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Increasing attention has been given marine benthic macrofauna due to its importance in marine ecosystems and for its value as bioindicator of environmental changes. One of the most abundant groups among benthic macrofauna are echinoderms which often hold keystone positions in the ecosystems and have proven to be good bioindicators. The aim of this study was to inventory echinoderms and analyze whether species diversity has change over time in Gullmarsfjorden, a fjord with limited water exchange and hence highly sensitive to environmental fluctuations. Also, what may have caused any changes and what potential effects can it have on ecosystems in the fjord, and which species may be valuable as bioindicators. The results show that species diversity of echinoderms has decreased significantly since the early 1900s and the main reduction have occured among species living on/in soft or sandy bottoms. Many of the lost echinoderms species are essential bioturbators and thus important to marine ecosystems. However, Echinocyamus pennatifidum, a sea urchin which is a valuable bioturbator may have established in the fjord during the last century judging from this study. Species like Asterias rubens and Psammechinus miliaris, which are common in the fjord, have also proved to be valuable bioindicators for abiotic changes such as increased CO2-levels and pollution of heavy metals and PCB.

A diversity of organisms is endowed with the ability to emit light; this phenomenon is called bioluminescence and occurs mainly in marine organisms. Among echinoderms, some ophiuroid species (Echinodermata, Ophiuroidea) do possess this amazing capability of light production and are used as a study model in our laboratory. The present work investigates nervous control mechanisms of light emission at different levels such as extrinsic and intrinsic controls in three ophiuroid species: Amphiura filiformis, Ophiopsila aranea and Ophiopsila californica. Results were obtained by mean of different techniques such as pharmacology, immunohistochemistry, microspectrofluorometry measurements and patch-clamp. It appears from this study that nervous control of luminescence in ophiuroids presents a high diversity at all levels (e.g. neurotransmitters, second messengers, ion channels). Two new neurotransmitters have been identified as being inductors of light production in A. filiformis (tryptamine/octopamine) and O. californica (tryptamine) but up to now, all potential transmitters tested have failed to trigger luminescence in O. aranea. Some common features have however been highlighted between the studied species as to say the Ca2+ dependence of light emission and the cAMP pathway involvement. Moreover, the hypothesis of an indirect nervous control has been suggested for the three studied species. Therefore, a model can be presented in which neurotransmitters or electrical synapses, depending on the species, could act on the relay cell which would in turn activate the luminous cell (= photocyte) and induce photogenesis.

PCBs are among the most problematic marine contaminants. Converging towards the oceans via the rivers and the atmosphere, they concentrate in sediments where they become a permanent threat to organisms living at their contact. PCBs are extremely resistant, bioaccumulated and some congeners are considered as highly toxic. The North Sea is considered as a highly contaminated area ; however little information is available regarding the impact of PCBs on key benthic organisms of this region. Ubiquist, abundant and generally recognized as a good bioindicator species, the common NE Atlantic sea star Asterias rubens (L.) is an ecosystem-structuring species in the North Sea and was chosen as an experimental model. The present study focused on the characterization of PCB bioaccumulation in A. rubens exposed through different routes (seawater, food, sediments) and on subsequent biological responses, at immune and sucellular levels. The considered responses were respectively (i) the production of reactive oxyggen species (ROS) by sea stars amoebocytes, which constitutes the main line of defence of echinoderms against pathogenic challenges and (ii) the induction of a cytochrome P450 immunopositive protein (CYP1A IPP) which, in vertebrates, is involved in PCB detoxification. Experimental exposures carried out have shown that A. rubens efficiently accumulates PCBs. Exposure concentrations were always adjusted to match those encountered in the field. PCB concentrations reached in sea stars during the experiments matched the values reported in field studies ; therefore our experimental protocol was found to accurately simulate actual field situations. Uptake kinetics were related to the planar conformation of the considered congeners : non-coplanar PCB uptake was described using saturation models, whereas coplanar PCBs (c-PCBs) were bioaccumulated according to bell-shaped kinetics. Non-coplanar congeners generally reached saturation concentrations whithin a few days or a few weeks, which means that sea stars can be used to pinpoint PCB contamination shortly after occurrence. On the other hand, c-PCB concentrations reached a peak followed by a sudden drop, indicating the probable occurrence of c-PCB-targeted metabolization processes in sea stars. Our experimental