The food spectrum of the cardinal - tetra (Paracheirodon axelrodi, Characidae) in its natural habitat

The cardinal tetra (Paracheirodon axelrodi) is the most intensively commercialized ornamental fish from the Rio Negro Basin (Amazonas State, Brasil). Analysis of the stomach and gut contents of fish caught in their natural habitats show conclusively that the cardinal is essentially a predator, feeding on the mesofauna that adheres to submerged litter, roots and waterplants. Microcrustacea and chironomid larvae (Diptera) were the most frequently ingested prey, while algae intake was relatively infrequent. It is argued that the relatively small size of the cardinals captured in their natural habitat is due to the annual migrations imposed by the inundation cycles, rather than to resource limitation, because it is known from earlier investigations of similar habitats, that these plant substrates are densely colonized by the aquatic mesofauna. Cardinals raised in captivity are larger and have higher rates of growth.

Parasite-host relationship between the tambaqui (Colossoma macropomum Cuvier 1818) and ectoparasites, collected from fish farms in the city of Rolim de Moura, State of Rondônia, Western Amazon, Brazil

In this study we investigated the relationship between tambaqui fish (Colossoma macropomumi Cuvier 1818) and parasites in two fish farms (L204S and L180N) in the state of Rondônia, Brazil, during a 1-year period. The objective of the study was to describe the relationships between parasites, hosts and the environment. From the 80 fish specimens collected, 100% were parasitized by at least one parasite species. Seven ectoparasites species were recorded, six of the class Monogenea: Anacanthorus spathulatusi, Mymarothecium spp. (Mymarothecium sp. 1, Mymarothecium sp. 2 and M. viatorum), Notozothecium sp. and Linguadactyloides brinkimanni, classified as dominants, and the copepod Perulernaea gamitanae, classified as subordinate. Despite their high prevalence, the parasites were not abundant. A. spathulatus presented positive and significant correlations between the abundance of parasitism and the standard length of the hosts in the two fish farms; Mymarothecium spp. showed significant correlations, negative in L180N, and positive in L204S; significant positive correlations were observed for Notozothecium sp. in L204S, and for L.brinkimanni in L180N. Young monogeneans were found; these parasites presented a negative correlation in L180N and a significant negative correlation in L204S. The results of the correlation between the relative condition factor (Kn) and the abundance of parasites were not significant for the recorded parasite species. Regarding the hepatosomatic relation (HSR) of fish and the abundance of parasites, Anacanthorus spathulatusi showed a significant negative correlation with the HSR in L180N, and a positive correlation in L204S. Mymarothecium spp. and Notozothecium sp. presented significant positive correlations in L204S. Considering the correlation of the fish splenosomatic relation (SSR) and the abundance of parasites, L. brinkimanni presented significant correlations, positive in L180N and negative in L204S. Despite 100% prevalence, the high water quality contributes to infracommunities with low parasite abundance and good levels of Kn, HSR and SSR, allowing good tambaqui development.

Use of the flooded forest by fish assemblages in lakes of the National Park of Anavilhanas (Amazonas, Brazil)

We evaluated diversity and distribution of fish species in two habitats: flooded forest and open water of lakes of Rio Negro. Each of four lakes within the Anavilhanas Archipelago was sampled three times from 2009-2010. Species diversity generally was higher in flooded forests and at night, according to correspondence analysis. Predators were most active at night, but showed no preference between the flooded forest and open water habitats. Omnivores, filter feeders, and detritivores were most active during the day.

