Ask a Marine Scientist:
answers to Plants and Algae questions!
Index To Questions
 Phytoplankton
and Earth's Oxygen - Received from Brendan in Duncan,
BC
Q: Hello, My name is
Brendan Newbury. I was at your marine station on Nov.9 to
Nov.11 with the Duncan Christian school biology trip. We
now have to do a big poster on habitat loss. We also have
to do a poster on the fact that the ocean creates 90% of
earths oxygen. I was wondering how the oxygen from the ocean
gets to the land. I was also wondering which plants are the
largest producer of oxygen. What are the most common causes
of habitat loss in the ocean? Could you please tell me where
some of the major habitat losses are and why this is happening?
A: In the ocean, oxygen
is produced as a byproduct of photosynthesis by phytoplankton
(single celled sea plants) and algae (multicelled sea plants).
Although individual alga are much larger than plankton, the
latter have a staggeringly larger biomass and so produce the
most oxygen. Considering the Earth is more than 70% water and
phytoplankton are found throughout the ocean, it's not surprising
that they make up 90% of the Earth's oxygen production.
The oxygen produced by phytoplankton
is released as a gas. Some of this is absorbed back into the
ocean, but most flows into the atmosphere. From there it becomes
available for use by all oxygen breathing organisms.
Some common causes of habitat
loss in the oceans are oil spills, industrial and residential
waste, overzealous ecotourists, and exotic species introduction.
Most habitat loss takes place around port cities or any area
with high human traffic. Most people don't understand how delicate
marine systems are. The damage to or removal of a single species,
even if they aren't the most abundant, can devastate an area.
A good example is the removal of sea otters from the kelp forests
off California. Without otters to prey upon them, sea urchin
populations skyrocketed. Since they feed on kelp, the kelp
forests were decimated and turned into a wasteland. All the
other organisms
that relied on the kelp for food, protection, or habitat either died out or
left the area. For other examples, check out the Greenpeace or the World Wildlife
Fund.
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Average
Concentration of Plankton - Received from Barbie
in New York
Q:
What is an average concentration, in cubic litres, of plankton
in the ocean?
By average, I mean near-coastal waters not necessarily undergoing
a bloom. Is there a "general" or average ratio
of phyto- to zooplankton in this hypothetical average ocean
water? Could you also give me a range (blue water vs. upwelling/bloom)?
A. As
far as I know, there is no "average" value for the
concentration of phytoplankton in coastal or oceanic waters.
The distribution
of plankton in the oceans is very patchy and constantly in
flux, two reasons why there probably are no such values. Plankton
is highly seasonal, with a large bloom in the Spring followed
by a smaller one in the Fall (in the northern hemisphere) .
Furthermore, the concentration of plankton is also a function
of nutrient concentrations, water clarity and temperature,
which further complicate the synthesis of any generalized,
static values.
With the advent of satellite
imaging techniques, some crude measurements of phytoplankton productivity have
been made for various regions of the oceans. Productivity (<100
mg C/m2/day) are encountered in the convergent gyres, whereas
higher values (>250 mg C/m2/day)are found in the temperate
oceanic areas and the coastal zones. The coastal upwelling
regions have values of up to 1000 mg C/m2/day.
Please note that these are
approximated values for productivity, which is a measurement
of the amount of carbon incorporated into cellular material
per unit area of ocean per day. You may also see measurements
expressed as (mg Chl/litre/day) which is based on analysis
of chlorophyll-a (which is present in all algal cells) concentration
in samples of seawater.
Blue water (usually tropical
areas) is characterized by having very low concentrations of
suspended material and nutrients in the water. The subsequent
lack of phytoplankton cells in the water is one of the main
reasons why the water is so clear in those areas.
I'm not sure about specific
ratios, but I do know that there is considerably less biomass
as you go from one trophic level to another. At any given time
there is considerably more biomass (i.e. grams of carbon per
meter squared) in the phytoplankton than in the zooplankton.
