MEPS 543:127-140 (2016)  -  DOI: https://doi.org/10.3354/meps11568

ABSTRACT: Global climate change involves an increase in oceanic CO₂ concentrations as well as thermal stratification of the water column, thereby reducing nutrient supply from deep to surface waters. Changes in inorganic carbon (C) or nitrogen (N) availability have been shown to affect marine primary production, yet little is known about their interactive effects. To test for these effects, we conducted continuous culture experiments under N limitation and exposed the bloom-forming dinoflagellate species Scrippsiella trochoidea and Alexandrium fundyense (formerly A. tamarense) to CO₂ partial pressures ( pCO₂) ranging between 250 and 1000 µatm. Ratios of particulate organic carbon (POC) to organic nitrogen (PON) were elevated under N limitation, but also showed a decreasing trend with increasing pCO₂. PON production rates were highest and affinities for dissolved inorganic N were lowest under elevated pCO₂, and our data thus demonstrate a CO₂-dependent trade-off in N assimilation. In A. fundyense, quotas of paralytic shellfish poisoning toxins were lowered under N limitation, but the offset to those obtained under N-replete conditions became smaller with increasing pCO₂. Consequently, cellular toxicity under N limitation was highest under elevated pCO₂. All in all, our observations imply reduced N stress under elevated pCO₂, which we attribute to a reallocation of energy from C to N assimilation as a consequence of lowered costs in C acquisition. Such interactive effects of ocean acidification and nutrient limitation may favor species with adjustable carbon concentrating mechanisms and have consequences for their competitive success in a future ocean.

KEY WORDS: Dinoflagellates · Ocean acidification · Nitrogen limitation · Paralytic shellfish poisoning · PSP toxins

Full text in pdf format

Cite this article as: Eberlein T, Van de Waal DB, Brandenburg KM, John U, Voss M, Achterberg EP, Rost B (2016) Interactive effects of ocean acidification and nitrogen limitation on two bloom-forming dinoflagellate species. Mar Ecol Prog Ser 543:127-140. https://doi.org/10.3354/meps11568 Export citation Share:    Facebook - - linkedIn