Climatic forcing of Quaternary deep-sea benthic communities in the North Pacific Ocean

Abstract

There is growing evidence that changes in deep-sea benthic ecosystems are modulated by climate changes, but most evidence to date comes from the North Atlantic Ocean. Here we analyze new ostracod and published foraminiferal records for the last 250,000 years on Shatsky Rise in the North Pacific Ocean. Using linear models, we evaluate statistically the ability of environmental drivers (temperature, productivity, and seasonality of productivity) to predict changes in faunal diversity, abundance, and composition. These microfossil data show glacial-interglacial shifts in overall abundances and species diversities that are low during glacial intervals and high during interglacials. These patterns replicate those previously documented in the North Atlantic Ocean, suggesting that the climatic forcing of the deep-sea ecosystem is widespread, and possibly global in nature. However, these results also reveal differences with prior studies that probably reflect the isolated nature of Shatsky Rise as a remote oceanic plateau. Ostracod assemblages on Shatsky Rise are highly endemic but of low diversity, consistent with the limited dispersal potential of these animals. Benthic foraminifera, by contrast, have much greater dispersal ability and their assemblages at Shatsky Rise show diversities typical for deep-sea faunas in other regions. Statistical analyses also reveal ostracod-foraminferal differences in relationships between environmental drivers and biotic change. Rarefied diversity is best explained as a hump-shaped function of surface productivity in ostracods, but as having a weak and positive relationship with temperature in foraminifera. Abundance shows a positive relationship with both productivity and seasonality of productivity in foraminifera, and a hump-shaped relationship with productivity in ostracods. Finally, species composition in ostracods is influenced by both temperature and productivity, but only a temperature effect is evident in foraminifera. Though complex in detail, the global-scale link between deep-sea ecosystems and Quaternary climate changes underscores the importance of the interaction between the physical and biological components of paleoceanographical research for better understanding the history of the biosphere.

Is the meiofauna a good indicator for climate change and anthropogenic impacts?

“…The Ostracoda fossil record is of greatest value for tracing palaeo-climate events, providing valuable information on past water salinity, temperature and chemistry, hydrodynamic conditions, substrate characteristics, climate, sea level variations, oxygen and nutrient availability (Frenzel and Boomer 2005) and anthropogenic influences (Irizuki et al 2015). Yasuhara et al (2012aYasuhara et al ( , 2014 used ostracod and foraminiferal fossil records from the last 250,000 years on the Shatsky Rise in the North Pacific Ocean to demonstrate that rapid climate changes affect deep-sea benthic diversity. They observed glacial-interglacial shifts in overall abundances and species diversities for both meiofauna taxa.…”

Biodiversity–ecosystem functioning relationships in long-term time series and palaeoecological records: deep sea as a test bed

“…Indeed, environmental (temperature and POC flux) impacts on deep-sea species diversity and microfossil accumulation rate (here we used this as a proxy for biomass, i.e. ecosystem functioning) are well described [36,62,65,67,69]. Microfossil accumulation rate is a proxy for POC flux [47,69] and here we used it as a proxy for ecosystem function.…”

“…ecosystem functioning) are well described [36,62,65,67,69]. Microfossil accumulation rate is a proxy for POC flux [47,69] and here we used it as a proxy for ecosystem function. Manipulative BEF experiments usually look into biodiversity effects on ecosystem function, whereas this palaeoobservational study investigated correlations between these effects, which are usually interpreted as POC-flux impact on biodiversity.…”

Calcareous microfossil-based orbital cyclostratigraphy in the Arctic Ocean

“…Although too numerous to review, benthic foraminiferal assemblages have been shown to be linked to surface ocean productivity (Gooday, 1988) and the benthic foraminiferal accumulation rate (BFAR) index has been used as a tool to investigate glacial-interglacial changes in ocean productivity (Herguera and Berger, 1991;Herguera, 2000) (see Gooday, 2003;Jorissen et al, 2007 for reviews). Ostracode species diversity is also correlated to POC variability over orbital timescales (Yasuhara et al, 2012).…”