A new page on the road book of inorganic mercury in fish body - tissue distribution and elimination following waterborne exposure and post-exposure periods

prova tipográfica / uncorrected proof

Optimization of peptide nucleic acid fluorescence in situ hybridization (PNA-FISH) for the detection of bacteria: the effect of pH, dextran sulfate and probe concentration

Fluorescence in situ hybridization (FISH) is a molecular technique widely used for the detection and characterization of microbial populations. FISH is affected by a wide variety of abiotic and biotic variables and the way they interact with each other. This is translated into a wide variability of FISH procedures found in the literature. The aim of this work is to systematically study the effects of pH, dextran sulfate and probe concentration in the FISH protocol, using a general peptide nucleic acid (PNA) probe for the Eubacteria domain. For this, response surface methodology was used to optimize these 3 PNA-FISH parameters for Gram-negative (Escherichia coli and Pseudomonas fluorescens) and Gram-positive species (Listeria innocua, Staphylococcus epidermidis and Bacillus cereus). The obtained results show that a probe concentration higher than 300 nM is favorable for both groups. Interestingly, a clear distinction between the two groups regarding the optimal pH and dextran sulfate concentration was found: a high pH (approx. 10), combined with lower dextran sulfate concentration (approx. 2% [w/v]) for Gram-negative species and near-neutral pH (approx. 8), together with higher dextran sulfate concentrations (approx. 10% [w/v]) for Gram-positive species. This behavior seems to result from an interplay between pH and dextran sulfate and their ability to influence probe concentration and diffusion towards the rRNA target. This study shows that, for an optimum hybridization protocol, dextran sulfate and pH should be adjusted according to the target bacteria.

Diet of the ichthyofauna associated with marginal vegetation of a mangrove forest in southeastern Brazil

The objective of this study was to analyze the diet of fish species that use the mangrove vegetation for shelter and feeding in a river southeastern Brazil. The fieldwork, including collecting and underwater observations, was carried out in the dry (July and August 2004) and in the rainy season (February and March 2005) in order to assess the existence of seasonal variation in the diets. Seven kinds of food items were consumed, two of plant origin and five of animal origin. Crustaceans predominated in the diet of most species, either in the form of unidentified fragments or discriminated in eight groups. The predominance of species using mainly a single food source (crustaceans, principally Ostracoda and Tanaidacea) and the existence of seasonal variation in the diets of some species became very evident in the analysis food niche breadth, with a predominance of dietary specialists. In the Rio da Fazenda mangrove, the submersed marginal vegetation was used by the ichthyofauna as a locale for foraging, and principally as cover by bottom-feeding species. These species may be using the vegetation for protection from aerial and aquatic predators, or even from the pull of the current during the turn of the tide. In the study area, the great diversity of crustaceans constitutes an important food source for most fish species which adjusted their diet according to seasonal changes in food availability and to interactions with other species.

Reproductive characteristics of characid fish species (Teleostei, Characiformes) and their relationship with body size and phylogeny

In this study, I investigated the reproductive biology of fish species from the family Characidae of the order Characiformes. I also investigated the relationship between reproductive biology and body weight and interpreted this relationship in a phylogenetic context. The results of the present study contribute to the understanding of the evolution of the reproductive strategies present in the species of this family. Most larger characid species and other characiforms exhibit a reproductive pattern that is generally characterized by a short seasonal reproductive period that lasts one to three months, between September and April. This is accompanied by total spawning, an extremely high fecundity, and, in many species, a reproductive migration. Many species with lower fecundity exhibit some form of parental care. Although reduction in body size may represent an adaptive advantage, it may also require evolutionary responses to new biological problems that arise. In terms of reproduction, smaller species have a tendency to reduce the number of oocytes that they produce. Many small characids have a reproductive pattern similar to that of larger characiforms. On the other hand they may also exhibit a range of modifications that possibly relate to the decrease in body size and the consequent reduction in fecundity. Examples of changes in the general reproductive pattern include the following: reduction in the size of mature oocytes; increase in fecundity; production of several batches of oocytes; an extended reproductive period or even continuous reproduction that allows individuals to reproduce more than once a year; high growth rates; rapid recruitment of juveniles; presence of more than one reproductive cohort that increases the sexually active population; and multiple independent development of insemination as a reproductive strategy. These changes are possibly associated with adaptive pressures that are related to the reduction in body size. In addition, such reproductive characteristics or novelties may reflect the phylogenetic history of a given species.

