Carbonic anhydrase in elasmobranchs and current climate change scenario implications.

The enzyme carbonic anhydrase (CA) has well-known functions in acid-base balance, respiratory gas exchange, and osmoregulation in teleost fishes. However, studies concerning the role of CA in elasmobranchs are still scarce. Therefore, the aim of this study is to present the current status of CA studies in sharks and rays, as well as to identify gaps and emerging needs, in order to guide future studies. This review is organized according to the main roles of CA, with further considerations on climate change and CA effects indicated as paramount, as strategies in the face of climate change can be crucial for species response. The literature review revealed a reduction in publications on CA over the years. In addition, a historical research differentiation is noted, where the first assessments on the subject addressed investigations on basic CA functions, while the most recent studies present a comparative approach among species as well as interdisciplinary discussions, such as ecology and phylogeny. Considering that several elasmobranchs are threatened, future studies should prioritize non-lethal methodologies, in addition to expanding studies to climate change effects on CA.

Almost nothing is known about the tiger shark in South Atlantic waters.

The tiger shark (Galeocerdo cuvier) has been relatively well assessed concerning biology and ecology aspects in both Atlantic and Pacific North America and in Caribbean waters. The amount of data in these regions has led to the species protection under capture quotas and with the creation of sanctuaries. The reality in developing countries, however, is the exact opposite, with scarce information on the species in the southern hemisphere, namely South American and African waters. In these regions, protection measures are insufficient, and studies on tiger shark biology and ecology are scarce, significantly hindering conservation and management efforts. Thus, the aim of this study was to compile scientific literature on the tiger shark in the South Atlantic and discuss the impact of these data (or lack thereof) distributed within a total of ten research categories for guiding management plans. In total, 41 scientific publications on different G. cuvier biology and ecology aspects were obtained. The most studied topics were Feeding Ecology (n = 12), followed by Human Interactions (n = 8), and Movements and Migration (n = 7). Northeastern Brazil (Southwest Atlantic) was the most researched area, probably due to the higher coastal abundance of tiger sharks in this area, alongside a high number of recorded attacks, justifying funding for studies in the region. No studies carried out in other South American or African countries were found. It is important to mention that even though some research topics are relatively well covered, a severe knowledge gap is noted for risk assessments and fisheries management, with a proposition for the implementation of sanctuaries noted. This is, however, particularly worrisome, as the South Atlantic is mostly unexplored in this regard for tiger sharks. It is also important to note how different the attention given to this species is in the North Atlantic when compared to the South region. Lastly, we highlight that the existence of sub-populations, the lack of migratory corridors geographically connecting distinct areas used by the species, and the lack of fisheries statistics on tiger shark landings, all increase the vulnerability of this species in the South Atlantic.

Unraveling Metabolite Provisioning to Offspring Through Parental Fluids: A Case Study of the Brazilian Guitarfish, Pseudobatos horkelii.

Elasmobranchs have a very distinct metabolism, and many aspects related to the energetic dynamics of these animals remain poorly investigated. The reproductive period is particularly vulnerable for viviparous species, as part of the energy reserves of the parental biomass is reallocated for gamete production and embryo development. In this context, this study aimed to characterize parental metabolite provisioning to the offspring (both sperm and developing embryos) of the Brazilian Guitarfish, Pseudobatos horkelii, through glucose, ß-hydroxybutyrate, triglycerides, and total cholesterol determinations in the uterine liquid (UL) and serum of pregnant females and in the seminal fluid (SF) and serum of males during the copulation period. No significant difference was observed for the analyzed markers between the UL and SF. Except for triglycerides, higher in female serum samples, all other energy markers were present at similar concentrations in the serum of both females and males. When comparing female UL and serum, significant differences were observed for triglycerides and total cholesterol. No differences were observed between SF and serum in males. The results indicate that all markers are being made available to offspring, possibly complementary to the yolk in the case of maternal liquid, and as an additional source for sperm mobilization required during egg fertilization in the case of the paternal fluid. Correlations between the markers in the parental matrices were also noted, compatible with the metabolic pathways activated during energy mobilization in vertebrates. Moreover, distinct marker predominance patterns were also noted for both UL and SF. Energy mobilization characterization directed to offspring through parental fluids aids in unraveling metabolic dynamics during the reproduction stage while also providing support for stress physiology studies to evaluate the indirect effects of parental allostatic overload in both sperm and developing embryos. Finally, energy mobilization assessments of parental fluids may also help elucidate how internal fertilization and viviparity evolved in this very distinct taxonomic group.

Evaluating conservation status and governmental efforts towards regional flagship species in Brazil.

Several strategies have been adopted to optimize biodiversity conservation. The use of fauna and flora species as flagships can help increase public commitment and raise funds for their conservation. However, species choices must be well balanced, considering not only intrinsic aspects (e.g., risk of extinction and ecological role), but also social, cultural, and economic aspects of the region where the flagship will be adopted. Brazil is one of the countries with the greatest diversity on the planet. Nevertheless, there are several challenges associated with natural resources conservation. Flagships have been adopted informally for decades throughout the country but there are no efforts to evaluate these strategies results for the preservation of the selected species. The aim of this study was to carry out an extensive survey on regional flagship species, their conservation status, level of endemism, and domestic legislation currently in force for their protection or human use. A total of 62 flagships were identified, with at least one species of flora and one of fauna for each of the 27 Brazilian Federative Units. The animals most commonly used as regional symbols are birds, followed by mammals. Flora species used as regional symbols are quite diverse. However, they are all somehow used by humans. As for legal protection, there are government measures for endangered species. Nevertheless, most species used as regional symbols are not at risk of extinction and, for this reason, do not receive any legal protection. Moreover, while some flagships are endemic, others are alien species, indicating that this criterion is not considered when choosing regional symbols. In the overall analysis it was noted that species choice could be optimized to highlight the national biodiversity. Despite efforts to establish legal measures for their preservation, few effective results have been observed. Therefore, improved effective measures for their conservation should be adopted to guarantee the effectiveness of flagship species for biodiversity conservation.