ALBERT

Description: Species are lost with accelerating speed all over the world. (Edwards and Abivardi 1998). Each species that is lost reduces the diversity of the global ecosystem. However, diversity is known to be important for the functioning of ecosystems (Giller and O'Donovan 2002). The IDH (intermediate disturbance hypothesis) and a model developed by Kondoh (2001) predict the influence of disturbance on diversity (IDH) and of the interactive effect of disturbance and productivity on diversity (Kondoh 2001). Although the IDH is one of the most frequently used models to explain the disturbance-diversity-relationship, there has been little evidence for its validity (Mackey and Currie 2000). In order to test the validity of both models, the influence of disturbance and productivity on the diversity of marine hard-bottom communities was investigated at two sites at the north-west coast of Italy in an experimental in-situ approach. Seven levels of disturbance frequency, i.e. removal of biomass, were fully crossed with three levels of nutrient concentration in an orthogonal design. Species richness was significantly influenced by the interaction between the two factors, but the disturbance-productivity-diversity-relationship that is predicted by Kondoh (2001) was not observed. Neither productivity, nor disturbance, nor their interaction influenced total cover or evenness of the communities. Separately analysed taxa proved that disturbance influenced their abundance, while productivity had no measurable influence. In conclusion, due to the results of this study and to the results of eight twin experiments conducted all over the world, neither the IDH, nor the model developed by Kondoh (2001) are sufficient to explain the ecological processes that influence diversity.

Description: A system is presented which uses a Hall sensor and an adjacent magnet, attached close to the cloaca of penguins, to record defecation, respiration and heart rates for both free-living birds and those in captivity. The output of the Hall sensor depends on a magnetic field, the strength of which is influenced in the presented scenario by the proximity of the magnet, which varies with movement of the cloaca. The elasticity of the cloaca results in minute, but perceptible, movements associated with the heart, respiration and defecation, although placement of the magnet and sensor is critical, and not all parameters can be measured all of the time. The system, incorporating a logger that can record at frequencies of 50 Hz, was tested on 17 captive and 4 freeliving Magellanic penguins, Spheniscus magellanicus, in Argentina. It showed increased defecation rate associated with feeding, the expected trends in bradycardia and tachycardia associated with diving, and appeared to record some movement of air sacs associated with breathing. The concept of measuring minute changes in relative exterior body positions as a cue to internal processes may be important in future studies for both free-living and captive animals, particularly since it is non-invasive and relatively easy to deploy.