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A B
C D E
F G H
I
J K L M
N O P Q
R S T
U V W X Y
Z
A
Where
oxygen is present.
Metabolism
characterised by the consumption of oxygen.
Type
of interaction between species where the development of one
species is inhibited without the other being affected;
see table
Process
involving the use of an inorganic oxide compound other than
oxygen (sulphates, nitrate, nitrite and carbonates, for example)
as a final electron acceptor.
Degree
of hydrodynamic communication between a lagoon and the surrounding ocean. Can
be calculated using the following linear quotient: (passes + hoas + immersed crown) / the perimeter of the atoll.
Zone
where there is no light, and where no photosynthesis
can therefore occur.
Asexual
reproduction does not require gametes and zygotes (as in the
budding, for example).
It
is a fast process which results in large numbers of
offspring. It is the sole mode of reproduction used by
procaryotes (organisms with no nucleus).
A
coral reef complex with no volcanic outcrops, which emerges
from the high seas even at high tide. Atolls are often
ring-shaped and have a central lagoon.
For
further information: see diagram of a typical Tuamotu atoll
A
living organism capable of synthesising organic compounds
using mineral elements collected in the environment and an
external source of energy.
This
energy can be of the following kinds:
-
solar energy (in the case of green photosynthesising plants)
-
the energy resulting from exothermic chemical reactions (in
processes involving chemio-synthesising bacteria)
-
the energy resulting from both processes combined (in
processes involving chemio-photosynthesising bacteria).
Phytoplanktonic
organisms are the main primary producers in marine
environments, where they constitute the basis of the food
chain.
For
further information, see:
"Photosynthesis".
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B
A
group of aquatic organisms living either at the surface of the
sedimentary layer or within this layer.
The
benthic macrofauna (those larger than 1 mm) inhabiting marine
sediments (such as the polychetic annelids) can serve as
" biological indicators", since they reflect any
disturbances in the marine ecosystem.
Accumulation
with time of a substance which cannot be excreted (such as a
metal or chlorinated hydrocarbons) in the tissues of an organism.
A balanced group of
animals and plants stably (either permanently or cyclically)
occupying a given biotope.
Degradation
of substrates such as the calcium carbonate forming coral
reefs by various living organisms ( such as micro- and macro-
drillers and grazers); see figure
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INTRA-SPECIES
relations
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Individual 1
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Individual 2
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Competition
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+
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-
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Co-operation
A
beneficial
but non- indispensable association between two
individuals
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+
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+
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INTER-SPECIES
relations
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Species 1
|
Species 2
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Neutralism
Neither of the two species is affected by its association with the other
species
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0
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0
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Competition
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+
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-
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Co-operation
A
beneficial
but non- indispensable association between two species
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+
|
+
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Predation
Species 1 =
the predator ; Species
= 2 the prey
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+
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-
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Mutualism
Species 1 =
the symbiont ; Species = 2
the host
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+
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+
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Commensalism
Species 1 =
the symbiont
; Species = 2
the host
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+
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0
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Parasitism
Species 1 =
the symbiont
; Species = 2
the host
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+
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-
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An
increase occurring at each stage in a trophic chain in the
concentration of a polluting substance (such as the toxin from
a dinoflagellate organism, mercury, etc.) bio-accumulated
in the tissues of the host organism.
As
the result of this process, the predators at the end of the
food web harbour the highest
concentrations (and contract diseases such as Ciguatera,
Minamata's disease, etc.)
Sedimentary
changes caused by the movements and modes of feeding used by the
fauna inhabiting these sediments.
The
sudden occurrence of high concentrations of phytoplankton which
have been intensively produced due to the occurrence of
particularly favourable feeding conditions (as the result of
upwelling: the rise of deep oceanic waters carrying abundant
nutrients).
A
photosyntetic organism
belonging to the category of cyanobacteria.
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C
A
process whereby calcium ions and carbonates combine to form
chalky skeleton-like materials (click
here for the explanation of the chemical reaction).
A
pigment found in green plants which is responsible for the capture of the
photons used in the process of photosynthesis.
A
class of fish consisting of 2 higher orders : Squalomorphs (sharks)
and Batoids (sting-ray).
Ciguatera
is a tropical ecotoxicological phenomenon affecting coral
ecosystems. It is caused by a benthic micro-organism, the
dinoflagellate Gambierdiscus toxicus, and results in natural
substances which are toxic to humans being accumulated in the
muscles and viscera of herbivorous fish and their predators (biomagnification).
See
" For further information, click on "ciguatera"
A
state particular to animals living with other organisms and sharing their
food but not feeding on their organic matter.
Communities
are groups of populations which have been found in ecological studies to
interact with each other.
A
situation where two or more organisms vie for the same
source of food when there is a shortage of supplies in
comparison with the demands.
Competition
can occur within a species, as well as between individuals
of the same species, or between species, between individuals
belonging to different species and possibly different genera.
A
carnivorous animal which feeds mainly on coral.
The emergent land forming
the periphery of an atoll.
A
class of organisms capable of performing photosynthesis,
which emerged 3.5 billion years ago; some of these organisms
are capable of fixing molecular
nitrogen (N2).
