Due to human activities freshwaters are experiencing declines in biodiversity far greater than those in the most affected terrestrial and marine ecosystems, consequently freshwater fishes are by far the most affected group of vertebrates. This situation stands true for Mexican freshwater fishes and their corresponding ecosystems. In this respect, Mexico has a long history of environmental policy, and seeking to protect its biodiversity, the country has carried out a series of important initiatives in response to the adoption of the Convention on Biological Diversity (CBD), such as the creation of the National Biodiversity Commission in 1992, the elaboration of the National Biodiversity Strategy, regional action plans, as well as conservation strategies for terrestrial and marine species and environments, but unfortunately, little has been done in relation to the conservation of freshwater species, nor the ecosystems they live in. With this in mind, the main aim of this study is to analyze the spatial distribution of the Freshwater Fishes of Mexico, their conservation status, and to develop a conservation strategy for species with imminent risk of extinction. In order to develop the strategy four basic phases were taken: (1) assessment of the freshwater fishes of Mexico, (2) determination of conservation priorities, (3) identification and diagnosis of problems, and (4) planning solutions. These were achieved through a series of different methodologies for each particular case. The first part of the assessment phase consisted in developing an updated species list of Mexican freshwater fishes that resulted in a working list of 616 fish species grouped in 61 families for Mexican freshwaters (265 are Mexican endemics). Globally there are approximately 12,000 described freshwater fish species, so results show that Mexico holds 5.1% of the global freshwater fish diversity. This is a large figure considering that the Mexican territory represents only 1.3% of the world global land area. The second part of the assessment phase consisted in developing a study of richness and endemism which was crucial for identifying hotspots and consequently for directing conservation efforts. This was done by mapping and overlaying individual species distributions by means of geographical information systems based on museum data. The results of this study confirmed several previously proposed centers of freshwater fish richness (Southeastern Mexico, the Mesa Central, the Bravo-Conchos river system and the Panuco and Tuxpan-Nautla rivers). Seven areas with high CWEI endemism values were identified, but the valley of Cuatrociénegas was recognized as a true center. An alarming result was the identification of a “Ghost” center of endemism (Llanos El Salado) in Southwestern Nuevo León, where the six endemic Cyprinodont species that were present in this center are all extinct or extinct in nature. 49 single site endemics were identified that are distributed all over Mexico, but it is noteworthy to mention Chichancanab lagoon in the border between Yucatan and Quintana Roo, where a flock composed of 6 endemic Cyprinodonts is present. Three hotspots of richness + endemism were identified for Mexico, the most important of which is the Mesa Central where impacts by human activities have had a detrimental effect on fish populations. In order to determine conservation priorities the risk of extinction for each of the 616 species was assessed according to the IUCN Red List Categories and Criteria: Version 3.1. Results show that 218 species (36%) in 25 families are classified as threatened, 49 are critically endangered (8%), 82 are endangered (14%), 88 are vulnerable (14%). With a total of 160 threatened species, five families compromise 73% of the total, these are Cyprinidae with 55 threatened species, Goodeidae with 38, Poeciliidae with 23, Atherinopsidae with 22 and Cyprinidontidae with 21. Lost fishes, both extinct and extinct in the wild represent 3% of the total with 20 species, 15 of which are Mexican endemics. There are only 18 species (3%) classified as Near Threatened, these belong to 9 families, most diverse of which is Poeciliidae with 7 species. Data Deficient species account for only 2% of the total. Over half of the species (56%) are considered as Least Concern. These figures are very similar to those found for European freshwater fishes, but differ (are worse) from what has been found for Africa, and for global data. Once these phases were completed, an assessment was carried out on the Mexican legal and institutional framework related to freshwater fish species conservation, as well as the effectiveness of ongoing biodiversity conservation strategies by means of on ex-post analysis based on the two Mexican governmental policies related to ecosystem and biodiversity conservation, which are those related to Protected Areas and Conservation of species at risk, implemented by the National Commission on Protected Areas. Results show that even though there have been many successful strategies in the terrestrial realm, over the past 16 years there is a tendency of more freshwater fish species being imperiled. So it is fair to say that conservation programs have not had a positive impact on freshwater fishes. Due to the large number of threatened freshwater fish species found, within such a large country, with limited economic resources for species conservation actions, a decision was made to identify as conservation targets, those species with imminent risk of extinction. After applying a prioritization method, 45 species within nine families, distributed in 30 different sites were identified as those with the highest extinction risk. With the information produced in the previous sections a conceptual model was developed that included scope, vision, and the conservation goal of preventing imminent extinctions. Direct threats were then identified for these sites (recreational activities, water management/use, water pollution and invasive species), and from these contributing factors. Based on the former, 10 general actions are proposed to minimize the impact of these contributing factors, and a case study with Notropis boucardi from the higher Balsas river basin is presented as an example of how these actions can be applied to achieve conservation results. In general terms it can be said that by collating and analyzing data in a systematic manner, by using geographical information systems, and by discussing the results in the context of contemporary theories or views related to conservation practice, the present study has not only contributed to the knowledge of Mexican freshwater fish species, their conservation status and threats, but has set the basis for the implementation of specific conservation actions for species with imminent risk of extinction. It is clear that much work is still needed in order to change the precarious situation of Mexican freshwater fishes and their habitats, but while the Federal Government needs to work harder in aspects such as water treatment and sanitation, there is an opportunity in State and Local governments, that could take the lead in protecting their critically endangered freshwater fish species. Fortunately the database produced for this study, as well as the ten conservation actions identified can serve as the starting point for specific local conservation initiatives.