studies also demonstrated that seawater was by far the most efficient route for PCB uptake in sea stars and that even if PCB levels in seawater are extremely low compared to sediment-associated concentrations, seawater constitutes a non-negligible route for PCB uptake in marine invertebrates. Among the different body compartments, bodywall displayed the highest bioaccumulative potency and can therefore be considered as particularly interesting for field biomonitoring applications. Rectal caeca, which play a central role in digestion and excretion processes in sea stars, have also rised particular interest as results suggest these organs could be involved in the elimination of PCB 77 degradation products. The field work carried out during the present study showed that PCB concentrations measured in A. rubens tissues reflect environmental levels of certain congeners. As it was the case in experimental conditions, A. rubens differentially accumulated PCB congeners according to their planarity. Strong relationships were found between concentrations measured in sediments and those determined in sea stars body wall for certain non-coplanar congeners (e.g. 118 and 138), thus allowing to consider A. rubens as a suitable bioindicator species for medium-chlorinated PCB congeners. On the other hand, sea stars appeared to be able to regulate -to a certain extent- their content in coplanar PCBs. This implies that (i) A. rubens cannot be strictly considered as an indicator organism for c-PCBs and (ii) c-PCBs probably affect essential aspects of sea star biology, potentially leading to deleterious effects. The present study addressed effects of PCB exposure on A. rubens biology, in both experimental and field conditions. In experimental conditions, PCBs were found to significantly alter ROS production by sea stars amoebocytes. This alteration also occurred in a congener-specific way : c-PCBs were found to significantly affect, and probably impair sea stars immune system, whereas non-coplanar congeners had no effect. In the field, the PCB contribution to immunotoxicity could not be determined because none of our studies considered ROS production along with c-PCB concentration measurements. However, the levels of ROS production by sea stars amoebocytes measured in field and experimental conditions were found to potentially lead to altered immunity, and therefore to impair sea stars defence against pathogenic agents. A specially designed ELISA was used to measure CYP1A IPP in experimental and field conditions. Experimental work has shown that the induction of this protein was related to PCB exposure in a congener-specific fashion : c-PCBs alone were found to strongly induce the production of CYP1A IPP according to a dose-dependent relationship. These results have highlighted many similarities between the dioxin-like responsiveness of CYP1A IPP induction in sea stars and that occurring in vertebrates. This strongly suggests similarities in the toxicity-triggering mechanism of dioxins and c-PCBs. In the field, CYP1A IPP induction was found to be significantly related to PCB levels determined in bottom sediments. It can thus be considered as a valuable biomarker. Further research is however needed to better characterize the influence of physico-chemical and physiological parameters on CYP1A induction to refine the interpretation of the information gathered via this biomarker. Results obtained in our study have lead to questionning international regulations applying to PCB biomonitoring in the marine environment. For instance, we strongly suggest that the selection of congeners to be systematically considered should be revised to include c-PCBs. Indeed, in our experiments PCB toxicity was almost always attributable to the sole c-congeners. Historically, determination of c-PCB concentrations was extremely difficult due to analytical limitations ; however, nowadays, these problems have been overcome and do no more justify their exclusion from monitoring studies. Although A. rubens appeared to be quite resistant to PCB contamination, levels measured in sea stars from the southern North Sea can possibly affect their immune and endocrine systems in a subtle way, but with relatively low risk for this species at the short-term. However, this does not mean that other species in this region undergo similarly low risks, or that sea star-structured ecosystems may not become affected in the long-term

The uptake of CO2 by the ocean is causing major changes in its chemistry. These changes are likely to have detrimental effects on many organisms with a severe impact on calcifying species. With future OA, marine organisms will be submitted to hypercapnia (increased pCO2) and acidosis (decreased pH). Skeleton production and maintenance could be impacted due to the increased energetic cost to calcify in less favourable conditions and direct corrosive effect of undersaturated seawater resulting in dissolution of calcium-carbonate unprotected structures. Postmetamorphic echinoderms (juveniles and adults) endoskeleton is made of high magnesium-calcite, one of the most soluble form of CaCO3. Because of their low metabolism and their heavily calcified skeleton, echinoderms were designated as species particularly at risk under OA. However, the effects of OA on calcification and on skeleton maintenance vary among closely related