Seasonal and longitudinal variation in fish assemblage structure along an unregulated stretch of the Middle Uruguay River

Massaro, Marthoni Vinicius; Pachla, Lucas Adriano; Bastian, Rodrigo; Pelicice, Fernando Mayer; Reynalte‐Tataje, David Augusto

doi:10.1590/1982-0224-20190043

Cited by 7 publications

(7 citation statements)

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“…Juveniles probably disperse to other reaches, where recruitment is limited by river regulation, pollution and deforestation (Zaniboni‐Filho & Schulz, 2003; Reynalte‐Tataje et al, 2012; Lopes et al, 2019a). In fact, Mounic‐Silva et al (2019) recorded more juveniles in the Middle than in the Upper Uruguay, and Massaro et al (2019) reported high diversity and abundance of migratory fishes in this river segment.…”

Section: Discussionmentioning

confidence: 97%

“…Contrasting with other main rivers of the La Plata basin (Paraguay and Paraná rivers), the Uruguay is substantially channelized with limited development of floodplains and wetlands, which are formed mainly by the confluence with some tributaries. However, studies have reported the presence of migratory fish, with evidence of regional recruitment (Zaniboni‐Filho & Schulz, 2003; Reynalte‐Tataje et al, 2012; Massaro et al, 2019), including the location of spawning sites and the drift of eggs and larvae (Côrrea et al, 2011; Ávila‐Simas, Reynalte‐Tataje & Zaniboni‐Filho, 2014; Pachla et al, 2020; Reynalte‐Tataje et al, 2020). Fish recruitment dynamics, however, remain poorly understood, in particular because the location of nursery grounds remains unknown.…”

Section: Introductionmentioning

confidence: 99%

“…900 km) that may constitute an important site for fish recruitment in the basin. The existence of a small floodplain area near the confluence with the Ibicuí River (Massaro et al, 2019), for example, points to the possible existence of a nursery ground. However, no study has investigated the distribution of young migratory fish in the basin, or the nursery role of the main channel, tributaries and floodplain.…”

Section: Introductionmentioning

confidence: 99%

“…650 km) characterized by different hydro‐geomorphological conditions and landscape structure, i.e. the presence of channels, pools, tributaries and a small floodplain area (Massaro et al, 2019; Pachla et al, 2020). In particular, the study investigated spatial variations in the abundance, composition and size structure of juvenile fish among different sites along the river, comparing the main channel with tributaries.…”

Section: Introductionmentioning

confidence: 99%

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Recruitment of migratory fish in free‐flowing rivers with limited floodplain development

Pachla

Hartmann

Massaro

et al. 2022

Aquatic Conservation

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1. Hydrological connectivity is a basic feature of river ecosystems, responsible for important ecological processes. Human activities, however, have progressively modified natural connectivity, threatening the maintenance of aquatic biodiversity.2. Neotropical potamodromous fish depend heavily on fluvial connectivity to complete their life cycles. However, important ecological aspects remain poorly understood, especially in river systems with limited floodplain development (i.e. channelized rivers and drylands), where the environment poses constraints to fish recruitment. The Uruguay River Basin is such a system, with several migratory fish, small floodplain areas, and limited information about recruitment dynamics and nursery grounds. 3. The lack of information on critical habitats limits conservation and management actions, especially in scenarios of increasing environmental degradation and river regulation. This study investigated recruitment dynamics of migratory fishes in the Middle Uruguay River, a long fluvial segment targeted for hydropower development. The study investigated spatial variations in the abundance, composition and size structure of juvenile fish among different sites along an extensive fluvial gradient (ca. 650 km), comparing the main channel with tributaries.4. Juveniles of migratory fish were widely distributed in the region, totalling nine species, with a predominance of Characiformes. Spatial distribution was variable among species and size classes, with a differential use of tributaries, wetlands and the main channel. Juvenile composition differed between sampling sites and environments, and was correlated with different limnological and spatial variables.Greater abundances occurred in the mouth of a tributary where a small floodplain develops during the wet season.5. The results emphasize the importance of fluvial connectivity for fish migration, dispersal and recruitment, providing valuable information about migratory fishes in river systems with limited wetland development. These findings have significance for the management and conservation of migratory fish under scenarios of hydropower expansion, as comprehensive studies on recruitment are rare in free-flowing rivers.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Recruitment of migratory fish in free‐flowing rivers with limited floodplain development

