Cold water corals grow under future pH conditions in situ

• Main Authors: Jantzen, Carin, Häussermann, Verena, Försterra, Günter, Laudien, Jürgen, Richter, Claudio
• Format: Conference Object
• Language: unknown
• Published: 2012
• Subjects: Ocean acidification
• Online Access: https://epic.awi.de/id/eprint/26114/; https://hdl.handle.net/10013/epic.39024

Ocean acidification (OA) caused by the anthropogenic induced climate change via increasing CO2 release may be one of the main threats to the marine realm. OA will be a challenge to most marine calcifiers, but cold water corals are thought to be particularly affected owing to the nature of their cold and often deep habitat. The ‘Fjordo Comau’ (Chilean Patagonia) already today exhibits pCO2 values that are predicted for the year 2100 in the IPCC scenarios, comprising pH gradients up to 0.6 within the first? 225 m. Nevertheless, the ubiquitous cold water coral Desmophyllum dianthus thrives apparently unimpaired along these gradients. It forms dense banks along the fjord and moreover occurs as a member of a deep water emergence community as shallow as 12 m. Herein we present results of an in situ experiment cross-transplanting corals between two sites with a pH difference of ~ 0.15 (pH of 7.93 ± 0.09 and 7.78 ± 0.11). Growth was measured with the buoyancy weight method and two weeks were sufficient to show clear weight increase, still rates were relatively variable (5.75 ± 3.26 [mg CaCO3 cm-2 d-1] and 0.29 ± 0.19 [% d-1]). No differences of short-term growth rates between the two sites could be detected. Either there are factors that outbalance the adverse effects of low pH and/or cold water corals in general or Desmophyllum dianthus in particular may have a great ability to acclimatize or even adapt to a broad range of environmental conditions including pH. Nevertheless there may be limiting boundaries that restrict distribution, especially in the future when pH values will further decline.