Marcelo de Oliveira Soares

Distribution pattern of zoanthids (Cnidaria: Zoantharia) on a tropical reef

Abstract Coastal reef environments support a great diversity of benthic species, which are physically arrayed according to their adaptations to biotic factors such as competition and to abiotic factors such as salinity and desiccation. Few studies have described adaptive strategies on rocky shores in tropical regions. This contribution deals with the spatial distribution of three species of zoanthids (Palythoa caribaeorum, Protopalythoa variabilis and Zoanthus sociatus) on flat sandstone reefs in north-eastern Brazil. Zoanthid distribution and abundances were determined as the percentage of cover along six transects, where 50 × 50 cm quadrats were sampled. Biotic data (influence of macroalgal cover) and abiotic data (relief, substrate type, temperature and salinity) were also taken along the transects to attempt to explain the zoanthid distribution. These species tended to colonize the middle and low intertidal zones, which are least exposed to air. Zoanthus sociatus apparently resists desiccation better than P. caribaeorum. Protopalythoa variabilis showed the highest abundance and frequency, occurring in the entire middle intertidal zone and colonized areas with high proportions of unconsolidated sediment. Desiccation was the main factor limiting the spatial distributions of the three species, although substrate composition and probably interspecific competition with macroalgae were also important. The results suggest that the zoanthids use a variety of these adaptive strategies, which account for their success on consolidated substrates. Continuous monitoring of changes in distribution patterns can be useful for indicating human impacts on marine biodiversity, providing insights for monitoring and conservation programmes.

Competitive interactions among zoanthids (cnidaria: zoanthidae) in an intertidal zone of northeastern Brazil

Sessile organisms that live in consolidated substrates frequently compete for space. Coral species have many strategies to face this competition, including harming their opponents or hindering their growth. In the present study, the competitive interactions between three species of zoanthids were investigated in the intertidal zone of a sandstone reef environment in northeastern Brazil. The competitive abilities of the three species were evaluated by periodic observation of the natural fringes of contact and experimental evaluation of their growth rate through removal of 100 cm2 of colonies of each species. Palythoa caribaeorum and Zoanthus sociatus had similar growth rates, and both species grew faster than Protopalythoa variabilis. The recolonization strategy seems to differ among species. The contact fringes between P. caribaeorum and Z. sociatus remained unchanged over time, without any type of aggressive interaction between them, suggesting that stand-off was the strategy used by these organisms. Palythoa caribaeorum and Z. sociatus grew among the polyps of P. variabilis, often killing its colonies. The coexistence of zoanthids reveals a capacity for survival in the face of competition for limited resources such as free substrate, which led to the colonization and establishment of zoanthids in intertidal environments.

A survey of the Scyphozoa and Cubozoa (Cnidaria, Medusozoa) from the Ceará coast (NE Brazil)

Most of the scyphozoans and cubozoans recorded for the Brazilian coast are presumed to be distributed over the entire coastline, but little information on precise records is available. This paper presents the first published records for the Ceara state (northeastern region) of the cubozoan Chiropsalmus quadrumanus, and the scyphozoans Chrysaora lactea, Linuche unguiculata (polyp), Lychnorhiza lucerna, Nausithoe sp. (polyp), Phyllorhiza punctata, and Stomolophus meleagris. The medusoid species have been known by local fishermen and non-specialists for a long time in the area.

Increased anthropogenic pressure decreases species richness in tropical intertidal reefs

Multiple human stressors affect tropical intertidal sandstone reefs, but little is known about their biodiversity and the environmental impacts of these stressors. In the present study, multiple anthropogenic pressures were integrated using the relative environmental pressure index (REPI) and related to benthic community structure across an intertidal gradient in five sandstone reefs in the tropical South Atlantic coast. Greater species richness and diversity were noted in the low intertidal zones. There was a negative relationship between REPI and species richness, suggesting that increasing anthropogenic pressure has decreased benthic richness. The factors associated with the loss of richness were jetties built to control erosion, urban areas, beachfront kiosks and restaurants, fish markets, and storm sewers with illegal sewage connections. Our results highlight the need for better infrastructure planning and rigorous monitoring of coastal urban areas, since the large influence of multiple human pressures in these reefs leads to biodiversity losses.

