifying the presence and quantifying the extent of sediment melting within the mantle has important implications for understanding subduction recycling of supracrustal material and effects on mantle heterogeneity over time.
    • Evidence for rapid, tide-related shifts in the microbiome of the coral Coelastrea aspera

      Sweet, Michael J.; Brown, Barbara E.; Dunne, Richard P.; Singleton, Ian; Bulling, Mark T.; University of Derby; Newcastle University; North Highland College; Edinburgh Napier University (Springer, 2017-03-23)
      Shifts in the microbiome of the intertidal coral Coelastrea aspera (formally known as Goniastrea aspera) from Phuket, Thailand, were noted over the course of a 4-d period of spring tides. During this time, corals were naturally exposed to high temperatures, intense solar radiation, sub-aerial exposure and tidally induced water fluxes. Analysis of the 16S microbiome highlighted that the corals harbored both ‘core or stable’ communities and those which appeared to be more ‘transient or sporadic.’ Only relatively few microbial associates were classified as core microbes; the majority were transient or sporadic. Such transient associates were likely to have been governed by tidally induced variations in mucus thickness and water fluxes. Here we report strong shifts in the bacterial community of C. aspera over a short temporal scale. However, we also show significant differences in the timing of shifts between the two age groups of corals studied. More rapid changes (within 2 d of sub-aerial exposure) occurred within the 4-yr-old colonies, but a slightly delayed response was observed in the 10-yr-old colonies, whereby the microbial associates only changed after 4 d. We hypothesize that these shifts are age related and could be influenced by the observed baseline differences in the microbiome of the 4- and 10-yr-old corals, bacteria–bacteria interactions, and/or host energetics.
    • Evidence, cause and consequence of exceptionally rapid growth in Pliocene scallops of the US eastern seaboard

      Johnson, Andrew L. A.; Valentine, Annemarie; Leng, Melanie J.; Sloane, Hilary J.; Schoene, Bernd; Surge, Donna; University of Derby (4th International Sclerochronology Conference, 2016-06)
      Scallops are amongst the fastest growing of bivalves, with many species growing in the order of 40 mm per annum in early ontogeny, and reliable evidence of early ontogenetic growth-rates up to 70 mm per annum in wild populations of certain species. From the evidence of oxygen isotope (δ18O) sclerochronology, modern examples of the western Atlantic genus Placopecten grow about 40 mm per annum in early ontogeny. The same approach reveals similar growth rates in Pliocene examples from Virginia and North Carolina. By contrast Pliocene examples of the extinct genera Chesapecten and Carolinapecten from Virginia grew at least 75 mm per annum, faster than has been recorded in any wild modern scallop, and examples of Carolinapecten from Florida grew up to 140 mm per annum, twice the maximum rate in wild modern scallops. The rapid overall growth of Carolinapecten is matched by exceptionally large microgrowth increments. In specimens with the fastest overall growth the number of increments approximately equals the number of days indicated by the oxygen isotopic data (e.g. c. 180 over half an oxygen isotope cycle), implying that deposition was daily. Specimens with slower overall growth do not have smaller increments but have substantially fewer than the number of days indicated by δ18O evidence, showing that reduced overall growth was a consequence of periodic interruptions rather than permanently less favourable conditions. Since few individuals lived more than a year, rapid somatic growth must have been accompanied by gamete production, implying abundant food resources. Intervals of particularly rapid growth (largest microgrowth increments) are fairly closely correlated with increases in δ13C, as might have been caused by phytoplankton blooms. However, there is little evidence that these were stimulated by upwelling since there are few indications of a matching increase in δ18O (i.e. colder water). Instead, primary productivity may have been enhanced by nutrient supply from the land. Whatever the cause of high primary productivity in the Pliocene of the US eastern seaboard, the subsequent demise of two scallop genera with exceptionally rapid growth seems as likely to relate to a decline in productivity as to a fall in temperature.
    • Evolution of high-Arctic glacial landforms during deglaciation.

      Midgley, Nicholas G.; Tonkin, Toby N.; Graham, David, J.; Cook, Simon J.; Nottingham Trent University; University of Derby; Loughborough University; University of Dundee (Elsevier, 2018-03-29)
      Glacial landsystems in the high-Arctic have been reported to undergo geomorphological transformation during deglaciation. This research evaluates moraine evolution over a decadal timescale at Midtre Lovénbreen, Svalbard. This work is of interest because glacial landforms developed in Svalbard have been used as an analogue for landforms developed during Pleistocene mid-latitude glaciation. Ground penetrating radar was used to investigate the subsurface characteristics of moraines. To determine surface change, a LiDAR topographic data set (obtained 2003) and a UAV-derived (obtained 2014) digital surface model processed using structure-from-motion (SfM) are also compared. Evaluation of these data sets together enables subsurface character and landform response to climatic amelioration to be linked. Ground penetrating radar evidence shows that the moraine substrate at Midtre Lovénbreen includes ice-rich (radar velocities of 0.17 m ns−1) and debris-rich (radar velocities of 0.1–0.13 m ns−1) zones. The ice-rich zones are demonstrated to exhibit relatively high rates of surface change (mean thresholded rate of −4.39 m over the 11-year observation period). However, the debris-rich zones show a relatively low rate of surface change (mean thresholded rate of −0.98 m over the 11-year observation period), and the morphology of the debris-rich landforms appear stable over the observation period. A complex response of proglacial landforms to climatic warming is shown to occur within and between glacier forelands as indicated by spatially variable surface lowering rates. Landform response is controlled by the ice-debris balance of the moraine substrate, along with the topographic context (such as the influence of meltwater). Site-specific characteristics such as surface debris thickness and glaciofluvial drainage are, therefore, argued to be a highly important control on surface evolution in ice-cored terrain, resulting in a diverse response of high-Arctic glacial landsystems to climatic amelioration. These results highlight that care is needed when assessing the long-term preservation potential of contemporary landforms at high-Arctic glaciers. A better understanding of ice-cored terrain facilitates the development of appropriate age and climatic interpretations that can be obtained from palaeo ice-marginal landsystems.