No description available.

This thesis investigates the interactions between some different elements of colour in group-living freshwater fishes, oddity in groups and the effects of these on observed behaviour. In the early chapters (2-4), I address the rapid colour change of which such fishes are capable. I investigate how social and habitat preferences interact with this morphological change, showing that physiological colour change can be as a direct result of changing habitat colour, and that the resulting body colour influcences social and habitat choice. I reveal a second function to this colour change, in dominance signalling, and discuss the social and other costs associated with physiological melanic colour change. The later chapters are focussed on some other aspects of oddity and risk in social behaviour of freshwater fishes. In chapter 5 I test a model predicting mixed phenotype grouping, concluding that prey animals must balance the relative risks of oddity and conspicuousness in their social decisions, potentially leading to the evolution of mixed phenotype grouping as a response to predation risk alone. Chapter 6 further investigates body size-oddity in the Trinidadian guppy, revealing body-size differences in social preferences. I elaborate on this finding in chapter 7 by discovering that large prey are at greater risk than small prey, given their oddity in a group, and that the differing social preferences are as a result of 'poor' decision makers being more easily captured and removed from the population by predators, leaving only 'good' decision makers to grow large .

No description available.

No description available.

This study aimed to describe the key consequences of three invasive species within freshwater systems, namely Lagarosiphon major, Squalius cephalus and Hemimysis anomala. I utilised a combination of tried and tested traditional methods such as age, growth and diet analyses alongside modern methods such as stable isotope analysis (SIA) and assessment of functional responses. Research questions or hypotheses were examined to assess the impacts (if any) an invader was having on ecosystem function within freshwater systems. The research methods applied and developed in this study will help ecologists quantify the direction of ecological change after an invasion has taken place. It may also help ecologists to forecast the effects an invader is likely to have in an ecosystem. In Lough Corrib the potential impacts of a L. major invasion were assessed. The findings showed that macroinvertebrate assemblage structure differed between L. major dominated habitats and native macrophyte habitats. Fish captured in invaded and native habitats differed in key, characteristics. SIA revealed that L. major made little contribution to the food-web. In the River Inny, the non native fish Squalius cephalus was discovered in 2005. This study assesses the potential for this species to have an ecological impact. 1 concluded that the population size was low. SIA revealed that the diet of this species overlapped that of several species of conservation concern. This study contributed to the probable eradication of this species from Ireland. 1 also describe the most recent distribution of the Ponto-Caspian invader Hemimysis anomala in Ireland including its spread to the River Erne catchment. In addition, functional response experiments showed the potential for this species to be a voracious predator when compared to its closest native ecological equivalent.

