Estamos agora a caminho de uma área mais fascinante dos Oceano, a Frente Polar Antártica (onde as águas frias do Oceano Antártico se juntam às águas mais quentes a norte), no congelador já temos amostras muito interessante, da Geórgia do Sul, que nos vão ajudar a perceber como funciona a cadeia alimentar Antártica. Em particular, o impacto que os de metais pesados podem ter no ecossistema marinho desta região da Antártida. Recolhemos desde amostras de água, a peixes e lulas, passando por diversas espécies de zooplâncton.
A água, recolhidas pelo equipamento CTD (que regista dados de condutividade, temperatura e densidade da água a diferentes profundidades), vai nos dar um valor base de contaminação para esta região. Recolhemos alguma das espécies de camarão (ex. Euphausia superba, Euphausia frigida, Euphausia triacantha e Themisto gaudichaudii), lulas (Galiteuthis glacialis, Psycroteuthis glacialis, Sloczarcykovia circumantarctica) e de peixes (ex. Gymnoscopelus braueri, Gymnoscopelus nicholsi e Protomyctophum bolini) mais abundantes nesta região foram recolhidas durante a Western Core Box (uma área de estudo importante há muitos anos junto à Geórgia do Sul). Recolhemos estas amostras utilizamos diferentes tipos de rede, normalmente à noite pois é mais fácil capturar, pois os animais não conseguem ver a rede: quanto menor a malhagem (tamanho dos buracos da rede), mais pequenos são os organismos.
Assim, usamos as RMT8 (Arrastro retangular pelágico, o que significa basicamente uma rede retangular que tenta apanhar animais no meio da (coluna de) água) principalmente para os camarões ou zooplâncton (pequenos organismos marinhos). Com a rede RMT25, com malhagem maior, esperamos apanhar mais peixe e lulas. No primeiro dia deste ano novo tivemos o privilégio de apanhar uma lula muito especial, Histioteuthis (or Sigmatoteuthis) eltaninae.
Também temos a cientista Angelika Slomska (Polónia) que está interessada em Salpas (organismo gelatinoso chamada Salpa thompsoni) que ainda se conhece pouco... como podem concluir, as nossas noites são extremamente ocupadas, mas sempre muito interessantes!!!! Agora na Frente Polar espera-mos encontrar mais abundância de animais e espécies completamente diferentes. Entusiasmo é grande!!!! Fica em contato para mais notícias em breve!
We already have a nice group of samples, collected close to South Georgia, to study the Antarctic marine food web, particularly the role of heavy metals in it. The water samples (collected by the equipment called CTD (that measures conductivity, temperature and density and different depths) and different organisms such as the crustaceans (e.g. Euphausia superba, Euphausia frigida, Euphausia triacantha e Themisto gaudichaudii) and fish (e.g. Gymnoscopelus braueri, Gymnoscopelus nicholsi e Protomyctophum bolini) were already obtained at the Western Core Box (an important study area for many years, with numerous cruises of the British Antarctic Survey, close to South Georgia). To obtain these samples we use a wide range of nets, usually at night, when the it is easier to capture the organisms (as numerous species migrate closer to the surface at night). For our research, we use RMT8 (Rectangular Midwater Trawl, with smaller mesh) that can sample the water column very well for zooplankton (e.g. Antarctic krill). The RMT25, which is bigger (with bigger mesh), can also catch faster fish and squid. On the first day of the year, we had the privilege of catching a very special squid, Histioteuthis (or Sigmatoteuthis) eltaninae. I have known this squid for 20 years, but only through their beaks (i.e. the mandibles of the squid) found in the diet of penguins, seals and albatrosses. Finally, I was able to see a complete individual of Histioteuthis eltaninae! I am so happy. It is beautiful! It has photophores around its body, including around its eyes. Interesting enough, one eye is considerably bigger than the other. This is probably to this squid live predominantly in deep waters ( more than 200 meters depth) where the sunlight does not reach. Therefore, having 1 big eye could give an advantage to find prey, find partners and avoid predation. Big smile on our faces!!! All the samples collected are of particular interest, beyond us, to our colleague scientists Ryan Saunders, Sophie Fielding, Stacey Dornan, Rob Blackwell (UK) e Gabi Stowasser (Germany), that also are doing research projects on some of these species. Other research teams are also using other nets: BONGO, MUDL e MOCNESS (all with small mesh) can be used in shallow and deep waters, excellent to catch small zooplankton alive and in good conditions (useful to the scientists Geraint Tarling and Vicky Fowler (UK), Clara Manno e Elisa Bergami (Italy)). We also have the scientist Angelika Slomska (Poland) that is interested in Salps (gelatinous organism called Salpa thompsoni) that is still poorly known but its importance in the Southern Ocean has recently been recognized...as you can conclude, our night have been busy since the new years eve!!! Now we are on our way to another research station in one of the most fascinating ocean areas of the Southern Ocean, the Antarctic Polar Front (where cold water from the Antarctic get together with the warmer waters from the north) where we hope to find a mix of species from Antarctic and sub-Antarctic waters and assess the gradient of trophic interactions and trace levels in this area. Our enthusiasm is high!!!! Keep log on for more news soon...
Sem comentários:
Enviar um comentário