Trophic relationships between macroinvertebrates and fish in a pampean lowland stream (Argentina)

The diet and trophic relationships between the macroinvertebrates Phyllogomphoides joaquini Rodrigues Capítulo, 1992 and Coenagrionidae (Odonata), Chironomidae (Diptera), Diplodon delodontus (Lamarck, 1919) (Bivalvia: Hyriidae), and Pomacea canaliculata (Lamarck, 1822) (Gastropoda: Ampulariidae) and the fishes Pimelodella laticeps Eigenmann, 1917 (Heptapteridae) and Bryconamericus iheringii (Boulenger, 1887) (Characidae) in a temperate lowland lotic system in Argentina were assessed on the basis of gut contents and stable-isotope analyses. The feeding strategies were analyzed by the AMUNDSEN method. Relative food items contribution for the taxa studied indicated a generalist-type trophic strategy. In macroinvertebrates, in general, the values of stable isotope confirmed the result of the analysis of gut contents. With the fish, stable-isotope analysis demonstrated that both species are predators, although B. iheringii exhibited a more omnivorous behaviour. These feeding studies allowed us to determine the trophic relationships among taxa studied. Detritus and diatoms were a principal source of food for all the macroinvertebrates studied. In La Choza stream the particulate organic matter is a major no limited food resource, has a significant influence upon the community.

Influência do nível hidrológico sobre a dieta de Leporinus reinhardtii (Characiformes, Anostomidae) em um reservatório do semiárido brasileiro

A Região Neotropical possui um elevado número de espécies de peixes de água doce, cujas adaptações para explorar diferentes tipos de alimento é particularmente evidente em reservatórios, refletindo numa considerável plasticidade alimentar. Characiformes é a mais diversificada ordem de peixes da região, tendo Anostomidae como uma das famílias mais especiosas, com destaque para Leporinus, com cerca de 80 espécies válidas. Embora suas espécies sejam consideradas primordialmente onívoras, algumas apresentam dieta herbívora, e a plasticidade alimentar do gênero é uma característica comum em ambientes sujeitos a variação sazonal de nível da água. No presente trabalho, são analisadas a composição da dieta de Leporinus reinhardtii Lütken, 1875 no reservatório de Sobradinho e a influência da variação sazonal de seu nível sobre a mesma ao longo de três ciclos anuais (2006-2009). Dentre os 876 indivíduos analisados, 302 foram coletados no período de seca e 574 no de cheia. A dieta foi composta por 47 itens, agrupados em nove categorias: Moluscos, Microcrustáceos, Insetos, Insetos (partes), Chironomidae, Vegetais, Sementes, Sedimento e Outros. Chironomidae representou em média 60% do peso total das categorias alimentares, seguido de Sementes com 25% e as demais categorias com menos de 10%. No período de cheia, nos trechos lêntico e de transição, predominaram Sementes na dieta, tendo Chironomidae sido mais representativa no trecho lótico, e as demais categorias não ultrapassando 20% de participação nos três trechos neste período. No período de seca, houve diferença nos itens predominantes, com predominância de Insetos no trecho lêntico, principalmente Coleoptera, e de Vegetais no lótico, com maior participação de macrófitas aquáticas, algas filamentosas, clorofíceas e da diatomácea Oscillatoria. Já no trecho de transição, Microcrustáceos dominaram na dieta, diferindo dos demais trechos. A dieta de L. reinhardtii se caracterizou por baixos valores de frequência de ocorrência de todas as categorias alimentares (predominantemente inferiores a 50%) e elevada abundância relativa (>80%) de diferentes categorias. A amplitude de nicho foi restrita nos diferentes trechos nos dois períodos, sendo ligeiramente mais elevada na cheia, devido à maior diversidade de itens, em particular no trecho lêntico. Leporinus reinhardtii possui hábito onívoro com comportamento especialista no reservatório de Sobradinho, cujas categorias predominantes da dieta dependem do regime hidrológico do reservatório e das características ambientais de cada trecho, refletindo numa amplitude restrita de nicho trófico para a espécie.

Estudo da dieta natural da ictiofauna de um reservatório centenário, São Paulo, Brasil

Este estudo teve como objetivo caracterizar e comparar a alimentação de 13 espécies de peixes em três zonas (zona de influência fluvial, zona de transição e zona lacustre) do reservatório de Itupararanga. Foram analisados 436 estômagos, sendo encontrados 17 recursos alimentares, todos de origem autóctone. As dietas predominantes das espécies foram: peixe, inseto, material vegetal e detritos na zona de influência fluvial, peixe, sedimento e material vegetal na zona de transição e inseto, escama e peixe na zona lacustre. Através do Índice Alimentar, as espécies foram categorizadas nas guildas: piscívora, insetívora, detritívora e carcinófaga. O Cluster indicou separação da guilda insetívora em espécies generalistas (insetos diversos) e especialista (Chironomidae) o que aumenta para cinco guildas. Na zona fluvial foram verificadas quatro guildas; na zona de transição três guildas e na zona lacustre duas guildas. Observou-se ainda uma dominância de espécies piscívoras que pode estar relacionada à idade do reservatório. Este estudo ampliou o conhecimento dos hábitos alimentares dos peixes em reservatórios antigos e suas diferenças, comparando as zonas existentes.

