Lake Ejagham
Encyclopedia
Lake Ejagham is a small lake near Eyumodjock
in the Southwest Region of Cameroon
. Unlike many other lakes in the region, it is not a volcanic lake, but is likely a solution basin formed by groundwater
during the last Ice Age. This highly isolated lake is roughly oval
in shape, lacks an inflow, but has an outflow into the Munaya River (part of the Cross River
system). The outflow is impassable to most fishes because of a waterfall.
Despite its very small size, it supports 7 endemic species of tilapiine cichlid
fishes (Tilapia deckerti
, T. ejagham
, T. fusiforme
, T. nigrans
, Sarotherodon lamprechti
, and S. knauerae
). Of these, 6 were only scientifically described
in 2010 and 2011, and have therefore not been rated by the IUCN, but they likely face the same threats as T. deckerti (the single older species that has been rated by the IUCN). T. deckerti is considered critically endangered
due to pollution
and sedimentation
from human activities, and could also be threatened by large emissions of carbon dioxide
(CO2) from the lake's bottom (compare Lake Nyos
). A species of catfish from the genus Parauchenoglanis
has been introduced
to the lake, and this probably presents a serious threat to the endemic cichlids.
Eyumodjock
Eyumodjock is a town and commune in Cameroon, and the sub-divisional headquarters of the Eyumjock sub-division in the Manyu division. The small Lake Ejagham is near the town.-References:*...
in the Southwest Region of Cameroon
Cameroon
Cameroon, officially the Republic of Cameroon , is a country in west Central Africa. It is bordered by Nigeria to the west; Chad to the northeast; the Central African Republic to the east; and Equatorial Guinea, Gabon, and the Republic of the Congo to the south. Cameroon's coastline lies on the...
. Unlike many other lakes in the region, it is not a volcanic lake, but is likely a solution basin formed by groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
during the last Ice Age. This highly isolated lake is roughly oval
Oval
An oval is any curve resembling an egg or an ellipse, such as a Cassini oval. The term does not have a precise mathematical definition except in one area oval , but it may also refer to:* A sporting arena of oval shape** a cricket field...
in shape, lacks an inflow, but has an outflow into the Munaya River (part of the Cross River
Cross River (Nigeria)
Cross River is the main river in southeastern Nigeria and gives its name to Cross River State.It originates in Cameroon, where it takes the name of the Manyu River....
system). The outflow is impassable to most fishes because of a waterfall.
Despite its very small size, it supports 7 endemic species of tilapiine cichlid
Tilapiine cichlid
The Tilapiini is a tribe within the family Cichlidae commonly known as tilapiine cichlids. Most of the taxa herein are called "tilapias", a diverse and economically important group containing the genera Oreochromis, Sarotherodon and Tilapia. A number of smaller genera, such as Alcolapia, Danakilia,...
fishes (Tilapia deckerti
Tilapia deckerti
Tilapia deckerti is a critically endangered species of fish in the cichlid family. It is endemic to Lake Ejagham in western Cameroon. It is threatened by pollution and sedimentation from human activities, and potentially also by large emissions of carbon dioxide from the lake's bottom...
, T. ejagham
Tilapia ejagham
Tilapia ejagham is a species of fish in the cichlid family. It is endemic to Lake Ejagham in western Cameroon. It was only scientifically described in 2010 and has therefore not been rated by the IUCN, but it likely faces the same risks as the critically endangered T...
, T. fusiforme
Tilapia fusiforme
Tilapia fusiforme is a species of fish in the cichlid family. It is endemic to Lake Ejagham in western Cameroon. It was only scientifically described in 2010 and has therefore not been rated by the IUCN, but it likely faces the same risks as the critically endangered T...
, T. nigrans
Tilapia nigrans
Tilapia nigrans is a species of fish in the cichlid family. It is endemic to Lake Ejagham in western Cameroon. It was only scientifically described in 2010 and has therefore not been rated by the IUCN, but it likely faces the same risks as the critically endangered T...
, Sarotherodon lamprechti
Sarotherodon lamprechti
Sarotherodon lamprechti is a species of fish in the cichlid family. It is endemic to Lake Ejagham in western Cameroon. It was only scientifically described in 2011 and has therefore not been rated by the IUCN, but it likely faces the same risks as the critically endangered Tilapia deckerti, which...
, and S. knauerae
Sarotherodon knauerae
Sarotherodon knauerae is a species of fish in the cichlid family. It is endemic to Lake Ejagham in western Cameroon. It was only scientifically described in 2011 and has therefore not been rated by the IUCN, but it likely faces the same risks as the critically endangered Tilapia deckerti, which is...
). Of these, 6 were only scientifically described
Binomial nomenclature
Binomial nomenclature is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages...
in 2010 and 2011, and have therefore not been rated by the IUCN, but they likely face the same threats as T. deckerti (the single older species that has been rated by the IUCN). T. deckerti is considered critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
due to pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
and sedimentation
Siltation
Siltation is the pollution of water by fine particulate terrestrial clastic material, with a particle size dominated by silt or clay. It refers both to the increased concentration of suspended sediments, and to the increased accumulation of fine sediments on bottoms where they are undesirable...
from human activities, and could also be threatened by large emissions of carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
(CO2) from the lake's bottom (compare Lake Nyos
Lake Nyos
Lake Nyos is a crater lake in the Northwest Region of Cameroon, located about northwest of Yaoundé. Nyos is a deep lake high on the flank of an inactive volcano in the Oku volcanic plain along the Cameroon line of volcanic activity...
). A species of catfish from the genus Parauchenoglanis
Parauchenoglanis
Parauchenoglanis is a genus of catfishes of the family Claroteidae.The range of the genus Parauchenoglanis stretches from the coastal lowlands of Benin and Nigeria to the Okavango and upper Zambezi River systems in Botswana and Zambia.-Species:Parauchenoglanis contains the following nine...
has been introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
to the lake, and this probably presents a serious threat to the endemic cichlids.