In this work, the chronic toxicity of a mixture of light-stick chemicals and water was tested. The light-stick is used in fishery activities to catch swordfish. The tubes were collected on the beaches of the Costa dos Coqueiros -BA, Brazil, in the period from 14th to 31st July 2007. The method used was a short chronic toxicity test where embryos of the sea urchins Echinometra lucunter and Lytechinus variegatus were exposed to a stock solution consisting of the supernatant formed from a mixture of sea water and the orange-colored light-stick chemical. After a preliminary test, concentrations defined were 0.002, 0.003, 0.01, 0.02, 0.1, 1.0% of stock solution. The final test ran for 36 hours for E. Lucunter and 24 hours for L. variegatus with 4 replicates for each concentration. The value of EC50 -36h was 0.062% with confidence limits ranging from 0.042 to 0.079% and the EC50 -24h was 0.011% with confidence limits ranging from 0.009 to 0.014%, i.e., the chemical mix present in the light-stick is potentially toxic. So, as these flags are commonly used for fishing there is potential danger in their disposal in the open ocean. RESUMOO objetivo deste trabalho foi avaliar a toxicidade crônica da água do mar em contato com o líquido contido no light-stick, sinalizador utilizado em pesca de espinhel de superfície para a captura de espadarte. Os tubos foram coletados nas praias da Costa dos Coqueiros -BA, no período de 14 a 31 de Julho de 2007. O método utilizado para a verificação da toxicidade crônica foi o teste de curta duração com embriões de ouriço-do-mar Echinometra lucunter e Lytechinus variegatus, os ensaios foram realizados com solução estoque que consiste do sobrenadante formado a partir de uma mistura de água do mar com o líquido do sinalizador de coloração laranja. Após um teste preliminar as concentrações definidas foram 0.002; 0.003; 0.01; 0.02; 0.1; 1.0%. O teste definitivo teve duração de 36 horas para E. lucunter e 24 horas para L. variegatus, sendo preparadas 4 réplicas para cada concentração. O valor da CE50 -36h encontrado foi de 0.062% com limites de aceitabilidade variando de 0.042 a 0.079% e a CE50 -24h encontrada foi de 0.011% com limites de aceitabilidade variando de 0.009 a 0.014%, ou seja, os compostos químicos presentes no light-stick são potencialmente tóxicos. Portanto já que esses sinalizadores são utilizados comumente como petrechos de pesca há a necessidade de que eles sejam recolhidos, pois podem causar efeitos adversos quando abrem nos oceanos.
The genera Dissodactylus and Clypeasterophilus are commensal or parasitic crabs that live in association with irregular sea urchins. Only a single pinnotherid species is expected to occur on a sand dollar; however, during field observations, D. crinitichelis and Clypeasterophilus stebbingi were found co-occurring on a single host (Clypeaster subdepressus). Laboratory experiments and in situ observations were conducted to explore mechanisms of host selection and use by C. stebbingi, as well as the possibility of competition with D. crinitichelis. Analysis of 213 specimens of Encope emarginata and 33 C. subdepressus revealed a high frequency of infestation (90 %) by brachyurans. The number of D. crinitichelis was positively correlated with the size of E. emarginata. During field observations and experiments, D. crinitichelis was able to colonize both echinoids, while C. stebbingi was found mainly on C. subdepressus. No exclusion was reported between individuals of the same sex for both crab species. However, D. crinitichelis may be territorial, since a single male occurred when adult females were added to the host. D. crinitichelis and C. stebbingi co-occurred on the same individual of C. subdepressus on rare occasions during field observations. C. stebbingi may exclude D. crinitichelis from the echinoid to avoid competition, as observed during the experiments. We suggest a species-specific association between C. stebbingi and C. subdepressus, while D. crinitichelis associated mainly with E. emarginata, but also with C. subdepressus. Both crabs may harm the echinoids by consuming their spines, but additional research is necessary to determine whether this is a parasitic association.
From the southwestern termination of the Agulhas current, anticyclonic eddies are emitted and drift across the South Atlantic Ocean. This study is based on a FORSA (Following Ocean Rings in the South Atlantic) oceanographic cruise, from Cape Town (South AFRica) to Arraial do Cabo (Brazil) in June 2015, during which three eddies of different ages (E1, 7 months; E3, 11 months; E5, 24 months) from the Agulhas current were sampled for microplankton identification and determination of functional traits. The stations where sampling occurred at each eddy included a control outside the eddy and three stations inside the eddy—border, midway (between the border and center), and center (identified through satellite images of sea level anomaly—SLA). Functional traits were determined based on microscopic observations and consultation of the literature. An evident decay in the Agulhas eddies toward the west was observed, and each eddy proved to be different. E1 represented a younger and more robust structure. At the same time, the other eddies, E3 and E5, were more alike with similar physical, chemical, and ecological characteristics and almost the same indices values of functional diversity, demonstrating that although their species compositions were different, the strategies used by the species were the same. The most crucial ecological trait for microplankton was nutrition mode. The microplankton contained mainly mixotrophic dinoflagellates and cyanobacteria adapted to oligotrophic conditions. The functional strategy of microplankton did not differ among the eddies and stations, with mixotrophy being the most striking trait. Therefore, the older eddies’ microplankton community fits the neutrality theory, whereby species perform similar ecological functions, and the younger eddy fits in the niche complementarity. Even with the species composition being different in each eddy and/or within the same eddy, the functional strategy was the same, with scarce resources and species selected that best use any source of nutrients or use evolutionary advantages to live in an oligotrophic environment.
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