Biometric relationships between body size and otolith size in 15 demersal marine fish species from the northern Brazilian coast

The relationships between fish size and sagitta otolith measurements were calculated for the first time for 15 species belonging to six families from the northern Brazilian coast. A total of 220 fish were sampled from the bycatch landed by the bottom-trawl industrial shrimp-fishing fleet between August and September 2016. All species had strong relationships between otolith measurements and fish total length with the coefficient of determination (r 2) ranging between 0.71 and 0.99. The variable most strongly related to fish total length was found to be the sagittal otolith length (OL) with 98% of the variability. These relationships are a useful tool to estimate length and mass of preyed fish from otoliths found in stomach contents of marine predators. (AU)

Anisakid larva parasitizing Plagioscion squamosissimus in Marajó Bay and Tapajós River, state of Pará, Brazil / Larva de anisaquídeo parasitando Plagioscion squamosissimus na Baía de Marajó e no Rio Tapajós, estado do Pará, Brasil

Abstract In November 2014 and May 2015, a total of 44 specimens of the South American silver croaker Plagioscion squamosissimus were collected: 30 in Marajó Bay and 14 in the Tapajós River, state of Pará, Brazil. The aim was to investigate the presence of anisakid nematodes and determine their parasitism indices and sites of infection, because of their importance regarding health inspection. Sixty-nine Anisakis sp. larvae were found; among them, 16 larvae in seven fish collected in Marajó Bay and 53 larvae in four fish in the Tapajós River. The parasitism indices of the nematodes collected from the fish in Marajó Bay comprised prevalence (P) of 23%, mean infection intensity (MI) of 2.28, mean abundance (MA) of 0.53, range of infection (RI) of 1-4, and infection site (IS) in the mesentery. The fish from the Tapajós River showed P = 28%, MI = 13.2, MA = 3.8, RI = 1-22, and IS = mesentery and intestine. To assist in taxonomic identification, images of the specimens obtained through optical microscopy with Nomarski's interferential contrast system and scanning electron microscopy were used. This is the first record of Anisakis sp. parasitizing P. squamosissimus.

Resumo Em novembro de 2014 e maio de 2015, foi coletado um total de 44 espécimes de pescada branca, Plagioscion squamosissimus, sendo 30 na Baía de Marajó e 14 no Rio Tapajós, Estado do Pará, Brasil, com o objetivo de pesquisar a presença de nematoides anisaquideos e fornecer os índices parasitários, assim como os sítios de infecção, devido a sua importância na inspeção sanitária. Encontrou-se um total de 69 larvas de Anisakis sp., sendo 16 em 7 peixes coletados da Baía de Marajó e 53 larvas em 4 peixes do Rio Tapajós. Os índices parasitários desses nematoides coletados dos peixes da Baía de Marajó apresentaram prevalência (P) de 23%, intensidade média (IM) de 2,28, abundância média (AM) de 0,53, amplitude de variação da intensidade de infecção (AI) de 1-4 e sítio de infecção (SI) o mesentério; e os do Rio Tapajós P = 28%, IM = 13,2, AM = 3,8, AI = 1-22 e SI = mesentério e intestino. Para auxiliar na identificação taxonômica foram utilizadas imagens obtidas dos espécimes por microscopia ótica com sistema de contraste interferencial de Nomarski e microscopia eletrônica de varredura. Esse é o primeiro registro de Anisakis sp. parasitando P. squamosissimus.

Spatial, seasonal and ontogenetic changes in food resource use by a piscivore fish in two Pantanal lagoons, Brazil

