Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Ecology and Evolution." Includes bibliographical references (p. 130-143).

Orientador: Shirlei Maria Recco Pimentel / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-04T04:12:07Z (GMT). No. of bitstreams: 1 Introini_GiseleOrlandi_M.pdf: 3314388 bytes, checksum: bf79294ca706599f733d1e5bf15dca35 (MD5) Previous issue date: 2005 / Resumo: Numerosos estudos têm demonstrado a relevância da morfologia dos espermatozóides para determinação da filogenia no filo Mollusca. Adicionalmente, o estudo da morfologia e do número de cromossomos tem correspondido a uma eficiente ferramenta para a identificação de espécies, de híbridos e, menos usualmente, de populações. O presente trabalho analisou a ultra-estrutura dos espermatozóides de duas espécies do gênero Brachidontes e uma espécie do gênero Isognomon. As espécies B. darwinianus e I. bicolor foram também estudadas citogeneticamente. Moluscos pertencentes ao gênero Brachidontes vivem na zona entre marés de enseadas e baías e se fixam pelo bisso ao substrato rochoso, formando aglomerados de centenas de indivíduos. Brachidontes solisianus encontra-se distribuído da Costa Atlântica do México até o Uruguai e B. darwinianus é encontrado do Rio de Janeiro a Patagônia. Na costa do Estado de São Paulo, populações dessas duas espécies que exibem caracteres conquiológicos muito semelhantes, compartilham áreas em comum. A utilização da forma da concha como característica para separar mitilídeos é questionável, pois suas conchas, por possuírem grande plasticidade, podem apresentar variações morfológicas devido às influências ambientais. A espécie I. bico/ar é encontrada no litoral brasileiro com distribuição do Rio Grande do Norte até Santa Catarina. O extremo norte da distribuição da espécie é Bermudas, com ocorrência pelo litoral da Flórida, Golfo do México e Caribe. Acredita-se que I. bico/ar tenha sido sistematicamente, e de longa data, confundido com I. a/atus. A grande similaridade nas características externas da concha de I. a/atus e I. bico/ar, a variabilidade intra-específica na forma de ambas espécies, mais o fato de terem hábitos e habitats semelhantes, podem conduzir a equívocos de identificação. Os espécimes ocorrem desde o supralitoral até sete metros de profundidade no infralitoral. Os espermatozóides de B. darwinianus, B. solisianus e I. bic%r, como aqueles produzidos por muitas espécies de bivalves, apresentam uma morfologia típica de animais marinhos que lançam seus gametas fertilizando seus ovos na água do mar. Os gametas masculinos de B. darwinianus, de B. so/isianus e de /. bico/ar contém: acrossomo conspícuo (cônico e alongado em Brachidontes e arredondado em /sognomon); núcleo esferiforme condensado; um par de centríolos e 4-5 mitocôndrias situadas na peça intermediária e um axonema portador de 9 pares de microtúbulos ao redor de um par central. A estrutura geral do espermatozóide de Brachidontes é bastante semelhante a de outras espécies da mesma sub-família e parece agrupar esse gênero adequadamente na classificação atualmente aceita, ou seja, sub-família Modiolinae. A única característica que permite distinguir o espermatozóide destas duas espécies é o comprimento do acrossomo. A presença de um prolongamento acrossomal em B. solisianus pode significar um aumento da eficiência reprodutiva e deste modo contribuir para a maior distribuição geográfica desta espécie. Em relação a ultraestrutura do espermatozóide de /. bico/ar, estudos sobre a biologia da fertilização desta espécie são necessários para melhor compreender o significado biológico da presença de um filamento axial no espaço subacrossomal e de grânulos de glicogênio na peça intermediária. Considerando o fato de que esta espécie apresenta ampla distribuição geográfica e que tem se tomado uma espécie invasora em muitas regiões, especialmente no Brasil, seria interessante, verificar se estas características morfológicas do espermatozóide são capazes de proporcionar aumento na eficiência reprodutiva. A análise citogenética revelou a presença de 2n = 30 cromossomos para B. darwinianus e 2n = 28 cromossomos para J. bico/ar. Os resultados obtidos foram comparados com cariótipos de outros bivalves. Os números encontrados são comuns dentro da família Mytilidae e super-família Pteriacea, respectivamente, deste modo, estas espécies estão adequadamente classificadas, de acordo com os caracteres cromossômicos estudados / Abstract: Although bivalve species are well