Aquarium launches desperate search to save a species down to 2 individuals
May 10, 2013 - Aquarists at ZSL London Zoo have launched a worldwide appeal to find a female mate for a fish species that is believed to have gone extinct in the wild.
The fish, Mangarahara cichlid (Ptychochromis insolitus), was once found in the Mangarahara River in Madagascar, but dams have dried up its habitat. The last two known individuals now reside at ZSL London Zoo’s Aquarium. But both are male.
The zoo is therefore asking any zoos or aquarium keepers who may have females to contact it…
Lake Natron, located in Tanzania, is said by NASA to be the world’s most caustic body of water. Fed by mineral rich hotsprings, constant evaporation concentrates salts, leaving water that has a pH of 9 - 10.5 (almost the pH of household ammonia!).
Despite the hostility of the habitat, the high salt levels and pH are ideal environments for halophiles, microscopic organisms that are adapted to salt. Cyanobacteria and spirulina, which are responsible for the red colour of the lake, photosynthesise and provide energy for more complex organisms to feed on.
The Lake is the only regular breeding place for 2.5 million Lesser Flamingos(Phoenicopterus minor) which feed on the spirulina in the lake. The birds take advantage of the deterrent waters and plentiful amounts of food provided in an otherwise harsh environment.
The Alkaline Tilapia fish (Alcolapia sp.) also live in the waters, inhabiting the niches at the edges of hot spring inlets. They are well adapted to the high temperatures (up to 110°F or 43°C) and pH of the lake. The fish excrete urea, as the usual ammonia is hard to diffuse in the environment. They can also gulp atmospheric air to compensate for the hypoxic waters.
Parallel Evolution: when similar characterisitcs arise in closely related organisms
Most people who have studied even a little evolutionary biology are aware of the marvelous diversity of the Lake Victoria cichlids. These fish have radiated to fill nearly all available niches in the lake. Over only a few million years, 300 species were developed from one ancestral populations.
What you may not know is that there are cichlids in Lake Malawi and Lake Tanganyika, too, and all originated from similar ancestral populations. What’s more, the cichlids in each of the three lakes have evolved to fill nearly the exact same niches. The correspondence in ecology and morphology between the fish of the three lakes is the most spectacular example of parallel evolution that I’ve seen. Take a look at this figure, where the fish on the left come from Lake Tanganyika and the ones on the right are from Lake Malawi.
A few inland lakes in Africa boast a massive diversity of cichlid species. This group of closely related, but distinct, species in an isolated area is known as a species flock. The several hundred cichlid species may have resulted from the many environmental variations of the lake, as ancestors differentiated to exploit different biotic factors.
The brain’s pituitary is the undisputed champion of the endocrine system, credited with exerting more control over the growth of our body than any other structure. But a new contender has stepped into the ring—one that hits below the belt. Scientists have found for the first time that, at least in Mozambique tilapia (Oreochromis mossambicus), the gonads act as a “secondary pituitary,” helping the fish reach their adult size. Without these sex organs—which produce sperm in males and eggs in females—the fish only grew to a fraction of their normal size, the team reports online this week in the Proceedings of the National Academy of Sciences.
Transplanting gonads back into the tilapia—even into nonsense locations such as the fish’s back—allowed the animals to grow again. The findings may apply to all vertebrates, including humans, the team reports. They could also be a boon to fisheries, which struggle to keep fish from breeding before they have reached the size at which they can be killed for food.
Your fish are probably pissed off if you keep them in a small aquarium, suggests a study published this month in the Journal of Applied Animal Welfare Science that looked at levels of aggression in the common aquarium species Midas cichlid (Amphilophus citrinellus). Fish stored in average-sized aquariums used by most small collectors (i.e. tanks holding fewer than 100 gallons) were significantly more aggressive and violent than fish in artificial stream environments or home in their natural habitat. With 180 million or so ornamental fish in America, that’s a lot of mad fish…