Micro and mesozooplankton composition during winter in Ushuaia and Golondrina Bays (Beagle Channel, Argentina)

Abstract

The current paper analyses the micro and mesozooplankton in Ushuaia and Golondrina Bays, the first research on these plankton fractions of these areas in wintertime (August 2004). The number of microzooplankton and mesozooplankton taxa was higher in Ushuaia Bay than in Golondrina Bay. Aloricate ciliates predominated over tintinnids in microzooplankton and holoplankton over meroplankton in mesozooplankton in both bays. Ctenocalanus citer, Drepanopus forcipatus and Clausocalanus brevipes presented the highest frequency of occurrence. Among the meroplankton, Halicarcinus planatus and Munida gregaria were the most frequent decapod larvae in both bays. The distribution of the different sampling station groups of microzooplankton and mesozooplankton as determined by cluster analysis suggests the influence of natural conditions in each bay and anthropogenic environmental differences between the two bays. RESUMOEste trabalho analisa o micro e o mesozooplâncton das Baías Ushuaia e Golondrina, constituindo a primeira pesquisa realizada nessas áreas sobre estas frações do plâncton no inverno (agosto 2004). O número dos taxa do microzooplâncton e do mesozooplâncton foi mais elevado na Baía Ushuaia do que na Baía Golondrina. Os ciliados aloricados foram dominantes sobre os tintinídeos, enquanto que no mesozooplâncton o holoplâncton foi dominante nas duas baías. Ctenocalamus citer, Drepanopus forcipatus e Clausocalamus brevipes foram as espécies mais freqüentes. No meroplâncton, Halicarnus planatus e Munida gregaria foram as larvas de decápodes mais freqüentes em ambos os locais. Os diferentes grupos de estações formados em função do microzooplâncton e do mesozooplânkton, e detectados na análise de agrupamento, sugerem a influência de condições naturais em cada baía e de diferenças ambientais antropogénicas entre as duas baías.Descriptors: Microzooplankton,

Monstrilloida (Crustacea: Copepoda) from the Beagle Channel, South America

“…The genital double somite is relatively longer in the Argentinian specimens, 1.75 times as long as the two succeeding somites combined, whereas it is only about as long as these somites in M. helgolandica (see McAlice, 1985). A female specimen from the adjacent Ushuaia Bay, collected by Biancalana et al (2007) was examined and these differences were confi rmed. In light of (1) the general morphological resemblance of the male of M. patagonica n. sp.…”

“…to M. helgolandica, with the presence of pectinate antennules and the same type of genital lappets, (2) the differences from M. helgolandica in both sexes from Argentinian waters, (3) the close resemblance of females and males of M. helgolandica with other species (see Grygier and Ohtsuka, 1995), (4) the fact that only one such species has been recorded from the southern shores of Argentina, and (5) this being the only record of of Monstrilla males with pectinate antennules from the southern hemisphere, it is clear to us that the specimen depicted from this area more than 35 years ago (Ramírez, 1971) is the female of M. patagonica n. sp. Further, this species seems to be distributed in other coastal systems along the Beagle Channel, including Ushuaia Bay (Biancalana et al, 2007). In Bahia Blanca, Argentina, at the same general latitude range (42°S), records include Monstrilla sp., M. helgolandica, and M. aff.…”

“…In the Americas there are few records of Monstrilloida from high latitudes of the Southern hemisphere (i.e. Ramírez, 1971;Marín and Antezana, 1985;Dias, 2005;Suárez-Morales et al, 2006;Dias and Bonecker, 2007a, b;Biancalana et al, 2007;Hoffmeyer and Barría de Cao, 2007), and only two species have been hitherto reported from Subantarctic waters (Razouls, 1996).…”

“…The planktic copepods have long been studied in the South Atlantic but monstrilloids were not included (Bradford-Grieve et al, 1999). The only previous records of monstrilloids in the Beagle Channel are by Biancalana et al (2007), who reported Cymbasoma sp. and Monstrilla helgolandica Claus, 1863.…”

Seasonal and spatial variability of appendicularian density and taxonomic composition in the Caravelas Estuary (Northeastern Brazil) and adjacent coastal area

“…Studies on the distribution, specific composition, and abundance of appendicularians in oceanic regions of the southwest Atlantic have been carried out by several investigators, e.g., Lohmann (1896Lohmann ( , 1931, Lohmann and Buckmann (1926), Hentschell (1939), Fenaux (1967), Björnberg and Forneris (1956a, 1956b, 1958, Forneris (1965), Tundisi (1970), Esnal (1999), Campos (2000), and Bonecker and Carvalho (2006). Some studies have been carried out in coastal regions, where only species of the family Oikopleuridae (Bonecker et al, 1991;Vega-Pérez, 1993;Bonecker et al, 1998;Dias et al, 1999;Biancalana et al, 2005). In most studies of zooplankton, appendicularians have been treated only to class level (Navas, 1973;Montú, 1980;Nogueira et al, 1988;Lopes et al, 1998;Faro et al, 2000;Petrilho et al, 2005;Tsujimoto et al, 2006).…”