Robson Guimarães dos Santos

Debris ingestion by juvenile marine turtles: An underestimated problem

Marine turtles are an iconic group of endangered animals threatened by debris ingestion. However, key aspects related to debris ingestion are still poorly known, including its effects on mortality and the original use of the ingested debris. Therefore, we analysed the impact of debris ingestion in 265 green turtles (Chelonia mydas) over a large geographical area and different habitats along the Brazilian coast. We determined the death rate due to debris ingestion and quantified the amount of debris that is sufficient to cause the death of juvenile green turtles. Additionally, we investigated the original use of the ingested debris. We found that a surprisingly small amount of debris was sufficient to block the digestive tract and cause death. We suggested that debris ingestion has a high death potential that may be masked by other causes of death. An expressive part of the ingested debris come from disposable and short-lived products.

Reef fish structure and distribution in a south-western Atlantic Ocean tropical island

The community structure of the reef fish fauna of Trindade Island, a volcanic oceanic island located 1160 km off the coast of Brazil, is described based on intensive visual censuses. Seventy-six species were encountered in 252 censuses, with mean ± S.E. of 99 ± 3 individuals and 15.7 ± 0.3 species 40 m(-2) transect. The average fish biomass, calculated from length-class estimation, was 22.1 kg 40 m(-2) transect. The species contributing most to biomass were, in decreasing order, Melichthys niger, Cephalopholis fulva, Kyphosus spp., Holocentrus adscensionis, Sparisoma amplum, Sparisoma axillare, Acanthurus bahianus and Epinephelus adscensionis. Carnivorous fishes were the largest trophic group in terms of biomass, followed by omnivores and roving herbivores. The two predominant types of reef habitat, fringing reefs built by coralline algae and rocky reefs made of volcanic boulders, showed significant differences in the biomass and the abundance of the trophic guilds. Within each habitat type, significant differences in species richness, density and biomass were detected among crest, slope and interface zones. Although similar in overall species composition to coastal reefs in Brazil, the fish fauna of Trindade Island shares certain characteristics, such as a high abundance of planktivores, with other Brazilian oceanic islands. Despite comparatively high fish biomass, including the macro-carnivorous species habitually targeted by fisheries, signs of overfishing were evident. These findings highlight the urgency for a conservation initiative for this isolated, unique and vulnerable reef system.

Relationship between fibropapillomatosis and environmental quality: a case study with Chelonia mydas off Brazil

We documented the presence of fibropapillomatosis (FP), a debilitating tumor-forming disease, in marine turtles in Espirito Santo Bay (Brazil) from March 2007 to April 2008, and assessed the value of a specific environmental index for predicting the prevalence of FP. Turtles were captured monthly with entanglement nets and scored for presence and severity of FP. For the assessment of habitat quality, we used the ecological evaluation index (EEI) based on benthic macrophytes. The FP-free control area was classified as good quality (EEI = 8) and the study area, with high FP prevalence, was classified as bad quality (EEI= 2). Prevalence of FP in the study area was 58.3% with an average of 40 tumors per individual, and prevalence varied positively with curved carapace length (CCL). No FP was seen in the control area. The number of turtles heavily afflicted (tumor score category 3) was 10 times larger than those lightly affected (tumor score category 1). Most tumors were found on or near the front and rear flippers; no oral tumors or internal tumors were found. At recapture, 41% of formerly tumor-free turtles revealed FP, often increasing in severity with time, and very few turtles showed signs of disease regression. From the results of this study we concluded that FP is particularly severe in Espírito Santo Bay. Future studies should focus on evaluating how widespread FP is in Brazil, whether prevalence is increasing or decreasing, and elucidating the pathology and pathogenesis of FP in sea turtles in Brazil.

Coastal habitat degradation and green sea turtle diets in Southeastern Brazil.

