Consumer-driven nutrient recycling of freshwater decapods: Linking ecological theories and application in integrated multitrophic aquaculture.

The Metabolic Theory of Ecology (MTE) and the Ecological Stoichiometry Theory (EST) are central and complementary in the consumer-driven recycling conceptual basis. The understanding of physiological processes of organisms is essential to explore and predict nutrient recycling behavior, and to design integrated productive systems that efficiently use the nutrient inputs through an adjusted mass balance. We fed with fish-feed three species of decapods (prawn, anomuran, crab) from different families and with aquacultural potential to explore the animal-mediated nutrient dynamic and its applicability in productive systems. We tested whether body mass, body elemental content, and feeds predict N and P excretion rates and ratios within taxa. We also verified if body content scales allometrically with body mass within taxa. Finally, we compared the nutrient excretion rates and body elemental content among taxa. N excretion rates of prawns and anomurans were negatively related to body mass, emphasizing the importance of MTE. Feed interacted with body mass to explain P excretion of anomurans and N excretion of crabs. Body C:N content positively scaled with body mass in prawns and crabs. Among taxa, prawns mineralised more N and N:P, and less P, and exhibited higher N and C body content (and lower C:N) than the other decapods. Body P and N:P content were different among all species. Body content and body mass were the main factors that explained the differences among taxa and influence the role of crustaceans as nutrient recyclers. These features should be considered to select complementary species that efficiently use feed resources. Prawns need more protein in feed and might be integrated with fish of higher N-requirements, in contrast to crabs and anomurans. Our study contributed to the background of MTE and EST through empirical data obtained from decapods and it provided insightful information to achieve more efficient aquaculture integration systems.

Cultural and Religious/Spiritual Beliefs and the Impact on Health that Fear to Death has on Gender and Age, Among a Romani Minority Group from Southern Spain.

The Romani cultural minority living in Spain has cultural values and beliefs, religious/spiritual expressions and a particular vision of death. The relationship between these aspects and health is unknown. A sample of 150 people responded to a socio-demographic questionnaire and well-being measures of religious/spiritual experience, paranormal beliefs and fear of death. Age, a negative sense of life, fear of the death of others, being a woman and having low paranormal beliefs have a negative impact on health. Results allow for extending the relationships found in the general population to the Romani population as well. The novelty is that, in the latter, paranormal beliefs protect against disease. Additionally, fear of the death of others damages health more than fear of one's own death. These results make sense in the context of the Romani culture and religion.