Vertical AND Horizontal Zonation IN Ocean PDF

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simple assignmnet regarding vertical and horizontal zonation in oceans
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FUNDAMENTALS OF ECOLOGY | AROOBA JAVED (FA17-BES-015)

VERTICAL AND HORIZONTAL ZONATION IN OCEAN Marine waters cover two-thirds of the surface of the Earth. In some places the ocean is deeper than Mount Everest is high. Marine organisms are not distributed evenly throughout the oceans. Variations in characteristics of the marine environment create different habitats and influence what types of organisms will inhabit them. The availability of light, water depth, proximity to land, and topographic complexity all affect marine habitats. [1] What is zonation? Zonation refers to the patterns that are observed in a community over a distance, based on the distinct fauna and flora found along the area. Although the different zones are characterized by the dominant species inhabiting them, the separation of zones isn’t always a clear straight line, but instead there is some overlapping of species, particularly where the zones meet. Sometimes, however, the overlapping can disappear or be very small if one species completely out-competes the others by predation or competition over resources, and we can see clear-cut zonation. [2] In marine ecosystem, different zones are formed mainly due to environmental factors such as temperature, wind exposure, light intensity, wave action, and salinity. DIVISIONS OF THE OCEAN Oceanographers divide the ocean into zones both vertically and horizontally. Vertical Divisions Scientists define the water column by depth. They divide the entire ocean into two zones vertically, based on light level. Large lakes are divided into similar regions.  

Photic zone Aphotic zone

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Photic Zone Sunlight only penetrates the sea surface to a depth of about 200 m, creating the photic zone ("photic" means light). The thicknesses of the photic and euphotic zones vary with the intensity of sunlight as a function of season and latitude and with the degree of water turbidity. Organisms that photosynthesize depend on sunlight for food and so are restricted to the photic zone. [3] The photic zone is divide in to further zones based on depth.  

Epipelagic zone – Extends from the shoreline down to 200m. Productivity is quite high in the presence of nutrients due to availability of sunlight. Water is warm. Mesopelagic zone-Extends from 200-1000m. Little light is available. Water temperature is cold and oxygen poor.[4]

Climate The temperature in this zone ranges from 104 to 27 degrees Fahrenheit. Temperature of the oceanic water general decreases with depth. Density and salinity of this zone is low. [6] It corresponds roughly to the layer above the compensation point, i.e. depth where the rate of carbon dioxide uptake, or equivalently, the rate of photosynthetic oxygen production, is equal to the rate of carbon dioxide production, equivalent to the rate of respiratory oxygen consumption, i.e. the depth where net carbon dioxide assimilation is zero. FLORA There is sufficient sunlight that illuminates this zone and to carry out photosynthesis by phytoplankton and plants. Main algae and plants that live in the euphotic zone are: Algae   

Green algae(sea weed) Brown algae Red algae

Plants  

Mangroves Sea grasses [6]

Mangroves A mangrove is a shrub or small tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves occur worldwide in the tropics and subtropics. Adaptations 1. Low Oxygen:

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Black mangroves live on higher ground and make many pneumatophores (specialised rootlike structures which stick up out of the soil like straws for breathing) which are also covered in lenticels. The roots also contain wide aerenchyma to facilitate transport within the plants. 2. Limiting salt intake: Red mangroves exclude salt by having significantly impermeable roots which are highly suberized (impregnated with suberin), acting as an ultra-filtration mechanism to exclude sodium salts from the rest of the plant. Red mangroves can also store salt in cell vacuoles, white or grey mangroves can secrete salts directly; they have two salt glands at each leaf base (correlating with their name—they are covered in white salt crystals).