To show the influence of coastal habitat degradation on the availability of food for green turtles (Chelonia mydas), we assessed the dietary preferences and macroalgae community at a feeding area in a highly urbanized region. The area showed low species richness and was classified as degraded. We examined stomach contents of 15 dead stranded turtles (CCL=44.0cm (SD 6.7cm)). The diet was composed primarily of green algae Ulva spp. (83.6%). In contrast, the macroalgae community was dominated by the green alga Caulerpa mexicana. We found a selection for red algae, seagrass and Ulva spp., and avoidance for C. mexicana and brown alga Dictyopteris delicatula. The low diversity of available food items, possibly a result of environmental degradation, likely contributed to the low dietary diversity. The nutritional implications of this restricted diet are unclear.

Direct Evidence for Gradual Ontogenetic Dietary Shift in the Green Turtle, Chelonia mydas

Abstract Here we provide information on the diet of juvenile green turtles from neritic developmental habitats in the South Atlantic that indicates the existence of a gradual dietary shift from a primarily carnivorous to a primarily herbivorous diet. Linear regression showed a relation between the size of turtles (n  =  22) and the proportion of vegetal matter in the diet, with smaller animals being predominantly carnivorous. We propose 3 hypotheses that could explain these observations.

A new record of whale shark Rhincodon typus in Brazilian waters: a report of association with Caranx crysos

In May 2011, a Rhincodon typus was sighted on the continental shelf of the central Brazilian coast, in the vicinity of a gas platform. During the video record, an interspecific following association was observed between a Caranx crysos school and the R. typus.

Challenges in Evaluating the Severity of Fibropapillomatosis: A Proposal for Objective Index and Score System for Green Sea Turtles (Chelonia mydas) in Brazil.

Fibropapillomatosis (FP) is a neoplastic disease that affects marine turtles worldwide, especially green sea turtles (Chelonia mydas). FP tumors can develop on the body surface of marine turtles and also internally in the oral cavity and viscera. Depending on their quantity, size and anatomical distribution, these tumors can interfere with hydrodynamics and the ability to feed, hence scoring systems have been proposed in an attempt to quantify the clinical manifestation of FP. In order to establish a new scoring system adapted to geographic regions, we examined 214 juvenile green sea turtles with FP caught or rescued at Brazilian feeding areas, counted their 7466 tumors and classified them in relation to their size and anatomical distribution. The patterns in quantity, size and distribution of tumors revealed interesting aspects in the clinical manifestation of FP in specimens studied in Brazil, and that FP scoring systems developed for other areas might not perform adequately when applied to sea turtles on the Southwest Atlantic Ocean. We therefore propose a novel method to evaluate the clinical manifestation of FP: fibropapillomatosis index (FPI) that provides the Southwest Atlantic fibropapillomatosis score (FPSSWA). In combination, these indexing and scoring systems allow for a more objective, rapid and detailed evaluation of the severity of FP in green sea turtles. While primarily designed for the clinical manifestation of FP currently witnessed in our dataset, this index and the score system can be adapted for other areas and compare the characteristics of the disease across regions. In conclusion, scoring systems to classify the severity of FP can assist our understanding on the environmental factors that modulate its development and its impacts on the individual and population health of green sea turtles.

Spatial distribution and diet of Cephalopholis fulva (Ephinephelidae) at Trindade Island, Brazil

,respectively. This species is regularly distributed along the costal environments of the Trindade Island, with no significantdifferences in densities and biomass detected among the different collection habitats (reef crest, reef slope, and reef plateau).However, significantly higher densities were observed micro-habitats with greater structural complexity, which may offer moreshelter and food to

Marine debris in Trindade Island, a remote island of the South Atlantic

Marine debris is widespread in oceans worldwide, including the most remote locations. Here, for the first time, we report macro-debris accumulation on beaches of Trindade Island, a remote island 1160 km from mainland Brazil. High debris density was recorded on windward, east-coast beaches, which are exposed to wind-driven currents. Small-sized plastic fragments were the most abundant debris. Polyethylene (67%), polypropylene (30%) and polyamide (3%) were the most prevalent polymeric materials identified by ATR-FTIR. Identified debris show that interaction with Trindade fauna, mainly with seabirds and endangered terrestrial crabs, exists and already has some impact. This study provides baseline information on Trindade macro-debris demonstrating that the island, located on the edge of the South Atlantic Gyre, acts as a sink for gyre debris, exposing the island fauna to the threats related to plastic contamination.