Introductory Chapter: General Overview on Oceanography

*Leonel Pereira and Miguel A. Pardal*

### **1. Introduction**

Spherical, gigantic, bright blue with large whites in areas of clouds, ice, and storm spirals. This is the Earth seen from space by an astronaut. Blue corresponds to the ocean that moderates the temperature, significantly influences the climate, and ensures the maintenance of life as we know it today. The human population has used the ocean since the beginning of the times, and the conquest of the seas is directly related to the evolution of human society, which establishes the movement of people relative to the sea, raw material, food, commodity/trade exchanges, energy, and as a waste disposal area, unfortunately currently contributing to the effects of climate change. About 6,24 billion people (78% of the world's population) live within a radius of 200 km from the sea, making up the largest metropolises on the planet, almost all of which are directly connected to the ocean [1].

Seas and oceans are smaller segments of the only ocean that involves all the emerged land of the planet, divided only for purposes of convenience (social and political) and geolocation. During the Middle Ages, much of the maritime trade was carried out between the Mediterranean sea and other small seas in that region, becoming famous the "Seven Seas," comprising the Adriatic, Arabian, Caspian, Mediterranean, Black and Red sea, and the Persian Gulf [2]. Currently, globalized human civilization, in constant exchange of information, responds with a much broader and more analytical look at the ocean. The new seven seas are made up of the North Pacific, South Pacific, North Atlantic, South Atlantic, Indian, Arctic, and Antarctic oceans. According to the International Hydrographic Organization, there are 61 seas on Earth, such as the Caribbean Sea (Central America), North Sea (Northern Europe), Gulf of Mexico (Mexico and USA), Bering Sea (between America and Asia), Persian Gulf (in the Middle East), and Hudson Bay (Canada and USA) [3].

Seas and oceans together cover 71% of the Earth's surface, which corresponds to an area of 361,100,000 Km2 and a volume of 1,338,000,000 Km3 (**Table 1**). Its deepest point is the Mariana Trench, 11,022 m deep in the Pacific, and the highest point is in the Hawaiian Marine Range (USA), a sea mountain 10.203 m high from the ocean floor (**Figure 1**). On average, the ocean has a layer 3796 m thick, with a temperature of 3.9°C and a salinity of 34.482 g of salt per liter of water, usually at a salinity of 35. In comparison, the surface land is only one thickness of 840 m and the Himalayan range (Nepal) with 8848 m. The deepest point, among all continents, is in Siberia (northern Russia), Lake Baikal with 1680 m deep, which dams 20% of the planet's fresh melting water [4].


#### **Table 1.**

*The proportions of water mass on the planet are distributed differently throughout the planet, whether in solid (ice), liquid (ocean, rivers, lakes, groundwater), or gaseous (atmospheric vapor) form.*

#### **Figure 1.**

*About 71% of the surface of the planet is covered by the ocean, and this volume corresponds to 97% of all the water in the Earth's crust.*

While the ocean may seem incredibly large, on a planetary scale, it is insignificant. In an image that portrays the surface of the Earth covering a paper globe of 12 cm in radius, the oceans would only represent the thin layer of blue ink that colors the paper, considering the 12 cm radius of the planet. The ocean accounts for about 0.02% of the planet's mass. There is an immensely greater volume of water inside the planet than in the ocean, atmosphere, and rivers. The Northern Hemisphere has

60.7% of its surface area of sea and 39.3% of land, the largest portion of emerged land. In the Southern Hemisphere, its largest area is destined to the sea with 80.9%, and only 19.1% of land (**Figure 1**).

Oceanography is important because the oceans play a critical role in global climate, producing oxygen, regulating sea levels, and creating habitats for millions of marine species. In addition, the oceans are a vital source of food, energy, and mineral resources for humanity. For these reasons, oceanography is a fundamental science for understanding and sustainably managing the oceans and their resources [5].

### **2. First navigations**

Historically, civilizations that used maritime transport (mobility or food) had greater development and greater territorial borders in relation to other cultures. The first written records of maritime trade date back to 2000 BC in the Mediterranean sea. The Cretans were the first people to establish maritime supremacy in the Mediterranean. After the fall of this empire in 1200 BC, the Phoenicians gained control and expanded the commercial zone beyond the Straits of Gibraltar. Greek culture began its dominance of the Atlantic Ocean in 900 BC. They were the first to observe a north-south current beyond Gibraltar, considering all this body of water as an immense river, called the "Okeanos." However, these expeditions were closely associated with the coastal zone, very few ventured high sea. On the other side of the world, other peoples also took to the sea, such as the Chinese, who developed a complex waterway system that connected the various rivers to the Pacific Ocean. It is estimated that in 3000 BC. Polynesian peoples already moved easily between the islands of present-day Indonesia and South Asia, starting the colonization of islands in the central portion of the Pacific. These "sailors" were based simply on observing the Sun and stars during dawn and dusk [6].

Trade and the conquest of new lands promoted travel increasingly ambitious, long, and far from the coast. It is undeniable that marine science had its beginnings linked to simple observations described by navigators. In 300 B.C., the largest library in the history of the ancient world was founded, with the largest collection of parchments, the Library of Alexandria (Egypt), considered the first university on the planet. Due to this source of information, marine sciences had a great leap forward in their applied studies. One of the most famous librarians who managed the library was the Greek Eratosthenes of Cyrena, the first to remarkably calculate the circumference of the Earth. Although Pythagoras had already reached the conclusion that the planet was round in 600 BC, it was Eratosthenes who estimated its size. The original figure published by the librarian in 230 B.C. differs by only 8% from the currently calculated real value (40.075 km) [7].

#### **2.1 Scientific navigations**

The first documented scientific expedition took place between 1768 and 1771, under the English flag of Captain James Cook, on the ship HMS Endeavor. Although the expedition had several goals, scientific observation was one of them. It was on this expedition that they "discovered" New Zealand and mapped the Great Australian Barrier Reef. The success of his first voyage resulted in two other expeditions: one (between 1772 and 1775) to the extreme south, being the first navigator to circumnavigate the world at high latitudes, which "discovered" Easter Island and reached latitude 71°S, although it did not find Antarctica. His last expedition was between

1776 and 1779, with the aim of exploring the high latitudes of the North (Canada, Alaska, and Siberia). On this voyage, Cook "discovered" Hawaii and charted the west coast of North America. He and scientists from the British Royal Academy collected samples of plants, animals, various marine organisms, and samples from the ocean floor. The detail in the description of your Pacific nautical charts is so accurate that it helped the Allies during World War II [8].