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D
Suspended
debris of organic or mineral origin.
Unicellular algae
characterised by a siliceous external skeleton.
Dinoflagellate algae are
unicellular algae which are characterised by a wide range of
forms (the largest of which, Noctiluca, can measure up to 2 mm
in diameter).
Most of these algae carry
out photosynthesis, process their nutrients using light energy
(see Photosynthesis) and constitute
a source of food for other organisms.
The coastal
dinoflagellate species are the most harmful to humans,
especially during the warmest months of the year, when efflorescences
("red tides") tend to occur. These occurrences
damage the marine ecosystem because of the neurotoxin produced
by dinoflagellate algae, which propagates via biomagnification
process along the trophic chain in increasing proportions
until being ingested by humans.
Some dinoflagellate algae
are involved in other eco-toxicological processes such as
ciguatera (See "For further
information, click on ciguatera" ).
Dissolved
molecules resulting either from the degradation of dead
organisms or from molecular excretions (the matter exudated
by phytoplankton, for example).
Diversity refers to the
number of species living in a specific type of habitat in a
given region.
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E
-
ECOSYSTEM
A
community consisting of plants, animals and other organisms
which have energy fluxes and nutrients in common and
interact with each other and with the physical environment. This
association is characterised by biocenosis
and by a specific biotope.
The
Amazonian forests, the deserts and the coral reefs are all
well-known examples of ecosystems.
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ENDOSYMBIOSIS
A
particular type of symbiosis where
one of the partners involved (zooxanthellae, for example)
inhabits the cells of the other (in this case, polyps).
-
EPIPSAMMIC
(species)
A
species inhabiting sandy environments
A
pluricellular organism (algae, animals) with a clearly separated nucleus
surrounded by a nuclear envelope.
Refers to zones
containing high concentrations of nutrients,
which gives rise to a high level of biological productivity.
Enrichment
of waters with nutrient substances (such as nitrogen and
phosphorus), which usually leads to environmental changes
such as an increase in the production of algae, sometimes of
a toxic kind, and other aquatic plants; the outcome is
usually that the habits of all the users of this particular
environment are disturbed.
This
additional nutrient input can have the following results:
-
low
dissolved oxygen concentrations
(Hypoxia)
-
the
absence of dissolved oxygen (Anoxia)
-
reducing
conditions with high hydrogen sulphide (H2S)
levels in the deep waters and sediments
- changes
in the biodiversity of the ecosystem
The vertical ocean zone
into which sufficient sunlight penetrates for photosynthesis
to be possible.
The euphotic zone
is generally taken to be the zone (maximum depths: 150 m)
where the light amounts to at least 1% of the surface light
and plants are therefore able to grow, as opposed to the disphotic
zone, where there is little if any plant growth and the aphotic
zone, where no plant life is possible at all.
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F
G
An
electronic device which uses satellite positioning signals to exactly
determine the longitude and the latitude.
It
is used to locat offshore and high sea sampling stations. Since the year
2000, the G.P.S has been accurate to within a few meters.
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H
Halophile
plants are species which are living on salted grounds.
An animal producing both
male and female gametes.
An organism deriving
energy from organic matter produced by other organisms.
A
gap in the inner reef flat parts of the coral rings and the
barrier reefs covered with "motus"(see this term),
which often makes it possible for the ocean waters to reach
the lagoon. There exist, however, some "hoas" where
this is not the case.
The
"hoas" alternate with "motus".
A way
of seed and spore transport by the sea (marine currents for
example).
A decrease in the oxygen
input or in its use by the tissues.
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I
The
amount of radiant energy emitted per second on all wavelengths by the Sun and
reaching a surface with an area of one square meter outside the Earth's
atmosphere.
Top
L
A
depression of variable size, located either behind a barrier
reef or surrounded on all sides by a coral ring.
Example:
the Tikehau
lagoon in French Polynesia.
The stage of development
between the formation of an egg and metamorphosis.
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M
Benthic
animals measuring more than one millimeter
Pluricellular
algae. Benthic macroalgae is the term used to describe the
multicellular organisms associated with
sediments.
A
mass of water is a fairly large quantity of oceanic water extending both
horizontally and vertically, with a specific density
Animals measuring between
0.1 mm and 1.0 mm living in sediments.
A
nutrient regeneration cycle whereby nutrients are reincorporated into the
trophic chain. This process is controlled by bacteria and protozoans.
Benthic animals less than
0.1millimeter in size; most of them are protozoa.
Unicellular algae (such
as pennate diatom species) and cyanobacteria
associated with both loose and hard substrates.
Interactions which are
mutually beneficial to both species involved.
A small, separate islet
of variable size formed by detritus, possibly including blocks
of stone, located above
the coral reef of an atoll or the barrier reef of a high
island. Most motus form strings of islets separated by hoas
("Eléments de terminologie récifale Indopacifique",
published by Téthys - vol.7 no. 1, 1975).
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N
One
of the three main ecological groups in the classification of marine organisms.
The other two are benthos
and plankton.
