16. Physical features of the site: Describe, as appropriate, the geology, geomorphology; origins - natural or artificial; hydrology; soil type; water quality; waterdepth, water permanence; fluctuations in water level; tidal variations; downstream area; general climate, etc. The caldera, which forms the lake basin, is a remnant of an explosive volcanic crater, whichwas formed approximately 1.000.000 years ago. With a surface area of 415 ha and a depth of 111 m, it is the largest, and the deepest crater-lake in Cameroon. To the north, east and south,the lake basin is surrounded by a steep crater wall, which summits at more than 400 m above sea level. To the west, the catchment includes - in contrast to many other crater lakes - a smallinlet system of streams, which is located in a shallow and boxed-in crater. The inlet-system(Sofo, and its tributary Toh Mbok) is located within the secondary crater and covers an area ofapproximately 8 km2of flat terrain. It has produced a small sediment cone at the junctions with the lake, where the lakes shore is comparatively shallow. The shores descend sharply,spilling into the central plateau of the lake bottom giving the lake a saucer-shaped silhouette.After the formation of the maar, it is believed that the maximum depth of the lake was around400 m before it was filled with sediments from the lake. At the north-eastern shore, a recentlava flow crops out of the bottom of the inner wall with a submerged distal arm. The single outlet, Kaké, flows through a deep gorge in the crater rim located in the south-eastern corner of the lake. Since the gorge is according to estimates recent, it is hypothesised that the lakeformerly drained through the Sofo to the River Mémé system, and not to the River Mungosystem as is the case today.Several sediment cores have been taken from the lake bottom in order to investigate the recent(25.000 years) history of the lake by means of radio-carbon dating and pollen-analysis. The results indicate that the lake’s environs were partly densely forested during its Quaternaryage. Then, about 20.000 years ago, a major disturbance in the lake occasioned the inversion of the upper sediment layers. However, pollen from aquatic plants is present in sediment cores and it is estimated to have been there 20.000 years ago, indicating that conditions favouring aquatic life have always been present.
The water of Barombi Mbo emanates solely from rainwater falling within the confines of thesmall inlet-drainage system in the inner crater wall and the lake surface. The lake level fluctuates by approximately 1 m through the seasons, as there is very little water flowing in one of the streams of the inlet system, Toh Mbok, during the dry season with almost norainfall from December to February. However, there is abundant water during the rainyseason peaking around August and September.The lake is comparatively poor in nutrients (oligotrophic), but nutrient content is increasingslightly with increasing depth. At the surface the mineral content measured in Mikrosiemensis 46, while this value increases to 110 in deeper layers. Additionally, there is a slight increase in dissolved solids in the dry season. The water is near neutral to slightly alkaline at the surface (pH 7.14 to 7.52) and becomes slightly alcalic at greater depths (pH 6.42 to 6.6 at 100m depth). Typical of deep, stratified lakes, the deep waters are devoid of oxygen (nodetectable oxygen below 40 m) and a drastic decrease of 20 to 40 m depths. Although the lakeis normally considered to be oligotrophic with a Secchi-depth (transparency) of up to 11 m,periodic and infrequent events cause a massive decrease of transparency and increase inturbidity, which may result in transparencies below 1 m and a change of the water colour from turquoise-blue to brown. The death of large quantities of fish, especially those from the deeper water layers, during the rainy season of 2001 is the cause of the decrease intransparency and increase in turbidity. During this period, all fish (except perhaps Koniadikume and Clarias maclareni) move into the upper water layers. The Barombi people haverecorded this event for centuries, and it is known in the Barombi language as the Nkum. The people have recorded this event to occur between every seven to fifteen years. The exactcauses are unknown; however, they seem to occur mainly in years with a very heavy rainyseason. The climate of the site is of equatorial type with a long rainy season (March to November)and a short dry season (December to February). The mean annual temperature approximates18° C or even less as the altitude increases. The annual humidity ranges from 70-84 %. The precipitations range from 1,825 mm to 3,000mm.The site consists of three successive volcanic series: a basaltic “lower black series” of tertiary age, a trachy-phonolitic “medium white series”, probably of Neogene age and a basaltic “upper black series” of quaternary age to very recent age.
dogofwar wrote:Wow - killer male pindus! Never seen such behavior from mine - either in a 40g breeder or in the big community. By their size you can see that I've had them for some time...
I've found the Stomatepia mariae to be more aggressive but nothing on the lines of Malawai haps or mbuna. More like Saratherodon mossambicus or other tilapia. More horny than mean or hyper-territorial.
I've heard of a few crashes of pindu tanks from dirty water or dead fish. They like clean water. Sadly a guy in my area imported about 50 of them and had them quarantining in a tank...probably a couple died...and he lost them all.
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