We evaluated the factors that affect the food resource use by Plagioscion ternetzi using three approaches: spatial, seasonal, and ontogenetic changes. Fish were sampled between March 2000 and February 2001 and March 2003 and February 2004 in the Sinhá Mariana and Chacororé lagoons, wetlands of the Pantanal Matogrossense. Fish was the predominant food in the diet, but shrimps and insects have been also consumed. The diet of P. ternetzi was significantly different between lagoons, but no difference was detected between dry and flood periods. In Sinhá Mariana lagoon, the diet mainly consisted of Psectrogaster curviventris, in both periods. In the flood period in Chacororé lagoon, fish was the dominant food (especially Astyanax spp., Leporinus spp. and Schizodon borellii), and in dry, shrimp and Eigenmannia spp. The Spearman coefficient indicated no correlation between the abundance of caught fish species and their abundances in the diet of P. ternetzi in Sinhá Mariana lagoon, and a strong negative correlation at Chacororé lagoon, although some very consumed preys were numerically abundant in the environment. Despite the intake of insect and shrimp, P. ternetzi was piscivorous since immature stages. A correlation between each item and the size classes of P. ternetzi was tested by means of Pearson correlation that showed that the changes in the use of resources over ontogenetic development have been represented by increased intake of P. curviventris in Mariana lagoon, and S. borellii at Chacororé lagoon, accompanying the increase in the size of the predator. In this way, the results suggest that several factors can be involved in the use of food resources by P. ternezi, among them the abundance, the size and morphological characteristics of the prey.

Neste estudo foram avaliados fatores que afetam o uso dos recursos alimentares por Plagioscion ternetzi, Boulenger, 1895, utilizando três abordagens: variações espacias, sazonais e ontogenéticas. Os peixes foram amostrados de fevereiro/2000 a março/2001 e de fevereiro/2003 a março/2004 nas lagoas Sinhá Mariana e Chacororé, Pantanal Matogrossense. Peixe foi o principal alimento, porém camarões e insetos também foram consumidos. A dieta de P. ternetzi foi significativamente diferente entre as lagoas, mas não diferiu entre os períodos de cheia e seca. Na lagoa Mariana, Psectrogaster curviventris foi a presa mais consumida em ambos os períodos. Na lagoa Chacororé, peixes dominaram a dieta (principalmente Astyanax spp., Leporinus spp. and Schizodon borellii) na cheia, e camarão e Eigenmannia spp. na seca. Uma correlação de Spearman mostrou que não existe correlação entre a abundância das espécies de peixes capturadas e suas abundâncias na dieta de P. ternetzi na lagoa Mariana, e que há uma correlação negativa na lagoa Chacororé, embora algumas presas importantes na dieta tenham sido numericamente importantes nas capturas. Embora tenha consumido camarões e insetos, P. ternetzi foi piscívora desde imatura. A correlação entre os itens alimentares e as classes de tamanho de P. ternetzi (Correlação de Pearson) evidenciou que as mudanças no uso do alimento durante a ontogenia estiveram associadas ao incremento no consumo de P. curviventris na lagoa Mariana, e de S. borellii na lagoa Chacororé, acompanhando o aumento de tamanho do predador. Assim, os resultados sugerem que vários fatores podem estar envolvidos no uso dos recursos alimentares por P. ternetzi, entre eles, a abundância, o tamanho e as características morfológicas das presas. .

The complete mitochondrial genome of the small yellow croaker and partitioned Bayesian analysis of Sciaenidae fish phylogeny

To understand the phylogenetic position of Larimichthys polyactis within the family Sciaenidae and the phylogeny of this family, the organization of the mitochondrial genome of small yellow croaker was determined herein. The complete, 16,470 bp long, mitochondrial genome contains 37 mitochondrial genes (13 protein-coding, 2 ribosomal RNA and 22 transfer RNA genes), as well as a control region (CR), as in other bony fishes. Comparative analysis of initiation/termination codon usage in mitochondrial protein-coding genes of Percoidei species, indicated that COI in Sciaenidae entails an ATG/AGA codon usage different from other Percoidei fishes, where absence of a typical conserved domain or motif in the control regions is common. Partitioned Bayesian analysis of 618 bp of COI sequences data were used to infer the phylogenetic relationships within the family Sciaenidae. An improvement in harmonic mean -lnL was observed when specific models and parameter estimates were assumed for partitions of the total data. The phylogenetic analyses did not support the monophyly of Otolithes, Argyrosomus, and Argyrosominae. L. polyactis was found to be most closely related to Collichthys niveatus, whereby, according to molecular systematics studies, the relationships within the subfamily Pseudosciaenidae should be reconsidered.