Comparative dietary analysis of Eurycheilichthys pantherinus and Pareiorhaphis hystrix: two Loricariidae species (Ostariophysi, Siluriformes) from Campos Sulinos biome, southern Brazil

This work was carried out in Marco river, São José dos Ausentes municipality, state of Rio Grande do Sul, southern Brazil. This region is located within the Campos Sulinos biome, an area of great biological importance due to its high diversity and endemism of fish. The feeding habits and food overlap between Eurycheilichthys pantherinus (Reis & Schaefer, 1992) (n=108) and Pareiorhaphis hystrix Pereira & Reis, 2002 (n=60) are described. Monthly samples were obtained between September 2000 and July 2001 with dipnets using the kick sampling technique. Stomach contents were analyzed based on frequency of occurrence, volumetric frequency and index of alimentary importance. The level of dietary specialization and food overlap were determined by the Levins measure and the Morisita index, respectively. Eurycheilichthys pantherinus fed mainly on immature aquatic insects, such as Dipterans and Ephemeropterans, and was classified as insectivore. Pareiorhaphis hystrix fed mainly on detritus associated with small amounts of aquatic insects, and was classified as detritivore. Species are clearly segregated by the use of food resources in Marco River. Their diets did not overlap and the differences observed in their feeding habits probably contribute for their coexistence.

The diet of the South American sea lion (Otaria flavescens) at Río Negro, Patagonia, Argentina, during the winter-spring period

The South American sea lion, Otaria flavescens (Shaw, 1800) population is steadily expanding along the Patagonian coast of Argentina in the last decades. However, little is known about the feeding ecology of the species in the area. The aim of this study was to analyze the food habits of O. flavescens from 91 scats collected at Río Negro province, during the winter and spring of 2005. Fish occurred in 96% of scats containing prey remains, followed by cephalopods (26%). Raneya brasiliensis (Kaup, 1856) was the most frequent and abundant species occurring in 58.6% of samples and constituting almost 50% of fish predated. Second in importance were Porichthys porosissimus (Cuvier, 1829) and Cynoscion guatucupa (Cuvier, 1830) in terms of occurrence (%FO 20.7) and numbers (29.6%) respectively. The squid Loligo gahi (d'Orbigny, 1835) was the most frequent cephalopod prey (42.1%), whereas Octopus tehuelchus (d'Orbigny, 1834) was the most abundant (77%). The higher amount and diversity of prey found in the spring in comparison with the winter season might be related to a higher feeding activity of seals or to a seasonal increase in food availability in the area.

Diel vertical migration of predators (planktivorous fish larvae) and prey (zooplankton) in a tropical lagoon

ABSTRACT Based on the hypothesis that diel vertical migration (DVM) is a mechanism of predator avoidance, the objective of the present study was to test for the occurrence of DVM in planktivorous fish larvae of Hypophthalmus edentatus (Spix, 1829) (Siluriformes, Pimelodidae) and Plagioscion squamosissimus (Heckel, 1840) (Perciformes, Sciaenidae), and zooplankton (rotifers, cladocerans and copepods) in an isolated tropical lagoon in the floodplain of the Upper Paraná River, Brazil (region of Parque Nacional de Ilha Grande). We investigated spatial overlap between predators (planktivorous fish larvae) and prey (zooplankton), and tested which physical and chemical variables of the water are related to the DVM of the studied communities. We performed nocturnal (8:00 pm and 4:00 am) and diurnal sampling (8:00 am and 4:00 pm) in the limnetic region of the lagoon for six consecutive months, from October 2010 to March 2011, which comprises the reproductive period of the fish species analyzed. During the day the larvae tried to remain aggregated in the bottom of the lagoon, whereas at night they tried to disperse in the water column. Especially for cladocerans, the diel vertical migration is an important behavior to avoid predation larvae of H. edentatus and P. squamosissimus once decreased spatial overlap between secured and its potential predators, which corroborates the hypothesis that DVM is a mechanism of predator avoidance. Although significant correlations were observed between the abiotic factors and WMD of microcrustaceans at certain times of day, the effect of predation of fish larvae on zooplankton showed more important in this environment, because the small depth and isolation not allow great variation of abiotic factors seasonally and between strata the lagoon.

