Identification of key microhabitats for fish assemblages in tropical Brazilian savanna streams

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Grass-dominated stream sites exhibit low fish species diversity and dominance by guppies: an assessment of two tropical pasture river basins

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The fish fauna in tropical rivers: The case of the Sorocaba river basin, São Paulo, Brazil

A survey was carried out on the fish species in the Sorocaba River basin, the main tributary of the left margin of the Tietê River, located in the State of São Paulo, Brazil. The species were collected with gill nets. After identification of the specimens, their relative abundance, weight and standard length were determined. Up to the present moment there are not any studies that focus this subject in this hydrographic basin. Fifty-three species, distributed in eighteen families and six orders were collected. Characiformes were represented by twenty-eight species, Siluriformes by seventeen species, the Gymnotiformes by three species, Perciformes and Cyprinodontiformes by two species, and the Synbranchiformes by one species. Among the collected species there were two exotic. The most abundant species were Astyanax fasciatus and Hypostomus ancistroides. In relation to total weight the most representative species were Hoplias malabaricus and Hypostomus ancistroides. Cyprinus carpio, Prochilodus lineatus, Schizodon nasutus and Hoplias malabaricus were the most representative species in relation to average weight. Largest standard length were recorded for Sternopygus macrurus, Steindachnerina insculpta, Eigenmannia off. virescens and Cyprinus carpio.

Longitudinal patterns of fish assemblages in mountain streams from tropical forest biome

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Defining a fish bio-assessment tool to monitoring the biological condition of a cascade reservoirs system in tropical area

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The influence of habitat homogenization on the trophic structure of fish fauna in tropical streams

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Photoperiod modulation of aggressive behavior is independent of androgens in a tropical cichlid fish

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The fish fauna in tropical rivers: The case of the Sorocaba river basin, Sao Paulo, Brazil

A survey was carried out on the fish species in the Sorocaba. River basin, the main tributary of the left margin of the Tiete River, located in the State of Sao Paulo, Brazil. The species were collected with gill nets. After identification of the specimens, their relative abundance, weight and standard length were determined. Up to the present moment there are not any studies that focus this subject in this hydrographic basin. Fifty-three species, distributed in eighteen families and six orders were collected. Characiformes were represented by twenty-eight species, Siluriformes by seventeen species, the Gymnotiformes by three species, Perciformes and Cyprinodontiformes by two species, and the Synbranchiformes by one species. Among the collected species there were two exotic. The most abundant species were Astyanax fasciatus and Hypostomus ancistroides. In relation to total weight the most representative species were Hoplias malabaricus and Hypostomus ancistroides. Cyprinus carpio, Prochilodus lineatus, Schizodon nasutus and Hoplias malabaricus were the most representative species in relation to average weight. Largest standard length were recorded for Sternopygus macrurus, Steindachnerina insculpta, Eigenmannia aff. virescens and Cyprinus carpio.

More of the same: high functional redundancy in stream fish assemblages from tropical agroecosystems

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Reports on the scientific results of the expedition to the tropical Pacific by the U.S. Fish commission steamer "Albatross," from August, 1899, to March, 1900. I. Preliminary report and list of stations.

Mode of access: Internet.

Silica reduces the toxicity of aluminium to a tropical freshwater fish (Mogurnda mogurnda)

The toxicity of aluminium (Al) to fish in acidic waters has been well documented. It was therefore expected that Al toxicity would be significant in fish communities in Gadjarrigamarndah (Gadji) Creek, a seasonally flowing stream in tropical northern Australia. This creek receives acidic groundwater containing elevated concentrations of Al from earlier land irrigation of treated mine tailings water from the former Nabarlek uranium mine. It was hypothesised that Al toxicity was reduced by high levels of silica (Si) in the water, and the subsequent formation of Al-silicate complexes. This prompted a laboratory assessment of the toxicity of Gadji Creek water to sac-fry of the native fish, Mogurnda mogurnda, followed by more detailed investigation of the toxicity of Al and the influence of Si in reducing Al toxicity. No mortality of M. mogurnda sac-fry was observed in two toxicity tests using Gadji Creek water collected in August 1997 and September 1998. The majority of Al (80-95%) was calculated to be complexed with humic substances and sulfate, with <1% being complexed with silicate. Assessment of the influence of silica on the acute toxicity of Al in the absence of natural organic complexants (i.e. in reconstituted freshwater, pH 5) revealed that Si reduced Al toxicity. As the molar ratio of Si:Al was increased, the percent survival of M. mogurnda sac-fry increased until there was no significant (P > 0.05) difference from the controls. However, speciation modelling again predicted that little (<3%) Al complexed with silicate, with the speciation and bioavailability of Al remaining constant as the molar ratio of Si:Al increased. Therefore, the original hypothesis that Al-silicate complexes in solution reduced the toxicity of Al to M. mogurnda could not be supported. This potential mechanism, and an alternative hypothesis, that Si competes with Al for binding sites at the fish gill surface, requires further investigation. Crown Copyright (C) 2002 Published by Elsevier Science Ltd. All rights reserved.

