Citizen science as a tool for understanding the silent dispersion of toadfish Opsanus beta (Goode and Bean, 1880).

Citizen science is an excellent tool in studies of the spatial distribution of non-native species. In Brazil, Opsanus beta has recently been introduced. Studies indicate the occurrence of this species in five estuaries off the Brazilian coast (Guanabara Bay, Sepetiba Bay, Santos Bay, Paranaguá Estuarine Complex and Guaratuba Bay). The present study aims to understand the dispersion of this species on the Brazilian coast through citizen science. Between January and May 2021, information about O. beta was weekly posted in 32 recreational fishing Facebook groups. Sixty-five fishers reported catches of O. beta in estuaries (Guanabara Bay, Sepetiba Bay, Santos Bay and Paranaguá Estuarine Complex). In addition, there were reports from other shallow areas outside adjacent estuaries (Bertioga and Peruíbe, in Sao Paulo State) and the first occurrence record for Laguna (Santa Catarina State), a southern estuarine zone (28° 29' 45″ S to 48° 45' 36″ W). In four estuaries along the Brazilian coast where O. beta was recorded, there are internal ports that trade with countries from the Gulf of Mexico and Caribbean Sea (species original range), indicating ballast water as a possible introduction route. In Laguna, the introduction may have occurred by maritime cabotage services. The reproductive capacity, the aquarists' interest, the absence of introduction policies aimed at this species and the cabotage fleet transportation may be factors that help further extend the dispersal of O. beta on the Brazilian coast.

Decadal (2006-2018) dynamics of Southwestern Atlantic's largest turbid zone reefs.

Tropical reefs are declining rapidly due to climate changes and local stressors such as water quality deterioration and overfishing. The so-called marginal reefs sustain significant coral cover and growth but are dominated by fewer species adapted to suboptimal conditions to most coral species. However, the dynamics of marginal systems may diverge from that of the archetypical oligotrophic tropical reefs, and it is unclear whether they are more or less susceptible to anthropogenic stress. Here, we present the largest (100 fixed quadrats at five reefs) and longest time series (13 years) of benthic cover data for Southwestern Atlantic turbid zone reefs, covering sites under contrasting anthropogenic and oceanographic forcing. Specifically, we addressed how benthic cover changed among habitats and sites, and possible dominance-shift trends. We found less temporal variation in offshore pinnacles' tops than on nearshore ones and, conversely, higher temporal fluctuation on offshore pinnacles' walls than on nearshore ones. In general, the Abrolhos reefs sustained a stable coral cover and we did not record regional-level dominance shifts favoring other organisms. However, coral decline was evidenced in one reef near a dredging disposal site. Relative abundances of longer-lived reef builders showed a high level of synchrony, which indicates that their dynamics fluctuate under similar drivers. Therefore, changes on those drivers could threaten the stability of these reefs. With the intensification of thermal anomalies and land-based stressors, it is unclear whether the Abrolhos reefs will keep providing key ecosystem services. It is paramount to restrain local stressors that contributed to coral reef deterioration in the last decades, once reversal and restoration tend to become increasingly difficult as coral reefs degrade further and climate changes escalate.

Tropical rhodolith beds are a major and belittled reef fish habitat.

Understanding habitat-level variation in community structure provides an informed basis for natural resources' management. Reef fishes are a major component of tropical marine biodiversity, but their abundance and distribution are poorly assessed beyond conventional SCUBA diving depths. Based on a baited-video survey of fish assemblages in Southwestern Atlantic's most biodiverse region we show that species composition responded mainly to the two major hard-bottom megahabitats (reefs and rhodolith beds) and to the amount of light reaching the bottom. Both megahabitats encompassed typical reef fish assemblages but, unexpectedly, richness in rhodolith beds and reefs was equivalent. The dissimilar fish biomass and trophic structure in reefs and rhodolith beds indicates that these systems function based on contrasting energy pathways, such as the much lower herbivory recorded in the latter. Rhodolith beds, the dominant benthic megahabitat in the tropical Southwestern Atlantic shelf, play an underrated role as fish habitats, and it is critical that they are considered in conservation planning.

First year after the Brumadinho tailings' dam collapse: Spatial and seasonal variation of trace elements in sediments, fishes and macrophytes from the Paraopeba River, Brazil.

On January 2019, the B1 iron ore tailings' dam collapsed in Brumadinho, Brazil, being one of the worst mining-related disasters, with 270 human deaths (11 of them still missing) and 12.106 m3 of tailings released to the environment. The tailings devastated the Córrego do Feijão brook and reached the adjacent Paraopeba River, the region's main watercourse and a major tributary of the São Francisco basin. Although physicochemical parameters of the river were strongly impacted, and acute toxicological effects have been reported from exposure experiments, contamination of aquatic biota had not yet been assessed. Therefore, the aim of this study was to evaluate contamination by trace elements (As, Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn) in sediment, fish and macrophytes along the Paraopeba River, upstream and downstream from the dam failure site, during the dry and wet season. With the exception of Cd and Hg, all elements in sediment samples had lower median concentrations downstream. An inverse pattern was observed for the aquatic biota, with significant higher concentrations of Fe, Mn, Ni and Zn in fishes, and increased concentrations of most elements in macrophytes, indicating an increase in element bioavailability. A significant seasonal variation was observed with increased concentrations of As (dry season) and Pb (wet season) in fish samples, with the same trend occurring in macrophytes. Concentrations of potentially toxic elements in fish samples in wet weight (Cr: 1.80 ± 1.31 mg kg-1, Hg: 0.21 ± 0.11 mg kg-1 and Pb: 0.79 ± 0.80 mg kg-1) were lower than those reported before the disaster. Furthermore, As and Pb concentrations exceeded the safety threshold for fish consumption in 3% and 41% of samples, respectively, representing a matter of concern for public health.

