The nervous and hormonal control of the melanophores of the minnow was investigated by the techniques of nerve section at various levels, electrical stimulation of nerve tracts and hypophysectomy, used separately or in various combinations. The initial dispersion of melanophores, resulting from denervation, is an active process and not a passive one as maintained by several workers. The. theory that it is activated by pituitary dispersing hormones cannot be upheld, at least as far as the minnow is concerned. The results are more in keeping with Parker'-s theory that nerve section stimulates dispersing fibres. However, Parker's theory is not entirely applicable to the minnow, for the full dispersion of newly denervated melanophores appears to depend partly on the disconnection of central nervous influences at the time of nerve section. There is evidence for both aggregating and dispersing neurohumours in the minnow. This supports Parker's theory of neurohumoura and double innervation in relation to teleost melanophores. Under certain conditions, denervated minnow melanophores respond asymmetrically. Parker's neurohumour conception can therefore be extended. Not only can neurohumours affect entire melanophores, but antagonistic neurohumours can exert localised effects on different regions of one melanophore. Denervated melanophores of the minnow can be activated, under the appropriate conditions, by pituitary dispersing or pituitary aggregating hormones, as well as by neurohumoura. The initial aggregation of denervated mel. anophorea does not result from the stimulation of aggregating fibres by water entering the wound. This does not support the theory of Umrath & Welcher. The possible distribution of dispersing fibres in the autonomic chain and the spinal cord was investigated. Observations were made on the abnormal chromatic responses of minnows confined in tubes. Results indicate that confinement interferes predominantly with the nervous chromatic mechanisms

Coma is an ENU-generated zebrafish mutant line. Homozygous coma larvae are immotile with heart oedema, curved body and kinky tail. Abnormality is found initially in the embryonic midbrain, hindbrain and ventral diencephalon by 28 hpf. The characterization of the mutant defect, using various GFP transgenic background revealed asymmetric folds in the midbrain and lack of differentiation of the isthmus. Further data showed that coma mutant is unable to maintain brain boundaries. No difference observed in the pattern between the coma -I- and its siblings in the whole mount in situ hybridization with MHB and hindbrain markers at 15ss suggests that ’ ,V* boundaries are properly established in the mutants but unable to be maintained. In addition to these early defects, the mutant is unable to form normal motor axons, primary reason for its lack of motility. The mutation in coma was mapped to a 5 cM interval in LG 19. Four of the eighteen SSLP markers tested were found polymorphic and linked to the mutation in a pilot study. Further mapping with the SSLP markers that are polymorphic and linked to the mutation revealed that the region of the mutated gene is around region 19:36.8 in ENSEMBL. Expression pattern analysis of candidate genes in this region together with a complementation test with a published mutant revealed that sfpq is the gene mutated in coma mutant. The protein encoded by sfpq, PSF (polypyrimidine tract-binding protein (PTB)-associated splicing factor), is a RNA processing factor that is important for RNA splicing and transcription. Our current data suggests that PSF is a protein involved in RNA processing-induced motor neurodegeneration such as ALS. Further investigation is required to understand the role of sfpq in motor axon growth and neurodegeneration.

The present investigation was undertaken with the object of determining the food and feeding habits of the commoner gadoids in Manx waters. The work was carried out between October 1956 and August 1958 A total of thirteen gadoid--species were studied and four of these - cod, whiting, coaltish and pollack - were investigated in some detail. In the course of the work knowledge was gained on other aspects of the biology of most of the species, including their habits, abundance and seasonal movements. The effect of these biological aspects on the food and feeding habits of the particular gadoid was noted, While investigating the pelagic postlarval phase of some of the gadoids, whiting with a length-range of 21 to 53 mm were taken in some nubers associated with large scyphomedusae(Rhizostoma octopus L.). Whiting of these sizes have rarely been taken before and little was known of their bionomics. In this work, their food was found to be 'modified as a result of the association with the acyphomedusae; other characteristics of this interesting association are briefly presented.