All of the above expeditions promoted great advances in marine science, even though none of them had academic research as their main objective. The first circumnavigation expedition with the exclusive main objective of marine sciences was the British ship HMS Challenger of 1872–1876. Another famous previous expedition, that of the ship HMS Beagle, was commanded by Captain Robert FitzRoy and naturalist Charles Darwin between 1831 and 1836. This resulted in remarkable discoveries for the theory of the evolution of life on the planet, but it was mainly focused on experiments and continental samplings, C. Darwin's bestseller The Origin of Species (published in 1859), was one of the fruits of this splendid expedition, which inspired the future Challenger [9].

### **3. Physical oceanography**

Physical oceanography is the part of oceanography that focuses on understanding the physical properties of the oceans, such as temperature, salinity, current, swell, and depth. These properties affect the circulation of ocean currents, the formation of islands, and continents, marine life, and the interactions of the oceans with the atmosphere and climate [10].

Physical oceanography focuses on understanding how temperature, salinity, and current affect the circulation of ocean currents. Ocean currents are important because they affect the global climate, help transport nutrients, and regulate sea levels. Physical oceanography also studies waves, including how they are generated, how they propagate, and how they affect marine life [11].

Physical oceanography also focuses on understanding the depth of the oceans and undersea topography. This includes the formation of seamounts, island chains, and the cycles of erosion and sediment accumulation. Undersea topography is important because it affects current circulation, carbon dioxide production, and marine life [12].

In addition, physical oceanography studies the interactions between the oceans and the atmosphere, including how the oceans affect global climate and how they are affected by climate. For example, oceans can affect global climate by transporting heat and water vapor, and climate can affect oceans through precipitation, evaporation, and ice formation [13].

In summary, physical oceanography is an important part of oceanography that focuses on understanding the physical properties of the oceans and their interaction with the atmosphere and climate. This is crucial to understanding how the oceans affect and are affected by the global climate and to ensure the sustainable management of marine resources [14].

#### **3.1 Atmospheric circulation**

The sun and atmosphere directly or indirectly control almost all dynamic processes within the ocean. The dominant external factors and energy sinks are sunlight, evaporation, infrared radiation emission from the ocean surface, and the ocean's

#### *Introductory Chapter: General Overview on Oceanography DOI: http://dx.doi.org/10.5772/intechopen.113821*

sensible heat from hot and cold winds. Winds control the surface circulation of the ocean down to about 1 km of depth. Wind and tides drive deep ocean currents [15].

The ocean, in turn, is dominated by a heat force that conducts atmospheric circulation differently from the equator to the poles. The uneven distribution of heat balance (loss and gain) across the ocean drives winds through the atmosphere. The sun heats the tropical ocean, which evaporates, transferring heat in the form of water vapor to the atmosphere. Heat is released when the steam condenses into rain. Winds and ocean currents transport heat toward the poles, where it is lost to the atmosphere [16].

Air heats up, expands, and rises at the equator; in the same way that it cools, contracts, and performs downward movement at the poles. However, instead of continuing from the equator to the poles continuously in each hemisphere, air rising at the equator is gradually deflected eastward as it moves poleward, that is. the air turns to the right in the Northern Hemisphere (NH) and to the left in the Southern Hemisphere (SH). This change in direction is caused by the Coriolis effect (a real effect that depends on the frame of reference), which, despite not causing the wind, influences the direction [17].

From the moment the air rises at the equator, a decrease in humidity by precipitation (rain) caused by the cooling and expansion. This drier air then becomes denser in the upper atmosphere as it begins to radiate heat into space and cools. After moving from the equator to about 30°N and 30°S latitude, the air becomes dense enough to descend to the Earth's surface. A large portion of the descending air returns toward the equator when it reaches the surface. In the NH, the Coriolis effect influences the direction of surface air to the right. Despite being warmed by compression during its downward movement, air is normally cooler than the surface it flows through. As a result, the air warms up as it moves toward the equator but evaporates surface water and becomes humid. This moist, heated, and less dense air begins to rise as it approaches the equator, closing the cycle. This significant air loop is called the atmospheric circulation cell. There are two cells in the tropics (0° to 30°): Hadley cells. Two cells at mid-latitudes (between 30° and 50–60°): Ferrel cells and two cells at high latitudes (50–60° up to 90° - poles): polar cells. These three large atmospheric circulation cells described are also represented by the trade winds (northeast and southeast), west winds, and east winds, respectively [18].

This atmospheric circulation model described provides a very interesting understanding for physical oceanography. From understanding of these atmospheric dynamics, it is possible to extend the study to various phenomena or processes that occur in the earth-ocean-atmosphere system, such as monsoons, breezes (sea and land), storms, cyclones (tropical and extratropical), and even phenomena, such as "El Niño" and "La Niña" (also correlated with oceanic circulation) [19].

#### **3.2 Oceanic circulation**

As seen in the description of atmospheric circulation, there is an energy or heat balance between the equator and the poles through the atmosphere and oceans. This interface is extremely important. This energetic (or thermal) balance is essential for the dynamics of winds and ocean circulation. Energy transport across the oceans *via* ocean currents accounts for 10 to 20% of the heat distribution across the planet. Basically, sea water moves in currents, either shallow or deep. Surface currents affect only the shallowest tenth of the oceans, and their movement is influenced by heat balance and winds. In general, the movement of surface currents is horizontal, and they can also flow vertically according to the wind that blows near coastal regions or along the equatorial

region. Surface currents flowing from the equator (low latitudes) transport heat to the poles (high latitudes), nutrients, and influence climate and weather. In addition, they are essential for navigation. Deep oceanic or thermohaline circulation is driven by density differences between water masses. Remembering that the density in the oceans is defined by the relationship between temperature, salinity, and pressure (due to the great depths). This circulation accounts for 90% of sea water below the surface layer [20].

In general, the Coriolis effect, the force of gravity and friction influence movement (direction, up and down, and intensity/velocity) of surface and deep ocean currents (thermohaline). The oceans are interconnected but do not perform significant water exchange between them, and this fact occurs because the water masses have different oceanographic characteristics (temperature, conductivity, salinity, heat balance), wave dynamics, tides, and currents that differ throughout the planet. Therefore, the oceans are divided into five large portions: Atlantic, Pacific, Indian, Arctic, and Antarctic [21].

### **4. Geological oceanography**

Geological oceanography is an interdisciplinary area that combines knowledge from geology, oceanography, geophysics, geochemistry, geomorphology, and sedimentology. Its aim is to understand how the geological features of the oceans and seafloor emerged and how they evolved over time [22].

One of the main techniques used in geological oceanography is seismic, which involves the emission of sound waves that are reflected from different underground layers, allowing scientists to obtain a three-dimensional image of the marine subsoil. Other techniques include taking sediment samples, using sonar to map the seafloor, and conducting underwater drilling [23].

