Marine and aquatic species relying on external fertilization must have special adaptation against sperm-dilution in the water. In addition mating competition may be another important source of limitation to an individual¡¦s reproductive success. If the two above mechanisms are in direct conflict, real adaptation would reflect whichever is more critical to one¡¦s fitness. In using the same logic, the unidirectional induction of spawning, i.e., females inducing males, but not males inducing females, has been reported as an evidence for the relative importance of natural selection, that is, sperm-dilution, in limiting the fitness of brittlestars in shallow waters. If the above deduction is correct, one would predict more adaptations to offset the adverse effect of sperm-dilution in various aspects of spawning-related characteristics. Two species of brittlestars. Ophiocoma dentata, living in subtidal zone, and O. scolopendrina, living in intertidal zone, were studied at Kenting, southern Taiwan. Experimental approaches were adopted to figure out if these two species have any adaptation in space and in time that can perceivably counteract the effect of sperm dilution. Spatially, the male O. dentata has the ability to search for females, and the males living with females have higher rates of responding to female spawn than unpaired males; the males do not actively search for eggs released in the water. In O. scolopendrina, neither male nor female had the ability to distinguish the sex of other individuals, they do not form pairs in nature. Males, however, have strong ability to search released eggs and then approach and spawn near the eggs. Temporally, the males of the O. scolopendrina, are sensitive to tidal rhythms in terms of inducibility by female spawns, they only spawn at the time of low tide. The possible effect of water level and photophase were both ruled out. In contrast, no such tidal rhythms of male inducibility was found in the subtidal O. dentata. Sexual selection needs not be invoked in any of the above behaviors, whereas natural selection against sperm dilution is an acceptable explanation. Last, the male O. scolopendrina displays interference behavior by blocking other males from approaching eggs are in the water. The blocked individuals are less likely to spawn.

L'état et l'évolution des écosystèmes côtiers font partie des principales préoccupations des institutions européennes. Leur fonctionnement global et leur structure sont fortement conditionnés par le comportement des premiers échelons de la chaîne alimentaire, et en particulier par les micro-algues qui se développent dans la colonne d’eau (phytoplancton) et au niveau du sédiment (microphytobenthos).Ces microalgues constituent les plus importants producteurs primaires des zones côtières (Pannard et al., 2008 ; Woelfel et al., 2010). Ils sont à la base de la chaine trophique et composent l’essentiel de la nourriture de la faune, en particulier des espèces économiquement importantes (praires, huîtres,….). Cependant, bien que le phytoplancton ait été largement étudié, le microphytobenthos est beaucoup moins connu, en particulier dans les zones subtidales. Il colonise tous les milieux (roche, vase…) dès lors qu’il y a suffisamment de lumière pour la photosynthèse (MacIntyre et al. 1996) et sa production peut égaler, voire même dépasser, la production du phytoplancton de la colonne d’eau qui le surplombe (Underwood and kromkamp, 1999). Dans cette étude, nous avons effectué un suivi hebdomadaire en Rade de Brest (55 sorties en mer en 2011), pour étudier simultanément la dynamique saisonnière du phytoplancton et du microphyto-benthos en relation avec les paramètres environnementaux.Nos résultats montrent que la dynamique du phytoplancton et du microphytobenthos dans la zone subtidale sont tout à fait différentes l’une de l'autre. Le microphytobenthos est le premier à se développer dans la saison. Il constitue un apport important d'énergie dans l'écosystème dès le début du printemps (avec 60% de la biomasse totale jusqu'en avril) et joue donc un rôle primordial dans le démarrage de l’activité biologique benthique. Le système se déplace ensuite d'un système dominé par la biomasse benthique au début du printemps, vers un système où la biomasse pélagique prend le dessus.Ces résultats mettent en évidence l’adaptation particulière du microphytobenthos aux faibles éclairements, puisqu’il est capable de produire la même biomasse que le phytoplancton de la colonne d’eau, mais avec 10 fois moins de lumière disponible. Le broutage par les