Age, growth, reproduction and management of Southwestern Atlantic's largest and endangered herbivorous reef fish, Scarus trispinosus Valenciennes, 1840.

The Brazilian-endemic greenbeack parrotfish, Scarus trispinosus Valenciennes, 1840, is the largest herbivorous reef fish in the South Atlantic. Following the sharp decline of large carnivorous reef fishes, parrotfishes (Labridae: Scarinae) were progressively targeted by commercial fisheries in Brazil, resulting in a global population decline of 50% for S. trispinosus. Most of its remnant population is concentrated in the Abrolhos Bank, where the present study was conducted. We present novel information on age, growth and the reproductive cycle of S. trispinosus, based on 814 individuals obtained from commercial fisheries' landings and scientific collections, between 2010 and 2013. Sex ratio was biased toward females (1:8), and spawning occurred year-round with discrete peaks in February-March and June-December. Increment analysis indicated annual deposition of growth rings in otoliths, which presented 1-22 rings. The asymptotic length at which growth is zero (L ∞) was estimated from a Bayesian logistic regression at 85.28 cm, growth rate (K) at 0.14 year-1, and the theoretical age at zero size (t 0) at 0.16. Subregional demographic structuring was detected, with predominance of slower-growing individuals in shallower inshore reefs and predominance of faster-growing and older individuals in deeper offshore sites. We demonstrate that S. trispinosus is highly vulnerable to over-exploitation due to its large size, long live and slow-growth, and review the management measures proposed since its Red List assessment in 2012.

Feeding ecology of two sympatric species of large-sized groupers (Perciformes: Epinephelidae) on Southwestern Atlantic coralline reefs

Red and black groupers are large-bodied opportunistic ambush predators commonly found in Southwestern Atlantic tropical reefs. We investigated the diet of both species in order to detail ontogenetic, spatial and temporal trends, and to assess the extent of overlap in resource use between these two sympatric predators on the Abrolhos Bank, Brazil. Decapods and fishes were the main food items of Epinephelus morio while fishes were the main prey of Mycteroperca bonaci. Both diets were significantly influenced by body size and habitat, but only smaller individuals of E. morio feed almost exclusively on crustaceans. While the two groupers rely on many of the same prey types, coexistence may be facilitated by E. morio feeding more heavily on crustaceans, particularly the blackpoint sculling crab Cronius ruber, while black grouper take comparatively few crustaceans but lots of fish prey. Predators like red and black groupers could trigger indirect effects in the community and influence a large range of ecological processes, such as linkages between top and intermediate predators, and intermediate predators and their resources.(AU)

A garoupa e o badejo-verdadeiro são predadores oportunistas de grande porte, com estratégia de emboscada, comumente encontrados em recifes tropicais do Atlântico Sul. A dieta das duas espécies foi investigada, avaliando influências ontogenéticas, espaciais e temporais, assim como a sobreposição no uso de recursos entre estes dois predadores co-orrentes no Banco dos Abrolhos, Brasil. Decápodes e peixes foram os principais itens alimentares de Epinephelus morio, enquanto que os peixes foram as principais presas de Mycteroperca bonaci. Ambas as dietas foram significativamente influenciadas pelo tamanho corporal e habitat, mas apenas indivíduos menores de E. morio alimentaram-se quase que exclusivamente de crustáceos. Como as duas espécies utilizam muitas presas semelhantes, a coexistencia parece ser facilitada pelo fato de E. morio se alimentar principalmente de crustáceos, particularmente do caranguejo Cronius ruber, enquanto que o badejo-verdadeiro consome relativamente poucos crustáceos e grande quantidade de peixes. Predadores como as espécies estudadas podem causar efeitos indiretos na comunidade e influenciar uma grande variedade de processos ecológicos, como conexões entre predadores de topo e intermediários e predadores intermediários e seus recursos.(AU)

Blood parameter analysis and morphological alterations as biomarkers on the health of Hoplias malabaricus and Geophagus brasiliensis

Este trabalho teve como objetivo avaliar a influência do ambiente sobre a higidez dos peixes. Animais, das espécies Hoplias malabaricus e Geophagus brasiliensis foram coletados em três ambientes distintos, sendo ambiente I região urbana e ambientes II e III em região rural. Foram realizadas análises do número total de eritrócitos por microlitro de sangue, microhematócrito, taxa de hemoglobina, porcentagem de leucócito e contagem diferencial de leucócitos em extensão sanguínea. Calcularam-se os índices hematimétricos absolutos: volume corpuscular médio e concentração de hemoglobina corpuscular média. Para análises das alterações morfológicas, brânquias, fígado, gônadas e rim seguiram processamento histológico de rotina. Foram observados índices hematológicos ligeiramente menores em indivíduos coletados no ambiente III em relação aos animais coletados no ambiente I. As análises histológicas de brânquias, fígado e gônadas das espécies G. brasiliensis e H. malabaricus demonstraram alterações morfológicas em porcentagens baixas. Foram identificas alterações internas nos rins, sendo representadas por degeneração e cristalização no interior dos túbulos renais. Em 92% dos indivíduos de G. brasiliensis, coletados no ambiente I, foi observado cristalizações no interior de túbulos. Sugere-se que tais alterações estejam relacionadas com a baixa circulação de água no local.