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Publication
Phyto- and zooplankton dynamics in two ICOLLs from Southern Portugal
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Advisor(s)
Abstract(s)
Foz do Almargem and Salgados are two small, intermittently closed and open lakes and
lagoons (ICOLLs) located in the Portuguese southern coast, both remaining isolated from
the sea throughout great part of the year. Based on environmental and biotic parameters,
the first lagoon was classified as mesotrophic, with a greater marine influence, while the
second one was classified as hypereutrophic. The plankton relations and seasonal variation
were examined in both lagoons aiming at understanding the biological patterns here
present and relating them with the environmental conditions, as well as inferring possible
top-down or bottom-up control in the communities, determining also in which alternative
trophic state they are: a clean-water lagoon, with submerged macrophyte vegetation; or a
turbid-water lagoon, with only phytoplankton as primary producer.
The plankton community greatly differs in the two lagoons. Salgados lagoon presented
extremely high concentrations of phytoplankton, which form blooms throughout the year,
mostly composed by potential harmful organisms. This lagoon also had very high densities
of zooplankton. Phytoplankton and zooplankton density were always lower in Foz do
Almargem. Rotifera, Ostracoda and Cladocera dominated the Zooplankton community in
Salgados. In Foz do Almargem, Rotifera also dominates, together with other groups, such as
annelids, crustaceans and mollusks larvae, which denotes a stronger marine influence. In
both lagoons, organisms with body size inferior to 100 mm mainly composed the
zooplankton. In Salgados lagoon, excess nutrient load induced a high density of
phytoplankton, which is utilized by a high density of zooplankton, following a bottom-up
control model. The lagoon clearly showed a permanent turbid-water alternative state due
to excess nutrients. On Foz do Almargem, the frequent openings of the inlet throughout the
wet season caused strong physical disturbance, which prevented the development of a
stable planktonic community.
Description
Keywords
Intermittently closed and open lakes and lagoons (ICOLLs) Bottom-up and top-down control Ecosystem alternative states Turbid-water vs. clear-water state ICOLLs management Lake Predation
Citation
Publisher
Elsevier