Recruitment of Arctic deep‐sea invertebrates: Results from a long‐term hard‐substrate colonization experiment at the Long‐Term Ecological Research observatory HAUSGARTEN

Abstract

AbstractFor benthic marine invertebrates, recruitment strongly influences the composition and abundance of resulting communities. We present the results of a long‐term (1999–2017) colonization experiment at the Long‐Term Ecological Research observatory HAUSGARTEN in the Fram Strait (Arctic Ocean, 79°N, 04°E, 2500 m water depth). Recruitment panels were constructed from plastic and brick and deployed attached to a metal frame in 1999. The experiment was monitored using a remotely operated vehicle in 2003 and 2011 and recovered in 2017. Recruitment was very low, with only foraminiferans being visible after 4 yr (2003) and one metazoan species, the hydroid Halisiphonia arctica, being visible on the panels after 12 yr (2011). After 18 yr underwater, panels were colonized by 13 metazoan species as well as calcareous and agglutinating foraminiferans. Recruitment was higher on brick panels than on plastic, but while some species were more common on panels at higher altitude (H. arctica and the crinoid Bathycrinus carpenterii), others were more common on panels closer to the seafloor (serpulid polychaetes) or on panels in line with the predominant bottom current (small round white sponges). The most common species recruiting to our panels can be described as opportunistic. Meanwhile, large hexactinellid sponges that are common in natural communities did not recruit to our panels. These results suggest that community assembly in the Arctic deep sea takes much longer than the two decades spanned by this study.