Plankton - Nutritional Properties

What is plankton?

General information on plankton

Plancton is the name of a set of very small organisms and microorganisms (floating or sinking) that is at the base of the aquatic food chain (for example tiny fish, manta rays, whale sharks, cetaceans, etc.), plays a primary role in the biogeochemical cycles of many elements (such as oceanic carbon) and produces oxygen (up to 50% of the total on the planet).

Plankton is not a phylogenetic or taxonomic classification, but rather a grouping of different species within the same ecological niche. Among the animal, plant and microscopic organisms of the plankton we mention: viruses, bacteria, fungi, archaea, monocellular and multicellular algae, protozoa, larvae, molluscs, crustaceans and jellyfish.

The trophism of the planktonic (or planktonic) population depends on many environmental factors such as the presence of nutrients, the physical state of the water column, etc.

Generally of bio and ecological marine interest, plankton (or better, a part of it) is also a source of sustenance for some human activities. We are talking about krill and some microalgae.

Let's go into more detail.

Did you know that ...

The name plankton derives from the Greek adjective "planktos", which means wandering (drifting, vagabond, wanderer), and by extension was coined by Victor Hensen in 1887.

The study of plankton is called "planktology" and a planktonic individual is called "plankter".

Krill and Algae

Plankton krill

Krill is a group of creatures, more precisely crustaceans, which are part of the plankton - macroplankton (see below). Fished and used mainly as a feed for fish farms (especially salmon and trout), it is also a substrate for the extraction of fats used as food supplements.

Krill oil is an oil rich in omega 3 fatty acids, in particular:

• Eicosapentaenoic acid - EPA
• Docosahexaenoic acid - DHA.

Plankton algae

In plankton there are various types of algae that make up the so-called phytoplankton. Only one, however, has been assessed as suitable for food consumption: the unicellular Tetraselmis chuii . Rich in nutrition, it is considered the last frontier of functional food-food supplements.

This plankton algae contains mainly EPA and DHA fatty acids, vitamin C, vitamin E and vitamin B12 (cobalamin). Cultivated in aquaculture, it is processed and marketed as a dehydrated powder, sometimes in capsules or tablets.

The distribution companies do not provide particular recommendations on the conservation of the product even if, as we will see in the next paragraph, it could be very useful to follow some tricks.

Plankton Omega 3

Produced in the body from alpha linolenic acid (ALA - typical of plant-based foods such as oilseeds, starchy seed germs, vegetables, fruits, etc.), although they are metabolically more active than their precursor, EPA and DHA are not considered essential.

On the other hand, the metabolic pathway of omega 3 is partially shared by the omega 6 which, being more abundant in the diet, tend to limit the availability of enzymes. For this reason it is advisable to fractionate the food intake of omega 3 by taking not only foods rich in ALA, but also foods with EPA and DHA.

Eicosapentaenoic acid and docosahexaenoic acid perform many beneficial functions; the main ones are:

• Constituents of cellular membrane
• Precursors of anti-inflammatory eicosanoids, which fight metabolic inflammation
• Anti-caking, blood thinning
• They improve the profile of lipemia, especially by decreasing the triglycerides in the blood
• They modulate blood pressure, reducing it if excessive
• Counteract the severe damage of type 2 diabetes mellitus
• At an early age they support eye and brain development
• Preserve brain activity in old age
• They can improve mood by counteracting certain depressive symptoms
• It is hypothesized that tendons, joints and muscles are positively affected by sports inflammatory patterns.

It is however necessary to specify that EPA and DHA, therefore also krill oil and presumably also the powder of planktonic algae, are quite perishable and must not be exposed to: light, heat, oxygen and free radicals. Antioxidant vitamins such as tocopherols (vitamin E) and some retinol equivalents (provitamins A, such as carotenoids, such as beta carotene, astaxanthin, lycopene, etc.) are added for greater conservation. Furthermore, the preservation of krill oil should preferably take place in the refrigerator, in airtight and dark containers, for limited periods of time.

We conclude by emphasizing that plankton oil is qualitatively superior to that of fish (for example, salmon) and fish liver (for example, cod). It is equaled only by the oil of multicellular algae (they are not the same as we talked about above, which instead belong to the group of unicellulars), it has an excellent level of purity and a very low concentration of pollutants (mercury, lead, dioxins, etc.). It is sold mainly in the form of gel capsules.

Other Uses

Role of plankton in fish farming

We have said that krill is widely used as fodder for fish farming, but the importance of plankton in this kind of activity is much wider.

Environmental phytoplankton and zooplankton play a role, now recognized and proven for a long time, in extensive and semi-intensive fish farming. Decades have passed since breeding management strategies have evolved, based on the detection of planctic trophism, demonstrating the enormous importance of this element not only in open waters, but also in man-made artificial environments.

Damaging the marine ecosystem at the base, jeopardizing the planktonic population (for example with pollution, excessive krill, etc.), means causing irreparable damage that will inexorably affect human life as well.

Biology

Biological notes on plankton

The plankton, being unable to swim effectively, moves thanks to the currents and waves in the so-called pelagic area of ​​the oceans, seas and inland waters (lakes, rivers, valleys, etc.).

Given the heterogeneity of the creatures that make it up, plankton cannot be considered all the same. One can differentiate according to the occupation in the water column (necton and benthos), to the capacity of locomotion, to the phase of development (some creatures are plankton only at a young age, such as fish, sea urchins, starfish, etc.), to the biological realm to which it belongs (zooplankton, phytoplankton, unicellular bacteria and algae) and to its size.

Below we will propose two of the most important classification systems.

Classification of plankton in functional or trophic groups

Plankton is divided into various functional groups (or trophic groups). This criterion differentiates the planktic community in large groups of producers, consumers and recyclers. However, determining the trophic level of plankton is not easy. For example, although most dinoflagellates are photosynthetic producers or heterotrophic consumers, many species play both roles. In this mixed trophic strategy (known as mixotrophy) the organisms act both as producers and as consumers, moving from one feeding method to another in response to environmental conditions. For example, relying on photosynthesis when nutrients and light are abundant, to move to predation when growth conditions become adverse. The recognition of the importance of mixotrophy as an ecological strategy is constantly increasing, as is the extent of the role it can play in marine biogeochemistry.

Subdivision of plankton in size

Plankton is also divided by size.