Prediction of unprecedented biological shifts in the global ocean

Abstract

Impermanence is an ecological principle 1 involving changes that can sometimes occur non-linearly as Abrupt Community Shifts (ACSs) to transform ecosystem states and the goods and services they provide 2. Here, we present a model based on niche theory 3 to explain and predict ACSs at the global scale. We test our model using 14 multi-decadal time series of marine metazoans from zooplankton to fish, spanning all latitudes and the shelf to the open ocean. Predicted and observed fluctuations correspond, with both identifying ACSs at the end of the 1980s 4-7 and 1990s 5,8. We show that these ACSs coincide with changes in climate that alter local thermal regimes, which in turn interact with the thermal niche of species to trigger long-term and sometimes abrupt shifts at the community level. A large-scale ACS is predicted after 2014-unprecedented in magnitude and extent-coinciding with a strong El Niño event and major shifts in Northern Hemisphere climate. Our results underline the sensitivity of the Arctic Ocean, where unprecedented melting may reorganize biological communities 5,9 and suggest an increase in the size and consequences of ACS events in a warming world. Main text The processes that cause long-term changes and Abrupt Community Shifts (ACSs) in ecosystems are poorly understood despite decades of research 2,4,10-12. We define an ACS as a stepwise shift in community structure 12 , a definition that does not necessarily imply the existence of stable states 2,10 ,

Climate change undermines the global functioning of marine food webs

“…can be assumed to be caused by the effects of constant fishing catch over already exploited system and the growing effect of ocean warming (Beaugrand et al, 2019). In parallel, the decreasing trend in BRT between 1950 and the mid-1990s is consistent with the observed BRT (Figure 6b).…”

Warm Events Induce Loss of Resilience in Organic Carbon Production in the Northeast Pacific Ocean

“…A model-based approach predicted that the marine community composition would shift ecologically during the warm events considered here (Beaugrand et al, 2019). A model-based approach predicted that the marine community composition would shift ecologically during the warm events considered here (Beaugrand et al, 2019).…”

“…The time lag between the ocean's physical response (i.e., SSTa, SLPa, and MLDa) and the consequences to primary producers, net organic carbon production, and, ultimately, higher food webs illustrates the connectivity and feedbacks within the ecosystem. A model-based approach predicted that the marine community composition would shift ecologically during the warm events considered here (Beaugrand et al, 2019).…”

Faster Atlantic currents drive poleward expansion of temperate phytoplankton in the Arctic Ocean

“…In addition, a change toward temperate pelagic species could have an impact on energy transfer to higher trophic levels 65 including marine mammals and commercial fish stocks 66 . Considering the role of "bio-advection" in ecological models (i.e., trait-based and niche-based approaches) must improve predictions of community shifts 67 . The comparable increase in poleward advection of Pacific waters occurring in the Bering Strait 68 suggests that the shrinking polar domain of the Arctic Ocean may be prone to intrusions of temperate species at a pan-Arctic scale.…”