Ask a Marine Scientist:

answers to Oceanography questions!

Index To Questions
Underwater Sounds
Great Tides
Importance of Oceanography
What an Oceanographer Does
Ocean Facts
Why is the sea salty?
Salinity of the Atlantic Ocean
Measuring Salinity
Why do we have Oceans?
Ocean Origin
Mid Ocean Rift
Continental Shelf Marine Life
The Sulfur Cycle
Sulphate Transport
Artificial Sea Water
Marine Climate
Seasonality in the Seas
Ocean depth and limiting factors
Oeaanic Gas Hydrates
Different Types of Sediments
Difference Between Sea and Ocean
Depth of the Ocean
Ocean Depth
Depth Determination before Sonar
Pelagic Depth Zones
The Colour of the oceans
Secchi Disk
Measuring Turbidity
Wave formation
Wave Names
Tides & the Moon
When are tides the highest?
Outgoing Tide Term
Coriolis Effect
Bermuda Triangle
Atoll Formation
Green Flash
Scuba Equipment
Ocean Currents
Biggest Ocean
First Ocean Map
Deep water temperature and salinity
Volume of the oceans
Searching the Ocean
Settling an Ocean bet
Water Pressure
Ocean Mapping
Hot Water Volcanoes
The Coldest Spot
Tidal Erosion
Miscellaneous Cool Marine Facts
Varying Ocean Color
Dissolved Substances in Seawater
Ocean Color Variation
Different Beach Types
Undersea Diamond Mining
Accuracy of Ocean Mapping
Quantum metre

Underwater Sounds

Q: How do we know there is sound in the water if we can't hear it.

A: Scientists have been able to measure sounds that humans physically cannot hear. Some sounds in the oceans are in a frequency range that our ears cannot hear but they can be heard by scientific equipment. This is true for many low frequency sounds that our ears cannot detect.
However, there are many sounds in the oceans that we humans can hear. We can sometimes (if we are lucky) hear a humpback whale singing. We can also hear various sounds from Beluga whales, dolphins and so forth.


Great Tides

Q: What area on earth has the greatest tides? Why?

A: The area on Earth that has the highest tides is the Bay of Fundy in New Brunswick in Canada. This area has the highest tides because of resonance frequencies. Basically when the tide is coming in the wave frequencies keep piling on top of one another and the tide rises in this method.
A really simple explanation is what happens in a bathtub. When you slosh water around in a bathtub (provided you time it correctly) you can eventually slosh water right out of the tub. The tides in the Bay of Fundy are similar to what happens in the bathtub.


Importance of Oceanography - Received from Doug in Texas

Q: i need 3 reasons as to why oceanography is important and 3 specific jobs i could get if i majored in it in a university thank you

A. There are a variety of reasons why the science of oceanography is important. I'll give you three, since that is how many you asked for.

1. Knowledge - The more we know about the oceans, the better we will understand the geological and biological history and processes that operate on Earth. Oceanography helps us to understand our place in nature and the processes that led to the evolution of life on Earth.

2. Weather - By studying the earth's oceans we will be better equipped to predict patterns of water movement, heating, cooling and evaporative processes that directly affect weather systems. A better understanding of the oceans will enable us to forecast dangerous storms such as tornadoes and hurricanes.

3. Sustainability - Oceanography is probably most important simply because there are many unanswered questions about the oceans. The oceans are very important to people and all of the life forms that live on the Earth. A lot of our food, water and other important resources come directly or indirectly from the oceans. By having a better understanding of the ocean and the things that live there, we can learn to properly manage marine resources. Oceanography can help us to develop sustainable management plans for the marine organisms and products that we use on a regular basis.

There are lots of different types of jobs related to the field of oceanography. Here are a few:

Oceanographic Engineer - designs and builds equipment used by oceanographers and marine scientists

Plankton Biologist - studies the biology of the tiny organisms that float around in the ocean. Plankton are very important because they supply most of the atmospheric oxygen, and form the base of many marine food chains.

Deep Sea Biologist - study the animals that live in the deep sea. We don't know very much about the animals that live in the deep sea. The environment is unique, and a better understanding of the physiology, behaviour and ecology of the animals that live in the deep will help us to better understand evolutionary processes and the ocean environment.

There is lots more info on the Career Info page on the OceanLink website. I would check there for interviews with marine scientists and other stuff like that.



What Does an Oceanographer Do? - from Rachel in Illinois

Q: I'm doing a report on oceanography. Can you tell me what the definition of oceanography is and what specific things an oceanographer might do?

A: Oceanography is the scientific study of the ocean. Oceanography is a huge field and some of the areas of study include: ocean bottom geographic features (depths, volcanoes, trenches, oceanic plateaus, fracture zones, ridges and basins), plate tectonics, chemical composition of the ocean water (salt content, carbon dioxide levels, density, etc.), interaction between the ocean and the atmosphere (coriolis effect, weather systems, hurricanes, monsoons, cyclones, El Nino, etc.), ocean climates, ocean currents, waves, tides, chemical cycling in the ocean, plankton and sediments, just to name a few. I suggest you also check out the OceanLink website under the Career Info section you will find an interview with Dr. Louis A. Hobson, an oceanographer at the University of Victoria.



Ocean Facts - Received from L.Hensley in Greeneville, TN

Q: I am starting a new unit on Oceanography and Marine Biology for 4th grade students participating in a pullout program for certified intellectually gifted students. Research mentions 4 oceans, however several sources mention Antarctica Ocean and Southern Ocean. I asked my students to research this issue. Are there more than 4 oceans, are there 5?

A: There are four main oceans: the Pacific Ocean, Atlantic Ocean, Indian Ocean, and Arctic Ocean. The Antarctic Ocean or South Ocean is a smaller ocean that some books do not consider an ocean. But there are always difficulties when humans try to define boundaries on something that has no boundaries. Altogether there are five oceans, four major oceans and one smaller, the Antarctic Ocean.

1. Antarctic Ocean:
Numerous sources talk about the Southern Ocean and the Antarctic Ocean and they are the same area. The Southern or Antarctic Ocean is where the three main oceans meet (the Pacific, Atlantic and the Indian) at Antarctica (the continent). The Antarctic Ocean can be taken to include all oceanic areas lying south of the Antarctic Convergence, usually around latitude 55 degrees south.
Area: 13,513,000 sq. mi. or 35,000,000 sq. km
Area that is sea ice: 8,100,000 sq. mi. or 35,000,000 sq. km
Area that is permanently frozen: 1,540,000 sq. mi. or 4,000,000

2. Pacific Ocean:
The world's largest ocean, covering one third of the earth's surface.
Area: 64,000,000 sq. mi. or 166,000,000 sq. km
Average depth: 14,050 feet or 4,280 metres
Volume: 173,625,000 cubic mi. or 723,700,000 cubic km
Maximum depth: Mariana Trench - 36,161 feet or 11,022 metres

