Planktons and Biodiversity

Oceans are some people’s lifelong aspiration and marine organisms are one of the most intriguing beings on the planet. It is evident from the theory of evolution that we are also evolved from water beings to the most intellectual species of this planet i.e. earth (in case you are reading from the space station or any other planet). Do you know what makes the oceans more interesting? Well, don’t stress out. It is planktons. These are a wide variety of organisms that are found in water that are too small to move against the fluid current. Along with this, the biodiversity of all these planktons does harm our past, present and future. Even little change in their abundance could lead to apocalypse level changes (at least for some species). Elizabeth Kolbert, a prominent biologist has covered all aspects of these changes in her book “The Sixth Extinction”. Their foremost role is to provide a food source to the small and large aquatic animals.

Aside from representing the bottom few levels of a food chain that supports commercially important fisheries, plankton ecosystems play a role in the biogeochemical cycles of many important chemical elements, including the ocean’s carbon cycle.

Introduction to Planktons


These marine planktons consist of bacteria, archaea, algae, protozoa, etc.

A lot of people believe that planktonic species are minute and microscopic but this is not true. Planktons can be categorized in large organisms like jellyfish too.

Their classification is according to their ecological niche and level of motility. This does not involve the beings that can are present at the surface of the water (plutons) or the ones who can swim actively in the water (nektons such as fish, squid and marine mammals).

The abundance and distribution of plankton depend on nutrients available in the water, the state of water and relativity between large amounts of other plankton.

There is a chemical that is considered as the marker for the distribution and abundance of planktons which is called Chlorophyll.

Distribution and Factors that affect Planktons’ biodiversity

Distribution of planktons

Apart from aeroplanktons, other planktons inhabit oceans, seas, lakes and ponds. The factors that affect abundance vary horizontally, vertically and seasonally. Light in the water body is also an important factor for this variation and availability of these species. Most of the plankton ecosystems are driven by the power of solar energy which confines their primary production to the surface of the water, to geographical regions and seasons having abundant light.

As I said above, a secondary variable is a nutrient availability. These two factors have to be in a fair amount. Even though large areas of the tropical and sub-tropical oceans do have abundant light, they contain relatively low primary production because they have limited nutrients such as nitrate, phosphate and silicate to offer for the process. This is the result of large-scale ocean circulation and water column stratification which dilutes the number of nutrients available. Due to these factors, such regions have primary production at a greater depth and minimal amounts because of reduced exposure to light.

These planktons live throughout the water column. In deeper oceans, zooplankton and bacterioplankton consume organic material sinking from more productive surface waters above. This flux of sinking material, so-called marine snow, can be especially high following the termination of spring blooms.

The local distribution of plankton can be affected by wind-driven Langmuir circulation and the biological effects of this physical process.

Planktonic communities are highly dynamic with assemblages changing rapidly in response to circulation and fertilization patterns and other physical and environmental forcings. This is even more evident in coastal upwelling systems where planktonic assemblages might fluctuate at short-time scales with different assemblages characterizing the various phases of an upwelling cycle. (Marañón, 2015)

Factors Affecting Biodiversity of the Globe

Carbon cycle

Zooplanktons provide carbon to the planktic (adjective of planktons) food web by producing metabolism by respiration or by biomass generation. Organic material gets transported into open waters carbon along with it by the virtue of being dense. This process is called biological pumping. It has been observed that phytoplankton in Antarctica is getting less effective in biological pumping due to seawater acidification which affects the biodiversity of the whole globe.

Oxygen production

The phytoplanktons also do photosynthesis. Here’s something to throw you off your feet: It is estimated that about 50% of the world’s oxygen is produced via phytoplankton photosynthesis.

The absorption efficiency (AE) of plankton is the proportion of food absorbed by the plankton that determines how available the consumed organic materials are in meeting the required physiological demands. Physical factors such as oxygen availability, pH, and light conditions may affect overall oxygen consumption and how much carbon is lost from zooplankton in the form of respired CO2.

Biomass variability

Environmental variability at multiple scales influences the nutrient and light available for phytoplankton, and as these organisms form the base of the marine food web, this variability in phytoplankton growth influences higher trophic levels, influencing populations of zooplankton, fishes, sea birds, and marine mammals.


Species composition plays a key role in ecosystem functioning. Theoretical, experimental and field studies show positive effects of biodiversity on ecosystem processes. These relationships have been hardly studied in planktonic communities of coastal upwelling systems.

The effects of anthropogenic warming on the global population of phytoplankton is an area of active research. Changes in the vertical stratification of the water column, the rate of temperature-dependent biological reactions, and the atmospheric supply of nutrients are expected to have important impacts on future phytoplankton productivity. This small change in this significant organism can lead to huge changes to our normal lives. Hence, it is necessary to study this avenue.


Morán, X. A., López-Urrutia, Á., Calvo-Díaz, A., and Li, W. K. W. (2010). The increasing importance of small phytoplankton in a warmer ocean. Glob. Chan. Biol. 16, 1137–1144. doi: 10.1111/j.1365-2486.2009.01960.x

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