Papers by Rodrigo Ferreira Bastos
Check List, Oct 1, 2009
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South American Journal of Herpetology
Abstract. Trophic subsidy is an ecological process consisting in the transference of nutrients be... more Abstract. Trophic subsidy is an ecological process consisting in the transference of nutrients between adjacent habitats, allowing the occupancy of less productive habitats by several species. We tested for the existence of trophic subsidy provided by aquatic plants of temporary ponds in maintaining individuals of the sand dune lizard Liolaemus occipitalis in southern Brazil. This lizard is a sit-and-wait predator restricted to coastal sand dunes. As these sand dunes occur in a mosaic of temporary ponds, we hypothesized the existence of a nutritional/energetic dependence of lizards from adjacent aquatic habitats. Our evaluation was based on carbon and nitrogen stable isotope analysis in association with gut content analysis of lizards sampled along an entire inundation cycle. Stomach contents revealed no seasonal variation in consumed prey item composition. Nevertheless, we detected changes in prey group composition. The volumetric contribution of Diptera increased over inundation classes (increase = 5%; peak = 61%). Carbon and nitrogen stable isotope ratios indicated that the L. occipitalis trophic web is mainly maintained by terrestrial sources. Isotope ratios also indicated the existence of aquatic contributions to tissue formation, but, despite its tendency to increase over the inundation process (10.7–13.3%), this trend lacks statistical support. We conclude that the studied population of L. occipitalis partially depends on trophic subsidy from aquatic sources and that any conservation plan for this endangered lizard species should take into account the preservation of non-habitats like temporary ponds.
Ecological Indicators, 2017
Jenynsia! multidentata, that! reveals! dietary! variation! among! locations! across! a! salinity!... more Jenynsia! multidentata, that! reveals! dietary! variation! among! locations! across! a! salinity! gradient! of! a! coastal! lagoon! in! southern! Brazil.! We! also! compared! estimates! of! foods! ingested! vs.! foods! assimilated.! Food! assimilation! was estimated! using! carbon! (ı 13 C)! and! nitrogen! (ı 15 N)! stable! isotope! ratios! of! food! sources! and! consumer muscle! tissue! and! an! isotopic! mixing! model! (SIAR);! consumer! trophic! position! (TP)! was! estimated! from consumer! and! production! source! ı 15 N! values.! Diet! was! estimated! using! an! index! of! relative! importance based! on! frequency! of! occurrence! and! volumetric! and! numeric! proportions! of! food! items! from! stomach contents.! The! effect! of! variation! in! TDF! on! food! assimilation! and! TP! was! tested! using! three! alternative! TDFs reported! in! review! papers.! We! then! created! a! new! method! that! used! food! source-specific! TDFs! (reported separately! for! herbivores! and! carnivores
Brazilian Journal of Biology, 2012
Pseudis minuta is abundant in a variety of aquatic environments of the Pampa domain. Therefore, i... more Pseudis minuta is abundant in a variety of aquatic environments of the Pampa domain. Therefore, it can be considered a good model for testing hypotheses on environmental heterogeneity and the influence of climate on the activity of anurans. In this study, we examined the spatial distribution pattern of P. minuta in terms of microhabitats and the influence of abiotic factors on seasonal fluctuations in the abundance of this species. Samples were collected monthly from April 2008 to May 2009 in wetlands and coastal dunes in the Lagoa do Peixe National Park. A total of 112 specimens of P. minuta were collected, of which 45 were found in the wetland area and 67 in the dune area. The species showed seasonal fluctuation in abundance, and it was most abundant in months with higher temperatures (spring-summer). Pseudis minuta was mainly associated with aquatic vegetation, an expected pattern in terms of their morphological adaptations to this environment. Among the abiotic parameters analyz...