Nekton
consist of pelagic organisms such as fish, some crustaceans, cephalopods and
marine mammals which are able to swim against the currents.
Depth
at which the nitrate concentration starts to increase sharply.
Dissolved
molecular nitrogen (N2
gas) is fixed by cyanobacteria
using the enzyme nitrogenase (the gene coding for
nitrogenase is the Nif gene). After being fixed by these
organisms, nitrogen is used to synthesise protein.
The
whole set of organic and inorganic compounds and ions (such as the nitrous and
phosphoric compounds, for example) which provide the primary producers (phytoplankton)
with their main source of food.
Alternation
between the day and night.
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O
Refers
to regions where nutrients are in short supply, which
results in a low level of biological productivity.
Class
of vertebrates mainly containing the super-order of Teleostei.
A
term describing animals which lay eggs that hatch only after a
period of embryonic development occurring outside the female
genital organs.
It
is used in opposition with viviparous, which refers to animals
where the females give birth to juveniles or to fully formed larvae.
Either there are no eggs, or the eggs are kept inside the
female genital organs until they hatch.
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P
Ensemble des particules
organiques, mortes ou vivantes, en suspension dans les eaux.
Large gap in a barrier
reef or coral ring which is wide and deep enough for
navigation to be possible. The lagoon waters transit mainly
via these passes.
Refers to the ocean water
column and the organisms inhabiting it.
The
pH can be used to assess the "dissolved carbonic acid versus
carbonate" balance in a mass of water. This balance depends on both
physical and biological factors. The carbonic gas produced in situ by
the respiratory systems of marine organisms and by the process of
remineralisation of dead organic matter will tend, for instance, to decrease
the pH of the water; whereas unproductive waters containing little plankton
and organic matter will have high pH levels.
Inhibition of
photosynthesis resulting from very high light intensities.
The
respiration of some plants, which is activated by light.
Biochemical
process occurring in the chloroplast of plants: this process
enables plants to use
carbon dioxide, water and light energy to produce energy-rich
organic compounds. See: "For
further information, click on Photosynthesis".
Microscopic
planktonic algae and cyanobacteria (diatoms, dinoflagellates, etc.)
Set
of organisms carried back and forth by water. They drift quite
passively in moving water masses, apart from some vertical
migration (which matches the nycthemeral rhythm).
The
concepts of autotrophy and heterotrophy
serve to distinguish between phytoplankton (plant
plankton) and zooplankton (animal plankton).
Holoplankton
are organisms which spend their whole lifetime among the
plankton.
Meroplankton
are benthic organisms in the larval phase which spend the
beginning of their lives among the plankton.
There
exist various size classes of plankton: picoplankton (<2 or
3 µm in size), nanoplankton (3 to 35 µm), microplankton (35
to 200 µm), mesoplankton (200 to 1000 µm) and macroplankton
(>1000 µm).
Predation leads to the
development of one living species at the expense of another. Parasitism is an
obligatory form of predation; see
Table
The amount of organic
matter synthesised by plants from inorganic substances; it is
expressed in terms of weight per unit volume or area per unit
time.
Unicellular
organisms (bacteria, cyanobacteria) with no distinct nucleus.
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R
The
residence time characterises the exchanges occurring between
the lagoon and ocean waters, taking the capacity of the lagoon
into account. The residence time can be calculated in several
ways. One method consists of calculating the ratio between
the capacity of the lagoon and the volume of the net
annual exchanges occurring at the surface. This requires
having a sufficiently large number of measurements of the
waters exchanged via the passes connecting the lagoons to the
open sea.
A
metabolic process occurring in all organisms in which
organic substances are decomposed and converted into energy;
unlike photosynthesis, it results in the production of
carbon dioxide.
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S
The
Secchi disc provides a simple means of measuring the
transparency of water.
It
is usually 30cm in diameter and painted white.
The
disc is immersed in the water until it is no longer visible,
and the depth at which it has disappeared from sight is
recorded. This method was developed by A. Secchi in 1866.
Long-term
physical association between two living organisms (such as
polyps and zooxanthellae - See "Click
here for further information").
This
association can be either mutually beneficial or result from
parasitism. (v. endosymbiosis).
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T
Fish
with a bony skeleton
Depth
at which the largest change in the temperature occurs.
Position
occupied by an organism in the food chain: primary
producers (phytoplankton, higher plants, etc.), primary
consumers (herbivora such as zooplankton), secondary consumers (carnivora,
etc.
The
weight of all the particulate matter present per unit volume of water.
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U
The
rise of deep water rich in nutrients
towards the surface of the sea.
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X
Xerophile
plants are species which are well adapted to the dryness.
Z
Presence
of one or more species within characteristic, easily
recognisable regions defined by a given range of depths (in
the water column) or heights (a tidal range).
Benthic
animals
way
of seed and spore transport by animals
Animal
Plankton
Group
of dinoflagellates forming an endosymbiotic
association with polyps: corals are said to be hermatypic,
for example; but when there are no zooxanthelles, corals are
said to be ahermatypic.
See
- "For further information,
click on Zooxanthellae."
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