known anatomically, the taxonomic relationships among many of the species in this class are controversial. Numerous investigations have demonstrated the usefulness of sperm morphology in evaluating molluscan phylogeny. In this work, we used transmission and scanning electron microscopy to study the structure of mature spermatozoa from three bivalves, Brachidontes darwinianus, Brachidontes solisianus and Isognomon bicolor from the southeastern Brazilian coast, and compared them with those of other bivalves, particularly other members of the sub-class Pteriomorphia. The Giemsa-stained karyotypes of B. darwinianus and I. bicolor were also determined and compared with those of other bivalves. The genus Brachidontes has a wide geographic distribution and is particularly abundant in the intertidal zone of many rocky shores along the Brazilian coast, often in areas with strong water currents. Brachidontes darwinianus occurs from the state of Rio de Janeiro, Brazil, to Patagonia, in Argentina, whereas B- solisianus is distributed from Mexico to Uruguay. The spermatozoa of both species were of the primitive or ect-aquasperm type. In both species, the spermatozoan head contained a spheroidal nucleus capped by a conical acrosome with an anterior extension. No actin was detected in the subacrosomal region. However, immunocytochemical staining identified actin throughout the sperm nucleus of both species. The chromatin was highly electrondense, homogenous and compact, and the nuclei contained randomly distributed, electron-Iucent regions formed by invaginations of the nuclear envelope. These invaginations were detected by E-PT A staining for glycoproteins at low pH. The midpiece region consisted of five spherical mitochondria grouped in a ring around a pair of short cylindrical centrioles. The flagellum exhibited the typical 9+2 microtubule structure (nine double outer tubules + two single central tubules). The only marked difference in the morphology of spermatozoa from these two species was the longer anterior extension of the acrosomal vesicle in B. solisianus. This elongated acrosome may facilitate penetration of the jelly coat and cytoplasm of large oocytes and could increase the efficiency of fertilization. The resulting enhanced reproductive success could account for the wider geographic distribution of B. solisianus. Isognomon bicolor is distributed throughout many countries in the Americas. This species has an epifaunal existence and is usually found attached by its byssus to jetty pilings or growing in crevices on rocky shores exposed to strong water currents. The spermatozoa of this species were of the primitive or ectaquasperm type. The sperm head consisted of a round-to-oval, electron-dense nucleus (with an anterior fossa) capped by a small acrosome that contained an outer electron-dense and inner electron-Iucent region. The subacrosomal region had a thin filament that could play an important role in fertilization. Immunocytochemical analysis revealed the presence of actin throughout the nucleus of I. bicolor sperm, but no actin was detected in the subacrosomal area. Hence, the chemical nature of the amorphous material and of the tenuous filament present in the subacrosomal area remains unknown. The midpiece contained four ar five spherical mitochondria surrounding the centriole apparatus. Depasits of electron-dense granules, considered to be perimitochondrial glycogen, were observed around the centrioles and mitochondria. The flagellum had the typical 9+2 microtubular pattern. Ali of the B. darwinianus specimens studied had a diploid number of 2n=30 chromosomes whereas those of I. bico/ar had a diploid number af 2n=28. This chromosomal number is relatively common among closely related species of Brachidontes and Isognomon / Mestrado / Biologia Celular / Mestre em Biologia Celular e Estrutural

