**6.1 Food and nutraceuticals**

The search to food sources are advancing as an indispensable resolve the feed problem, with the continuous world's population grow restricted, by the global restrictions [82]. Phytoplankton aquaculture in an industrial large-scale to human food usage begin with the cultivation of *Chlorella vulgaris* during World War II [80].

According to Pulz and Gross [79], the functional food market using microalgae, in pasta, breads, yoghurts and beverages, is rapidly developing in countries, such as France, United States, China and Thailand. The most common application has been in aquaculture, for the direct or indirect feeding of some species of fish, mollusks, crustaceans and other organisms of economic interest [83].

The consumption of ω-3 obtained from microalgae is beneficial for neural development, in addition to preventing coronary problems, cancer, hypertension, diabetes, cystic fibrosis, arthritis, asthma, schizophrenia and depression. Marine microalgae are capable of synthesizing ω-3 fatty acids, eicosapentaenoic (EPA, C20: 5) and docosahexaenoic (DHA, C22: 6), which enter the marine food chain and are

available in fish oil. These fatty acids are considered important in the development of brain tissue and visual function [84].

Microalgae are the main producers of biomass that accumulate in higher organisms through the food chain. For several centuries, they are used as food in Southeast Asian countries, mainly due to their high protein content. Recently, microalgae have attracted the interest of many researchers due to their structurally diverse bioactive compounds, efficient photosynthetic machinery, greater mass productivity and the absence of competition with arable land and drinking water. They can withstand adverse environmental conditions, producing a variety of biologically active primary and secondary metabolites, such as polysaccharides, carotenoids, omega-3 and 6 fatty acids and phenolic compounds. These metabolites exhibit a series of pharmacological activities, which include therapeutic, drugcarrying and physiochemical properties, including gelation, swelling and emulsification. These may be a new source of functional compounds in the food and pharmaceutical industries [85].

Currently, microalgae are being incorporated into many food formulations. Most of them use microalgae as a marketing strategy or as a coloring agent. As for example, the cyanobacterium Spirulina is not only in fashion, but is rich in several valuable and highly nutritious compounds, such as proteins, PUFAs and bioactive pigments, including chlorophylls, carotenoids and phycobiliproteins. One of the main advantages of natural pigments derived from Spirulina, when compared to their synthetic counterparts, is that the former has several health benefits, and can be used as an ingredient in the development of new functional foods. Proteins from Spirulina have proven to be excellent sources of bioactive peptides with potential application in the functional food industry as antihypertensive, anti-diabetic, anti-obesity and antioxidant ingredients [86] immunomodulatory and anti-inflammatory among other positive bioactivities [87].

Some of the prerequisites for using algae biomass for humans and animals include determining the chemical composition; toxic biogenic substances; nonbiogenic toxic compounds; protein quality studies; biochemical nutritional studies; supplemental value of algae to conventional food sources; health analysis; safety assessments (animal feeding tests); clinical studies (safety test and suitability of the product for human consumption) and acceptability studies [88].

The microalgae used as a food supplement are generally sold in the form of tablets, capsules and liquids or are incorporated in pasta, snacks, candy bars, ice cream, chewing gum, in mixtures of drinks and dyes for natural foods [88, 89]. Foods supplemented with microalgae biomass, when properly processed, can make foods more colorful and tasty, adding not only nutritional value, but also new, unique and attractive flavors [50].

The reasons for this recent growth in interest are cost-effective cultivation and a short cultivation time until the desired compost is obtained. In addition, they have the status generally considered safe and as such do not contain any toxins or pathogens that can be transmitted to humans. [90].

#### **6.2 Feed**

The plankton is a natural source for various animals' species, which are cultivated. Consequently, they are a standard feed source to various farmed species. To other animals, they are non-natural feed source, which is used supplement to be incorporated with normal feed, similarly the plankton usage as human food supply, due to the high quality of protein, minerals, vitamins, carbohydrates and also essential fatty acids to be a high quality feed for fish and others animals [91].

*Plankton: Environmental and Economic Importance for a Sustainable Future DOI: http://dx.doi.org/10.5772/intechopen.100433*

Phytoplankton is a vital player in aquaculture (mariculture) as they are the natural food bases to larvae life stage of various types of mollusks, crustaceans, and fish. The utmost phytoplankton used in aquaculture worldwide belong to the genera: *Chlorella*, *Tetraselmis*, *Isochrysis*, *Pavlova* (Haptophyta, Pavlovophyceae), *Phaeodactylum*, *Chaetoceros*, *Nannochloropsis*, *Skeletonema*, and *Thalassiosira* (Bacillariophyta) [92].

The use of plankton as feed improver was attainment further attention by the I&D research teams and industry to develop feeds to diverse animals (mainly in aquaculture). Which, the main results are the animals feed with plankton gain weight, enhance of triglyceride profile and the protein deposition in muscle, the animal digestibility, starvation tolerance and carcass quality [91, 93].