3. Increasing survival of offspring: In this harsh environment, mangroves have evolved a special mechanism to help their offspring survive. Mangrove seeds are buoyant and are therefore suited to water dispersal. Unlike most plants, whose seeds germinate in soil, many mangroves (e.g. red mangrove) are viviparous, whose seeds germinate while still attached to the parent tree. [7] Sea grasses Sea grasses are flowering plants (angiosperms) which grow in marine, fully saline environments. Like all autotrophic plants, sea grasses photosynthesize so are limited to growing in the submerged photic zone, and most occur in shallow and sheltered coastal waters anchored in sand or mud bottoms. Most species undergo submarine pollination and complete their entire life cycle underwater. [8] Adaptations Ocean plants have adapted to the salinity by breaking down salt into chlorine and sodium ions. Some plants store the salt and later dispose it via their respiratory process. Many plants live close to the seashore and they may have succulent leaves where they store water in the leaves. The plants use the water to dilute the saltwater concentration. Reducing the leaf surface is another way of adapting to the condition in a saltwater biome. Marsh grass extracts the salt and you can see white salt crystals on its leaves. [9] 3

FUNDAMENTALS OF ECOLOGY | AROOBA JAVED (FA17-BES-015)

FAUNA More than 90% of marine life lives in euphotic zone because autotrophs are present in this zone which are their main food source. Examples of euphotic zone animals include most ocean fish (including sharks and rays), man-o'-war, jellyfish, sea turtles, seals, coral, molluscs and zooplankton. Some bottom-dwellers live in the euphotic zone - this zone is defined in terms of light, not depth. [10]

Figure 1 a shark and a ray

Figure 2 mollusc in a coral reef

Adaptations All the animals living in this zone are highly adapted to their environment. Some of the adaptions are: 1. Countershading Countershading is when an animal is light on its underside and dark on its upper parts. When a predator looks down at a counter shaded animal, it blends into the darker waters; when a predator looks at a counter shaded animal from below, the light underbelly disappears into the light. This adaptation helps camouflage the organism, hiding it from predators and allowing it to sneak up on prey. Most sharks, for example, are counter shaded. [10] 2. Webbed feet and flippers Most animals with webbed feet are aquatic animals who live in, on, or near the water. Webbed feet help them move quickly through the water when they are chasing food or trying to escape from predators.

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Some amphibians and reptiles also have webbed feet, and they use them in the same ways as birds. Webbed feet come in handy for swimming quickly through the water. Crocodiles and alligators have webbed back feet, aquatic frogs, which live in water, have webbed feet.

Figure 3 webbed feet

Flippers are an evolutionary adaptation that allow aquatic and semi-aquatic animals to swim long distances while using less energy. Some marine animals like dolphin, seals, and whales. Penguins also have flippers for swimming.

Figure 4 flippers enable penguins to swims

3. Thick layer of blubber Blubber is a thick layer of fat, also called adipose tissue, directly under the skin of all marine mammals. Blubber covers the entire body of animals such as seals, whales, and walruses— except for their fins, flippers, and flukes. Blubber an important part of a marine mammal's anatomy. It stores energy, insulates heat, and increases buoyancy. [11]

Figure 5 whale blubber

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4. Camouflage Underwater camouflage is the set of methods of achieving crypsis—avoidance of observation —that allows otherwise visible aquatic organisms to remain unnoticed by other organisms such as predators or prey. Marine animals have diverse methods of camouflage like transparency, reflection, countershading, mimesis, self-decoration, distraction and adaptive coloration. [12] 5. Gills As oxygen in the aquatic environment is present in the form of dissolved gas so most of the fish have specialised structure called gills to take up that oxygen. Most fish exchange gases using gills on both sides of the pharynx (throat). Gills are tissues that are like short threads, protein structures called filaments. These filaments have many functions including the transfer of ions and water, as well as the exchange of oxygen, carbon dioxide, acids and ammonia. [13]

Aphotic Zone In the aphotic zone there is not enough light for photosynthesis. The aphotic zone makes up the majority of the ocean, but has a relatively small amount of its life, both in diversity of type and in numbers. Temperatures can range from roughly 0 °C (32 °F) to 6 °C (43 °F).Unusual and unique creatures dwell in this expanse of pitch black water, such as the gulper eel, the giant squid, the anglerfish, and the vampire squid. The aphotic zone is subdivided based on depth. [3] 1. Bathypelagic zone – Extends from 1000-4000m. There is no light excluding that from bioluminescent creatures and occasional lava flows. Biological productivity is low and water is cold.[4] Climate Temperatures in high latitudes range from about 3° to -1° C (37° to 30° F). Elsewhere, normal temperatures range between 5° and 15° C. The zone is characteristically dark except in the clear. Salinities typically range between 34 and 36 parts per thousand in the bathyal zone. At bathyal depths, currents are exceedingly slow, and in many areas bathyal waters deeper than 1,000 m (3,280 feet) are essentially stagnant, resulting in low oxygen concentrations and impoverished faunal levels. Photosynthesis does not occur in bathyal waters as there is no light. [14] Fauna     

