Andrea O. R. Junqueira

Effects of organic pollution on the initial development of fouling communities in a tropical bay, Brazil.

Transplantation of artificial panels between a polluted and an unpolluted site was used to evaluate eutrophication effects on the development of fouling communities in Ilha Grande Bay, SE Brazil. Organic pollution changed the relative dominance of species in the fouling communities of transplanted panels, although, their richness, evenness, and specific composition did not change. The chlorophyte Ulva sp. occurred only in the polluted site and in panels transplanted to it, whereas the bryozoan Aetea lingulata was found only in the unpolluted site and in panels transplanted to this site. These species are therefore good pollution indicators. The best pollution indicators, however, were amphipods and Spionidae polychaetes which formed mucous tubes. These groups had significantly higher values of percent cover (p<0.0001) in the polluted site and in panels transferred to it. The dominance shift is the first evidence that more meaningful changes can occur in the structure of fouling communities on a long-term scale.

Non indigenous ascidians in port and natural environments in a tropical Brazilian bay

Despite limited natural dispersal, some species of ascidians can be transported vast distances via oceanic petroleum platforms, ship hulls and ballast water and therefore may be good indicators of bioinvasion. Usually non indigenous species (NIS) are abundant in harbors. This is caused in part because of the higher propagule delivery rate in these areas. An alternative explanation of why invasion is enhanced in harbor and marinas is that environmental degradation commonly found in these habitats favors the establishment of NIS. Most surveys for introduced species were not comprehensive and targeted mainly ports and marinas. Angra dos Reis is an excellent system that provides an opportunity to compare the potential distribution of introduced and native species of Ascidiacea between port and natural environments. Here, we compared the colonization of experimental subtidal plates placed in harbors and marinas with the colonization of plates placed in nearby natural areas. With 27 taxa (15 identified to species), species richness was greater in port environments (25 versus 8). Six taxa were common to both environments while 19 taxa were exclusively found in ports. Among the identified species in ports, three were introduced, five were cryptogenic and only one was native. Only three species were found exclusively in the natural sites and all were cryptogenic. The presence of introduced species only in the port areas of Angra dos Reis reinforces the need for continued, periodic monitoring in the region for early detection of new, potentially invasive, species as well as for better understanding of abnormal population growth of the already known species. Management to reduce the transfer of exotics to natural habitats must be implemented.

Marine Bioinvasions in the Brazilian Coast: Brief Report on History of Events, Vectors, Ecology, Impacts and Management of Non-indigenous Species

The Brazilian coast extends for about 8000 km from Cape Orange (4°N) to Chui (34°S) (Fig. 27.1). This long coastline comprises a variety of ecosystems under the influence of oligotrophic waters transported by two western boundary currents, the Brazil and North Brazil currents (Stramma and England 1999), together with continental influences related to a wide spectrum of river inputs, the largest of which being the massive Amazon River plume in the north and the combination of the La Plata and Patos Lagoon outflows in the south (Castro Filho and Miranda 1998). Seasonal or intermittent intrusions of cold and nutrient-rich oceanic waters carried underneath the Brazil and North Brazil currents (the so-called South Atlantic Central Water) is another important physical forcing on regional shelf ecosystems of Brazil, particularly on the Southern Brazilian Bight and more southern areas (Lopes et al. 2006). Regionally important coastal ecosystems are (1) sandy beaches, occurring from north to south, with the largest ones in southernmost areas of the state of Rio Grande do Sul; (2) mangrove forests, which occur from the northern tip of the country to the state of Santa Catarina in the south, (3) coral reefs, ranging from Maranhão to Bahia including the largest coral reef system of the South Atlantic, the Abrolhos Reefs (Leão et al. 2003); (4) rocky shores, spread along the entire coast from the northeast to the south, but more extensive in the southeast; (5) coastal lagoons, such as the Cananéia-Iguape estuarine complex in the state of São Paulo and the Patos Lagoon in the state of Rio Grande do Sul; (6) saltmarshes, of regional importance only south of the state of São Paulo; and (7) sandy to muddy bottoms of the infralitoral realm down to the shelf break (Seeliger and Kjerfve 2000). Given such a large array of marine ecosystems and the extent of the Brazilian coastline, the country is undoubtedly a major receptor and donor of tropical and subtropical organisms in the world’s oceans. Research on marine bioinvasions is a relatively new topic in Brazil. The first comprehensive lists of introduced and invasive species are starting to be compiled and the understanding of patterns of invasion strategies is far from being accom-

