Question

it is around 10.5. that is more basic than baking soda and almost as alkaline as ammonia and bleach. this alkalinity is due to high concentrations of a chemical called natron. natron is a combination of sodium carbonate and naturally occurring baking soda. sodium carbonate is the substance that the ancient egyptians used to dry out mummies! contact with the lake water can cause chemical burns to many animals or people. however, as in many harsh natural conditions, life has found a way to exist in lake natron. in fact, the existence of one species explains why the lake is red. salt - loving red algae thrive in the lake. the salty water is not the only reason why this specific type of algae does well; the algae blooms best when the lake temperature reaches 140°f (60°celsius). the hotter lake natron gets, the redder it becomes. a toxic type of bacteria exists in the algae blooms, and for most animals, when they eat it, they become very sick. a species of flamingo has adapted to the unusual lake conditions, too. these smaller flamingos have thick skin on their legs that does not get burned in the waters of lake natron. the flamingos get their pink coloration from eating lots of the red algae. the author includes the first sentence of paragraph 4 to summarize the reasons why lake natron is an unusual body of water transition between descriptions of lake natron and the species that live there complete the discussion about lake natron and begin describing a new topic provide further evidence about why only a few species can live in lake natron

Explanation:

The first - sentence of paragraph 4 ("However, as in many harsh natural conditions, life has found a way to exist in Lake Natron.") transitions from the description of Lake Natron's harsh conditions to the species that live there. It shows a shift from the lake's characteristics to the adaptation of life forms to those conditions.

Answer:

transition between descriptions of Lake Natron and the species that live there