marine ecosystems

water masses

deep sea

regime shifts

Frontiers in Marine Science

&lt;p&gt;Circulation patterns in the North Atlantic Ocean have changed and re-organized multiple&lt;br&gt; times over millions of years, influencing the biodiversity, distribution, and connectivity&lt;br&gt; patterns of deep-sea species and ecosystems. In this study, we review the effects&lt;br&gt; of the water mass properties (temperature, salinity, food supply, carbonate chemistry,&lt;br&gt; and oxygen) on deep-sea benthic megafauna (from species to community level) and&lt;br&gt; discussed in future scenarios of climate change. We focus on the key oceanic controls&lt;br&gt; on deep-sea megafauna biodiversity and biogeography patterns. We place particular&lt;br&gt; attention on cold-water corals and sponges, as these are ecosystem-engineering&lt;br&gt; organisms that constitute vulnerable marine ecosystems (VME) with high associated&lt;br&gt; biodiversity. Besides documenting the current state of the knowledge on this topic,&lt;br&gt; a future scenario for water mass properties in the deep North Atlantic basin was&lt;br&gt; predicted. The pace and severity of climate change in the deep-sea will vary across&lt;br&gt; regions. However, predicted water mass properties showed that all regions in the North&lt;br&gt; Atlantic will be exposed to multiple stressors by 2100, experiencing at least one critical&lt;br&gt; change in water temperature (C2C), organic carbon fluxes (reduced up to 50%), ocean&lt;br&gt; acidification (pH reduced up to 0.3), aragonite saturation horizon (shoaling above 1000&lt;br&gt; m) and/or reduction in dissolved oxygen (&gt;5%). The northernmost regions of the North&lt;br&gt; Atlantic will suffer the greatest impacts. Warmer and more acidic oceans will drastically&lt;br&gt; reduce the suitable habitat for ecosystem-engineers, with severe consequences such&lt;br&gt; as declines in population densities, even compromising their long-term survival, loss of&lt;br&gt; biodiversity and reduced biogeographic distribution that might compromise connectivity&lt;br&gt; at large scales. These effects can b...

Influence of Water Masses on the Biodiversity and Biogeography of Deep-Sea Benthic Ecosystems in the North Atlantic