Evaluation of macroalgae and amphipods as bioindicators of petroleum hydrocarbons input into the marine environment.

The brown alga Sargassum furcatum and three families of amphipods (Ampithoidae, Caprellidae and Hyalidae) associated to that algae were evaluated as bioindicators of petroleum hydrocarbons input into the marine environment of São Sebastião Channel, in southeastern region of Brazil. The n-alkanes pattern were mainly associated with the natural composition of the macroalgae and amphipods, although some indicatives of petroleum hydrocarbons such as unresolved complex mixture and the no predominance of odd over even n-alkanes have been observed in some samples. Total PAHs ranged from 33.4 to 2010 ng g-1 dry weight with the predominance of low molecular weight PAHs, mostly of naphthalene and alkyl-naphthalenes, which also suggested petroleum input. Even in low concentration, Sargassum furcatum and amphipods species studied seems to be good indicators of the introduction of petroleum hydrocarbons.

Co-occurring morphologically distinct algae support a diverse associated fauna in the intertidal zone of Araçá Bay, Brazil / Algas co-ocorrentes e morfologicamente distintas suportam uma diversa fauna associada na zona entremarés na Baía do Araçá, Brasil

Abstract Species diversity is regulated by historical, neutral and niche processes, with species tolerance, dispersal and productivity guiding diversity at larger scales, while habitat heterogeneity and biotic interactions acts in smaller scales. In rocky shores, several organisms provide secondary substrates for mobile fauna, with macroalgae being the most abundant and diverse ones. The patchiness promoted by different macroalgae hosts enhances small-scale heterogeneity and may increase and maintain the diversity of the mobile organisms, since there is a close relationship between the associated fauna and its hosts. In this study we selected three morphologically different macroalgae that coexist in the same rocky shore height in the Araçá Bay, an area under the threat of the nearby harbor expansion, and evaluated the fauna associated to each algal host. Even under similar abiotic pressure (same rocky shore height), the associated fauna of each algal host varied in number and composition, revealing a close relationship. The poorly branched foliose Ulva lactuca sustained a lower density of organisms and was dominated by isopods, while the heavily branched turf and Bostrychietum community showed a high density of organisms, with a dominance of peracarid crustaceans and annelids on the turf and more resistant groups, such as bivalves, acaris and terrestrial insects on the Bostrychietum. Previous studies in the Araçá Bay already revealed a large spatial heterogeneity in the processes and sessile organisms distribution, and here we highlight that this heterogeneity can be observed in an even smaller scale, with different algal hosts mediating the turnover of species in a scale of centimeters and meters, resulting in diversity maintenance of the associated fauna. Since the harbor expansion may prevent the occurrence of macroalgae as a result of light limitation by suspended platforms, we may expect not only a decrease in algal cover but also in the total diversity of the associated fauna in the Araçá Bay.

Resumo A diversidade de espécies é regulada por processos históricos, neutros e de nicho, com a tolerância das espécies, dispersão e produtividade do sistema guiando a diversidade em grandes escalas, enquanto a heterogeneidade do habitat e as interações bióticas atuam em escalas menores. Em costões rochosos uma série de organismos funciona como substrato secundário para a fauna móvel, sendo macroalgas o tipo mais abundante e diverso de substrato. O mosaico formado pelas diferentes macroalgas hospedeiras aumenta a heterogeneidade em pequena escala e pode aumentar e manter a diversidade dos organismos móveis, uma vez que existe uma relação próxima entre a fauna associada e seus hospedeiros. Neste estudo nós selecionamos três macroalgas diferentes morfologicamente e que coexistem na mesma altura no costão rochoso na Baía do Araçá, uma área sob a ameaça de expansão do porto que fica nas proximidades, e analisamos a fauna associada a cada alga hospedeira. Mesmo sob pressões abióticas similares (mesma altura no costão rochoso), a fauna associada a cada alga variou em número e composição, revelando de fato uma relação próxima entre fauna e alga. Ulva lactuca, uma alga foliosa com pouca ramificação, apresentou uma baixa densidade de organismos e foi dominada por isópodes, enquanto que o turf e o Bostrychietum, algas altamente ramificadas e mais complexas, apresentaram uma alta densidade de organismos, com uma dominância de crustáceos peracáridos e anelídeos no turf e grupos mais resistentes como bivalves, ácaros e insetos terrestres no Bostrychietum. Estudos anteriores conduzidos na Baía do Araçá já mostraram uma grande heterogeneidade espacial nos processos ecológicos e na distribuição dos organismos sésseis, e aqui nós ressaltamos que esta heterogeneidade pode ser observada numa escala ainda menor, com as diferentes algas mediando o turnover de espécies numa escala de centímetros a metros, resultando na manutenção da diversidade da fauna associada. Como a expansão do porto pode impedir a ocorrência das macroalgas devido à limitação de luz que será imposta pelas plataformas flutuantes, nós podemos esperar não apenas uma diminuição da cobertura de macroalgas mas também da diversidade total da fauna associada na Baía do Araçá.