An investigation was made into the reproductive biology of Labrus bergy1ta, Labrus ossifagus, Creni1abrus melops, Centrolabrus exoletus and Cteno1abrus rupestris (Pisces:Labridae) to examine the occurrence and control of sex-inversion. L.bergylta and L.ossifagus are protogynous, the former monandric and the latter diandric; a distinct colour change is associated with sex-inversion in L.ossifagus. The other three species are gonochoristic and only C.me1ops exhibits sexual dimorphism which involves body colour and size of urino-genita1 papilla. Analysis of age and growth data showed that L.bergy1ta and L.ossifagus are large, slow-growing species of great longevity (maximum 25 and 17 years respectively). Back-calculations of length for age were made from the opercular bones using a modification of Lee's (1920) formula: Ln - c -- O(L On- c). This showed that there is an increase in growth rate for secondary males following sex-inversion, but primary males follow the female pattern. Sex-inversion occurs between the ages of 5-20 (L.bergy1ta) and 7-13 (L.osSifagus), but only a small pr~portion of the females invert. This can be deduced since the sex ratio of secondary males to females is only 0.11 and 0.31 respectively, and females occur in the oldest age groups. The three smaller - gonochoristic species have life-spans of less than 9 i y~ars and males have a faster growth rate than females after age 2. There is no change in the length-weight relationship (calculated using the formula: Log weight (gm) = Log a + b Log length (mm) ) during the life span of any of the species. Sex-inversion in L.bergylta and L.ossifagus was confirmed by histological examination of the gonads. It occurs by atrophy of the oocytes and the gradual development of spermatogenetic cysts throughout the gonad. All 5 species undergo normal annual cycles of reproduction. In L. ossifagus, primary and secondary testes have different structures. The latter retains the lamellar arrangement of tissue and central lumen of the ovary; has a secondary vas deferens running in the wall of the gonad as a series of lacunae; and frequently has remnant oocytes. All testes of L.bergylta examined, had a secondary structure with the single exception of a very young male(7 years) in which neither a primary nor secondary structure could be confirmed In C.melops a small number of unusual males are present (ca. 11%). These have female secondary sexual characters and mature 2 years early, but are not the product of sex-inversion. Histochemical techniques failed to reveal the sites of steroid production in the gonads. The control of sex-inversion by hormones was investigated by injection of fish with methyl testosterone estradiol benzoate, and progesterone. Gonadal inversion was not achieved by these means, but methyl testosterone caused the breakdown of oocytesin L.bergylta and L.ossifagus; and induced a colour change from the red to the blue phase in L.oosifagus.

Deficiency in fukutin-related protein (FKRP) or fukutin results in aberrant glycosylation of a-dystroglycan, a key receptor for basement membrane proteins. There is a broad spectrum of disorders associated with FKRP and fukutin deficiency, ranging from limb-girdle muscular dystrophy to congenital disorders such as muscle eye brain disease and Walker-Warburg syndrome (WWS). fkrp and fukutin were knocked down in the zebrafish with antisense morpholino oligonucleotides (MO). The fkrp, fukutin and dystroglycan MOs each produced a spectrum of comparable phenotypes. With each MO producing a comparable morphant phenotype on morphological examination, it was hypothesised that inferences could be made about similarities and differences in the fkrp, fukutin dystroglycan axis during zebrafish development. The morphants had abnormal muscle fibres, including disruptions of the vertical myosepta and sarcolemma. Disorganised retinal layering in the eyes was found in both fukutin and fkrp morphants. Dysplasia of the lens was observed in most fukutin morphants and some of the fkrp morphants with a severe phenotype. Structural changes in basement membranes at 1-3 days post fertilisation (dpf) were investigated. The perturbation observed across the inner limiting membranes may account for the lens dysplasia. Cell density of the granular epithelium in the photoreceptor cell layer was found to be lower in both morphants with the least density in fukutin knock-downs, which may result from a disruption of the external limiting membrane. This leads to the conclusion that fkrp and fukutin are essential for membrane integrity in the eye and muscle of developing zebrafish. A transgenic zebrafish line expressing enhanced green fluorescent protein (EGFP) in vascular endothelium from the fli-1 promoter was used to investigate early vascularisation. In all morphants, including dystroglycan knock downs, the intersegmental vessels failed to reach the dorsal longitudinal anastomotic vessel at 1dpf. Additionally, in the fkrp and fukutin morphant the eye vasculature was abnormal. Interestingly, no change was observed in the eye vasculature of the dystroglycan morphants suggesting that fkrp and fukutin may modify proteins other than α-dystroglycan in the eye.