El mejillín, Brachidontes rodriguezii, es un bivalvo intermareal de la familia Mytilidae que se distribuye a lo largo de la costa Atlántica Sudamericana (29°- 46° Lat Sur). Es la especie dominante en los intermareales rocosos bonaerenses y norpatagónicos (Argentina). Este trabajo tuvo por finalidad analizar la distribución espacial y temporal y la dinámica poblacional de B. rodriguezii en el intermareal rocoso de Pehuén Co (Provincia de Buenos Aires), explorar las relaciones de densodependencia y capacidad de carga del ambiente y evaluar el efecto del enterramiento debido a la dinámica sedimentaria costera. Además, se describió la comunidad asociada al ambiente formado por el mejillín (denominado mejillinar), explorando las relaciones entre los descriptores comunitarios (diversidad, riqueza específica y uniformidad) y las variables ambientales (temperatura del agua, salinidad, altura y período de olas, granulometría y materia orgánica de los sedimentos). Durante dos años se realizaron muestreos estacionales, utilizando parcelas de 200 cm2 , sobre las superficies horizontales y verticales de una plataforma rocosa de abrasión intermareal a la cual se le registró periódicamente las variaciones de la superficie enterrada y desenterrada por arenas de la playa. El mejillinar de Pehuén Co presentó en general menores densidades de B. rodriguezii con respecto a otros mejillinares ubicados en el centro geográfico de distribución de la especie, así como una tendencia de empobrecimiento de la diversidad de la comunidad asociada, la cual estuvo dominada por el mitílido y constituida por taxones con un modo de vida predominantemente móvil e infaunal. Localmente las mayores densidades poblacionales del mejillín se registraron sobre las superficies verticales de la plataforma de abrasión estudiada, debido a su disposición en estratos, estrategia que le permitió disminuir la competencia intraespecífica. En las superficies horizontales, la población se dispuso en un solo estrato, evidenciándose los efectos de auto-raleo debidos a la limitación del espacio. La población de B. rodriguezii en Pehuén Co presentó una estructura de talla trimodal. El reclutamiento se registró durante todo el año con máximos durante el otoño y la primavera, como ha sido reportado para otros mejillinares bonaerenses. Las variaciones del estado morfodinámico de la playa arenosa provocaron efectos sobre la granulometría de los sedimentos retenidos por la matriz orgánica del mejillinar. Durante el período de acreción aumentó la proporción de arenas finas dentro de la matriz, mientras que en la fase erosiva de la playa se observó un aumento de la proporción de granos gruesos. Por otra parte, el enterramiento de las rocas y las grandes cantidades de arenas acumuladas sobre superficies horizontales disminuyeron la capacidad de carga del afloramiento y particularmente de dicha superficie. Los eventos de enterramientos del mejillinar provocaron mortalidades masivas de B. rodriguezii por sofocación, lo cual disminuyó su dominancia y se asoció con aumentos de la diversidad y de la uniformidad de la comunidad cuando la intensidad del disturbio fue intermedia (disturbio asociado con las muestras de los sedimentos por debajo de la matriz), en tanto que disturbios severos de enterramiento (disturbio máximo) provocaron la disminución del número de taxones de la comunidad del mejillinar. / The mussel Brachidontes rodriguezii (mejillín) is an intertidal bivalve of the Mytilidae family that is distributed along the South American Atlantic coast (29 ° - 46 ° South Lat). It is the dominant species in the rocky intertidal areas of Buenos Aires and North Patagonia (Argentina). The purpose of this work were to analyze the spatial and temporal distribution and the population dynamics of B. rodriguezii in the intertidal of Pehuén Co (Buenos Aires Province), to explore the relationships of density and carrying capacity of the environment and to evaluate the effect of burial due to the processes of coastal sedimentary dynamics. In addition, the community associated with the environment formed by the mejillín (called mejillinar) was described, exploring the relationships between community descriptors (diversity, specific richness and uniformity) and environmental variables (water temperature, salinity, wave height and period, sediment granulometry and organic matter). Seasonal samplings were carried out for two years, using plots of 200 cm2 , on the horizontal and vertical surfaces of an intertidal rocky outcrop to which the variations of the surface exposed and covered by beach sand were recorded periodically. The Pehuén Co mussel bed generally presented lower B. rodriguezii densities with respect to other mussel beds located in the geographic center of distribution of the species, as well as a trend of impoverishment of the diversity of the associated community, which was dominated by the mytilid and made up of taxa with a way of life with a predominance of mobile infauna. Locally, the highest population densities of mussels were recorded on the vertical surfaces of the outcrop studied, due to their