Geology topics

Maristela Cavicchioli Makrakis

Publications and source records attributed to Maristela Cavicchioli Makrakis.

6 recordsLinked to original sources

USGS2019

Tributaries as biodiversity preserves: An ichthyoplankton perspective from the severely impounded Upper Paraná River

Conservation of fish assemblages in severely impounded rivers has often focused on providing longitudinal and lateral connectivity along the main stem. Less attention has been given to tributaries, some of which remain unimpounded. This study shows that the biodiversity of ichthyoplankton in tributaries to the largest reservoir in the Paraná River, Brazil, is similar to that of tributaries of the few remaining unimpounded stretches of the Paraná River. Annual and seasonal variability in discharge within and among tributaries attracts and supports a diverse mix of species in each spawning season. Tributaries enrich the fish biodiversity of the entire system by providing a variety of environmental conditions, access to spawning habitat, refugia for early life stages, and by promoting ecological heterogeneity. Thus, tributaries can mitigate the adverse influence of an impounded main stem. Tributaries also support populations of endangered and threatened species. A focus on tributaries offers conservation alternatives that are more feasible given the scale and large number of impoundments constructed on the main stem. Conservation in the main stem may focus on maintaining passage through dams and access to large floodplains. Conversely, in tributaries conservation may focus on managing the quality of inflows from catchments, preserving suitable instream habitats and flows, and preserving access to smaller but more numerous floodplains.

Paranas River↗

USGS2018

Effectiveness of a fish ladder for two Neotropical migratory species in the Paraná River

We evaluated fish ladder effectiveness at Porto Primavera Dam in the Upper Paraná River, for two Neotropical migratory fish species. Overall, 564 fish (448 Megaleporinus obtusidens and 116 M. piavussu ) were PIT-tagged, released in upstream and downstream areas (on the left and right banks), and monitored continuously for 4 years. The fish performed two-way movements through the fish ladder, ascending from the tailrace and descending from the forebay. We registered 46 M. obtusidens (10.3%) and only 3 M. piavussu (2.6%) from the fish ladder, therefore all analyses were focused on M. obstusidens . Entry proportion ranged from 0 to 48.1% depending on release site and was greatest for fish released downstream near the fish ladder entrance. Entry times ranged from 3.0 to 384.0 days, and median times were 32.9 and 25.8 days for downstream and upstream, respectively. Of fish that entered the fish ladder, passage percentages were 80% for fish release downstream and 100% for fish released upstream, and median transit time was 0.7 and 0.9 hours, respectively. Results suggest that if guidance and entry conditions can be improved, this fish ladder design holds promise as an effective solution for providing passage in both directions.

Marine and Freshwater Research↗

USGS2014

Importance of reservoir tributaries to spawning of migratory fish in the upper Paraná River

Regulation of rivers by dams transforms previously lotic reaches above the dam into lentic ones and limits or prevents longitudinal connectivity, which impairs access to suitable habitats for the reproduction of many migratory fish species. Frequently, unregulated tributaries can provide important habitat heterogeneity to a regulated river and may mitigate the influence of impoundments on the mainstem river. We evaluated the importance of tributaries to spawning of migratory fish species over three spawning seasons, by comparing several abiotic conditions and larval fish distributions in four rivers that are tributaries to an impounded reach of the Upper Parana River, Brazil. Our study confirmed reproduction of at least 8 long-distance migrators, likely nine, out of a total of 19 occurring in the Upper Parana River. Total larval densities and percentage species composition differed among tributaries, but the differences were not consistent among spawning seasons and unexpectedly were not strongly related to annual differences in temperature and hydrology. We hypothesize that under present conditions, densities of larvae of migratory species may be better related to efficiency of fish passage facilities than to temperature and hydrology. Our study indicates that adult fish are finding suitable habitat for spawning in tributaries, fish eggs are developing into larvae, and larvae are finding suitable rearing space in lagoons adjacent to the tributaries. Our findings also suggest the need for establishment of protected areas in unregulated and lightly regulated tributaries to preserve essential spawning and nursery habitats.

