The response of Nonionella iridea and other benthic foraminifera to “fresh” organic matter enrichment and physical disturbance

Coastal primary productivity changes over the last millennium: a case study from the Skagerrak (North Sea)

“…At the same time, a clear dominance of the P. osloensis factor including species P. osloensis and N. iridea, with an addition of C. laevigata in EMB046/10-4GC is documented throughout, in line with the previously identified C. laevigata -P. osloensis cluster (ErbsHansen et al, 2011) and N. iridea -C. laevigata category (Alve, 2010). These three species have an ecological preference for nutrient-rich environments, preferably with oxic bottom water conditions (Alve, 2003(Alve, , 2010Duffield et al, 2015). Hence, 25 overall nutrient-rich conditions likely prevailed in the Skagerrak.…”

“…In EMB046/20-3GC, the C. laevigata is largely replaced by 15 dominance of N. iridea which is commonly present in the Skagerrak and the Scandinavian fjord waters with a salinity >35 PSU and a temperature range of 6 -6.5 °C (Polovodova Asteman et al, 2013 and references therein). In addition, N. iridea is capable of growth under hypoxic-suboxic conditions (Duffield et al, 2015). Hence the dominance of N. iridea over C. laevigata in EMB046/20-3GC may be related to the less favourable bottom water oxygen conditions due to the lower contribution of well-oxygenated Atlantic waters to the central Skagerrak than in its western part.…”

“…Conradsen et al, 1994;Murray, 1995, 1997;Alve, 2003;Gustafsson and Nordberg, 2001;Duffield et al, 2015). The absolute abundance of planktonic foraminifera, stable carbon isotopes and total organic carbon also inform on past variability of productivity.…”

“…The B. skagerrakensis factor relates to ecological preferences of the epifaunal to shallow infaunal benthic species B. skagerrakensis, a species 20 associated with high fresh phytodetritus fluxes to the sea floor accompanied by a continuously high oxygen content in the sediments (Duffield et al, 2015). The abundant occurrence of B. skagerrakensis in the Skagerrak and Oslofjord area is restricted to water masses with temperatures between 5 and 7 °C and salinity around 35 PSU (Qvale and Nigam, 1985 and references therein;Murray, 1995, 1997;Duffield et al, 2015). In contrast to P. osloensis, N. iridea and C. laevigata, taxon B. skagerrakensis does not feed on decaying organic matter but prefers freshly settled algal material (Duffield et al, 25 2015).…”

“…4). Generally lower organic 5 fluxes indicated by the lower TOC values in core EMB046/10-4GC (Fig 5), might have caused a food-competitive environment where the herbivorous B. skagerrakensis was likely outcompeted by a more omnivorous to detritivorous species C. laevigata, P. osloensis and N. iridea, which are all able to feed on both fresh and decaying organic matter (Alve, 2010;Duffield et al, 2015).…”