Estimates of zooplankton abundance are complicated by a whole
series of additional factors. Zooplankton concentrations are
dependent directly on phytoplankton abundance but there are
behavioural and fluid dynamic considerations as well. Many
forms of zooplankton have the ability to swim, and many species
have daily cycles of migration up and downwards through the
water column. If you consider currents and other features of
water dynamics that affect the swimming motions and feeding
mechanisms of these animals (remember, they feed on the phytoplankton),
you begin to see that the measurements and equations for approximating
zooplankton concentrations are rather complex.
I hope that answers your
questions. If you have any more, let us know!
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Uses
for Seaweeds - Received from Justin in Oklahoma
Q: Could you please tell
me about how seaweed is used medical or any links to seaweed
 A.
Seaweed has many different uses in biology and medicine. Agar
is a substance that is used in the culture of bacteria and
other microorganisms. Petri plates are lined with agar gels
and incubated. Hospital laboratories frequency use agar plates
to identify types of infectious bacteria. Agar plates are also
used for other biological studies of fungi, bacteria and viruses.
Agarose is another substance that is extracted from seaweeds
and commonly used. Agarose gels are used in chromatography
to purify proteins, DNA and other substances.
Here is a website that describes
other uses of seaweeds
I hope this helps you out.
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Red
Algae - Received from Mr. Nurimba in Shanghai,
China
Q: What is Rhondophyceae
? also known as Chondrus crispus, c.Dceblatus,
Eucheuma cottonil, E-spinosum. Is it a type of sea weed ? I was told that they
are available in Indonesia and the Philippines. It is said that they can be
used commercially as a kind of syrup. Pls provide any info that you have. Many
thanks.
A: Rhodophyta is the division
name for red algae, where Rhodophyceae is the class name for
red algae. There are over 10,000 described species of red algae
found worldwide. The four species you listed the genus and
species names for are different types of red algae. I was able
to find information on Chondrus crispus, Eucheuma
cottonii and Eucheuma spinosum. However, I was unable
to find information on Chondrus dceblatus, perhaps it
has recently changed names, red algae have an extremely challenging
and always changing classification system.
Eucheuma is
a genus of tropical red seaweed that grows on limestone-rich
substrates, especially coral reefs. This seaweed is eaten in
China, Malaysia and other southeastern Asian countries. It
is also harvested for a raw material called carrageenan, which
is used as a thickener in many of today's food and dairy industries.
Carrageenan is the "syrup" substance you had asked
about.
Chondrus,
the irish moss, was the traditional red seaweed grown and harvested
for its carrageenan content. However, recently the carrageenan
industry have focused on more productive carrageenan producing
red algae, such as Eucheuma.
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Kelp
Reproduction - Received from George on Earth
Q: How does kelp reproduce?
A: Kelp
reproduction is much different from that of land plants. Kelp
undergoes something called alternation of generation. In this
example, I'll discuss the bull kelp Nereocystis. The
form of kelp that you are more likely to see is the large sporophyte
stage. This stage of the plant has a full complement of genetic
information (diploid), and produces spores called zoospores
with half of the genetic information (haploid), just like animal
sperm and eggs. A typical bull kelp can produce up to 3.5 trillion
zoospores in one year. These zoospores settle to the bottom
and grow into microscopic male and female haploid gametophytes.
The male gametophyte produces mobile sperm that seek out the
eggs that are kept on the female gametophyte. Once fertilized,
the zygote (the baby kelp with a full set of genetic material)
grows into the giant sporophyte and the cycle begins again.
The sporophyte stage only lives for one year, but considering
the number of zoospores they can produce, it's long enough.
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Largest
Seaweed - Received from Alex in California
Q: What is the largest
sea plant?
A: The largest seaweed in
the world is a brown algae (kelp) called Macrocystis pyrifera (the
giant kelp). The longest recorded length is 54 metres long! M.
pyrifera is the type of kelp that makes up the majority
of the giant kelp forests off the California coast.