Fish – Hag fish, Viper fish, Frill shark, Sleeper shark, Dragon fish, Angler fish. Eels – Swallower eel, Gulper eel Crustaceans – Amphipod, Slime star. Squids – Vampire squid, Elusive giant squid. Whales – Sperm whale [15]

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Adaptations Most fish that live in the bathyal zone are either black or red in colour. This is as a defence against predators—with only minute amounts of blue-green light, red is not reflected and appears black. There is no primary production of plant life in the bathyal zone, so all creatures that live there are carnivorous, eating each other or feeding on carcasses that sink down from above. Some eels have large mouth lined with teeth that are capable of accommodating prey much larger than themselves. No whale species live permanently in the bathyal zone, but sperm whales, with the large proportion of tissue in their heads protecting them from the immense pressures at depth, are capable of diving into the bathyal zone to hunt. They prey on squid, including the giant squid. [15] Many fish in the Midnight Zone have light-emitting organs (bioluminescence), and so they often have very large eyes to absorb as much light as possible. This is an example of evolution, where instead of losing their eyes, they adapted to have bigger eyes. These eyes can help fish distinguish between different species of animals. 2. Abyssopelagic zone – Extends from 4000-6000m depth. No light available and cold water.[4] The abyssal realm is the largest environment for Earth life, covering 300,000,000 square km (115,000,000 square miles), about 60 percent of the global surface and 83 percent of the area of oceans and seas. Climate Abyssal salinities range narrowly between 34.6 and 35.0 parts per thousand, and temperatures are mostly between 0° and 4° C (32° and 39° F). Pressure increases by about one atmosphere (approximately 14.7 pounds per square inch at sea level) with each 10-metre increment in depth; thus, abyssal pressures range between 200 and 600 atmospheres. The oxygen content of abyssal water depends entirely upon the amounts dissolved into it at its polar site of origin. [16] Fauna Animals in this zone include angler fish, deep sea jelly fish, deep sea shrimp, cookiecutter shark, tripod fish and abyssal octopus. [17] Adaptations Abyssal fauna, though very sparse and embracing relatively few species, include representatives of all major marine invertebrate phyla and several kinds of fish, all adapted to an environment marked by no diurnal or seasonal changes, high pressures, darkness, calm water, and soft sediment bottoms. These animals tend to be grey or black, delicately structured, and unstreamlined. Mobile forms have long legs; and animals attached to the bottom have stalks, enabling them to rise above the water layer nearest the bottom, where oxygen is scarce. Abyssal crustaceans and fish may be blind. With increasing depth,

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carnivores and scavengers become less abundant than animals that feed on mud and suspended matter. Abyssal animals are believed to reproduce very slowly. [16] Animals in this zone are bioluminescent. Bioluminescence is the production and emission of light by a living organism. Organism produce their own light as it is very dark, deep down here in this zone. Animals use this light for different reasons like warning to stay away from them, camouflage, some use it as a trap for prey. [18] 3. Hadopelagic zone – Extends from 6000, to the deepest depths in the ocean. No light available and cold water. This area is covered with deep, narrow trenches. [4] Fauna This zone does not spread across the ocean floor but exists only in the deepest ocean trenches. Because no light reaches this part of the ocean, it is impossible for plants to thrive but there are still hardy creatures that call these depths home. Amphipods Amphipods are soft-shelled crustaceans resembling large fleas. They have been found as deep as 9,100 meters below the ocean surface. Feeding on detritus, amphipods are true bottom feeders. Decapods Lobsters, crabs and prawns, these creatures were spotted at around 7,000 meters by scientists. Rat – tail fish Also known as a grenadier, these fish were found at 7,000 meters. Rat-tails have large mouths and a tapering tail which makes them look like giant tadpoles. They also have a welldeveloped sense of smell.