3. Atlantic Ocean:
This ocean is much smaller than the Pacific Ocean but has a drainage area that is four times larger than the Pacific.
Area: 3,166,000 sq. mi. or 82,000,000 sq. km
Average depth: 10,930 feet or 3,330 metres
Volume: 77,235,000 cubic mi. or 321,930,000 cubic km
Maximum depth: South Sandwich Trench - 30,000 feet or 9144 metres

4. Indian Ocean:
The world's third largest body of water and covers about twenty percent of the total world ocean area.
Area: 28,400,000 sq. mi. or 73,600,000 sq. km
Average depth: 12,760 feet or 3,890 metres
Volume: 70,086,000 cubic mi. or 292,131,000 sq. km
Maximum depth: Java Trench - 24,442 feet or 7,450 metres

5. Arctic Ocean:
The smallest major ocean (remember the Antarctic Ocean is not a major ocean). The area is slightly more than one sixth that of the Indian Ocean and it has a basin that is almost totally landlocked.
Area: 4,700,000 sq. mi. or 12,173,000 sq. km
Average depth: 3,250 feet or 990 metres
Maximum depth: Pole Abyssal Plain - 15,091 feet or 4,600 metres


"The Rand McNally Atlas of the Oceans" 1977, Rand McNally & Company, Chicago.



Q: Why is the sea salty? (Received from Caitlin in Los Angeles)

A: Thanks for your question. We've been waiting for someone to ask just this!
The salt that is in the ocean is actually comprised of a number of different chemicals that are dissolved in the water, and are called "ions". Six of these ions make up 99.36% of the weight of all of the ions in sea water. These ions are: Chloride (Cl-), Sodium (Na+), Sulfate(SO4--), magnesium(Mg++), calcium(Ca+) and potassium (K+). You'll notice that the two most common ions, sodium and chloride make up common table salt (NaCl) when put together.

But where did these ions come from? As the rivers move to the ocean, they dissolve the rocks that they pass over. Although this is a slow process, the rivers have been flowing for a very long time!. The dissolved ions in the water make their way to the ocean. When water evaporates from the ocean and falls on land as rain, the ions are left behind in the ocean.

Does this mean that the ocean is getting saltier and saltier? No!
It is believed that the oceans of the world are about as salty today as they were 1.5 billion years ago.

The ions are removed from the sea in a variety of ways. Calcium is removed by animals that deposit it in their shells. An arm of a sea can become isolated, and through evaporation, leave all of its salt behind (an examples are the salt flats in Utah). The most important way that the ions are removed from seawater is that ions can become "trapped" onto fine particles that then drift to the bottom of the ocean to become sediment. They are then not returned or redissolved into the seawater.

Hope this answered your question!



Salinity of the Atlantic Ocean - Received from Anneabeth in New Jersey.

Q: What is the salinity of the Atlantic ocean?

A: The salinity of the Atlantic Ocean varies according to depth and location. The highest salinity values are found in surface waters at 20-30 degrees north and south of the equator, where evaporation is high and precipitation is low. These values reach a maximum of 37.3 parts per thousand (ppt) in the Atlantic Ocean. The lowest salinity values are found towards the poles, where evaporation is low and freshwater inputs from melting ice and precipitation are high. The lowest salinity in the Atlantic is approximately 34.2 ppt in surface waters. Deep ocean waters are much less variable in salinity, since they are not subject to evaporation or direct freshwater inputs. Below 1000 m, the salinity is between 34.5 and 35.0 ppt at all latitudes.



Measuring Salinity - Received from Morgan

Q: Do you have anything on salinity testing?

A. There are many methods to measure salinity. Here are the most common methods:

1. Salinometer: this measures the true salinity of the water.

2. Ions: you measure the amount of ions in the water. The ions you measure are sodium(Na) and chloride(Cl) which are the two ions that make up sodium chloride (NaCl), salt. Other ions that can be measured are potassium(K), magnesium(Mg) and sometimes calcium(Ca). By measuring theses ions' concentrations you can get the approximate salinity.

3. Conductivity: you measure the electrical charge that passes through ions in the water. This method is the basis for the salinometer.

4. Refractometer: this method measures the refraction of light through a sample of water. The change in angle of the light changes as the salinity changes.



Why do we have oceans? - Received from Amber

Q: Why do we have oceans?

A: The reason why we have oceans is because we live on a planet that is largely water based. When the earth formed, water (or ice) made up a relatively large proportion of the matter that was present. As a result, we now have large oceans that cover almost 70% of the planet's surface. It is a good thing too, because all of the beautiful living creatures on the planet would not exist without water. The water in the oceans evaporates and the precipitation that is produced sustains almost all of the living things on Earth.



Ocean Origin - Received from Aaron Carter in Australia

Q: What were the origins of the oceans. How were they formed and what forces and reasons are involved in this process.

A: The Earth's oceans and atmosphere were formed from volcanic activity. During volcanic activity water and various gases are released from molten rocks that erupt from volcanoes. The water released from these processes are collected to ocean basins to form oceans. The Earth is large enough to retain water and atmospheric gases, so that it has both oceans, freshwater and an atmosphere.



Mid Ocean Rift (received from Arial in ???)
Q: What do scientists believe about the rift in the Mid-Ocean Ridg

A. We're not sure what you mean by what scientists "believe" about the rift, but we'll try to tell you what is know. The ridge system in the world's oceans is a series of great continuous underwater volcanic
mountain ranges that stretch for 65,000 km around the world, running through every major ocean. If you look at a map of the world ocean floor, you'll clearly see this ridge system. The ridges are caused by
the movement of the Earth's crust due to continental drift. As the continental plates drift, there are spreading zones where the crust is "pulling apart". These zones are areas of intense volcanic activity,
which creates the mountain systems. In the center of each ridge is a rift zone or rift valley. For example, Africa and South America are slowly moving apart. The crust is breaking and spreading in the area of the Mid-Atlantic Ridge. In the middle of the Mid-Atlantic Ridge is a rift valley, where the spreading is taking place. This rift valley is the site of many hydrothermal vents (see the OceanLink answers on this topic). The rift valley of the Mid Atlantic Ridge was first seen by people in 1973, when the submersible Archimede travelled to the site. In 1974, the submersible Alvin joined the study.



Continental Shelf Marine Life (received from Norman in Houston TX)|
Question: I am working on a school project on marine biology. Why is it that most life exists on the continental shelf

A. The continental shelf is a nearly flat land-border of varying width that slopes very gently toward the deep ocean basins. Shelf widths vary from a few meters to more than 100 kilometres. They average 65 km in width. At their seaward edge, the continental shelf is about 130 meters below the surface of the ocean. At this point, the continental slope drops off steeply to the ocean floor, which may be anywhere from 3000 to 6000 meters deep. Most life in the ocean is in the zone that receives sunlight, also called the photic zone (50 meters to 100 meters depth). This is because most marine life (with a few exceptions) is entirely dependent on sunlight for photosynthesis. The continental shelves are generally shallow, and have lots of plant and animal life. No light penetrates to the deep ocean floor, so no plant
life can occur there. Without plant life, the animals that live there are dependent on other sources of energy. Recently, scientists have discovered some very interesting animals that live in very deep areas
of the ocean. (see answers on hydrothermal vent animals). This shows that although a great deal of marine life is found in continental shelf areas, there are organisms in the deep sea - perhaps a few that have yet to be discovered!



