Sonia Maria Barreto Pereira

Coastal urbanization leads to remarkable seaweed species loss and community shifts along the SW Atlantic

Coastal urbanization is rapidly expanding worldwide while its impacts on seaweed communities remain poorly understood. We assessed the impact of urbanization along an extensive latitudinal gradient encompassing three phycogeographical regions in the SW Atlantic. Human population density, number of dwellings, and terrestrial vegetation cover were determined for each survey area and correlated with diversity indices calculated from seaweed percent cover data. Urban areas had significantly lower calcareous algal cover (-38%), and there was significantly less carbonate in the sediment off urban areas than off reference areas. Seaweed richness averaged 26% less in urban areas than in areas with higher vegetation cover. We observed a remarkable decline in Phaeophyceae and a substantial increase of Chlorophyta in urban areas across a wide latitudinal gradient. Our data show that coastal urbanization is causing substantial loss of seaweed biodiversity in the SW Atlantic, and is considerably changing seaweed assemblages.

The impact of coastal urbanization on the structure of phytobenthic communities in southern Brazil

The anthropogenic pressures on coastal areas represent important factors affecting local, regional, and even global patterns of distribution and abundance of benthic organisms. This report undertakes a comparative analysis of the community structure of rocky shore intertidal phytobenthos in both pristine like environments (PLE) and urbanized environments (UBE) in southern Brazil, characterizing variations on different spatial scales. Multivariate analysis of variance indicated that the PLE is characterized by a larger number of taxa and an increased occurrence of Rhodophyta species in relation to UBE. In contrast, UBE were dominated by opportunistic algae, such as Cladophora and Ulva spp. Significance tests further indicated higher species richness and Shannon-Wiener diversity on the PLE in relation to UBE. Here we provide data showing the magnitude of seaweed biodiversity loss and discuss direct and indirect consequences of unplanned urbanization on these communities.

Phylogenetic analysis of Codium species from Brazil, with the description of the new species C. pernambucensis (Bryopsidales, Chlorophyta)

The genus Codium comprises c. 125 species widely distributed in marine coastal environments throughout the world. Due to morphological plasticity, the taxonomic delimitation of Codium species can be difficult. Sequences of the first exon of the large subunit of RUBISCO (rbcL) have been used in the molecular delimitation of species and for phylogenetic purposes. In the present study, we complement previous morphological work on Brazilian Codium species with molecular systematics. Based on the partial rbcL sequences, seven species are recognized along the Brazilian coast: C. decorticatum, C. intertextum, C. isthmocladum, C. profundum, C. spongiosum, C. taylorii and the new species Codium pernambucensis. Ten unique sequences were obtained among the samples examined, which we used in combination with previously published sequences to infer molecular phylogenies using various methods. The resulting trees showed three principal monophyletic groupings: Clade A with species having a prostrate habit, not branched, and mostly with small, grouped utricles; Clade B primarily consisting of upright species with cylindrical branches and large individual utricles; and Clade C composed of upright species with cylindrical branches that are slightly flattened, and have intermediate-sized individual utricles. The Brazilian species grouped with morphologically similar taxa from other geographic localities, and are present in all three main clades. A new sprawling species, Codium pernambucensis is described based on morphology and molecular analyses.

Clorofíceas marinhas bentônicas da Praia de Serrambi, Pernambuco, Brasil

This survey presents studies about benthics marine chlorophyceae found in the Serrambi Beach, South coast of Pernambuco. The material studied was collected in three stations, which were visited monthly during the period from April, 1986 to September, 1987. The chlorophyceae were represented in this flora by 39 species, three varieties and one form, from orders Ulotrichales, Ulvales, Siphonocladales, Cladophorales, Caulerpales and Dasycladales. Acetabularia calyculus Quoy & Gaimard. In Freycinet, Bryopsis pennata Lamouroux, Bryopsis plumosa (Hudson) C. Agardh, Caulerpa ambigua Okamura, Caulerpa serrulata (Forsskal) J. Agardh emend Borgesen, Chaetomorpha brachygona Harvey, Cladophora coelothrix Kutzing, Cladophoropsis membranacea (C. Agardh) Borgesen, Codium intertextum Collins & Hervey, Ernodesmis verticillata (Kutzing) Borgesen are refered by first time from Pernambuco coast. Pringsheimiella scutata (Reinke) von Hohnel ex Marchewianka is for the continental Brazilian coast too. Halimeda opuntia (L.) Lamouroux was the host with the major number of epiphytes, while Bryopsis plumosa, when epiphyte, was the one that grew over the great number of hosts.

Halimeda cuneata (Bryopsidales, Chlorophyta), a new record for the Atlantic Ocean

Abstract Until now, Halimeda cuneata has only been known from the Indo-Pacific region. Although this taxon is represented abundantly in local herbarium collections, its presence has never been registered for Brazil. Previous studies have probably mistaken Brazilian material of H. cuneata for H. discoidea or H. tuna, when not reported as Halimeda sp. Besides giving a detailed morphological description, we describe the gametangia and include information on ultrastructure and histochemistry, aspects that have been neglected in the characterization of the genus. The discovery of H. cuneata in Brazil provides additional evidence regarding the similarities between the Indian Ocean and tropical southwestern Atlantic marine flora.