Population recovery of the sea urchin Lytechinus variegatus in a seagrass flat (Araruama Lagoon, Brazil): the role of recruitment in a disturbed environment

Summary The size, structure, and density of a population of Lytechinus variegatus were recorded from a shallow seagrass bed (Halodule wrightii) at 40-day intervals from April 1994 to April 1995. A local mass mortality was observed in May 1994. The density declined from 0.57±0.10 to 0.06±0.05 ind.m−2, mean size declined from 37.6±0.49 to 16.2±2.14 mm and maximum size from 75 to 40 mm. Ten months after mortality, the maximum and mean sizes had returned to initialvalues, but density had not (0.10±0.03 ind.m−2). A second, smaller mass mortality occurred in April 1995. High values of gonad index were recorded before mortality (9.40±5.97) and after population recovery (11.96±5.74). Recruitment was continuous throughout the year, but reached a peak from August to October. This can he related to the patterns of upwelling in the region. Mass mortality is probably an annual event in this population that can be correlated with the occurrence of low tides during daytime in the fell. The population can recover during ...

Bioinvasion in a Brazilian Bay: Filling Gaps in the Knowledge of Southwestern Atlantic Biota

Background Biological invasions are a major cause of global species change. Nevertheless, knowledge about the distribution and ecology of introduced species is regionally biased, and many gaps in knowledge exist for most developing countries. Methodology/Principal Findings To study the zoobenthos on the hard substratum of the Ilha Grande Bay, a survey was conducted on both natural and artificial substrata at three depths and seven sites. The species recorded were classified as native, cryptogenic or introduced. Multivariate analyses were conducted to assess the prevalence of introduced species in these communities and to compare the distribution of species on natural and artificial substrata of this bay to identify possible discrepancies in habitat use. Of the 61 species, 25 were cryptogenic, 10 were introduced and 26 were native. Similar numbers of introduced species were found on both natural and artificial substrata, though the community composition was significantly different between them. We also compared the species composition of the Ilha Grande Bay survey to other inventories taken around the world. The highest similarities were found between the Ilha Grande Bay inventory and the Atlantic coastal region (Tampa Bay, USA and the Gulf of Mexico), American Samoa and Pearl Harbor (USA) inventories. Conclusions/Significance This study presents the first published comprehensive list of hard substratum sessile marine invertebrate species in a Brazilian bay. The high percentage of cryptogenic species reveals gaps in both zoological records and information on introduced species for the Brazilian coast. The introduced species successfully colonized different sites in the Ilha Grande Bay, including both natural and artificial substrata. In addition, we find that artificial structures may not be good surrogates for natural rocky shores and may represent an ecological threat. Comparisons with other inventories suggest a history of broad-scale invasion, though more evidence is needed to support this conclusion.

Succession in rocky intertidal benthic communities in areas with different pollution levels at Guanabara Bay (RJ-Brazil)

The aim of this study was to describe and compare the succession of intertidal benthic communities in two areas at Guanabara Bay, RJ, Brazil: Urca, an area submitted to moderated organic pollution and Catalao, an extremely polluted area. Three transects in each area were scraped one month before the beginning of this study in order to evaluate the recruitment (recruitment-treatments). Three other transects were monitored without manipulation (monitoring treatments). Species composition and relative abundance were evaluated monthly between September and December, 2000. A total of 26 species was found at Urca and 13 at Catalao. The percent cover of the most abundant organisms was not similar between treatments at Urca after four months, while in Catalao, the similarity was 72% in the second month. The faster community development and recovery at the most polluted area was probably related to the existence of simple and resilient communities in more impacted areas.