The sulphur cycle - Received from Wendy in Waterloo, Ontario

Q: Could you tell me about the sulphur cycle and the relationship between the cycle and marine organisms?

A: If you've ever been to a poorly drained sandy beach or a mudflat, you couldn't help but notice the ripe egg smell from black deposits below the surface. These are caused by hydrogen sulphide, one of the products of the sulfur cycle.

When organic matter settles on the bottom, the sulphur-containing proteins are broken down into amino acids by specialized bacteria. These bacteria release sulphides or sulphates as by-products, which are then metabolized by other specialized bacteria, creating the sulphur cycle. This goes on all over the ocean, but in areas of poor drainage, these by-products accumulate in the mud or sand. These are called anoxic layers because they are devoid of oxygen. The only animals that can live in anoxic sediments are those that dig a tunnel to the surface to get fresh water.

In some special cases, like fjords, there is an under water ridge that only allows the relatively warm upper layer of sea water into the system. Because the water in the bottom of the fjord in cold, the new water stays above it and never mixes with it. Then you have a biologically rich layer in the middle and top of the water column, and a biologically dead anoxic zone in the lower water column (because the bottom is all sulphurous ooze.. In this way, the sulphur cycle can be detrimental to marine organisms, especially those that live on the bottom or feed on bottom dwelling organisms.



Sulphate Transport - Received from Jacki in Cleveland, OH

Q: Do you know of any papers or books discussing the transport of sulfates inland from the sea? My background is in geology and I currently am employed in the concrete industry.

A. I have never heard of sulfate transport inland from the sea. As far as I can recall, the transport of sulfates is predominantly in the direction from land to the oceans. Sulfates released into the atmosphere via combustion processes, emissions from industry dissolve in precipitation and are subsequently carried to the oceans in runoff. The only other sulfate (actually sulphide) sources I can think of are hydrothermal vent gasses. These are usually localized sources along volcanically active seabeds (i.e. the Juan de Fuca Ridge in the Pacific). However, I believe that the transport of these sulphides are limited to deep waters in the vicinity of the vents. I am unaware of any transport processes that parallel the one you have described. You may want to ask someone at the Woods Hole Oceanographic Institute or the Institute of Ocean Sciences in Syndey, BC. There are links to these resources through the OceanLink website.



Artificial Sea Water - Received Dec. from Erica in Indiana

Q: I need to know for a Science Fair project how to make sea water.

A: Here is the recipe for making artificial sea water. If you have access to these chemicals it is quite easy.

24.72 g NaCl
0.67 g KCl
1.36 g CaCl2·2H2O
4.66 g MgCl2·6H2O
6.29 g MgSO4·7H2O
0.18 g NaHCO3

Add dH2O to make 1 L

(Note: Add salts one at a time. Always add sodium bicarbonate last.)

Good luck with your Science Fair project.



Marine Climate (received from Tommy in Virginia)
Q: Hi! I need any info bout climates in the marine biome. In Charts or graphs! ANY MARINE BIOME!!!!!!!

A. If you check out our page of links to other marine sites you'll see a link to a site that gives ocean buoy data from around North America. In addition to recent data, this site also has data going back several months that you can download. Check it out!


Seasonality in the Seas - received from Linda in Coventry, Rhode Island.

Q: Does the sea have "seasons"? On land leaves fall in autumn. What are the signs of the seasons in the ocean? What happens during each? Where could I find out more about this?

A: Great question! There sure is seasonality in the seas. The seasons result from differences in temperature, nutrient levels, and light that change over the year.

Nutrients: In the winter, nutrients (particularly nitrogen and phospherous) increase in concentration in the highest layers of the water. This happens because of increased upwelling (the movement of nutrient-rich water from the deep parts of the ocean to the shallower parts), and storms, which generally increase water movement.

Light: Daylight is shorter in the winter, and the light is less intense, so it does not penetrate as far down into the water. The changes in light conditions are more dramatic in latitudes further from the equator.

Temperature: Water is warmer in the summer, and may be lower in salinity (salt concentration) because of freshwater run-off from the land.

These factors affect ocean life in varying ways. Primary productivity (plant-life growth) generally goes up during the winter because of the increase in nutrients. Some plants store these nutrients and don't start growing until the spring when there is more light. The seasonality of the plant life affects herbivorous animals in the ocean, which in turn affects all animals in the ocean foodweb.
As on land, seasons ocean productivity change more dramatically in polar regions of the earth than near the equator.
An example of the effects of ocean seasonality is the migration of large animals, such as whales. This happens because of the change in food productivity in different latitudes at different times.
The best way to find out more about this is to look at some books about ocean ecology, or primary productivity. An oceanography text book will have information about primary productivity and the seasonality of the oceans. Also, books about large migrating animals will have some information about seasonality.



Ocean depth and limiting factors (received from Steven in Mississippi)
Q. Does the ocean have a corresponding general depth to mountain height (i.e. 12,000 feet) sort of timberline in reverse? Mountain sickness and the timberline begins at 12,000 feet due to oxygen and temperature concerns, what about in the ocean?

A. Interesting question! I will deal with your question in two parts. First, lets look at marine life in the ocean. Whereas timberline is related to temperature and exposure, the major limiting factor for plants in the ocean is light. As visible light travels through water, the wavelengths begin to be absorbed. In the clearest of seas, red wavelengths (the shortest) will be eliminated within a few metres of the ocean's surface, while blue and indigo may travel to 200 metres depth or more. Plant growth is limited by the available light and which wavelengths of light can be utilized. Many red algae for instance, have accessory pigments that allow them to use blue wavelengths of light. Red algae therefore, are the deepest living plants in the ocean. Planktonic plants must remain fairly close to the ocean surface. So I suppose an equivalent "timberline in reverse in the ocean" could be around 200m or so (this depends on the clarity of the water). Beyond 200m, there are no plants and the animals there either eat other animals or eat detritus (feces, dead animals, etc.) or, as is the case with hydrothermal vent communities, have a food chain driven by bacteria and chemosynthesis, rather than photosynthesis. Since mountain sickness relates specifically to humans, I am assuming that you are interested in an equivalent sort of depth for humans in the ocean. (Marine animals have a variety of adaptations (depending on the organism) that allow them to cope with pressure changes). As you descend in the ocean, pressure increases by one atmosphere for every 10 metres of depth. As a diver descends, they must breath air that is at the same pressure as the surrounding water (e.g. trying to breath air through a hose to the surface just won't work!) The development of SCUBA (specifically a tank with compressed air and a pressure regulator in the mouthpiece) has allowed divers to breath air that is delivered at pressure equal to that surrounding them.

