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115. Which features of UK farmland are important in retaining territories of the rapidly declining Turtle Dove Streptopelia turtur ?

Author

Dunn, Jenny C. and Morris, Antony J.

Abstract

Capsule Turtle Doves continue to show a strong population decline; territories were more likely to be retained in areas with more nesting habitat, and more suitable foraging habitat. Aim To determine which features of farmland in England are important for retaining Turtle Dove territories Methods Fifty-eight grid squares with recent records of territorial Turtle Doves were resurveyed, and squares retaining Turtle Dove territories compared with those from which Turtle Doves had been lost. Results Turtle Dove territories were detected in 48% of squares resurveyed. When correcting for the 70% detection rate of the survey methodology, territories were present in 66% of squares surveyed suggesting a 34% decline over a 2-year period. Established scrub and hedgerows > 4 m tall positively influenced Turtle Dove presence and abundance, as did standing water. Bare ground and fallow had positive effects on Turtle Dove abundance whereas grazed land negatively impacted abundance. Conclusion The positive effects of area of established scrub and volume of large hedgerows are likely to represent a declining density of birds selecting the best quality nest sites. We suggest instead that foraging habitat may be limiting distribution. [ABSTRACT FROM AUTHOR]

Published
2012
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117. Chaffinch Fringilla coelebs foraging patterns, nestling survival and territory distribution on lowland farmland.

Author

Whittingham, Mark J., Bradbury, Richard B., Wilson, Jeremy D., Morris, Antony J., Perkins, Allan J., and Siriwardena, Gavin M.

Abstract

Numbers of many bird species which breed on farmland, and are reliant on cropped land for feeding or nesting, declined between the 1960s and 1990s. In contrast, Chaffinch Fringilla coelebs numbers increased on farmland over the same period. This study investigates the influence of both cropped and noncropped land on Chaffinches foraging for nestlings, nestling survival and territory density. The study was carried out on nine mixed lowland farms in south central England in 1996 and 1997. Chaffinches made little use of cropped areas when foraging for young (less than 9% of foraging visits, despite cropped areas covering 93% of study areas). Instead, trees and bushes influenced foraging patterns and breeding success. Extensive use was made of trees and bushes by adults searching for food for nestlings (75% of foraging visits were to hedges and trees within boundaries or fields, despite these areas covering <3% of study areas). Oaks (69% of visits) and Willows (15% of visits) were found to be the most favoured species of tree for foraging. In one year of the study, chick starvation was less frequent in nests located on field boundaries with Oak trees than in nests on boundaries without Oaks. Successful nests also tended to be closer to Oak or Willow trees than those where nestlings starved. Territory density was not related to hedgerow structure, presence or absence of Oaks and Willows in field boundaries, or adjacent cropping. Our findings on nest survival were supported by analysis of British Trust for Ornithology nest record data which revealed that nests associated with trees had better brood survival rates than sites not located close to trees. The use of trees and shrubs for feeding and nesting in the farming landscape and the ability to utilize unkempt hedgerows may have contributed to the ability of Chaffinches to persist on farmland despite wide-scale agricultural change in recent decades. [ABSTRACT FROM AUTHOR]

Published
2001
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118. Habitat associations and breeding success of yellowhammers on lowland farmland.

Author

Bradbury, Richard B., Kyrkos, Antonios, Morris, Antony J., Clark, Stéphanie C., Perkins, Allan J., and Wilson, Jeremy D.

Subjects
EMBERIZA citrinella, HABITAT selection, ANIMAL sexual behavior, BIRD behavior
Abstract

1. Yellowhammers began to decline on British lowland farmland in the late 1980s and losses are presently 10% per year. This study examined variation in the habitat selection and breeding success of yellowhammers, allowing an evaluation of whether Britain's yellowhammer decline might have been caused by recent changes in agriculture. 2. Yellowhammer territories were associated with hedgerows, vegetated ditches and wide uncultivated grassy margins around fields. Pasture and silage leys were avoided. Nests were built among herbaceous vegetation in ditches or in the shrubby vegetation of hedgerows. 3. Breeding started slightly earlier on organic farms than on intensively managed farms, but no measure of breeding success differed between farm types. Predation was the cause of most (64%) nest failures. A maximum of three breeding attempts (two successful) was observed per pair, with a mean clutch size of 3·3, a Mayfield nest success rate of 0·46, and 2·6 nestlings fledged per successful brood. These data, together with published estimates of adult yellowhammer survival and of post-fledging survival among other passerines, suggest that breeding productivity is too low to maintain a stable population. 4. The removal of hedgerows or abandonment of hedge management, filling or clearing of ditches, intensification of grassland management and cropping or grazing right up to the field edge, are all likely to have adversely affected yellowhammers on lowland farmland in southern England. Policy reforms that redirect subsidy support to environmentally beneficial management of field margin habitats and retention of winter-feeding sites such as stubbles should assist in restoring populations of breeding yellowhammers on lowland farmland. 5. Our data expand further the array of farmland bird species for which interactions between agricultural change and population change are increasingly understood. [ABSTRACT FROM AUTHOR]

Published
2000
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121. TA skills.

Author

Morris, Antony

Published
2021

122. The decline of the Turtle Dove: dietary associations with body condition and competition with other columbids analysed using high throughput sequencing

Author

Dunn, Jenny, Stockdale, Jennifer E., Moorhouse-Gann, Rosemary J., McCubbin, Alexandra, Hipperson, Helen, Morris, Antony J., Grice, Philip V., Symondson, William O. C., Dunn, Jenny, Stockdale, Jennifer E., Moorhouse-Gann, Rosemary J., McCubbin, Alexandra, Hipperson, Helen, Morris, Antony J., Grice, Philip V., and Symondson, William O. C.

