BIOACID Programme - Natural Environment Research Council

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BIOACID: Biological Impacts of Ocean Acidification
open ocean flow through seawater and rely on recirculated aquaria with a water treatment
section. This includes the large recirculated aquarium system at AWI Bremerhaven, funded by
BMBF upon the unification of AWI and BAH.
Oxidative catabolism of heterotrophs is characterized by net proton production (Pörtner 1995)
which is compensated for by ion exchange mechanisms and leads to a net release of protons into
the water with the result of disturbed physicochemical parameters at constant or falling DIC (the
latter occurs once excess CO2 generated by titration of (bi)carbonate is released into the
atmosphere). Furthermore, any delay in the equilibration of air or gas mixtures with the aquarium
water will prevent precise analysis of relevant water physicochemistry and thus sabotage any
efforts to maintain constant settings of relevant parameters. The goal of this development must
therefore be to monitor the effects of non-respiratory proton loads to the system water under
equilibrium conditions and to compensate for any pH disturbance resulting from net proton
equivalent ion exchange by aquarium maintained organisms.
Rearing of larvae of crustaceans, cephalopods and fishes (esp. cod) also needs to be carried out in
recirculated aquarium systems under largely undisturbed conditions. These activities will make
the putative most sensitive life stages available for studies of effects of ocean acidification.
Rearing would ideally occur under control vs. elevated CO2 conditions. The proposed system is a
miniaturized AquaInno Pond-in-Pond system for hatchery developed by AWI and IMARE (R.
Fisch, B.H. Buck). It offers a “system within a system” approach by providing process water with
additional purification and water exchange on demand, without disturbing sensitive life stages.
Modification and change of modules is possible and support a wide range of experiments. The
system can be isolated from air and ambient water for equilibration with various CO2 levels.
During long term incubations repeated water exchange is feasible in the pH stabilized
recirculated large scale aquarium systems (see above).
Fig. 0.2 (1): Draft of the floating AquaInno nearshore technology illustrating its components for water treatment. The
waste water flows from the fish sector (A) to a first waste collector (B), where particles will sediment in the tubes
system. A following bioreactor (C) eliminates dissolved nitrogen and phosphate. The re-use of water is controlled by
sensors (G) and sediment disposal (F) takes place. A pneumatic system simplifies handling and harvesting (E) of
cultured organisms. The platform (D) around the culture module is improving the overall handling of the system.
Surrounding algal cultures (I) eliminate the final product nitrate. D and I are not included for indoor use.
Fig. 0.3 (2): First freshwater prototype of a floating in pond raceway used for cultivation of ornamental fish in the year
2004. Currently, the system is developed for hatchery and grow-out in seawater and has been modified as a
recirculation system with different modules.
For CO2 equilibration according to IPCC emission scenarios large temperature controlled
experimental chambers have to be maintained at constant CO2 partial pressures according to gas
mixtures provided by commercial suppliers. A prototype developed by AWI (B. Klein) needs to