Figure 6 rat tail fish

Challenger Deep

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At 11,034 meters down, Challenger Deep is the deepest point in the ocean. Only one life form has been found there, called protists, these creatures are not actually animals. They are singlecelled organisms believed to be related to the first life forms on Earth. [19] Horizontal Divisions The ocean is also divided horizontally by distance from the shore. 

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Intertidal zone - Nearest to the shore lies the intertidal zone (also called the littoral zone), the region between the high and low tidal marks. The hallmark of the intertidal is change: water is in constant motion in the form of waves, tides, and currents. The land is sometimes under water and sometimes exposed. Neritic zone - The neritic zone is from low tide mark and slopes gradually downward to the edge of the seaward side of the continental shelf. Some sunlight penetrates to the seabed here. Oceanic zone - The oceanic zone is the entire rest of the ocean from the bottom edge of the neritic zone, where sunlight does not reach the bottom. [3]

THREATS TO AQUATIC BIODIVERSITY Human activities are causing species to disappear at an alarming rate. Aquatic species are at a higher risk of extinction than mammals and birds. Runoff from agricultural and urban areas, the invasion of exotic species, and the creation of dams and water diversion have been identified as the greatest challenges to freshwater environments (Allan and Flecker 1993; Scientific American 1997). Overexploitation of aquatic organisms for various purposes is the greatest threat to marine environments, thus the need for sustainable exploitation has been identified by the Environmental Defence Fund as the key priority in preserving marine biodiversity. Other threats to aquatic biodiversity include urban development and resourcebased industries, such as mining and forestry that destroy or reduce natural habitats. In addition, air and water pollution, sedimentation and erosion, and climate change also pose threats to aquatic biodiversity.

Overexploitation of species — Overexploitation of species affects the loss of genetic diversity and the loss in the relative species abundance of both individual and /or groups of interacting species. The population size gets reduced because of disturbances in age structure and sex composition. Over-fishing causes change in the genetic structure of fish populations due to loss of some alleles. Thus, genetic diversity gets reduced.

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Habitat modification — Physical modification of habitat may lead to species extinction. This is mainly caused due to damming, deforestation, diversion of water for irrigation and conversion of marshy land and small water bodies for other purposes Pollution load — four forms of pollutants can be distinguished

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Poisonous pollutants — Agrochemicals, metals, acids and phenol cause mortality, if present in a high concentration and affect the reproductive functionality of fish (Kime, 1995). Suspended solids — it affects the respiratory processes and secretion of protective mucus making the fish susceptible to infection of various pathogens. Sewage and organic pollutants — they cause deoxygenation due to eutrophication causing mortality in fishes. Thermal pollution — it cause increase in ambient temperature and reduce dissolved oxygen concentration leading to death of some sensitive species. [20]

Global warming is causing sea levels to rise, threatening coastal population centres. Oil spills pollute the oceans, though U.S. water-sewage treatment plants discharge twice as much oil each year as tanker spills. Air pollution is responsible for almost one-third of the toxic contaminants and nutrients that enter coastal areas and oceans. [21]

CONSERVATION AND IMPROVEMENT Aquatic conservation strategies support sustainable development by protecting biological resources in ways that will preserve habitats and ecosystems. In order for biodiversity conservation to be effective, management measures must be broad based. 

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Aquatic areas that have been damaged or suffered habitat loss or degradation can be restored. Even species populations that have suffered a decline can be targeted for restoration (e.g., Pacific Northwest salmon populations). An aquatic bio- reserve is a defined space within a water body in which fishing is banned or other restrictions are placed in an effort to protect plants, animals, and habitats, ultimately conserving biodiversity. These bio-reserves can also be used for educational purposes, recreation, and tourism as well as potentially increasing fisheries yields by enhancing the declining fish populations. Avoid the establishment of industries, chemical plants and thermal power plants near the water resources as their discharge affect the ecology of water body resulted in loss of biodiversity. The World Resources Institute documents that the designation of a particular species as threatened or endangered has historically been the primary method of protecting the bio...