Divers can also becomes susceptible to the effects of dissolved nitrogen. At depth, a diver breathes pressurized air, and gases become dissolved in the blood and tissues. If a diver surfaces too fast, the dissolved nitrogen in the body tissues can come out of solution, forming potentially dangerous bubbles which may block blood vessels or may cause nerve damage. Nitrogen bubbles can also lodge in the joints, causing a painful condition know as the "bends". The problem of nitrogen bubbles is called decompression sickness and is treated by immediately evacuating the diver to the nearest recompression chamber. Here the patient is subjected to the same pressure as the deepest part of the dive, and is brought very gradually back to the surface pressure (1 atmosphere) as the diver breathes off excess nitrogen gas.

Physiological problems with humans in the ocean can occur at almost any depth, depending on length and depth of the dive, exertion, equipment, etc. however 30 metres is considered a reasonable depth for sport divers. Beyond this (and even before if the dives are long), divers must undertake decompression stops during their ascent.
Answered by Adrienne Mason


Ocean Depth - received from Rodney in Marion, South Carolina

Q: As far as we know, how deep is the ocean?

A: The ocean floor has an average depth of 4 km, or 13000 ft - but a lot of the ocean is deeper or shallower than that. In fact, the sea floor varies quite a bit in depth, with topographic features analogous to mountains and valleys on land.

Right off the edge of any continent is an area of relatively shallow ocean, called the "continental shelf". The floor depth here is no more than 150 m (500 ft) below water level.

After the shelf, the depth falls to somewhere between 3 and 5 km (10000 and 16000 ft). These are the abyssal plains, which are interrupted with hills and mountains where sediment has built up or submarine volcanoes exist.

Far out in the middle of the oceans, there is a belt of elevated floor called the "mid-oceanic ridge." The depth here is between 2 and 4 km (6500 and 13000 ft).

The deepest parts of the ocean are deep-sea trenches, which are elongated trenches that run along the edge of certain continental shelves. The depth here can be from 5 to 12 km (16000 to 40000 ft)

These formations exist because of a process called "continental drift." The earth's crust is made up of several plates that are slowly moving around; into and away from each other. The deep-sea trenches are areas where one plate is sliding down underneath another. The mid-oceanic ridges are areas where plates are moving away from each other, and hot magma (molten rock from below the crust) is rising to replace it.

The study of sea-floor topography is called bathymetry. You can find out more about bathymetry and continental drift in an oceanography or geology textbook. I found this information in "Invitation to Oceanography" by Paul Pinet, 1998.


Depth of the Ocean (received from Christopher in Missouri)
Q: What is the deepest ocean? How deep is it?

A. The deepest spot in all of the oceans is The Challenger Deep, located in the Mariana Trench, which is located between Japan and New Guinea. This spot is 11,035 meters deep (36204 ft or 6.89 miles), which can be compared to the height of Mount Everest at 8848 m (29028 ft or 5.53 miles).

Early mariners used a hemp line with a weight on it to measure depth. Later, piano wire with a cannonball attached to one end was used. This method was so time consuming (8-10 hours to winch the line up and down) that by 1895, only about 7000 depth measurements throughout the world's oceans had been made in water greater than 2000 meters. Today, information from depth recorders using sonar, as well as observation by submersibles has enabled us to make very detailed maps of the ocean floor. These maps may usually be found in any good world atlas.


Depth Determination before Sonar - received from Bill in Nantucket.

Q: How were depth determination made before the invention of sonar?

A: This is a really great question!

Before the invention of sonar, Early mariners made depth measurements, called "soundings", using a hemp rope marked in equal distances (usually "fathoms" which was the length of a person's fully outstretched hands, or 6 feet). With a lead ball on the end, the mariners would lower the rope until the tension in the rope changes, indicating that the lead ball had reached the bottom. If the covered the ball with grease before the let out the line, they could pick up sediment from the ocean's bottom (which would stick to the grease). This would be another indication that they had hit the bottom, as well as a way to sample what kind of terrain is underneath them.

This method worked fine for shallow waters, but in deeper waters it was too difficult to tell when the ball reached the bottom, because the hemp line was so heavy. Later, piano wire with a connonball attached to the end was used in deep water. The greater difference in weight between the line and the weight made it easier for mariners to tell when they hit bottom. The whole process was still rather difficult, however, taking 8 to ten hours for a measurement.

The invention of the echo sounder in the 1920s was great because it allows continuous depth measurements to be made easily and quickly as the boat moves. An echo sounder measures the time it takes for sound a pulse to leave the boat, reflect off the sea floor, and return to a hydrophone.

I found this information in an oceanography text book, called "An Introduction to the World's Oceans" by Duxbury and Duxbury, 1994.

The measurement of depth in the ocean in order to map out the ocean floor is called "bathymetry".

Thanks for the great question!



Pelagic depth zones - Received from Carrie in Massachusetts.

Q: I am teaching a 4th grade class and we are studying the layers of the ocean and the specific animals that live within each layer. If possible could you provide the specific depths that 10 animals live at (preferably animals from each layer). I greatly appreciate it.

A: It sounds like you're primarily interested in pelagic organisms which inhabit the water column, and not benthic organisms living on the sea bottom. The pelagic, oceanic environment can be broken up into at least five "layers" according to depth: epipelagic (0-200 m), mesopelagic (200-1000 m), bathypelagic (1000-4000 m), abyssopelagic (4000-6000 m) and hadalpelagic (6000-11000 m).

Here are some examples of different organisms living within each depth category:


1) Emiliania huxleyi - A species of coccolithophorid phytoplankton, E. huxleyi is present in all the oceans except the polar seas. Coccolithophorids are covered with many calcareous plates called coccoliths. After forming large blooms, these organisms die and accumulate in the sediment. Coccoliths are the major constituent of the white cliffs of Dover. For some great pictures of E. huxleyi, check out the Ehux web site.

2) Velella velella - Commonly known as the by-the-wind sailor, this small jellyfish (3 cm wide) has a sail which projects above the water surface to catch the wind.


3) Euphausia superba - Commonly known as krill, E. pacifica lives in the Antarctic Ocean and is the favourite food of baleen whales and crabeater seals. Even though krill make migrations into the epipelagic layer at night, they are considered mesopelagic because they reside in this zone during the day.

4) Vampyroteuthis infernalis - The vampire squid has jet-black skin, webbing between its arms and eyes that can appear red under some light conditions. Despite its name and appearance, however, the vampire squid is a very docile animal.


5) Caulophryne sp. - Female fanfin anglerfish have a "fishing pole" with an artificial lure projecting off the front of their head. This lure, which contains a light organ, attracts both prey and potential mates.

6) Eurypharynx pelecanoides - The gulper eel has a very large gape, weak jaws, tiny eyes and a soft body. It is thought to behave like a living net, engulfing prey (fishes and zooplankton) by swimming over them with its mouth open.


7) Cyema atrum - The snipe eel reaches depths of 5100 m.

8) Melanocetus sp. - The blackdevils are anglerfish which have been found to depths of 4790 m. The males are very small and exist primarily for reproduction. In many species, they live attached to the female.


9) Coryphaenoides sp. - This rattail fish was found between 6380-6450 m depth, and is characterized by a light organ on its stomach.