River Research and Applications↗

USGS2012

Culverts in paved roads as suitable passages for neotropical fish species

Improperly installed or poorly maintained culverts can pose a serious threat to fish by disrupting their habitat and endangering spawning success. Road culverts that are not designed for fish passage frequently can become obstacles. This can be especially problematic for migratory species, but can lead to fragmentation of resident populations as well. This study evaluated 40 culverts of 29 sites within a 25-km radius from Toledo city, Paraná State, southern Brazil, with respect to their likely effects on movement of the local ichthyofauna. We collected data on the shape and length of culverts, culvert material, waterfall height, water column depth, slope, and estimated flow velocity. Culverts were categorized by level of barrier risk for upstream migration: high, medium, low, and impassable, as well as the type of barrier posed (fall height, depth, length and velocity). Most of culverts analyzed were considered potential barriers to fish movement, with 45% classified as impassible, 45% as high risk, 10% as medium risk, and no culverts as low risk. Brazilian culverts as fishways will require additional monitoring and studies to corroborate the premises proposed in the present study. Road culvert projects that are properly built and maintained will be able to simultaneously improve function of roadways and protect fish populations.

Parana↗

USGS2012

Passage performance of long-distance upstream migrants at a large dam on the Paraná River and the compounding effects of entry and ascent

This paper presents results of a fishway evaluation performed at the Engenheiro Sérgio Motta Hydroelectric Power Plant (known as Porto Primavera) - CESP, Paraná River, Brazil. The evaluation was designed to quantify entry and passage proportions of 4 long-distance migratory fish species: Brycon orbignyanus (piracanjuba), Piaractus mesopotamicus (pacu), Prochilodus lineatus (curimba), and Rhinelepis aspera (cascudo-preto). Proportions finding and entering the fishway differed between species, ranged from 7.4 % (Prochilodus lineatus) to 55.4% (Piaractus mesopotamicus). Also, proportion passing was different between species, ranged from 31% (R. aspera) to 100% (Prochilodus lineatus). Fish that were marked and released within the fishway had greater failure rates than those that entered volitionally. Total time to pass ranged from 1.48 hours (Prochilodus lineatus) to 178.9 hours (R. aspera). Failure rates were greatest in the lower end of the fishway. Although some individuals of all species passed successfully, significant challenges remain to restoring connectivity of the upper Paraná River.

SÃ¡o Paulo States↗

USGS2012

Spawning and nursery habitats of neotropical fish species in the tributaries of a regulated river

This chapter provides information on ontogenetic patterns of neotropical fish species distribution in tributaries (Verde, Pardo, Anhanduí, and Aguapeí rivers) of the Porto Primavera Reservoir, in the heavily dammed Paraná River, Brazil, identifying key spawning and nursery habitats. Samplings were conducted monthly in the main channel of rivers and in marginal lagoons from October through March during three consecutive spawning seasons in 2007-2010. Most species spawn in December especially in Verde River. Main river channels are spawning habitats and marginal lagoons are nursery areas for most fish, mainly for migratory species. The tributaries have high diversity of larvae species: a total of 56 taxa representing 21 families, dominated by Characidae. Sedentary species without parental care are more abundant (45.7%), and many long-distance migratory fish species are present (17.4%). Migrators included Prochilodus lineatus , Rhaphiodon vulpinus , Hemisorubim platyrhynchos , Pimelodus maculatus , Pseudoplatystoma corruscans , Sorubim lima , two threatened migratory species: Salminus brasiliensis and Zungaro jahu , and one endangered migratory species: Brycon orbignyanus . Most of these migratory species are vital to commercial and recreational fishing, and their stocks have decreased drastically in the last decades, attributed to habitat alteration, especially impoundments. The fish ladder at Porto Primavera Dam appears to be playing an important role in re-establishing longitudinal connectivity among critical habitats, allowing ascent to migratory fish species, and thus access to upstream reaches and tributaries. Establishment of Permanent Conservation Units in tributaries can help preserve habitats identified as essential spawning and nursery areas, and can be key to the maintenance and conservation of the fish species in the Paraná River basin.

Upper Paraná River↗