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The role of temperature and salinity on Paracentrotus lividus aquaculture: determination of threshold values for cultivation
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Abstract(s)
O ouriço-do-mar púrpura europeu Paracentrotus lividus (Lamarck, 1816) é uma espécie abundante nas costas rochosas de Portugal. As colheitas regulares de ouriço-do-mar para a indústria alimentar aumentaram consideravelmente em Portugal nos últimos anos, devido ao elevado valor económico das suas ovas, o que sem regulamentação apropriada pode levar a uma sobrexploração das populações naturais. A definição de um plano de gestão sustentável requer conhecimentos de base acerca da resposta da população a diferentes condições ambientais, o que é particularmente importante no contexto das alterações climáticas, uma vez que o aumento das temperaturas pode afetar o metabolismo dos organismos ectotérmicos. Por outro lado, o desenvolvimento de sistemas de produção em aquacultura eficientes para a produção de P. lividus poderá contribuir para uma diminuição da pressão sobre os stocks naturais.
Neste estudo, foi avaliado o desempenho de adultos de ouriço-do-mar europeu, considerando o índice de atividade, mortalidade, crescimento, concentração de proteínas e atividade de GST (Glutathione-S-transferase), em seis salinidades constantes (de 10 a 35) num primeiro ensaio experimental, e, num segundo ensaio, em seis temperaturas constantes (de 18ºC a 28ºC). Para alcançar os objetivos, foram feitas observações regulares durante o ensaio (12h) ao longo de 168h para o ensaio da salinidade e de 204h para o ensaio da temperatura e, no final, avaliados parâmetros biométricos, concentração de proteínas e do biomarcador de stress oxidativo (atividade de GST).
No ensaio de salinidade observou-se que os tratamentos com salinidade mais baixa (10, 15 e 20) apresentaram valores mais baixos do índice de atividade e valores de mortalidade mais elevados do que nos tratamentos com salinidade mais elevada (25, 30 e 35). Os valores de Lt50 obtidos para a salinidade 10 e 20 foram de 139.42 e 146.13 horas de exposição contínua e para a salinidade 15 de 134.60 horas. Os valores de concentração de proteínas foram mais elevados nos organismos nos tratamentos de salinidade 25 e 30, semelhante ao registado nos organismos colhidos no campo.
Em relação ao teste de temperatura, os maiores valores do índice de atividade foram registados nos tratamentos a 22ºC e 24ºC, e ao longo do teste houve também respostas diferentes em relação aos tempos de observação. Neste caso, os tratamentos que apresentaram mortalidade mais elevada foram os de 26º e 28ºC, havendo, no entanto, mortalidade em todos os tratamentos no final do ensaio. Os valores Lt foram calculados para as temperaturas de 26ºC e 28ºC em que o valor Lt50 foi de 161.73 e 166.84 horas de exposição, respetivamente. O tratamento que apresentou o valor mais elevado de concentração de proteínas foi a temperatura de 22ºC, que foi maior do que o valor encontrado nos organismos recolhidos no campo. O registo da atividade do GST foi mais elevado nas temperaturas de 18ºC e 20ºC, o valor obtido para os organismos recolhidos no campo foi semelhante ao encontrado nos organismos no tratamento da temperatura de 22ºC.
De uma forma geral, P. lividus responde melhor a salinidades mais elevadas, sofrendo maior impacto de salinidades baixas, a apresenta uma melhor performance a 22ºC, sofrendo impactos significativos a temperaturas mais elevadas (> 26ºC).