Abstract

Dietary changes linked to the availability of anthropogenic food resources can have complex implications for species and ecosystems, especially when species are in decline. Here, we use recently developed primers targeting the ITS2 region of plants to characterise diet from faecal samples of four UK columbids, with particular focus on the European turtle dove (Streptopelia turtur), a rapidly declining obligate granivore. We examine dietary overlap between species (potential competition), associations with body condition in turtle doves, and spatiotemporal variation in diet. We identified 143 taxonomic units, of which we classified 55% to species, another 34% to genus and the remaining 11% to family. We found significant dietary overlap between all columbid species, with the highest between turtle doves and stock doves (Columba oenas), then between turtle doves and woodpigeons (Columba palumbus). The lowest overlap was between woodpigeons and collared doves (Streptopelia decaocto). We show considerable change in columbid diets compared to previous studies, probably reflecting opportunistic foraging behaviour by columbids within a highly anthropogenically-modified landscape, although our data for non-turtle doves should be considered preliminary. Nestling turtle doves in better condition had a higher dietary proportion of taxonomic units from natural arable plant species, and a lower proportion of taxonomic units from anthropogenic food resources such as garden bird seed mixes and brassicas. This suggests that breeding ground conservation strategies for turtle doves should include provision of anthropogenic seeds for adults early in the breeding season, coupled with habitat rich in accessible seeds from arable plants once chicks have hatched.

123. Post-fledging habitat selection in a rapidly declining farmland bird, the European turtle dove Streptopelia turtur

Author

Dunn, Jenny C., Morris, Antony J., Grice, Philip V., Dunn, Jenny C., Morris, Antony J., and Grice, Philip V.

Abstract

Post-fledging survival plays a vital role in the dynamics of bird populations and yet is the least studied avian life-stage. Habitat requirements post-fledging may have important implications for behaviour and survival, especially for declining populations in landscapes that have undergone wide-scale anthropogenic modification, resulting in an altered distribution and composition of habitats. The European Turtle Dove is a widespread but rapidly declining species both within the UK and across Europe. Reduced seed food availability is thought to influence breeding success of this species, but it is not known whether post-fledging survival may also be influenced by seed availability. Here, we use leg-ring radio-tag attachments to monitor post-fledging survival and movements in 15 Turtle Dove nestlings from eight nests monitored during 2014 as part of a wider autecological study. Fledglings remained in close proximity to their nest for three weeks post-tagging, spending more than half their time in the immediate vicinity (within ∼ 20 m) of the nest. 95% of foraging trips during this period were within 329 m of the nest and fledglings selected seed-rich habitat (semi-natural grassland, low-intensity grazing, fallow and quarries). Fledglings that were heavier and in better body condition at seven days old were more likely to survive for 30 days post-fledging, and the proportion of available seed-rich habitat was a strong predictor of nestling weight and condition at seven days old. Whilst our sample size is modest, this study highlights the crucial role of food availability in juvenile survival, both while adults are feeding nestlings, and to recently fledged young, and the potential for agri-environment schemes providing foraging and nesting habitats in close proximity to provide important benefits.

124. High rates of infection by blood parasites during the nestling phase in UK Columbids with notes on ecological associations

Author

Dunn, Jenny C., Stockdale, Jennifer E., Bradford, Emma L., McCubbin, Alexandra, Morris, Antony J., Grice, Philip V., Goodman, Simon J., Hamer, Keith C., Dunn, Jenny C., Stockdale, Jennifer E., Bradford, Emma L., McCubbin, Alexandra, Morris, Antony J., Grice, Philip V., Goodman, Simon J., and Hamer, Keith C.

Abstract

Studies of blood parasite infection in nestling birds rarely find a high prevalence of infection. This is likely due to a combination of short nestling periods (limiting the age at which nestlings can be sampled) and long parasite prepatent periods before gametocytes can be detected in peripheral blood. Here we examine rates of blood parasite infection in nestlings from three Columbid species in the UK. We use this system to address two key hypotheses in the epidemiology of avian haemoparasites: first, that nestlings in open nests have a higher prevalence of infection; and second, that nestlings sampled at 14 days old have a higher apparent infection rate than those sampled at 7 days old. Open-nesting individuals had a 54% infection rate compared with 25% for box-nesters, probably due to an increased exposure of open-nesting species to dipteran vectors. Nestlings sampled at 14 days had a 68% infection rate compared with 32% in nestlings sampled at 7 days, suggesting that rates of infection in the nest are high. Further work should examine nestlings post-fledging to identify rates of successful parasite infection (as opposed to abortive development within a dead-end host) as well as impacts on host post-fledging survival and behaviour

125. Multi-taxa benefits of a targeted single-species agri-environment option

Author

Dunn, Jenny, Hartwell, Vivien, Morris, Antony, Dunn, Jenny, Hartwell, Vivien, and Morris, Antony

Abstract

Agri-environment schemes such as the Environmental Stewardship in England provide a range of options, including some targeted at single species, which may benefit a wide range of other species or taxa. To ascertain whether trials of an agri-environment measure designed for a single species had wider biodiversity benefits, we describe monitoring of pollinators (bumblebees and butterflies) on plots of a novel seed mix aimed at providing a source of seed food throughout the breeding season for the rapidly declining European Turtle Dove Streptopelia turtur. We compare pollinator abundance on these turtle dove plots to that on six control habitat types: fallow, grass margins, meadow, nectar flower mixture, wild bird cover and floristically enhanced margins. The abundance of foraging bumblebees and butterflies was higher on turtle dove plots than in fallow and wild bird cover habitats. Surprisingly, foraging bumblebee abundance was higher, and foraging butterfly abundance marginally higher on turtle dove plots than on nectar flower mixture. Whilst the specific mix described here is to be altered to increase access to foraging turtle doves, we suggest that the modified mix, to be rolled out through Higher Level Stewardship, is also likely to provide valuable resources for pollinators, adding to the growing body of literature demonstrating multi-taxa benefits of agri-environment options designed to benefit one species.