10) Abyssobrotula galatheae - This species of brotula was taken at 8370 m, and is the deepest-living fish known. It has a large mouth, tiny eyes and feeds on bottom-dwelling animals such as worms and isopods.

Its important to remember that the animals which live in each zone are not necessarily confined to that certain depth. These pelagic zones are human classifications based on depth, temperature and chemical/biological characteristics. There are many organisms which exist in more than one depth level, especially those that undertake migrations.

For pictures of deep-sea fishes, see the Sea and Sky Monsters of the Deep pages. For information about human exploration of the deep-sea, check out the Smithsonian page How Deep Can They Go?



The Colour of the oceans (received from Jonathan in New Jersey)

Q. Can you please give me some information about why the ocean appears in different colors in different parts of the world?
For example: What gives it a blue or green color. And is the Red Sea really red? If so why does it appear that way?

A. What a great question!
First, we need to talk about what colour actually is! You probably know that white light is composed of many different colours - you can see this when you see a rainbow. (Normal) white light is composed of many different "wavelengths", and each separate wavelength of light is a different colour. Long wavelengths of light are red in color, and short wavelengths are blue. When you see an object, and notice that is a particular colour, this is because the wavelengths of that colour are being reflected back to your eyes. For example, if you see a red ball, the shorter, blue wavelengths of light are being absorbed ("sucked up") by the ball, while the longer, red wavelengths of light are being reflected ("bounced back") into your eyes. Bet you never thought that physics and marine science were connected!!!

Now, back to the ocean. When you look into a large quantity of pure, clean water with no animals, plants or impurities in it, the water will absorb red wavelengths, leaving the blue and blue-green wavelengths to reflect back to your eyes. This is a natural property of water. The result is that pure water is not really clear - if you have a lot of it, at great depth, it will appear to be bluish. Of course, ocean water is not always pure. In coastal areas, there is often silt or other suspended solids in the water, especially near rivers. This will change the colour of the ocean water in these areas depending on the colour of the suspended solids. Also, there are often "blooms" of microscopic algae that occur in coastal waters, especially in temperate areas near the coast. These "blooms" are composed of billions of individual organisms, all of the same species. Each species has a particular colour, and the net result is ocean waters that may be reddish, brown, or even turquoise. A so-called "red tide" is composed of billions of organisms called dinoflagellates that actually colour the water red.
The Red Sea received its name because of dense blooms of an alga with large amounts of red pigment. The Gulf of California has been called the Vermilion sea for the same reason. So, the Red Sea really is red!



Secchi Disk - Received from Jane in Victoria, BC

Q: I recently visited Bamfield Marine Centre and I'm currently working on a project that related to my trip. One of the days we went out and measured the quantity of algae in Grapplers Inlet with a circular disc that was Black and White. I was wondering what this piece of equipment was called. Thank You very much

A.The device you used is called a Secchi Disk, and is used to measure light attenuation (the amount that is penetrating to water column). You used this as an estimate of the amount of algal growth in the photic zone from measurements of water clarity.


Measuring Turbidity - Received from Mia in Philadelphia

Q: What is the name of the instrument you measure turbidity with?

A: Turbidity is the reduction of water clarity due to suspended or dissolved materials in the water column. Some methods used to measure turbidity are as follows:

1. Secchi Disk: which is a flat circle-shaped disk painted black and white that is attached to a rope. A Secchi disk measures the depth at which light penetrates the water column. You measure light penetration, by dropping the disk into the water and when it disappears from eye sight that is the depth at which only 1% of the total light left that entered the water at the surface. The shorter the depth the more suspended particles, the higher the turbidity of the water is.

2. Some fancier equipment use optics that measure light between two distances and turbidity of the water can be determined by the amount of light present.

3. Using a conductivity equation is a common method for measuring turbidity. Conductivity is the amount of electrolytes (eg. NaCl, salt) in the water. If you measure conductivity and light you can calculate the turbidity in the water, because the amount of light that is not absorbed by electrolytes is absorbed by suspended particles.


Wave formation - Received from George in Hawai'i

Q: How do waves form by wind power?

A: When wind blows across calm water, it stretches it, causing wrinkles. The surface tension pulls back on the wrinkles to try and restore a smooth surface (like the recoil of a spring or elastic band). These two forces cause small waves on the surface called ripples. As these ripples make the surface of the water rough, there is more surface area and more bumps and ridges for the wind to "grip". This means more energy can be transferred from the wind to the water, which makes the waves bigger. If the wind is strong enough, large swells will eventually form.



Wave Names - Received from Yvonne Warren in Flemington New Jersey

Q: What is a low wave with a smooth crest called? What is a wave that forms a large curl called?

A: A smooth, long-crested, longer-period wave is called swell. Whereas when waves forms a large curl, the waves are losing their energy and are breaking, and these are called whitecaps.



Tides & the Moon - Received from Robby Vido in Denver, Colorado

Q: I want to know about what does the moons gravitational pull effect tide pools please explain!!

A: The tide moves in and out twice in a 24 hour period. When the tide is low that is when tidepools exist. Tidepools are areas, kind of like little pools in rocks (usually) that contain ocean water and a wide variety of marine life when the tide is low (out). The tides are controlled by the gravitational pull of both the sun and the moon, but the moon is the stronger force. Remember that the moon rotates around the earth and the earth rotates around the sun. The reason for this is that the sun's gravity is stronger than the earth's and the earth's gravity is stronger than the moon. The moon's gravity pulls on all parts of the earth, but it's pull is most strong on the side it is nearest to. The ocean is pulled out slightly by the moon's gravity on the side of the earth that the moon is closest to at that time. If you were to look at the earth from space, there would be a bulge sticking out of the earth on the side that the moon is on. There is also a bulge on the opposite side that the moon is at and this is because of the interaction between the earth and the moon creates another, equal sized bulge on the other side of the earth. These bulges are the earth's ocean being pulled towards the moon because of moon's gravity. The bulges are also where the tides are the highest and where the bulges are absent, that is where the tides are lowest. As the moon changes position, the bulges of the earth's ocean also moves along with with the moon. - see OceanLink's tides page!



When are tides the highest? (received from Scott at UBC)
Q: On what days of the year are the tides highest in this region?

We're assuming by your e-mail address that you're from Vancouver.
In general terms, there are two very high tide sequences per month - one during full moon and one during new moon. These are the times when the sun, moon and earth are aligned, and since the sun has an effect on the tides (46% of those associated with the moon), the tides are highest when both moon and sun are contributing to the tide. Tides during these periods are known as spring tides. Note that spring tides do not necessarily have to happen only in the spring months! They actually happen twice per month. The times when the moon is located at right angles to the sun and earth produce low amplitude tides known as neap tides.

In addition, the moon's orbit is not perfectly circular - it is elliptical. This means that there are times when the moon is closer to the earth (perigee) and further away from the earth (apogee). When a spring tide coincides with a time when the moon at perigee, very high and low tides occur. In the Vancouver region, this occurred around January 20-22, 1996, (16.4 feet high tide) and will occur again around Dec 12-14, 1996 (16.3 feet high tide).

