Zambezi River Demersal Habitat
This taxon is one of a number of demersal species in the Zambezi River system of southern Africa. Demersal river fish are found at the river bottom, feeding on benthos and zooplankton
Nutrient levels in the Zambezi River are relatively low, especially in the upper Zambezi; in that reach, above Victoria Falls, most of the catchment drains Kalahari sands, whose nutrient levels are inherently low due to their aeolian formation; moreover, agricultural fertilizer addition throughout the Zambezi watershed is low, due to the shortage of capital available to farmers of this region.
Nitrate levels (as nitrogen) in the upper Zambezi are typically in the range of .01 to .03 milligrams per liter. Correspondingly electrical conductivity of the upper Zambezi is on the order of 75 micro-S per centimeter, due to the paucity of ion content. From the Luangwa River downstream nitrate levels elevate to .10 to .18 milligrams per liter, and electrical conductivity rises to a range of two to four times the upper Zambezi levels. Not surprisingly, pH, calcium ion concentration, bicarbonate and electrical conductivity are all higher in portions of the catchment where limestone soils predominate compared to granite.
There are a total of 190 fish species present in the Zambezi River, including eel and shark taxa. The largest native demersal species present are the 117 centimeter (cm) long tiger fish (Hydrocynus vittatus), the 175 cm African mottled eel (Anguilla bengalensis labiata), the 120 cm Indonesian shortfin eel (Anguilla bicolor bicolor), the 200 cm Giant mottled eel (Anguilla marmorata), the 150 cm African longfin eel (Anguilla mossambica), the 183 cm Sampa (Heterobranchus longifilis), the 150 cm Cornish jack (Mormyrops anguilloides) and the 700 cm largetooth sawfish (Pristis microdon).
Water temperature and chemistry ranges based on 1 sample.
Depth range (m): 85 - 126
Temperature range (°C): 13.678 - 13.678
Nitrate (umol/L): 9.812 - 9.812
Salinity (PPS): 35.148 - 35.148
Oxygen (ml/l): 4.517 - 4.517
Phosphate (umol/l): 1.020 - 1.020
Silicate (umol/l): 8.803 - 8.803
Depth range (m): 85 - 126
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
Recorded at 10 meters.
Habitat: demersal. Inhabits sandy or muddy bottoms of shallow coastal waters, estuaries, river mouths and freshwater rivers and lakes. Usually found in turbid channels of large rivers over soft mud bottoms (Ref. 2847). Feeds on benthic animals and small schooling species. The saw is used for grubbing and attacking prey as well as for defence. Ovoviviparous, producing 15-20 embryos. The saws sell as tourist souvenirs (Ref. 7248). Marketed salted.
Life History and Behavior
Molecular Biology and Genetics
Statistics of barcoding coverage: Pristis microdon
Public Records: 0
Specimens with Barcodes: 3
Species With Barcodes: 1
Relevance to Humans and Ecosystems
The largetooth sawfish (Pristis microdon), also known as the Leichhardt's sawfish or freshwater sawfish, is a sawfish of the family Pristidae, found in shallow Indo-West Pacific oceans between latitudes 11° N and 39° S. As its relatives, it also enters freshwater. This critically endangered species reaches a length of up to 7 metres (23 ft). Reproduction is ovoviviparous. Recent evidence strongly suggests P. microdon is synonymous with P. pristis.
Considerable taxonomic confusion has surrounded this species. It is part of the Pristis pristis species complex, which also includes P. perotteti. P. microdon has sometimes been considered synonymous with P. perotteti, and uncertainty exists over what species the scientific name P. microdon really belong to (the original description lacked a type locality).
Recent evidence strongly suggests the three are conspecific (in which case P. microdon and P. perotteti are synonyms of P. pristis), as morphological and genetic differences are lacking. Three main clades based on NADH-2 genes were evident (Atlantic, Indo-West Pacific, and East Pacific), but these do not match the distributions claimed for P. pristis (circumtropical), P. microdon (Indo-West Pacific) and P. perotteti (Atlantic and East Pacific) respectively.
The largetooth sawfish is a heavy-bodied sawfish with a short massive saw which is broad-based, strongly tapering and with 14 to 22 very large teeth on each side - the space between the last two saw-teeth on the sides are less than twice the space between the first two teeth. The pectoral fins are high and angular, the first dorsal fin being mostly in front of the pelvic fins, and the caudal fin has a pronounced lower lobe.
- Faria, V. V.; McDavitt, M. T.; Charvet, P.; Wiley, T. R.; Simpfendorfer, C. A.; Naylor, G. J. P. (2013). Species delineation and global population structure of Critically Endangered sawfishes (Pristidae). Zoological Journal of the Linnean Society 167: 136–164. doi:10.1111/j.1096-3642.2012.00872.x Retrieved 26 August 2013.
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