Neotropical Ichthyology, 2011
Despite the importance of the pearl cichlid Geophagus brasiliensis for the aquarium fish trade wo... more Despite the importance of the pearl cichlid Geophagus brasiliensis for the aquarium fish trade worldwide and its wide distribution, many aspects of its biology, such as the relationships between its feeding ecology and reproductive behavior, are not fully understood in natural conditions on its native habitat. In this paper, we investigated its diet focusing on how differences in diet and food consumption are related to differences in gender and sexual maturity. The digestive tract of each individual was dissected and had its content analyzed, whereas each gonad was microscopically analyzed to determine gender (male/female) and sexual maturity (immature/mature). A total of 28 females and 31 males were analyzed. Mature individuals were more common than immature specimens both for males (64.50%) and females (64.30%). The analysis of 52 individuals with non-empty digestive tracts revealed a diet comprised of 27 items. According to the Index of Alimentary importance (%IAi), the most imp...
Hydrobiologia, 2013
ABSTRACT This work investigated variations in fish guilds along marine surf zone to freshwater re... more ABSTRACT This work investigated variations in fish guilds along marine surf zone to freshwater reaches of coastal plain streams and their relationships with environmental factors. Fish and abiotic data were collected monthly during 1 year and an automatic image-recording system was used to monitor marine intrusion events. Aside ephemeral salinity gradients produced by storm surges, freshwater conditions prevailed inside streams. Despite of that, fish habitat use guilds were spatially distributed according to their salinity tolerance, with marine species occurring mainly in the stream site near the adjacent surf zone and non-salinity tolerant freshwater fish in the upstream site. Marine intrusion was the main factor correlated with the entrance of marine-related fish into streams during summer. In contrast, higher rainfall during colder months prevented the dominance of marine species. This work highlighted that spatial segregation in fish habitat use guild could occur even in the absence of long-lasting salinity gradients, since active colonization by euryhaline fish and sporadic marine intrusions can lead to the occurrence of marine-related fish in coastal plain streams. Future studies should evaluate if this marine intrusion role on fish of coastal plain streams would be affected by changes in sea level and rainfall in a global warming scenario.
Aquatic Biology, 2014
In higher latitudes of the northern hemisphere, anadromous fishes can act as biological vectors, ... more In higher latitudes of the northern hemisphere, anadromous fishes can act as biological vectors, moving marine-derived nutrients into freshwater ecosystems during their reproductive migration. Much less information is available on the potential role of marine and estuarinerelated fishes as biological vectors in subtropical latitudes. Here, we investigated whether mullet juveniles might transport marine nutrients into the freshwater food webs of coastal streams in southern Brazil (32°17'S, 52°15'W). To test this hypothesis, we analyzed the stable isotope ratios of carbon (δ 13 C) and nitrogen (δ 15 N) in 10 basal production sources and 10 consumer species, including juvenile mullets, at 3 sites (surf zone, lower stream reach, headwater reach) along a marine−freshwater gradient. Our results revealed a significant decreasing trend in δ 15 N and δ 13 C values from the sea to the freshwater sites, suggesting an importation and incorporation of marine-derived nutrients into the coastal stream. A mixing model showed a marked shift in assimilation from marine to freshwater production sources by mullet Mugil liza juveniles as they moved from the surf zone into the coastal stream (lower stream and headwater reaches). Our mixing model also indicated that material of marine origin is assimilated by freshwater predators, particularly those found at the lower stream reach. Further experimental and field work is needed to evaluate the implications of marine-derived carbon and nitrogen transport by juvenile mullets for the structure and dynamics of food webs in coastal streams.