Geological oceanography is also important for understanding the evolution of undersea sedimentary basins, which are large areas of sediment deposition, and for studying undersea volcanic eruptions and undersea earthquakes. This information is critical for predicting potentially dangerous geological events, such as tsunamis, and for properly managing coastal zones and marine resources, such as oil and natural gas [24].

The coastline is one of the most dynamic natural features on the planet. Its position in space constantly changes on temporal scales of seconds (waves), hourly (high tides and low tides), daily (storms), seasonal (seasons of the year), annual (El Niño), decadal, secular, and millennial. The daily rise and fall of sea level and other bodies of water connected to the ocean (estuaries, lagoons, etc.) are caused by the interference of the Moon and the Sun on the Earth's gravitational field. The amplitude of the tides (the difference in level between high and low tide) is a modeling element of the coastline, as a function of the current velocities associated with it. These tidal currents are significant in coastal sediment transport. Tidal currents have the capacity to modify the morphology of the coastline and the inner continental shelf [25].

Geological oceanography also plays an important role in understanding marine biodiversity and protecting marine ecosystems. Undersea geology can influence ocean currents, temperature, and the chemical composition of water, which has implications for marine life. In addition, geological oceanography can help identify and protect areas with high biodiversity and critical habitats for marine life [26].

In summary, geological oceanography is an important field that provides a fundamental understanding of the evolution of the Earth and oceans, as well as the interactions between human activities and the marine environment [14].

## **5. Chemical oceanography**

Chemical oceanography is the branch of oceanography that focuses on the study of the chemical composition of the oceans and their relationship to the Earth and climate. The oceans are an important source of elements and chemical compounds that are essential for life on Earth, and chemical oceanography seeks to understand how these elements and compounds are distributed, transported, and transformed within the oceans [27].

Chemical oceanography focuses on issues such as the variation in the concentration of salts, the formation of chlorides, the concentration of carbon and other elements, as well as the interaction of these components with the atmosphere, continents, and marine life. In addition, chemical oceanography also investigates the chemistry of the deep oceans, including the chemical composition of the water, the concentration of metals, and the presence of organic compounds [28].

### **5.1 Water**

Water is a molecule formed by chemical bonds between two hydrogen atoms and one oxygen. Because of the arrangement of hydrogen and oxygen atoms, water has angular geometry, making it polar. Thus, its positive part attracts negative particles, while the negative attracts positive particles. Water has intriguing characteristics, which make it a compound, despite being abundant, so special and unique [29]:


Marine systems undergo changes in their chemical composition due to changes in the environment, usually associated with the entry of contaminants. It should be remembered that the environmental quality can be altered by the presence of these toxic agents. The main anthropogenic inputs found refer to the dumping of dredged material, urban and industrial effluents, leaching from rural areas, atmospheric inputs, and shrimp farming waste [30].

### **5.2 Chemical oceanography and the climate change**

Chemical oceanography has important implications for understanding climate as the oceans are an important climate regulator, storing and transporting large amounts of heat and carbon dioxide. Chemical oceanography is also important for understanding biogeochemical cycles, including the carbon cycle and nutrient cycle, which are fundamental to marine life [31].

*Introductory Chapter: General Overview on Oceanography DOI: http://dx.doi.org/10.5772/intechopen.113821*

Chemical oceanographers use a variety of techniques to collect and analyze samples of water and marine sediments, including chemical analysis techniques, spectroscopy, and remote sensing. This information is important for the management of marine resources such as fisheries, tourism, and oil and natural gas exploration, as well as for understanding marine biodiversity and the health of marine ecosystems [32].

In summary, chemical oceanography is an important field that provides a fundamental understanding of ocean chemistry and its relationship to climate, marine life, and the wider environment.

### **6. Biological oceanography**

Biological oceanography encompasses a wide range of disciplines from molecular biology to ecology to better understand the functioning of marine ecosystems and their inhabitants. Some key areas of study include [33]:


Biological oceanography also investigates the impact of human activities on the marine environment and its inhabitants, such as the effects of pollution, overfishing, and climate change [34].

The energy that most marine organisms need to survive comes directly or indirectly from the Sun. This produces enormous amounts of energy, which is captured by the chlorophyll present in organisms called primary producers. Solar energy is then transformed into chemical energy. From these reactions, energy is used to synthesize carbohydrates and other organic molecules that will be used by the producers themselves or will be ingested by other microorganisms present in the aquatic environment called consumers [35].

Photosynthesis is the main autotrophic process carried out by beings possessing chlorophyll, represented by plants, some protists, photosynthetic bacteria, and cyanobacteria. The rate of photosynthesis varies depending on the available light (intensity and quality), in addition to other factors, such as the amount of biomass, nutrients, etc. This process is considered dominant in the conversion of energy into carbohydrates, but energy production may also occur through inorganic molecules available in the medium instead of sunlight. We call this process chemosynthesis, and it is present in some marine forms, but it is small in relation to photosynthesis [36, 37].

Primary productivity, synthesis of organic matter from inorganic substances, is expressed in grams of carbon assimilated into organic matter per square meter of ocean surface per year (gC/m2 /year). In this context, we call primary producers the autotrophic organisms capable of synthesizing food. The heterotrophic animals that consume these organisms are called secondary consumers, while the animals that feed on these organisms are called tertiary consumers, and so on up to the top consumers. It is important to note that as energy flows, much of it is lost as heat. The energetic interactions between producers and consumers are generally complex, which is why they are called food webs [38].

### **6.1 Pelagic organisms**

Pelagic organisms live suspended in sea water, adrift, and interact in this place with members of very different sizes and characteristics. In this habitat, they share the need to maintain an upright position, in addition to obtaining food, among other basic needs. According to the form of life, we can divide the pelagic organisms into plankton and nekton [39].

Plankton is constituted by the group of beings that live suspended in the water, carried by the current, in aquatic environments of fresh, brackish, and marine water. Many of these organisms have their own movement but insufficient to overcome the force of the currents. Plankton organisms range from micrometers invisible to our eyes without the use of a microscope, to millimeters, with some exceptions of organisms that can reach from several centimeters to meters in length, such as the "Portuguese Man-of-War" (Physalia physalis) [40].

Plankton can be grouped depending on some characteristics:


The phytoplankton community guarantees the ecological balance of the aquatic environment as it forms the basis of the trophic network and of all biological production in the seas. It is a group with a high degree of biodiversity, and new species are

isolated and described every day. The microbial food chain of marine ecosystems extends throughout the entire photic zone of the oceans (where the presence of light reaches, up to 200 m deep on average), and it is also known as the microbial loop [41].

The trophic relationships of the loop group different microorganisms, which are mainly responsible for the processes of decomposition and remineralization of the compounds of the biogeochemical cycles [42].