layered arrangement, a strategy that allowed them to reduce intraspecific competition. On the horizontal surfaces, the population was arranged in a single layer, evidencing the effects of self-thinning due to the limitation of space. The population of B. rodriguezii in Pehuén Co presented a trimodal size structure. Recruitment was recorded throughout the year with maximums during autumn and spring, as has been reported for other mussel beds in Buenos Aires. Variations in the morphodynamic state of the sandy beach caused effects on the granulometry of the sediments retained by the organic matrix of the mussel. During the accretion period, the proportion of fine sands within the matrix increased, while in the erosive phase of the beach an increase in the proportion of coarse grains was observed. On the other hand, the burial of the rocks and the large amounts of accumulated sands on horizontal surfaces decreased the loading capacity of the outcrop and particularly of said surface. The mussel bed burial events caused massive mortalities of B. rodriguezii by suffocation, which decreased its dominance and was associated with increases in community diversity and uniformity when the intensity of the disturbance was intermediate (disturbance associated with samples of sediments below the matrix), while severe burial disturbances (maximum disturbance) caused the decrease in the number of taxons in the mejillinar community.

Orientadores: Luiz Francisco Lembo Duarte, Vera Nisaka Solferini / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-15T12:02:47Z (GMT). No. of bitstreams: 1 Aranha_TiagoPorto_M.pdf: 851406 bytes, checksum: 8a0e698a85700d7b59721c4e8167d63f (MD5) Previous issue date: 2010 / Resumo: A quantidade de espécies envolvidas, a amplitude geográfica e a freqüência de ocorrência das invasões biológicas não conhecem precedentes. Atualmente as invasões são consideradas um processo composto de múltiplos estágios, dinâmico no espaço e no tempo. As populações invasoras podem estacionar em determinados estágios e até regredir a estágios anteriores antes de atingir a fase de clímax. As invasões são consideradas uma das grandes causas da extinção de espécies no planeta, desta forma, a compreensão dos mecanismos e fatores que influenciam o sucesso das invasões e o entendimento de seus efeitos em comunidades nativas é fundamental. O objeto de estudo do presente trabalho é o bivalve invasor Isognomon bicolor em costões rochosos do sudeste do Brasil. No capítulo I, padrões de distribuição e dominância de populações localizadas no litoral norte de São Paulo foram documentados. A situação atual da invasão de I. bicolor foi avaliada frente às populações de organismos nativos da área. No capítulo II, padrões de variabilidade e estruturação genética de populações de I. bicolor no litoral sudeste foram descritos e comparados com aqueles para populações do bivalve nativo Brachidontes solisianus. A combinação dessas duas abordagens permitiu uma maior compreensão do processo de invasão de I. bicolor e das conseqüências dessa invasão sobre as espécies nativas. Atualmente I. bicolor apresenta-se amplamente distribuído no litoral norte de São Paulo, entretanto, ao contrário de estudos anteriores, suas populações apresentam baixas porcentagens de cobertura nos costões onde ocorre. Tal fato deve-se a um evento de mortaliade em massa pelo qual a espécie passou recentemente. A alta variabilidade e baixa estruturação genética observada, semelhante à encontrada para o bivalve nativo B. solisianus, são indícios de um processo de invasão costituido por múltiplos episódios de introdução e da grande capacidade de dispersão do invasor. Esses resultados são preocupantes pois sugerem que as populações de I. bicolor estão relativamente estáveis e conectadas entre si, tornando sua exitinção na costa sudeste do Brasil improvável, mesmo após a ocorrência do evento de mortalidade em massa / Abstract: The species number, geographic scale and frequency of biological invasions are unparalleled. Currently, invasions are considered as a several stages process, dynamic in space and time. The invasive populations can remain at some stage or return to earlier stages before reaching the invasion climax. Invasions are considered one of the major causes of species extinction on the planet and thus. Understanding mechanisms and factors that influence invasion success and its effects on native communities is of primary imporatance. The present work studied the invasive