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Variação espaço-temporal de Donax gemmula (mollusca: donacidae) em praias arenosas de Aracaju, Sergipe, nordeste do Brasil

Wed, 29 Jul 2026 00:00:00 GMT

Título: Variação espaço-temporal de Donax gemmula (mollusca: donacidae) em praias arenosas de Aracaju, Sergipe, nordeste do Brasil Autor(es): Silva, Caio Correia Régis da Abstract: Sandy beaches are highly dynamic environments that dominate continental coastlines. The genus Donax (Bivalvia: Tellinoidea: Donacidae) is one of the most common taxonomic groups on Brazilian beaches, distributed primarily in the intertidal and shallow infralittoral zones of tropical sandy shores. Donax gemmula is the smallest species of the genus in the southwestern Atlantic and was the dominant species on the beaches of Aracaju for several years. However, most ecological knowledge on this species comes from benthic macrofauna studies conducted in temperate and subtropical climates. The present study characterized the spatio-temporal variation in the abundance and maximum shell length (MSL) of D. gemmula in the swash zone of sandy beaches in Aracaju, Sergipe, northeastern Brazil, and assessed whether species abundance tracks the variation of oceanic, meteorological, and morphodynamic environmental variables in a tropical system. Eight sites along ~23 km of Aracaju's beaches were sampled bimonthly over one year (Sep/2024–Jul/2025). Specimens were identified, quantified, and measured through image thresholding. Environmental variables were measured in situ and retrieved from online databases. Spatio-temporal variation in abundance was analyzed using PERMANOVA, followed by PERMDISP and post-hoc analyses. The relationship between abundance and environmental variables was analyzed via LMMs, with date as a random factor. Environmental variables exhibited distinct temporal patterns. A total of 3,482 D. gemmula individuals were recorded. Mean abundance varied spatio-temporally, peaking in January and March, with the lowest values in May and July 2025. Spatial differences in mean abundance were detected only in January and May 2025. MSL ranged from 1.52 to 8.7 mm, with January and March showing the highest MSL values. Juveniles strongly dominated the population (96.5%). The LMM indicated a negative relationship between abundance and mean grain size. The observed abundance and size ranges fell within the values reported in the literature, contrasting with the macroecological pattern of reduction towards the tropics. Species abundance was higher in months characterized by higher temperatures, moderate flow discharge of the Sergipe River, lower oceanic chlorophyll-a (chla), and lower wave height; and was lower in months with higher accumulated rainfall. The negative association with chla contradicts the expected pattern of increased abundance with greater food availability. Overall, our findings suggest that patterns established for subtropical and temperate sandy beaches are not directly generalizable to tropical D. gemmula populations, highlighting the critical role of environmental context in driving the spatial and temporal variation of the species.

Personalidade colonial modula a toxicidade de inseticidas em cupins

Thu, 30 Jul 2026 00:00:00 GMT

Título: Personalidade colonial modula a toxicidade de inseticidas em cupins Autor(es): Pedro, Ariele de Paiva São Abstract: Animal personality can influence importante ecological processes, including responses to environmental risks. Termites are social insects of great ecological importance in tropical exosystems due to their role in nutriente cycling and the economic damage caused by some species. Studies investigating colony personality in termites are scarce, and there is currently no evidence regarding the influence of colony personality on pest management efficiency. Here, we investigated whether differences in the activity levels of Nasutitermes corniger colonies are associated with susceptibility to the insecticide imidacloprid and with contaminant transmission among colony members. Initially, colony activity profiles were characterized using Principal Component Analysis (PCA). Based on the first principal component and complementary behavioral traits, six colonies were classified as exhibiting either low- or high-activity profiles. Toxicity and horizontal transfer bioassays were subsequently conducted and analyzed using mixed-effects models. We evaluated susceptibility to imidacloprid, as well as contaminant transfer and behavioral responses among members of low- and high-activity colonies. Our results showed that low-activity colonies were less susceptible to imidacloprid, requiring a 1.84-fold higher dose to achieve the same mortality observed in high-activity colonies. However, low-activity colonies exhibited higher mortality resulting from horizontal transfer than high-activity colonies. These findings may be explained by the fact that high-activity colonies displayed more vibrational behavior and a lower frequency of social interactions following exposure, which may have limited the horizontal transfer of the insecticide. In contrast, low-activity colonies exhibited greater aggregation and a higher frequency of interindividual contacts, facilitating the spread of the insecticide among colony members. This study demonstrates that colony personality can influence contaminant exposure, susceptibility, and transmission in termites, with potential implications for colony fitness as well as for the management of these insects.