Opisthorchiasis in infant remains from the medieval Zeleniy Yar burial ground of XII-XIII centuries AD

We present a paleoparasitological analysis of the medieval Zeleniy Yar burial ground of the XII-XII centuries AD located in the northern part of Western Siberia. Parasite eggs, identified as eggs of Opisthorchis felineus, were found in the samples from the pelvic area of a one year old infant buried at the site. Presence of these eggs in the soil samples from the infant’s abdomen suggests that he/she was infected with opisthorchiasis and imply consumption of undercooked fish. Ethnographic records collected among the population of the northern part of Western Siberia reveal numerous cases of feeding raw fish to their children. Zeleniy Yar case of opisthorchiasis suggests that this dietary custom has persisted from at least medieval times.

Differences in diet between the two largest breeding colonies of Audouin's gulls: the effects of fishery activities

We analysed and compared the diet of Audouin´s gulls Larus audouinii between their two largest breeding sites in the world: the Ebro Delta and the Chafarinas Islands (western Mediterranean). These two localities showed marked differences in the features of the commercial fishing fleet: in the Ebro Delta area a large fishing fleet produced large amounts of discards, while in the Chafarinas the fleet discarded smaller amounts of fish and marine invertebrates, due to the smaller number of vessels. It is also likely that the percentage of discards from total catches is also lower around the Chafarinas than at the Ebro Delta. We distinguished two types of fishing to compare diet compositions: diurnal (only trawling activity) and diurnal and nocturnal (trawling and purse-seine activity, respectively). We also differentiated regurgitates from young nestlings (up to 20 days old) and from older nestlings or adult birds. At the two localities, fish was the main food of Audouin´s gulls, with epipelagic prey (mainly clupeoids) being more important when both diurnal and nocturnal fisheries were operating. This confirms that epipelagic prey either caught actively by the gulls or linked to fisheries was particularly important in the feeding habits of Audouin´s gulls. Nevertheless, differences between the two colonies appear mainly when only trawlers operated: while at the Ebro Delta gulls showed higher consumption of benthic-mesopelagic prey (probably linked to a higher trawler discard availability), gulls from the Chafarinas Islands consumed higher biomass of epipelagic prey probably caught actively at night. When both fleets operated around the two colonies, the average biomass of prey in a regurgitate of younger chicks was significantly higher at the Ebro Delta than at Chafarinas, and the opposite trend was recorded for older nestlings and adults. Niche width was broader in Chafarinas than in the Ebro Delta for both age classes and for any fishing fleet schedule, suggesting again that the exploitation of discards was higher at the Ebro Delta than at the Chafarinas, where gulls showed a more varied diet. Despite the fact that availability of discards was probably higher at the Ebro Delta than at Chafarinas, the per capita availability was not so different at both localities due to the increasing seabird community population at the Ebro Delta, which ca. doubled that at Chafarinas in the last decade.

Differences in diet between the two largest breeding colonies of Audouin's gulls: the effects of fishery activities

