''Macrobrachium vollenhoveni'', the African river prawn, is a species of large, commercially important
prawn
Prawn is a common name for small aquatic crustaceans with an exoskeleton and ten legs (which is a member of the order decapoda), some of which can be eaten.
The term "prawn"Mortenson, Philip B (2010''This is not a weasel: a close look at nature ...
from the family
Palaemonidae
Palaemonidae is a family of shrimp in the order Decapoda. Many species are carnivores that eat small invertebrates, and can be found in any aquatic habitat except the deep sea. One significant genus is '' Macrobrachium'', which contains commer ...
from
West Africa
West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Mau ...
. It is a
catadromous
Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousan ...
species that moves from freshwater to brackish water to spawn returning to freshwater as larvae. Recent research has shown that it could potentially be used as a biological control to reduce the rates of infection people living near rivers where this species occurs with
schistosomiasis
Schistosomiasis, also known as snail fever, bilharzia, and Katayama fever, is a disease caused by parasitic flatworms called schistosomes. The urinary tract or the intestines may be infected. Symptoms include abdominal pain, diarrhea, bloody ...
.
Description
''Macrobrachium vollenhoveni'' is a large prawn which grows up to 189mm, but is more usually 100-150mm in length. It is generally a pale colour without any spots but with a thin dark longitudinal line on the carapace and transverse stripes across the abdomen and a thin line across the rear margin of the carapace. The third
maxillipeds are bright yellow and the fingers of 2nd
cheliped
A chela ()also called a claw, nipper, or pinceris a pincer-like organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through New Latin
New Latin (also called Neo-Latin or Modern Latin) is the revival ...
is dark blue with a yellow patch at the joint with the palm.
Other identification features include the
rostrum being equal to or shorter than the antennal scale; with the dorsal edge being convex over the eye and the tip having a short toothless portion. On the legs the second chelipeds have the Carpus shorter than palm, movable dactyls with a single large tooth at midlength of the dactyl.
[
]
Distribution
''Macrobrachium vollenhoveni'' is endemic to West Africa from Senegal
Senegal,; Wolof: ''Senegaal''; Pulaar: 𞤅𞤫𞤲𞤫𞤺𞤢𞥄𞤤𞤭 (Senegaali); Arabic: السنغال ''As-Sinighal'') officially the Republic of Senegal,; Wolof: ''Réewum Senegaal''; Pulaar : 𞤈𞤫𞤲𞤣𞤢𞥄𞤲𞤣� ...
to Angola
, national_anthem = "Angola Avante"()
, image_map =
, map_caption =
, capital = Luanda
, religion =
, religion_year = 2020
, religion_ref =
, coordina ...
, as well as the islands of Bioko
Bioko (; historically Fernando Po; bvb, Ëtulá Ëria) is an island off the west coast of Africa and the northernmost part of Equatorial Guinea. Its population was 335,048 at the 2015 census and it covers an area of . The island is located of ...
, São Tomé
São Tomé is the capital and largest city of the Central African island country of São Tomé and Príncipe. Its name is Portuguese for " Saint Thomas". Founded in the 15th century, it is one of Africa's oldest colonial cities.
History
Ál ...
and Cape Verde
, national_anthem = ()
, official_languages = Portuguese
, national_languages = Cape Verdean Creole
, capital = Praia
, coordinates =
, largest_city = capital
, demonym ...
.
Biology
''Macrobrachium vollenhoveni'' occurs in fresh and brackish waters, including mangrove creeks and inland rivers except for acidic waters.[ A pre-copulatory form of ritualised behaviour which involves olfactory and tactile cues has been observed, fertilisation involves indirect sperm transfer.][ Mating in the genus '' Macrobrachium'' involves the male depositing spermatophores on the ventral side of the female's thorax, between the pereiopods. The female then releases eggs which pass through the spermatophores and are fertilised.] After mating the females carry the eggs downstream from freshwater to the estuarine areas to spawn as the larvae must develop in saline water.[ As the eggs are unable to hatch at higher salinities the females migrate downstream in the rainy season when salinity in the estuarine areas has been lowered.][ The larvae then move back upstream into freshwater to complete their development.][
''M. vollenhoveni'' is omnivorous and the major part of its diet consists of plant materials, algae, diatoms, protozoa and invertebrates. They are non-selective opportunistic feeders, feeding on plankton, especially ]Chlorophyta
Chlorophyta or Prasinophyta is a taxon of green algae informally called chlorophytes. The name is used in two very different senses, so care is needed to determine the use by a particular author. In older classification systems, it refers to a ...
and Bacillariophyta. It has been described as s detritus feeder with a preference for animal remains and has been observed feeding on tadpole
A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found ...
s and fish fry.
