Maria Teresa Menezes de Széchy

Padrões estruturais quantitativos de bancos de Sargassum (Phaeophyta, Fucales) do litoral dos estados do Rio de Janeiro e São Paulo, Brasil

This paper aimed to describe the biological structure of Sargassum beds along the coasts of Rio de Janeiro and Sao Paulo states. Sixteen rocky shore communities were sampled at random (50 x 50 cm quadrats) during 1991-92. These communities presented populations of distinct Sargassum species. They were chosen because they were subjected to different degrees of wave action and emersion. Seven infrageneric taxa of this genus were studied. The Sargassum dry mass varied from 37 g.m-2 to 587 g.m-2; the highest values were found in moderate and protected sites. The cluster analysis of these communities, considering the dry mass of 75 groups of macroalgae and macroinvertebrates, indicated three structural patterns characterized by the most abundant group of organisms: 1) Sargassum, in places not exposed to direct wave action, frequent emersion nor recent disturbances; 2) calcareous algae (Corallinaceae), mainly in exposed places, with Phragmatopoma lapidosa (tube worm) and/ or Perna perna (mussels); 3) other groups of non-calcareous algae, such as Dictyopteris delicatula, representative in intermediate situations. These patterns may be usefull to study the exploitation potentiality of Sargassum and other organisms, like mussels, in the Brazilian coast.

Changes in shallow phytobenthic assemblages in southeastern Brazil, following the replacement of Sargassum vulgare (Phaeophyta) by Caulerpa scalpelliformis (Chlorophyta)

Abstract The structure of shallow sublittoral phytobenthic assemblages from Ilha Grande Bay, Rio de Janeiro, southeastern Brazil, was described to evaluate the effect of the presence of Caulerpa scalpelliformis on the dominant species, Sargassum vulgare. The canopy cover of macroscopic organisms was analyzed monthly or less frequently on rocky substrata from Baleia Beach (impact location, where C. scalpelliformis appeared) and from two reference locations (without C. scalpelliformis), during the periods September 1993 to May 1995 and October 2001 to September 2003, using the point sampling method (n=5 random quadrats). At the impact location, S. vulgare was dominant from September 1993 to September 2001, when C. scalpelliformis appeared on the rocky substratum beneath S. vulgare. In a few months, the cover of S. vulgare declined dramatically and C. scalpelliformis became dominant on the rocky and sandy substrata until the end of the study. Over the same period, S. vulgare was dominant at the reference locations. Multivariate community analysis revealed significant changes in the macroalgal community structure following the appearance of C. scalpelliformis. The replacement of S. vulgare by C. scalpelliformis suggests the competitive superiority of C. scalpelliformis under sheltered conditions. This is the first record of this pantropical macroalga in the warm temperate region of the Brazilian coast.

Benthic Marine Flora of the Northeastern and Southeastern Coast of Ilha Grande, Rio de Janeiro, Brazil: Phytogeographic Considerations

Ilha Grande is situated off the coast of Rio de Janeiro State, in southeastern Brazil. A total of 128 marine algal taxa were identified, comprising 26 Chlorophyceae (20.3%), 28 Phaeophyceae (21.9%) and 74 Rhodophyceae (57.8%). The phytogeographic analysis of species from Ilha Grande, using R/P and R+C/P indices, show lower values when compared with the continental coast. Most of the differences observed were due to the higher percentage of Phaeophyceae. This paper shows that these indices should be used with caution when applied to tropical islands

Verification of Sargassum natans (Linnaeus) Gaillon (Heterokontophyta: Phaeophyceae) from the Sargasso Sea off the coast of Brazil, western Atlantic Ocean

The Sargasso Sea, named due to the floating presence of Sargassum fluitans and S. natans , is usually reported for the tropical region of the Northern Hemisphere. On 14 July 2011, at 02°45’ N and 48°28’ W, samples of pelagic seaweed masses were collected by the Patrol Ship Bracui of the Brazilian Navy. The seaweed was identified as S. natans , previously considered as of doubtful occurrence in Brazil.

The floating Sargassum (Phaeophyceae) of the South Atlantic Ocean – likely scenarios

Abstract: This study represents the efforts of a network of researchers to characterise the large, floating Sargassum (Fucales, Phaeophyceae) biomass that had reached the Brazilian coast in 2014 and 2015. Material collected during these events was identified as Sargassum natans and S. fluitans using morphological characteristics; ITS2 sequences showed low divergence (0%–3%) with sequences of nine other Sargassum species. Several epiphytic macroalgae, invertebrates and fishes were associated with the floating Sargassum. Satellite images did not support the hypothesis of slicks moving south from the Sargasso Sea in the northern Atlantic Ocean. This strengthens the hypothesis that there is a matrix of pelagic Sargassum in the central Atlantic Ocean and that biomass accumulation should be considered a result of the combination of physicochemical seawater conditions and biological interactions. The biomass accumulation of the stranded Sargassum was estimated during four events, peaking in 98 kg m−2 wet weight on a beach on the Amazonian coast. The landing of huge Sargassum biomass represents a potential source of environmental stress, as it can lead to an increase in oxygen demand and eventually synthesise and release chemical compounds with allelopathic properties. On the other hand, these floating islands are a fundamental element of the biogeography and macroecology of tropical environments in the Atlantic Ocean, providing connectivity south/north and east/west among marine biodiversity from Atlantic reef environments. Studies concerning Sargassum effects on local communities are necessary for the proper management of this phenomenon.