Isognomon bicolor populations along the southeastern coast of Brazil. In Chapter I, the distribution and the dominance patterns of I. bicolor were documented along the northern coast of São Paulo. The population attributes of the invasive species I. bicolor were evaluated and compared to the population attributes of native organisms in the sampled area. In Chapter II, the genetic variability and the structure patterns of four I. bicolor populations on southeastern Brazilian Coast were analyzed and compared with those of the native Brachidontes solisianus populations. The combination of these two approaches has enabled a better understanding of I. bicolor invasion process and its consequences for native species. Currently, I. bicolor has become widely distributed in the northern coast of São Paulo, however, unlike previous studies, I.bicolor is not dominant in the rocky shores. This fact may be caused by a recent mass mortality event. The high variability and low genetic structure observed, similar to the genetic attibutes of the native bivalve B. solisianus populations, are evidences of an invasion process with multiple introduction events and of the large invader dispersal ability. These results are concerning as they suggest that I.bicolor populations are relatively stable and connected to each other, making its extinction in the southeastern coast of Brazil unlikely, even after the occurrence of a mass mortality event / Mestrado / Ecologia / Mestre em Ecologia

The St Lucia estuarine system, Africa’s largest estuarine lake, is characterised by cyclic changes from hypersaline to oligo/mesohaline conditions in response to alternations between drought and wetter than average years. In addition, St Lucia also experiences stochastic disturbances, such as flooding events that rapidly decrease salinity levels. Due to their sessile and slow moving nature, bivalves are particularly vulnerable to rapid or prolonged changes in the physico-chemical environment. The recent freshwater deprivation crisis that prevailed for the last decade resulted in a significant loss in bivalve species richness within the system. An annotated and illustrated bivalve census revealed the occurrence of twenty-four species within St Lucia between the years 1925 and 2011. However, only six species were recorded during the most recent survey in March 2011. The infaunal razor clam, Solen cylindraceus, and the epifaunal brackwater mussel, Brachidontes virgiliae, are currently the dominant bivalve species within St Lucia. This study, therefore, aimed to record the species richness of bivalves found in Lake St Lucia and to investigate key biological aspects of the two dominant bivalve taxa within the system, under different salinity regimes. Experiments revealed that S. cylindraceus can tolerate salinities between 15 and 65, while B. virgiliae prefers salinity levels ranging from freshwater to 20. The varying tolerance limits, therefore, dictate the distribution of these species during different climatic conditions within the estuarine lake. During wet periods, S. cylindraceus is restricted to the northern reaches, unable to tolerate the oligohaline conditions present in the rest of the system. Conversely, B. virgiliae, often restricted to the Narrows, becomes ubiquitous throughout the system under such conditions. Solen cylindraceus can reach a maximum length of 95 mm. However, in the St Lucia estuarine system, specimens seldom exceed a length of 55 mm, probably because prevailing/re-occurring harsh conditions prevent them from reaching maximum size. In situ measurements of this species also revealed less growth during the first year of life than for the same species in different systems. While B. virgiliae is substantially smaller than S. cylindraceus, the high densities that this species is able to attain makes it an important grazer with the potential to have significant feeding impacts on the local phytoplankton biomass. Results showed that in localised areas, B. virgiliae populations may consume up to eight times the available phytoplankton biomass. These key bivalve species are strongly influenced by the fluctuation in climatic conditions from wet to dry phases. Thus, understanding the effects that climatic shifts have on key estuarine species is essential, as flood and drought events are predicted to increase in frequency, intensity and duration as a result of global climate change. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2014.