The invasion of the azooxanthellate coral Tubastraea (Scleractinia: Dendrophylliidae) throughout the world: history, pathways and vectors

In this review, we describe the history, pathways and vectors of the biological invasion of the azooxanthellate coral Tubastraea (Scleractinia: Dendrophylliidae) throughout the world. In order to do so we consulted previous reports in the literature and also compiled new unpublished information on the distribution of the three species of Tubastraea which have been reported as non indigenous species, both within their native and non-native ranges and also on vectors, and where cryptogenic. We combine these data with historical aspects of marine vectors in order to get insights into how Tubastraea species have successfully spread around the world, established and invaded and where future studies would be best focused. T. coccinea and T. tagusensis are recognized as being highly invasive and are causing significant environmental, economic, and social impacts requiring management actions. The third species, T. micranthus so far only reported outside its native range on oil platforms, may have similar potential for negative impact. The vectors of introduction of Tubastraea may have changed throughout history and the biological invasion of these invasive corals may reflect changing practices, demands and legislation in shipping activities over the years. Today it is clear that these corals are fouling organisms strongly associated with oil and gas platforms worldwide which are thus primary vectors for new introductions.

A comparative study of the methods used to evaluate the activity of Teredinidae molluscs

Abstract Different methodologies are usually employed to evaluate Teredinidae wood-boring activity. Many authors using panels made of solid wood, estimated density by counting Teredinidae punctures on the wood surface or using x-ray techniques. However this technique does not allow the identification of species. A second approach, employing a collecting device made of sheets of wood, can be more effective for quantitative and qualitative analyses. The present paper compares density, species composition and diversity when using both solid and sheet panels. In addition different methods of estimating density were analysed. The results show that the evaluation of Teredinidae activity can change according to the methodology employed.

Method for monitoring intertidal communities in a steep rocky shore: a combination of digital image technology and field operational strategy

This paper introduces a method for temporal studies of steep rocky intertidal communities. It combines the use of digital image technology with field methodology, so that a wide area of the community can be sampled in a short time. Two current nondestructive percent cover estimation methods (visual estimation and point intersection) were compared in terms of cost, operational advantages and data quality, with a proposed method for a sucessional study . The proposed method used sequential photos to sample multiple fixed vertical transects over time. Reproduction of the mid-intertidal transect over time was possible by overlaying temporal transects in an image editing program. This method was similar to the point intersection quadrat method used to estimate percent cover. Benefits included reduced time on field work, economic advantages and other advantages of using digital photography, such as recording. Temporal photography of transects provided measurements of recruitment, mortality and population growth, and made it possible to manufacture an animation of sucessional stages. We suggest that this is the best method for providing information and understanding on the process of succession and for monitoring benthic invertebrate intertidal communities on steep rocky shores.

How Much Is Too Little to Detect Impacts? A Case Study of a Nuclear Power Plant

Several approaches have been proposed to assess impacts on natural assemblages. Ideally, the potentially impacted site and multiple reference sites are sampled through time, before and after the impact. Often, however, the lack of information regarding the potential overall impact, the lack of knowledge about the environment in many regions worldwide, budgets constraints and the increasing dimensions of human activities compromise the reliability of the impact assessment. We evaluated the impact, if any, and its extent of a nuclear power plant effluent on sessile epibiota assemblages using a suitable and feasible sampling design with no ‘before’ data and budget and logistic constraints. Assemblages were sampled at multiple times and at increasing distances from the point of the discharge of the effluent. There was a clear and localized effect of the power plant effluent (up to 100 m from the point of the discharge). However, depending on the time of the year, the impact reaches up to 600 m. We found a significantly lower richness of taxa in the Effluent site when compared to other sites. Furthermore, at all times, the variability of assemblages near the discharge was also smaller than in other sites. Although the sampling design used here (in particular the number of replicates) did not allow an unambiguously evaluation of the full extent of the impact in relation to its intensity and temporal variability, the multiple temporal and spatial scales used allowed the detection of some differences in the intensity of the impact, depending on the time of sampling. Our findings greatly contribute to increase the knowledge on the effects of multiple stressors caused by the effluent of a power plant and also have important implications for management strategies and conservation ecology, in general.