taxa. Hypotheses explaining these contrasted tolerance to OA were stated: (1) regulation of the acid-base balance, which occurs in some echinoderms taxa and not others, plays a major role; (2) populations living in highly fluctuating habitats are adapted or selected, which may confer them a better resistance to acidified conditions. The goal of this thesis was to evaluate these hypotheses using a comparative approach in asteroids (two species) and regular euechinoids (five species). The chosen species differ by their ability to regulate their acid-base physiology and by the amplitude of fluctuations in their habitats. The impacts of OA on corrosion and mechanical properties of their skeletal elements as well as, in selected species, the expression of biomineralization-related genes were investigated. All samples were obtained from individuals exposed to acidified conditions during long-term aquarium experiments or in situ exposures (CO2 vents).Bending and compression mechanical tests analysed by Weibull statistics and expression of biomineralization-related genes appeared particularly unitive endpoints. On the contrary, occurrence of corrosion, i.e. observation in scanning electron microscopy, did not match with mechanical effects, and nanoindentation never revealed differences according to treatment. The results showed that species which were not able to regulate their acid-base physiology also presented the most affected skeleton integrity when submitted to OA. This was particularly true for the temperate sea star Asterias rubens and the Mediterranean sea urchin Arbacia lixula whose skeleton was significantly impacted. In the latter, this went together with a down-regulation of biomineralization-related genes. Temperate and tropical sea urchins that regulated their acid-base physiology (Paracentrotus lividus, Echinometra sp. B and sp. C) presented no or very limited impact of OA on their skeleton and biomineralization-related gene expression (P. lividus). The Antarctic species (the sea star Odontaster validus and the sea urchin Sterechinus neumayeri) showed no sign of acid-base physiology regulation but also no impact of acidified conditions on their skeleton. This could be linked to their particularly low metabolism or to food availability. Living in fluctuating habitats did not appear to confer a particular resistance of the skeleton in front of OA. In particular, the sea star A. rubens from Kiel Fjord, living in highly fluctuating sea water conditions, was impacted by acidified conditions they transiently encounter every year. The same was true for the temperate sea urchin A. lixula. So, it appears that sea stars and sea urchins living in fluctuating habitats might already be at the limit of their tolerance window if they do not regulate their acid-base physiology. In conclusion, it appears that the acid-base regulation may be the key biological trait to address the impact of OA on the skeleton of adult echinoderms. Studies coupling mechanical testing and analysing biomineralization-related gene expression should be extended to more taxa (within and outside echinoderms) to ascertain the relationship between OA sensitivity and absence of acid-base regulation. / Depuis la Révolution Industrielle, la concentration en dioxyde de carbone (CO2) atmosphérique augmente continuellement. Les océans absorbent en partie ce CO2, ce qui induit une diminution de la concentration en ions carbonate ainsi qu’une augmentation de la concentration en protons, processus connus sous le nom d’acidification des océans (AO). Ces changements sont susceptibles d'avoir des effets néfastes sur une variété d'organismes marins qui seront soumis à l’hypercapnie (augmentation de la pCO2) et à l’acidose (diminution du pH). De plus, la calcification fait l’objet d’une attention particulière étant donné la remontée des horizons de saturation en carbonate de calcium dans les océans. La production ainsi que le maintien du squelette pourraient être limités en raison de l'augmentation du coût énergétique de la calcification dans des conditions moins favorables. Cependant, les effets de l’AO sur la calcification et sur le maintien du squelette varient selon les taxons voire au sein d’un même taxon. Des hypothèses ont donc été émises quant aux mécanismes sous-tendant ces différences. Une meilleure résistance face à l’AO pourrait aller de pair avec (1) une capacité à réguler le pH des fluides extracellulaires, (2) une préadaptation due à l’occupation d’habitats fortement fluctuants.Les échinodermes post-métamorphiques (juvéniles et adultes), espèces marines clés, possèdent une biologie générale assez semblable et sont constitués d’un endosquelette composé de calcite hautement magnésienne, une des formes les plus solubles de carbonate de calcium. En raison de leur faible métabolisme et de leur squelette fortement calcifié, les échinodermes ont été désignés comme des espèces particulièrement vulnérables sous l’effet de l’AO. Toutefois, de récentes études montrent que le squelette de certaines espèces d’échinodermes au stade adulte n’est pas affecté lorsque les organismes sont soumis à de bas pH d’eau de mer. L'objectif principal de la présente thèse était d’évaluer les différentes hypothèses par une approche comparative chez les astéroïdes (deux espèces) et les euéchinoïdes réguliers (cinq espèces). Les espèces