Several other ecological actions can be performed by phytoplankton (adapted from [43]):


Marine biodiversity is high in the pelagic environment as the plankton has a high species richness in addition to being in large numbers, usually greater than 30 coinhabitants in space and time unlike terrestrial ecosystems. This ability to inhabit the same ecological niche seems to be a paradox, but it can be explained by the great heterogeneity in the pelagic environment, providing the existence of micro-niches for different species [44].

The lack of knowledge about the life cycle of many planktonic microorganisms makes it difficult to recognize their real species. Ideally, organisms are identified based on morphological criteria (shape and size), ultrastructure, biochemical makeup (chemotaxonomy), and genetics. There is a consensus that the genetic constitution of organisms, details of ultrastructure, and the life cycle should, together, serve as a reference to determine phylogeny, and that phylogeny should determine taxonomy. Thus, the nomenclature should reflect the genome information. This ideal is still far away for protist and prokaryotic organisms and, in practice, the morphospecies are still of great importance in determining the diversity of phytoplankton and proto-zooplankton [45].

How many species are there? In addition to most microscopic species still being unknown, the exact number is unknown, as new species are described daily. Major advances were determined by the introduction of electron microscopy around 1970 and currently by molecular biology. There are at least eight major groups of phytoplanktonic organisms, the most important of which are diatoms (Bacillariophyta) and dinoflagellates (Miozoa). Other prominent groups are Coccolithophyceae and Cyanobacteria [46].

Primary production (PP) in the oceans can be divided into primary gross (the total organic matter produced, excluding the cellular respiration that occurred during the given period) and net primary (organic matter produced is accounted for discounting the "loss" by respiration). Some physical factors may interfere with primary production, such as the primary production rate approximately following the behavior of light with increasing depth of the environment (negative exponential curve). In the euphotic layer, the rate of photosynthesis is high, decreasing to the boundary of the euphotic layer, where the rate of photosynthesis approximately corresponds to the rate of respiration (net primary production = zero). Below the euphotic layer, respiration exceeds photosynthesis and therefore autotrophic cells do not grow [47].

In the marine environment, water column stability is important in phytoplankton and macroalgae (in coastal waters) ecology. The presence of a thermocline or halocline determines stability in the surface and illuminated layer, allowing phytoplankton cells to be exposed to light and providing high gross and net primary production. In conditions of vertical mixing in the water column (isotherms and isohalines), phytoplankton cells are displaced, remaining part of the time in the dysphotic (low light) or even aphotic layer, thus decreasing primary production. The relationship between light, primary production, and respiration in the water column is described by the Sverdrup model. In this model, the concept of critical depth (first defined by Sverdrup, 1953) stands out, that is. the depth at which the production of the entire water column is equal to the total respiration (**Figure 2**) [48].

#### **Figure 2.**

*Light penetration (of different wavelengths) in the sea water column (coastal zone) and the vertical distribution of macroalgae.*

Chemical factors also influence PP since phytoplankton actively incorporate inorganic nutrients by using enzymes associated with the cell membrane. The main nutrients or elements required for nutrition can be classified in different ways [49]:


Another group of great ecological importance in plankton is the called zooplankton, in which heterotrophic organisms that feed on primary producers and other zooplankton organisms participate. Formed by animals and larvae of numerous species, the vast majority microscopic, have a certain ability to move in the oceans and seas. The locomotion capacity of zooplankton can be verified with the vertical migrations present in some organisms. It can be classified into two groups:


Most of the organisms that make up the zooplankton feed on microalgae, although carnivores, omnivores, and detritivores are observed in addition to herbivores. On the other hand, they are food for many species of fish and other animals, such as the whale, which feeds almost exclusively on krill (pelagic arthropod), considered a key species in the Antarctic ecosystem. They are considered essential organisms for the maintenance of the aquatic ecosystem as are at the base of the food chain [50].

### **6.2 Nektonic organisms**

Pelagic animals, which actively swim in the water column, are known as nektonic beings. Most are vertebrates (mainly fish), but some invertebrates are present in this classification, such as squid and some crustaceans. Turtles and mammals can be important species in certain areas, as can seabirds, especially as predators. The main groups of nektonic predators are:

• Cephalopods: They are the most evolved animals among mollusks, with many marine predators formed by squid, *Nautilus,* and *Octopus*. They are a source of great fisheries.


populations of their prey species. These two factors, relevant global biomass and regulatory role, make them a fundamental component of the marine environment. This fact makes them if particularly important if we consider that, currently, about 23% of marine mammal species are threatened [51].

All marine mammals share four common characteristics: a hydrodynamic body, with appendages adapted for swimming; modified breathing system to retain large amounts of oxygen during long dives and displacements. Another important point is the ability to generate internal heat through high metabolic rates and conserve it through insulating layers of fat, and in some cases, even with the presence of hair. The fourth adaptation is related to the absence of need for fresh water due to the ability of their kidneys to excrete urine concentrated in salts, allowing the water necessary for their metabolism to derive from the oxidation of food [52].

The order Cetacea (cetaceans and sirenians) has the only mammals' marine animals that spend their entire lives in the water. Unlike pinnipeds, which mainly use hair as thermal insulation, cetaceans have a thick layer of fat, the "blubber." Hind limbs are absent, and propulsion is provided by horizontal caudal fins. The forelimbs do not have externally individualized fingers, having the shape of oars, and are used to maintain stability during swimming. They are divided into two suborders: Odontoceti and Mysticeti. Current true whales (raw whales) are characterized by their highly differentiated feeding apparatus due to the loss of teeth and the appearance of cornified epithelial tissue plates (fins) that are suspended from the roof of the mouth and serve to filter food from the water. This suborder Mysticeti includes right whales, gray whales, and pygmy right whales, while the suborder Odontoceti includes beaked whales, sperm whales, porpoises, Amazon River dolphins, killer whales, pilot whales, and belugas, as well as of dolphins [53].

#### **6.3 Benthic organisms**

They are those animals and plants that live associated with the sediment. Some can burrow (infauna), and others live on the surface of the sediment (epifauna). The benthic habitat can be shallow or deep, full of food, or somewhat barren; the fact is that the diversity of benthic habitats, and of organisms that live associated with them, is very large. Macroalgae forests, rocky intertidal zones, sandy beaches, marshes, and even coral reefs are part of this vast habitat [54].

The epifauna comprises the animals that live on or associated with rocks, stones, shells, vegetation, or on unconsolidated backgrounds. The infauna comprises all animals that live within the unconsolidated substrate layer, drilling into it, or simply living within it. There are still other ways to classify benthic organisms:


*via* nutritional aspects (ex: Filters are more frequent in sandy bottoms, where their filtration devices are not at risk of being clogged). In this way, the type of substrate, where the animal lives can modify the rate and forms of reproduction. The horizontal distribution on sandy bottoms is affected by the nature and size of the grains; the type, quantity, and form of organic matter associated with the substrate; the total area of the sandy substrate; and other environmental factors such as water movement, light, salinity, oxygen supply, and pressure.