If you are interested in accurate tidal predictions, you should purchase a copy of the Canadian Tide and Current Tables 1996, available at many bookstores (probably at the UBC bookstore!).



Outgoing Tide Term (received from Michael in New York)
Q: What is the is the term used for when the tide goes out

A. This is a pretty straightforward question!. An oceanographer or marine biologist would say that the tide was ebbing.



Coriolis Effect

Q: Can you explain the Coriolis Effect?

A: The rotation of the earth profoundly effects winds and currents. Humans do not experience the effects of the earth's rotation because we are bound to the earth's surface, whereas winds or currents move freely and are not bound to the surface of the earth. Wind and currents are deflected to the right of the motion (earth's rotation) in the Northern Hemisphere and to the left in the Southern Hemisphere. This deflection occurs because the wind and currents are on a rotating surface. This effect is called the Coriolis effect. If you are still confused, that's okay it's a confusing concept. Let me example using another explain. If you are standing in the centre of a giant turntable, that is NOT moving and you through a snowball at the a target attached to the side of the turntable, the snowball will follow a straight line and hit the target. However, let's rotate the turntable and attached target counter-clockwise. So now you are standing the centre of turntable that is rotating counterclock-wise, like how it would be if you were standing on the North Pole. Now if you throw the snowball at a target directly in front of you it will not hit the target but will be apparently deflected to the right. The snowball actually travelled in a straight line, but because the target moved when the snowball was is flight it appears to be deflected to the right. To imagine being on the South Pole, merely rotate the turntable clockwise and if you through a snowball now, the apparent deflection would be to the left.



Bermuda Triangle - Received from Zac in Ohio

Q: What is the Bermuda Triangle?

A: The Bermuda Triangle is an area located in the North Atlantic Ocean, near the Gulf Stream, where more than 50 boats and 20 airplanes have disappeared. It is a triangular shaped area located roughly between latitude, 25 to 40 degrees north and longitude, 55 to 85 degrees west and covers around 3,900,000 square kilometres (1,500,000 square miles). Since the mid-19th century records of many unexplained occurrences have been reported. Many ships have been found abandoned for no apparent reason and others have sent distress signals and were never heard from again. However, many planes and boats travel through this area and nothing out the ordinary occurs. There are various theories that attempt to explain the occurrences in the Bermuda Triangle. One theory is that waves may interact with currents, winds and other waves to form rogue waves. Rogue waves can be enormous enough to break up and sink large ships. But, no theory has been agreed upon, and perhaps more than one theory applies to the Bermuda Triangle.



Atoll Formation - Received from Quynh Son in Phoenix, Arizona

Q: How do you describe the formation of an Atoll?

A: An atoll is a modified ring-shaped reef that rise out of very deep water, far from land and enclose a lagoon in the centre. Atolls are found mainly in the Indo-Pacific area. There are many theories as to how atolls form, but one theory stands out above the rest: the subsidence or compensation theory.

The subsidence or compensation theory was first described by Charles Darwin after his five year journey on the Beagle (a boat). The theory goes that fringing reefs (a reef near a land mass) grow on the shores of newly formed volcanic islands. Volcanic islands are islands that were pushed to surface from deep water. These islands often begin to sink (subside), and if the sinking is not too fast, reef growth can keep up with the sinking, forming next a barrier reef and finally an atoll when island finally disappears under the ocean surface. When the island disappears corals will continue to grow and keep the reef at the surface. On the inside (remember atolls have a central lagoon), where the island used to be, quiet water conditions and high levels of sediments now exist there. These conditions in the centre prevent fast coral growth and that is how the lagoon is formed.


Green Flash

Q: What is "green flash"?

A: I found some info on green flashes! I hope it's not too late. Here's a great site that you should check out:
It has links to photos, descriptions and explanations on all sorts of webpages.

Here's a quick description, but definitely check out that site:
Green flashes are real (not illusory) phenomena seen at sunrise and sunset, when some part of the Sun suddenly changes colour (at sunset, from red or orange to green or blue). The word "flash" refers to the sudden appearance and brief duration of this green colour, which usually lasts only a second or two at moderate latitudes.


Ocean Currents - received from Samantha Day in Hornell, New York.

Q: How do ocean currents form in the ocean? I am working on a school project and need help with this question?

A: The water in the ocean is always in motion. It circulates around the world being pushed by powerful currents like the Gulf Stream as well as small eddies. The large currents are ultimately driven by the sun's energy. As water is heated and cooled, and evaporation and freshwater input levels (from rivers) fluctuate, the density of water will change. Warm, salty water is less dense and floats on top of less salty, colder water. This layering of the ocean will create a global ocean "conveyor belt". Deep water moves in one direction and warm surface currents move in the opposite direction and water is circulated around the globe in this way.

For a really great description of ocean currents check out this site at the Ocean Planet website


Biggest Ocean- received from Kalusa in South Carolina

Q: What is the biggest ocean?

A: The world's biggest ocean is the Pacific Ocean. The Pacific has a larger surface area , a larger volume and a greater average depth than either the Atlantic or the Indian Oceans. At the surface, the Pacific has an area of 179 700 000 km2 and a volume of 723 700 000 km3, with an average depth of 4028 m.

This info came from:
Introduction to the World's Oceans by Duxbury and Duxbury.


First Ocean Map - received from Amanda in Florida

Q: Do you know who was the first person to draw an ocean map?

A: This is not an easy question to answer... Many people attempted to map the oceans, but their attempts weren't truly accurate, and many of the historical maps have been lost. Here are some important early oceanographers:

-the Astronomer Pytheas (4th century BCE): map of Atlantic ocean
-Ptolemy: mapped the Indian ocean as an enclosed sea
-Columbus, Vasco de Gama, and Magellan (1492-1522): great geographical discoveries of oceans and continents
-Magellan mapped some of the ocean floor
-James Cook: discovered the continent of Australia, and many Pacific islands, clarified inaccuracies in previous mappings

You can find more in depth descriptions of explorations and discoveries in many books on Early Oceanography, or Historical Oceanography. One that I found particularly interesting is called "Founders of Oceanography" by Sir William Herdman written in 1923.


Deepest water temperature and salinity - received from Erin in Clarksville, Tn.

Q: Whar is the relative temperature and salinity at the deepest part of the ocean?

A: The deepest part of the ocean is called the Challenger Deep, part of the Mariana Trench, located southeast of Japan. This trench reaches a depth of 11035 m (36204 ft), which can be compared to the height of Mount Everest at 8848 m (29028 ft). The temperature in the Mariana trench ranges from 1.2-1.6 degrees Celsius and the salinity is around 36ppt (parts per thousand).
What is amazing about the Challenger Deep is that people have only ever gone down to 10900m. WOW!


Volume of the oceans - received on from Stephen in Benicia

Q: What is the volume of the oceans?

A: The volume of the oceans put together is 1 370 300 000 km3. That is a whole lot of water!


Searching the Ocean - received on from Kayla in Wisconsin

Q: How do you search the ocean?