Plasma ion levels of freshwater and marine/estuarine teleosts from Southern Brazil

The purpose of this study was to investigate Na+, Cl-, K+, Ca2+, and Mg2+ levels in the plasma of freshwater and marine/estuarine teleosts collected at different salinities (0 to 34) from the estuarine and freshwater portions of the São Gonçalo channel in Southern Brazil. Any relationship between plasma ion levels and salinity and the capacity of ionic regulation of teleosts found at three or more different salinities (Genidens barbus and Micropogonias furnieri) was also investigated. Results showed no relationship between plasma ion levels and salinity when considering all species together, but the two species collected from three or more different salinities showed a significant positive relationship between plasma ion levels and salinity, indicating that G. barbus and M. furnieri have a high capacity to regulate plasma ion levels at both low and high salinities.

A proposta deste estudo foi investigar os níveis de Na+, Cl-, K+, Ca2+, and Mg2+ no plasma de teleósteos de água doce e marinhos/estuarinos coletados em diferentes salinidades (0 a 34) nas porções de água doce e estuarinas do Canal São Gonçalo, sul do Brasil. Uma possível relação entre os níveis iônicos plasmáticos e a salinidade também foi investigada bem como a capacidade de regulação iônica dos teleósteos coletados em três ou mais salinidades (Genidens barbus e Micropogonias furnieri). Os resultados mostraram que não houve relação entre os níveis iônicos no plasma com a salinidade quando considerando todas as espécies juntas, mas as duas espécies coletadas em três ou mais salinidades mostraram uma relação significativamente positiva entre níveis iônicos no plasma e salinidade, mostrando que G. barbus e M. furnieri apresentaram uma grande capacidade para regular os íons do plasma em baixas e altas salinidades.

Demersal ichthyofauna of the inner continental shelf off Ilhéus, Bahia, Brazil / Ictiofauna demersal da plataforma continental interna ao largo de Ilhéus, Bahia, Brasil

We present an inventory of demersal fishes from the inner continental shelf off Ilhéus, Bahia, Brazil. Three sites were sampled monthly, between March 2003 and February 2005, with standardized bottom trawls (30 minutes, 16 m depth, 22/16 mm mesh). A total of 7.857 specimens were captured, belonging to three species of Chondrichthyes and 95 species of Actinopterygii (77 genera and 40 families). The occurrence of Ampharius phrygiatus represents a southern range extension for this species, which was previously known only from the narrow coastal stretch between Guyana and Maranhão State (Brazil). The record of Synodus poeyi represents the first record of this species in Brazil and in the South Atlantic, as it was previously recorded only in the Caribbean. The general structure of the demersal fish assemblage is described and commented upon.

Apresentamos aqui um inventário de peixes demersais da plataforma continental interna em frente a Ilhéus, Bahia, Brasil. Três locais foram amostrados mensalmente, entre março de 2003 e fevereiro de 2005, com arrastos de fundo padronizados (30 minutos, 16 m de profundidade, malha de 22/16 mm). Foram capturados 7,793 indivíduos pertencentes a três espécies de Chondrichthyes e 95 espécies de Actinopterygii (77 gêneros e 40 famílias). A ocorrência de Ampharius phrygiatus representa uma extensão do limite sul conhecido para essa espécie, que era conhecida de um trecho costeiro relativamente restrito, entre a Guiana e o Maranhão (Brasil). O registro de Synodus poeyi representa o primeiro registro dessa espécie no Brasil e no Atlântico Sul, uma vez que ela havia sido previamente registrada apenas no Caribe. A estrutura geral da assembléia de peixes demersais é descrita e comentada.

Desenvolvimento ovariano de Plagioscion squamosissimus (Heckel, 1840) (Actinopterygii, Perciformes), no reservatório de Pedra, Rio de Contas, Bahia / Ovarian development of Plagioscion squamosissimus (Heckel, 1840) (Actinopterygii, Perciformes), from the Pedra reservoir, Contas river, Bahia