The European purple sea urchin Paracentrotus lividus (Lamarck, 1816) is an abundant species on the rocky coasts of Portugal. The regular harvesting of sea urchins for the food industry has increased considerably in Portugal in recent years, due to the high economic value of their roe, which without appropriate regulation may lead to a depletion of natural populations. The definition of a sustainable management plan requires basic knowledge about the response of the population to different environmental conditions, which is particularly important in the context of climate change, since rising temperatures can affect the metabolism of ectothermic organisms. On the other hand, the development of efficient aquaculture production systems could contribute to a decrease in the pressure on natural stocks. In this study, the performance of the adults european sea urchin was investigated, assessing activity index, mortality, growth, protein concentration, and GST activity under six distinct salinity treatments (10 to 35), in a first experimental assay, and under six temperature treatments (18ºC to 28ºC), in a second assay. To achieve our objectives, observations were made every 12 h, over 168h for the salinity assay and 204h for the temperature assay and at the end of the assays biometric parameters, protein concentration and oxidative stress biomarker (GST activity) were evaluated. In the salinity test it was observed that the treatments with lower salinity (10, 15 and 20) showed lower values of the activity index and higher mortality values than the treatments with higher salinity (25, 30 and 35). The Lt50 values obtained for salinity 10 and 20 were 139.42 and 146.13 hours of continuous exposure and for salinity 15 the 134.60 hours. Protein concentration values were higher in organisms in salinity treatments 25 and 30, similar to that recorded in organisms collected in the field. Regarding the temperature test, the highest values of the activity index were recorded in the treatments at 22ºC and 24ºC, and throughout the test there were also different responses regarding observation times. In this case, the treatments that presented the highest mortality were those at 26ºC and 28ºC. However, there was mortality in all treatments at the end of the test. Lt values were calculated for the temperatures of 26ºC and 28ºC where Lt50 value was 161.73 and 166.84 hours of exposure, respectively. The treatment that presented the highest value of protein concentration was the temperature of 22ºC, which was higher than the value found in the organisms collected in the field. The record of GST activity was higher in the temperatures of 18ºC and 20ºC, the value obtained for the organisms collected in the field was similar to that found in the organisms in the 22ºC temperature treatment. In general, P. lividus responds better to higher salinities, suffering greater impact at low salinities, and performs better at 22ºC, suffering significant impact at higher temperatures (> 26ºC).
The European purple sea urchin Paracentrotus lividus (Lamarck, 1816) is an abundant species on the rocky coasts of Portugal. The regular harvesting of sea urchins for the food industry has increased considerably in Portugal in recent years, due to the high economic value of their roe, which without appropriate regulation may lead to a depletion of natural populations. The definition of a sustainable management plan requires basic knowledge about the response of the population to different environmental conditions, which is particularly important in the context of climate change, since rising temperatures can affect the metabolism of ectothermic organisms. On the other hand, the development of efficient aquaculture production systems could contribute to a decrease in the pressure on natural stocks. In this study, the performance of the adults european sea urchin was investigated, assessing activity index, mortality, growth, protein concentration, and GST activity under six distinct salinity treatments (10 to 35), in a first experimental assay, and under six temperature treatments (18ºC to 28ºC), in a second assay. To achieve our objectives, observations were made every 12 h, over 168h for the salinity assay and 204h for the temperature assay and at the end of the assays biometric parameters, protein concentration and oxidative stress biomarker (GST activity) were evaluated. In the salinity test it was observed that the treatments with lower salinity (10, 15 and 20) showed lower values of the activity index and higher mortality values than the treatments with higher salinity (25, 30 and 35). The Lt50 values obtained for salinity 10 and 20 were 139.42 and 146.13 hours of continuous exposure and for salinity 15 the 134.60 hours. Protein concentration values were higher in organisms in salinity treatments 25 and 30, similar to that recorded in organisms collected in the field. Regarding the temperature test, the highest values of the activity index were recorded in the treatments at 22ºC and 24ºC, and throughout the test there were also different responses regarding observation times. In this case, the treatments that presented the highest mortality were those at 26ºC and 28ºC. However, there was mortality in all treatments at the end of the test. Lt values were calculated for the temperatures of 26ºC and 28ºC where Lt50 value was 161.73 and 166.84 hours of exposure, respectively. The treatment that presented the highest value of protein concentration was the temperature of 22ºC, which was higher than the value found in the organisms collected in the field. The record of GST activity was higher in the temperatures of 18ºC and 20ºC, the value obtained for the organisms collected in the field was similar to that found in the organisms in the 22ºC temperature treatment. In general, P. lividus responds better to higher salinities, suffering greater impact at low salinities, and performs better at 22ºC, suffering significant impact at higher temperatures (> 26ºC).
Description
Keywords
P. lividus Aquacultura Temperatura Salinidade Índice de atividade Tempo letal Paracentrotus lividus Aquaculture Temperature Salinity Lethal time