Ce projet de recherche porte sur l’étude de la contamination de la côte libanaise par les composés organiques (HAP, DDE) et par les éléments-trace métalliques (Hg, Pb principalement). Les travaux sur les compartiments sédimentaires et biologiques de la côte libanaise constituent deux parties aux problématiques et aux approches distinctes autour desquelles s’articule cette thèse. Dans la première partie, l’analyse d’une carotte sédimentaire datée prélevée sur le plateau continental du Sud du Liban a permis de reconstituer l’historique de contamination dans le bassin Levantin. Les analyses de contaminants dans les sédiments de la carotte C1 combinés à la datation aux 210Pb et 137Cs ont permis d’obtenir un enregistrement fiable des variations du dépôt de mercure, de plomb et de HAP sur le plateau continental libanais, dans le bassin Levantin. Bien que les concentrations et les flux soient relativement faibles, une augmentation en deux phases des concentrations est bien mise en évidence par le profil sédimentaire de C1. Le charbon est identifié comme source principale de Pb, de Hg et de HAP dans le bassin Levantin entre la moitié du 19ème siècle et la moitié du 20ème siècle. Les résultats des ratios isotopiques du Pb et des ratios diagnostiques de HAP appuient ce constat. Les archives sédimentaires dans la carotte C1 fournissent un signal du dépôt de contaminants à l’échelle globale probablement lié aux sources d’émissions atmosphériques en provenance d’Europe Centrale et de l’Est. Dans la seconde partie, une étude de la contamination par les HAP du littoral libanais est menée suite à la marée noire résultant du conflit armé israélo-libanais en 2006. Une approche de biomonitoring sur trois ans utilisant l’espèce de moules invasives Brachidontes variabilis a été développée. Les résultats indiquent une décroissance progressive des concentrations de HAP dans l’écosystème intertidal du littoral libanais. La contamination par les HAP du fioul en zone subtidale en 2007 est nettement plus faible. Cependant la signature des HAP dans les tissus de moules prélevées trois ans après la marée noire indique toujours la présence des composés du fioul de Jiyeh. La contamination est particulièrement persistante dans certaines zones fortement touchées par la nappe de fioul en 2006. Il apparaît que l’état initial pré-marée noire n’a pas été atteint, même trois ans après la marée noire de Jiyeh. L’examen détaillé de l’évolution spatiale et temporelle de la contamination par les HAP de l’environnement intertidal est présenté dans ce volet de notre étude. / This research project aims at the study of the contamination of the Lebanese coast by PAHs, DDE, Hg and Pb. The research work is divided into two distinct parts concerning two environmental compartments (sedimentary and biological) and it addresses different questions and approaches. In the first part, the study of a dated sediment core raised from the continental shelf in southern Lebanese coast allowed reconstructing the contamination history in the Levantine basin. The contaminants’ analysis as well as 210Pb and 137Cs datation allowed obtaining a reliable record of mercury, lead and PAHs sedimentary deposition in the Lebanese continental margin in the Levantine basin. Although concentrations and fluxes are relatively low, a two-phase increase of concentration is found using C1 core sedimentary profiles. Coal was identified as the main source of Pb, Hg and PAHs in the Levantine basin between the mid 19th and the mid 20th century. Ratios of Pb stable isotopes and PAH diagnostic ratios support this assumption. The studied sedimentary archives provide also information on the deposition of contaminants on a global scale possibly related to atmospheric emissions mainly from Central and Eastern Europe. In the second part of the thesis, the study of contamination by PAHs of the Lebanese coast was undertaken following an oil spill in the south of Lebanon, which occurred after the bombardment by the Israeli military of the electric power plant in Jiyeh in 2006. We have set-up a biomonitoring program with an invasive mussel specie Brachidontes variabilis over a three-year study. Results indicate a progressive decrease of PAH concentrations in the intertidal ecosystem of the Lebanese coast. Contamination of the subtidal zone in 2007 by Jiyeh fuel oil was significantly lower. However, Jiyeh fuel oil signature was still detectable in mussel tissues even three years after the oil spill. Contamination was found to be particularly persistent in some of the highly oiled sites. It appears that pre-spill state was still not reached even three years following the oil spill. Detailed investigation of spatio-temporal changes of intertidal mussels contamination by PAH is also presented in this part of the thesis.