126. Testing bespoke management of foraging habitat for European turtle doves Streptopelia turtur

Author

Dunn, Jenny C., Morris, Antony J., Grice, Philip V., Dunn, Jenny C., Morris, Antony J., and Grice, Philip V.

Abstract

Agri-environment schemes (AES) are increasingly being employed to mitigate biodiversity loss in agricultural environments. The European Turtle Dove Streptopelia turtur is an obligate granivorous bird in rapid decline within both the UK (−96% since 1970) and across continental Europe (−77% since 1980), despite widespread uptake of AES. Here, we assess the efficacy of a potentially new, sown agri-environment option designed to provide abundant, accessible seed for S. turtur during the breeding season. During summer 2011 we compared vegetation structure and seed provision on trial plots to control habitat types (existing agri-environment options thought to potentially provide S. turtur foraging habitat) to assess whether trial plots performed better for foraging S. turtur than control habitats. In September 2011 all trial plots were topped (cut) and half of a subset of trial plots were then scarified (60% of soil surface disturbed). Vegetation structure on topped, and topped and scarified trial plots was measured during summer 2012 to determine which management regime was most effective in maintaining suitable sward structure and seed provision into the second year. No control habitat type produced as much seed important in S. turtur diet as trial plots at any point during year one. Trial plots provided accessible vegetation structure early in the season with no difference in vegetation metrics between trial plots and previously published data on S. turtur foraging locations. However, to allow later access, management is required during mid-June to open up the sward through localized topping or scarification. Vegetation structure during year two was generally too dense to attract foraging S. turtur. However, scarifying trial plots during the September following sowing encouraged self-seeding of Fumaria officinalis (a plant species historically forming a significant proportion of S. turtur diet during the breeding season) into the second year, with this species present

127. Which features of UK farmland are important in retaining territories of the rapidly declining Turtle Dove Streptopelia turtur?

Author

Dunn, Jenny C., Morris, Antony J., Dunn, Jenny C., and Morris, Antony J.

Abstract

Capsule Turtle Doves continue to show a strong population decline; territories were more likely to be retained in areas with more nesting habitat, and more suitable foraging habitat. Aim To determine which features of farmland in England are important for retaining Turtle Dove territories Methods Fifty-eight grid squares with recent records of territorial Turtle Doves were resurveyed, and squares retaining Turtle Dove territories compared with those from which Turtle Doves had been lost. Results Turtle Dove territories were detected in 48% of squares resurveyed. When correcting for the 70% detection rate of the survey methodology, territories were present in 66% of squares surveyed suggesting a 34% decline over a 2-year period. Established scrub and hedgerows > 4 m tall positively influenced Turtle Dove presence and abundance, as did standing water. Bare ground and fallow had positive effects on Turtle Dove abundance whereas grazed land negatively impacted abundance. Conclusion The positive effects of area of established scrub and volume of large hedgerows are likely to represent a declining density of birds selecting the best quality nest sites. We suggest instead that foraging habitat may be limiting distribution.

128. Non-cultured faecal and gastrointestinal seed samples fail to detect Trichomonad infection in clinically and sub-clinically infected columbid birds

Author

Dunn, Jenny C., Stockdale, Jennifer E., McCubbin, Alexandra, Thomas, Rebecca C., Goodman, Simon J., Grice, Philip V., Morris, Antony J., Hamer, Keith C., Symondson, William O. C., Dunn, Jenny C., Stockdale, Jennifer E., McCubbin, Alexandra, Thomas, Rebecca C., Goodman, Simon J., Grice, Philip V., Morris, Antony J., Hamer, Keith C., and Symondson, William O. C.

Abstract

Trichomonosis, caused by the protozoan Trichomonas gallinae, is an emerging infectious disease in finches, and is more commonly found in columbids and raptors. Infections can be sub-clinical or cause morbidity and mortality, but the parasite is currently only detectable by incubation of an oral swab. Here, we test whether T. gallinae parasites can be detected by PCR from faecal or non-cultured samples from the oral cavity and gastrointestinal tract of infected Turtle Doves (Streptopelia turtur). PCR did not detect T. gallinae parasites in any faecal samples screened, and in only 1 of 11 oral/gastrointestinal samples (from the mouth of a nestling suspected to have died from trichomonosis). We conclude that both oral swabs and parasite culture are still necessary to detect the sub-clinical presence of T. gallinae infection in birds.

129. Trichomonad parasite infection in four species of Columbidae in the UK

Author

Lennon, Rosie J., Dunn, Jenny C., Stockdale, Jennifer E., Goodman, Simon J., Morris, Antony J., Hamer, Keith C., Lennon, Rosie J., Dunn, Jenny C., Stockdale, Jennifer E., Goodman, Simon J., Morris, Antony J., and Hamer, Keith C.