choisies se différencient par leur capacité à réguler leur physiologie acide-base et par l’amplitude des fluctuations de leur habitat. Les effets de l’AO sur la corrosion et les propriétés mécaniques de leurs éléments squelettiques, ainsi que, chez certaines espèces, l’expression de gènes liés à la biominéralisation ont été étudiés. Tous les échantillons ont été obtenus à partir d’individus exposés à des conditions acidifiées lors d’expériences à long terme ou d’expositions in situ (évents à CO2).Les résultats ont montré que les espèces qui n'étaient pas en mesure de réguler leur physiologie acide-base (l’étoile de mer Asterias rubens et l’oursin Arbacia lixula) présentaient également des squelettes plus affectés lorsqu'elles étaient soumises à l'AO. Les oursins tempérés et tropicaux qui régulent leur physiologie acide-base (Parancetrotus lividus, Echinometra spp.) n’ont présenté aucun impact ou un impact très limité de l’AO sur leur squelette et l’expression des gènes liés à la biominéralisation (P. lividus). Les espèces antarctiques (l’oursin Sterechinus neumayeri et l'étoile de mer Odontaster validus) n’ont montré aucun signe de régulation de la physiologie acide-base mais également aucun impact sur leur squelette dû à une diminution du pH de l'eau de mer. Cela pourrait être lié à leur métabolisme bas ou à la disponibilité de nourriture dans leur environnement. Vivre dans des habitats fluctuants ne semble pas conférer une résistance particulière du squelette face à l’AO. En particulier, l’étoile de mer A. rubens du Fjord de Kiel, qui vit dans des conditions très fluctuantes, a été affectée par des conditions d’acidification qu’elles rencontrent de manière transitoire chaque année. Il en va de même pour l’oursin tempéré A. lixula. Il semble donc que les étoiles de mer et les oursins vivant dans des habitats fluctuants pourraient déjà être à la limite de leur fenêtre de tolérance lorsqu’ils ne régulent pas leur physiologie acide-base. En conclusion, la régulation de la physiologie acide-base est une caractéristiques biologique clé pour adresser les effets de l’AO sur le squelette des échinodermes adultes. Les études couplant les tests mécaniques à l’analyse de l’expression de gènes liés à la biominéralisation devraient être étendues à plus de taxons (au sein et en dehors de échinodermes) afin de déterminer la relation entre la sensibilité de la calcification face à l’AO et l’absence de régulation acide-base. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

This diploma thesis presents the first study focused on the ontogenetic development of eocrinoid echinoderms in the Czech Republic. Parsley's work (2012) on ontogeny of the genus Gogia from south China is the model study. The aim of this thesis is a comparable study of ontogeny of eocrinoid echinoderms from Cambrian of the Barrandian area. Akadocrinus jani Prokop, 1962 was studied. Using detailed morphological description and measurement of various parameters, three different ontogenetic stages have been established: juvenile ontogenetic stage, mature ontogenetic stage and gerontic ontogenetic stage. Thecal height is the deciding factor for the determination of the specific ontogenetic stage. Further, during ontogeny of this species some trends in changes in the size of body parts are observed (e.g., changes in the diameter of thecal plates). In-depth study of morphological details showed that the originally distinguished two species, Akadocrinus jani Prokop, 1962 and Akadocrinus nuncius Prokop, 1962, represent one species only. Keywords: eocrinoid echinoderms, Akadocrinus jani, ontogeny.

Desde a revisão taxonômica dos Ophidiasteridae por H. L. Clark (1921), em que 20 gêneros foram reconhecidos como válidos, vários novos gêneros e espécies foram incluídos nesta família, e os limites entre alguns deles se tornaram largamente arbitrários. Isso também se aplica a Narcissia Gray, 1840, cuja morfologia e taxonomia são, ainda hoje, muito malcompreendidas. Os principais objetivos desta pesquisa foram: revisar a taxonomia do gênero Narcissia ao longo de toda a sua área de distribuição, a partir de estudos morfológicos; redescrever e caracterizar, morfologicamente, Narcissia trigonaria Sladen, 1889 strictu senso; caracterizar, morfologicamente, N. canariensis (d\'Orbigny, 1839) e N. ahearnae Pawson, 2007, as duas espécies válidas mais semelhantes a N. trigonaria; rever a validade de N. trigonaria helenaeMortensen, 1933; rever a validade de N. gracilis malpeloensis Downey, 1975. Cercade 370 espécimes do gênero Narcissia foram analisados: dois indivíduos de N. ahearnae, 82 espécimes de N. canariensis, 44 de N. gracilis e 242 de N. trigonaria. O material que serviu de base para nossos estudos pertence às coleções de museus nacionais e estrangeiras. Aterminologia para estruturas morfológicas seguiu Clark (1921), Turner & Dearborn (1972),Clark e Downey (1992) e Gale (2011). As pedicelárias foram classificadas de acordo com Jangoux e Lambert (1988). Todas as estruturas morfológicas de importância taxonômica foram ilustradas. E, pela primeira vez, os caracteres internos deste grupo foram estudados, a partir de microscopia eletrônica e tomografia. Uma nova diagnose para o gênero Narcissia foi disponibilizada. Todas as espécies do gênero foram revisadas e morfologicamente redescritas. Narcissia trigonaria, descrita a partir de um juvenil, foi