Phytoplankton can be cast-off as a source of natural pigments for the culture of prawns, salmonid fish, and ornamental fish [91].

#### **6.3 Cosmetic**

The cosmetic area is the third major commercial segment for phytoplankton application, due to the research of natural products to substitute synthetic ingredients. Thus, with cosmetic consumers turning their mindset, the cosmetic segment is one of the main actives to explore the biotechnological potential of the plankton. The natural and ecofriendly predispositions in this area, give an new input to find new high value, innovative and natural formulations for new products, without the imposition of reduced costs as the other areas [80]. The microalgae were not very common in cosmetic, nonetheless, microalgae and their derivatives are in beginning to be integrated in diverse formulas to skin and hair products, through a wide range of functions, such as excipient (stabilizer or emulsifier) or active ingredient. The phytoplankton is usually used in moisturizing, skin whitening, anti-aging, and sun protection creams formulations. However, the pigments from phytoplankton is cast-off as colorant agent for varied cosmetic products [94].

#### **6.4 Bioremediation**

The application of microalgae to bioremediate wastewaters shows a great potential to complement traditional wastewater treatment processes. Furthermore, this approach addresses the need to reduce the costs associated with the growth media expenses for microalgae biomass production [95], through wastewater recycling to obtain microalgal biomass instead of culture medium [96].

Nevertheless, it is necessary to consider possible sources of growth medium contamination, such as grazers which feed on microalgae (**Figure 1a** and **b**), as well as the presence of other microalgae species that can compete or inhibit the target species production.

Bioremediation of numerous pollutants of different characteristics and properties released from the domestic, industrial, agricultural and aquaculture sectors [97, 98]. Moreover, promoting microalgae cultivation in wastewater will help mitigate the environmental impacts of treated effluents since this biological method will complement conventional wastewater treatment and improve not only the removal of organic and inorganic load but also the removal of emerging pollutants, such as pesticides, metals, pharmaceuticals or household cleaning chemicals [99–102].

In addition, they are also capable of removing metals, incorporating them in their cell wall [103] and other noxious compounds such as phenols and chlorophenols [104].

**Figure 1.**

*Microscopic observations of Chlorella vulgaris cultivation in municipal wastewater sludge centrate, (a) with the presence of other microalgae species and (b) with the presence of grazers.*

#### **6.5 Renewables energies**

An emerging area for microalgae biotechnology is environmental applications. This is mainly due to its carbon dioxide mitigation capacity, reducing greenhouse gas emissions that are related to global warming and climate change; and its ability to grow in an effluent liquid that allows wastewater treatment. Today, there is a focus on the use of microalgae in renewable energy as a potential source for the production of biofuels, such as biodiesel, bioethanol, biohydrogen and biogas [105].

It is worth mentioning the importance of the production of biofuels through microalgae. Microalgae naturally contain about 10% lipids. These lipids are mainly present in photosynthetic membranes. Microalgae accumulate lipids in high concentration under "stress" conditions, caused, for example, by the depletion of nutrients such as nitrogen. In the absence of these nutrients, growth is hampered, while energy is continuously received in the form of light. Microalgae channel excess energy into large macromolecules, such as lipids or starch. In these cases, the lipid content can reach 60%. Under stressful conditions, these lipids accumulate in body lipids such as triacylglycerides or neutral lipids. The neutral lipids can be used as raw material for the production of biofuels [106].

During the past few decades, many research studies have covered different technologies to produce biodiesel from lipid-rich microalgae. Under controlled cultivation conditions, microalgae can accumulate metabolites intended to produce various biofuels. For example, starch and various types of oils can be bioaccumulated. Starch extracted from algae is easily hydrolyzed to glucose and used for fermentation in the production of bioethanol. Currently, commercial production of bioethanol from algae is not a viable choice due to the low yield of the product compared to other terrestrial biomasses. The high costs of algae cultivation systems are due to several complex steps: (i) algae cultivation; (ii) harvest; (iii) pre-treatment of biomass; (iv) fermentation; and (v) extraction of bioethanol. By linking all possible improvements at each stage of the process, a substantial advance towards cost-effective algae systems can be achieved in the future [107].

## **7. Conclusions**

This chapter covered the many advantages that plankton have, specifically phytoplankton and zooplankton, their qualities, ecological and economic relevance, *Plankton: Environmental and Economic Importance for a Sustainable Future DOI: http://dx.doi.org/10.5772/intechopen.100433*

as well as their cultivation techniques, aiming the production of add-value products with industrial interest.

It is of great need to use all the knowledge presented and apply it in the different branches of ecology, industry or science, aiming the discovery of new products or directing it to a specific study area, being a subsidy of great importance for the environment and/or for the human being.
