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The bio-concentration is the direct in crease in concentration of a pollutant when it passes from water in a watery organization. The has bio-accumulation is the sum of absorptions of a
pollutant per direct and food way by watery species. This phenomen on of bio-accumulation
is well-known thanks to certain species able to accumulate amounts of natural substances
several thousands of times beyond the concentration which one meets in the ground. Thus,
the algae of the wrack types or Laminaria are able to accumulate bromine and iodine
present in the water of the seas what is made profitable in the industrial extraction of
these products Plutor ejected by the man in the oceans coming from the treat ment plants
of the radioactive waste can be concentrated up to 3000 times by the phytoplankton and
1200 times by the benthic algae. This phenomen on has as a consequence a transfer and a
biological increase in pollution inside the contaminated biocénoses. Each trophic chain
will be the site of a process of increase in concentration in the persistent pollutants in
the biomass as one goes up in the various levels of the ecological pyramid.
In the natural middle, one can consider,
except extreme cases, that the organizations are in the presence of concentration of
insufficient pollutant to kill them. But even if short-term effects are thus not always
visible in the long run, on the other hand, one ends up feeling effects on the respiratory
and nutritional behaviors.
The presence of phosphate, of nitrogen
ammoniacal and organic and of nitrate, support the nutrition of the algae. According to
the concentration of these various products, it may be that the diversity and the
productivity of the algae are affected. Thus
the knowledge of the rate of absorption of organic nitrogen by algae of mediums polluted
such as Anteromorpha and Ulva, can give a base of explanation of the pullulation of
species to depend on others. Indeed, these algae showed a great facility of assimilation
of amino acids present in waste water and rich in organic matter. On the contrary, the
soft red algas and the brown algas have a weak capacity of accumulation of these amino
acids. What could explain, partly, disappearance in the polluted zones of the
Mediterranean of the brown algas of the kind will cystoseira, replaced either by the
calcified red alga Corollina,or by of Protofloridées, or by of Ulva or Entéromorpha.
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