Abstract

Trichomonas gallinae is an emerging pathogen in wild birds, linked to recent declines in finch (Fringillidae) populations across Europe. Globally, the main hosts for this parasite are species of Columbidae (doves and pigeons); here we carry out the first investigation into the presence and incidence of Trichomonas in four species of Columbidae in the UK, through live sampling of wild-caught birds and subsequent PCR. We report the first knownUKcases of Trichomonas infection in 86% of European Turtle Doves Streptopelia turtur sampled, along with 86% of Eurasian Collared Doves Streptopelia decaocto, 47% of Woodpigeons Columba palumbus and 40% of Stock Doves Columba oenas. Birds were more likely to be infected if the farm provided supplementary food for gamebirds. We found three strains of T. gallinae and one strain clustering within the Trichomonas tenax clade, not previously associated with avian hosts in the UK. One T. gallinae strain was identical at the ITS/5.8S/ITS2 ribosomal region to that responsible for the finch trichomonosis epizootic. We highlight the importance of increasing our knowledge of the diversity and ecological implications of Trichomonas parasites in order further to understand the sub-clinical impacts of parasite infection.

131. Beyond the standard tilt correction: analysing the paleomagnetism of metamorphic soles.

Author

Çavdar, Buğra, Morris, Antony, Anderson, Mark, Menegon, Luca, and Parlak, Osman

Subjects
*PALEOMAGNETISM, *MAGNETIC declination, *FLATFISHES, *METAMORPHIC rocks, *AMPHIBOLITES, *GARNET, *REMANENCE, *ROTATIONAL motion
Abstract

Structural corrections are an essential part of any paleomagnetic study and are applied by restoring sampled units to a paleohorizontal reference frame via rotation around the line of strike. But how may paleomagnetic data be interpreted in cases where we do not know the attitude of the sampled rocks at the time of remanence acquisition? This is a scenario encountered when attempting to use magnetizations to determine the tectonic evolution of the metamorphic soles of ophiolites. These may experience significant rotation during their exhumation from peak metamorphic depths and their subsequent emplacement. For example, a recent metamorphic sole exhumation model (van Hinsbergen et al., 2015, doi: 10.1002/2015GC005745) involves flattening of a subducting slab during forearc spreading, implying significant rotation of sole rocks after formation. Here we test this exhumation mechanism using data from the Mersin ophiolite (Tauride Belt, southern Turkey), a well-exposed Neotethyan suprasubduction zone ophiolite that formed in the Late Cretaceous. The Mersin metamorphic sole rocks (predominantly amphibolites) are inferred to have formed at the top of the down-going plate during subduction. Previous paleomagnetic analysis of non-metamorphosed dykes cutting the sole rocks indicate a 45° clockwise rotation of the sole and dykes after intrusion around a NE-trending, shallowly plunging, ridge-parallel axis (Morris et al., 2017, 10.1016/j.epsl.2017.08.040). Here we show that the host amphibolites carry a statistically different magnetization to that of the dykes they host, providing evidence for an earlier phase of rotation. Tectonic interpretation of these data in the absence of paleohorizontal markers cannot be achieved using standard paleomagnetic tilt corrections. Instead we adopt a Monte Carlo approach to modelling potential net tectonic rotation parameters and permissible orientations of the foliation in the sole rocks at the time of magnetization and incorporating statistical uncertainties into the analysis, after back-stripping the later rotation of the sole-hosted dykes. Results suggest that the sole acquired its remanence while the metamorphic foliation dipped moderately to the ENE and then underwent an early phase of anticlockwise rotation around an inclined, NW plunging axis. This is consistent with a two-stage rotation model involving an earlier phase of exhumation by slab flattening followed by a later spreading-related rotation around a ridge-parallel axis after accretion of the sole to the base of the ophiolite. These rotations around different inclined axes are consistent with a geodynamic setting similar to the modern Andaman Sea, where spreading in a suprasubduction zone environment occurs obliquely to the subduction direction of the down-going plate. [ABSTRACT FROM AUTHOR]

Published
2019

136. Reversing declines in farmland birds: How much agri‐environment provision is needed at farm and landscape scales?

Author

Sharps, Elwyn, Hawkes, Robert W., Bladon, Andrew J., Buckingham, David L., Border, Jennifer, Morris, Antony J., Grice, Philip V., and Peach, Will J.

Subjects
*BIRD populations, *BIRD declines, *WILDLIFE conservation, *LANDSCAPES, *ENVIRONMENTAL management, *FARMS
Abstract

Agri‐environment schemes (AES) are the primary policy mechanism for addressing farmland biodiversity declines across Europe. Despite previous studies on the impacts of AES on biodiversity, there is little empirical evidence on the scale of provision required to reverse declines.Across three regions of lowland England with contrasting farm systems (arable, pastoral, mixed), we estimated avian population growth rates (PGRs) on farmland with high AES provision ('higher‐tier': average bird‐friendly option cover = 7.4%), low AES provision ('lower‐tier': 2.3%) and no bird‐friendly AES ('no AES'). Ten‐year PGRs were derived for 24 species and three multi‐species groups comprising farmland‐associated species ('farmland birds'), species of conservation concern ('priority birds') and species restricted to farmland ('specialist birds'). We used PGRs to simulate the proportion of the regional farmland landscape that would have to be assigned to higher‐ and lower‐tier agreements to stabilise or increase populations.In the arable and pastoral regions, 13/23 and 13/22 species, respectively, had more positive PGRs under higher‐tier AES than on no AES farmland (none had more negative PGRs), compared to 4/22 (positive) and 1/22 (negative) in the mixed region. Only two to four species per region exhibited more positive PGRs under lower‐tier AES compared to no AES farmland.Multi‐species PGRs in the arable and pastoral regions increased from no AES (strong decline), to lower‐tier (decline or stability) to higher‐tier (moderate or strong increase). There was no overall AES effect in the mixed region.To increase regional farmland bird populations by 10% over 10 years, 47% and 26% of the farmed landscape would need to be devoted to higher‐tier agreements in arable and pastoral landscapes respectively. This falls to 34% and 17% when higher‐tier is targeted at localities supporting higher abundances of target species, and to 29% and 10% when 30% of the farmed landscape is also devoted to lower‐tier. Priority and specialist birds require higher provision levels.Policy implications. Where farmland bird recovery is an AES objective, farms should prioritise higher‐tier agreement delivery over lower‐tier. Farmland bird responses to AES provision are likely to vary regionally, but careful targeting will reduce the amount needed in the landscape. [ABSTRACT FROM AUTHOR]

Published
2023
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138. Dear editor.