Anais da Academia Brasileira de Ciências, 2021
Eutrophic estuaries receive organic matter (OM) inputs from multiple sources. This study evaluate... more Eutrophic estuaries receive organic matter (OM) inputs from multiple sources. This study evaluated the distribution and origin of sedimentary OM in an eutrophic estuary (Pina Sound, NE Brazil). Thirteen samples were collected in the sublittoral in addition to major local sources. Biochemical (chlorophyll-Chl), elemental [(C/N) a and C/S ratios] and isotopic (δ 15 N and δ 13 C) analyses were carried out for characterizing OM and redox conditions. The SIAR mixing model was used to quantify contribution from main sources. At Pina Sound, distribution of OM is associated with mud, refl ecting the hydrodynamics control on deposition of suspended particles. Microphytobenthic production is limited ([Chl a] < 1000 µg/g organic carbon) in the sublittoral where the Chl degradation products prevail (mean [Pheopigments] = 2643 ± 958 µg/g organic carbon). Anoxic conditions (C/S ratio ≈ 2) are typically observed in sediments of deeper portions of Pina Sound. Such sediments receive high organic loads and are subject to poor water renewal. According to SIAR mixing model, sedimentary OM of Pina Sound is composed of, on average: 50% phytoplankton, 24% sewage and 26% C 3 plants. This refl ects fertilization of Pina Sound with high loads of untreated sewage. Pina Sound has a great potential to retain sewage-derived OM.
Estuarine, Coastal and Shelf Science
Aquatic ecosystems exchange nutrients and organic matter with surrounding terrestrial ecosystems,... more Aquatic ecosystems exchange nutrients and organic matter with surrounding terrestrial ecosystems, and floods import allochthonous material from riparian areas into fluvial systems. We surveyed food web components of a wetland and shallow lake in a subtropical coastal region of Brazil to examine how community trophic structure and the entrance of allochthonous material into the food web were affected by floods. Stable isotope analysis was performed for samples of terrestrial and aquatic basal production sources and aquatic animals to trace the origin of organic matter assimilated by aquatic animals and estimate vertical trophic positions and food chain length. Lake and wetland trophic structures were compared for cool/wet and warm/dry seasons. Food web structure was hypothesized to differ based on hydrology, with the more stable lake having greater food web complexity, and seasonal flooding resulting in greater allochthonous inputs to the aquatic food web. We compared spatial and tem...
Uma questao central no entendimento da ecologia aquatica e a origem e o fluxo de materia e energi... more Uma questao central no entendimento da ecologia aquatica e a origem e o fluxo de materia e energia nas teias alimentares. Diversas hipoteses e teorias tentam explicar (1) os diferentes niveis de contribuicao da producao nos ambientes terrestres (2) os diferentes comprimentos de cadeia trofica entre diferentes porcoes e diferentes tipos de ambientes aquaticos. Ha cerca de 60 anos, as razoes isotopicas dos componentes das tramas troficas, principalmente carbono (δ13C) e nitrogenio (δ15N), tem sido empregadas para identificar e quantificar as relacoes entre eles. O carbono proporciona a identificacao das fontes de materia, pois sua razao isotopica muda pouco entre o consumidor e o recurso. Ja o nitrogenio propicia a oportunidade de mensuracao das posicoes troficas dos consumidores, uma vez que sua razao isotopica muda de maneira similar entre um nivel trofico e o subsequente. Desde entao, diversas tecnicas analiticas emergiram para a superacao dos pressupostos e limitacoes no uso dos i...
Journal of Applied Ichthyology
Marine Ecology Progress Series
Resource pulsing is a widespread phenomenon, but its effects on ecosystem dynamics are often diff... more Resource pulsing is a widespread phenomenon, but its effects on ecosystem dynamics are often difficult to predict. Hydrological pulsing, in particular, is known to influence the structure and dynamics of fluvial and coastal ecosystems, but little information is available about its effects on trophic connectivity between wetlands and estuaries. We investigated the hypothesis that hydrologic pulsing drives 1-way trophic subsidies (e.g. suspended organic matter and freshwater fish) from wetland to estuary. Our study system is a coastal lagoon with an ephemeral mouth that, when closed, stores freshwater as a sustained flood pulse that is subsequently released when a connection with the sea is reestablished. We monitored isotopic composition of consumers and food sources over the course of an entire flood pulse to infer trophic linkages and spatial subsidies. Before the flood peak (April and May), freshwater and estuarine zones were largely dependent on local primary production sources (seston and C 3 plants vs. C 4 plants and microphytobenthos, respectively), essentially functioning as disconnected compartments. A sustained pulse of freshwater inflow (June to August) induced greater habitat connectivity and a net flow of biomass and energy from the freshwater zone into the estuarine zone. The opening of the lagoon outlet channel abruptly terminated the flood pulse and reduced freshwater subsidies to estuarine consumers, and both zones returned to dependence on autochthonous production. Our findings contribute to current concerns that artificial opening of sandbars in coastal lagoons alters natural ecological dynamics with significant effects on biodiversity and ecosystem processes.
