Two of the species belonging to the Asatharia genus of freshwater bivalve mollusks found in Africa are currently listed as vulnerable. One of these species is Aspatharia divaricata, which is endemic to Tanzania's Lake Victoria and has been recorded in locations near Lake Victoria's south-eastern end, near the Simin River, and near Buvuma Channel near the northern end.
The other species, Aspatharia subreniformis, is endemic to Malawi's Lake Malawi, where it is predominantly known from an area known as Nkhotakota.
Biology and Ecology
A muscular foot allows freshwater mussels to slowly move through the gravel, silt or sand of their aquatic home. They are protected from predators and against drying out when they venture up on the shore by a close fitting shell.
Glochidia, as the mussel's larvae are known, develop before undergoing the metamorphosis into mussels by attaching themselves as parasites to fishes. This is complicated not only by the fact that the glochidia needs to find a fish in the first place, it then has to be the right species of fish for the successful continuation of the life cycle. Which species of fish represents the main, preferred host is currently unknown.
Adult mussels attach themselves to the river floor and feed on tiny zooplankton, phytoplankton an other organic matter they can filter from the surrounding water through specialised regions within their shells. In essence, the water is taken in and filtered through the gills, where food particles are subsequently trapped and eventually digested.
Reproduction takes place by the male releasing his sperm into the water when the currents are strong enough to carry the sperm to the eggs contained within the shell of the female. Once fertilised, the eggs develop into glochidia inside the female's gills until they are released into the water.
Threats and protective Measures
Found only in the before-mentioned lakes and rivers, Aspatharia mussels are threatened by habitat loss resulting from human activities. As agricultural, residential and industrial activities increase, rivers and lakes suffer pollution, rivers are diverted, dredged or dammed up and so on. This not only affects the Aspatharia species, but their host-fish and their main sources of food.
Unfortunately, exact figures of populations and exact locations are not known or researched, making it difficult to put any kind of protective measures into place. This is a shame, as not only the mussels, but also the predators using them a prey and indeed the rivers themselves will ultimately suffer.
Like all other species on this planet, the Aspatharia mussel species are just one small part of a much larger picture. If this vital component of the overall regional ecology disappears, who knows how many species will ultimately suffer from their demise.
Maybe it is time scientists were given the resources necessary to research these species in greater detail, which may lead to suggestions of how to protect this species from becoming extinct anytime within the near future.
One thing is for sure, humanity will have to consider ways to stop or at least slow down the changes we have forced upon the planet before it is too late for all life.