O presente estudo tem por objetivo caracterizar a organização dos ovócitos e os estádios maturacionais do ovário da pescada Plagioscion squamosissimus. As coletas foram realizadas bimestralmente no reservatório de Pedra, rio de Contas (BA), entre novembro de 2004 e setembro de 2006. As análises microscópicas foram realizadas através de cortes histológicos, corados com hematoxilina - eosina - floxina e mistura tricrômica de Gomori. Através da análise macro e microscópica, foram identificados cinco estádios maturacionais. A coloração das gônadas variou de acordo com o desenvolvimento gonadal. Para o desenvolvimento ovocitário, foram definidas seis fases: ovogônia e perinucleolar; vitelogênica e lipídica inicial; vitelogênica e lipídica intermediária; vitelogênica e lipídica avançada e pré-ovulação. Foram observadas estruturas semelhantes às de peixes marinhos, como fusão de gotículas de óleo nas fases finais de maturação e hidratação pré-ovulatória. Estas características podem ser explicadas pela origem marinha da família Sciaenidae, indicando a necessidade de estudos mais detalhados para compreender o aparecimento, desenvolvimento e função dessas estruturas ao longo do desenvolvimento ovocitário.

This study aimed to characterize oocyte organization and maturation stages of Plagioscion squamosissimus ovary. Samples were collected bimonthly in Pedra reservoir, Contas River (BA), between November 2004 and September 2006. Microscopic analyses were made on histological cuts stained with hematoxylin - eosin - phloxine and Gomori trichromic mixture. Five maturation stages were identified through macro and microscopic analysis. Gonad coloration varied according to maturation stages. Six phases of oocyte development were identified: oogonia and perinucleolar, vitellogenic and early lipidic, vitellogenic and intermediate lipidic, vitellogenic and advanced lipidic, and pre-ovulation. Cell structures were similar to those found among marine species, such as oil droplets fusion at later developmental stages and pre-ovulatory hydration. Such features may be explained by the marine origin of Sciaenidae, thus suggesting the need of more detailed studies for understanding the origin, development and function of these structures along oocyte developmental stages.

Low levels of genetic diversity depicted from mitochondrial DNA sequences in a heavily exploited marine fish (Cynoscion acoupa, Sciaenidae) from the Northern coast of Brazil

The acoupa weakfish (Cynoscion acoupa - Sciaenidae) is a marine species of croaker with estuarine-dependent behavior, found in the western Atlantic from Panama to Argentina. It is one of the most exploited food fish on the northern coast of Brazil. In this study, DNA sequences were determined from the entire control region (D-loop) of the mitochondrial genome of 297 individuals collected during seven different months between December 2003 and August 2005 on the northern coast of Brazil (Amapá and Pará). Genetic variability expressed by haplotype (h = 0,892) and nucleotide (pi = 0,003) diversities were low compared to other heavily exploited marine fish species from the western Atlantic and eastern Asia. AMOVA depicted a lack of genetic structuring among the samples from different years, indicating the presence of a single stock of C. acoupa within the sample area. The possible reasons for the low levels of genetic diversity are discussed. These results demonstrate a need for the monitoring of C. acoupa harvesting and the preservation of the estuaries within its geographic range, considering that this large fish depends on estuarine ecosystems during part of its life cycle.

Cytogenetic studies in Brazilian marine Sciaenidae and Sparidae fishes (Perciformes)

Fishes from the families Sciaenidae and Sparidae, the former comprising coastal species associated with shallow waters on the continental shelf and the latter composed of typically marine species, are of significant economic value. Karyotypic data are available for about 20% of the total number of species in these groups. In the present study, cytogenetic analyses were carried out in three Sciaenidae species, Menticirrhus americanus, Ophioscion punctatissimus and Pareques acuminatus, as well as in the sparid fish, Archosargus probatocephalus, using conventional staining (Giemsa) and Ag-nucleolar organizer regions (NORs) and C-banding techniques. The diploid values (2n) and number of chromosome arms were equal to 48 in all species analyzed. NORs were located at pericentromeric positions, equivalent to large heterochromatic blocks, in M. americanus (1st pair), O. punctatissimus (10th pair), P. acuminatus (2nd pair), and A. probatocephalus (3rd pair). Heterochromatin was detected at the centromeric position in most chromosome pairs, being more conspicuous among Scianidae members. The remarkable karyotypic conservativeness detected in these species is similar to that observed in other perciform groups previously studied, regarding both the number of acrocentric chromosomes and NOR location. However, unusual events of heterochromatinization seem to have taken place along the karyotypic evolution of members of the family Sciaenidae. For the family Sparidae, distinct cytotypes between samples of Northeast Brazil and those previously analyzed on the southeastern coast were identified, suggesting that putative biogeographic barriers could be present throughout both regions on South Atlantic coast.

