Lake Tanganyika, shores of Ikola, shallow sediment free rocky habitat, Tanzania

27th place in Biotope Aquarium Design Contest 2019

Turkey. Fatih Özdemir

Volume: 447 L
Dimensions: 125x50x65 cm
List of fishes: Tropheus sp. Ikola
List of plants:
Description of decorations: 1- 40 kg of nautral dark coloured river sand (collected from river, in same look and structure with sand in Ikola Shores)
2- 120 kg of natural dolamite stones in variable sizes (collected from nature, from football ball’s size to pebbles)
3- Transparent Turquaz Background
Description of equipment: 1- Ligthining: 8x led bulb (12 watt, 6500 K, Dayligth), 2x led fluorescent (24 watt,120 cm,6500 K, Dayligth), 6x Spot led bulb (8 watt, 3000 K), Timer Plug, UV ligthining system attached to filter,
2- Filtering: 3x external filters totally 2500 L/H,
3- Heating: 300 watt heater.
Water parameters: Ph: 8,4-8,6, Temp: 25,6°C, Electirical Conductivity: 650 µS, GH:13, KH:12 in addition Nitrate: 5-15 ppm and Nitrite: 0 ppm
Additional info: Weekly % 20 water change and maintanence. In weekly maintanance, glasses are cleaned and equipment check done. In every 6 mouhts filters media are cleaned but this process is in a weekly row, just one filter in every weekend.


Description of the area surrounding the biotope: Lake Tanganyika (5°30′S 29°30′E) is in the western side of the African Rift system. It is the largest of the African rift lakes by volume and the second deepest lake in the world only exceeded by Lake Baikal.(2) Climate in the lake basin is semihumid tropical. Annual rainfall is roughly 1 m and river inflow could raise the Lake level by 0.5 m per year.(3) The lake occupies a series of interconnected half-graben basins. The lake is currently an open basin, discharging into the Zaire basin via the Lukuga River. Most water loss is from evaporation but the outlet serves primarily to maintain constant lake level.(2) In past Lukuga outlet was used as a kind of a natural valve system whenever the lake level rose beyond a certain point.(3) The lake receives continuous, but seasonally variable, inflow from four major rivers (Malagarasi, Ruzizi, Lugufu, and Lufubu), as well as numerous small rivers. (2) The population density of the Lake Tanganyika basin varies between 13-250 persons/km2. The full drainage basin has a population of greater than 10 million people which is growing at a rate of 2.0-3.2 percent per year. Lake Tanganyika’s fisheries yield 165,000 to 200,000 tons of fish per year, employ around 100,000 people, and provide 25 to 40 percent of the protein needs of around 1 million people.(4) The lake and its Basin provide a diverse range of ecosystem services that sustain the livelihoods of millions of people.(5) This is putting too much pressure on underwater habitat of lake and this means diminishing enviroment. Lake Tanganyika is dividing the floral regions of eastern and western africa, and characteristic of the flora of western Africa oil palms grow along the lake’s shores. Rice and subsistence crops are grown along the shores. Hippopotamuses and crocodiles abound, and the bird life is varied.(9) Basin is renowned for its terrestrial biodiversity and scenic beauty with several forest reserves and national parks. (5) When we come to my specific point Ikola Shore, it s a flat region, at begining of shore area covered with stones and rarely sand which their extension goes under water. Areas after shore is generally covered with residental occupations and partly with bushy forests including small trees and bushes.(*,6) There is no inflow or outflow nearby so this makes region less populated comparing to other regions in terms of land population. (6,*,8)