Colonização de macroinvertebrados bentônicos em detritos foliares em um riacho de primeira ordem na Floresta Atlântica do nordeste brasileiro

O objetivo do estudo foi avaliar a colonização de macroinvertebrados bentônicos em detritos foliares de Inga ingoides (Leguminosae) em experimentos de campo em um riacho de primeira ordem da Mata Atlântica do Estado de Pernambuco no nordeste do Brasil. Um total de 270 bolsas de folhiço, distribuídas em três trechos do riacho com características similares em relação à morfologia e parâmetros físicos e químicos da água foram submersas, entre fevereiro a julho de 2013 e retiradas após 7, 30, 60, 90 e 120 dias. Dois tratamentos foram utilizados: colonização e exclusão da macrofauna. O percentual de biomassa remanescente final (%R) foi maior para bolsas de colonização do que para as de exclusão, evidenciando a efetiva participação dos macroinvertebrados no processo de decomposição. Os fragmentadores apresentaram menor participação no processo de decomposição foliar de I. ingoides, sendo Tripletides (Trichoptera: Leptoceridae), Polypedillum e Stenochironomus (Diptera, Chironomidae) os táxons predominantes na macrofauna. Filtrador foi o grupo trófico funcional predominante (45,6%), seguido por predador (31,2%), coletor (11,8%), raspador (6,7%) e fragmentador (4,8%).

Assessing the performance of macroinvertebrate metrics in the Challhuaco-Ñireco System (Northern Patagonia, Argentina)

ABSTRACT Seven sites were examined in the Challhuaco-Ñireco system, located in the reserve of the Nahuel Huapi National Park, however part of the catchment is urbanized, being San Carlos de Bariloche (150,000 inhabitants) placed in the lower part of the basin. Physico-chemical variables were measured and benthic macroinvertebrates were collected during three consecutive years at seven sites from the headwater to the river outlet. Sites near the source of the river were characterised by Plecoptera, Ephemeroptera, Trichoptera and Diptera, whereas sites close to the river mouth were dominated by Diptera, Oligochaeta and Mollusca. Regarding functional feeding groups, collector-gatherers were dominant at all sites and this pattern was consistent among years. Ordination Analysis (RDA) revealed that species assemblages distribution responded to the climatic and topographic gradient (temperature and elevation), but also were associated with variables related to human impact (conductivity, nitrate and phosphate contents). Species assemblages at headwaters were mostly represented by sensitive insects, whereas tolerant taxa such as Tubificidae, Lumbriculidae, Chironomidae and crustacean Aegla sp. were dominant at urbanised sites. Regarding macroinvertebrate metrics employed, total richness, EPT taxa, Shannon diversity index and Biotic Monitoring Patagonian Stream index resulted fairly consistent and evidenced different levels of disturbances at the stream, meaning that this measures are suitable for evaluation of the status of Patagonian mountain streams.