Author

Frost, Charles, Cherry, Evelyn, Burns, John, LaMoreaux, Phil, Morris, Antony, and Henderson, Walter

Subjects
LETTERS to the editor, GEOLOGY, EARTH (Planet), NATURAL bridges
Abstract

Presents letters to the editor referencing articles and topics discussed in previous issues. "Earth's Exotic Geology," which discussed the jointing of the bedded sandstone; Information on the Tonto Natural Bridge in Arizona.

Published
2005

139. Integrated geophysical, geochemical and structural analysis of the Mersin ophiolite, southern Turkey

Author

Omer, Ahmed Fatih and Morris, Antony

Subjects
552, ophiolite, mersin, palaeomagnetism, suprasubduction
Abstract

This study examines the tectonic evolution of the Mersin ophiolite of the central Tauride of Turkey, using palaeomagnetic, structural and geochemical analyses. This ophiolite represents one of the best examples of Tethyan-type ophiolites formed by supra-subduction zone spreading within the northern Neotethyan Ocean basin during the Late Cretaceous. It exposes a 3.0 km section of lower crustal, cumulate rocks, and tectonically separated exposures of the underlying mantle sequence and metamorphic sole, both of which are cut by basaltic dykes. Stepwise thermal and alternating field demagnetization of ultramafic and gabbroic cumulates from 18 sites mostly identified single components of remanent magnetization characterized by ENE-directed, moderately upwards inclined directions in geographic coordinates with high coercivities/high unblocking temperatures. The slight increase in scattering in remanence directions after tilt correction has been interpreted to be related to local variations in orientation of cumulates layering within the magma chamber. Rock magnetic investigations showed that magnetite is the main magnetic mineral in the majority of ultramafic, gabbro and dyke rock samples, and rock magnetic and demagnetization characteristics suggest that the samples carry thermoremanent magnetizations acquired during crustal accretion. Net tectonic rotation analyses show that all the units of the Mersin ophiolite, including lower crustal cumulates, dykes in the mantle sequence and dykes in the metamorphic sole have experienced large clockwise rotations around NE- trending, moderately plunging to sub-horizontal axes. Correcting anisotropy of magnetic susceptibility data for the effects of these rotations suggests that magmatic flow in the cumulates had an initial NNE-SSW orientation, which if assumed to relate to seafloor spreading suggests that the Mersin spreading axis was oriented WNW-ESE. This is consistent with regional palaeogeographic reconstructions. The net tectonic rotation data show that dykes in the metamorphic sole are rotated by c. 45°, significantly less than the c. 115° rotations seen in the mantle sequence and in the cumulate sequences of the overlying thrust sheets. These results therefore document an initial stage of intra-oceanic clockwise rotation of the ophiolite that occurred after initial detachment but prior to emplacement of dykes cutting the metamorphic sole. Subsequent additional clockwise rotation (of all units) may be attributed to further intra-oceanic rotation (preferred interpretation) or to later emplacement of the ophiolite onto the Tauride continental margin. Finally, some new, preliminary data are presented from the Lizard ophiolite of Cornwall in Appendix A, forming the results of a training project undertaken while awaiting permission for fieldwork in Turkey.

Published
2014

140. Have Welsh agri‐environment schemes delivered for focal species? Results from a comprehensive monitoring programme.

Author

MacDonald, Michael A., Angell, Ruth, Dines, Trevor D., Dodd, Stephen, Haysom, Karen A., Hobson, Russel, Johnstone, Ian G., Matthews, Vaughn, Morris, Antony J., Parry, Rob, Shellswell, Catharine H., Skates, James, Tordoff, George M., Wilberforce, Elizabeth M., and Manning, Peter

Subjects
*ENVIRONMENTAL protection, *HABITATS, *WILDLIFE conservation, *SPECIES diversity, WELSH politics & government
Abstract

Agri‐environment schemes (AES) have been criticized for being inadequately monitored and for not delivering the expected benefits to nature. Consequently, the Welsh Government funded a comprehensive programme of monitoring of AES between 2009 and 2012. The AES assessment focused on Tir Gofal (which translates as "Land in Care") but also included the Organic Farming Scheme, and monitoring focused on a range of taxa of conservation importance: arable plants, grassland fungi, bats (six species), butterflies (three species), birds (five species), water vole and brown hare.Field surveys were carried out on matched farms and fields within and outside of AES. Response variables were spatial trends of abundance, occurrence and species richness, and were modelled against AES status. Existing data were also available for two bird species.Few differences were observed between AES and non‐AES farms and fields. Those that were observed were for species that use arable habitats (which are uncommon in Wales): arable plants, yellowhammers and brown hares. The lack of differences in non‐arable habitats may reflect the smaller contrast between AES and non‐AES management in these habitats. It may also reflect the original condition of habitat entered into AES prescriptions, as most non‐arable prescriptions were defined by mandatory management of existing habitats, rather than optional habitat creation or restoration, which is the case for most arable prescriptions.Despite the lack of differences observed, AES may help to maintain populations of species, making it more likely that they will persist in the landscape. There is evidence, from this monitoring programme and elsewhere, that AES can increase the populations of species, when well targeted and implemented.Policy implications. Our results indicate that Welsh Agri‐environment schemes (AES) have been only partly successful in achieving their stated aim of "maintaining and enhancing species abundance". They can be used to improve AES design and management, both in Wales and more widely, by identifying and promoting effective management interventions, and by identifying ineffective management interventions and seeking alternatives. Comprehensive monitoring of AES, combined with specific targets regarding expected outcomes, is essential to determine whether AES are providing value for money. [ABSTRACT FROM AUTHOR]

