Short-Term Response of Deep-Water Benthic Megafauna to Installation of a Pipeline Over a Depth Gradient on the Angolan Slope

Large structures are introduced into deep-water marine environments by several industrial activities, including hydrocarbon exploitation. Anthropogenic can alter ecosystem structure and functioning in many ecosystems but the responses on continental margins poorly known. Here, we investigate short-term response of benthic megafauna to installation a 56 km-long 30 cm diameter pipeline Angolan Margin (Block 31) from 700 1800 m water depth using remotely operated vehicle imagery. Clear depth-related patterns exist density, diversity community observed 2013 prior installation. These altered subsequent survey 2014, three-months after Significant increases particularly mid-slope regions observed. Diversity is generally, not consistently, enhanced, shallower areas 2014. changes noted between years. primarily caused abundance echinoderms, echinoid Phormosoma sp. indet. There was no evidence colonisation three months visible fauna. The few large anemones attached pipe may be able move as adults. appeared trap organic material anthropogenic litter, enhance available food resources locally well providing hard substratum. results indicate complex ecosystem-dependent caution against simplistic approaches environmental management.