Fine tuning for the tropics: application of eDNA technology for invasive fish detection in tropical freshwater ecosystems

Invasive species pose a major threat to aquatic ecosystems. Their impact can be particularly severe in tropical regions, like those in northern Australia, where >20 invasive fish species are recorded. In temperate regions, environmental DNA (eDNA) technology is gaining momentum as a tool to detect aquatic pests, but the technology's effectiveness has not been fully explored in tropical systems with their unique climatic challenges (i.e. high turbidity, temperatures and ultraviolet light). In this study, we modified conventional eDNA protocols for use in tropical environments using the invasive fish, Mozambique tilapia (Oreochromis mossambicus) as a detection model. We evaluated the effects of high water temperatures and fish density on the detection of tilapia eDNA, using filters with larger pores to facilitate filtration. Large-pore filters (20 μm) were effective in filtering turbid waters and retaining sufficient eDNA, whilst achieving filtration times of 2-3 min per 2-L sample. High water temperatures, often experienced in the tropics (23, 29, 35 °C), did not affect eDNA degradation rates, although high temperatures (35 °C) did significantly increase fish eDNA shedding rates. We established a minimum detection limit for tilapia (1 fish/0.4 megalitres/after 4 days) and found that low water flow (3.17 L/s) into ponds with high fish density (>16 fish/0.4 megalitres) did not affect eDNA detection. These results demonstrate that eDNA technology can be effectively used in tropical ecosystems to detect invasive fish species. © 2016 John Wiley & Sons Ltd.

The deep-sea fish Kali macrodon: a new record for the tropical eastern Atlantic off Cape Verde

A new deep-sea fish is reported for the tropical eastern Atlantic. The rare chiasmodontid Kali macrodon was caught for the first time in Cape Verdean waters during an oceanographic survey in September 2009. This record provides the fifth occurrence for the species in the north-eastern Atlantic and represents the third specimen ever caught in tropical waters.

Predator Crown-of-Thorns Starfish (Acanthaster planci) Outbreak, Mass Mortality of Corals, and Cascading Effects on Reef Fish and Benthic Communities

Outbreaks of the coral-killing seastar Acanthaster planci are intense disturbances that can decimate coral reefs. These events consist of the emergence of large swarms of the predatory seastar that feed on reef-building corals, often leading to widespread devastation of coral populations. While cyclic occurrences of such outbreaks are reported from many tropical reefs throughout the Indo-Pacific, their causes are hotly debated, and the spatio-temporal dynamics of the outbreaks and impacts to reef communities remain unclear. Based on observations of a recent event around the island of Moorea, French Polynesia, we show that Acanthaster outbreaks are methodic, slow-paced, and diffusive biological disturbances. Acanthaster outbreaks on insular reef systems like Moorea's appear to originate from restricted areas confined to the ocean-exposed base of reefs. Elevated Acanthaster densities then progressively spread to adjacent and shallower locations by migrations of seastars in aggregative waves that eventually affect the entire reef system. The directional migration across reefs appears to be a search for prey as reef portions affected by dense seastar aggregations are rapidly depleted of living corals and subsequently left behind. Coral decline on impacted reefs occurs by the sequential consumption of species in the order of Acanthaster feeding preferences. Acanthaster outbreaks thus result in predictable alteration of the coral community structure. The outbreak we report here is among the most intense and devastating ever reported. Using a hierarchical, multi-scale approach, we also show how sessile benthic communities and resident coral-feeding fish assemblages were subsequently affected by the decline of corals. By elucidating the processes involved in an Acanthaster outbreak, our study contributes to comprehending this widespread disturbance and should thus benefit targeted management actions for coral reef ecosystems.

Developing sustainable fish farming in the Western Pacific : a viewpoint on potential reasons for why many attempts failed

Capture fisheries and aquaculture have been a major source of food and providers of economic benefits to many communities around the world for a very long time. While the history of aquaculture or fish farming can be traced back for more than 2000 years in some corners of the globe, notably in China, Japan and the Mediterranean, this is not true everywhere, where in general, fish farming is a relatively new industry. Rapid human population growth and increasing urbanisation over the last 20 to 40 years has meant that while fish consumption has doubled globally, returns from capture fisheries have remained static or have declined due to overexploitation and rising pollution levels, with some fisheries either closing or becoming economically unviable. Data from studies suggest that this trend is unlikely to be reversed unless appropriate fisheries management allows depleted wild stocks to rebuild. This has occurred during a time when demand for fish products has grown, in part due to improved purchasing power in some developing countries and changing dietary habits where fish are now considered to have a positive impact on health. Based on the projected population growth over the next two decades, Food and Agricultural Organization (FAO) estimates that at least an additional 40 million tonnes of aquatic food will be required to maintain the current per capita consumption (FAO 2006).