Affiliation(s)
1. Laboratory of Phytoplankton and Primary Production, Instituto del Mar del Peru, Chucuito, Callao 07001, Peru
2. Functional Area of Research in Physical Oceanography, Instituto del Mar del Peru, Chucuito, Callao 07001, Peru
3. Functional Area of Research in Chemical Oceanography, Instituto del Mar del Peru, Chucuito, Callao 07001, Peru
ABSTRACT
During 2013-2015, a series of
bio-oceanographic surveys was carried out in Paracas bay (13°50′ S). This coastal
habitat represents a transition between open ocean and continent. Changes in
distribution and structure of phytoplankton community and presence of noxious
algal blooms were evaluated. The vertical stability of water column was analyzed
on transects of temperature, salinity and potential density. Stratification of
the water column as well as other variables presented a seasonal behavior. The
maximum values were recorded in summer and were directly related to the
seasonal heat flux in surface layers of the bay, while in winter this
stratification index was minimum. N/P ratios showed a seasonal variation with
highest values in winter and lowest ones in summer. Silicate concentrations
were minimum mainly during in spring due to high biological fixation. The
dominance of diatoms was evident in winter and spring, with maximum abundances
of r strategists. The diversity and
equitability indexes were low (< 3 bitscel-1 and 0.31, respectively). During
summer, there was a greater
contribution of oceanic species, with high concentrations of the dinoflagellate Prorocentrum cordatum; and a higher frequency of algal blooms (Akashiwo sanguinea, Heterosigma akashiwo, Eutreptiella
gymnastica and Gonyaulax polygramma)
in the coastal zone. Silicates and pH presented a significant correlation with
diatom abundances in spring, whilst dinoflagellates were associated to warm and
salinity conditions in summer. Weak correlations were found for potentially
toxic dinoflagellates with temperature and for Pseudo-nitzschia group with silicates and phosphates.
KEYWORDS
HAB, transition zones, inshore ecosystem, Paracas bay-Peru,
phytoplankton.
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