Organisms living in an estuarine habitat are adapted to

Step 1: Analyze the question The question asks what organisms in an estuarine habitat are adapted to.

Step 2: Explain the concept An estuary is the place where a river meets the sea, so fresh water mixes with salt water. The most important feature of this habitat is that salinity keeps changing:

• At high tide, sea water flows in and salinity rises.
• At low tide, or during heavy rain and river flooding, fresh water dominates and salinity drops.

Organisms such as mangrove plants, mudskippers, periwinkles, oysters, and crabs, found in the Lagos Lagoon and the Niger Delta, are adapted to cope with these constant salinity changes. They are called euryhaline organisms ("eury" means wide, "haline" refers to salt).

Step 3: Evaluate each option

• A. Withstand wide fluctuations in temperature: Not the defining feature. Estuarine temperatures vary, but not dramatically, since water buffers temperature changes.
• B. Survive only in water with low salinity: Wrong. Estuarine water is brackish and varies from low to high salinity. "Only" makes this option false.
• C. Withstand wide fluctuations in salinity: Correct. This is the main challenge of the habitat.
• D. Feed only on phytoplankton and dead organic matter: Wrong. Estuaries support many feeding types, including predators like fish and crabs. The word "only" makes it false.

Step 4: Answer

Exam tip: Link estuary → brackish water → changing salinity. Be careful with options that use absolute words like "only", since they are often wrong in biology questions.