Pachla

Hartmann

Massaro

et al. 2022

Aquatic Conservation

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“…Nesse sentido, pode-se considerar que este indivíduo seja potencialmente um dispersor. Contudo, ressalta-se que próximo ao trecho do registro o rio Uruguai possui uma largura aproximada de 1250 m (Massaro et al, 2019), podendo agir como barreira física para esta espécie. Ainda, a região do registro está inserida no bioma Pampa, caracterizado por vastas planícies, vegetação campestres, e pelo clima mesotérmico, subtropical com verões quentes sem seca definida e invernos rigorosos (Köppen, 1936;Alvares et al, 2013).…”

Section: Annexunclassified

Untitled

2021

Edentata: The Newsletter of the IUCN/SSC Anteater, Sloth and Ar

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Dorsal carapace and osteoderm morphological features have traditionally been widely used in both extinct and extant armadillo systematics. However, the intraspecific variability at the carapace level represents a little studied aspect. In this contribution, we analyzed several dorsal carapaces of Priodontes maximus with the purpose of recording such variability. As a result, we describe a total of seven structures concerning the dorsal carapace osteoderm configuration, including distinct terminations of the osteoderm rows, and the most frequent aberrant shapes of the osteoderms. Though the same type of structure can be usually found in several specimens, its frequency and precise location within the carapace are unique to each individual. In this sense, besides improving anatomical descriptions, the identification of these structures can be potentially implemented as a complementary method to help recognize specific individuals being tracked. Moreover, it can represent a very effective recognition method even a long time after death. Given the general decreasing trend of P. maximus populations, it is important to develop as many monitoring tools as possible, in order to support conservation programs for this species.

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Fish assemblage structure and habitat relationships of a large floodplain river in western North America

Williams,

Gregory,

Wildman

2024

River Research & Apps

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Understanding complex river floodplains is critical to conserve species of fish and their ecological functions. In 2011 through 2013, longitudinal gradients in fish assemblage were investigated in the Willamette River in western United States. Of 36,586 individual fish collected, 93% were native and 7% non‐native. The best predictors of fishes collected with a boat electrofisher were percent embeddedness, macrophytes, longitudinal river distance, average depth, and velocity. Habitat type (mainstem or slough) was also a significant predictor. The best predictor of fishes collected in nearshore habitats with a backpack electrofisher were longitudinal river distance, velocity, and percent embeddedness. Fish communities differed significantly between mainstem and slough habitat. Overall, 25 of 40 species had high fidelities to mainstem or slough habitats. Native species showed a high fidelity to both mainstem and slough habitats while non‐native species were significantly related only to slough habitats. Environmental characteristics strongly influenced fish assemblage structure in this large floodplain river. Maintaining and restoring mainstem and off‐channel habitats are critical for maximizing native species resilience in the face of non‐native species encroachment and a changing environment. Restoring the natural flow regime to the degree possible is needed to increase connectivity between the floodplain and mainstem and provide thermal and flood refuges for native fishes. Understanding habitat relationships provides essential context for fish conservation and management by resource agencies and landowners.

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Seasonal and longitudinal variation in fish assemblage structure along an unregulated stretch of the Middle Uruguay River

Cited by 7 publications

References 46 publications

Recruitment of migratory fish in free‐flowing rivers with limited floodplain development

Recruitment of migratory fish in free‐flowing rivers with limited floodplain development

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Fish assemblage structure and habitat relationships of a large floodplain river in western North America

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