Pan American Journal of Aquatic Sciences, 2013
We studied three coastal streams (washouts) in southern Brazil. We found 41 fish species, of whic... more We studied three coastal streams (washouts) in southern Brazil. We found 41 fish species, of which, Dormitator maculatus, Eleotris pisonis, Austrolebias minuano (endangered) and Lutjanus cyanopterus (endangered) had their austral distribution limits extended.
Iheringia. Série Zoologia, 2013
Characidium rachovii (Regan, 1913) é uma espécie frequente em riachos da planície costeira do est... more Characidium rachovii (Regan, 1913) é uma espécie frequente em riachos da planície costeira do estado do Rio Grande do Sul, sul do Brasil. Entretanto, seu nicho trófico é ainda desconhecido. O presente trabalho teve como objetivos: (i) descrever a dieta de C. rachovii de três riachos costeiros do RS; (ii) avaliar a influência de um ecótono (mar-riacho) na dieta, comparando dois locais, um próximo do mar e outro distante, e (iii) avaliar o efeito do número de indivíduos analisados na riqueza da dieta. A análise do conteúdo estomacal de 139 indivíduos revelou que a espécie é especializada no consumo de Diptera (estágio aquático) e Amphipoda. Ao mesmo tempo, pode-se considerar que C. rachovii apresentou hábito alimentar oportunista, já que, apesar de tal preferência, consumiu grande riqueza de recursos (24 itens), vários deles em baixa frequência e alta abundância. Não houve diferenças na composição da dieta entre os riachos e locais. A riqueza esperada (rarefação) mostrou que o número ...
A key factor for estimates of assimilation of resources and trophic position based on stable isot... more A key factor for estimates of assimilation of resources and trophic position based on stable isotope data is the trophic discrimination factor (TDF). TDFs are assumed based on literature reviews, but may vary depending on a variety of factors, including the type of diet. We analyzed effects of alternative TDFs on estimates of assimilated resources and trophic positions for an omnivorous fish, Jenynsia multidentata, that reveals dietary variation among locations across a salinity gradient of a coastal lagoon in southern Brazil. We also compared estimates of foods ingested vs. foods assimilated. Food assimilation was estimated using carbon (ı 13 C) and nitrogen (ı 15 N) stable isotope ratios of food sources and consumer muscle tissue and an isotopic mixing model (SIAR); consumer trophic position (TP) was estimated from consumer and production source ı 15 N values. Diet was estimated using an index of relative importance based on frequency of occurrence and volumetric and numeric proportions of food items from stomach contents. The effect of variation in TDF on food assimilation and TP was tested using three alternative TDFs reported in review papers. We then created a new method that used food source-specific TDFs (reported separately for herbivores and carnivores) weighted in proportion to estimated assimilation of resources according to mixing model estimates to estimate TP (hereafter TP WAR). We found that plant material was not assimilated in a proportion similar to its importance in the diet of fish at a freshwater site, and the new method yielded best assimilation estimates. Animal material made greatest contributions to fish biomass irrespective of TDFs used in the mixing model. The new method produced TP estimates consistent with differences in estimated food assimilation along the salinity gradient. Our findings support the idea that food source-specific TDFs should be used in trophic studies of omnivores, since the method improved our ability to estimate trophic position and resource assimilation, two important ecological indicators.
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Papers by Rodrigo Ferreira Bastos