Trace metal biomonitoring in the farming of tambaqui (Colossoma macropomum), an Amazonian neotropical fish.

In Brazil, studies evaluating the concentration of trace metals in fish farms are scarce. Therefore, studies investigating the presence and levels of these metals in aquatic biota, particularly in fish tissues, are crucial for developing appropriate strategies to mitigate the impact of possible toxic metals. Herein, we investigated the levels of trace metals (Cr, Mn, Co, Ni, Cu, Zn, Al, Ag, Cd, Pb, Fe, Na, Mg, Ca, K, and Ba) in water, feed, and sediment, as well as the bioconcentration and bioaccumulation factors in tambaqui muscles (Colossoma macropomum). For this purpose, eight commercial fish farms, which are also engaged in other agricultural activities, were selected. Fe, Zn, Mg, and Cr concentration in tambaqui muscles exceeded the limits set by the Brazilian regulations for daily consumption by adults. Mn, Zn, Al, Pb, Fe, Na, Cu, Co, Ag, Cd, and Ba levels were substantially higher in the liver tissue of tambaquis than those in the muscle tissue. The most prevalent metals found in the feed were Ca, K, Na, Mg, and Fe. However, the levels of Cr and Cd in the sediment, as well as Pb, Mn, Cu, and Fe in the water, exceeded the maximum limits allowed by the Brazilian legislation. The highest bioconcentration factors were observed for the metals, Na, Zn, and K, with concentrations up to 4.74, 12.61, and 72.08 times, respectively, higher in tambaqui muscle compared to those in water. The bioaccumulation factors for Ca, Zn, Mg, Na, and K were 2.90, 6.96, 21.21, 212.33, and 492.02 times, respectively, higher in the muscle tissue than those in the sediment values in fishponds across all fish farms. Therefore, our findings suggest that tambaquis have a remarkable ability to bioaccumulate trace metals, particularly the essential ones, and can be categorized as a bioindicator species for environmental quality. Furthermore, we observed that, although water exhibits the highest prevalence and diversity of elements above the values recommended by the Brazilian legislation, sediment is the primary source of trace metal contamination for tambaquis.

Bioaccumulation of trace metals in Neoechinorhynchus buttnerae and in its fish host tambaqui (Colossoma macropomum) from fish farms.

Fish parasites are excellent bioindicators of environmental contamination because they respond quickly to water pollutant chemicals, and they can accumulate high concentrations of trace metals compared to their hosts. Here, we investigated the bioaccumulation pattern of the following: Cd, Ca, K, Na, Mg, Fe, Al, Zn, Ba, Mn, Cu, Pb, Cr, Ni, and Co. We investigated the presence of trace metals in the acanthocephalan parasite Neoechinorhynchus buttnerae, and the bioaccumulation factors (BAFs) of metals were tested in the food, muscle, and liver of its host fish Colossoma macropomum (tambaqui). We used samples from four commercial fish farms that also conduct other agribusiness activities. Tissues of the fish along with their parasites were subjected a trace metal concentration analysis by inductively coupled plasma optical emission spectrometry. Most of metals showed significantly higher presence in N. buttnerae than in tambaqui (p < 0.05), with increased level of Na, Pb, Ca, Mn, Zn, Al, and Fe in fish muscle and that of Cr, Ni, Zn, Al, Ca, and Ba in fish liver. Considering all the fish farms, the highest values of BAF were observed for Fe, Al, Zn, and Mn with concentrations up to 35.63, 26.88, 14.12, and 6.66 times higher in acanthocephalan tissues than in the fish muscle, respectively. Moreover, Ba, Ca, and Al showed concentrations up to 18.11, 12.18, and 11.77 times higher in acanthocephalan than in the liver of tambaqui. Our results indicate that the higher the levels of these metals in the parasite, the lower their concentrations in the muscular and hepatic tissues of the fish. Therefore, we suggest that N. buttnerae can directly influence the concentrations of trace metals in the fish tissues and accumulate both essential trace (Fe, Zn, Mn, and Ca) and toxic elements (Al, Pb, and Ba) in the host.

