Microbes in the Ocean Microbes in the Ocean The oceans teem with microorganisms such as bacteria, viruses, and protists.
Marine waters cover two-thirds of the surface of the Earth. In some places the ocean is deeper than Mount Everest is high; for example, the Mariana Trench and the Tonga Trench in the western part of the Pacific Ocean reach depths in excess of 10, metres 32, feet.
Within this ocean habitat live a wide variety of organisms that have evolved in response to various features of Marine diatoms environs. Origins of marine life The Earth formed approximately 4. As it cooled, water in the atmosphere condensed and the Earth was pummeled with torrential rainswhich filled its great basins, forming seas.
The primeval atmosphere and waters harboured the inorganic components hydrogenmethaneammoniaand water. These substances are thought to have combined to form the first organic compounds when sparked by electrical discharges of lightning.
Some of the earliest known organisms are cyanobacteria formerly referred to as blue-green algae. Evidence of these early photosynthetic prokaryotes has been found in Australia in Precambrian marine sediments called stromatolites that are approximately 3 billion years old.
Although the diversity of life-forms observed in modern oceans did not appear until much later, during the Precambrian Marine diatoms 4. During the Cambrian Period about million to million years ago a major radiation of life occurred in the oceans. Fossils of familiar organisms such as cnidaria e.
The first fossil fishes are found in sediments from the Ordovician Period about million to million years ago. Changes in the physical conditions of the ocean that are thought to have occurred in the Precambrian—an increase in the concentration of oxygen in seawater and a buildup of the ozone layer that reduced dangerous ultraviolet radiation—may have facilitated the increase and dispersal of living things.
The marine environment Geography, oceanography, and topography The shape of the oceans and seas of the world has changed significantly throughout the past million years. According to the theory of plate tectonicsthe crust of the Earth is made up of many dynamic plates.
When two plates divergemagma from the mantle wells up and cools, forming new crust; when convergence occurs, one plate descends—i. Examples of both processes are observed in the marine environment.
Oceanic crust is created along oceanic ridges or rift areas, which are vast undersea mountain ranges such as the Mid-Atlantic Ridge. Excess crust is reabsorbed along subduction zoneswhich usually are marked by deep-sea trenches such as the Kuril Trench off the coast of Japan.
The shape of the ocean also is altered as sea levels change. During ice ages a higher proportion of the waters of the Earth is bound in the polar ice capsresulting in a relatively low sea level. When the polar ice caps melt during interglacial periods, the sea level rises.
These changes in sea level cause great changes in the distribution of marine environments such as coral reefs.
For example, during the last Pleistocene Ice Age the Great Barrier Reef did not exist as it does today; the continental shelf on which the reef now is found was above the high-tide mark. 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 lightwater depth, proximity to land, and topographic complexity all affect marine habitats. The availability of light affects which organisms can inhabit a certain area of a marine ecosystem. The greater the depth of the water, the less light can penetrate until below a certain depth there is no light whatsoever.
This area of inky darkness, which occupies the great bulk of the ocean, is called the aphotic zone. The illuminated region above it is called the photic zonewithin which are distinguished the euphotic and disphotic zones.
The euphotic zone is the layer closer to the surface that receives enough light for photosynthesis to occur. Beneath lies the disphotic zone, which is illuminated but so poorly that rates of respiration exceed those of photosynthesis.
The actual depth of these zones depends on local conditions of cloud cover, water turbidity, and ocean surface. In general, the euphotic zone can extend to depths of 80 to metres and the disphotic zone to depths of 80 to metres.
Marine organisms are particularly abundant in the photic zone, especially the euphotic portion; however, many organisms inhabit the aphotic zone and migrate vertically to the photic zone every night.
Other organisms, such as the tripod fish and some species of sea cucumbers and brittle stars, remain in darkness all their lives.
Marine environments can be characterized broadly as a water, or pelagic, environment and a bottom, or benthic, environment. Within the pelagic environment the waters are divided into the neritic province, which includes the water above the continental shelf, and the oceanic province, which includes all the open waters beyond the continental shelf.
The high nutrient levels of the neritic province—resulting from dissolved materials in riverine runoff—distinguish this province from the oceanic. The upper portion of both the neritic and oceanic waters—the epipelagic zone —is where photosynthesis occurs; it is roughly equivalent to the photic zone.
Below this zone lie the mesopelagicranging between and 1, metres, the bathypelagicfrom 1, to 4, metres, and the abyssalpelagicwhich encompasses the deepest parts of the oceans from 4, metres to the recesses of the deep-sea trenches.This web page will familiarize students with the Antarctic marine ecosystem.
Students will learn how physical conditions affect what kinds of plants and animals live here and how they interact with one another. Grade level: 7th thru 9th. This web page will familiarize students with the Antarctic marine ecosystem.
Students will learn how physical conditions affect what kinds of plants and animals live here and how they interact with one another. Grade level: 7th thru 9th.
Highlights Microplastics are emerging pollutants in the marine environment. This paper discusses the possible origins and the ecological impacts of these. They concentrate low-level pollutants in water. These become bioavailable via ingestion to marine organisms.
may turn sea water orange, yellow, brown, or purple. Red tides have been witnessed for centuries and have been seen all over the world. Dense concentrations of algae are referred to as blooms, because the algae have multiplied rapidly to become concentrated in high numbers.
Marine Phytoplankton's Powerful Micronutrients. Dr. Jerry Tennant, MD, from the Tennant Institute of Integrative Medicine, explains that the micronutrients and electrolytes in marine phytoplankton are exactly what human cell membranes need to carry out their metabolism.
Based in San Francisco, the Institute for Biodiversity Science and Sustainability is home to more than research scientists and nearly 46 million scientific specimens from around the world—38, of which are alive and on display in the Academy’s Steinhart Aquarium.