Atropelamentos de vertebrados silvestres no semiárido brasileiro: dinâmica temporal, hotspots e fatores ambientais

Mon, 20 Jul 2026 00:00:00 GMT

Título: Atropelamentos de vertebrados silvestres no semiárido brasileiro: dinâmica temporal, hotspots e fatores ambientais Autor(es): Silva, João Gabriel Santos Abstract: The road network plays an important role in the movement of people and the transportation of goods between regions of the country. However, roads are responsible for a series of negative environmental impacts, such as wildlife roadkills. In general, these roadkills occur in clustered patterns along specific road segments, known as hotspots, and may be influenced by adjacent landscape characteristics and seasonal factors, such as precipitation. Therefore, the present study analyzed wild vertebrate roadkills along a 112-km stretch of the SE-230 highway, located in a Caatinga area in the state of Sergipe, northeast of Brazil, characterizing the affected fauna, its temporal dynamics, the spatial distribution of hotspots, and the influence of landscape and precipitation on these events. Monitoring was conducted biweekly between January and December 2025 by two observers traveling in a motorized vehicle at 50 km/h, during which information regarding specimen identification, date, and geographic coordinates was recorded. Circular analyses (Rayleigh and Mardia–Watson–Wheeler tests) were used to evaluate the temporal distribution of roadkills, while Ripley’s K 2D and 2D HotSpot Identification tests were applied to identify hotspots. In addition, logistic regression models were used to investigate the influence of landscape and precipitation. A total of 524 individuals belonging to 63 vertebrate species were recorded. Amphibia showed the highest number of records (37.79%), followed by Aves (24.62%), Mammalia (24.04%), and Reptilia (13.55%). Circular analyses indicated a non-uniform distribution of roadkills for amphibians, reptiles, and mammals, whereas birds showed a uniform distribution throughout the year, with differences in the temporal distribution of roadkills among vertebrate classes. The location of hotspots varied between dry and rainy months, showing low spatial similarity among taxonomic groups. Logistic regression models indicated that landscape variables influenced roadkills as urban areas and use mosaics. Furthermore, precipitation had a positive effect on amphibians and birds. The results demonstrate that vertebrate roadkills in the Caatinga exhibit temporal and spatial variation. Thus, this study contributes to expanding knowledge about the impacts of roads in semiarid regions and provides support for the implementation of mitigation measures aimed at wildlife conservation.

Determinantes ambientais da diversidade genética da fauna marinha brasileira: uma meta-análise

Fri, 24 Jul 2026 00:00:00 GMT

Título: Determinantes ambientais da diversidade genética da fauna marinha brasileira: uma meta-análise Autor(es): Castro, Juliano Guerra de Abstract: Genetic diversity is a fundamental dimension of biodiversity, playing a key role in species evolution and in the resilience of populations to global climate change. This study aimed to conduct a systematic review of the scientific literature on population genetics of Brazilian shallow waters marine fauna and to synthesize its results using linear mixed models (LMMs) and meta-regressions, to evaluate the influence of environmental variables on genetic diversity. Studies were included if they measured, or allowed the measuring of, haplotype diversity (h) and nucleotide diversity (3,14) in at least three populations with five or more individuals of Brazilian marine species distributed along the coast and oceanic islands, based on mitochondrial molecular markers. The literature search was conducted in the Web of Science, Scopus, PubMed, and Periódicos CAPES databases on December 2, 2025, yielding 1,210 records, of which 63 were included, comprising 64 species and 375 populations. Data synthesis was performed using LMMs, including a spatial autocovariate as a fixed effect to consider the spatial dependence between populations. Results robustness to evolutionary dependence between species as assessed through phylogenetic models (pGLMMs). Model robustness to h and r precision was assessed through sensitivity analyses restricted to populations with 25 or more individuals. Risk of bias in the meta-regressions was evaluated using funnel plots, Egger’s test, Rosenthal’s Failsafe-N, and leave-one-out analyses. The LMMs revealed a weak but consistent positive effect of mean annual sea surface temperature (SST) on h (Estimate = 0.04; p = 0.001), whereas no robust effect was observed for 3,14. This pattern suggests that temperature primarily influences recent demographic events, with no evidence of detectable differences in mutation rates among environments. Meta-regressions conducted using Fisher’s Z-transformed correlation coefficients (Zr) for 40 species with four or more populations corroborated this result (Zr = 0.464; CI = 0.28–0.65; p < 0.0001). The effect was consistent across the most represented phyla and independent of the methodological approaches employed. Robustness analyses found no evidence of publication bias and supported consistency in the results. Limitations of this study include the exclusive use of mitochondrial markers, representing only a fraction of the genome, as well as taxonomic and geographic bias. Overall, the results reinforce that the phylogeographic patterns in Brazilian marine fauna genetic diversity emerge from the interaction between environmental variables, life history and evolutional processes. Therefore, more integrative conservation strategies, aided by high resolution genomic approaches, could highly benefit the understanding and preservation of Brazilian marine biodiversity.