5S rDNA characterization in twelve Sciaenidae fish species (Teleostei, Perciformes): depicting gene diversity and molecular markers

In order to extend the genetic data on the Sciaenidae fish family, the present study had the purpose to characterize PCR-generated 5S rDNA repeats of twelve species of this group through PAGE (Polyacrylamide Gel Electrophoresis) analysis. The results showed the occurrence of at least two different 5S rDNA size classes in all the species. Moreover, 5S rDNA repeats of one of the studied species - Isopisthus parvipinnis - were cloned and subjected to nucleotide sequencing and Southern blot membrane hybridization analyses, which permitted to confirm the existence of two major 5S rDNA classes. Phylogenetic analysis based on the nucleotide sequences of different 5S rDNA repeats of I. parvipinnis lead to their separation into two major clusters. These results may reflect the high dynamism that rules the evolution rate of 5S rDNA repeats. The obtained data suggest that 5S rDNA can be useful in genetic analyses to identify species-specific markers and determine relationships among species of the Sciaenidae group.

Description of a new weakfish, Cynoscion nortoni, from Ecuador with a note on the distribution of Umbrina bussingi (Perciformes: Sciaenidae)

A new sciaenid was found at a fish market on the Ecuadorian coast. Cynoscion nortoni, described from 11 specimens, is characterised by a relatively large eye, a long head and pectoral fin, a high dorsal fin-ray count and a dark, steel grey colour on its dorsum. The specimens were captured over the continental shelf with a long line at depths between 100 and 200 meters. Another deep water species, Umbrina bussingi, is recorded for the first time from southern Colombia.

Descrição de duas novas espécies de Sciaenidae (Perciformes) de água doce da Bacia Amazônica

Two new species of freshwater Sciaenidae genera Pachyurus and Plagioscion are described from Amazon River basin. Pachyurus junki sp. n. differs from its congeners by the following characters combination: posterior tip of pelvic fin distant from the anus, interorbital width less than 6.0 times in the head length, second anal fin spine more than 2.1 times in the head length, 29 to 33 soft rays in the dorsal fin, 11 to 16 rows of scales above to lateral line, 11 to 16 rows of scales below, and 58 to 68 perfored scales in the lateral line. Plagioscion montei sp. n. differs from its congeners by having: anus distant from the anal fin, the distance anus-anal fin from 2.4 to 5.0 times in the head length; pectoral fin relatively long, when adpressed its posterior tip reaches or surpasses the vertical line that crosses the anus; interorbital width relatively large, from 3.5 to 4.9 times in the head length, and second anal fin spine strong and short, from 2.5 to 4.4 times in the head length.

São descritas duas novas espécies de Sciaenidae da região Amazônica, pertencentes aos gêneros Pachyurus e Plagioscion. Pachyurus junki sp. n. difere das demais espécies congenéricas descritas por apresentar a seguinte combinação de caracteres: extremidade posterior da nadadeira pélvica distante do ânus; largura interorbital contida menos do que 6,0 vezes no comprimento da cabeça; segundo espinho da nadadeira anal contido mais do que 2,1 vezes no comprimento da cabeça; 29 a 33 raios na nadadeira dorsal; 11 a 16 séries de escamas acima da linha lateral; 11 a 16 séries de escamas abaixo da linha lateral e 58 a 68 escamas perfuradas na linha lateral. Plagioscion montei sp. n. difere das demais espécies do gênero por apresentar: ânus distante da nadadeira anal, estando a distância ânus-anal contida de 2,4 a 3,5 vezes no comprimento da cabeça; nadadeira peitoral relativamente longa, quando adpressa sua extremidade posterior chega próximo ou ultrapassa a linha vertical que passa pela origem do ânus; largura interorbital relativamente ampla, contida entre 3,5 e 5,0 vezes no comprimento da cabeça e segundo espinho da nadadeira anal forte e curto, contido de 2,5 a 4,4 vezes no comprimento da cabeça.