PhD Studentships: Sensory Ecology, Parasites and Mate Choice in the Guppy, POECILIA RETICULATA

Jessica Stephenson

Cardiff University & Bristol University

Supervisor(s): Joanna Cable & Gabrielle Archard, & Julian Partridge

My research focuses on the way information from different sensory systems (vision and olfaction) interact to inform animal decisions. I am using the guppy-gyrodactylid model system to test how parasitism affects this interaction in a mate choice context. In dissecting the mechanism by which parasitism can alter mate choice in this host, the project will increase understanding of how sexual selection changes in parasitized populations. Furthermore, this could provide an explanation for the maintenance of anomalously high Major Histocompatibility Complex (MHC) allelic diversity in parasitized fish populations.

How an individual’s mate choice preferences change over time is an understudied area of evolutionary ecology. Condition-dependent variation in mate choice preferences between individual female guppies has been demonstrated. It is likely, though little tested, that there is also within-individual variation in preference because condition will change through time. One mechanism by which preferences may vary both between and within individuals is through alteration in the rank females attribute to each of the several cues used during mate choice. These cues in guppies have been well studied; in healthy females mate choice appears to be based largely on visual cues, females prefer males with intense carotenoid colouration and high display rate. The role of olfaction in guppy mate choice has received little attention and is uncertain, though it is through olfaction that animals (including fish) assess MHC compatibility. Susceptibility to parasites is linked to MHC genotype in guppies, so choosing mates based on MHC compatibility is likely to increase guppy reproductive fitness. Olfactory cues may also serve to ‘prime’ the visual system, as has been found in zebrafish. I am using a range of behavioural experiments to test hypotheses relating to condition dependent, within individual variation in the use of information from different sensory modalities in a mate choice context.


Cardiff School of Biosciences,
Biomedical Sciences Building,
Museum Avenue,
CF10 3AX


PhD Studentship: A Genomic approach to the Genetic Impact of an Invasive Congener on a threatened native pond fish

Daniel Jeffries

University of Hull & Cefas-Lowestoft

Supervisor(s): Bernd Hänfling, Lori Lawson-Handley & Gordon Copp

Research on invasive species and invaded communities is essential to understanding and predicting biodiversity change. Furthermore, introduced species are excellent model systems with which to address fundamental questions in biology. However, biological invasions can have dramatic impacts on native species and this appears to be the case for the crucian carp Carassius carassius, which is native to northwestern Europe (including southeast England), and under threat from non-native congeners goldfish C. auratus and gibel (a.k.a. Prussian) carp C. gibelio. Conservation efforts for C. carassius are hampered by the taxonomic ambiguity which exists between C. carassius, C. auratus and C. gibelio; the problems in classifying and identifying separate Carassius spp. have introduced doubt regarding the current distributions of all Carassius spp. Consequently, impact assessment has been difficult; for example, it has only recently been demonstrated that around 70% of pure C. carassius populations in Norfolk, UK have been replaced by non-native Carassius species in the past 30 years.

In order to provide impact assessments in invasive systems, conservation geneticists have previously concentrated their studies on the lowered fitness and adaptability of native species in small populations due to the loss of genetic variability. These studies almost exclusively use near-neutral genetic markers, which cannot be a proxy for genetic variation in genes which have selectively important functions. Furthermore, neutral markers will lose genetic variation more rapidly than those under selection, with there being no correlation between molecular marker heterozygosity and heritabilities. There is likely therefore to be a difference between the impact of bottlenecks and/or climate change on genetic variation in neutral and non-neutral genes. Additionally, the study of hybridisation has been carried out previously using mainly only a small number of molecular markers, which do not have sufficient power to reveal the introgression of single genes. These limitations have left two fundamental evolutionary questions unanswered: to what extent is adaptively important genetic variation affected by bottlenecks in small, isolated populations, and, what are the genetic effects associated with environmental change (through invasive species and climate change) on fragmented populations?

With the development of next-generation sequencing, it is now feasible to address these research gaps. Next generation sequencing techniques allow for genome-wide sequencing, including selectively functional genes, thus providing a better representation of the genetic variation within individuals and populations and allowing for comparison between the behaviour of these genome regions during bottlenecks. Furthermore, these techniques allow for the identification of small regions in the genome of native species that have introgressed from non-natives or vice versa. Simultaneously, the genomic analyses of this system, in conjunction with microsatellite analyses, will shed light on the genetic structure of C. carassius populations in both the UK and continental Europe, providing the means to put forward comprehensive and much needed Biodiversity action plans for this threatened species.