Published
2019
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141. GEOPHYSICAL MODELLING OF MAGNETIC ANOMALIES OVER THE BALLANTRAE OPHIOLITE COMPLEX AND SOUTHERN UPLANDS FAULT SYSTEM, SW SCOTLAND

Author

Can, Arzum Cansu, Morris, Antony, and Faculty of Science and Engineering

Subjects
Ballantrae, ophiolite, magnetic anomalies, ResM, geophysical modelling
Abstract

The Ballantrae Complex is located in the area north of the Southern Uplands Fault and Southern Uplands accretionary complex of southwest Scotland. It consists of a tectonically emplaced ophiolite dominated by two serpentinised peridotite massifs known as the Southern and Northern Serpentinite Belts. It also contains smaller serpentinite bodies, including a concealed body proved in a BGS borehole at Knocklaugh Lodge. The highly magnetic serpentinites are associated with pronounced magnetic anomalies that form the focus of this study. The project aims to improve understanding of the shape, size and distribution of serpentinites in the subsurface, by integrating detailed ground-level magnetic surveying, analysis of the bulk magnetic properties of rocks present in the area, Fourier-based upward continuation, and 2D and 3D magnetic modelling techniques. 3D modelling of the Knocklaugh Lodge anomaly identifies a NE-SW-trending, wedge-shaped, fault-bounded sliver of serpentinite beneath surficial boulder clay. A 2.8 km long ground-level magnetic profile extending to the NW from this locality to beyond the NW margin of the Northern Serpentinite Belt was upward continued to 100 m elevation to suppress short wavelength near-surface signals. 2D modelling of these data reveals presence of a large, concealed serpentinite body to the SE of the Northern Serpentinite Belt, and suggests that the boundaries of the major serpentinite units are all steeply dipping. 3D modelling at the regional-scale using data from the National Aeromagnetic Survey further constrains the complex 3D subsurface geometry of the Northern and Southern Serpentinite Belts. It also suggests that a separate linear magnetic anomaly extending ~25 km further to the NE along the strike of the major fault systems in the region is caused by highly magnetic sedimentary rocks of the Ordovician Traboyack Formation. Finally, upward continuation of a ground-level magnetic survey over a raised marine platform near Lendalfoot demonstrates presence of a regional magnetic gradient associated with a deep peridotite source combined with a complex pattern of small-scale, local gradients due to shallow sources that probably reflects variations in the paleotopography of a rocky shoreline beneath the terrace. The Ministry of National Education of the Republic of Turkey

Published
2022

142. Magmatic accretion and thermal convection at the sheeted dike complex–gabbro boundary in superfast spreading crust, ODP Hole 1256D.

Author

Trela, Jarek, Ferré, Eric C., Launeau, Patrick, Bartz, Daniel M., and Morris, Antony

Subjects
*OCEANIC crust, *IGNEOUS intrusions, *MAGMAS, *IGNEOUS rocks, *FRACTURE mechanics, *GEODYNAMICS, *GEOPHYSICS
Abstract

The magmatic processes responsible for accretion of new oceanic plutonic crust at fast-spreading centers remain unclear. Expedition 312, at Ocean Drilling Program Hole 1256D, on the eastern flank of the East Pacific Rise, barely drilled through the uppermost gabbros but offers unparalleled opportunities to constrain deep magmatic processes and the mode of construction of the gabbroic layer. Gabbro 1 and gabbro 2, respectively 52 and 24 m-thick, were intruded in an altered and baked sheeted dike complex. Both gabbros lack a macroscopic fabric and were until now considered isotropic. Here, we use digital 3-D fabric analysis of plagioclase phenocrysts in 33 non-azimuthally oriented samples. In contrast with previous observations, the two gabbros display a distinct and consistent shape-preferred orientation. Both gabbros exhibit magmatic, equilibrated microstructures, with minor submagmatic microstructures. The calculated Rayleigh numbers range between 10 15 and 10 18 , proving that the gabbroic magma was initially undergoing turbulent magmatic flow. Magmatic foliations dip moderately, with a mean of 48° in gabbro 1 and 61° in gabbro 2. Magmatic lineations plunge in gabbro 1 between 1 and 44° (mean 28°), while in Gabbro 2, plunges range from 6 to 69° (mean 41°). These inclined magmatic structures, combined with the inclined magmatic contacts between the gabbros and their host-rock, show that these two gabbro bodies, instead of being horizontal sills, more likely are inclined intrusions that cut obliquely through the sheeted dike complex. Seismic reflection data around Hole 1256D shows inclined reflectors similar to those produced by gabbroic saucer-shaped intrusions in passive margins. On the basis of the inclined fabrics, inclined contacts and the regional seismic data, we propose that the uppermost gabbroic intrusions at fast-spreading centers form with a saucer-shape. This new shape of intrusion, never reported before in the oceanic environment, may constitute a significant component of oceanic accretion. [ABSTRACT FROM AUTHOR]

Published
2015
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143. Evidence of mass failure in the Hess Deep Rift from multi-resolutional bathymetry data.

