Effect of artificial seawater and feeding frequency on the larval culture of freshwater Amazonian ornamental fish banded cichlid Heros severus (Heckel, 1840) and angelfish Pterophyllum scalare (Schultze, 1823)

The present study aimed to evaluate the effect of salinity and feeding frequency on zootechnical performance of Pterophyllum scalare and Heros severus five-day-old post-larvae. Two experiments were performed in a completely randomized experimental design in a 5 × 2 factorial scheme, with 5 different NaCl concentrations (0, 2, 4, 6 and 8 g/L) and 2 feeding frequencies (2 and 4 times a day). P. scalare showed the highest survival rates (p<0.05) when subjected to salinities of 0, 2 and 4 g/L (97.50–96.25%), and higher values (p<0.05) for standard length (13.22 mm), weight (64.64 mg) and specific growth rate (15.41% per day) when fed 4 times a day. For this species, feeding frequency did not influence survival rates. H. severus, in turn, showed higher survival rates in water without the addition of salt (96.25%) and the highest standard length in salinity of 2 g/L (11.80 mm). H. severus fed 4 times a day and presented the highest values (p<0.05) for most of the growth variables (weight: 57.28 mg, specific growth rate: 18.30% per day). The results of the present study suggest that banded cichlid post-larvae showed higher survival rates in water without salt addition, however, the best growth of this species occurred at the salinity of 2 g/L. In contrast, angelfish post-larvae can be cultivated in salinities of up to 4 g/LNaCl. A feeding frequency of 4 times per day is recommended for both species

Copepod assemblages in a highly dynamic equatorial estuary on the Brazilian Amazon Coast

14 pages, 9 figures, 1 tableThis study describes the spatial and temporal dynamics of the copepod fauna in the estuary of the Caeté River, a highly dynamic environment characterized by a unique set of hydrological and hydrodynamic attributes. This ecosystem is part of the Amazon Coastal Zone (ACZ), which sustains one of the world's largest continuous tracts of mangrove forest. In the present study, a predominance of high-energy conditions characterized by macrotides and strong tidal currents was observed throughout the year. Salinity (0.03 ± 0.05–40.00 ± 0.84) and temperatures (26.43 ± 0.10–30.08 ± 0.43 °C) were higher than during the rainy season at all sampling stations. The highest chl-a concentration (3.92 ± 1.47–17.63 ± 2.60 mg·m) was recorded at the most oligohaline (innermost) station during the rainy season, while no spatial or seasonal pattern was found in dissolved nutrient concentrations, except for phosphates, which exhibited the highest concentrations during the dry season. A total of 22 copepod taxa was identified, of which the most abundant were Oithona hebes, Oithona oswaldocruzi, Acartia tonsa, Paracalanus quasimodo, Euterpina acutifrons and Pseudodiaptomus marshi. Copepodites and nauplii were also recorded. Mean total copepod abundance varied from 710.73 ± 897 individuals (ind.)·m at the inner station to 236,486 ± 398,360 ind.·m near the mouth of the estuary (outermost station). The results reflected rainfall-influenced oscillations in hydrological variables, mainly salinity, which determined shifts in the distribution of copepods and their community structure within the study area. This pattern may be typical of estuaries in the ACZ with similar hydrodynamic and hydrological attributes that are not influenced by the Amazon River plumeThis research was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (Luci Cajuerio C. Pereira grant numbers 310909/2014-7 and 200629/2014–0, and Rauquirio Marinho da Costa grant numbers 306061/2011–2 and 200622/2014–5)Peer Reviewe

Effect of artificial seawater and feeding frequency on the larval culture of freshwater Amazonian ornamental fish banded cichlid Heros severus (Heckel, 1840) and angelfish Pterophyllum scalare (Schultze, 1823)

The present study aimed to evaluate the effect of salinity and feeding frequency on zootechnical performance of Pterophyllum scalare and Heros severus five-day-old post-larvae. Two experiments were performed in a completely randomized experimental design in a 5 × 2 factorial scheme, with 5 different NaCl concentrations (0, 2, 4, 6 and 8 g/L) and 2 feeding frequencies (2 and 4 times a day). P. scalare showed the highest survival rates (p<0.05) when subjected to salinities of 0, 2 and 4 g/L (97.50–96.25%), and higher values (p<0.05) for standard length (13.22 mm), weight (64.64 mg) and specific growth rate (15.41% per day) when fed 4 times a day. For this species, feeding frequency did not influence survival rates. H. severus, in turn, showed higher survival rates in water without the addition of salt (96.25%) and the highest standard length in salinity of 2 g/L (11.80 mm). H. severus fed 4 times a day and presented the highest values (p<0.05) for most of the growth variables (weight: 57.28 mg, specific growth rate: 18.30% per day). The results of the present study suggest that banded cichlid post-larvae showed higher survival rates in water without salt addition, however, the best growth of this species occurred at the salinity of 2 g/L. In contrast, angelfish post-larvae can be cultivated in salinities of up to 4 g/LNaCl. A feeding frequency of 4 times per day is recommended for both species

Structure and temporal variation of the phytoplankton of a macrotidal beach from the Amazon coastal zone

ABSTRACT The present study aimed to analyze the structure and the temporal variation of the phytoplankton of Ajuruteua beach (Bragança, Pará) and to investigate the influence of environmental variables on the dynamics of this community to provide a basis about the trophic state of this environment. Biological, hydrological and hydrodynamic samplings were performed during a nyctemeral cycle in the months of November/08, March/09, June/09 and September/09. We identified 110 taxa, which were distributed among the diatoms (87.3%), dinoflagellates (11.8%) and cyanobacteria (0.9%), with the predominance of neritic species, followed by the tychoplankton species. Chlorophyll-a concentrations were the highest during the rainy period (24.5 mg m-3), whereas total phytoplankton density was higher in the dry period (1,255 x 103 cell L-1). However, phytoflagellates density was significantly higher during the rainy period. Cluster Analysis revealed the formation of four groups, which were influenced by the monthly differences in the environmental variables. The Principal Component Analysis indicated salinity and chlorophyll-a as the main variables that explained the components. Spearman correlation analysis supported the influence of these variables on the local phytoplankton community. Overall, the results obtained suggest that rainfall and strong local hydrodynamics play an important role in the dynamic of the phytoplankton of Ajuruteua beach, by influencing both environmental and biological variables

Dinâmica socioambiental na Vila dos Pescadores (Amazônia Oriental, Pará, Brasil)

This study describes the social, economic and environmental aspects of a fishing community “Vila dos Pescadores” situated in the Caeté River Estuary, northeastern Pará (Brazil). The methodology adopted in this study was based on interviews, questionnaires and direct observations to characterize some social, economic and environmental aspects and on monitored of beach profile to know the local coastal dynamic. Results show that the majority of the interviewed are between 18-35 years (50.97%), are fishermen (62.13%), married (68.93%), with elementary school not completed (77.67%), live with the family (2-4 persons, 39.85%) in their own houses (86.89%) and earn monthly less than one salary (95.63%). The majority of the people has been living in the village for 10 years or more (42.71%) and do not like their current social, economic and environmental situation. The village has someenvironmental problems such as coastal erosion and serious service and infrastructure problems (e.g. little or total absence of public transports, public telephones, garbage collectors, public illumination, drinking water, basic sanitary facilities, underdeveloped commercial area, sport area, health post, police post, car parking, lifeguard, school, among others). The absence of employment opportunities is another problem, being the fisheries the main source of income in the village. On the other hand, the exuberant nature, the equatorial weather, the tranquility and the large amount of fish are the main positive aspects according to the opinion of those interviewed