Planktons

Planktons, commonly written as plankton, are microscopic and free-floating organisms that form the base of aquatic food webs. They inhabit both marine and freshwater environments and are found near the surface to the deep ocean, in rivers, lakes, and estuaries. The term groups a wide range of species, from single-celled algae to complex multicellular organisms such as jellyfish larvae.

Planktons are divided into two broad categories. Phytoplankton are photosynthetic and include diatoms, dinoflagellates, and green algae. They produce oxygen and serve as the primary producers, capturing sunlight and converting it into organic matter. Zooplankton consist of small animals such as copepods, krill, and larval stages of fish and mollusks. They feed on phytoplankton or other zooplankton and, in turn, are prey for larger predators such as fish, whales, and seabirds.

The abundance and diversity of plankton influence water quality, nutrient cycling, and global climate. Phytoplankton draw down significant amounts of carbon dioxide, playing a key role in carbon sequestration. Periodic blooms can create hypoxic zones, affecting fish populations, while harmful algal blooms may produce toxins that threaten marine life and human health. Because they are highly sensitive indicators of environmental change, plankton research contributes to understanding climate change, ocean acidification, and ecosystem health.