Temperature effects on the early ontogenetic stages of the intertidal stone crab Xantho poressa (Olivi, 1792)

Temperature is a well-known environmental factor that affects the survival rate and development times of larvae in many brachyuran species. Intertidal species, such as the stone crab Xantho poressa are subject to aquatic and aerial temperature conditions, which make them suitable model species to analyse the effects of climate change. In this study, we analyse the effects of temperature on the duration of embryonic and larval development, as well as larval survival, of X. poressa under laboratory conditions. For brood incubation times, 18 ovigerous females were maintained at three different constant temperatures (17, 21 and 25 °C) in seawater (salinity of 35) until hatching. The larvae from other three ovigerous females were reared individually at the same temperature and in the same salinity conditions as for the brood incubation experiments. Embryonic incubation times decreased as temperature increased. Mean incubation times ranged between 23 and 9 days at 17 and 25 °C, respectively. Larvae development was completed at the three temperatures tested with the highest survival rate occurring at 25 °C. The duration of larval development also decreased with increasing temperature. The mean number of days from hatching to the megalopa stage ranged between 35 (17 °C) and 15 days (25 °C). An additional zoeal stage (ZV) was observed at the lowest temperature tested (17 °C).The Universidad Simón Bolívar and the Asociación Universitaria Iberoamericana de Posgrado (AUIP) granted a PhD scholarship to Nebis Navarro

Population structure of the stone crab Xantho poressa (Olivi, 1972) in a human restricted access area

The stone crab Xantho poressa, is an intertidal species that inhabits the Gulf of Cadiz (GoC), the Mediterranean Sea, the Black Sea and the Canary Islands. In the GoC, this crab inhabits hiding under boulders of rocky beaches, but little information exists regarding its population. The main objective of this research was to analyse the population structure of X. poressa in an intertidal rocky shore beach with restricted access (Torregorda beach, SW Spain). A total of 190 boulders were analysed monthly from March 2019 and February 2020. In the field, individuals of X. poressa were sexed and crab size was measured using the carapace width (CW). Accompanying fauna and boulder information (location, size, and weight) were also collected. A total of 1386 individuals were analysed during the studied year (667 females, 411 males, 269 juveniles and 39 undefined individuals). The overall sex ratio differed from the 1:1 assumption on each month (except in December 2019), and seasonally. The size of adult males and females showed significant difference (p < 0.05) and varied from 11.54 to 38.19 mm CW (20.17 ± 5.08 mm), and 10.12 to 28.08 mm CW (16.22 ± 3.39 mm) respectively. The modal class for females was 14 – 16 mm CW and 20 – 22 mm CW for males. Multivariate analysis showed that X. poressa distribution in the intertidal shore seems to be mainly determined by the weight of the boulder. The frequent coexistence of a male and various females under a boulder should explain the female-biased sex ratio observed in this study which was previously suggested in another beach of the GoC.We thank the Spanish Ministry of Defence, INTA, A. Moreno, D. Roque, Universidad Simón Bolívar and the AUIP for their support in this research

The effects of temperature on embryonic and larval development of the stone crab Xantho poressa (Decapoda, Brachyura)

XX Iberian Symposium on Marine Biology Studies (SIEBM XX) , Braga, Portugal, 9 Sep - 12 Sep, 2019.Temperature is known to largely influence survival and the total duration of larval development in many brachyuran species (Anger, 2001). Animals in the intertidal zone are subject to environmental challenges posed by both aquatic and aerial climatic regimes, and thus intertidal crabs are model species for the effect of climate change (Helmuth et al., 2006). Previous investigations on a number of crab species highlight that temperature has an effect on the survival and development time of larvae (Marco-Herrero et al., 2016). However, the information on the influence of temperature on survival, growth and variability of the number of larval instars in Brachyura is limited. The aim of this research was to analyse the effects of temperature, on the duration of embryonic development, and survival and duration of larval development of X. poressa.Peer reviewe

Population structure of the stone crab Xantho poressa (Olivi, 1792) in a human-restricted access area

Some of the elements in the rocky intertidal zone, such as boulders, act as a refuge, mating, feeding and nursery area for marine fauna. In the present study, we analysed the population structure of the intertidal stone crab Xantho poressa in a human-restricted area, between March 2019 and February 2020, comprised of a rocky shore along the SW Atlantic Spanish coast. The study aims to provide information about the size distribution and identify which environmental factors shape the distribution, sex ratio and mating system of the species. The males were significantly larger than the females and no significant difference in size was observed between ovigerous and non-ovigerous females. The sex ratio was biased towards females. Groups constituted by one large male and several females were observed coexisting under a boulder. Other groups of two or more males and various females were also observed during the study. The distribution of the species is mainly determined by the size and weight of the boulder. The complexity of the study area, and the key role of boulders in the distribution of the species, suggests that X. poressa might have a refuge–defence polygynous mating system.The Universidad Simón Bolívar and the Asociación Universitaria Iberoamericana de Posgrado (AUIP), Spain granted a PhD scholarship to Nebis Navarro.Peer reviewe

Cytotoxic and genotoxic effects in mechanics occupationally exposed to diesel engine exhaust

Diesel engine exhaust (DEE), which is the product of diesel combustion, is considered carcinogenic in humans. It comprises toxic gases, polycyclic aromatic hydrocarbons (PAHs) and particulate matter which can reach the pulmonary parenchyma and trigger various diseases, including cancer. The aim of the present study was to evaluate the potential cytotoxic and genotoxic effects of DEE exposure on peripheral blood and buccal epithelial cells in mechanics occupationally exposed to DEE. We recruited 120 exposed mechanics and 100 non-exposed control individuals. Significant differences were observed between the two groups in terms of percentage of tail DNA and damage index (DI) in the alkaline comet assay; levels of biomarkers by cytokinesis-block micronucleus cytome (CBMN-Cyt) assay; frequency of micronucleus (MN), nucleoplasmic bridge (NPB), nuclear bud (NBUD) and apoptotic cells (APOP) and levels of biomarkers for micronucleus, karyorrhexis (KRX), karyolysis (KRL) and condensed chromatin (CC) by the buccal micronucleus cytome (BM-Cyt) assay. A significant and positive correlation was found between the frequency of MN in lymphocytes and buccal cells in the exposed group. Also, there was a significant correlation between age and percentage of tail DNA and DI in the comet assay, APOP and MN in the CBMN-Cyt assay and NBUD and MN in the BM-Cyt assay. Additionally, we found a positive and significant correlation of MN frequency in lymphocytes and buccal cells and age and MN frequency in lymphocytes with the time of service (years). Regarding lifestyle-related factors, a significant correlation was observed between meat and vitamin consumption and NBUD formation on CBMN-Cyt and between meat consumption and MN formation on CBMN-Cyt. Of the BM-Cyt biomarkers, there was a correlation between alcohol consumption and NBUD formation and between binucleated cell (BN), pyknosis (PYC), CC and KRL occurrence and family cancer history. These results are the first data in Colombia on the cytotoxic and genotoxic effects induced by continuous exposure to DEE and thus showed the usefulness of biomarkers of the comet, CBMN-Cyt and BM-Cyt assays for human biomonitoring and evaluation of cancer risk in the exposed populations