associations with bacteria, filtering of the water column will enhance regeneration of nutrients there. Sponges can be regarded as natural filters which impact on water quality and can contribute significantly to benthic-pelagic coupling.” Collaborating with several research


groups that pursue interests in invertebrates


and ecosystems. benthic “We’re habitats,


Bannister’s work since 2010 has examined anthropogenic impacts on sponges and their


currently


undertaking several projects funded by the Norwegian Research Council. One examines the


impact of oil drilling activities on large aggregations of


also enabled the group to collect sponges from their habitats and bring them back to their lab, where they can be maintained and examined in the deep-sea ecology laboratory. These studies often involve simulating


local conditions to examine the response of common sponges to industrial activities, which can impact their habitats and disrupt their functioning. Bottom trawling along coastlines where sponges live stirs up natural sediments, creating plumes that


interact with them by


increasing the amount of suspended particles in the water. Mining, oil drilling and aquaculture may also affect


these


some 350,000 litres of water a day are pumped, the group has sought to accurately recreate


sponge communities. As their


facility is situated adjacent to a fjord, the scientists can pump water directly from their subjects’ original habitat to maintain them. This has enabled the Norwegian group to create extremely realistic simulated systems and preserve delicate species that are difficult to sustain in controlled


environments. During


experiments, sponges within the tanks were exposed to different types of sediment for a thirty-day period, and then given a one-month recovery period, during which their functions were assessed. One of the group’s main findings to date is


“We undertook extensive underwater video surveys to quantify the abundance of sponges, measure their sizes and see how they differed between locations”


sponges on the Norwegian continental shelf, while our other activities include looking at the functioning of sponges in fjord ecosystems and potential changes to these environments.” Nineteenth century anecdotes indicate


that fishermen used to retrieve large aggregations of sponges from the sea bed after trawling, but it is only now with modern technology that it has become possible to see what they look like in their natural habitat. “The development of remotely


operated underwater vehicles


(ROVs) in the late nineties, coupled with advances in video technology have enabled researchers to enter previously inaccessible environments,” says Bannister. “Some of the fjord habitats we are studying are at depths of between 150 and 300 metres. Using these technologies, we want to see if these ecosystems function similarly to other ecosystems.” Initially, explains Tina Kutti, a fellow


researcher at the Institute, the Bergen team sought to obtain quantitative details of the sponge populations. “We undertook extensive underwater video surveys to quantify the abundance of sponges, and measure their sizes and how they differed between locations,” she says. “Using this information, we constructed a picture of their wider aggregations, and created a database from which to extrapolate their importance.” Deploying ROV equipment


www.projectsmagazine.eu.com 53


environments different


through sediment sponges types, utilise,


generating discharges,


pollutants and dumping. The researchers have thus been looking at the natural sediment


how they


process it, and their ability to cope with changes. These studies will also look at scenarios such as the impact of multiple stressors, by combining different degrees of


sedimentation with varying


temperatures and ocean acidification, to understand how this affects the sponges and the wider ecosystem. Using laboratory tanks with volumes of between 50 and 600 litres, through which


©Photo:IMR


that cold-water sponges are highly efficient filter feeders and important contributors to benthic-pelagic coupling. The researchers were able to elucidate


their roles as consumers of bacteria and dissolved nutrients, which will have beneficial flow-on effects to neighbouring organisms. “Our studies of suspended sediment thresholds were also very insightful,” reports Bannister. “We found that different types of sediment can influence the physiological and cellular functioning of sponges, with particle composition, size and concentration


important influencing their factors responses. Moreover,


they may also influence the distribution of species. Different types of sponges occupy very


different environments,


which vary between highly sedimented regions and non-sedimented areas, and each sponge species has distinct environmental requirements.” Sediments can act as agents that stimulate sponge morphology and encourage them to


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