The Variable Impact of Heinrich Events on the Benthic Environment of the Porcupine Abyssal Plain

Heinrich events (HEs) are Pleistocene climate disturbances caused by massive freshwater discharges from the Laurentide Ice Sheet via the Hudson Strait. They appear in marine sediments as layers of ice-rafted detritus (IRD) and significantly impact the benthic environment. While many studies focus on microorganisms, macrobenthic data from ichnological analysis are limited. HEs affect macrobenthic tracemaker communities in various ways, though a general pattern of gradual recovery is observed. However, regional factors strongly influence the environmental effects of HEs on tracemaker communities. In this study, we aim to go one step further and address the influence of these factors on the benthic realm at a short spatial scale. To this end, we investigate the ichnological characteristics of Heinrich Event 4 (H4) together with its geochemical data from three gravity cores taken less than 20 km apart in the Porcupine Abyssal Plain (NE Atlantic). One core is from a small abyssal hill (60 m high), and two from nearby abyssal plains. In the abyssal plains, H4 and subsequent IRD deposition led to the disappearance of trace fossils, with no gradual recovery—unlike previous findings. In contrast, the hill shows rapid recovery after IRD deposition. Geochemical data shows that productivity increased due to H4, which led to low oxygen conditions. We hypothesize that bottom currents along the hill flank improved seafloor oxygenation, enabling quicker recovery, while the plains remained poorly oxygenated. This study underscores how even minor seafloor topography can enhance the resilience of macrobenthic tracemaker communities during paleoclimatic events.