Quantitative variation of epiphytic diatoms in Galaxaura rugosa (Nemaliales: Rhodophyta)

This study aimed at describing the quantitative variations of epiphytic diatoms in Rhodophyta Galaxaura rugosa , collected in the Fernando de Noronha archipelago (north-eastern Brazil), during two annual periods (June 2006 and June 2007). The distribution of epiphytic diatoms in G. rugosa confirmed the occurrence of a quantitative variation/zoning along the thallus of the analysed host, with an increase in density (cells per gram wet weight of seaweed) of apical portions towards the basal parts of the seaweed, regardless of the collection points and the annual periods. The abundance was characterized by individuals with pennate symmetry with raphe, belonging to the Bacillariophyceae class. This fact is the result of the host being collected in an insular environment with great water movement under the direct action of trade winds and ocean currents for most of the year. The study confirmed that in marine ecosystems with strong hydrodynamics, epiphytic flora tends to comprise species with the largest adhesive strength.

Phylogenetic analyses of Cladophora vagabunda (L.) C. Hoek (Cladophorales, Chlorophyta) from Brazil based on SSU rDNA sequences

A sequencia completa do SSU rDNA foi obtida para 10 individuos de Cladophora vagabunda coletadas ao longo da costa do Brasil. Uma sequencia parcial do SSU rDNA (1634 bp) foi obtida para C. rupestris (L.) Kutz. As arvores filogeneticas indicam que Cladophora e parafiletico, mas a secao Glomeratae sensu lato compreendendo C. vagabunda do Brasil, Japao e Franca, C. albida (Nees) Kutz., C. sericea (Hudson) Kutz. e C. glomerata (L.) Kutz., e monofiletica. Dentro deste grupo, C. vagabunda e parafiletica. A identidade da sequencia para o SSU rDNA variou de 98,9% a 100% para C. vagabunda brasileira e de 98,3% a 99,7% quando comparados os individuos brasileiros aos da Franca e do Japao. A identidade da sequencia entre C. vagabunda brasileira e as duas outras especies (C. albida e C. sericea) variou entre 98,0% e 98,6%. A filogenia do SSU rDNA suporta parcialmente as caracteristicas morfologicas apresentadas pelas populacoes brasileiras de C. vagabunda. Por outro lado, C. rupestris do Brasil nao se agrupou a C. rupestris da Franca, as duas sequencias apresentaram somente 96,9% de identidade. A inclusao de sequencias de individuos do Brasil reforcam a necessidade de uma revisao taxonomica para o genero Cladophora e para o complexo C. vagabunda.

Diatomáceas epífitas em Galaxaura rugosa (J. Ellis & Solander) J.V. Lamouroux (Rhodophyta) no Arquipélago de Fernando de Noronha, PE, Nordeste do Brasil

Specimens of Galaxaura rugosa (J. Ellis & Solander) J.V. Lamouroux were collected in June 2006 and June 2007 at three localities in Fernando de Noronha Archipelago (Atalaia, Porto and Cagarras), aiming to identify the epiphytic diatom flora that inhabits the algae thallus. A total of 52 taxa were identified, distributed in the classes Coscinodiscophyceae (19%), Fragilariophyceae (21%) and Bacillariophyceae (60%) with 81% dominance of individuals with pinnate symmetry. The following species characterized the floristic diatom structure being considered very frequent: Amphora sp., Biddulphia biddulphiana (J.E. Smith) Boyer, Cocconeis scutellum Ehrenberg, Diploneis bombus Ehrenberg, Grammatophora marina (Lyngbye) Kutzing, Mastogloia binotata (Grunow) Cleve, Navicula longa Grunow, Nitzschia sp., Psammodiscus nitidus (Gregory) Round in Mann, Rhabdonema adriaticum Kutzing, Trachyneis aspera (Ehrenberg) Cleve e Tryblionella coarctata (Grunow) Mann. Specific diversity was medium to high, with lower values for the blooming of Amphora sp. (49.3%), Mastogloia binotata (42.1%) and Nitzschia sp. (62.5%).

Ceramium nitens (Ceramiaceae, Rhodophyta), an uncommon species from Brazil

Morphological studies on Ceramium nitens (C. Agardh) J. Agardh, a completely corticated species, were carried out based on specimens rediscovered in Brazil fifty years after its first record. Its occurrence in Brazil was considered doubtful since it had been collected only once since 1945. Ceramium nitens can be recognized by having axial cells entirely covered by cortical cells, except for the cells near the apex, obscuring the nodal and internodal banding thalli, characteristic of most Ceramium species. In this paper the occurrence of Ceramium nitens in Brazil is confirmed and its vegetative and tetrasporangial structures are described in detail and their implications for the taxonomy of the genera Ceramium, Centroceras and Corallophila are discussed. Brief comments on the geographic distribution of C. nitens are also included.

Community structure of epiphytic diatoms on seaweeds in Northeastern Brazil

Abstract Epiphytic diatoms associated with three species of seaweeds, the phaeophyte Bachelotia antillarum, the ulvophyte Caulerpa verticillata, and the rhodophyte Haloplegma duperreyi, were investigated in the subtidal zone of Northeastern Brazil. A total of 54 diatom species were recorded, distributed among motile (24 species), erect (20 species), and adnate growth forms (five species), in addition to accidental occurrences (five species). Although motile diatoms showed the highest number of species, erect growth forms were the most abundant, accounting for 69% of the entire epiphytic diatom cell abundance. The total abundance ranged from 29,783 to 45,842 cells g-1 wet weight (ww), with Melosira moniliformis (erect), Rhabdonema adriaticum (erect), Cocconeis scutellum (adnate), and Surirella fastuosa (motile) as the most abundant species. The results confirmed qualitative and quantitative differences between the hosts with a greater shape diversity in B. antillarum whose thalli (filamentous-like tufts) offered an increased surface area for colonization mainly by epiphytic erect growth forms.