Latin american journal of aquatic research vol. 50 num. 5 lang. en
- Reproductive dynamics of Peprilus medius captured in the Ecuadorian Pacificel enero 26, 2023 a las 10:30 pm
ABSTRACT. In Ecuador, Peprilus medius is an important fishery resource whose destination is for local consumption and export. There are few local studies on its reproductive biology, and its capture is not regulated. Therefore, this study evaluates the most relevant aspects of its reproductive activity. Samples were obtained monthly from January to December 2017 from the capture of the purse seine fleet and the artisanal gillnet fleet landing near Manta. The morphometric analysis included the length-weight relationship, estimated using the allometry equation. The size at sexual maturity is based on the L50 criterion; the reproductive cycle was determined according to the monthly analyses of the gonadosomatic index (GSI), hepatosomatic index (HSI), and relative condition factor (Kn). A total of 334 specimens were analyzed, with average sizes of 22.0, 21.87, and 21.91 cm of total length (TL), for males, females, and combined sexes, respectively. Sex ratio was 1.17M: 1F (P > 0.05), while the length-weight relationship showed negative allometric growth for both males and females (b = 2.58; CI95% 2.48-2.72). Size at sexual maturity L50 was estimated at 21.84 and 21.23 cm TL for males and females, respectively. The GSI and HSI values and Kn showed significant differences among months (P < 0.05), with a marked seasonality during the single reproductive period. Mean size at first capture of 21 cm TL is recommended.
- New records of elasmobranchs (Vertebrata: Elasmobranchii) from the southwestern Gulf of Mexicoel enero 26, 2023 a las 10:30 pm
ABSTRACT. We present information about new records of 11 species of chondrichthyans in the southern Gulf of Mexico, adding information about new specimens and occurrence of the species in Mexican waters. The second record of the Bathytoshia centroura, Mustelus sinusmexicanus, Mobula hypostoma and Squalus clarkae species for Mexico is presented, as well as new records in marine areas and the Lagoon Alvarado system corresponding to Hexanchus vitulus, Heptranchrias perlo, Scyliorhinus retifer and Squalus cubensis. In this paper increase the number of records for species of elasmobranchs to the southwestern region of the Gulf of Mexico, increase the distribution range and knowledge about the chondrichthyofauna of Mexico.
- Effects of temperature, pH, and photoperiod on the performance of a freshwater cladoceran Moina micrura culture enriched with Lysinibacillus fusiformis and Bacillus pocheonensisel enero 26, 2023 a las 10:30 pm
ABSTRACT. The freshwater cladoceran Moina micrura has tremendous potential for mass culture as a live feed for larviculture. This study aimed to evaluate the efficacy of probiotics Lysinibacillus fusiformis A1 and Bacillus pocheonensis S2 in enhancing the population density, growth rate, and production of M. micrura under different environmental conditions. Four different temperatures (15, 20, 25, and 30°C), pH levels (4, 6, 8, and 10), and photoperiods (4L:20D, 6L:18D, 8L:16D, and 12L:12D) were set up. The daily number of individuals incubated under each environmental parameter was monitored for 12 days to determine the population density and growth rate of M. micrura. Meanwhile, the daily number of neonates from five females kept under respective environmental parameters was monitored until they died naturally. Probiotics were added individually at 5×104 CFU mL-1 twice during the first and sixth days of the experiment. M. micrura enriched with B. pocheonensis S2 at 30°C had the highest maximum population density (10 ± 0.2 ind mL-1) and the number of neonates produced (132 ± 6.43 ind), whereas treatment at 20°C had the best growth rate (0.1863 ± 0.006 d-1). M. micrura incubated with B. pocheonensis S2 at a normal photoperiod of 12L:12D had the highest maximum population density (10 ± 0.3 ind mL-1) and the number of neonates produced (129 ± 4.58 ind) while incubation at 8L:16D had the best growth rate (0.2879 ± 0.0007 d-1). M. micrura enriched with L. fusiformis A1 at pH 8 had the highest maximum population density (11 ± 0.8 ind mL-1), growth rate (0.5508 ± 0.04 d-1), and the number of neonates produced (129 ± 4.36 ind). Results recommend that a warmer temperature of 30°C, alkaline pH from 8 to 10, and a normal photoperiod of 12L:12D can be adopted for M. micrura enrichment with B. pocheonensis S2 to maximize its productivity for aquaculture use.
- New records of nematodes from three aquatic mammals in Mexico with notes about the nematode fauna recorded in Mexican watersel enero 26, 2023 a las 10:30 pm
ABSTRACT. Nematodes are among the most common parasites in aquatic mammals. Because of their cuticular covering, these worms are frequently collected from the examination of feces or stranded hosts. This work provides new records of three nematode taxa infecting three different aquatic mammal species (Lontra longicaudis annectens, Trichechus manatus, and Zalophus californianus) in Mexico. Additionally, it brings together all available published records about this country's nematode fauna parasitizing aquatic mammals. The aim is to describe the current state of the art, which sets the basis for the strategic design of future research. Given the diversity of printed sources recording nematode fauna, we gathered literature, including theses and articles in journals profiled in the Journal Citation Reports or similar academic databases. The compiled information shows that 24 nominal nematode taxa have been reported from 11 species of aquatic mammals in Mexico. Our study exhibits irregular patterns of geographic distribution and host spectrum, existing entire marine ecoregions, and numerous host species lacking records.
- Two-year monitoring of enterovirus and rotavirus A in recreational freshwater from an island region, Pará State, northern Brazilel enero 26, 2023 a las 10:30 pm
ABSTRACT. Enteric viruses are major causes of waterborne diseases and are present in large quantities in the stools of infected individuals. Its viability in the environment lasts for months, favoring the contamination of water used for consumption and recreation. The study aimed to monitor monthly the circulation of enterovirus (EV) and group A rotavirus (RVA) in recreational freshwater from an island region used as a bathhouse in northern Brazil, from January 2012 to December 2013. The viral RNA was obtained using guanidine isothiocyanate/silica after viral concentration by adsorption-elution method. The molecular detection was carried out by semi (EV) and nested-PCR (RVA) and the amplicons were sequenced on automated sequencer. At least one of these viruses was detected on 40.4% (42/104) of the samples. RVA was the most frequent (n = 32; 30.8%) when compared to EV (n = 20; 19.2%). Co-circulation between both was identified in 9.6% (n = 10). The highest viral positivity was found in SP02 (46.1%). The highest viral positivity was observed during high tides (57.7%; 60/104). Most EV samples were characterized as coxsackievirus (CV) A5 (85.7%, 12/14) and others as Sabin 1 poliovirus (14.2%, 2/14). The RVA positive samples were genotyped as G2, G3, G9, G12, P, P, and P. These viruses were detected in 35.6% (37/104) of the samples with an acceptable concentration of fecal coliform bacteria. These results demonstrate the contamination of surface water intended for recreation by enteric viruses of Public Health concern even when bacterial indicators are within the tolerated limit, a factor that confirms the need for public policies aimed the sewage treatment before its release into water bodies.