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Red
Tide - Received from Tracy in Connecticut
Q: I would like some
information on paralytic shellfish poisoning. Specifically,
how it chemically interacts with human cells to cause it's
effects.
A: Paralytic shellfish poisoning
(PSP) is one of several toxic results of eating seafood contaminated
with certain phytoplankton. Others include diahretic and amnesic
shellfish poisoning. PSP is a danger when warm ocean and lots
of sunlight in mid to late summer cause
huge blooms of these organisms, so much so that they stain
the water red (hence "red
tide"). These phytoplankton can accumulate in and then infect the people
who eat them. The toxin interferes with human nerves, stopping signals from
travelling to and from the brain to control the bodies muscles. The symptoms
start with a light tingling in the extremities, which eventually progresses
until it paralyzes the diaphragm causing suffocation, or the heart causing
instant death. PSP is monitored by local coast guard and fisheries department,
who post warnings. Heed them. For more information, check out this Red Tide
site.
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Bioluminescence
- Received from Ann in Seattle
Q. What can you tell me about the phosphorescence that you see while paddling
or disturbing salt water at night. I was always told that it was caused by
a certain type of plankton.
A. "Phosphorescence" is
more correctly known as bioluminescence. This means
living (bio) light (luminescence). This is light that is biologically produced
and is caused when a light-emitting molecule, called luciferin, is mixed with
an enzyme, luciferase, in the presence of
oxygen. (The light produced in bioluminescence looks very similar to the light
produced when phosphorous is exposed to oxygen. Thus the common, but incorrect,
term phosphorescence).
Bioluminescence is actually quite common and almost all taxonomic groups of
animals, and many plants, have some members that bioluminesce. Planktonic dinoflagellates
and bacteria are some of the most abundant creators of this biological light
and are what is usually responsible for the green glow in a boat's wake or
when waves break on a beach. Other animals, including fish and squid, create
light by keeping small cultures of luminescent bacteria in specialized organs
distributed over their body. Since the bacteria bioluminesce continuously,
their hosts have developed mechanical means, such as flaps of skin that resemble
window shades, to control luminescence.
So why do these individuals
create light? Reasons for bioluminescence vary depending on
the organism, but they generally fall into one of four categories:
escaping predators, obtaining prey,
attraction, and advertising. Some organisms use the "quick flash" technique
to temporarily blind a predator"a familiar sensation as when faced with
an inexperienced photographer let loose with a
flash. Many bacteria actually luminesce because they want to be eaten. They
advertise to potential prey hoping to find a comfy home inside a fish's gut.
Answered by Adrienne Mason
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Photosynthesis
in seaweeds - Received from Jax in England
Q: How do seaweeds photosynthesize
underwater?
A: Seaweeds have a variety
of adaptations for carrying out photosynthesis under the water.
Terrestrial plants evolved from lineages that originated in
the ocean, so much of the fundamental photosynthetic machinery
originated among the alga. Unlike terrestrial plants, alga
do not have true vascular tissues. Since algae live underwater,
they are surrounded by water and nutrients. The algae absorb
water and nutrients directly from seawater. By maintaining
a high surface area to volume ratio (seaweeds are generally
flattened) the individual cells that make up the alga can absorb
the water and nutrients that they need directly.
The main materials required
for photosynthesis are carbon dioxide, water and sunlight.
Seaweeds absorb carbon dioxide that is dissolved in seawater.
CO2 is sometimes limiting in areas where there is low water
velocity or for species that are periodically exposed to air
during low tides. Water is not a limiting factor because these
organisms are immersed in it. Light is perhaps the predominant
limiting factor because with increasing depth, there is an
exponential decrease in light availability. Among seaweeds
there are a variety of morphological and physiological adaptations
for dealing with the problem of light availability.
Many seaweeds maintain their
photosynthetic blades near the surface where light intensity
is  maximal.
The bull kelp, Nereocystis leutkeana, has an inflated
bulb that floats at the surface. The meristem is located at
the base of the blades (fronds) which attach to this bulb.
