The Maracaibo System, Venezuela
53
strate changes as a result of natural turbulence and continuous dredging
operations. The subtidal benthic community of Tablazo Bay extends into
the lake, though Mytella disappears and densities of polychaetes are much
lower.
3.3.2 Plankton Communities
Similar to the distribution of benthic species, the composition of the
phytoplankton community in the Maracaibo System, with 125 species of
diatoms (Hustedt 1956), clearly follows a salinity gradient. Phytoplankton
in the southern part of the gulf is composed of dinoflagellates (i.e., Noctiluca scintillans, Porocentrum micans) and 19 diatoms, such as Chaetoceros afinis, C. decipiens, C. seriacanthus, Rhizosolenia calcar-avis, R.
imbricata, and R. robusta. About 50 diatom species (i.e., Sceletonema costatum, Chaetoceros subtilis) and cyanobacteria (Anabaena spiroides,
Microcystis aeruginosa) are found in the strait. The dinoflagellates Ceratium furca, C. massiliense, C. tripos, and Gymnodinium simplex have been
recorded in Tablazo Bay where Chlorophyta (i.e., Scenedesmus quadricauda, S. dimorphus, Ankistrodermus falcatus) are poorly represented. The
distribution of the dinoflagellates Ceratium Jus us, C. tripos, and Dinophysis
caudata extends from the bay into the southernmost part of the lake.
Twelve species of diatoms and the green algae Ankistrodermus falcatus are
only found in the lower Limon River. The phytoplankton community in the
lake is represented by abundant (>500 cells ml- 1 ) Chlorophyta ( Chodatella
longispina, Stichococcocus bacillaris, Ankistrodemus gracilis, Selenastrum
gracile, Scenedemus quadricauda, S. dimorphus, Tetraedron caudatum,
Pediastrum tetras, Agmenellum quadriduplicatum), cyanobacteria (Anacystis cyanea, Oscillatoria submembranacea, Spirulina sub salsa, Anabaena
spiro ides), and about 37 diatoms (i.e., Chaetoceros similoides, Melosira
ambigua, Plagiogramma tenuissimum, Nitzchia palea; Battelle 1974).
The zooplankton in the Gulf of Venezuela is typically composed of neritic
species (i.e., Lucifer faxoni, Centropages furcatus, Acartia lilljeborgi, and
stomatopod larvae) and, together with pelagic elements (i.e., the pteropod
Cresseis acicula, the tunicate Salpa democratica, and siphonophores), zooplankton biomass may reach 40 mg m- 3 • Tablazo Bay acts as an interface
between euhaline species of the gulf and oligohaline species of the lake.
The polihaline waters at the mouths of the bay constitute the distributional
limit for several neritic species as well as for meroplanktonic species of the
bay. The abundance of allochthonous plankters, like Sagitta hispida, S. enflata, Bowmaniella brasiliensis, Aegathoa linguifrons, Acetes americanus,
Lucifer faxoni, Cresseis acicula, larvae of Penaeus, carideans, brachyurans,
53
strate changes as a result of natural turbulence and continuous dredging
operations. The subtidal benthic community of Tablazo Bay extends into
the lake, though Mytella disappears and densities of polychaetes are much
lower.
3.3.2 Plankton Communities
Similar to the distribution of benthic species, the composition of the
phytoplankton community in the Maracaibo System, with 125 species of
diatoms (Hustedt 1956), clearly follows a salinity gradient. Phytoplankton
in the southern part of the gulf is composed of dinoflagellates (i.e., Noctiluca scintillans, Porocentrum micans) and 19 diatoms, such as Chaetoceros afinis, C. decipiens, C. seriacanthus, Rhizosolenia calcar-avis, R.
imbricata, and R. robusta. About 50 diatom species (i.e., Sceletonema costatum, Chaetoceros subtilis) and cyanobacteria (Anabaena spiroides,
Microcystis aeruginosa) are found in the strait. The dinoflagellates Ceratium furca, C. massiliense, C. tripos, and Gymnodinium simplex have been
recorded in Tablazo Bay where Chlorophyta (i.e., Scenedesmus quadricauda, S. dimorphus, Ankistrodermus falcatus) are poorly represented. The
distribution of the dinoflagellates Ceratium Jus us, C. tripos, and Dinophysis
caudata extends from the bay into the southernmost part of the lake.
Twelve species of diatoms and the green algae Ankistrodermus falcatus are
only found in the lower Limon River. The phytoplankton community in the
lake is represented by abundant (>500 cells ml- 1 ) Chlorophyta ( Chodatella
longispina, Stichococcocus bacillaris, Ankistrodemus gracilis, Selenastrum
gracile, Scenedemus quadricauda, S. dimorphus, Tetraedron caudatum,
Pediastrum tetras, Agmenellum quadriduplicatum), cyanobacteria (Anacystis cyanea, Oscillatoria submembranacea, Spirulina sub salsa, Anabaena
spiro ides), and about 37 diatoms (i.e., Chaetoceros similoides, Melosira
ambigua, Plagiogramma tenuissimum, Nitzchia palea; Battelle 1974).
The zooplankton in the Gulf of Venezuela is typically composed of neritic
species (i.e., Lucifer faxoni, Centropages furcatus, Acartia lilljeborgi, and
stomatopod larvae) and, together with pelagic elements (i.e., the pteropod
Cresseis acicula, the tunicate Salpa democratica, and siphonophores), zooplankton biomass may reach 40 mg m- 3 • Tablazo Bay acts as an interface
between euhaline species of the gulf and oligohaline species of the lake.
The polihaline waters at the mouths of the bay constitute the distributional
limit for several neritic species as well as for meroplanktonic species of the
bay. The abundance of allochthonous plankters, like Sagitta hispida, S. enflata, Bowmaniella brasiliensis, Aegathoa linguifrons, Acetes americanus,
Lucifer faxoni, Cresseis acicula, larvae of Penaeus, carideans, brachyurans,