Personality in animals describes a suite of correlated behavioural traits that distinguishes one individual from another. One important personality measure is boldness, which is related to intraspecific differences in responses to novelty, levels of activity and aggressiveness, propensity for exploration, and capacity for learning and memory. Personality and boldness have previously been linked with physiological responses to stress, termed coping styles, wherein lower stress responsiveness often correlates with bolder behaviour. Variation in these traits has important implications for how animals respond to environmental challenges. Personality and stress responsiveness are both also partly heritable; a greater understanding of the genetic control of behavioural and physiological traits is therefore necessary to understand how individual differences are maintained in the face of natural selection, and how genes can control changes in behaviour and physiology. Boldness and behavioural plasticity was therefore examined in the rainbow trout, Oncorhynchus mykiss Walbaum, which provides an excellent model since the behaviour and physiology of this economically important species has been well-studied. Throughout, boldness was assessed using novel object tests, where latency to approach to within 5 cm of an object was the primary determinant. Trout which approached within 180 s were considered bold, those which did not approach within 300 s as shy, and the remainder as intermediate which were discarded from analysis. Boldness was consistent over time in two lines of rainbow trout bred for a divergent response to stress, but no correlation was found between boldness and either stress responsiveness or gene expression, in contrast to expectations. Stress responsiveness was, however, strongly linked with gene expression: a suite of candidate genes was uniformly upregulated in low stress-responding trout compared to high-responders, suggesting fine control of hormones and receptors throughout the stress response may occur downstream of gene expression. Outbred bold rainbow trout placed into a group of either completely bold or completely shy trout tended to become shyer, whereas initially shy trout did not display any behavioural plasticity. Likewise, bold trout exposed to predation threat in combination with different levels of feed availability modified 'their behaviour seemingly dependent upon the combination of risk level and internal state. Shy trout, again, were less labile. This is in contrast to coping style theory which suggests shy, reactive animals have more behavioural flexibility than bold, proactive individuals. When exposed to variable abiotic factors - increased temperature and reduced dissolved oxygen content - both bold and shy fish exhibited some behavioural change dependent upon the combination of factors. When exposed to these stressors and challenges, plasma cortisol levels more closely matched behavioural profiles such that shy trout generally had a greater stress response than bold trout, and this could be linked to exposure to threat or temperature change. Furthermore, gene expression profiles corresponded with predation threat: genes coding for corticotrophin releasing factor (CRF), ependymin and y-aminobutyric acid A (GABAA) increased in expression under increasing threat levels, indicating these genes were involved in the response to this particular challenge. These results thus show the existence of personality in rainbow trout, linking responses towards novelty with levels of activity and identifying physiological and genetic correlates to these behavioural traits. Boldness was shown not to be a fixed trait but, instead, dependent upon social, environmental, nutritional and energetic state and on intensity of risk. Bold trout generally altered their behavioural strategy in an adaptive manner according to both context and state yet shy individuals remained shy. These empirical data highlight the importance of taking individual personality into account when assessing molecular, physiological and behavioural responses to stimuli. Furthermore, these data provide new insights into intraspecific variation within a variety of contexts that may be used to fuel theoretical models of the evolutionary and ecological significance of animal personalities.