With the chief photosynthetic organs at the surface, light
intensity and photosynthetic potential are maximized. There
are several other species that employ floats to lift the blades
to the surface. Macrocystis integrifolia and Egregia
menziesii are two species that also have floats.
With increasing depth, more
and more of the visible spectrum of light is filtered out by
the water, particularly in the red and blue regions of the
spectrum. As a result, many species of algae are limited to
shallow subtidal waters. Most green algae, Division Chlorophyta,
are restricted to the zone from a 5m depth to the surface.
Below this depth, their chlorophyll (which absorb mainly blue
and red light) and accessory pigments (carotenoids) are insufficient
for capturing the energetic wavelengths of light that are available.
The brown algae, Division Phaeophyta, and red algae, Division
Rhodophyta, can be found in deeper waters. These seaweeds have
additional accessory pigments that allow the plants to capture
a wider range of light energy thus enabling these organisms
to persist in areas with lower light availability. These accessory
pigments are known as phycobilins and absorb energy in the
green portion of the visible spectrum. The Rhodophytes can
be found deepest due to the presence of phycoerythrin, an accessory
pigment that absorbs very efficiently in the green portion
of the spectrum. In deep waters, green light is most abundant,
and therefore, only the seaweeds with the right combination
of pigments for tapping this wavelength can survive. Many of
the deeper rhodophytes appear to be black in colour when they
are observed during dives. Their dark colour can be attributed
to the high concentrations of phycoerythrin in the cells of
these seaweeds.
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Plant
Life in the Oceans (received from skydot(?!) in
New Hampshire)
Q: I have been wondering if plant life is part of marine biology
Yes, it certainly is, although most of the plant life in the oceans is very
different from most of the plants that you see growing on land.
If you go to the seashore, you'll probably see lots of seaweeds. These are
marine algae, and are very important in the food webs of shallow coastal marine
communities. The red, green and brown algae produce food by using photosynthesis
just like land plants do, except they do not have any specialised tissues for
transporting this food (ie, they have no "sap" or transport tissues).
Just as animals on land (consumers) depend on plants on land (producers), so
do marine animals depend on algae.
A common green algae is Ulva, or sea lettuce. Kelps are in the group
known as brown algae, and are especially important in coastal marine areas
on the West coast of North America.
Many marine biologists study marine algae, because it is of such great importance
to the marine ecosystem.
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Flora
and Fauna - Received from Samantha Aguilar in Dilley,
Texas
Q: What are fauna and
flora? Can you help us?
A. Flora
and fauna are basically just fancy names for plants and animals.
Specifically, flora is the word biologists use to describe
the plant life of a given region or habitat; and fauna is all
the animal life in a given region or habitat.
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Deep
Sea Plants - Received from Caitlin in the United
States
Q: Does the DEEP SEA
zone have any plants?
A: The deep sea is too deep
for light to penetrate that plants need to make their food.
Plants get their energy from sunlight and through a process
called photosynthesis, turn this sunlight into food for the
plant. Since there is not any usable light available for plants
to photosynthesize in the deep sea plants cannot live there.
There are bacteria that
can live as deep as 1500m to 3200m near deep sea hot vents.
These bacteria use a compound called hydrogen sulfide, instead
of sunlight, to make their food. The bacteria get the hydrogen
sulfide from deep sea hot water geysers that release this compound.
In fact, because of these tiny bacteria an entire community
of animals can survive and thrive in these hot vent areas!
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Seagrass
Epiphytes - Received from Ahmad Faizal in K.Terengganu,
Malaysia
Q: What is the importance
of epiphytes on seagrass bed?