hétérotrophes peut sans doute expliquer le déclin des biomasses microalgales et la différence de dynamique saisonnière après les premières floraisons. Le manque de nutriments, et en particulier les phosphates dissous dans l’eau pourrait aussi être avancé pour expliquer la chute de la biomasse microphytobenthique début d’avril, alors que le déclin du phytoplancton dans la première semaine du mois de mai coïncide à une carence en acide silicique. L’azote inorganique dissous devient ensuite potentiellement limitant dans la colonne d'eau avec des concentrations en dessous du seuil de détection, jusqu'à la fin d'octobre. D’un point de vue taxonomique, la communauté benthique est très spécifique et totalement différente de la communauté pélagique. Nous avons pu identifier 54 espèces, exclusivement des diatomées, toutes pennées, dominées par le genre Navicula. Dans la colonne d’eau, nous avons identifié 74 espèces, parmi lesquelles 51 étaient des diatomées (essentiellement centriques), dominées par Chaetoceros sp.. Le reste était partagé entre les dinoflagellés (dominé par Gymnodium sp.) et d’autres groupes fonctionnels comme les euglena, les cryptophycées, les prasinophycées, quelques rares coccolithophoridés et des petits flagellés non identifiés.Ces résultats très novateurs ouvrent de nouvelles perspectives de recherches. Il serait par exemple très intéressant de mieux comprendre les processus d’adaptation qu’ont développés les microalgues benthiques, pour être capables à des niveaux de lumière beaucoup plus faibles, d’être aussi efficace vis-à-vis de la photosynthèse que leurs homologues pélagiques. Différentes pistes sont à l’étude comme le contenu pigmentaire ou la structure de leur enveloppe siliceuse. / The most important primary producer groups of the coastal zones are suspended phytoplankton cells (Pannard et al, 2008) and microphytobenthos (MPB) (Woelfel et al., 2010). In these regions, phytoplankton and benthic microalgae are both recognized as being principal components of the diet for economically important suspension-feeding fauna (Gillespie et al., 2000). However, although phytoplankton has been vastly documented, MPB is often understudied.In sufficient light for photosynthesis they can inhabit the top few centimeters of the substrate layers (mud or sand) of marine sediment (Charpy and Charpy-Roubaud 1990, MacIntyre et al. 1996, MacIntyre and Cullen 1996) and play an important role as a food source for higher trophic levels (Revsbech et al. 1981, Sorokin 1991, Charpy and Charpy-Roubaud 1990 ). Benthic microalgal biomass mostly follows a similar distribution to the total organic matter content of surficial sediments indicating that sediment geochemical processes such as nutrient release from the breakdown of organic matter may be important in determining the distribution of MPB (Light, 1998). However, on the other hand, though not proportional with the MPB biomass, benthic production can even surpass the pelagic contribution (Underwood and kromkamp, 1999). With their ability of high primary production benthic microalgal communities can profoundly influence the flux, transformation and turnover of carbon and nutrients in coastal areas. Benthic primary producers contribute to the availability of energy and matter for benthic and pelagic food webs and define benthic and pelagic energy budgets, which affect the chemistry at the sediment-water interface, and regulate sediment stability. The shallow waters, where MPB thrives, allow a more direct interaction between pelagic and benthic processes keeping the benthos much less susceptible to physical and biochemical disturbances such as evaporation, eutrophication, and wind-forcing (Molen, 2011). Because attached microalgae can avoid advective processes and adapt to changes in light availability at short time scales, their importance is particularly enhanced (Phinney, 2004). As a result of the impact that MPB carries in a coastal ecosystem, along with the study of the functional role of MPB, investigations on their diversity have also gained some importance in the last two decades (Sundbaeck & Joensson, 1988; Blanchard, 1990; Montagna et al., 1995). Like phytoplankton, MPB communities can also act as sensitive indicators of water quality as the taxonomic composition of MPB assemblages can vary as per different nutrient levels (Lange-Bertalot, 1979; Kann, 1986). However, although the importance of MPB has been emphasized on intertidal zones (Pinckney & Zingmark, 1993; Colijn & De Jonge, 1984; Herman et al., 2000), the subtidal zones have generally been