Author

Ferrini, Vicki Lynn, Shillington, Donna J., Gillis, Kathryn, MacLeod, Christopher J., Teagle, Damon A.H., Morris, Antony, Cazenave, Pierre W., Hurst, Stephen, and Tominaga, Masako

Subjects
*RIFTS (Geology), *BATHYMETRY, *DATA analysis, *WATER depth, *MID-ocean ridges, *LITHOSPHERE
Abstract

Abstract: New regional swath and near-bottom bathymetric data provide constraints on shallow structures at the Hess Deep Rift, an oceanic rift that exposes the crust and upper mantle of fast-spreading oceanic lithosphere created at the East Pacific Rise. These data reveal the presence of a lobate structure with a length of ~4km and a width of ~6km south of an Intrarift Ridge, north of Hess Deep. The lobe consists of a series of concentric benches that are widest in the center of the lobe and narrower at the edges, with a dominant bench separating two distinct morphologic regions in the lobe. There are two end-member possible interpretations of this feature: 1) the lobate structure represents a mass failure with little translation that contains coherent blocks that preserve rift-related lineaments; or 2) it represents degraded tectonic structures, and the lobate form is accounted for by, for example, two intersecting faults. We favor the slump interpretation because it more readily accounts for the lobate form of the feature and the curved benches and based on the presence of other similar lobes in this region. In the slump model, secondary structures within the benches may indicate radial spreading during or after failure. The large lobate structure we identify south of the Intrarift Ridge in Hess Deep is one of the first features of its kind identified in an oceanic rift, and illustrates that mass failure may be a significant process in these settings, consistent with the recognition of their importance in mid-ocean ridges, oceanic islands, and continental rifts. Understanding the structure of the Hess Deep Rift is also important for reconstructing the section of fast-spreading oceanic crust exposed here. [Copyright &y& Elsevier]

Published
2013
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144. Preface

Author

Böhnel, Harald, Hounslow, Mark, Morris, Antony, and Petrovský, Eduard

Published
2004
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145. Pleistocene depositional environments and links to cryosphere-ocean interactions on the eastern Ross Sea continental slope, Antarctica (IODP Hole U1525A).

Author

King, Maxine V., Gales, Jenny A., Laberg, Jan Sverre, McKay, Robert M., De Santis, Laura, Kulhanek, Denise K., Hosegood, Phil J., and Morris, Antony

Subjects
*CONTINENTAL slopes, *PLEISTOCENE Epoch, *GLACIATION, *GLACIAL Epoch, *ICE sheets, *ICE shelves, *CRYOSPHERE
Abstract

The repeated proximity of West Antarctic Ice Sheet (WAIS) ice to the eastern Ross Sea continental shelf break during past ice age cycles has been inferred to directly influence sedimentary processes occurring on the continental slope, such as turbidity current and debris flow activity; thus, the records of these processes can be used to study the past history of the WAIS. Ross Sea slope sediments may additionally provide an archive on the history and interplay of density-driven or geostrophic oceanic bottom currents with ice-sheet-driven depositional mechanisms. We investigate the upper 121 m of Hole U1525A, collected during International Ocean Discovery Program (IODP) Expedition 374 in 2018. Hole U1525A is located on the southwestern external levee of the Hillary Canyon (Ross Sea, Antarctica) and the depositional lobe of the nearby trough-mouth fan. Using core descriptions, grain size analysis, and physical properties datasets, we develop a lithofacies scheme that allows construction of a detailed depositional model and environmental history of past ice sheet-ocean interactions at the eastern Ross Sea continental shelf break/slope since ~2.4 Ma. The earliest Pleistocene interval (~2.4- ~ 1.4 Ma) represents a hemipelagic environment dominated by ice-rafting and reworking/deposition by relatively persistent bottom current activity. Finely interlaminated silty muds with ice-rafted debris (IRD) layers are interpreted as contourites. Between ~1.4 and ~0.8 Ma, geostrophic bottom current activity was weaker and turbiditic processes more common, likely related to the increased proximity of grounded ice at the shelf edge. Silty, normally-graded laminations with sharp bases may be the result of flow-stripped turbidity currents overbanking the canyon levee during periods when ice was grounded at or proximal to the shelf edge. A sandy, IRD- and foraminifera-bearing interval dated to ~1.18 Ma potentially reflects warmer oceanographic conditions and a period of stronger Antarctic Slope Current flow. This may have enhanced upwelling of warm Circumpolar Deep Water onto the shelf, leading to large-scale glacial retreat at that time. The thickest interval of turbidite interlamination was deposited after ~1 Ma, following the onset of the Mid-Pleistocene Transition, interpreted as a time when most ice sheets grew and glacial periods were longer and more extreme. Sedimentation after ~0.8 Ma was dominated by glacigenic debris flow deposition, as the trough mouth fan that dominates the eastern Ross Sea continental slope prograded and expanded over the site. These findings will help to improve estimations of WAIS ice extent in future Ross Sea shelf-based modelling studies, and provide a basis for more detailed analysis of the inception and growth of the WAIS under distinct oceanographic conditions. • A detailed analysis of Pleistocene sediments from IODP Expedition 374 Site U1525 • Three main intervals of deposition between: 2.4 Ma–1.4 Ma, 1.4 Ma–0.8 Ma and < 0.8 Ma • Depositional context for the Hillary Canyon and the Ross Sea trough-mouth fan • Sandy, foraminifera-bearing interval at ~1.18 Ma suggests ice sheet collapse • Ice grounded at shelf edge more often after 1 Ma, TMF prograded over Site U1525 [ABSTRACT FROM AUTHOR]