Nutritive value of three organisms from mangrove ecosystem: Ucides cordatus (Linnaeus, 1763), Mytella sp. (Soot-Ryen, 1955) and Crassostrea rhizophorae (Guilding, 1828)

787 Nutritive value of three organisms from mangrove ecosystem: Ucides cordatus (Linnaeus, 1763), Mytella sp. (Soot-Ryen, 1955) and Crassostrea rhizophorae (Guilding, 1828) Carvalho, AFU.*, Farias, DF., Barroso, CX., Sombra, CML., Silvino, AS., Menezes, MOT., Soares, MO., Fernandes, DAO. and Gouveia, ST. Departamento de Biologia, Universidade Federal do Ceará – UFC Av. Mister Hull, s/n, Campus do Pici, CEP 60455-970, Fortaleza, Ceará, Brazil Departamento de Química Analítica, Universidade Federal do Ceará – UFC, Av. Mister Hull, s/n, Campus do Pici, CEP 60455-970, Fortaleza, CE, Brazil *e-mail: aurano@ufc.br Received November 28, 2006 – Accepted June 29, 2007 – Distributed November 30, 2007

Holocene invertebrates from the Rocas Atoll: A contribution for the ecological history of South Atlantic islands

The South Atlantic Ocean is the youngest of the world’s oceans and one of the most important biodiversity hotspots; however, there is a lack of scientific knowledge about its ecological history. Here, we present the first results of a fossil invertebrate survey from the Rocas Atoll. By using radiometric dating (C) and a survey of fossilized benthic invertebrates on this atoll, we provide new paleobiogeographic and paleoceanographic information. The results suggest eight taxa (five mollusks, two corals, and one decapod). Dates ranged from 3449 ± 790 y BP to 3033 ± 620 y BP. The data represent new invertebrate records for the middle Holocene in this atoll, and evidence of sea-level changes in this period. Considering that the Rocas Atoll is one of the newest marine atolls in the world, these results suggest recent colonization by species from the Southwestern Atlantic Coast and Fernando de Noronha Archipelago.

Aspectos biogeomorfológicos do Atol das Rocas, Atlântico Sul Equatorial

Biogeomorphological aspects of Rocas Atoll, Equatorial South Atlantic. Biogeomorphological analysis and mapping of the reef units in the only Atoll from the Equatorial South Atlantic were held for understanding the dynamics and the relief of this oceanic reef. The zoning shows the presence of the following environmental compartments: reef front, adjacent bottom, reef margin, reef flat, reef ring, reef residues, lagoon, sand flat, reef pass, pools, puddles-of-tide and the sand cays. The results show that a variety of organisms in Atoll that act in processes groups such: control of erosion on sand cays, bioprotection, bioerosion, cementation of biogenic carbonate sand, production of biodetritic sediments and bioconstruction. Such biogeomorphological processes generate some of the unique characteristics of Rocas Atoll.

Linking host morphology and symbiont performance in octocorals

Octocorals represent an important group in reef communities throughout the tropical seas and, like scleractinian corals, they can be found in symbiosis with the dinoflagellate Symbiodinium. However, while there is extensive research on this symbiosis and its benefits in scleractinians, research on octocorals has focused so far mainly on the host without addressing their symbiosis. Here, we characterized and compared the photophysiological features of nine Caribbean octocoral species with different colony morphologies (sea fan, plumes, whips and rods) and related key morphological features with their respective symbiont photobiology. Colony features (branch shape and thickness), as well as micromorphological features (polyp size, density), were found to be significantly correlated with symbiont performance. Sea fans and plumes, with thinner branches and smaller polyps, favor higher metabolic rates, compared to sea rods with thicker branches and larger polyps. Daily integrated photosynthesis to respiration ratios > 1 indicated that the autotrophic contribution to organisms’ energy demands was important in all species, but especially in sea whips. This information represents an important step towards a better understanding of octocoral physiology and its relationship to host morphology, and might also explain to some extent species distribution and susceptibility to environmental stress.

Climate change and regional human pressures as challenges for management in oceanic islands, South Atlantic

This study aimed to determine the main anthropogenic pressures and the effectiveness of management practices in marine protected areas (MPAs) (Rocas Atoll and Fernando de Noronha Archipelago, South Atlantic). The MPAs exhibited high management effectiveness over the last 25 years due to the control of local pressures (i.e., fishing and tourism). However, the increase in regional and global pressures, such as invasive species, marine debris, and climate change stressors (sea-level rise, extreme events, range shifts of species, warming, and ocean acidification), are environmental risks that need to be considered during conservation. Strategies for large scale marine spatial planning, as well as proposals for an integrated management of MPAs (including coral reef islands and seamounts) by the articulation of a network, which reduces regional human pressures and improves ocean governance were discussed. This study provided insights into the challenges faced in the management of MPAs in a rapidly changing ocean.

Marine benthic communities affected by the Doce River (southwestern Atlantic): Baseline before a mining disaster

Prior to Brazils worst environmental disaster, caused by a mining dam collapse, we had carried out a study of the marine benthic macrofauna (11-51 m depth) under the influence of the Doce River. Our results showed significant diversity, in which mollusks, polychaetes, and crustaceans had the highest frequency, density, and abundance, represented by 162 families in summer and 173 in winter. Our results suggested that richness, abundance, and diversity increase with distance from the coast. Furthermore, with increasing distance from the coast and river mouth, in addition to increasing depth, there was a differentiation in composition and abundance. Multivariate analyses showed depth, carbonate, and organic matter as important factors that explain variations in composition and diversity across the continental shelf. The results could provide an invaluable baseline for measuring the effects on shallow and mesophotic communities of one of the largest tailings dam failures worldwide.