Plancto e hidrobiologia sanitária de tanques tropicais com dáfnias e rotíferos

The engineers of the modern University City are constructing a graceful bridge, named PONTE OSWALDO CRUZ, that crosses a portion of the Guanabara Bay (Fig. 1). The work at west pillar stopped for 3 years (The concret structure in Est. 1). As it will be seen from n.º 1 — 5 of the fig. 1, Est. I, the base of the structure will have five underground boxes of reinforcement, but, to-day they are just like as five uncovered water ponds, until at present: May 1963. (Est. I — fig. 3, n.º 3 — pond n.º 3; A. — old level of the water; B.— actual level of the water; c.— green water; E.— mass of bloom of blue algae Microcystis aeruginosa). Soon after SW portion, as 5 cells in series, of the pillar abutments, and also the NE portion nearly opposite in the Tibau Mount will be filled up with earth, a new way will link Rio City and the University City. We see to day Est. I, fig. 1 — the grasses on the half arenous beach of the Tibau Point. These natural Cyperaceae and Gramineae will be desappear because of so a new road, now under construction, when completed will be 33 feet above the mean sea level, as high as the pillar, covering exactly as that place. Although rainfall was the chief source of water for these ponds, the first water (before meterorological precipitations of whatever first rain it might fall) was a common tap water mixed with Portland Cement, which exuded gradually through the pores of the concret during its hardenning process. Some data of its first cement water composition are on the chemical table, and in Tab. n.º 4 and "Resultado n.º 1". The rain — receiving surface of each pond were about 15 by 16 feet, that is, 240 square feet; when they were full of water, their depth was of 2 feet 3", having each pond about 4,000 gallons. Climatic conditions are obviously similar of those of the Rio de Janeiro City: records of temperature, of precipitation and evaporation are seen on the graphics, figs. 2, 3, 4. Our conceptions of 4 phases is merely to satisfy an easy explanation thus the first phase that of exudation of concrete. We consider the 2nd. phase formation of bacterian and cyanophycean thin pellicel. 3rd. phase - dilution by rains, and fertilisation by birds; the 4th phase - plankton flora and fauna established. The biological material arrived with the air, the rains, and also with contaminations by dusts; with big portion of sand, of earth, and leaves of trees resulted of the SW wind actions in the storming days (See - Est. I, fig. 3, G. - the mangrove trees of the Pinheiro Island). Many birds set down and rest upon the pillar structure, its faeces which are good fertilizers fall into the ponds. Some birds were commonly pigeons, black ravens, swallows, sparrows and other sea mews, moor hens, and a few sea birds of comparatively rare occurence. We get only some examples of tropical dust contaminated helioplankton, of which incipient observations were been done sparcely. See the systematic list of the species of plankters. Phytoplankters - Cyanophyta algae as a basic part for food of zooplankters, represented chiefly by rotiferse, water-fleas Moinodaphnia and other Crustacea: Ostracoda Copepoda and Insecta: Chironomidae and Culicidae larvae. The polysaprobic of septic irruptions have not been done only by heating in summer, and, a good reason of that, for example: when the fifth pond was in polysaprobic phase as the same time an alike septic phase do not happened into the 3rd. pond, therefore, both were in the same conditions of temperature, but with unlike contaminations. Among the most important aquatic organisms used as indicatiors of pollution - and microorganisms of real importance in the field of sanitary science, by authorities of renown, for instance: PALMER, PRESCOTT, INGRAM, LIEBMANN, we choose following microalgae: a) The cosmopolite algae Scenedesmus quadricuada, a common indicator in mesosaprobio waters, which lives between pH 7,0 and it is assimilative of NO[3 subscripted] and NH[4 subscripted]. b) Species of the genus Chlamydomonas; it is even possible that all the species of theses genus inhabit strong-mesosaprobic to polysaprobic waters when in massive blooms. c) Several species of Euglenaceae in fast growing number, at the same time of the protozoa Amoebidae, Vorticellidae and simultaneous with deposition of the decaying cells of the blue algae Anacystis cyanea (= Microcystis) when the consumed oxygen by organic matter resulted in 40 mg. L. But, we found, among various Euglenacea the cosmopolite species (Euglena viridis, a well known polysaprobic indicatior of which presence occur in septic zone. d) Analcystis cyanea (= M. aeruginosa) as we observed was in blooms increasing to the order of billions of cells per litter, its maximum in the summer. Temperatures 73ºF to 82ºF but even 90ºF, the pH higher than 8. When these blue algae was joined to the rotifer Brachionus calyflorus the waters gets a milky appearance, but greenished one. In fact, that cosmopolite algae is used as a mesosaprobic indicator. Into the water of the ponds its predominance finished when the septic polysaprobic conditions began. e) Ankistrodesmus falcatus was present in the 5th pond from 26the. April untill the 26th July, and when N.NH[4 subscripted] gets 1.28 mg. L. and when chlorinity stayed from 0.034 to 0.061 mg. L. It never was found at N.NH[4 subscripted] higher than 1 mg. L. The green algae A. falcatus, an indicatior of pollution, lives in moderate mesosaprobic waters. f) As everyone knows, the rotifer eggs may be widely dispersed by wind. The rotifer Asplanchna brightwelli in our observation seemed like a green colored bag, overcharged by green cells and detritus, specially into its spacious stomach, which ends blindly (the intestine, cloaca, being absent). The stock of Asplanchna in the ponds, during the construction of the bridge "PONTE OSWALDO CRUZ" inhabits alkaline waters, pH 8,0 a 8,3, and when we observed we noted its dissolved oxygen from 3.5 to 4 mg. L. In these ponds Asplanchna lived in 0,2 P.PO[4 subscripted]. (Remember the hydobiological observations foreign to braslian waters refer only from 0.06 to 0,010 mg. L. P.PO[4 subscripted]; and they refer resistance to 0.8 N.NH[4 subscripted]). By our data, that rotiger resist commonly to 1.2 until 1.8 mg. L.N.NH[4 subscripted]; here in our ponds and, when NO[2 subscripted] appears Asplanchna desappears. It may be that Asplanchna were devoured by nitrite resistant animals of by Culicidae or other mosquitoes devoured by Due to these facts the number and the distribution of Asplanchna varies considerabley; see - plates of plankton successions. g) Brachionus one of the commonest members of class Rotatoria was frquently found in abundance into the ponds, and we notice an important biological change produce by the rotifer Brachonus colyciflorus: the occurence of its Brachionus clayciflorus forms pallas, is rare in Brazil, as we know about this. h) When we found the water flea MOinodaphnia we do not record simultanous presence of the blue algae Agmenellun (= Merismopedia).