Flora ficológica da região sublitorânea rasa de costões rochosos do Núcleo Picinguaba, Parque Estadual da Serra do Mar, Ubatuba, São Paulo

Em unidades de conservacao da zona costeira, o conhecimento das macroalgas marinhas e essencial para monitoramento e manejo. Para o Nucleo Picinguaba do Parque Estadual da Serra do Mar (PESM), Ubatuba, norte do Estado de Sao Paulo, estudos preteritos realizados na Enseada da Fazenda listam especies de macroalgas, coletadas em costoes rochosos e manguezais. O presente estudo visou complementar o levantamento taxonomico da flora ficologica marinha do Nucleo Picinguaba, avaliando tambem a adequacao da metodologia para amostragens de suas comunidades de costoes rochosos. Foram selecionados 13 pontos de coleta, entre a Ponta da Almada e a Ponta do Cambury, area de maior interferencia antropogenica na zona costeira do PESM. No verao de 2007, foram efetuadas coletas de macroalgas, desde a franja da regiao sublitorânea ate o limite do substrato rochoso com a areia. Para uniformizar o esforco amostral, estas buscas foram efetuadas, em cada ponto de coleta, pelo mesmo especialista, durante uma hora de mergulho em apneia, em uma extensao horizontal do costao rochoso de cerca de 20 m. Foram identificados 128 taxons de categoria infragenerica (80 Rhodophyta, 22 Ochrophyta e 26 Chlorophyta). Callithamniella flexilis Baardseth, Cryptonemia seminervis (C. Agardh) J. Agardh, Cladophora pseudorupestris C. Hoek e Cladophora cf. pygmaea Reinke sao ocorrencias novas para o litoral do Estado de Sao Paulo, tendo sido descritas e ilustradas. Foram acrescentadas 64 especies de macroalgas para os costoes rochosos do PESM. O esforco amostral foi considerado adequado, resultando na identificacao de numero de especies de macroalgas similar ao de outros estudos realizados no litoral norte do estado de Sao Paulo e no extremo sul do estado do Rio de Janeiro. Para o monitoramento da zona costeira desta unidade de conservacao, recomenda-se o levantamento taxonomico das macroalgas dos costoes rochosos de modo continuado, durante o periodo de verao de anos sucessivos, seguindo a mesma metodologia aqui descrita.

Abundance of the reef-building Petaloconchus varians (Gastropoda: Vermetidae) on intertidal rocky shores at Ilha Grande Bay, southeastern Brazil

The reef-building vermetid Petaloconchus varians occurs in the western Atlantic Ocean, from the Caribbean Sea to the southern coast of Brazil. The present study evaluated the abundance of P. varians on intertidal rocky shores in Ilha Grande Bay (Rio de Janeiro State), and characterized their reefs, describing the species density, besides the weight and the belt width of the reefs. Petaloconchus varians reefs were recorded at 25 sites, with rocky shores exposed to different wave action (very sheltered, sheltered, semi-exposed and exposed) and slopes (10° to 46°). Clusters of individuals constructed large reefs along the middle intertidal zone, creating a wide belt (38 cm to 2 m). The density of P. varians and the weight of the reefs ranged from 620 to 2,559 ind.100 cm-2 and from 100 to 1,500 g.100 cm-2, respectively. Considering that the species was last reported from the area in the mid-20th century, the present study suggests that P. varians reefs are becoming dominant in the intertidal zone of rocky shores in Ilha Grande Bay. This is a contribution to knowledge of this ecosystem in Ilha Grande Bay, in view of local or global ecological changes.

THE STRUCTURE OF SUBTIDAL MACROALGAL ASSEMBLAGES AT THE TAMOIOS ECOLOGICAL STATION, A THREATENED CONSERVATION UNIT IN RIO DE JANEIRO, BRAZIL

B S T R A C T The structure of subtidal rocky bottom communities at Tamoios Ecological Station (TES), situated in Ilha Grande Bay, Rio de Janeiro State, as well as in other Brazilian marine protected areas, is insufficiently characterized. The present study describes the macroalgal assemblages of shallow subtidal rocky bottoms on two islands of the TES-Imboassica (IM) and Buzios Pequena (BP)-adopting species and genera as observational units. Two sites were surveyed on each island in summer 2011. Random 30x30 cm quadrats (n=3) were scraped to collect all macroalgae except crustose species. The subtidal assemblages, in which 58 macroalgal species occurred, were characterized by the high frequency and percent cover of

The occurrence of Boodleopsis vaucherioidea Calderón-Sáenz et Schnetter (Udoteaceae, Chlorophyta) in Brazil

Abstract Up to the present time, Boodleopsis (Udoteaceae, Chlorophyta) has been represented on the Brazilian coast by Boodleopsis pusilla only. This study describes B. vaucherioidea from the southern coast of Rio de Janeiro State, Brazil. Non-fertile plants were collected in April, June and November 2000, and January 2003, and then compared with the holotype from the Colombian Caribbean Sea. Considering field and cultured plants, the Brazilian specimens were identified as B. vaucherioidea, and distinguished from B. pusilla by the upright filaments without constrictions above the forks, and their divaricate branchlets. This is the first record of B. vaucherioidea for the south Atlantic Ocean.