We analysed and compared the diet of Audouin´s gulls Larus audouinii between their two largest breeding sites in the world: the Ebro Delta and the Chafarinas Islands (western Mediterranean). These two localities showed marked differences in the features of the commercial fishing fleet: in the Ebro Delta area a large fishing fleet produced large amounts of discards, while in the Chafarinas the fleet discarded smaller amounts of fish and marine invertebrates, due to the smaller number of vessels. It is also likely that the percentage of discards from total catches is also lower around the Chafarinas than at the Ebro Delta. We distinguished two types of fishing to compare diet compositions: diurnal (only trawling activity) and diurnal and nocturnal (trawling and purse-seine activity, respectively). We also differentiated regurgitates from young nestlings (up to 20 days old) and from older nestlings or adult birds. At the two localities, fish was the main food of Audouin´s gulls, with epipelagic prey (mainly clupeoids) being more important when both diurnal and nocturnal fisheries were operating. This confirms that epipelagic prey either caught actively by the gulls or linked to fisheries was particularly important in the feeding habits of Audouin´s gulls. Nevertheless, differences between the two colonies appear mainly when only trawlers operated: while at the Ebro Delta gulls showed higher consumption of benthic-mesopelagic prey (probably linked to a higher trawler discard availability), gulls from the Chafarinas Islands consumed higher biomass of epipelagic prey probably caught actively at night. When both fleets operated around the two colonies, the average biomass of prey in a regurgitate of younger chicks was significantly higher at the Ebro Delta than at Chafarinas, and the opposite trend was recorded for older nestlings and adults. Niche width was broader in Chafarinas than in the Ebro Delta for both age classes and for any fishing fleet schedule, suggesting again that the exploitation of discards was higher at the Ebro Delta than at the Chafarinas, where gulls showed a more varied diet. Despite the fact that availability of discards was probably higher at the Ebro Delta than at Chafarinas, the per capita availability was not so different at both localities due to the increasing seabird community population at the Ebro Delta, which ca. doubled that at Chafarinas in the last decade.

Effects of total fishing prohibition on the rocky fish assemblages of Medes Islands marine reserve (NW Mediterranean)

Visual scuba diving censuses were used to assess the effects of fishing prohibition on abundance and size structure of littoral fish populations by comparing the same benthic communities inside and outside the protected area of Medes Islands (NE Catalonia, Spain). The total number of species found was 43 in the reserve and 44 outside, but the mean value of species richness per sampling station was significantly higher in the protected area. However, diversity, heavily affected by the presence or absence of large schools of pelagic species, showed no significant differences between sites. The prohibition of fishing for 6 years is the first factor affecting the qualitative and quantitative structure of fish populations ('reserve effect'), and depth is the second factor. Thus, except in the cases of Serranus cabrilla and Mullus surmuletus, all other vulnerable species are highly sensitive to the protection measures. The size structure of all vulnerable species was found to be absolutely different at the reserve sites than in the unprotected zones, and the modal size classes of size frequency distributions were always higher in the reserve than outside. The reserve effect was significantly responsible of the differences observed in this change on size structure. Some highly vulnerable species, such as Epinephelus guaza and Sciaena umbra, have only been found in the protected area. Others, such as Sparus aurata, Diplodus cervinus and Dicentrarchus labrax, were much more frequent inside the reserve.

2015 Iowa Fish Tissue Monitoring Program Summary of Analyses

To supplement other environmental monitoring programs and to protect the health of people consuming fish from waters within this state, the state of Iowa conducts fish tissue monitoring. Since 1980, the Iowa Department of Natural Resources (IDNR), the United States Environmental Protection Agency Region VII (U.S. EPA), and the State Hygienic Laboratory (SHL) have cooperatively conducted annual statewide collections and analyses of fish for toxic contaminants. From 1983 to 2014, this monitoring effort was known as the Regional Ambient Fish Tissue Monitoring Program (RAFT). Beginning in 2015, the only statewide fish contaminant-monitoring program in Iowa was changed to the Iowa Fish Tissue Monitoring Program (IFTMP). The IFTMP is administered by IDNR and the tissue analyses are completed at the SHL. Historically, the data generated from the IFTMP have enabled IDNR to document temporal changes in contaminant levels and to identify Iowa lakes and rivers where high levels of contaminants in fish potentially threaten the health of fish-consuming Iowans (see IDNR 2006). The IFTMP incorporates five different types of monitoring sites: 1) status, 2) follow-up, 3) trend, 4) turtle, and 5) random.