Fisheries and aquaculture
''Macrobrachium vollenhoveni'' is fished for using leaf and brush traps in both freshwater and brackish water environments. It is not the primary target in most fisheries which are usually targeting the related species of ''Macrobrachium felicinum
''Macrobrachium'' is a genus of freshwater prawns or shrimps characterised by the extreme enlargement of the second pair of pereiopods, at least in the male.
Species
It contains these species:
*''Macrobrachium acanthochirus'' F. Villalobos, ...
'' and ''Macrobrachium macrobrachion
''Macrobrachium'' is a genus of freshwater prawns or shrimps characterised by the extreme enlargement of the second pair of pereiopods, at least in the male.
Species
It contains these species:
*''Macrobrachium acanthochirus'' F. Villalobos ...
'', although there are reported to be full-time ''M. vollenhovenii'' fisheries in Lagos
Lagos ( Nigerian English: ; ) is the largest city in Nigeria and the second most populous city in Africa, with a population of 15.4 million as of 2015 within the city proper. Lagos was the national capital of Nigeria until December 1991 f ...
Lagoon, Nigeria
Nigeria ( ), , ig, Naìjíríyà, yo, Nàìjíríà, pcm, Naijá , ff, Naajeeriya, kcg, Naijeriya officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf of G ...
at peak season.[
''Macrobrachium vollenhoveni'' has been assessed as being very suitable for aquaculture in numerous studies as one of the largest species in the genus ''Macrobrachium'', because it tolerates a wide range of environments and is an omnivore. The methods of aquaculture are very similar to those used to farm the cultured species '']Macrobrachium rosenbergii
''Macrobrachium rosenbergii'', also known as the giant river prawn or giant freshwater prawn, is a commercially important species of palaemonid freshwater prawn. It is found throughout the tropical and subtropical areas of the Indo-Pacific re ...
''. Studies have looked at the nutritional value of the prawns and the possible use of the rather unappetising shells as a sustainable source of meal to use as food in aquaculture systems. As at 2017, large scale aquaculture of ''M. vollenhovenii''has not taken off, possibly because the requirement for more saline water for hatching eggs has not been understood.[
]
Use as a biological control for schistosomiasis
''Macrobrachium vollenhoveni'' is an omnivore but larger individuals will prey on freshwater snails, including those species which act as intermediate host
In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include a ...
s to the parasitic
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
flatworms
The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a phylum of relatively simple bilaterian, unsegment ...
of the genus Schistosoma which can infect humans and cause the chronic parasitic infection schistosomiasis
Schistosomiasis, also known as snail fever, bilharzia, and Katayama fever, is a disease caused by parasitic flatworms called schistosomes. The urinary tract or the intestines may be infected. Symptoms include abdominal pain, diarrhea, bloody ...
, also known as bilharzia. On the Senegal River
,french: Fleuve Sénégal)
, name_etymology =
, image = Senegal River Saint Louis.jpg
, image_size =
, image_caption = Fishermen on the bank of the Senegal River estuary at the outskirts of Saint-Louis, Senegal ...
the Diama Dam
The Diama Dam, sometimes referred to as the Maka–Diama Dam, is a gravity dam on the Senegal River, spanning the border of Senegal and Mauritania. It is located next to the town of Diama, Senegal and about north of Saint-Louis, Senegal. The pu ...
was built about 50 km from the mouth of the river and blocked the access of prawns up stream of the dam to the brackish water of the estuary for breeding so these populations of prawns eventually collapsed, this in turn led to a huge increase in the rates of infection with ''Schistosoma'' of people living near the river up stream of the dam. This inferred that the loss of prawn populations may be linked to the huge increases in rates of infection with ''Schistosoma''.[ with infection rates attaining 71.8% in some villages.][
As ''M. rosenbergii'' has been shown to be an effective predator of the snails which act as intermediate hosts to the parasites under laboratory conditions it was thought that the similar ''M.vollenhoveni'' potentially would too, and this was shown to be the case. The larger males were more effective in predating the snails so efforts were focussed on producing single sex generations which could be used to populate rivers. As these were males they would grow faster and larger, they would not tend to migrate downstream and they would stay close to where they were introduced to the river. They could also be corralled into shallow water where the snails were concentrated increasing the effectiveness of their predation.][ The prawns could still be harvested for food as the parasite cannot be passed to humans after being consumed by the prawns.][ The use of prawns shows potential in helping to control infection rates of schistosomiasis in conjunction with drugs and other biological controls such as ]catfish
Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...
and domestic duck
The domestic duck or domestic mallard (''Anas platyrhynchos domesticus'') is a subspecies of mallard that has been domesticated by humans and raised for meat, eggs, and down feathers. A few are also kept for show, as pets, or for their ornament ...
s.[
]
References
{{Taxonbar, from=Q13803710
Palaemonidae
Freshwater crustaceans of Africa
Crustaceans described in 1857