Browsing by Author "Claro, B."
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- Major shifts at the range edge of marine forests: the combined effects of climate changes and limited dispersalPublication . Assis, J.; Berecibar, E.; Claro, B.; Alberto, F.; Reed, D.; Raimondi, P.; A, SerrãoGlobal climate change is likely to constrain low latitude range edges across many taxa and habitats. Such is the case for NE Atlantic marine macroalgal forests, important ecosystems whose main structuring species is the annual kelp Saccorhiza polyschides. We coupled ecological niche modelling with simulations of potential dispersal and delayed development stages to infer the major forces shaping range edges and to predict their dynamics. Models indicated that the southern limit is set by high winter temperatures above the physiological tolerance of overwintering microscopic stages and reduced upwelling during recruitment. The best range predictions were achieved assuming low spatial dispersal (5 km) and delayed stages up to two years (temporal dispersal). Reconstructing distributions through time indicated losses of similar to 30% from 1986 to 2014, restricting S. polyschides to upwelling regions at the southern edge. Future predictions further restrict populations to a unique refugium in northwestern Iberia. Losses were dependent on the emissions scenario, with the most drastic one shifting similar to 38% of the current distribution by 2100. Such distributional changes might not be rescued by dispersal in space or time (as shown for the recent past) and are expected to drive major biodiversity loss and changes in ecosystem functioning.
- Performing fish counts with a wide-angle camera, a promising approach reducing divers' limitationsPublication . Assis, J.; Claro, B.; Ramos, Ana; Boavida, Joana; Serrão, EsterVisual standardised methods for census of reef fishes have long been used in fisheries management and biological surveys. However, these tools have inherent sources of bias and the SCUBA divers who perform them are highly constrained in terms of survey time,maximumdepth and frequency of sampling. Alternatives like underwater video are thus being recommended in a wide range of configurations. Yet, all these techniques are still limited in field of view, particularly when compared to the ability of a SCUBA diver performing censuses. In this scope, we evaluated the potential of an underwater wide-angle camera (UWC) to survey fish assemblages by testing it against instantaneous underwater visual census (UVC). Our results showed minimal yet significant differences between methods, mainly because of the camera's loss of resolution when under extreme visibility conditions. Both approaches had the same consistency and ability to detect changes in fish assemblages but, to estimate total species richness, the UWC needed less field effort. Moreover, a SCUBA diver performing census had an effect on fish assemblages which introduced differences of greater magnitude than those found between methods. The removal of the diver effect, the proven ability to detect changes in fish assemblages and the verified gain in field effort, pointed the wide-angle camera as a promising tool to perform census of reef fishes.