Showing papers in "Arquipelago : Life and Marine Sciences in 2009"

Presence of fibropapillomatosis in green turtles Chelonia mydas at Príncipe Island in the Gulf of Guinea

Abstract: Fibropapillomatosis is a transmissible and life threatening disease associated with one or more herpesviruses that are afflicting sea turtles worldwide (Herbst 1994). First documented on green turtles Chelonia mydas (Quackenbush et al. 1998), since the 1990's it has been found on other species, like hawksbills Eretmochelys imbricata (D’Amato & Moraes-Neto 2000; Williams & Bunkley-Williams 1996), olive ridleys Lepidochelys olivacea (Herbst 1994), loggerheads Caretta caretta (Aguirre 1998; Harms et al. 2008), and leatherbacks Dermochelys coriacea (Huerta et al. 2000). The etiology and prevalence of fibropapillomatosis are not fully understood and further research is needed. Even so, it is accepted that pelagic juveniles are free of the disease when recruiting to coastal foraging grounds (Ehrhart et al. 2000). Neritic juveniles and sub-adults appear to be the most affected lifehistory stages (George 1997; Murakawa et al. 2000), but the occurrence of the disease in adults is atypical (George 1997). There is evidence that the severity of the disease is correlated with the level of sea water pollution and rising temperature (Milton & Lutz 2003; Lafferty et al. 2004), abnormal clinical parameters (Aguirre & Balazs 2000) and immunosuppression (Work et al. 2001), as well as toxic cyanobacteria (Arthur el al. 2008) and/or marine-biotoxins (Landsberg et al. 1999) on the feeding areas. Aguirre & Lutz (2004) stated that the occurrence of fibropapillomas is not only an indicator of the sea turtle health, but also of the ecosystem health in the near-shore marine environment.

The study of bacterioplankton dynamics in the Berlengas Archipelago (West coast of Portugal) by applying the HJ-biplot method

Abstract: The relationship between bacterioplankton and environmental forcing in the Berlengas Archipelago (Western Coast of Portugal) were studied between February 2006 and February 2007 in two sampling stations: Berlenga and Canal, using an HJ-biplot. The HJ-biplot showed a simultaneous display of the three main metabolic groups of bacteria involved in carbon cycling (aerobic heterotrophic bacteria, sulphate-reducing bacteria and nitrate-reducing bacteria) and environmental parameters, in low dimensions. Our results indicated that bacterial dynamics are mainly affected by temporal gradients (seasonal gradients with a clear winter versus summer opposition), and less by the spatial structure (Berlenga and Canal). The yearly variation in the abundance of aerobic heterotrophic bacteria were positively correlated with those in chlorophyll a concentration, whereas ammonium concentration and temperature decreased with increasing phosphates and nitrites concentration. The relationship between aerobic heterotrophic bacteria, chlorophyll a and ammonium reveals that phytoplankton is an important source of organic substrates for bacteria.