Gastropoda (Mollusca) associated to Sargassum sp. beds in São Sebastião Channel - São Paulo, Brazil / Gastropoda (Mollusca) associados a bancos deSargassum sp. no Canal de São Sebastião - São Paulo, Brasil

The phytal is characterized by the formation of seaweed beds and a great diversity of associated species, the malacofauna being one of its main components. Aiming to record the species of Gastropoda associated to the brown algae Sargassum sp. C. Agardh, 1820, this study was carried out in São Sebastião Channel, northern coast of São Paulo, and nearby areas. A total of 13945 individuals were identified, belonging to 35 families and 62 species. Cerithiidae, Phasianellidae and Columbellidae were the most abundant families, represented by 34, 33 and 17% of the total collected individuals, respectively. Bittiolum varium (Pfeiffer, 1840) (Cerithiidae) and Eulithidium affine (C. B. Adams, 1850) (Phasianellidae) are the dominant species, followed by the columbelids Mitrella dichroa (G. B. Sowerby I, 1844), Anachis fenneli Radwin, 1968 and Costoanachis sertulariarium (d'Orbigny, 1839). Among the least abundant species, some of them may be considered as of fortuitous occurrences, while others seem to be typical in those habitats, although rare. The presence of juvenile specimens was recurrent, this indicating that the algae can function as a nursery for most of these species. The expressive values found, for both abundance and number of species, illustrate the great ecological importance of the phytal habitats for the gastropod species.

O fital é caracterizado pela formação de bancos de algas marinhas e uma grande diversidade de espécies associadas, estando a malacofauna entre seus principais componentes. Com o objetivo de registrar as assembleias de gastrópodes associadas è alga parda Sargassum C. Agardh, 1820, este estudo foi realizado no Canal de São Sebastião, litoral norte do estado de São Paulo, e áreas próximas. Um total de 13945 indivíduos foram identificados, pertencentes a 35 famílias e 62 espécies. Em termos de abundância, Cerithiidae, Phasianellidae e Columbellidae foram as famílias mais representativas, com 34, 33 e 17% do total de indivíduos coletados, respectivamente. Bittiolum varium (Pfeiffer, 1840) (Cerithiidae) e Eulithidium affine (C. B. Adams, 1850) (Phasianellidae) foram as espécies dominantes, seguidas pelos columbelídeos Mitrella dichroa (G. B. Sowerby I, 1844), Anachis fenneli Radwin, 1968 e Costoanachis sertulariarium (d'Orbigny, 1839). Entre as espécies pouco abundantes, algumas podem ser consideradas como de ocorrência ocasional, enquanto outras parecem ser típicas deste ambiente, porém raras. A presença de formas juvenis mostrou-se muito recorrente para a maioria das espécies, o que parece indicar que a alga pode atuar como berçário. Os valores expressivos encontrados, tanto para a abundância de indivíduos como para o número de espécies, ilustram a grande importância ecológica apresentada por este ambiente para as espécies de gastrópodes.

