Responses of an abyssal meiobenthic community to short-term burial with crushed nodule particles in the south-east Pacific
Mevenkamp, L.; Guilini, K.; Boetius, A.; De Grave, J.; Laforce, B.; Vandenberghe, D.; Vincze, L.; Vanreusel, A. (2019). Responses of an abyssal meiobenthic community to short-term burial with crushed nodule particles in the south-east Pacific. Biogeosciences 16(11): 2329-2341. https://doi.org/10.5194/bg-16-2329-2019
Increasing industrial metal demands due to rapid technological developments may drive the prospection and exploration of deep-sea mineral resources such as polymetallic nodules. To date, the potential environmental consequences of mining operations in the remote deep sea are poorly known. Experimental studies are scarce, especially with regard to the effect of sediment and nodule debris depositions as a consequence of seabed mining. To elucidate the potential effects of the deposition of crushed polymetallic nodule particles on abyssal meiobenthos communities, a short (11 days) in situ experiment at the Peru Basin in the South East Pacific Ocean was conducted. We covered abyssal, soft sediment with approx. 2cm of crushed nodule particles and sampled the sediment after eleven days of incubation at 4200m water depth. Short-term ecological effects on the meiobenthos community were studied including changes in their composition and vertical distribution in the sediment as well as nematode genus composition. Additionally, copper burden in a few similar-sized, but randomly selected nematodes was measured by means of µ-X-ray fluorescence. At the end of the experiment, 46±1% of the total meiobenthos occurred in the added crushed nodule layer while abundances decreased in the underlying 2cm compared to the same depth-interval in original, undisturbed sediments. Densities and community composition in the deeper 2–5cm layers remained similar in covered and undisturbed sediments. The migratory response into the added substrate was particularly seen in polychaetes (73±14%, relative abundance across all depth layers) copepods (71±6%), nauplii (61±9%) and nematodes (43±1%). While the dominant nematode genera in the added substrate did not differ from those in underlying layers or the undisturbed sediments, feeding type proportions in this layer were altered with a 9% decrease of non-selective deposit feeders and an 8% increase in epistrate feeders. Nematode tissue copper burden did not show elevated copper toxicity resulting from burial with crushed nodule particles. The results indicate that short-term substrate burial requires special attention with regard to ecological consequences of mineral extraction in the deep-sea.
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