Lampreys (Order Petromyzontiformes) have existed for over 365 million years and are considered the most ancient group of living vertebrates. Given the socio-economic, cultural, and ecological consequences of declining lamprey populations, it is imperative to address declines by implementing effective conservation management. This thesis explores the conservation issues affecting the European lamprey species pair Lampetra fluviatilis and Lampetra planeri and offers a holistic approach to their management and conservation in relation to anthropogenic impacts. The rapid development of small-scale hydropower provides substantial risk to migrating biota. At the site of an Archimedes screw turbine, damage rates to lampreys that passed through the screw were low (1.5%) and distinct seasonal, and diel, patterns of migration were exhibited by recently transformed juvenile and larval lampreys. Results indicated longer periods of impingement risk than expected. Cumulative potential impacts of multiple hydropower sites on downstream fish passage (including lampreys) should, however, be considered by regulatory agencies when planning hydropower development within catchments. Anthropogenic barriers were also found to intensify differentiation between L. planeri populations and anadromous L. fluviatilis populations. Gene flow was consequently found to be asymmetric due to the barriers allowing downstream movement, whilst obstructing active upstream migration. Samples of 543 European river lamprey Lampetra fluviatilis and European brook lamprey Lampetra planeri from across 15 sites, primarily in the British Isles, were investigated for 829bp mtDNA sequence and 13 polymorphic microsatellite DNA loci. Contrasting patterns of population structure were found for mtDNA (which revealed no differentiation between species) and microsatellite DNA markers. Microsatellite markers revealed strong differentiation among freshwater-resident L. planeri populations, and between L. fluviatilis and L. planeri in most cases, but little structure was evident among anadromous L. fluviatilis populations. There is also evidence that there has been some degree of gene flow between L. fluviatilis and L. planeri since these populations were established. There is much debate as to whether lamprey paired-species constitute distinct species or are divergent ecotypes of a single polymorphic species. Overall, these findings are suggestive of multiple independent divergences of L. planeri from an anadromous ancestor (i.e. L. planeri are polyphyletic). Focus of conservation and management efforts, therefore, needs to be directed towards ensuring the longitudinal connectivity within rivers, and the continued existence of the specific habitats necessitated within lamprey life-cycles. Molecular techniques should be applied to identify genetically differentiated populations of freshwater-resident lampreys. Appropriate measures, such as, the designation of a network of Special Areas of Conservation (SACs), and recognising these populations as distinct Evolutionarily Significant Units, should also be implemented to ensure the survival of these populations.

Anthropogenic noise is a global pollutant, present in both terrestrial and aquatic ecosystems. Due to high species diversity and the characteristics of sound propagation in water, noise pollution in aquatic environments may be more detrimental than in terrestrial environments. Underwater noise affects the behaviour of mammals, fish and invertebrates, with changes to communicative and spatial behaviour among those frequently reported. However, relatively little work examining the effect of underwater noise on reproductive behaviour has been completed. Reproduction is essential for the proliferation of life. Therefore, investigating how anthropogenic noise may affect it is important. I used the biparental species, Amatitlania nigrofasciata, as a model system to study the effect of underwater noise pollution on multiple stages of reproduction. Using playback experiments, I firstly tested the effect of short-term noise on behaviour and then examined the effect of longer-term noise on: (1) pairing behaviour, (2) nest-site selection, (3) parental defence, (4) parental care and (5) reproductive success. I found that both short-term and long-term noise affected behaviour and that behaviour was affected throughout the reproductive cycle. I also established noise as a proximate factor influencing nest-site selection and provide evidence for multiple mechanisms through which noise could affect behaviour. However, behavioural changes in response to noise did not translate into negative consequences for reproductive success. Noise increased parental investment, by increasing parental defence and brood provisioning behaviour. This could reduce the resources parents can invest in subsequent broods. Therefore, noise may affect the reproductive success of future breeding attempts. My findings provide novel insight into how changes to the acoustic environment affect reproductive behaviour.