### **7. Bioactive marine natural products**

One of the fields with a successful history within Marine biotechnology is the bioprospecting of bioactive marine natural products. This subarea stands out as one of the most developed, with several substances being used commercially, and many others in preclinical and experimental testing phases. Until the 1950s, the marine environment went unnoticed by natural product scientists, mainly due to its difficult access. But it was from the 1970s onwards, with the advancement of diving techniques and equipment, that marine organisms became part of chemistry and pharmacology laboratories, starting their history [55].

The first efforts in the exploration of marine natural products were focused on easily available and collectible organisms, such as brown, green, and red algae, sponges, and soft corals, which quickly showed to produce a great variety of new molecules. With continued exploration, in partnership with the progress of oceanographic technology, other groups of organisms, more critical in terms of availability, were studied, and the arsenal of unique molecules from the marine environment grew [56].

In general, the exploration of marine natural products resulted and continues to result in the discovery of many substances, most designated for the pharmaceutical industry, but also occupied space in the areas of cosmetics, agriculture (pesticides), and shipbuilding (antifouling's) [57].

#### **7.1 Biopolimers**

Products made from nonbiodegradable polymeric materials (such as plastic), which come from fossil sources, have become a problem due to the growing number of inappropriate discards, and the degradation time of these materials, which take many years in the environment. Researchers have been looking for alternatives, together with the industry, to minimize the environmental impacts caused by the inappropriate disposal of plastic products. Among the alternatives, in addition to reuse and recycling, the production and use of biopolymers, biodegradable polymers, and green polymers have been growing due to their technical and economic viability, presenting great potential for expansion. They can come from renewable sources, such as cellulose, potatoes, or be synthesized by bacteria from small molecules, or even be derived from animal sources, such as chitin or proteins [58].

Crustaceans, such as shrimp and crabs, produce chitin, the second most abundant polysaccharide in nature, after cellulose. Chitin is a very versatile substance for industrial application, in addition to being useful in other areas. It is used in the composition of agricultural fungicides. In medicine, it is used for the manufacture of hemodialysis membranes, in biodegradable surgical threads, as substitutes for artificial skin, healing for burns, and medicine capsules and insulin releasers. In cosmetics,

#### *Introductory Chapter: General Overview on Oceanography DOI: http://dx.doi.org/10.5772/intechopen.113821*

chitin is used in the manufacture of shaving creams and moisturizing creams. Due to its ability to absorb fats, chitin is present in the composition of several dietary foods. It is also used in papermaking and the textile industry. The flocculant and coagulant actions of chitin are applied in the filtration of water in swimming pools, in water sanitation, and in the removal of heavy metals and oils [59].

Marine algae (seaweeds) represent one of the most abundant sources of relevant and widely used biopolymers. Agar, used in research as a raw material for gels and biological matrices; carrageenans, used as stabilizers and texturizers by the food industry and in cosmetic and hygiene product formulations; alginic acid, used as a biomaterial in medical sciences for skin grafts, dressings, and healing agents for serious cases, such as burns, as well as a vehicle for administering drugs or gene therapy and as a base in the preparation of dishes in gastronomy (**Figure 3**). Some mussels and barnacles have been explored for their adhesive properties for fixing on consolidated substrates. This type of "glue," produced mainly by barnacles, has been used in surgical procedures, replacing the suture [60].

Seaweeds are used in many countries for very different purposes: directly as food, extraction of phycocolloids, extraction of compounds with antiviral, antibacterial or antitumor activity, and as biofertilizers. Seaweed polysaccharides (phycocolloids), such as agar, alginates, and carrageenans, are produced on a large scale and have a wide range of applications in the food, pharmaceutical, and cosmetic industries.

**Figure 3.** *Main seaweed polysaccharides: A – Alginic acid; b – Carrageenans; c – Agar.*

Many species of seaweed (macroalgae) are used as food and have also found use in traditional medicine because of their perceived health benefits. Seaweed is a rich source of sulfated polysaccharides, including some that have become valuable additives in the food industry because of their rheological properties as gelling and thickening agents (e.g., alginates, agar-agar, and carrageenan). The different phycocolloids used in the food industry as natural additives are (European phycocolloid codes): alginic acid, sodium alginate, potassium alginate, ammonium alginate, calcium alginate, propylene glycol alginate, agar, carrageenan, semi-refined carrageenan or processed *Eucheuma* species, and furcelleran [61, 62].

#### **7.2 Biofuels**

Fossil fuels are responsible for the emission of gases that intensify the greenhouse effect (heating of the earth's atmosphere). The gravity of this fact could be minimized through the indirect use of solar energy to obtain fuels derived from photosynthetic organisms, which can be cultivated practically all over the world, in a renewable and nonpolluting way. Recent research indicates that the production of biodiesel from microalgae could radically change the fuel market. With a much higher oil production potential per area than traditional crops grown on land, microalgae have aroused worldwide interest in prospecting for biofuels [63].

The advantages arising from biodiesel from algae include their fast growth rates and their high yield per hectare, the fact that they do not contain sulfur, are nontoxic, and are highly biodegradable. Productivity is higher in controlled environments (photobioreactors), but other forms of production are also superior for open systems. Significant investment in research is still needed before high levels of productivity can be guaranteed on a commercial scale. In addition to producing oils, algae are also rich sources of vitamins, proteins, and carbohydrates. Several companies and universities are involved in algae biofuels, and in 2020, the development of a systemic approach to the sustainable commercialization of this biodiesel and its bioproducts was announced in USA [64].

In addition to biodiesel, bioethanol also paves the way within the marine biofuels, being produced from cellulose and alginate extracted from macroalgae or from tunicin, a component present in the tunic of ascidians. Sea squirts also contribute to methane production from their biomass [65].

#### **7.3 Bioremediation**

Ecological systems have a level of innate ability to break down contaminants or pollutants that adhere to them. The biological agents responsible for these automatic cleanings are often microorganisms from nature itself. The elimination or breakdown of environmental contaminants by living organisms is called bioremediation. Such microbial-mediated removal over time can take place completely without human intervention; however, the process can also be initiated by anthropogenic administration. The greatest bioremediation efforts in the marine environment are focused on oil spills or other petroleum product contamination, where Marine biotechnology can play a significant role in the final stages of total cleanup [66].

For this case, there are three bioremediation strategies used:

• Intrinsic bioremediation is the removal of oil naturally by biotic means from the environment itself over time and without human intervention.

