Ocean acidification and warming are predicted to affect the ability of marine bivalves to build their shells, but little is known about the underlying mechanisms. Shell formation is an extremely complex process requiring a detailed understanding of biomineralization processes. Sodium incorporation into the shells would increase if bivalves rely on the exchange of Na+/H+ to maintain homeostasis for shell formation, thereby shedding new light on the acid-base and ionic regulation at the calcifying front.
While ocean acidification (OA) is expected to have wide-ranging negative effects on marine species, organisms currently living in variable pH environments that expose them intermittently to pH values approaching those predicted for the future, may be better adapted to tolerate prolonged exposure to high pCO 2 levels caused by OA. Seasonal upwelling brings low pH water to the surface along the Pacific Coast of North America.
Anthropogenic carbon dioxide (CO2) emissions simultaneously increase ocean temperatures and reduce ocean surface pH, a process termed ocean acidification (OA). OA is expected to negatively affect the growth and physiology of many calcified organisms, but the response of non-calcified (fleshy) organisms is less well understood. Rising temperatures and pCO2 can enhance photosynthetic rates (within tolerance limits). Therefore, warming may interact with OA to alter biological responses of macroalgae in complicated ways.
Ulva is the dominant genus in the green tide events and is considered to have efficient CO2 concentrating mechanisms (CCMs). However, little is understood regarding the impacts of ocean acidification on the CCMs of Ulva and the consequences of thalli's acclimation to ocean acidification in terms of responding to environmental factors. Here, we grew a cosmopolitan green alga, Ulva linza at ambient (LC) and elevated (HC) CO2 levels and investigated the alteration of CCMs in U. linza grown at HC and its responses to the changed seawater carbon chemistry and light intensity.
Hizikia fusiforme (Harv.) Okamura (brown seaweed) was cultured using aeration with two CO2 conditions: outdoor air (actual atmospheric CO2 concentration, averaging 360 $μ$l l-1) and CO2-enriched air (averaging 700 $μ$l l-1), to investigate the possible adjustments of elevated atmospheric CO2 to the growth, photosynthesis and nitrogen metabolism in this mariculture species. Aeration with CO2-enriched air reduced the pH in the culture medium in comparison with aeration with air. The mean relative growth rate was enhanced when H. fusiforme was grown at high CO2 with respect to normal CO2.
Multiple aspects of climate change are expected to co-occur such that ocean acidification will take place in conjunction with warming and a range of trophic changes. Previous studies have demonstrated that nutritional condition plays a significant role in the responses of invertebrates to ocean acidification, but similar studies have yet to be conducted with marine fishes. In this study, we examined the potential interactive effects of elevated CO2 levels and nutritional stress on the growth and development of northern rock sole (Lepidopsetta polyxystra).
We tested the hypothesis that ocean acidification (OA) affects spatial competition among scleractinian corals. Competitive ability was evaluated indirectly by linear extension of Porites lutea and Montipora aequituberculata placed in intraspecific, interspecific, and control pairings (paired with dead coral skeleton) and exposed to ambient (̃400 µatm) and elevated (\̃1000 µatm) pCO2 in experiments conducted in Moorea, French Polynesia, and Okinawa, Japan. High pCO2 had no effect on linear extension of M.