Daniel Jeffries
Evolutionary Biology Group
Hardy Building
University of Hull


PhD Studentship: The Structure and Function of Social Networks in a Marine Predator

David Jacoby

Marine Biological Association & University of Exeter

Supervisor(s): Darren Croft and David Sims

It is well documented that many species of shark exhibit frequent, and often sexually segregated, aggregation behaviour during the resting phase of their diel cycle. This behaviour has been linked in the past to habitat or environmental preferences, foraging opportunities and reproductive behaviour, but little attention has been paid to the role of social preferences in these aggregations. Social network analysis is a theoretical framework which has been recently adapted to explore how animals interact through space and time, and consequently what impact this has on the transmission of information or disease between conspecifics. With elasmobranchs exhibiting a larger brain mass to body mass ratio than teleost fish, there is potential for the formation of complex social systems within these aggregation events but this has never been examined.

This project uses the small spotted catshark (Scyliorhinus canicula) as a model species with which to study social preferences and network construction in elasmobranchs. Using repeatable and controlled laboratory network experiments this project aims to determine the role of kinship and familiarity on the development of social structure in this species and assess how habitat complexity is likely to influence decisions about social behaviour. To give context to the laboratory studies, nearly 50 adult catsharks have been tagged acoustically and are currently being tracked in the wild with passive telemetry receivers on the seabed. Network analysis will not only shed light on the degree of co-occurrence of these sharks in the wild but will also be adapted to understand how environmental variables influence the ways in which individual, or groups of, animals move within and between habitat areas. The technique adapted for this study will have implications for the analysis of telemetry data from a wide variety of both marine and terrestrial animals.


Griffiths, A.M., Jacoby, D.M.P., Casane, D., McHugh, M., Croft, D.P., Genner, M.J. & Sims, D.W. First analysis of multiple paternity in an oviparous shark, the small-spotted catshark (Scyliorhinus canicula L.). Journal of Heredity (in press) doi: 10.1093/jhered/esr112

Jacoby, D.M.P., Croft, D.P. & Sims, D.W. Social behaviour in sharks and rays: analysis, patterns and implications for conservation. Fish and Fisheries (in press) doi: 10.1111/j.1467-2979.2011.00436.x

Jacoby, D.M.P., Busawon, D.S. & Sims, D.W. (2010). Sex and social networking: the role of male presence on social structure of female shark groups. Behavioral Ecology 21, 808-818.


The Marine Biological Association of the UK
The Laboratory
Citadel Hill

PhD Studentship: Validation and Development of Otolith Microchemistry in free-ranging Marine Fish

Anna Sturrock

University of Southampton

Supervisor(s): Dr Clive Trueman, Dr Ewan Hunte

The aim of the project is to determine the relationship between otolith microchemistry and the ambient environmental conditions experienced by free-swimming plaice (Pleuronectes platessa L.). By matching known spatial and temporal movements with otolith composition, we hope to validate and develop otolith microchemistry as a useful tool in marine fish spatial ecology, and will use the results to complete our understanding of the lifetime movements and stock structure of North Sea plaice.

Data records from free-ranging plaice tagged with electronic data storage tags (DSTs) will be used to provide an independent measure of location with which to compare trace element and stable isotope composition of concomitant otolith material. Also, the physical and chemical environments experienced during the plaice lifecycle will be analysed and used to construct predictive maps of otolith composition.

Otolith microchemistry provides a promising ‘natural tag’ with which to retrospectively track movements of wild fish, but it has yet to be applied widely to fully marine species. The project aims to provide in situ validation of this technique and produce predictive maps that could ultimately remove the need for extensive otolith reference collections for future studies in the North Sea. Also, the information on plaice spatial dynamics derived from this study will be considered both in terms of implications for current management strategies, and how data derived from otolith microchemistry might best be applied to marine fisheries management in the future. |

PhD Studentship: Extent and Drivers for Cryptic Benthivory in ‘Pelagic’ Ocean Sunfish

Natasha Phillips

Queen’s University Belfast

Supervisor(s): Jon Houghton and Chris Harrod

The ocean sunfish (Mola mola) is often described as an inactive, obligate predator of gelatinous zooplankton, but new research suggests these long held beliefs need significant revision. A recent study has revealed evidence of cryptic benthivory in juveniles and this project aims to examine the extent of and ecological drivers for benthivory in sunfish ontogenetically. Specifically, we hypothesize that ocean sunfish have a counter-intuitive life history tactic where small sunfish target high energy, benthic prey becoming more pelagic as they grow and shifting to an under-utilised niche as specialist foragers of gelatinous prey.

By combining stable isotope analysis (SIA) of diet with electronic bio-logging of behaviour, the energetic basis, timing and extent of this strategy can be quantified. In collaboration with Monterey Bay Aquarium, USA, techniques will be developed on captive sunfish before being deployed in the field. Tri-axial accelerometers fitted to captive sunfish will provide proxies of energy expenditure for discrete behaviours, and these data can then interpret the accelerometer readings of wild sunfish. The captive sunfish will also enable development of non-lethal sampling techniques for SIA to estimate isotopic fractionation and turnover through diet switch experiments.

