RESUMO
Apart from the physiological impacts on marine organisms caused by ingesting microplastics, the toxicity caused by substances leaching from these particles into the environment requires investigation. To understand this potential risk, we evaluated the toxicity of virgin (raw) and beach-stranded plastic pellets to the development of embryos of Lytechinus variegatus, simulating transfers of chemical compounds to interstitial water and water column by assays of pellet-water interface and elutriate, respectively. Both assays showed that virgin pellets had toxic effects, increasing anomalous embryonic development by 58.1% and 66.5%, respectively. The toxicity of stranded pellets was lower than virgin pellets, and was observed only for pellet-water interface assay. These results show that (i) plastic pellets act as a vector of pollutants, especially for plastic additives found on virgin particles; and that (ii) the toxicity of leached chemicals from pellets depends on the exposure pathway and on the environmental compartment in which pellets accumulate.
Assuntos
Desenvolvimento Embrionário/efeitos dos fármacos , Lytechinus/efeitos dos fármacos , Plásticos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Equinodermos , Lytechinus/embriologia , Plásticos/químicaRESUMO
Este estudo avaliou as características reprodutivas de uma população do ouriçodo mar Lytechinus variegatus e a influência do ciclo lunar na liberação de gametas. Foramrealizadas oito coletas para avaliação do índice gonadossomático (IG) e dos parâmetrospopulacionais relacionados com a reprodução. Para avaliação do efeito da Lua na liberaçãode gametas foram realizadas coletas em três ciclos lunares completos. Ao todo foramcoletados 295 indivíduos, sendo 156 machos e 131 fêmeas (proporção 1,19:1), porém nãohouve diferença significativa na proporção sexual da população. O peso dos machos foisignificativamente maior que o das fêmeas, porém não houve diferença significativa no IG,peso gonadal e diâmetro entre os sexos. Com a amplitude no diâmetro dos animaiscoletados (5,5-8,7 cm) foram estabelecidas cinco classes de tamanho. Não houve diferençassignificativas no IG entre as classes de tamanho. Houve efeito da periodicidade lunar naliberação de gametas, com menor IG na lua nova, indicando que esta ocorre no primeiroquarto lunar e em marés de sizígia.(AU)
This work evaluated thespawning of sea urchin Lytechinus variegates based on lunar cycle and populationcharacteristics. Eight monthly collections were realized to estimate the gonadosomatic index(GI) and population parameters regarding reproduction. To evaluate the effect of the lunarcycle on spawning, samples were taken for each moon phase of three lunar cycles. In theentire work 295 individuals were collected, 156 males and 131 females (1.19:1 ratio).However, there was no significant difference in the sex ratio of the population. The weightof males was significantly greater than that of females. There were no differences betweenmales and females in gonadosomatic index (GI), gonad weight and diameter. There was aneffect of the lunar periodicity on spawning, with lower GI in new moon, indicating thatspawning occurs on the first lunar quarter in spring tide.(AU)
Assuntos
Animais , Lytechinus/embriologia , Lua , Células Germinativas , ReproduçãoRESUMO
The sea urchin Lytechinus variegatus is a promissory species for aquaculture activities in tropical countries. In Venezuela, this species has some economical importance but their embryonic and larval development had not been studied. We collected specimens from seagrass beds in Margarita Island (Venezuela) and kept them in the laboratory, where they spawned naturally. With filtered sea water (temperature 28 degrees C, salinity 37 psu) and moderate aeration, the eggs and sperm were mixed (relation 1:100) and reached a 90% fertilization rate. The fertilization envelope was observed after two minutes, the first cellular division after 45 minutes and the prism larval stage after 13 hours. The echinopluteus larval stage was reached after 17 hours and metamorphosis after 18 days of planktonic life, when the larvae start their benthic phase.
Assuntos
Animais , Lytechinus/embriologia , Óvulo/crescimento & desenvolvimento , Divisão Celular , Embrião não Mamífero , Fertilização , Larva , Lytechinus/crescimento & desenvolvimento , VenezuelaRESUMO
The sea urchin Lytechinus variegatus is a promissory species for aquaculture activities in tropical countries. In Venezuela, this species has some economical importance but their embryonic and larval development had not been studied. We collected specimens from seagrass beds in Margarita Island (Venezuela) and kept them in the laboratory, where they spawned naturally. With filtered sea water (temperature 28 degrees C, salinity 37 psu) and moderate aeration, the eggs and sperm were mixed (relation 1:100) and reached a 90% fertilization rate. The fertilization envelope was observed after two minutes, the first cellular division after 45 minutes and the prism larval stage after 13 hours. The echinopluteus larval stage was reached after 17 hours and metamorphosis after 18 days of planktonic life, when the larvae start their benthic phase.