Question

Estuaries are highly productive as they are nutrient trap due to the mixing of
(a) Ocean and pond
(b) Lake and river
(c) Pond and lake
(d) River and seawater

Answer 1

Due to the mixing of a natural flowing watercourse, typically freshwater, and the saline content of water, estuaries are highly active as they are nutrient traps. The tidal mouth of this inland watercourse is an estuary.

Complete step by step answer:
Estuaries are fragile bodies of water where the river's freshwater and the sea water's salty water meet and mix. They are in charge of transporting the nutrients and combining them. The difference in river water and sea-water sedimentation, wind movement, and tidal activity allow the nutrients to be trapped and transported. The estuaries are covered from the influences of the ocean by reefs, deltas, and barrier islands.
So, the correct answer is, ‘River and seawater’.

Additional information: An estuary is the tidal mouth of a coastal bay or river where there is a combination of fresh and seawater. Turbulence allows an estuary to be extremely active. Fluctuations of temperature and salinity are present. Phytoplanktons (blue-green algae, green algae, diatoms, dinoflagellates) , zooplankton (protozoa, crustaceans, rotifers) , Necton (fish and some crustaceans) , and Benthon (algae attached, snails, clams, prawns, etc.) are the dominant life forms.
An estuary is a partially enclosed water body formed when the land's fresh water meets and mixes with the ocean's saltwater. Due to rapid nutrient circulation and rapid removal of waste products, it is also one of the most active ecosystems. Bays, lagoons, harbors, inlets, sounds, ponds, and swamps may also be called estuaries of various sizes.

Note: Sediments and contaminants from rivers and streams are washed out by estuaries until they flow into the ocean, supplying humans and marine life with cleaner water. However, coastal development, the introduction of invasive species, dams, global climate change, and overfishing have led to a decrease in the health of estuaries.