Biology and geology in diving in Nosy Be
Bio - diving in Nosy Be
Several ways to use biological knowledge in diving :
- learn how to avoid some dangers (hydroids, some shells, some equinoderms, some corals, and others venimous animals)
- learn where to find animals to be able to observe it . A lot of animals are living in a very precise biotope. depth, environment (corals, sea weed, sand, sponges), current conditions... all this is very important to define the kind of animal you can discover. particularly for small animals, like seahorses, nudibranchs, frog fish, ghost pipe fish...
- surveying and classifying. as there's a few surveys in madagascar, we're listing the nudibranches and flat worms for several international scientific institutes, because the knowledge evolution of thoses animals is very fast.
- reporting the "Bleaching alerts" (alerts of coral bleaching due to high temperature of water : march-april) emited by the CORDIO (scientific institute monitoring the coral reef evolution in the indian ocean) we are estimating percentages of dead corals or temporary bleached.
- learn how to have a responsible behaviour. for the conservation of the reefs, do not touch animals (touching a turtle or a shark is usually leading to its death, because parasites will fix where the hand removed his protecting mucus), have a good buoyancy to avoid kicking corals or spreading sand on them, don't eat animals which are protected or temporary forbiden to fish (lobster, crab, shrimp..)
- learn how to see the reef biodiversity. Diving to see big stuff, it's interesting.. when there is big stuff, and when it's deciding to come and see you. otherwise, the reef has lots of little animals with different colors, differents shapes, everyday available.
geological context of Nosy Be
The position Nosy Be is really particular, between Madagascar and Africa, which makes a various geology. There's an Influence from the main land (Madagascar), streched by separation of the Gondwana and the Mozambique canal ouverture. Nosy be has been created by several volcanic episodes, ancient to recent. The island has sedimentary limestone and sandstone from lias, with some plutonic intrusions presenting different grades of erosion.
Sea level had big variations. during the different glaciations of tertiary and quaternary, the sea level could be 42m lower which can explain why there's some caves and faults, and some "paleobeaches"
We have 3 dive spots showing "paleobeaches": at 25/27m, spots which topography (continuation of cape, sandy slope, big blocks of granite polished by breaking waves) are showing a shore from an ancient glaciation, period when the sea level was lower. those granite blocs are now covered by a specific fauna, including massive black corals.