Published
2022
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146. PALAEOMAGNETIC AND STRUCTURAL ANALYSIS OF THE METAMORPHIC SOLE ROCKS OF THE MERSIN OPHIOLITE, SOUTHERN TURKEY

Author

Çavdar, Buğra, Morris, Antony, and Faculty of Science and Engineering

Subjects
Palaeomagnetism, Metamorphic sole rocks, Suprasubduction zone, Ophiolite, Subduction initiation, ResM
Abstract

The Mersin ophiolite (Tauride Belt, southern Turkey) is a well-exposed Neo-Tethyan suprasubduction zone ophiolite that formed in the Late Cretaceous. It is underlain by metamorphic sole rocks (predominantly amphibolites) inferred to have formed at the top of the down-going plate during subduction. A recent model for exhumation of such rocks from peak metamorphic depths involves slab flattening caused by removal of material from the mantle wedge during fore-arc spreading, implying significant rotation of the sole after formation. Previous palaeomagnetic analysis of non-metamorphosed dykes cutting the Mersin sole rocks indicates a ~45° clockwise rotation of the sole and dykes around a NE-trending, shallowly plunging, ridge-parallel axis. This study aims to quantify any potential rotation of the Mersin sole rocks prior to dyke intrusion to test models of sole exhumation. The amphibolites carry a stable magnetization that is statistically different from that of the dykes, providing evidence for an earlier phase of rotation. However, tectonic interpretation of these data in the absence of paleohorizontal markers cannot be achieved by using standard palaeomagnetic tilt corrections. Therefore, a Monte Carlo approach was used to model potential net tectonic rotation axes after back-stripping the later rotation of sole-hosted dykes from the palaeomagnetic and structural data and by incorporating statistical uncertainties into the analysis. Results suggest that the sole acquired its remanence while the metamorphic foliation dipped moderately (~30-40°) to the ENE and then underwent an early phase of anticlockwise rotation around an inclined, NW plunging axis. This is consistent with a two-stage model involving an earlier phase of exhumation by slab flattening and rotation followed by a later spreading-related rotation around a ridge-parallel axis after accretion of the sole to the base of the lithosphere (and future ophiolite). These rotations around different axes are consistent with a tectonic setting similar to the modern Andaman Sea subduction zone system, where spreading in the suprasubduction zone environment occurs obliquely to the direction of subduction of the down-going plate. Ministry of Education/Republic of Turkey

Published
2019

147. Magnetic fabric, palaeomagnetic and structural investigation of the accretion of lower oceanic crust using ophiolitic analogues

Author

Meyer, Matthew Charles, Morris, Antony, and Faculty of Science and Environment

Subjects
Magmatic petrofabrics, Oman, Gabbro, Accretion models, Melt migration, Tectonic rotations, Semail, Remagnetization, Ophiolite, Palaeomagnetic analysis, Magnetization, Magnetic fabric analysis, Lower oceanic crust
Abstract

This thesis presents the results of a combined magnetic fabric and palaeomagnetic analysis of lower crustal rocks exposed in the Oman (Semail) ophiolite. This has long been an important natural laboratory for understanding the construction of oceanic crust at fast spreading axes and its subsequent tectonic evolution, but magnetic investigations in the ophiolite have been limited. Analyses presented here involve using: (i) magnetic anisotropies as a proxy for magmatic petrofabrics in lower crustal rocks in order to contribute to outstanding questions regarding the mode of accretion of fast-spread oceanic crust; and (ii) classical palaeomagnetic analyses to determine the nature of magnetization in these rocks and gain further insights into the regional-scale pattern of tectonic rotations that have affected the ophiolite. The extensive layered gabbro sequences exposed in the Semail ophiolite have been sampled at a number of key localities. These are shown to have AMS fabrics that are layer-parallel but also have a regional-scale consistency of the orientation of maximum anisotropy axes. This consistency across sites separated by up to 100 km indicates large-scale controls on fabric development and may be due to consistent magmatic flow associated with the spreading system or the influence of plate-scale motions on deformation of crystal mushes emplaced in the lower crust. Detailed analysis of fabrics in a single layer and across the sampled sections are consistent with either magmatic flow during emplacement of a melt layer into a lower crustal sill complex, or traction/drag of such layers in response to regional-scale stresses (e.g. mantle drag). Together, results support formation of the layered gabbros by injection of melt into sill complexes in the lower crust. New anisotropy data from the overlying foliated gabbros sampled at two key localities also provide insights into the style of melt migration at this crustal level. Fabrics are consistent with either focused or anastomosing magmatic upwards flow through this layer, reflecting melt migration beneath a fossil axial melt lens. Previous palaeomagnetic research in lavas of the northern ophiolitic blocks has demonstrated substantial clockwise intraoceanic tectonic rotations. Palaeomagnetic data from lower crustal sequences in the southern blocks, however, have been more equivocal due to complications arising from remagnetization. Systematic sampling resolves for the first time a pattern of remagnetized lowermost gabbros and retention of earlier magnetizations by uppermost gabbros and the overlying dyke-rooting zone. Results are supported by a positive fold test that shows that remagnetization of lower gabbros occurred prior to Campanian structural disruption of the Moho. NW-directed remagnetized remanences in the lower units are consistent with those used previously to infer lack of significant rotation of the southern blocks. In contrast, E/ENE-directed remanences in the uppermost gabbros imply a large, clockwise rotation of the southern blocks, of a sense and magnitude consistent with that inferred from extrusive sections in the northern blocks. Hence, without the control provided by systematic crustal sampling, the potential for different remanence directions being acquired at different times may lead to erroneous tectonic interpretation.

Published
2016

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