Red List of South African Species

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Endangered (EN)
B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v)
Assessors: Francios Roux Andre Hoffman
Contributors: Roger Bills Johan Engelbrecht
Facilitators: Dewidine Van Der Colff Domitilla Raimondo
Reviewers: Edward Harrison Domitilla Raimondo

Rationale (Changed due to New Information|Knowledge of criteria|Incorrect data used previously)

Kneria sp. nov. 'South Africa' occurs only in the headwaters of a few tributaries of the Crocodile River, Inkomati River system. After the completion of the Kwena Dam (formerly Braam Raubenheimer Dam) in 1984 some of the tributaries and Crocodile River mainstem were inundated where previously Kneria sp. nov. 'South Africa' were recorded (Kleynhans 1982, 1984). Kneria sp. nov. 'South Africa' is severely fragmented with seven subpopulations isolated from each other through the construction of the Kwena Dam and through river regulation. Some subpopulations have gone extinct. This taxon has a highly restricted natural distribution and is severely impacted by alien trout and agriculture. It has an area of occupancy (AOO) of 44 km²  (as calculated using a 2x2 km2 grid) and a extant of occurrence (EOO) of 237 km2. The population is severely fragmented with small isolated subpopulations and ongoing decline within its distribution, habitat quality, number of subpopulations and mature individuals. The taxon is therefore assessed as Endangered under criterion B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v).

Distribution

Kneria sp. nov. 'South Africa' is found in tributaries of the upper Crocodile River (Inkomati River system) as well as the Crocodile River mainstem below the Kwena Dam, near Lydenburg, Mpumalanga, South Africa. Seven subpopulations are known to occur naturally, namely Auxloop, Elandspruit, Wilgekraalspruit, Schoemanskloof River, Doornhoekspruit, Sterkspruit and Junglespruit, within a single sub-quaternary catchment. Another population established in the Weltevredenspruit, a tributary of the Elands River (Inkomati River System) following 300 fish from the Auxloop being translocated to this stream (this translocated subpopulation will not be included in the current assessment as it was established outside the natural range of the species and the reason for introduction is not clear).

Population trend

Trend

This species is relatively abundant in habitats where rivers are still in pristine condition. The number of fish caught per meter stream length in the respective subpopulations varied between 0.21 and 5.18 fish per meter. Population sizes of seven subpopulations were estimated based on surveys from 1984 to 1987, the total varied between 525 and 58296 fish per subpopulation (Kleynhans 1988). The relative density of this species in relation to other associated fish species in this habitat varied between 8.8% and 84.7% (Kleynhans 1988). Based on this species’ conservation importance regular surveys are conducted to determine population status. Present data indicate a continuous decline in the extent of occurrence and population size within five of the seven subpopulations. The number of fish sampled per meter stream length varied between 0.04 and 0.93 fish per meter with a relative density in relation to other associated species of 2.8% to 17% (Roux 2016).

Threats

The survival of some Kneria sp. nov. 'South Africa' subpopulations is in doubt, while others are relatively secure. Habitat degradation from agricultural activities is the main threat to this species. All known localities are on private agricultural land where weir construction, water abstraction, bank erosion through grazing and crop cultivation occurs (Skelton 1987). Furthermore, alien riparian plant invaders wattle (Acacia mearnsii) and poplar (Populus alba) occur along some of the streams, further destabilizing stream banks. In several streams introduced Rainbow Trout (Oncorhynchus mykiss) appear to have restricted or eliminated some subpopulations. After the construction of the Kwena Dam, Largemouth Bass (Micropterus salmoides) established in this impoundment and recently this species has been recorded to move into the lotic systems where Kneria sp. nov. 'South Africa' occur.

Conservation

Kneria sp. nov. 'South Africa' is a listed fish species of conservation concern and is listed on the Mpumalanga Biodiversity Sector Plan (MBSP) and labelled as critically endangered and incorporated into the MBSP as fish support areas (Lötter et al. 2014). However, its distribution range is entirely within privately owned land where the prime land use is agriculture. None of the distribution localities fall within protected areas. Urgent surveys are needed to assess the current status for this species. Areas suitable for conservation actions and possible sanctuary areas need to be identified. Possibly some streams need to have alien species removed to allow recovery or for restocking from adjacent stream subpopulations. As part of this process an assessment of the genetic structuring of Kneria sp. nov. 'South Africa' populations would be desirable. Use of water resources by riparian land users needs to be carefully controlled.

References 

[@electronic{2426,
 address = {www.iucnredlist.org},
 author = {IUCN},
 title = {The IUCN Red List of Threatened Species. Version 2017-3},
 year = {2017}
}
,@article{2566,
 author = {Skelton, P.H.},
 title = {South African Red Data Book - Fishes},
 year = {1987}
}
,@techreport{2572,
 address = {Lydenburg},
 author = {Kleynhans, C.J},
 title = {Die ekologie van skaars en moontlik bedreigde vissoort van Transvaal},
 year = {1982}
}
,@phdthesis{2572,
 author = {Kleynhans, C.J. },
 school = {University of Pretoria},
 title = {Die verspreiding en status van sekere seldsame vissoorte van die Transvaal en die ekologie van sommige spesies.},
 year = {1984}
}
,@article{63389,
 author = {Kleynhans, C.J. },
 journal = {Journal of Limnological Society of Southern Africa },
 number = {2},
 pages = {108--118},
 title = {Aspects of ecology of Kneria auriculata (Pellegrin, 1905) (Pisces:Kneriidae) from the Eastern Transvaal, South Africa},
 volume = {14},
 year = {1988}
}
,@techreport{63389,
 address = {Lydenburg},
 author = {Roux, F. },
 title = {Internal Report: Biomonitoring results and population status of Kneria},
 year = {2016}
}
,@techreport{63389,
 address = {Nelspruit},
 author = {Lötter, M.C., Cadman, M.J. and Lechmere-Oertel, R.G. },
 title = {Mpumalanga Biodiversity Sector Plan Handbook},
 year = {2014}
}
,]
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