118
been detected. It is known for causing fi sh and seabird death when its
abundance is high and for having a potential toxicity on human consumed
shellfi sh. On October 6, nutrient concentration combined with a weak
hydrodynamic state triggered a large development of this species.
Concentration reached up to 450 cells/cm
3 , leading to a fast increase in
chlorophyll concentration (>20 µg Chl a /dm
3
). However, these dinofl agellates
were quickly affected after a sudden wind (mistral, 330°–360°) event
with mean speed exceeding 20 m/s: on October 7, 2011, A. sanguinea
abundance dropped down below 20 cells/cm
3 .
These results, out of reach of more conventional methods with manual
sampling, underline the power of in situ automated monitoring to follow
in near real time the dynamics of phytoplankton in general and also to
target some particular species of interest such as harmful algae.
1
Introduction
Phytoplanktonic species play a key role for
marine productivity. These primary producers
fuel the entire trophic network and modulate
biogeochemical cycles (N, C, P, Si, S, Fe). When
environmental conditions favor their bloom,
some species can be responsible for massive
death of organisms, commercial species
(Smayda 1997 ). These events, known as harmful
algal blooms (HABs), represent a major risk for
the marine fauna, from fi lter feeders to fi shes, but
also marine mammals and seabirds, as they can
be subject to toxic or nontoxic (anoxia, gill clogging, physiological changes) effects leading to
their death (Zigone and Enevoldsen 2000 ). HABs
are caused by numerous species of dinofl agellates, cyanobacteria, diatoms, prymnesiophytes,
and raphidophytes which are harmful in many
ways. Thus, they require an accurate monitoring
to detect them as early as possible.
Phytoplankton analyses are based on their
optical properties via microscopy or fl uorimetry,
both considered as traditional methods used to
detect algal proliferations (Anderson et al.
2001 ). In France, the national program REPHY
(REseau de surveillance du PHYtoplancton et
des PHY-cotoxines) conducted by IFREMER
(Institut
Français
de
Recherche
pour
l’Exploitation de la MER) is in charge of phytoplankton surveys along the French shore. It aims
at enhancing our understanding about factors
controlling phytoplanktonic blooms. By means
of early warnings, this network also intends for
preventing poisoned shellfi sh consumption by
triggering some particular toxic species.
Observations are based on microscopic counts
which are time consuming and require expertise.
The sampling frequency is, typically, from one
per month to up to one per week during risky
periods (in May/June for most of the sites).
Located in the south of France, the Berre
lagoon is one of the largest marine lagoons in
Europe and around the Mediterranean Sea. Because
it has received a large amount of nutrients over
the years, the lagoon used to regularly host
algal blooms characterized by the dominance of
few species, with extreme biomass (Malkassian
2012 ). Since 1995, this site benefi ts from a
special attention relying on European (Directive
Cadre sur l’Eau (DCE)), regional (Réseau de
Suivi Lagunaire (RSL)), and local (Groupement
d’Interêt Public pour la Réhabilitation de l’Etang
de Berre (GIPREB)) frameworks. In general,
lagoons are both highly dynamic and sensitive to
human activities because of their intermediate
state between land and sea. Besides a long-term
monthly monitoring of phytoplankton in the
Berre lagoon, it appears that the establishment
of the annual budget of primary production is
still incomplete. This is likely due to important
seasonal changes (with, for instance, sporadic
M. Dugenne et al.
been detected. It is known for causing fi sh and seabird death when its
abundance is high and for having a potential toxicity on human consumed
shellfi sh. On October 6, nutrient concentration combined with a weak
hydrodynamic state triggered a large development of this species.
Concentration reached up to 450 cells/cm
3 , leading to a fast increase in
chlorophyll concentration (>20 µg Chl a /dm
3
). However, these dinofl agellates
were quickly affected after a sudden wind (mistral, 330°–360°) event
with mean speed exceeding 20 m/s: on October 7, 2011, A. sanguinea
abundance dropped down below 20 cells/cm
3 .
These results, out of reach of more conventional methods with manual
sampling, underline the power of in situ automated monitoring to follow
in near real time the dynamics of phytoplankton in general and also to
target some particular species of interest such as harmful algae.
1
Introduction
Phytoplanktonic species play a key role for
marine productivity. These primary producers
fuel the entire trophic network and modulate
biogeochemical cycles (N, C, P, Si, S, Fe). When
environmental conditions favor their bloom,
some species can be responsible for massive
death of organisms, commercial species
(Smayda 1997 ). These events, known as harmful
algal blooms (HABs), represent a major risk for
the marine fauna, from fi lter feeders to fi shes, but
also marine mammals and seabirds, as they can
be subject to toxic or nontoxic (anoxia, gill clogging, physiological changes) effects leading to
their death (Zigone and Enevoldsen 2000 ). HABs
are caused by numerous species of dinofl agellates, cyanobacteria, diatoms, prymnesiophytes,
and raphidophytes which are harmful in many
ways. Thus, they require an accurate monitoring
to detect them as early as possible.
Phytoplankton analyses are based on their
optical properties via microscopy or fl uorimetry,
both considered as traditional methods used to
detect algal proliferations (Anderson et al.
2001 ). In France, the national program REPHY
(REseau de surveillance du PHYtoplancton et
des PHY-cotoxines) conducted by IFREMER
(Institut
Français
de
Recherche
pour
l’Exploitation de la MER) is in charge of phytoplankton surveys along the French shore. It aims
at enhancing our understanding about factors
controlling phytoplanktonic blooms. By means
of early warnings, this network also intends for
preventing poisoned shellfi sh consumption by
triggering some particular toxic species.
Observations are based on microscopic counts
which are time consuming and require expertise.
The sampling frequency is, typically, from one
per month to up to one per week during risky
periods (in May/June for most of the sites).
Located in the south of France, the Berre
lagoon is one of the largest marine lagoons in
Europe and around the Mediterranean Sea. Because
it has received a large amount of nutrients over
the years, the lagoon used to regularly host
algal blooms characterized by the dominance of
few species, with extreme biomass (Malkassian
2012 ). Since 1995, this site benefi ts from a
special attention relying on European (Directive
Cadre sur l’Eau (DCE)), regional (Réseau de
Suivi Lagunaire (RSL)), and local (Groupement
d’Interêt Public pour la Réhabilitation de l’Etang
de Berre (GIPREB)) frameworks. In general,
lagoons are both highly dynamic and sensitive to
human activities because of their intermediate
state between land and sea. Besides a long-term
monthly monitoring of phytoplankton in the
Berre lagoon, it appears that the establishment
of the annual budget of primary production is
still incomplete. This is likely due to important
seasonal changes (with, for instance, sporadic
M. Dugenne et al.