ignored till yet on this regard and as a result of which not much is known about the MPB dynamics in the subtidal zones. The subtidal zone of Bay of Brest was chosen for this study because there had been comprehensive input of nitrates to the zone in the past century .This zone has being amazingly resistant to eutrophication for quite some time, although silicate and nitrate ratio got down during the past 20 years. Research has been done previously on the spatial distribution of MPB in the zone in terms of primary productivity and biomass, but in order to achieve a more holistic view of these important photoautotrophs, a temporal study is necessary as well. The objectives of this work have been to characterize the temporal distribution of MPB in terms of biomass, productivity and biodiversity in the subtidal zone of Bay of Brest on a monthly scale, assess a comparative reasoning between MPB and the phytoplankton of the overlying water column complying on the same factors and draw an understanding on the significance of seasonal fluctuations of MPB in the overall seasonal distribution of photoautotrophs. […]

Orientadora: Profa. Dra. Natalia Pirani Ghilardi-Lopes / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Evolução e Diversidade, São Bernardo do Campo, 2018. / Apesar da importância do monitoramento das unidades de conservação (UCs) marinhas, problemas logísticos e orçamentários dificultam sua realização e, consequentemente, a gestão efetiva dessas áreas. Por isso, é necessária a busca por alternativas de baixo custo que possam auxiliar nessas questões. A abordagem por biótopos associada à ciência cidadã mostra-se adequada para o monitoramento de comunidades marinhas bentônicas por possibilitar extensa amostragem em curto período de tempo e com baixo custo, além de integrar cidadãos ativamente em produções de conhecimento. Essa pode ser uma ferramenta interessante para o monitoramento de UCs marinhas; porém, é importante que a elaboração do protocolo de monitoramento e sua validação sejam realizadas considerando-se as recomendações da literatura. Nesse sentido, este trabalho se propôs a (1) avaliar o status dos protocolos de ciência cidadã para bentos marinho e costeiro no mundo e (2) a propor, aplicar e validar o uso da ciência cidadã associada à abordagem por biótopos como uma ferramenta para o monitoramento de comunidades bentônicas em UCs marinhas. Para isso, realizamos o levantamento e comparação da estrutura de protocolos de ciência cidadã para bentos costeiro e marinho, incluindo o protocolo proposto no presente estudo. Apesar da maioria dos projetos encontrados apresentarem várias das características recomendadas pela literatura, seus principais interesses são a coleta de dados e os resultados oriundos destes, ficando a educação dos CCs, sua inclusão no processo de desenvolvimento do protocolo e sua avaliação em segundo plano. Sugerimos que os protocolos considerem a educação científica e ambiental dos CCs como um objetivo a ser atingido, e nosso protocolo leva tais ideias em consideração. Para embasar a elaboração do nosso protocolo, realizamos um levantamento prévio dos biótopos de um trecho do infralitoral consolidado da Ilha das Palmas (Estação Ecológica Tupinambás, Ubatuba/SP). Nesse levantamento, foram identificados 20 biótopos e três animais vágeis associados em apenas um mergulho. Também foram detectados organismos invasores e a dominância de tapetes na área de estudo. Isso é um demonstrativo de que a caracterização de comunidades marinhas bentônicas utilizando o método visual por biótopos pode agilizar a identificação de possíveis impactos negativos e a realização de planos de prevenção ou mitigação dos mesmos. Cientistas cidadãos (CCs) voluntários foram capacitados no uso do protocolo, que foi dividido em duas etapas: (1) a coleta de dados, que consistiu de registros fotográficos padronizados do costão rochoso; e (2) o processamento das fotografias, que consistiu da identificação (ID) dos biótopos nas fotos em um curso presencial. As fotos obtidas durante a Etapa 1 estão disponíveis na plataforma Zooniverse, através do projeto Monitore Tupinambás (https://www.zooniverse.org/projects/larissakawabe/monitore-tupinambas), no qual qualquer voluntário pode contribuir com as análises, seguindo o tutorial disponível. A avaliação educacional da pesquisa, realizada através de questionários pré e pós-atividade, mostrou principalmente que houve mudanças de percepção dos CCs em relação ao ambiente estudado. Para a validação dos dados da Etapa 2, comparamos as IDs dos biótopos