redescrita a partir de um exemplar adulto, proveniente da localidade tipo (Bahia). Narcissia ahearnae é considerada uma espécie válida, e N. canariensis e N. trigonaria entidades distintas. Narcissia trigonaria helenae foi colocada na sinonímia de N. trigonaria, e N. gracilis malpeloensis entrou para a sinonímia de N. gracilis. A classificação de Narcissia, dentro da Família Ophidiasteridae, foi contestada, a partir de caracteres morfológicos. Os dados obtidos neste trabalho são, de longe, os mais completos já adquiridos para o gênero Narcissia e, futuramente, podem servir de base para os estudos morfológicos de outros grupos da Classe Asteroidea. / Since the taxonomic revision of the Ophidiasteridae by H. L. Clark (1921), in which 20 genera were recognized as valid, several new genera and species were included in this family, and the boundaries between some of them became largely arbitrary. This also applies to Narcissia Gray,1840, whose morphology and taxonomy are still very poorly understood today. The main goals of this research were: review the taxonomy of the genus Narcissia, throughout its range of distribution, from morphological studies; redescribe and characterize, morphologically, N. trigonaria Sladen, 1889 str. s; characterize, morphologically, N. canariensis (d\'Orbigny, 1839) and N. ahearnae Pawson, 2007, the two valid species most similar to N. trigonaria; review the validity of N. trigonaria var. helenaeMortensen, 1933; review the validity of the N. gracilismalpeloensis Downey, 1975. About 370 specimens of the genus Narcissia were analyzed: two individuals of N. ahearnae, 82 specimens of N. canariensis, 44 of N. gracilis, and 242 of N. trigonaria. The material that has served as a basis for our studies belongs to the national and foreign collections. The terminology for morphological structures has followed Clark (1921), Turner & Dearborn (1972), Clark & Downey (1992) and Gale (2011). Pedicellariae were classified according to Jangoux & Lambert (1988). All morphological structures of taxonomic importance have been illustrated. And, for the first time, the internal characters of this group were studied, from electron microscopy and tomography. A new diagnosis for the genus Narcissia was constructed. All species of the genus were reviewed and morphologically redescribed. Narcissia trigonaria, described from a juvenile, was redescribed from an adult specimen, from the type locality (Bahia). Narcissia ahearnae is considered a valid species, and N. canariensis and N. trigonaria distinct entities. Narcissia trigonaria helenaewas placed in the synonymy of N. trigonaria, and N. gracilis malpeloensis into the synonymy of N. gracilis.The classification of Narcissia, within the Family Ophidiasteridae, was contested, frommorphological characters. The data set obtained in this work are, by far, the most complete already acquired within the genus Narcissia and, in the future, may serve as the basis for the morphological studies of other groups of the Asteroidea Class.

Well-preserved echinoderm faunas are rare in the fossil record, and when uncovered, understanding their occurrence can be useful in interpreting other faunas. In this study, two such faunas of the same age from separate localities in the shallow-marine Ramey Creek Member of the Slade Formation in the Upper Mississippian (Chesterian) rocks of eastern Kentucky are examined. Of the more than 5,000 fossil specimens from both localities, only 9–34 percent were echinoderms from 3–5 classes. Nine non-echinoderm (8 invertebrate and one vertebrate) classes occurred at both localities, but of these, bryozoans, brachiopods and sponges dominated. To understand the attributes of both localities (Valley Stone and 213 quarries), the geologic and structural settings, lithofacies and depositional environments, as well as faunal makeup and abundances (diversity, evenness, density), were compared and contrasted. Faunas from the Valley Stone Quarry were located on an uplifted fault block in more shallow, open-marine waters with higher energies. As indicated by four distinct lithofacies, the depositional setting was more extensive and varied with interspersed shoals and basins that could accommodate a greater richness (65 species), even though organism densities and abundance were less. In contrast, fauna from the 213 Quarry were located on a downdropped fault block in a more localized, deeper, storm-shelf setting, characterized by a single lithofacies. Although organism density and abundance were nearly twice as high as that at the Valley Stone Quarry, species richness was lower (45 species), and only one species, a bryozoan, predominated. Overall, echinoderm classes, species and individuals were more abundant at the Valley Stone Quarry, and I suggest that this is related to the shallower and more varied depositional environments that developed in response to presence on the shallow, uplifted fault block. This suggests the importance of regional features like faults in controlling environments and organism distribution through time. Although the faunas were originally collected for their echinoderm-dominated “crinoid gardens,” in fact, echinoderms were in the minority, and bryozoans and brachiopods predominated in the communities. Hence, the communities might better be described as bryozoan “thickets” and brachiopod “pavements.”