How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Growth Rates of Hawksbill Sea Turtles of the British Virgin Islands
Volume 17, Number 33: 13 August 2014

For the past several years, we have been bombarded with horror stories about the effects of CO2-induced warming and acidification of the world's oceans, which suggest that its animal life, as the saying goes, is "headed to hell in a handbasket." But is this really so?

The findings of a recently-completed study that was published in the scientific journal Ecology and Evolution suggest that we ought not be too quick to embrace the standard "doom and gloom" prognostications that are spewed out almost daily by the world's climate-alarmist establishment, as that group of enlightened ones tries to convince us that there is no good thing under the sun ... and especially under the planet's CO2-accreting atmosphere.

So what's the good news? ... and how did the scientists who did the research come to discover it?

Hawkes et al. (2014) write that "in the Caribbean, hawksbill sea turtles (Eretmochelys imbricata) were once abundant and supplied a global trade for 'tortoiseshell' (the attractive scute plates that make up the hawksbill turtles' carapace," citing Meylan (1999) and McClenachan et al. (2006)). But they say that "overharvest led to reduction in the Caribbean population, which is thought to remain at relictual levels today." And, therefore, they decided to determine the rate at which the remaining sea turtles are growing, in an attempt to determine the future viability of the species, which they did "using capture-mark-recapture of 59 turtles over periods of up to 649 days," wherein "turtles were recaptured up to six times, having moved up to 5.9 km from the release location." And what did they find?

Quoting the eight scientists involved in the study, "across all sizes, turtles grew at an average rate of 9.3 cm/year, and gained mass at an average of 3.9 kg/year." And they indicate that "these are among the fastest rates of growth reported for this species, with seven turtles growing at a rate that would increase their body size by more than half per year (51-69% increase)." In addition, they note that the implications of their study are such that "Caribbean hawksbill turtles in some areas may reach body sizes suggesting sexual maturity in less time than previously considered."

And to what do Hawkes et al. attribute these phenomenal rates of growth and development?

They say "it seems reasonable to hypothesize that fast growth rates on the Anegada shelf [at the northernmost extension of the British Virgin Islands] are fostered by extensive, sheltered, suitable habitat at warm temperatures with abundant and diverse forage food." And it would also seem reasonable to hypothesize that these environmental characteristics likely surpass in desirability those of past years, when the atmosphere's CO2 concentration was significantly less than what it is today.

Sherwood, Keith and Craig Idso

Hawkes, L.A., McGowan, A., Broderick, A.C., Gore, S., Wheatley, D., White, J., Witt, M.J. and Godley, B.J. 2014. High rates of growth recorded for hawksbill sea turtles in Anegada, British Virgin Islands. Ecology and Evolution 4: 1255-1266.

McClenachan, L., Jackson, J.B.C. and Newman, M.J.H. 2006. Conservation implications of historic sea turtle nesting beach loss. Frontiers in Ecology and the Environment 4: 290-296.

Meylan, A.B. 1988. Spongivory in hawksbill turtles: a diet of glass. Science 239: 393-395.