Occurence of larval Culicidae (Diptera) in water retained in Aquascypha hydrophora (Fungus: Stereaceae) in Central Amazônia, Brazil

The community structure of insects, especially mosquito larvae, in water held in the fungus Aquascypha hydrophora (Berk.) Reid (Stereaceae) is reported. The study was done in the Adolpho Ducke Forest Reserve, 26 km east of Manaus, AM, Brazil, from September 1998 through November 1999. The most abundant entomofauna were immature Culicidae (n = 121) 91.7%, followed by adult Dytiscidae (n = 3) 2.3%, immature Chironomidae (n = 5) 3.8% and immature Tipulidae (n = 3) 2.3%. Culicidae associated with A. hydrophora comprised species of the subfamilies Anophelinae and Culicinae.

Evaluation of the impact of Bacillus thuringiensis serovar israelensis and Temephos, used for the control of Simulium (Chirostilbia) pertinax Kollar, 1832 (Diptera, Simuliidae) on the associated entomofauna, Paraty, state of Rio de Janeiro, Brazil

The study was set up to evaluate the impact of two commercial larvicide formulations, Bacillus thuringiensis serovar israelensis base (Bti) at 15 ppm/1 min and temephos at 0.03 ppm of active ingredient, used to control Simulium pertinax populations, on associated non-target entomofauna occupying the same breeding sites. The experiments were carried out on the Pedra Branca and Muricana rivers, on the slopes of Serra do Mar massif, municipality of Paraty, state of Rio de Janeiro, Brazil. Bti was applied to the river Pedra Branca and temephosto theriver Muricana. On both rivers, treatment and control sections were labeled as such, each one with two observation posts: slow moving water and fast water regions respectively. Artificial substrata was used to evaluate the abundance of associated entomofauna. Attached immature stages of arthropods were removed from both of its surfaces fortnightly. Were collected, from the two rivers, 28 477 specimens of the entomofauna associated with S. pertinax. The families Hydropsychidae, Chironomidae, Bactidae, Simuliidae, Blephariceridae and Megapodagrionidae were represented. These was an impact of temephos on the entomofauna associated with S. pertinax only in Simuliidae and Chironomidae, and to Bti only in Simuliidae. However, the reduction in their numbers was not statistically significant.

Trichomycetes (Zygomycota) in the digestive tract of arthropods in Amazonas, Brazil

Eight species of Harpellales and three species of Eccrinales (Zygomycota: Trichomycetes) were found associated with the digestive tract of arthropods from terrestrial and aquatic environments in the central Amazon region of Brazil. New species of Harpellales include: Harpella amazonica, Smittium brasiliense, Genistellospora tropicalis in Simuliidae larvae and Stachylina paucispora in Chironomidae larvae. Axenic cultures of S. brasiliense were obtained. Probable new species of Enterobryus (Eccrinales), Harpella, and Stachylina (Harpellales) are described but not named. Also reported are the previously known species of Eccrinales, Passalomyces compressus and Leidyomyces attenuatus in adult Coleoptera (Passalidae), and Smittium culisetae and Smittium aciculare (Harpellales) in Culicidae and Simuliidae larvae, respectively. Comments on the distribution of some of these fungi and their hosts in the Neotropics are provided.

Effect of Bacillus sphaericus Neide on Anopheles (Diptera: Culicidae) and associated insect fauna in fish ponds in the Amazon

ABSTRACTWe analyzed the effects of Bacillus sphaericus on Anopheles larvae and on the associated insect fauna in fish farming ponds. Five breeding sites in the peri-urban area of the city of Manaus, AM, Brazil, were studied. Seven samples were collected from each breeding site and B. sphaericus was applied and reapplied after 15 days. The samples were made at 24 h before application, 24 h post-application and 5 and 15 days post-application. We determined abundance, larval reduction and larval density for Anopheles, and abundance, richness, Shannon diversity index and classified according to the functional trophic groups for associated insect fauna. A total of 904 Anopheles larvae were collected and distributed into five species. Density data and larval reduction demonstrated the rapid effect of the biolarvicide 24 h after application. A total of 4874 associated aquatic insects belonging to six orders and 23 families were collected. Regression analysis of diversity and richness indicated that the application of the biolarvicide had no influence on these indices and thus no effect on the associated insect fauna for a period of 30 days. B. sphaericus was found to be highly effective against the larvae of Anopheles, eliminating the larvae in the first days after application, with no effect on the associated insect fauna present in the fish ponds analyzed.