Recovery of ghost crabs metapopulations on urban beaches during the Covid-19 "anthropause".

The majority of government authorities initially responded to COVID-19 pandemic by declaring lockdown to facilitate social distancing and minimize virus spreading. This period termed "anthropause" provided a unique opportunity to evaluate the recovery of wildlife in the absence of stressors on urban ecosystems. We assessed whether the anthropause associated with beach closures during the COVID-19 pandemic resulted in repopulation of the Atlantic ghost crab Ocypode quadrata (Fabricius, 1787) on urban beaches. For this purpose, we compiled a historic dataset (2013-2019) of the ghost crab density and performed biweekly burrow measurements from June/2020 to May/2021. Recovery of ghost crab metapopulation during the lockdown occurred even in more human-modified beaches. Burrow abundance significantly increased in urban sectors, but not in control site along with the time of pandemic. The reduction in the mean burrow opening diameter during this period evidenced that young metapopulation have thrived on urban beaches when recreational activities ceased. Our results show that urban beaches should not be exclusively managed for recreational purposes. Initiatives with a focus on wildlife conservation including spatial-temporal controlled beach closures may increase the biodiversity resilience.

Bycatch of Asteroidea from shrimp trawl fishery in the southwestern Atlantic Ocean ­ Brazil

Shrimp trawling is considered a significant negative impact on the marine ecosystem, especially on the benthic community. Sea stars (Echinodermata: Asteroidea) are one of the most affected groups by unintentional catches. This study was performed at the Santana Archipelago, a Marine Protected Area in the northern region of Rio de Janeiro State, between 2008-2009. Sea stars accidentally caught by trawling were collected during open and closed season of the shrimp fisheries (Xiphopenaeus kroyeri) at depths of 5-60 m. A generalized linear zero-inflated model was applied to test for differences in capture between fishing seasons and depths. A total of 158 sea star specimens were captured. These specimens were identified as Asterina stellifera, Astropecten acutiradiatus, Astropecten brasiliensis, Astropecten cingulatus, Luidia alternata alternata, Luidia clathrata, Luidia ludwigi scotti, Luidia senegalensis. The sea stars A. brasiliensis and L. senegalensis are currently considered as vulnerable species in the Brazilian official list of threatened species. The higher capture of sea stars was shown in deepest areas, and there was no significant difference in the number of specimens between seasons. This is the first study about asteroids accidentally captured by shrimp trawling.(AU)

Mercury Concentrations in Four Marine Fishery Resources from Rio de Janeiro Coast, SW Atlantic, and Potential Human Health Risk Via Fish Consumption.

Mercury (Hg) contamination has caused ecological and socioeconomic problems worldwide. One of the main Hg contamination routes by the human populations is through fish ingestion. Herein, we analyzed the total Hg concentrations (THg) in highly consumed marine fish species: Brazilian flathead Percophis brasiliensis, Atlantic bigeye Priacanthus arenatus, Stripped weakfish Cynoscion guatucupa, and Jamaica weakfish C. jamaicensis. The specimens were collected from fishing landings off the Rio de Janeiro, SW Atlantic. Additionally, we calculate the estimated weekly intakes (EWI) and the maximum amount of fish (MAF) that can be safely ingested, both based on the provisional tolerable weekly intake (PTWI). The highest THg concentrations were recorded in P. brasiliensis with a mean of 340.59 µg/kg (dry weight) and the lowest in P. arenatus (115.75 µg/kg). THg concentrations were positively related to the δ15N ratios indicating an increase in contamination with trophic level. All samples showed THg concentrations below the established limits by Brazilian and international regulation. Hg intake via human fish consumption does not exceed the PTWI. The EWI varied from 1.41% (P. arenatus size class I) to 11.52% (P. brasiliensis class II) of the PTWI, while the estimated EWI for "fish consumers" varied between 8.35 and 68.07% PTWI. The MAF estimated for an adult (70 kg) could safely consume between 1277.85 and 7075.50 g/week. This study is an important baseline for monitoring and future comparisons. Therefore, it is important to maintain monitoring of mercury levels in fish species in different marine regions, especially those species most consumed by humans.

Dissecting the distribution of brittle stars along a sewage pollution gradient indicated by organic markers.

We have assessed variation in brittle star distribution patterns along a contamination gradient identified by fecal steroids and aliphatic hydrocarbons in Paranaguá Bay, southern Brazil. A hierarchical design using multiple spatial scales (centimeters-kilometers) was applied. Generalized linear mixed models (GLMMs) were used to investigate the spatial and temporal variability of brittle stars. Main principal components from the contamination and environmental matrices were used to investigate the best explanatory dataset. The abundance of brittle stars was significantly lower in sites with high concentrations of fecal steroids and aliphatic hydrocarbons. The best model fitting always included components from the contamination gradients, which precludes a purely environmental driving of brittle star abundance. Variability in spatial scales lower than kilometers was probably driven by sediment characteristics. We highlighted the importance of a robust multi-scale sampling design for a better biological indication of coastal contamination.

Is the distribution of the lancelet Branchiostoma caribaeum affected by sewage discharges? An analysis at multiple scales of variability.

Spatial variation in the density and biomass of Branchiostoma caribaeum was analyzed along a sewage contamination gradient identified by fecal steroids in a subtropical estuary, southern Brazil. Sampling, repeated in the austral winter and summer, followed a hierarchical design nested at four spatial scales (sector>1 km; area>100 m; site>10 m; replicate<1 m). Density and biomass were significantly lower at sites characterized by high concentrations of fecal steroids. The best combinations of variables that explained the biological similarities among sites involved contamination indicators. Most of the variation of biological data was found at the smallest scales and could be related with the sediment texture. Our study highlighted the usefulness of a multi-scale perspective to evaluate distribution patterns of benthic invertebrates as a biological indication of environmental pollution. Gradient analyses at larger spatial scales may be invalidated by the patchy distribution of benthic fauna if they do not account for such small scale variability.