WHAT IS THE PLANKTON

Plankton is a collective name that encompasses a group of organisms that live in both seawater and freshwater and that are too small or too weak to be able to swim against the current. Within what we call plankton we include organisms such as bacteria, some types of algae, crustaceans or molluscs.

Therefore, plankton are organisms that are dragged adrift by tides and currents and that live in the pelagic zone, that is, they live in the middle and upper areas of the oceans' waters, they are also present in rivers or lakes Some of these organisms can be seen with the naked eye but to see most of the microorganisms that make up the plankton we will need the help of a microscope.

Source, Wikimedia

Characteristics

Most species are transparent with a certain iridescence, and present colors only under a microscope. The superficial species are bluish, and the other reddish ones. Some emit luminescence, like the noctiluca. Most species of plankton measure less than a millimeter, others, on the other hand, are larger, such as siphonophores, ctenophores and jellyfish.

Types of plankton

Among the types of plankton are the phytoplankton or plant plankton that is formed by organisms that carry out photosynthesis and the zooplankton that is the animal plankton.

Phytoplankton or plant plankton

To develop phytoplankton from living in places where there is light and minerals in suspension. For this reason, phytoplankton can only develop in the first layers of water, since the light that crosses this depth does not have enough quality to adequately produce photosynthesis. The depth to which the phytoplankton is located depends on the density, the salinity and the water temperature. The lower amount of minerals in suspension far from the coast also determines their development. The plankton that is far from the coast is known as oceanic plankton and has a lower quantity and quality than the plankton that lives on the continental shelf, called neritic plankton.

Phytoplankton usually have a higher quality and abundance in spring. Its quality is lower at the time it has exhausted mineral resources, something that usually happens during the summer. When the autumn arrives, the bacteria re-mineralize phosphorus and nitrogen so that the planktonic plant organisms have resources again and resurface again.

Among the organisms that make up phytoplankton we have the cyanobacteria, a type of plant microorganism, and the algae (green algae, golden algae, bluish green algae and diatoms). Phytoplankton is crucial for marine life because it forms the basis of trophic chains. It must also be borne in mind that most of the oxygen existing in the Biosphere is due to plant plankton. It is considered that 90% of the oxygen in the atmosphere is produced by phytoplankton.

Source, Public Domain

Zooplankton or animal plankton

The zooplankton constitutes the animal plankton. It is constituted by those organisms that feed on phytoplankton, therefore they are the primary consumers in the food chain of the aquatic ecosystem. Among the main components of zooplankton are copepods, a type of very tiny crustaceans that make up almost 2/3 parts. Other organisms that are part of this type of plankton are protozoa (especially dinoflagellates and foraminifera), many very young fish, eggs and larvae of fish and other small aquatic animals such as worms, mollusks and echinoderms. Small fish are fed from zooplankton and these feed as food for other larger fish and so on until they reach the end of the food chain formed by large aquatic predators: large fish, such as sharks, tuna, etc. or the large marine carnivorous mammals, among which are dolphins, killer whales, sperm whales, beluga, porpoises or narwhals. Killer whales are sometimes predators of the cetaceans themselves.

Copepod. Wikimedia, Public Domain

Importance of plankton

Since the plankton community is made up of most of the organisms present in the pelagic ecosystem and contains a relevant proportion of the primary producers and secondary and tertiary producers, it constitutes the largest available biomass where the trophic plot begins in aquatic environments It provides food to living beings ranging from microscopic size to large ocean animals such as whales, which weigh tons of plankton feeding as the main diet for their survival. The plankton carries out the greatest mobilization of biomass of the planet daily in its daily vertical migration, which in terms of energy and mobilized biomass constitutes what is known as the biological pump that controls a large part of the organic biogeochemistry of the ocean. Phytoplankton contributes about 50% of the planet's primary production. The knowledge of the biogeography diversity, abundance, ecology, physiology and evolution of this community are indicators of the productive potential of the ecosystems that, for the interests of humans, contribute to the biomass available for fisheries. Plankton organisms can be useful indicators of changes in ecosystems due to their rapid response to environmental conditions dictated by their relatively short life cycles and sensitivity to pollution.

In biotechnology, plankton organisms are used for their culture as a source of food in aquariums and for obtaining other food products for the development of fisheries. They are also used in studies of toxicity and obtaining pigments, among many other applications of interest to man. Dead plankton produces a layer of sediment that once fossilized produces the adored oil.

References.

https://en.wikipedia.org/wiki/Plankton

https://www.whoi.edu/science/B/people/kamaral/plankton.html

https://www.britannica.com/science/plankton