Description of the underwater landscape of the biotope: In lake Tangayika according to depth and region it has it’s own types of biotopes which are moslty underwater extension of shore part. (12,*) This stituation has caused different evolution of species in lake Tanganyika. Ikola shore shows all evidences of being a tecthtonic lake by it’s chaotic but beatiful stoney and rocky formations. Ikola Shore is a small part in Tanzania, it’s stoney shores goes on with it’s extension to under water and forms a sediment free rocky habitat which is stones on stones, small stones between big stones and towards depths bigger stones on sand. (7,12,*,6) Strong Africa sun shine with help of low depth lets algea grow fastly and abundant but waves don’t let sediment to accumulate. Due to fluctilating water level according to seasons while some stones are fully covered with algea firm in parts which is always under water, somes are with less algea in upper parts. Bottom are covered with mixed fine sand and it starts to be seen in bottom when going down towards depths. As a sediment free rocky habitat in 0-5 meters depth it’s pefect for species with lots of algea to eat and lots of shelters to hide from predators When we gether all information about habitat and study on forms and behaviours of species living in this habitat we can surely see how species evolved in body forms and behaviours according to habitat. So they have stripped body for having camoflage to imitate reflecting sunshine on stones, big fins to swim in strong waves and never coming up surface to get feed due to danger mostly from birds. Waves get stronger because of low depth and stir up bottoms much so this makes water some blurry but very oxygen rich and clean. Bottom has dark coloured mixed fine sand. In starts of shore bottom type is stones on stones but when going deeper sand can be seen and stones gets bigger.(*,8-10) Stone sizes are variable from pepples to huge rocks.

Description of the parameters of the habitat: Most of the influent streams originate on rift escarpments, close to the lake, and therefore carry very low dissolved solid loads. But the Ruzizi River drains alkaline from Lake Kivu to the north, and is the dominant source for most solutes excluding lake Tanganyika.(2) Lake Kivu is responsible for Ruzizi river unsually high Mg/Ca water in the enter of Lake Tanganyika but it s deluted by other streams so a lower salinity and a lower alkalinity water are produced. Ground water from small springs has been noticed but it’s effect on lake’s water is relativly small.(2) Surface water of Lake Tanganyika is very well saturated with oxygen but it’s rapid decline can be regocnized easliy when going down to depths as oxygen dissapears H2S becomes abundant which makes habitat inhabitable for plankton and fish life.(3) Lake’s water temparture changes according to depth and season.(2) But lake’s water is getting warmer since the 1800s and thanks to global warming this process has accelerated since the 1950s. (1)
Tempeture: Changing according to seasons (wet season/dry season) between 24-28°C, but at depths greater then 400 meters is more stable between 23,1-23,4°C, (1)
Ph: Around 9 at depths of 0-100 meters, 8,7 below this and 8,3 at deepest parts, (1)
Electirical Conductivity: Upper parts 670 and deepest parts 690, (1)
Other Parameters: GH 12-20, and the KH 10-15.

List of fishes and invertebrates occurring in the nature biotope: If we accept region as Mkanzi,
Altolamprologus fasciatus, Aulonocranus dewindti, Cyathopharynx foae, Eretmodus marksmithi , ExLamprologus brevis, ExLamprologus ocellatus, ExLamprologus ornatipinnis, Lepidiolamprologus attenuatus, Lepidiolamprologus elongatus, Lestradea perspicax, Limnochromis auritus, Neolamprologus furcifer, Neolamprologus modestus, Neolamprologus savoryi, Neolamprologus sexfasciatus, Neolamprologus tetracanthus, Ophthalmotilapia nasuta, Ophthalmotilapia ventralis ,Paleolamprologus toae, Petrochromis ephippium, Petrochromis famula, Petrochromis fasciolatus ,Petrochromis polyodon, Petrochromis sp. ‘orthognathus ikola’ ,Pseudosimochromis babaulti ,Spathodus erythrodon, Telmatochromis temporalis, Telmatochromis vittatus, Tropheus annectens ,Tropheus sp. ‘ikola’ , Xenotilapia boulengeri.Variable invertabres(11)

List of plants found in the nature biotope:

Threats to the ecology: One of threats Lake Tanganyika faces is overpopulation of lake shores in purpose of tourism, agriculture and fisheries. Overpopulation around lake means more human around and human means pollution with extraordinary use of natural resources. Rising urbanization rate around lake brings lots of problems for underwater. All debris from residental areas goes in to lake and drops water quality and when we remember that main water loss from evaporation. This stituation can turn lake in to a big trash can fastly and we all can quess end of this story. Maybe our childeren will have no Lake Tanganyika to inspire and recreate. Solution to this problem is simple planned urbanization with advanced underground systems, control of using resources and respect to nature. This is not just a problem of countries around lake it’s problem of all world because Lake Tanganyika is one of the treasures of world. So actions must be done immediately by whole world. (13,14,15,*)

Sources of information:

*- My conclusions from resources, videos and maps.
2- (pg. 444)
3- (pg.230)
8- (Between 4:00 min and 6:15 min)

Comments of the members of the jury of Biotope Aquarium Design Contest 2019