The cytology of the pronephros of the three species of lamprey larvae, Lamnetra planeri. L. fluviatilis and Petromyzon marinus, at the pronephric stage of excretion and during its subsequent degeneration, has been investigated with the optical and electron microscopes. The pronephros is a paired, segmental organ located in the cardiac region, each pronephros consisting of two functional units: a single large glomus and an aggregation of 3-8 tubules. Ultrastructurally, both have been found to be strikingly similar to their homologues in opisthonephric, mesonephric and metanephric kidneys. The principal dissimilarities between the functional lamprey pronephros and the kidneys of the higher vertebrates are, in general, due to the less complex structure and arrangement of the cells and the tissue of the pronephros. The glomus is composed of the usual three cell types found in all vertebrate glomeruli, although in the glomus they exhibit a less complex internal structure. There is no juxtaglomerular apparatus in the glomar artery, which arises from the dorsal aorta. Multiple filtration slit membranes are found between the foot processes of the epithelium, and the endothelial fenestrae lack membranes. There is no Bowman's capsule. Filtrate from the glomus passes into the coelom and coelomic fluid is collected by ciliated nephrostomes which lead to the tubular portion, which is enveloped by the anterior cardinal vein. The nephrostome is composed of an external funnel and a short, internal neck leading to the proximal tubule, which is the longest of the tubular sections and divided into two segments. The proximal tubule is connected to the shortar distal tubule by a abort, undifferentiated intermediate segment. Each pronephros is drained by a duct which empties into the cloaca. The fine structure of the proximal and distal tubules, while exhibiting minor differences, is almost identical to the homologous tubules of the mammalian metanephros, but the tubules do not display the greater degree of subdivision found in other vertebrates, particularly mammals. The ultrastructure of the pronephric duct is vary similar to that of the preceding distal tubule. Degeneration of the glomus begins in the latter part of the first year in all species. The capillaries become occluded with a dense, amorphous material and cellular material derived from proliferating endothelial and mesangial cells. The axial portion of the glomus increases is volume by further mesangial proliferation, and numerous reticular and collagenous fibres are deposited in the mesangial matrix. In the year before metamorphosis, the endothelial and mesangial cells begin to appear necrotic, but the epithelial cells are unaffected, and the glomus does not disappear entirely until metamorphosis. The tubules begin to atrophy in the first year, the proximal tubules of the most anterior segments being the first to show signs of degeneration. Lycosome-like bodies appear in the cytoplasm, many cells rupture and the lumens become blocked with cellular debris and subsequently with invading macrophages. This occlusion is followed by a swelling of the tubules, phagocytic invasion increases, the swollen tubules collapse and the remaining nephric cells are resorbed. The distal tubules and the tubules of the posterior segments follow in sequence, and by the last year of larval life all traces of the tubules have disappeared, except the nephrostomes which, although slightly altered, continue to function, passing coelomic fluid into the anterior cardinal vein. The pronephric duct usually persists in the undifferentiated region behind the pronephros, and can often be traced to the cardiac region in the adult. The changes which occur with age, and the death and resorption of the cells of the pronephros, are shown to have several points of similarity with changes which occur with increasing age and pathological conditions in mammalian kidneys. The only interspecific difference found between pronephroi of the three species studied occurs in the tine of onset and the rate of tubular degeneration. In L. planeri, atrophy begins earlier and is completed sooner than in P. marinus; onset and completion of tubular degeneration in L. fluviatilis appears to be intermediate to the other two species. The possible reasons for this difference are discussed in relation to the life history of lampreys, and it is concluded that earlier and faster degeneration of the tubules is related to the trend towards neoteny in L. planeri. Primary experimental evidence shows that the pronephros is capable of responding to changes in the osmotic pressure of the environment by adapting certain features of the tubular structure, principally the degree of lateral and basal interdigitation and the size of the intercellular spaces, to facilitate increased or decreased water resorption. The ultrastructure of the pronephros is discussed in relation to the ultrastructure of other kidneys, and pronephric function is considered, both by reference to the experimental results and by extrapolation from ultrastructural and functional studies of the kidneys of higher vertebrates. This investigation shows that although there are minor differences the essential ultrastructural similarity between the pronephros and the opisthonephros, mesonephros and metanephros suggests that the former should not be regarded as the ancestral excretory organ of vertebrates. On the contrary, the evidence presented here indicates that the regions of the vertebrate excretory system are serially homologous. Support is thus given to the holonephric theory of the evolution of the kidney in vertebrates.

The objective of the experiments contained within this thesis was to provide further insight into the social learning capabilities of threespined sticklebacks and the factors affecting the transmission of information through populations. There are a number of previous studies which provide evidence that both threespined and ninespined sticklebacks possess the ability to learn socially under a range of contexts, such as foraging, anti-predator behaviour, mate choice, and cooperation. The studies presented in this thesis aim to extend this knowledge and shed light on the social learning processes used. Evidence was found to support previous opinion that threespined sticklebacks are capable of using a number of social learning processes, including local enhancement, stimulus enhancement, and the social enhancement of food preferences. However, therewas no evidence to suggest that either threespined or ninespined sticklebacks are capable of using the social learning process of delayed local enhancement under a shelter choice context, a process which both species have previously been shown to use under a foraging context. This thesis also explores the effect of the social network within shoals of threespined sticklebacks upon the transmission of novel foraging information. It was discovered that both prior association preferences and prior diet have an effect on the order in which individuals discover a novel foraging task.