Two weeks ago MAE PhD candidate Erik Wurz started an experiment investigating the impact of suspended natural bottom sediment on the deep-sea sponge Vazella pourtalesi (Schmidt, 1870).
Vazella pourtalesi is a common habitat building sponge species in the North-West Atlantic Ocean, and one of the target species within the EU project SponGES. It can grow up to one meter in height and forms dense grounds on the continental shelf off the Canadian coast. Especially in the summer months a lot of fishery activities take place within the vicinity to these sponge grounds. Bottom gear is re suspending natural sediments and oceanic currents can spread these plumes over hundreds of kilometers. The experiments in Canada at the Bedford Institute of Oceanography (Halifax) focus on the influence these plumes of sediment might have on the filter-feeding sponges. Erik Wurz exposes individuals to a constant concentration of natural suspended sediment. Measurements of respiration rates, bacterial removal rates and nutrient uptake/excretion will reveal how the animals perform under these conditions. As the analysis of data and samples will take a while, luckily visual effects of the exposure treatment are already visible after a few days. The sponges turn brown and in the exhalent outflow from the oscula sediment particles are visible and show, that Vazella pourtalesi is still actively pumping under these conditions. It will be interesting to see how this might change with a longer exposure time.
Topview on treatment tanks (left control, right exposure) each treatment has five replicate tanks holding two animals, respectively.
Vazella pourtalesi in the control treatment without sediment exposure
Vazella pourtalesi individual in sediment exposure treatment after 2 days
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