A: That's an interesting question. I guess it depends on what you are searching the ocean for. If you are looking for surface dwelling creatures such as whales the fastest way to survey the ocean is aerially. Reserachers will often conduct aerial transect surveys to count whale populations. This is when the researcher is in a helicopter or small plane and they fly in straight lines a set distance apart and observe what they see directly below them. Transect surveys can also be done in boats, only they look to either side of the straight line the boat travels. Transects are a good way to save time because it would take you forever to look at every single place in the ocean, it is simply too big. If you are looking for fish or underwater creatures, you would probably use radar or sonar from a boat and then scuba diving once you've narrowed your search to a particular area. There is also the possibility of using submarines or remote submersibles to look for things in the ocean. If you are looking for underwater geograhical features or sunken ships, you would probably use sonar and then submersibles. New technology such as side scan sonar helps in underwater detection too (this is called Bathymetrics: surveying the seafloor).


Settling an Ocean bet - recieved from Lisa in Arizona

Q: My friends and I have a bet going... A few of us remember being taught that there were five oceans, but others say there are only four. Looking at atlases and in textbooks I realized that my other friends were right and there are only four. Is it possible that there USED to be five oceans and for some reason one got re-classified or got grouped with another ocean? Is there a reason so many people seem to think there are five oceans?

A: The terms and geographic boundaries used in modern Oceanography are always up for personal interpretation. The five oceans I assume you are referring to are;
the Pacific, Atlantic, Indian, Arctic and Antarctic. A while back, there has been a move in oceanography to consider the Antarctic Ocean just offshoots of the Southern Pacific, Atlantic and Indian Oceans. Likewise, there are some textbooks that will only refer to 3 oceans because they consider the Arctic as an extension of the North Atlantic. So, basically where you want to draw the lines between the oceans is up to you. It is hard to draw straight lines in so much water and they are all connected anyway!


Water Pressure - received from Micheal in Illinois

Q: Why is there so much pressure in water?

A: The pressure that occurs in water is actually the result of the mass of water. "Pressure" is a term that is used to relate the mass of something to the effect that it has on something else. In the case of water, the mass of the water has an effect on the organisms that live in it. Imagine for a moment that you are going to go swimming in a pool. At the surface of the pool, before you get in, you don't feel any pressure from the water, because you're body doesn't feel any of the water's mass. If you get in and dunk your head one meter below, your ears might pop because you feel the mass of the water above your head. This is pressure. If you then decide to go 2 meters below water, you have twice as much water (and therefore twice the mass) above your head as you had when you were only one meter below. You will also feel more pressure. If you go 10 meters below water, or more, your body will feel all the mass above you in the form of pressure. The reason that this is a concern in water and in organisms that live in water is that this pressure affects the gases in our bodies, such as that in our lungs and in our ears. When the pressure at large depths becomes too great, our bodies have a difficult time adjusting to the change.


Ocean mapping - received on from Lance in Texas

Q: I'm doing a project in school on ocean mapping. I would like any info. that you can give me.

A: Techniques for mapping the ocean floor have changed quite a bit over the years. In the late 1800's, oceanographers dangled weighted lines over the edge of the boat, in order to determine how deep the water was. In the 1920's, scientists learned to used echo sounders to map the ocean floor. Pulses of sound were sent into the ocean, and then the reflected signals were picked up by boats or submarines. The size (diameter) of the reflected echo relates to the depth of the ocean in that area. By the 1950's, the sounders were accurate to within 2m, and by the 1960's there was enough data collected to make a topographic map of the ocean floor. In the 1990's, the use of SONAR (SOund NAvigation Ranging) became common for mapping. A echo sounder is towed behind the vessel and sounds out narrow sound waves, which reflect off of objects in the water.


Hot water volcanoes - received on from Diane in Minnesota

Q: I am looking for information about hot-water holes or volcanoes.

A: This question first requires a little bit of background:

The Earth is divided into three layers: the crust (6-70km deep), the mantle, and the core. The crust is divided into 12 different plates (like a giant jig-saw puzzle!). As you go deep into the Earth, the temperature starts to increase. As a result, the mantle is actually fluid, and flows underneath the Earth's crust. As the mantle moves, the plates move with it. Where the plates are formed, a ridge is created (Mid Atlantic Ridge) and where the plates collide, one plate slides under another. The deepest spot in the ocean, the Mariana Trench, is 11km deep and occurs where the Pacific and Eurasia plates collide.

In the late 1970's a deep ocean submersible, called the Alvin, descended to the Mid Atlantic Ridge. Scientists were amazed to find a series of underwater volcanoes spewing hot water. These "smoking chimneys" emmitted high concentrations of various metals and dissolved sulphide. Surrounding these vents were diverse communities of tube worms, crustaceans, bacteria and fish. The first hydrothermal vent community was discovered!

If you are interested in finding out more, try doing a web search using "hydrothermal vents". Here is a couple of sites to get you started:
Dive and Discover's Hydrothermal Vent page - see cool photos of vent animals!


The coldest spot - received from Cassidy in Idaho

Q: How cold is it in the coldest spot? Where is it?

A: In the ocean, temperature decreases with increased depth. This is because light has a difficult time penetrating the water. At the deepest places in the ocean, temperatures reach near freezing (1.2-1.6oC).


Tidal errosion - received on from Michael in England

Q: I need to find out about coastal defenses to stop buildings falling into the sea due to tidal erosion.

A: Coastal errosion can occur for many reasons. Some natural forms of errosion occur due to wave action and rising water levels (due to global warming, so maybe it's not really natural!). Humans also contribute quite often to errosion due to the building of different structures such as dams (prevents sedimentation from travelling down a river), building close to the coast, removing trees, building groins, jetties, and breakwaters (designed to form protected bays and to reduce wave action and errosion, but often end up causing errosion further down the coast by preventing the movement of sediment). Statistics state that 40% of American shores are receiving less sedimentation than they lose. Errosion problems are very difficult to fix, and very costly. Some solutions are transporting sediment from other regions, or shunting sediment from one side of a breakwater to the coast on the other side. Unfortunately, I am not an engineer and I am not familiar with specific building structures used to prevent errosion. I suggest contacting an engineering department at your local university to see if someone there can help you further. Here are a couple of websites that maybe useful as well:

Centre for Coastal Studies, University of California, San Diego
USGS Coastal and Marine Geology Program


Miscellaneous cool marine facts - received from Ranger Rick Magazine

Q: A. About how many gallons of water can a pelican scoop up in its bill?
B. How many minutes can a sperm whale hold its breath underwater?
C. How many eggs can an ocean sunfish lay at one time?
D. How many bones are in a shark's body?
E. About how many suckers does a common octopus have?
F. About how many miles per hour can a sailfish swim?
G. How many inches long is an adult pygmy shark?

A: A. 17 pints (2.55 gallons)
B. 90 minutes
C. 300 million eggs - a world record!
D. 0 - a shark's skeleton is made of cartilege!
E. 8 arms, with 240 suckers on each arm = 1920 suckers
F. 68.18 mph
G. Between 7-10"


Varying Ocean Color

Q: Why is the ocean color different from Florida to Virginia? My 11 year old nephew wants to know.

