Temporal changes in deep-sea sponge populations are correlated to changes in surface climate and food supply

► Two sponge species were studied in 18 years of transects from abyssal Station M. ► Both density and size were correlated for the two species, indicating similar niches. ► Density correlated negatively with average size; related to reproduction or growth. ► Plate sponge density correlated positively with POC flux with a 13-month time lag. ► Populations fluctuated with changes in surface climate indices (NOI and NPGO).