Myora Springs is one of many groundwater discharge sites on North Stradbroke Island (Queensland, Australia). Here spring waters emerge from wetland forests to join Moreton Bay, mixing with seawater over seagrass meadows dominated by eelgrass, Zostera muelleri. We sought to determine how low pH / high CO2 conditions near the spring affect these plants and their interactions with the black rabbitfish (Siganus fuscescens), a co-occurring grazer. In paired-choice feeding trials S. fuscescens preferentially consumed Z. muelleri shoots collected nearest to Myora Springs.
Production of CO2-tolerant microalgae have received much attention as well as physicochemical fixation of CO2 in industrial flue gas. Although many microalgae that are tolerant to high levels of CO2 have been found and evaluated, the CO2 concentration for their good growth is generally lower than their maximum tolerable CO2 level. In the present study, we attempted to isolate microalgae capable of growing in high levels of CO2 (high-level-CO2-preferring microalgae, HCP-microalgae). We used a CO2-permeable polystyrene bottle for the enrichment of HCP-microalgae in environmental samples.
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.
Carbon physiology of a genetically identified Ulva rigida was investigated under different CO2(aq) and light levels. The study was designed to answer whether (1) light or exogenous inorganic carbon (Ci) pool is driving growth; and (2) elevated CO2(aq) concentration under ocean acidification (OA) will downregulate CAext-mediated inline image dehydration and alter the stable carbon isotope ($δ$13C) signatures toward more CO2 use to support higher growth rate.
The CO2-boosted trophic transfer from primary producers to herbivores has been increasingly discovered at natural CO2 vents and in laboratory experiments. Despite the emerging knowledge of this boosting effect, we do not know the extent to which it may be enhanced or dampened by ocean warming. We investigated whether ocean acidification and warming enhance the nutritional quality (C:N ratio) and energy content of turf algae, which is speculated to drive higher feeding rate, greater energy budget and eventually faster growth of herbivores.
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.
During mariculture period, maricultured macroalga Gracilaria lemaneiformis experienced seasonal temperature changes. In this study, we examine the effects of predicted ocean acidification on carbon and nitrogen accumulation and amino acids (AA) contents in G. lemaneiformis under different temperature levels. The results showed that G. lemaneiformis exhibited higher growth rates under high temperature conditions than under low temperature conditions, regardless of CO2 levels. Moreover, compared with low temperature, the culture conditions of high temperature enhanced N accumulation in G.
Ulva spp., an increasingly important food, are the dominant species of the large-scale green tides. In this study, both the growth and the physiological responses of the Ulva prolifera were studied after cultured in three different light and dark regimes (12:12, 14:10 and 16:8-h light/dark) in combination with current (420 $μ$atm; LC) and increased (1000 $μ$atm; HC) levels of atmospheric CO2. Grown rate of U.