A: Your nephew sounds very inquisitive. From the information i gathered the different ocean colors are a result of different levels of a tiny organism called phytoplankton. Sea color where there are lots of phytoplankton will be a greenish/blue while sea color in areas of lower phtyoplankton density will be dark blue nearly black. Its pretty amazing that an organism the size of a phtyoplankton (you need a microscope to see them) can change the sea color. A second way for oceanic color change to occur is related to sand color. An shallower ocean with a whitish sand bottom will appear a lighter blue than one with a darker sand bottom.
Thanks for the great question.


Dissolved Substances in Seawater

Q: Why can you find traces of all naturally occurring substances in seawater and why do these concentrations differ from rivers to the ocean?

A: To answer your first question water can dissolve or be a transport medium to virtually any dissolved substance on the planet. The dissolved substances eventually reach the ocean. The industrial processes allow for much more dissolved substances to reach the ocean such as heavy metals metals (Eg mercury) and so forth. The ocean is also a dumping ground for potentially thousands of man-made chemicals as well.
To answer your second question concentrations of dissolved substances are higher in a river than they are in the ocean. When dissolved substances in a river meet the ocean they are diffused into a much larger body of water this lowering the concentration of the substance. A simple explanation is to take a glass of salt water and pour it into a full bathtub. The bathtub water has the same amount of saltwater that was in the glass but its over a larger area thus lowering the concentration of salt.


Ocean Color Variation

Q: Why are the tropical oceans a lighter blue color while the temperate oceans are a much darker blue?

A: From the information i gathered the different ocean colors are a result of different levels of a tiny organism called phytoplankton. Sea color where there are lots of phytoplankton will be a greenish/blue while sea color in areas of lower phtyoplankton density will be dark blue nearly black. Its pretty amazing that an organism the size of a phtyoplankton (you need a microscope to see them) can change the sea color.
The second way that the ocean can have a different color is dependent on the color of the sand on the ocean floor. This is only for areas that are relatively shallow however. If in a shallow area the bottom has white sand the ocean color will be a light blue to a pale blue green.


Oeaanic Gas Hydrates

Q: What exactly are oceanic gas hydrates and much reserves are there in the world? I heard that the BBC (British Broadcasting Company) stated that has hydrates represent 80000 times the existing natural gas reserves.

A: I did not have a clue that these deposits of hydrates existed at all. Gas hydrates are balls of frozen methane on the ocean floor. They occur at very deep depths. I am pretty sure that the BBC was being truthful when they stated that hydrates could represent 80000 times the natural gas reserves. The United States geological survey estimates that the hydrates off the coast of North Carolina alone represent 350 times the total use of energy in the U.S. in a given year. This represents an incredible source of energy. However its very expensive and dangerous to extract them from the ocean floor. It may be possible later in this century and into the next one to extract these reserves but it will not occur until we have exhausted present reserves or cost of present extraction is to high. There are also existing large oil reserves that we can extract such as the tar sands and so forth.


Scuba Equipment

Q: Is there Scuba diving equipment for overweight people?

A: Most scuba diving equipment stores will sell custom fitted scuba gear. The only downfall of custom fitted gear is that it will cost more. However it will be worth it in the long run if it fits better.


Different Beach Types

Q: Whe are beaches different in some parts of the world?

A: A lot of the time the beach type is determined by materials that are readily available for beach formation. In this way a very rocky shore may have a rocky beach. If the near beach materials are sandy the beach will likely be sandy as well. An example is beach development where beaches are formed by the weathering of valcanic lava flows. These beaches usually have very black sand. In other cases longshore drift of sand materials can create sandy beaches. In areas where longshore drift is altered by development (such as harbor development) the beaches can be altered to the point where a new sandy beach may develop in place of an older one.


Different Types of Sediments

Q: What are the different types of sediments on the ocean floor?

A: There are five different types of major sediment groupings. I will go over each of then in turn.
1. Terrigenous or land based sediments. These sediments are from the weathering and erosion of land based rocks and minerals.
2. Biogenic sediments. These sediments are from the decay of things such as animal skeletons, shellfish shells and animal teeth.
3. Cosmogenous sediments. These sediments are from debris from outer space and the rarest of all Earth's sediments.
4. Hydrogenous sediments. These sediments are from chemical and biochemical reactions on the ocean floor. An example is manganese nodules on the ocean floor.
5. Volcanogenic Sediments. These sediments are from volcanic ash fallout and so forth.


Undersea Diamond Mining

Q: Since there is vast amounts of oil reserves in the ocean basins I was wondering if there were diamond reserves as well. Is it possible for undersea diamond mining to occur if there are diamonds on the ocean floor?

A: I have done some research and was surprised with what I found. Diamond mining is actually taking place right now in the oceans along the African Coast (namely around Namibia) to depths of around 600-700 feet. These diamonds appear to have been deposited thousands of years before. According to an article that I read the technology is improving rapidly and there will be some expansion in the near future. further information indicated that this type of undersea mining has been going on since the 1960's but a lack of sophisticated technology made the work costly and difficult to manage. If you can find diamonds in the ocean it makes you wonder what else you can get from down there doesn't it?
Hope I answered the question. This news story will give further information regarding minerals on the ocean floor.


Difference Between Sea and Ocean

Q: What is the difference between a Sea and an Ocean and why the distinction?

A: Seas are just extensions of an ocean. For the most part seas are indentations of the larger ocean body into a continent. Seas can be partially or totally landlocked. An example of a large sea is the Mediterranean which is an extention of the Atlantic Ocean. The Mediterranean is fairly landlocked with major choke points at the Straits of Gibraltar (entrace off the coast of Spain) and the Dardanelles (exit to the Black Sea). Sometimes seas can be totally landlocked within a continent such as the Caspian Sea in the middle of the old Soviet Union. Landlocked seas have salt-water. The worlds largest lakes are not seas because they have freshwater instead of saltwater.

A sea becomes an ocean when its not confined by the land masses. For example when the Mediterranean exits into open water it becomes the Atlantic Ocean.


Ocean Maps Getting More Accurate?

Q: Why does an oceanographer's map of the ocean floor get more accurate as more sonar reading are taken?

A: Well there a few reasons why maps of the ocean floor keep getting better. First off sonar keeps improving and scientists can get a more accurate reading of the ocean bottom. Secondly many of the older maps were made with older sonar systems that were not as accurate as todays. In some areas there may not even be accurate sonar data at all. Also the ocean bottom can change in an area over time with new sediments added, sediments that shift from ocean currents or underwater earthquakes and so forth. As time progresses however the date just keeps getting better. The unfortunate part of it all is that getting sonar data is expensive so updating charts can take a long time to occur.

Quantum Metre

Q: What is a quatum meter? What is a Salinometer?

A: A quantum meter is designed to analyze PAR (Photosynthetically Available Radiation). Basically the quantum meter analyzes the amount of light energy that a plant can use to create usable energy. The salinometer is an instrument (on the principle of a float) for measuring the degree of salinity or the concentration of the brine or seawater.


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