realizadas pelas pesquisadoras (grupo controle) e CCs (grupo experimental), analisando a precisão e acurácia das respostas. Apesar das limitações inerentes do método utilizado (ID por foto) e das necessidades de modificação do protocolo identificadas por CCs e pesquisadoras; os resultados de acurácia e precisão foram comparáveis aos de outros trabalhos similares, demonstrando que esse protocolo, o primeiro a ser desenvolvido com foco em bentos marinho no Brasil, é uma ferramenta promissora para o monitoramento participativo e de longo prazo das UCs marinhas do país, auxiliando na gestão dessas áreas e na educação ambiental e científica dos cidadãos participantes. / Despite the importance of monitoring the marine protected areas (MPAs), logistical and budgetary problems make it difficult to carry out and, consequently, affect the effective management of these areas. Therefore, it is necessary to search for low-cost alternatives that could help with these issues. The biotope approach associated with citizen science could be interesting for the monitoring of marine benthic communities because it allows extensive sampling in a relatively short period of time and at low cost. At the same time, citizens are integrated as active contributors in the knowledge production. This can be an interesting tool for the MPA monitoring; however, it is important that the elaboration of the monitoring protocol and its validation consider the literature recommendations. In this sense, this work aimed to (1) evaluate the status of citizen science protocols for marine and coastal benthos in the world and (2) to propose, apply and validate the use of citizen science associated with the biotope approach as a tool for monitoring benthic communities in MPAs. For this, we conducted a survey and comparison of the structure of citizen science protocols for coastal and marine benthos, including the protocol proposed in the present study. Although most of the projects found present several of the characteristics recommended by the literature, their main interests are the data collection and their results, being the education of citizen scientists, their inclusion in the protocol development process and their evaluation in the background. We suggest that the protocols consider the scientific and environmental education of citizen scientists as a goal to be achieved, and our protocol takes such ideas into account. To support the elaboration of our protocol, we carried out a preliminary biotopes survey of a consolidated subtidal section of the Ilha das Palmas (Tupinambás Ecological Station, Ubatuba/SP). In this survey, 20 biotopes and three associated animals were identified in only one dive. Invasive organisms and carpet dominance were also detected in the study area. This is a demonstration that the benthic marine communities characterization using the biotope visual method can speed up the identification of possible negative impacts and the implementation of prevention or mitigation plans. Volunteer citizen scientists were trained in the use of the protocol, which was divided into two steps: (1) data collection, which consisted of standardized photographic records of the rocky reef; and (2) the processing of the photographs, which consisted of identification (ID) of the biotopes in the photos in a classroom course. The photos obtained during Stage 1 are available on the Zooniverse platform through the Monitore Tupinambás project (https://www.zooniverse.org/projects/larissakawabe/monitore-tupinambas), in which any volunteer can contribute to the analyzes, following the tutorial available. The educational evaluation of the research, performed through pre and post-activity questionnaires, showed mainly that there were changes in perception of citizen scientists in relation to the studied environment. For the data validation of Stage 2, we compared the biotope IDs performed by the researchers (control group) and citizen scientists (experimental group), analyzing their accuracy and precision. Despite the inherent limitations of the method used (ID per photo) and the identification by citizen scientists and researchers of protocol modification needs; the results of accuracy and precision were comparable to those of other similar studies, demonstrating that this protocol, the first developed with a focus on marine benthos in Brazil, is a promising tool for the participatory and long-term monitoring of the country's MPA, assisting in the management of these areas and in the environmental and scientific education of the citizens scientists.