RESUMO
Introduction: Hydroelectric dams have several impacts on migratory fish, such as decreasing their abundance, local extinctions, and changes in the assemblage structure. Objective: To investigate the trophic and reproductive strategies of Leporinus piau upstream and downstream from a hydroelectric dam in the Parnaíba River. Methods: We identified food items and calculated trophic niche breadth in both sites to characterize the feeding strategy. We conducted permutational multivariate analysis of variance (PERMANOVA) to determine differences in diet between sites, followed by a SIMPER analysis in order to show which items were the most dissimilar. To characterize the reproductive strategy, we analyzed weight/length relationship, body condition factor, gonadosomatic index, and size at first maturity. Results: Leporinus piau was classified as an omnivore with a predominantly plant-based diet at both sites. The diet and niche breadth varied between sites. The condition factor differed between sites while size at first maturity differed between sites and sexes. Conclusions: Leporinus piauvariations upstream and downstream from a hydroelectric dam in the Parnaíba River are results of differences in life histories traits, as identified in the life history theory, which clarifies the differences on trophic and reproductive strategies.
Introducción: Los embalses hidroeléctricos tienen varios impactos en los peces migratorios, como la disminución de su abundancia, extinciones locales y cambios en la estructura del ensamblaje. Objetivo: Investigar las estrategias tróficas y reproductivas de Leporinus piau en aguas arriba y aguas abajo de un embalse hidroeléctrico en el río Parnaíba. Métodos: Para caracterizar la estrategia de alimentación, identificamos los alimentos consumidos y calculamos la amplitud del nicho trófico en ambos sitios. Para determinar diferencias en la dieta entre los sitios, realizamos un análisis Permutacional Multivariado de Varianza (PERMANOVA), seguido de un análisis SIMPER para mostrar cuales elementos generaron las diferencias. Para caracterizar la estrategia reproductiva, analizamos relación longitud/peso, factor de condición, índice gonadosomático y talla en la primera madurez. Resultados: Leporinus piau se clasificó como omnívoro con una dieta predominantemente de origen vegetal en ambos sitios. La dieta y la amplitud de nicho variaron entre sitios. El factor de condición difirió entre sitios mientras que la talla en la primera madurez difirió entre sitios y sexos. Conclusiones: Las variaciones de Leporinus piau aguas arriba y aguas abajo del embalse hidroeléctrico en el río Parnaíba, son resultado de diferencias en los rasgos de historias de vida, como es propuesto en la teoría de historia de vida que aclara las diferencias en las estrategias tróficas y reproductivas.
RESUMO
This study aims to identify, classify, quantify the ingested microplastic by marine teleost fish, in order to analyze the relationship between microplastic and trophic guilds. Food items of 214 individuals of Opisthonema oglinum, Bagre marinus, Cathorops spixii, Sciades herzbergii, Chloroscombrus chrysurus, Conodon nobilis, Haemulopsis corvinaeformis were analyzed. The species were classified according to their trophic guilds (zoobenthivorous or opportunistic/omnivorous). All species ingested microplastic and contamination occurred independently of the trophic guild. Of the sampled fish, 55% were contaminated by microplastic. The most consumed categories were blue (28%) and transparent filaments (20%). Raman spectroscopy measurements detected that most sampled filament corresponds to blue synthetic fiber (polyester). This study can contribute by filling gaps in knowledge regarding sandy beach impacts, which are environments so highly threatened by human activities around the world and are neglected in terms of use and conservation plans.
