Marine biology
Specific habitats include estuaries, coral reefs, kelp forests, seagrass meadows, the surrounds of seamounts and thermal vents, tidepools, muddy, sandy and rocky bottoms, and the open ocean (pelagic) zone, where solid objects are rare and the surface of the water is the only visible boundary.
The organisms studied range from microscopic phytoplankton and zooplankton to huge cetaceans (whales) 25–32 meters (82–105 feet) in length.
Marine life is a vast resource, providing food, medicine, and raw materials, in addition to helping to support recreation and tourism all over the world.
Marine organisms contribute significantly to the oxygen cycle, and are involved in the regulation of the Earth's climate.
The human body of knowledge regarding the relationship between life in the sea and important cycles is rapidly growing, with new discoveries being made nearly every day.
[6][7][8] Biological oceanography also investigates the role of microbes in food webs, and how humans impact the ecosystems in the oceans.
Shore habitats span from the upper intertidal zones to the area where land vegetation takes prominence.
A subgroup of organisms in this habitat bores and grinds exposed rock through the process of bioerosion.Estuaries are also near shore and influenced by the tides.
An estuary is a partially enclosed coastal body of water with one or more rivers or streams flowing into it and with a free connection to the open sea.
They are subject both to marine influences—such as tides, waves, and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment.
Much attention in marine biology is focused on coral reefs and the El Niño weather phenomenon.
[14][15][16][17] The open ocean is relatively unproductive because of a lack of nutrients, yet because it is so vast, in total it produces the most primary productivity.
[20] In general, the deep sea is considered to start at the aphotic zone, the point where sunlight loses its power of transference through the water.
Hydrothermal vents along the mid-ocean ridge spreading centers act as oases, as do their opposites, cold seeps.
Microbes are responsible for virtually all photosynthesis that occurs in the ocean, as well as the cycling of carbon, nitrogen, phosphorus and other nutrients and trace elements.
Phytoplankton are categorized into cyanobacteria (also called blue-green algae/bacteria), various types of algae (red, green, brown, and yellow-green), diatoms, dinoflagellates, euglenoids, coccolithophorids, cryptomonads, chrysophytes, chlorophytes, prasinophytes, and silicoflagellates.
Plants that survive in the sea are often found in shallow waters, such as the seagrasses (examples of which are eelgrass, Zostera, and turtle grass, Thalassia).
The intertidal zone is also a good place to find plant life in the sea, where mangroves or cordgrass or beach grass might grow.
Most extant marine reptiles, except for some sea snakes, are oviparous and need to return to land to lay their eggs.
Through constant monitoring of the ocean, there have been discoveries of marine life which could be used to create remedies for certain diseases such as cancer and leukemia.
An active research topic in marine biology is to discover and map the life cycles of various species and where they spend their time.
Recent advances in underwater tracking devices are illuminating what we know about marine organisms that live at great ocean depths.
[38] The information that pop-up satellite archival tags gives aids in fishing closures for certain times of the year and the development of marine protected areas.
The study of marine biology dates to Aristotle (384–322 BC), who made many observations of life in the sea around Lesbos, laying the foundation for many future discoveries.
[41][42] The British naturalist Edward Forbes (1815–1854) is generally regarded as the founder of the science of marine biology.
Among the most significant were the voyages of HMS Beagle where Charles Darwin came up with his theories of evolution and on the formation of coral reefs.
[44] Another important expedition was undertaken by HMS Challenger, where findings were made of unexpectedly high species diversity among fauna stimulating much theorizing by population ecologists on how such varieties of life could be maintained in what was thought to be such a hostile environment.
[45] This era was important for the history of marine biology but naturalists were still limited in their studies because they lacked technology that would allow them to adequately examine species that lived in deep parts of the oceans.
[47] The development of technology such as sound navigation and ranging, scuba diving gear, submersibles and remotely operated vehicles allowed marine biologists to discover and explore life in deep oceans that was once thought to not exist.
