Marine species subjected to high CO2 extremes – 8,891 to 95,000 ppm – in their natural environments may not be adversely affected. They may even “thrive”.
Earlier this year we highlighted a study that says coral reefs “thrive” near seafloor volcanic vents where CO2 concentrations reach 60,000 to 95,000 ppm.
Image Source: PHYS.ORG
Urchins basking in volcanic vent streams of 8,891 ppm CO2 and daily CO2 variations of more than 2,000 ppm as well as day-to-day pH fluctuations ranging from 6.9 (“acidification”) to 8.1…grow more than two times faster than nearby control (stable 394 ppm CO2, 8.1 pH) urchins (Uthicke et al., 2016).
Image Source: Uthicke et al., 2016
According to a new study, corals “were observed to persist within acidified [<7 U] waters”, with pH lows reaching as low as 6.5 (Enochs et al., 2020). This effectively means corals can endure any doomsday “ocean acidification” scenario allegedly linked to human fossil fuel burning.
“Herein, we have characterized an area of volcanic acidification at Mayreau Island, St. Vincent and the Grenadines. Despite localized CO2 enrichment and gas venting, the surrounding area has high hard and soft coral cover, as well as extensive carbonate frameworks. Twice daily extremes in acidification [with pH levels as low as 6.540], in some cases leading to undersaturation of aragonite, are correlated with tidal fluctuations and are likely related to water flow. Corals persisting despite this periodic acidification can provide insights into mechanisms of resilience and the importance of natural pH variability on coral reefs.”
“To date, natural acidification hotspots have been identified corresponding to upwelling (Manzello 2010), submarine groundwater discharge (Crook et al. 2013), and biological activity (Shamberger et al. 2014), as well as volcanic CO2 seeps.”
“At Mayreau, as with the sites in New Caledonia, corals were observed to persist within acidified waters, potentially indicating mechanisms of resilience to extreme acidification stress.”
June 29, 2020 at 12:07PM