D’après le dernier rapport du groupe d'experts intergouvernemental sur l'évolution du climat (GIEC), le réchauffement climatique devrait se poursuivre au cours du siècle prochain. La température atmosphérique moyenne pourrait augmenter de 0,3°C à 4,8°C avec des valeurs extrêmes allant de 1°C à 6°C en 2100. Ces changements de température auront des conséquences directes et indirectes sur l’ensemble de la biodiversité et plus particulièrement sur les poissons qui sont des animaux poïkilothermes. Dans cette étude, trois espèces ont été choisies en prenant en compte leur stratégie de reproduction et leur différence de tolérance thermique : la truite commune (Salmo trutta), le brochet (Esox lucius) et la carpe commune (Cyprinus carpio). Nous avons, pour chacune des trois espèces, appliqué les mêmes différences de température par rapport à leur température de référence (-4, -2, Tref, +2, +4°C) et étudié les effets sur la survie et le développement des embryons et des larves au cours de l’ensemble de la période d’alimentation endogène. Ce travail a confirmé la loi générale de l’impact de la température sur la période d’incubation (Q10 ~3). La truite commune montre une forte diminution de sa survie lors d’une augmentation de quatre degrés, néanmoins les larves survivantes sont plus grandes et ont un contenu énergétique plus important. La survie des larves de brochet augmente avec la température, ces larves sont les plus grandes et leur contenu énergétique est plus important à la température la plus élevée. La survie de la carpe n’est pas affectée par la température ; néanmoins les larves élevées à basse température sont les plus petites et présentent un faible contenu énergétique. Les résultats de survie pour les premiers stades de vie sont en concordance avec les modélisations des aires de répartition actuelle. Dans le futur, la prise en compte de la niche thermique théorique des premiers stades de vie pourrait permettre d’affiner les prévisions des aires de répartition / According to the latest report of the Intergovernmental Panel on Climate Change (IPCC), global warming is expected to continue over the next century, the average temperature could increase by 0.3 ° C to 4.8 ° C with extreme values ranging from 1 ° C to 6 ° C by 2100. These temperature changes will have direct and indirect consequences on the overall biodiversity and specifically fish which are poikilotherms. In this study three species were selected taking into account their reproductive strategy and their thermal tolerance: brown trout (Salmo trutta), pike (Esox lucius) and common carp (Cyprinus carpio). We have applied for all three species the same temperature range of from their referential temperature (-4, -2, Tref °C, +2, + 4 ° C). To carry out this study, we investigated biological traits related to survival and development during the endogenous feeding period. This work confirmed the general law of the impact of temperature during incubation phase (Q10 ~ 3). For brown trout, the results show a collapse of its population with an increase of four degrees; nevertheless surviving larvae were the longest and had a more energetic content. The survival rate of pike larvae increased when temperature increased, these larvae were the longest and the had more energetic content. The survival of the carp was not affected by temperature; nevertheless, at the lowest temperature (16°C), the larvae were smaller and had a lower energetic content. The survival results for the early stages of life are an agreement with the current distribution models. In view of this study the theoretical thermal niche species of early live stage should be undertaken to continue to refine prediction models from range

Un des moyens de développer durablement l’aquaculture européenne est la domestication d’espèces locales. Etant donné les coûts liés à la domestication d’une espèce, la mise en œuvre d’une démarche générique semble pertinente. Ainsi, l’analyse de 29 traits reproducteurs a généré une classification en 10 groupes structurés par la période de ponte et la température d’incubation des œufs. L’objet de cette thèse est de tester la pertinence de ces regroupements en étudiant l’effet d’une photophase constante longue PC et naturelle PN sur l’induction du cycle de reproduction chez des pondeurs printaniers précoces PPP (perche, sandre, gardon et brochet) et un pondeur printanier tardif PPT (rotengle). Au cours de ce travail, nous avons analysé des paramètres morpho-anatomiques, histologiques et physiologiques pour étudier les effets des traitements photopériodiques. De fortes similarités de réponse au traitement photopériodique entre les PPP ont été observées avec une inhibition du cycle de reproduction sous PC et une induction du cycle de reproduction sous PN. Si le développement gonadique et les teneurs en E2 et vitellogénine chez les femelles semblent être affectés de la même manière chez les espèces du même groupe, les teneurs en androgènes chez les deux sexes présentent des réponses espèce-spécifiques. Ceci suggère l’existence de mécanismes de régulation spécifiques qui semblent avoir peu de conséquences zootechniques. En conclusion, les similarités entre les PPP apportent des éléments de réponse sur la pertinence des regroupements surtout au niveau des paramètres les plus intégrateurs et sur la pertinence de la démarche générique qui s’appuie sur la biologie comparée / A way for the development of a sustainable inland aquaculture is the domestication of local species. As domestication usually results from a long, costly and empirical zootechnical process, the use of classifications could be a relevant strategy. In our laboratory, a generic method was developed based on grouping species sharing similar reproductive traits (29) and resulted in 10 clusters structured by spawning period and temperature of egg incubation. The aim of this work is to assess the relevance of this clustering by testing the effect of constant long (CP) and natural photoperiod (NP) on the onset of the reproductive cycle in “early spring” ESS (Eurasian perch, pikeperch, roach and pike) and a “late spring” spawner LSS (rudd). This work is based on a morpho-anatomic, histological and physiological analysis of the broodstock to study the effect of photoperiod treatments. Strong similarities were shown in the response of the ESS with inhibition of the reproductive cycle under CP and induction under NP. The gonadal development and the plasma levels of E2 and vitellogenin showed similar responses to the photoperiodic treatment between ESS, while, the androgens levels showed different responses even in species belonging to the same group and the same family. The observed similarities allow us to provide an evidence about the relevance of clusters especially for the most integrative parameters. However, even if extrapolation of current knowledge may be possible from Eurasian perch to other ESS especially for zootechnical purposes, the mechanisms of gonadogenesis regulation and especially androgenesis may be different between the studied species