*Introductory Chapter: General Overview on Oceanography DOI: http://dx.doi.org/10.5772/intechopen.113821*


One of the biggest concerns is the toxic polyaromatic hydrocarbons (PAHs) that make up the tar, found in the oil. Through DNA fingerprinting techniques, researchers have isolated marine bacteria that degrade PAHs. Currently, efforts are being made to understand how communities of natural bacteria can detoxify areas contaminated by hydrocarbons, as well as unravel microbial metabolism and growth in contaminated environments [68].

### **8. Conclusions**

This chapter covers the main aspects of oceanography, the interdisciplinary science that studies the oceans, including their biology, geology, physics, and chemistry. It is an important area for understanding climate change, preserving marine resources, predicting natural events, such as tsunamis, and for safe navigation and fishing. Oceanography is also crucial to understanding Earth's dynamics, and how the oceans affect the global climate. However, much remains to be discovered about the oceans, and oceanography remains an ever-evolving field with frequent discoveries and technological advances. In short, oceanography is a vital area for understanding and protecting our planet and its marine life.

### **Acknowledgements**

Leonel Pereira thanks to the Fundação para a Ciência e Tecnologia, I. P (FCT), under the projects UIDB/04292/2020, UIDP/04292/2020, granted to MARE, and LA/P/0069/2020, granted to the Associate Laboratory ARNET**.**

### **Conflict of interest**

The authors declare no conflict of interest.

*Oceanography – Relationships of the Oceans with the Continents, Their Biodiversity…*

## **Author details**

Leonel Pereira1 \* and Miguel A. Pardal2

1 MARE—Marine and Environmental Sciences Centre/ARNET—Aquatic Research Network, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, Coimbra, Portugal

2 CFE—Centre for Functional Ecology/TERRA Associate Laboratory, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, Coimbra, Portugal

\*Address all correspondence to: leonel.pereira@uc.pt

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

## **References**

[1] Mimura N. Sea-level rise caused by climate change and its implications for society. Proceedings of the Japan Academy. Series B, Physical and Biological Sciences. 2013;**89**(7):281-301. DOI: 10.2183/pjab.89.281

[2] Wu C. "Central nation-peripheral barbarians in four directions-four seas": The geopolitical order of Land-Sea interactions of early Chinese civilization. In: Wu C, editor. The Prehistoric Maritime Frontier of Southeast China: Indigenous Bai Yue and Their Oceanic Dispersal. Singapore: Springer Singapore; 2021. pp. 3-24. DOI: 10.1007/978-981-16-4079-7\_1

[3] Mogias A, Boubonari T, Realdon G, Previati M, Mokos M, Koulouri P, et al. Evaluating ocean literacy of elementary school students: Preliminary results of a cross-cultural study in the Mediterranean region. Frontiers in Marine Science. 2019;**6**:1-14. DOI: 10.3389/ fmars.2019.00396

[4] Olson S, Jansen MF, Abbot DS, Halevy I, Goldblatt C. The effect of ocean salinity on climate and its implications for Earth's habitability. Geophysical Research Letters. 2022;**49**(10):e2021GL095748. DOI: 10.1029/2021GL09574

[5] Claudet J, Bopp L, Cheung WWL, Devillers R, Escobar-Briones E, Haugan P, et al. A roadmap for using the UN decade of ocean science for sustainable development in support of science, policy, and action. One Earth. 2020;**2**(1):34-42. DOI: 10.1016/j. oneear.2019.10.012

[6] The SA. "China seas" in world history: A general outline of the role of Chinese and east Asian maritime space from its origins to c. 1800. Journal of Marine

and Island Cultures. 2012;**1**(2):63-86. DOI: 10.1016/j.imic.2012.11.002

[7] El-Abbadi M. Library of Alexandria. Encyclopedia Britannica. 2023. Available from: https://www.britannica.com/ topic/Library-of-Alexandria [Accessed: February 04, 2023]

[8] Villiers AJ. James cook. In: Encyclopedia Britannica. 2023. Available from: https://www.britannica.com/ biography/James-Cook [Accessed: February 04, 2023]

[9] Egerton FN. History of ecological sciences, part 37: Charles Darwin's voyage on the beagle. The Bulletin of the Ecological Society of America. 2010;**91**(4):398-431. DOI: 10.1890/0012-9623-91.4.398

[10] van Sebille E, Aliani S, Law KL, Maximenko N, Alsina JM, Bagaev A, et al. The physical oceanography of the transport of floating marine debris. Environmental Research Letters. 2020;**15**(2):023003. DOI: 10.1088/1748-9326/ab6d7d

[11] Gonzalez Cruz J, Sequera P, Molina Y, Picon R, Pillich J, Ghebreegziabhe AT, et al. 3.01 - climate and energy vulnerability in coastal regions: The case for US Pacific and northeast corridor coastal regions. In: Pielke RA, editor. Climate Vulnerability. Oxford: Academic Press; 2013. pp. 3-35. DOI: 10.1016/ B978-0-12-384703-4.00302-6

[12] Jørgensen BB, Wenzhöfer F, Egger M, Glud RN. Sediment oxygen consumption: Role in the global marine carbon cycle. Earth-Science Reviews. 2022;**228**:103987. DOI: 10.1016/j.earscirev.2022.103987

[13] Olson S, Jansen MF, Abbot DS, Halevy I, Goldblatt C. The effect

of ocean salinity on climate and its implications for Earth's habitability. Geophysical Research Letters. 2022;**49**(10):e2021GL095748. DOI: 10.1029/2021GL095748

[14] Levin LA, Bett BJ, Gates AR, Heimbach P, Howe BM, Janssen F, et al. Global observing needs in the Deep Ocean. Frontiers in Marine Science. 2019;**6**:1-32. DOI: 10.3389/fmars.2019.00241

[15] Sarker S. Fundamentals of climatology for engineers: Lecture note. Eng. 2022;**3**(4):573-595. DOI: 10.3390/ eng3040040

[16] Ocko IB, Ramaswamy V, Ming Y. Contrasting climate responses to the scattering and absorbing features of anthropogenic aerosol Forcings. Journal of Climate. 2014;**27**(14):5329-5345. DOI: 10.1175/JCLI-D-13-00401.1

[17] Irwin PGJ, editor. Dynamical processes. In: Giant Planets of our Solar System: An Introduction. Berlin, Heidelberg: Springer Berlin Heidelberg; 2003. pp. 133-196. DOI: 10.1007/3-540-37713-1\_5

[18] Why does climate vary from one place to another. Available from: https:// www.climate-policy-watcher.org/ tropical-rainforest/why-does-climatevary-from-one-place-to-another.html [Accessed: February 04, 2023]