Sperm ultrastructure of Mytella (Bivalvia) populations from distinct habitats along the northern coast of São Paulo State, Brazil

Ultrastructural analyses of bivalve spermatozoa are relevant in studies that aim to identify taxonomic traits for the purposes of discriminating species and conducting phylogenetic studies. In the present work, spermatozoa of mussel specimens of the genus Mytella, collected from two populations living in distinct habitats, were examined by electron microscopy. The objective was to identify sperm ultrastructural taxonomic traits that could be used to differentiate Mytella species. The specimens were from populations that live in intertidal zones on the southeast coast of Brazil, either buried in muddy-sand sediment or anchored to rocky substrates. The acrosomal vesicle was conical and long, the axial rod extended from the nucleus to the acrosome, the nucleus was an oblate spheroid with a condensed chromatin, the intermediate portion contained mitochondria encircling a pair of centrioles, and there was a single flagellum. The sperm was of a primitive type. The spermatozoon ultrastructure did not distinguish the specimens buried in muddy-sand sediment from those anchored to rocky substrates. The data suggest that the specimens analyzed, despite living in distinct habitats, belong to the same species, which conchological analyses identified as M. charruana. The presence of an axial rod in their sperm cells supports the inclusion of M. charruana in the subfamily Mytilinae.

Sperm ultrastructure of Mytella (Bivalvia) populations from distinct habitats along the northern coast of São Paulo State, Brazil

Ultrastructural analyses of bivalve spermatozoa are relevant in studies that aim to identify taxonomic traits for the purposes of discriminating species and conducting phylogenetic studies. In the present work, spermatozoa of mussel specimens of the genus Mytella, collected from two populations living in distinct habitats, were examined by electron microscopy. The objective was to identify sperm ultrastructural taxonomic traits that could be used to differentiate Mytella species. The specimens were from populations that live in intertidal zones on the southeast coast of Brazil, either buried in muddy-sand sediment or anchored to rocky substrates. The acrosomal vesicle was conical and long, the axial rod extended from the nucleus to the acrosome, the nucleus was an oblate spheroid with a condensed chromatin, the intermediate portion contained mitochondria encircling a pair of centrioles, and there was a single flagellum. The sperm was of a primitive type. The spermatozoon ultrastructure did not distinguish the specimens buried in muddy-sand sediment from those anchored to rocky substrates. The data suggest that the specimens analyzed, despite living in distinct habitats, belong to the same species, which conchological analyses identified as M. charruana. The presence of an axial rod in their sperm cells supports the inclusion of M. charruana in the subfamily Mytilinae.(AU)

Sperm ultrastructure of Mytella (Bivalvia) populations from distinct habitats along the northern coast of São Paulo State, Brazil.

Ultrastructural analyses of bivalve spermatozoa are relevant in studies that aim to identify taxonomic traits for the purposes of discriminating species and conducting phylogenetic studies. In the present work, spermatozoa of mussel specimens of the genus Mytella, collected from two populations living in distinct habitats, were examined by electron microscopy. The objective was to identify sperm ultrastructural taxonomic traits that could be used to differentiate Mytella species. The specimens were from populations that live in intertidal zones on the southeast coast of Brazil, either buried in muddy-sand sediment or anchored to rocky substrates. The acrosomal vesicle was conical and long, the axial rod extended from the nucleus to the acrosome, the nucleus was an oblate spheroid with a condensed chromatin, the intermediate portion contained mitochondria encircling a pair of centrioles, and there was a single flagellum. The sperm was of a primitive type. The spermatozoon ultrastructure did not distinguish the specimens buried in muddy-sand sediment from those anchored to rocky substrates. The data suggest that the specimens analyzed, despite living in distinct habitats, belong to the same species, which conchological analyses identified as M. charruana. The presence of an axial rod in their sperm cells supports the inclusion of M. charruana in the subfamily Mytilinae.

Temporal variation in Sargassum Biomass, Hypnea epiphytism and associated fauna

Studies were carried out to investigate the temporal variation in Sargassum biomass, Hypnea epiphytism and associated fauna. There was a marked variation in the biomass of Sargassum and Hypnea among various sampling periods. Low values for Sargassum were recorded in August and November, while the lower value for Hypnea biomass was recorded in August. An inverse relationship was found between Sargassum biomass and the intensity of Hypnea epiphytism. The density of the total fauna associated to Sargassum showed a marked reduction in May. This variation was influenced by the variation patterns of the dominant faunistic groups (Gastropoda, Gammaridea, Isopoda and Caridea). Significant positive relationships were found between the biomass of Sargassum and Sargassum+Hypnea with the total density of all faunistic groups (per macroalgae biomass unit). However, the influence of Hypnea epiphytism on the phytal organisms was not evidenced