Parasitological assessment in hybrids Serrasalmidae fish farmed in Brazil.

This study evaluated the parasitic fauna of hybrids tambacu (Colossoma macropomum × Piaractus mesopotamicus) and patinga (P. mesopotamicus × Piaractus brachypomus) and their host-parasite-environment interaction during the warm and cold seasons in two fish farms located in the State of Mato Grosso do Sul, Brazil, South America. A total of 120 fish, being 60 fish for species (30 in the warm season and 30 in the cold season) were examined. Water quality was measured weekly to evaluate the interaction between environmental conditions and parasitism. Fifteen species of parasites were found: Ichthyophthirius multifiliis, Chilodonella hexasticha e Trichodina sp. (Protozoa), Henneguya piaractus, Myxobolus colossomatis and Myxobolus cuneus (Myxozoa); Anacanthorus penilabiatus, Mymarothecium boegeri, Mymarothecium viatorum, and Notozothecium janauachensis (Monogenoidea), Goezia spinulosa and Goezia sp. (Nematoda), Echinorhynchus jucundus (Acanthocephala), and Dolops carvalhoi, Lernaea cyprinacea (Crustacea). The ciliate protozoan I. multifiliis and monogenoids were the most prevalent parasites in the cold and warm seasons for both hybrids in the different culture systems intensive production and sportive fishing. It was observed that the serrasalmid hybrids are more susceptible to parasites and harbor high diversity of parasites in relation to the parental species C. macropomum, P. mesopotamicus and P. brachypomus, with a predominance of ectoparasites.

Atividades de vôo de operárias de Melipona seminigra (Hymenoptera: Apidae) em um sistema agroflorestal da Amazônica / Flight activities in Melipona seminigra workers (Hymenoptera: Apidae) in Amazonia

Atividades externas de vôo estão associadas a coleta de néctar, pólen, resina e barro e transporte de lixo para fora da colônia. Informações sobre esse trabalho das abelhas sem ferrão são importantes para atender a programas de manejo de polinizadores, reflorestamento e restauração ambiental e ainda a manutenção das populações silvestres destes insetos. Duas colônias de Melipona seminigra foram instaladas em um sistema agroflorestal constituído por variados tipos de espécies vegetais frutíferas e madeireiras para observações diárias de suas cargas transportadas. Um total de 17434 indivíduos foi observado sendo que 9355 (54%) transportavam pólen, 4195 (24%) resina, 2754 (16%) barro e 1130 (6%) néctar/água. O pólen foi o principal recurso coletado em ambas as colônias de junho a agosto de 2005 com pico de coleta matutino seguido por resina, barro e néctar/água, enquanto que no inicio da tarde a quantidade de cargas transportadas, em ordem decrescente, foi barro > resina > néctar/água > pólen. As temperaturas internas das colônias tiveram menor variação do que as temperaturas externas mostrando que abelhas M. seminigra também regulam a temperatura interna. Com a intensa atividade de forrageamento concluiu-se que o sistema agroflorestal pode ser uma interessante alternativa para a criação de abelhas sem ferrão.

Flight activities can be related to nectar, pollen, resin and clay collection, as well as garbage dumping to outside's hive. Information about this stingless bee work are important to attend pollinators management programs, reforest and environment recuperation with maintenance of these insects population. Four hives of Melipona seminigra were installed in an agro-forestry system with a varied assortment of wood and fruit tree species. In a total of 17434 individuals were observed 9355 (54%) of the transports were done for pollen, 4195 (24%) for resin, 2754 (16%) mud and 1130 (6%) nectar/water. Polen was the main resource collected for both colonies from June to August of 2005 with picks in the mornings, followed by resin, mud and nectar/water. Early afternoon the quantity of charges transported, in decreasing order were mud > resin > nectar/water > pollen. The internal colonies temperatures had less variation if compared to the external temperatures, showing that M. seminigra bees also regulate the internal temperature. Due to the intense flight activity in the agro-forest system is an interesting alternative to keep stingless bees in these environments.