[19] Dailidė R, Dailidė G, Razbadauskaitė-Venskė I, Povilanskas R, Dailidienė I. Sea-breeze front research based on remote sensing methods in coastal Baltic Sea climate: Case of Lithuania. Journal of Marine Science and Engineering. 2022;**10**(11):1779. DOI: 10.3390/jmse10111779

[20] Masuda K. Meridional heat transport by the atmosphere and the ocean: Analysis of FGGE data. Tellus A: Dynamic Meteorology and Oceanography. 1988;**40**(4):285-302. DOI: 10.3402/tellusa.v40i4.11801

[21] Davies AM, Xing J, Huthnance JM, Hall P, Thomsen L. Models of near-bed dynamics and sediment movement at the Iberian margin. Progress in Oceanography. 2002;**52**(2):373-397

[22] Kontakiotis G, Antonarakou A, Ruban DA. Geological oceanography: Towards a conceptual framework. Journal of Marine Science and Engineering. 2022;**10**(12):2027. DOI: 10.3390/jmse10122027

[23] Dickinson A, Gunn KL. The next decade of seismic oceanography: Possibilities, challenges and solutions. Frontiers in Marine Science. 2022;**9**. DOI: 10.3389/fmars.2022.736693

[24] Camargo JMR, Silva MVB, Ferreira Júnior AV, Araújo TCM. Marine geohazards: A bibliometric-based review. Geosciences. 2019;**9**(2):100. DOI: 10.3390/geosciences9020100

[25] Haigh ID, Pickering MD, Green JAM, Arbic BK, Arns A, Dangendorf S, et al. The tides they are a-Changin': A comprehensive review of past and future nonastronomical changes in tides, their driving mechanisms, and future implications. Reviews of Geophysics. 2020;**58**(1):e2018RG000636. DOI: 10.1029/2018RG000636

[26] Puerta P, Johnson C, Carreiro-Silva M, Henry L-A, Kenchington E, Morato T, et al. Influence of water masses on the biodiversity and biogeography of Deep-Sea benthic ecosystems in the North Atlantic. Frontiers in Marine Science. 2020;**7**. DOI: 10.3389/ fmars.2020.00239

[27] National Research Council (US) Ocean Studies Board. 50 years of ocean *Introductory Chapter: General Overview on Oceanography DOI: http://dx.doi.org/10.5772/intechopen.113821*

discovery: National science foundation 1950-2000. In: Achievements in Chemical Oceanography. Available from: https://www.ncbi.nlm.nih.gov/books/ NBK208828/. National Academies Press (US): Washington (DC); 2000 [Accessed: February 04, 2023]

[28] Middelburg JJ, Soetaert K, Hagens M. Ocean alkalinity, buffering and biogeochemical processes. Reviews of Geophysics. 2020;**58**(3):e2019RG000681. DOI: 10.1029/2019RG000681

[29] Structure of Water. Available from: https://chem.libretexts.org/Bookshelves/ Introductory\_Chemistry/Introductory\_ Chemistry\_(CK-12)/15%3A\_ Water/15.01%3A\_Structure\_of\_Water [Accessed: February 04, 2023]

[30] Tornero V, Hanke G. Chemical contaminants entering the marine environment from sea-based sources: A review with a focus on European seas. Marine Pollution Bulletin. 2016;**112**(1):17-38. DOI: 10.1016/j. marpolbul.2016.06.091

[31] Lønborg C, Carreira C, Jickells T, Álvarez-Salgado XA. Impacts of global change on ocean dissolved organic carbon (DOC) cycling. Frontiers in Marine Science. 2020;**7**. DOI: 10.3389/ fmars.2020.00466

[32] Weller RA, Baker DJ, Glackin MM, Roberts SJ, Schmitt RW, Twigg ES, et al. The challenge of sustaining ocean observations. Frontiers in Marine Science. 2019;**6**. DOI: 10.3389/ fmars.2019.00105

[33] Bindoff N., Cheung WWL, Kairo JG, Arístegui J, et al. (eds.). Cambridge: Cambridge University Press; 2019. pp. 447-587. DOI: 10.1017/9781009157964.007.

[34] Gitz V, Meybeck A, Lipper L, Young C, Braatz S. Climate Change and Food Security: Risks and Responses. Rome, Italy: FAO; 2016

[35] Sigman DM, Hain MP. The biological productivity of the ocean. Nature Education Knowledge. 2012;**3**(10):21. Available from: https://earth-systembiogeochemistry.net/wp-content/ uploads/2021/05/Sigman\_and\_ Hain\_2012\_NatureEdu.pdf [Accessed: February 04, 2023]

[36] Alberts B, Johnson A, Lewis J, et al. Molecular Biology of the Cell. 4th ed. New York: Garland Science; 2002. Chloroplasts and Photosynthesis. Available from: https://www.ncbi.nlm. nih.gov/books/NBK26819/ [Accessed: February 04, 2023]

[37] Pereira L, Correia F. Algas Marinhas da Costa Portuguesa - Ecologia, Biodiversidade e Utilizações. Paris: Nota de Rodapé Editores; 2015. 341 pp. ISBN 978-989-20-5754-5

[38] Dokulil MT, Qian K. Photosynthesis, carbon acquisition and primary productivity of phytoplankton: A review dedicated to Colin Reynolds. Hydrobiologia. 2021;**848**(1):77-94. DOI: 10.1007/s10750-020-04321-y

[39] Hamner WM. Predation, cover, and convergent evolution in epipelagic oceans. Marine and Freshwater Behaviour and Physiology. 1995;**26**(2-4):71-89. DOI: 10.1080/10236249509378930

[40] Pereira L, Gonçalves AMM, editors. Plankton communities. In: Open Access Peer-Reviewed Edited Book. London, UK, London, UK: Intech Open; 2022. DOI: 10.5772/intechopen.91092

[41] Wetzel RG. 16 - planktonic communities: Zooplankton and their interactions with fish. In: Wetzel RG, editor. Limnology. 3rd ed. San Diego: Academic Press; 2001. pp. 395-488

[42] Heinrichs ME, Mori C, Dlugosch L. Complex interactions between aquatic organisms and their chemical environment elucidated from different perspectives. In: Jungblut S, Liebich V, Bode-Dalby M, editors. YOUMARES 9 - The Oceans: Our Research, our Future: Proceedings of the 2018 Conference for YOUng MArine RESearcher in Oldenburg, Germany. Cham: Springer International Publishing; 2020. pp. 279-297

[43] Araújo GS, Pacheco D, Cotas J, JWAD S, Saboya J, Moreira RT, et al. Plankton: Environmental and economic importance for a sustainable future. In: Pereira L, Gonçalves AM, editors. Plankton Communities. London: IntechOpen; 2022. DOI: 10.5772/intechopen.100433