Field work will be in Camogli, Italy where there is a local abundance of ocean sunfish and ongoing collaborations with the fishery and Marine Protected Area authorities. Using wild specimens, a description of ocean sunfish age and growth will help determine whether benthivory is restricted ontogenetically. The trophic ecology of wild sunfish will be analysed using gut content analysis and SIA (δ13C, δ15N) to characterise diet. These data will then be compared between populations using ocean sunfish samples collected by colleagues globally.

Overall this project aims to provide an understanding of the cryptic ecology of a large, pelagic consumer that may play a complex role in ecosystem function, alongside policy and conservation recommendations recognising the complexities associated with mixed benthic-pelagic foraging strategies.


Twitter: @sunfishresearch

PhD Studentship: Integration of Sea Angling Associated Catch and Mortality for Stock Assessment

Graham Monkman

University of Bangor & CEFAS

Supervisor(s): Michel Kaiser, Kieran Hyder and Franck Vidal

There are c. 1 million recreational sea anglers (RSA) in the UK, spending annually over £1.2 billion and their removals of marine fish can be quantitatively comparable to commercial landings, as revealed by landings of the European sea bass, Dicentrarchus labrax. Hence angling removals should be included in stock assessments and fisheries management, accounting for catch and release and post-release mortality rates.

RSA catch has only been included in stock assessments of Baltic cod; a gap recognised by the European Commission, and in the Common Fisheries Policy that requires members to report on catches by RSA for some species to give a clearer picture of how fishing affects stocks. RSA data on commercially significant species are also required at a local level under the Marine and Coastal Access Act to provide an evidence-base when balancing the needs of marine environment users. However, national RSA assessments are expensive and complex, especially in the UK where sea angling is unlicensed, so there is little evidence to inform the development of a policy for UK sea angling despite the sector’s importance.

My research will seek to scope, develop and validate transferable, innovative techniques in the capture of RSA data on marine fish species of recreational and commercial importance, primarily within ICES ecoregions E and F. This work will comprise three synergistic strands:

To engage with the UK RSA community to determine the extent of existing catch data recorded by anglers and to collate those data to construct time series of catches and compare against existing fisheries independent and dependant time series.

To develop, evaluate and pilot practical, reusable low cost technological solutions to complement RSA data recording, including natural language processing of social media sources; machine vision in species identification, and optical character recognition in form processing complemented with SMS, email and mobile solutions and their application to local and national angler survey programmes.

To evaluate the viability and define success criteria for a citizen science programme on the ongoing assessment of recreational sea angling, based on the outcomes of the preceding strands.

School of Ocean Sciences
Bangor University
Menai Bridge
LL59 5AB


PhD Studentship: Differential Susceptibility to Copper in Wild Populations of Three-spined Stickleback (Gasterosteus Aculeatus).

Lauren Laing

University of Exeter

Supervisor(s): Eduarda Santos & Rod Wilson

Most aquatic environments in the UK and worldwide have been affected by anthropogenic environmental stressors. Such stressors vary from chemical pollution to habitat fragmentation and to changes in abiotic parameters such as temperature and dissolved oxygen or carbon dioxide. Populations of fish inhabiting these environments are often exposed to combinations of stressors and, as a result, their sustainability is critically dependent on their ability to adapt to the local environment. Despite this, legislation to protect the environment from chemical contamination is often based on toxicological measurements conducted under optimal laboratory conditions and that does not take into account the variation in susceptibility of wild populations or the multiple stressors affecting these populations.

For metals, extreme cases exist of fish populations that can survive in highly contaminated waters, including a brown trout population in the River Hayle, where concentrations of metals far exceed the LC50 for this species. Furthermore, even for populations of fish inhabiting relatively un- impacted waters, their toxicological responses to metals can vary significantly. This highlights the need to understand natural and exposure-induced variations in the response of fish to pollutants, in order to appropriately manage and protect fish populations in their natural environment.

My research explores three key questions, firstly to determine if wild populations of three spined sticklebacks exhibit differential susceptibility to copper and if those characteristics can be inherited under control conditions. Secondly, my research aims to determine if differential susceptibility can be induced by exposure to copper during early life. Thirdly, I plan to investigate the fitness cost associated with differential susceptibility to copper in this species.

Together, this research will allow for a greater understanding of the variation in the responses to chemical stressors in wild populations, how they are induced and maintained and what are the consequences of changes in susceptibility to a pollutant on other parameters of fundamental importance to population sustainability. The data will build on previous data generated at Exeter, and will have implications for toxicity testing and regulation and for the management of wild fish populations.

My report on my attendance at the Canadian Conference for Fisheries Research is here

Uren Webster, T. M., Laing, L. V., Florance, H. & Santos, E. M. 2014. Effects of glyphosate and its formulation, Roundup, on reproduction in zebrafish (Danio rerio). Environmental Science & Technology48, 1271-1279.


College of Life & Environmental Sciences
University of Exeter