A: Epiphytes of seagrass
are algae and other seaweeds and these epiphytes use the seagrass
merely for physical support. Epiphytes can be an important
food source for animals in and around seagrass beds. Animals
can also use the seagrass and epiphytes to hide in and therefore
protect them from predation or to stalk prey. However, epiphytes
are not necessarily beneficial to the seagrass. Epiphytes growing
on the seagrass cover the photosynthetic area of the seagrass
blade and therefore reduce the photosynthetic capabilities
of the seagrass. In fact, a problem in seagrass beds, in mainly
tropical systems, is fouling. Fouling occurs when there is
a rapid growth of epiphytes, usually diatoms, that completely
cover the entire seagrass blade. This coverage prevents the
seagrass from receiving sunlight and thereby inhibits photosynthesis
and the seagrass eventually dies. The rapid growth of epiphytes,
such as diatoms is usually the result of high nutrients. These
high nutrients levels are usually caused by human activities
in the area, such as fertilizers from agriculture.
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Seaweed
Adaptations - Received from Jennifer somewhere
out there
Q: In the sunlit layer
of the ocean, how do plants adapt? I only need 3 ways.
A: Algae (aquatic plants)
have many adaptations to living in the photic zone (sunlit
layer) of the ocean. One way is by having different types of
light catching pigments. For example, green algae have cholorphyll
a which absorbs mainly red and orange light. Whereas red algae
have accessory pigments, called phycoerthryn and phycocyanin
that absorb blue and violet light. Another way is by having
larger blade surface area, and therefore increasing the light
absorbing area of the algae. In the photic zone there is a
lot of competition for space between different algal species.
Some algal species have adapted different ways to push out
other species. For example, a brown algae called the Feather
Boa (Egregia) actually whips the other algal species
out of the space surrounding it.
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Seaweed
Starches - Received from Emily Alderson in Sidney,
BC, Canada
Q: my name is Emily and
I'm in grade 8.I am working on a science fair project for
the Uvic regional science fair and I have a few questions.
my project is on the nutritional values of common seaweeds.
Could you please tell me if there is usually starch in seaweed.
I did a test [using iodine] but nothing happened. If so,
what types of starch, and also what,m if any, types of sugars.
How could I find out if the water at the beach where I got
the seaweed is polluted? It is too expensive to take it to
a water analysis lab. i also dried the seaweeds in my experiment
to see what percentage of them were made up of water. Would
there be any other substances in the seaweed which could
have dried up affecting my results? Thank you very much for
reading my questions.
A: Wow it sounds like you
have quite the project! First the reaction to your iodine test
will depend on what kind of seaweed you tested. There are three
types of seaweed red, green and brown. All three types of seaweed
have storage polysaccharides (sugars) in them, and it is the
glucose polymers (a type of polysaccharide, sugar) that are
most similar to the starch of land plants. The kinds of glucose
polymers change depending on the group of algae you are looking
at. The similarity to the starches of land plants is greatest
in the green algae, less in the red, and least in the brown.
In the green algae (Chlorophyta), there are polysaccharides
that are stored in granular form that react to with iodine
to give a blue-black colour. Because of this reaction it appears
that the polysaccharides in the green algae are similar in
structure to the starches found in land plants. Red algae (Rhodophyta)
have floridean starch which is packaged in smaller granules
and iodine stains it a red colour. In brown seaweed (Phaeophyta),
in particular kelp species classified as Laminarans, have a
glucan that is the least similar to land plant starches. To
see the reactions of these algal species to iodine it is very
important to know the species of seaweed you are testing and
whether it is a brown, green or red seaweed. You will probably
want to do your iodine tests on fresh seaweed and looking at
how the iodine stains the cells, by looking at them through
a microscope.
Good luck on your project,
it sounds great!
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Green
Sand - received
from D. Besack in PA.
Q: While in N.Carolina in
the beginning of August we were on the beach at night and when
we walked the sand started to glow green where the pressure
from our feet where ever we stepped-also when we splashed in
the water the same thing happened. Could you please figure
this out? We thought it was so neat!! Thanks for all your help.
A: What you saw in the wet
sand and in the water is called bioluminescence.
Bioluminescence is the phenomenon of organisms producing light with an energy-releasing
chemical reaction.
