Topic
Sandelia
About: Sandelia is a research topic. Over the lifetime, 4 publications have been published within this topic receiving 26 citations.
Papers
TL;DR: The hypothesis that stream fishes have a common response to environmental descriptors is rejected and the contrasting habitat associations of stream fishes considered in this study could be a reflection of their morphological divergence which may allow them to exploit specific habitats that differ in their environmental stressors.
Abstract: Knowledge of the factors that drive species distributions provides a fundamental baseline for several areas of research including biogeography, phylogeography and biodiversity conservation. Data from 148 minimally disturbed sites across a large drainage system in the Cape Floristic Region of South Africa were used to test the hypothesis that stream fishes have similar responses to environmental determinants of species distribution. Two complementary statistical approaches, boosted regression trees and hierarchical partitioning, were used to model the responses of four fish species to 11 environmental predictors, and to quantify the independent explanatory power of each predictor. Elevation, slope, stream size, depth and water temperature were identified by both approaches as the most important causal factors for the spatial distribution of the fishes. However, the species showed marked differences in their responses to these environmental variables. Elevation and slope were of primary importance for the laterally compressed Sandelia spp. which had an upstream boundary below 430 m above sea level. The fusiform shaped Pseudobarbus ‘Breede’ was strongly influenced by stream width and water temperature. The small anguilliform shaped Galaxias ‘nebula’ was more sensitive to stream size and depth, and also penetrated into reaches at higher elevation than Sandelia spp. and Pseudobarbus ‘Breede’. The hypothesis that stream fishes have a common response to environmental descriptors is rejected. The contrasting habitat associations of stream fishes considered in this study could be a reflection of their morphological divergence which may allow them to exploit specific habitats that differ in their environmental stressors. Findings of this study encourage wider application of complementary methods in ecological studies, as they provide more confidence and deeper insights into the variables that should be managed to achieve desired conservation outcomes.
21 citations
TL;DR: It was proposed that the current range of this lineage probably represent the only available habitats for the persistence of different life stages for this taxon, and immediate conservation measures should focus on preventing the spread on non-native invasive fishes, whereas future studies should evaluate the impacts of population fragmentation and identifying appropriate intervention measures to maintain this lineage's long-term adaptive potential.
Abstract: Sandelia bainsii is a range-restricted and highly threatened freshwater fish endemic to South Africa. Recent genetic evidence suggests that this species comprises three allopatrically distributed lineages that have been informally designated as Sandelia sp. "Kowie," Sandelia sp. "Keiskamma" and Sandelia sp. "Buffalo." As these lineages have only been recently identified and are likely to face a high risk of extinction because of restricted distributions, there is a critical need for generating ecological information to guide conservation prioritisation. The present study compared the historical and current distribution patterns, together with the habitat associations of Sandelia sp. "Kowie" in the Koonap and Kat rivers, tributaries of the Great Fish River. This study indicated that this lineage has been extirpated from one of the three localities in the Koonap River where it was historically abundant. In the Kat River, the current distribution of Sandelia sp. "Kowie" was comparable to its historical range, but its future persistence is threatened by the presence of non-native piscivores, instream physical barriers and potential future exploration for shale gas and infrastructure development in the Karoo Basin. A generalised hurdle negative binomial model revealed that although this lineage's probability of occurrence was high in habitats with boulder and sand substrates, and low conductivity, habitat characteristics were poor predictors of its abundance. Thus, it was postulated that the current range of this lineage probably represents the only available habitats for the persistence of different life stages for this taxon. Alternatively, the observed patterns may suggest the possibility of a shift in habitat associations, possibly for optimum utilisation of the remaining refugia within this river system. Immediate conservation measures should focus on preventing the spread on non-native invasive fishes, whereas future studies should evaluate the impacts of population fragmentation and identify appropriate intervention measures to maintain this lineage's long-term adaptive potential.
7 citations
TL;DR: In this article, the Baakens River, a small urban river that runs through the city of Port Elizabeth in the Eastern Cape of South Africa, was sampled using fyke nets, 8 sites were sampled along the river course over a 4-month period.
Abstract: Freshwater and marine-spawned fishes were sampled from the Baakens River, a small urban river that runs through the city of Port Elizabeth in the Eastern Cape of South Africa. Using fyke nets, 8 sites were sampled along the river course over a 4-month period (January – April 2014). Catches were comprised of indigenous freshwater, marine migrant and alien fishes. Marine migrant fishes, including catadromous species dependent on freshwater for early life-history strategies, were significantly affected by instream barriers which prohibited upstream migration of all species except Anguilla mossambica. The freshwater fish fauna was dominated by Tilapia sparrmanii and Pseudocrenilabrus philander, species that are alien to the Baakens River. While indigenous Barbus pallidus and Sandelia capensis were both abundant and widely distributed in the river, only two Pseudobarbus afer were sampled from one survey site. The low abundance and narrow distribution of this endangered species is of concern and human-mediated impacts on this species require urgent evaluation and mitigation. Keywords : Baakens River, migration barrier, weir, alien fish, endangered fish
2 citations
TL;DR: It is suggested that these species occupy non-equivalent feeding niches in Cape Fold Ecoregion headwater streams, and that diet partitioning might facilitate their coexistence in these systems.
Abstract: The partitioning of limited resources commonly explains how different species can coexist within the same ecological community. In this 2010 study, the diets of three coexisting freshwater fishes (Cape galaxias Galaxias zebratus, n = 27; Cape kurper Sandelia capensis, n = 60; Breede River redfin Pseudobarbus burchelli, n = 77) were characterised and compared in three headwater streams in South Africa's Cape Fold Ecoregion using gut contents and stable isotope analyses. These data were analysed to ascertain whether the three species exploit distinct trophic niches. Both approaches provided evidence that these species occupy different trophic niches, though with some overlap. However, dietary differences among sites were not consistent and were probably influenced by site-specific factors like resource availability. Pseudobarbus burchelli had a broader niche breadth at Tierkloof Stream than the other two species, but not at Waaihoek or Tierstel Streams. Our results also suggest that P. burchelli consumed a ...
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Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 1 |
| 2018 | 1 |
| 2015 | 1 |
| 2012 | 1 |