[44] Costello M, Chaudhary C. Marine biodiversity, biogeography, Deep-Sea gradients, and conservation. Current Biology. 2017;**27**:R511-RR27. DOI: 10.1016/j.cub.2017.04.060

[45] Pinel-Alloul B, Ghadouani A. Spatial heterogeneity of planktonic microorganisms in aquatic systems. In: Franklin RB, Mills AL, editors. The Spatial Distribution of Microbes in the Environment. Dordrecht: Springer Netherlands; 2007. pp. 203-310. DOI: 10.1007/978-1-4020-6216-2\_8

[46] Mora C, Tittensor DP, Adl S, Simpson AG, Worm B. How many species are there on earth and in the ocean? PLoS Biology. 2011;**9**(8):e1001127. DOI: 10.1371/journal.pbio.1001127

[47] Wasmund N, Siegel H, Bohata K, Flohr A, Hansen A, Mohrholz V. Phytoplankton stimulation in frontal regions of Benguela upwelling filaments by internal factors. Frontiers in Marine Science. 2016;**3**. DOI: 10.3389/ fmars.2016.00210

[48] Lindemann C, Backhaus JO, St. John MA. Physiological constrains on Sverdrup's critical-depth-hypothesis: The influences of dark respiration and sinking. ICES Journal of Marine Science. 2015;**72**(6):1942-1951. DOI: 10.1093/ icesjms/fsv046

[49] Mackey KRM, Paytan A. Phosphorus cycle. In: Schaechter M, editor. Encyclopedia of Microbiology. 3rd ed. Oxford: Academic Press; 2009. pp. 322-334. DOI: 10.1016/B978-012373944-5.00056-0

[50] Cavan EL, Belcher A, Atkinson A, Hill SL, Kawaguchi S, McCormack S, et al. The importance of Antarctic krill in biogeochemical cycles. Nature Communications. 2019;**10**(1):4742. DOI: 10.1038/s41467-019-12668-7

[51] Aldemaro R. When whales became mammals: The scientific journey of cetaceans from fish to mammals in the history of science. In: Aldemaro R, Edward OK, editors. New Approaches to the Study of Marine Mammals. Rijeka: IntechOpen; 2012 1

[52] Davis RW. A review of the multilevel adaptations for maximizing aerobic dive duration in marine mammals: From biochemistry to behavior. Journal of Comparative Physiology. B. 2014;**184**(1):23-53. DOI: 10.1007/ s00360-013-0782-z

[53] Favilla AB, Costa DP. Thermoregulatory strategies of diving air-breathing marine vertebrates: A review. Frontiers in Ecology and Evolution. 2020;**8**. DOI: 10.3389/ fevo.2020.555509

[54] Jung S, Chau TV, Kim M, Na W-B. Artificial seaweed reefs that support the establishment of submerged aquatic vegetation beds and Facilitate Ocean macroalgal afforestation: A review. Journal of Marine Science and Engineering. 2022;**10**(9):1184. DOI: 10.3390/jmse10091184

*Introductory Chapter: General Overview on Oceanography DOI: http://dx.doi.org/10.5772/intechopen.113821*

[55] Rotter A, Barbier M, Bertoni F, Bones AM, Cancela ML, Carlsson J, et al. The essentials of marine biotechnology. Frontiers in Marine Science. 2021;**8**. DOI: 10.3389/fmars.2021.629629

[56] Blunt JW, Copp BR, Munro MHG, Northcote PT, Prinsep MR. Marine natural products. Natural Product Reports. 2004;**21**(1):1-49. DOI: 10.1039/ b305250h

[57] Lindequist U. Marine-derived pharmaceuticals - challenges and opportunities. Biomolecules & Therapeutics. 2016;**24**(6):561-571. DOI: 10.4062/biomolther.2016.181

[58] Song JH, Murphy RJ, Narayan R, Davies GB. Biodegradable and compostable alternatives to conventional plastics. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 2009;**364**(1526):2127- 2139. DOI: 10.1098/rstb.2008.0289

[59] Santos VP, Marques NSS, Maia PCSV, Lima MAB, Franco LO, Campos-Takaki GM. Seafood waste as attractive source of chitin and chitosan production and their applications. International Journal of Molecular Sciences. 2020;**21**(12):4290. DOI: 10.3390/ijms21124290

[60] López-Hortas L, Flórez-Fernández N, Torres MD, Ferreira-Anta T, Casas MP, Balboa EM, et al. Applying seaweed compounds in cosmetics, cosmeceuticals and Nutricosmetics. Marine Drugs. 2021;**19**(10):552. DOI: 10.3390/md19100552

[61] Pereira L. Colloid producing seaweeds. In: Kim S-K, editor. Encyclopedia of Marine Biotechnology. New Jersey, USA: Wiley; 2020. pp. 161- 326. DOI: 10.1002/9781119143802.ch8

[62] Lomartire S, Gonçalves AMM. Novel Technologies for Seaweed

Polysaccharides Extraction and Their use in food with therapeutically applications - A review. Food. 2022;**11**(17):2654. DOI: 10.3390/ foods11172654

[63] Bošnjaković M, Sinaga N. The perspective of large-scale production of algae biodiesel. Applied Sciences. 2020;**10**(22):8181. DOI: 10.3390/ app10228181

[64] Sarwer A, Hamed SM, Osman AI et al. Algal biomass valorization for biofuel production and carbon sequestration: A review. Environmental Chemistry Letters. 2022;**20**:2797-2851. DOI: 10.1007/s10311-022-01458-1

[65] Takeda H, Yoneyama F, Kawai S, Hashimoto W, Murata K. Bioethanol production from marine biomass alginate by metabolically engineered bacteria. Energy & Environmental Science. 2011;**4**(7):2575-2581. DOI: 10.1039/C1EE01236C

[66] Ayilara MS, Babalola OO. Bioremediation of environmental wastes: The role of microorganisms. Frontiers in Agronomy. 2023;**5**. DOI: 10.3389/fagro.2023.1183691

[67] Crawford RL. Bioremediation. In: Dworkin M, Falkow S, Rosenberg E, Schleifer K-H, Stackebrandt E, editors. The Prokaryotes: Volume 1: Symbiotic associations, Biotechnology, Applied Microbiology. New York, NY: Springer New York; 2006. pp. 850-863. DOI: 10.1007/0-387-30741-9\_26

[68] Bisht S, Pandey P, Bhargava B, Sharma S, Kumar V, Sharma KD. Bioremediation of polyaromatic hydrocarbons (PAHs) using rhizosphere technology. Brazilian Journal of Microbiology. 2015;**46**. DOI: 10.1590/ S1517-838246120131354

Section 2