 There
are millions of microscopic algae in the surface waters
of the ocean. Some of these algae (mostly one group called
the Dinoflagellates) have the ability to emit light for
a very brief amount of time (0.1 to 0.5 seconds). They
emit light when agitated, which is why you saw them where
you stepped and where you splashed around. This is a mechanism
that helps protect them from predators - because it reveals
the predator to its predator.
There are many organisms that bioluminesce for different reasons, including
deep sea fish, jellyfish, and fireflies.
Check out this site for more info about bioluminescence, dinoflagellates,
and other bioluminescing organisms:
Monterey Bay Aquarium Bioluminescence research page
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Ocean
Plants - received
from Stephanie in Texas
Q: What
kinds of plants are in the oceans? Like what are the plants
names?
A: There many different kinds of plants in the ocean. Most of them
are seaweeds (marine algae). There are 3 majoy types of seaweeds:
The reds: Rhodophyta (e.g. Chondrocanthus [Turkish Towel] and Porphyra [Nori])
The browns: Phaeophyta (e.g. Macrocystis [Giant kelp] and Nereocystis [Bull Kelp])
The greens: Chlorophyta (e.g. Ulva [sea lettuce])
But, seaweeds aren't the only types of plants in the ocean. There are some vascular
plants as well. (Seaweeds do not have a vascular system ("sap") the
way land plants do). Intertidal plants like surfgrass (Phyllospadix) and eelgrass
(Zostera) are also important ocean plants.
Plants in the ocean are not just the primary producers that are the foundation
of the food chain but they also build important habitat for invertebrates and
juvenile fish.
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Red
Algae - received
from Lucie in Vancouver.
Q: What are the predators/prey of red
algae?
A: Red algae
is autotrophic, which means that it turns inorganic nutrients into organic
nutrients through
the process of photosynthesis. For this reason, i wouldn't really consider
red algae to be a predator of anything, and therefore doesn't have "prey".
There are however, a number of organisms that prey on red aglae. Some of
these include fish, abalone, gumboot chitons, and decorator crabs.
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Sea
Sacks
Q: What is a sea sack?
A: A sea sack is a type of red algae (Phylum
Rhodophyta) called Halosaccion glandiforme. It also goes by the other common
names of Dead man's fingers, sea sacs, and salt sacs. They are found from
the Aleutian Islands, Alaska to Point Conception, Calfornia. Sea sacs prefer
exposed, rocky habitats, in the mid intertidal zone. They are yellowish in
colour, and filled with water. You can probably find a picture in any intertidal
field guide (can be purchased at a local bookstore). You can find a pictures
of sea sacks by "Google-ing" images of 'sea stacks'.
Find out how sea stacks are formed at this site!
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Algae
structure - received on from Kevin in New York
Q: How does a stipe, blade, and pneumatocyst
pertain to marine algae?
A: To make an analogy to land plants:
a stipe is like a stem, and a blade is like a leaf. The blade of the algae
will be responsible for photosynthetic process, and the stipe provides support
and height, in order for the algae to reach near the lighter areas of surface
water. For a diagram of the position of the stipe and blade on a common west
coast kelp go to our seaweed page. A
pneumatocyst (or bulb) refers to a float used to keep the blades of the algae
near the surface.
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Anti-sinking
methods - received on from Kelly in Bristol
Q: Could you tell me some methods that
zooplankton use to stop themselves from sinking?
A: For many phytoplankton and zooplankton,
it is vital to remain at the surface in order to survive. Phytoplankton need
to stay in the photic zone in order to photosynthesize, and the zooplankton
need to stay near the phytoplankton in order to feed!
Four mechanisms enable plankton to float:
1. they are less dense than seawater
2. their shape increases drag, thus reducing settling velocity
3. they have some control over vertical distribution using their own locomotion
4. water turbulence to stay suspended
Most plankton are more dense than seawater, but flotation structures, such
as long, elaborate spines to increase surface area, and gas-filled sacs. Some
plankton can even collect low density ions and expel high density ions. Some
zooplankton also have some control over their own locomotion such as jelly
bell-pulses and crustacean swimming appendages.
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see also: OceanLink's Seaweeds pages
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