Diurnal and seasonal variation of particle and dissolved organic matter release by the coral Acropora tenuis

Release rates of particulate organic carbon and nitrogen (POC and PON) and dissolved organic carbon (DOC) from the scleractinian coral Acropora tenuis were measured during the day and night in summer and winter seasons. Physiological parameters including calcification, photosynthesis and respiration rates were also measured simultaneously. The release rate of both POC and DOC was significantly higher in summer compared to winter and higher during the day compared to the night. The daily release rate of total organic carbon (POC + DOC) was 1,094 and 219 μmol C cm−2 d−1 for summer and winter, respectively, being 4.9 times higher in summer. The POC:PON ratios of the particulate organic matter released during daytime in both seasons (summer: 12.8 ± 5.7, winter: 12.0 ± 4.1) were significantly higher than those during nighttime (summer: 6.1 ± 2.5, winter: 2.2 ± 1.8). The DOC:POC ratio was 0.5 ± 0.03 during summer and 0.32 ± 0.98 during winter, suggesting higher mucus release in particulate form. Daily net production was estimated to be 199 and 158 μg C cm−2d−1 for summer and winter, respectively, with the amount of carbon released as mucus accounting for 6.5% and 1.6% of the net carbon fixation, respectively. The study reveals diurnal and seasonal changes in the quantity and quality of mucus released from this coral species. Since coral mucus is used as a food source by reef macro-organisms, and can also serve as an energy source for micro-organisms, the observed changes in mucus release rates are expected to influence the seasonal dynamics of organic carbon and nitrogen cycling over coral reefs

Effects of high CO2 seawater on the copepod (Acartia tsuensis) through all life stages and subsequent generations

We studied the effects of exposure to seawater equilibrated with CO2-enriched air (CO2 2380 ppm) from eggs to maturity and over two subsequent generations on the copepod Acartia tsuensis. Compared to the control (CO2 380 ppm), high CO2 exposure through all life stages of the 1st generation copepods did not significantly affect survival, body size or developmental speed. Egg production and hatching rates were also not significantly different between the initial generation of females exposed to high CO2 and the 1st and 2nd generation females developed from eggs to maturity in high CO2. Thus, the copepods appear more tolerant to increased CO2 than other marine organisms previously investigated for CO2 tolerance (i.e., sea urchins and bivalves). However, the crucial importance of copepods in marine ecosystems requires thorough evaluation of the overall impacts of marine environmental changes predicted to occur with increased CO2 concentrations, i.e., increased temperature, enhanced UV irradiation, and changes in the community structure and nutritional value of phytoplankton

Impacts of ocean acidification on the ecophysiology of pteropod Limacina helicina

第3回極域科学シンポジウム　横断セッション「南極海季節的海氷域における生物地球化学」11月26日（月） 国立極地研究所 ３階ラウン

Responses of Antarctic marine ecosystems to global environmental changes with carbonate systems (RAMEEC) – Preliminary report of JARE53 -

第3回極域科学シンポジウム　横断セッション「南極海季節的海氷域における生物地球化学」11月26日（月） 統計数理研究所 セミナー

Impact estimation of Southern Ocean acidification on calcium carbonate phytoplankton (haptophytes)

第3回極域科学シンポジウム　横断セッション「南極海季節的海氷域における生物地球化学」11月26日（月） 統計数理研究所 セミナー

ニサンカ タンソ ノウド ノ ジョウショウ ガ カイヨウ セイブツ ニ アタエル エイキョウ

京都大学0048新制・課程博士博士(理学)甲第10647号理博第2789号新制||理||1410(附属図書館)UT51-2004-G494京都大学大学院理学研究科生物科学専攻(主査)教授 白山 義久, 教授 堀 道雄, 教授 今福 道夫学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDA

Effects of CO2-driven ocean acidification on the early developmental stages of invertebrates

CO2 emissions arising from the burning of fossil fuels have altered seawater chemistry far more rapidly than the Earth has previously experienced, and the rate and extent of this change are expected to affect shallow water marine organisms. The increased CO2 diffuses from the atmosphere into ocean surface waters, resulting in increased partial pressure of CO2, and reduced [CO32-] and pH. The CO 2-driven ocean acidification leads to a decrease in calcium carbonate (CaCO3) saturation state in the ocean surface waters and has potential impacts on calcifiers. The present study focuses on the effects of ocean acidification on early developmental and reproductive stages of calcifiers, both of which are believed to be the most vulnerable stages to environmental change within a life cycle. Laboratory experiments revealed that ocean acidification has negative impacts on the fertilization, cleavage, larva, settlement and reproductive stages of several marine calcifiers, including echinoderm, bivalve, coral and crustacean species. There appear to be significant ontogenetic impacts and species-specific differences in tolerance to the high CO2 levels. The conclusion is that future changes in ocean acidity will potentially impact the population size and dynamics, as well as the community structure of calcifiers, and will therefore have negative impacts on marine ecosystems. Further studies are needed to evaluate the potential impacts on non-calcifiers, as well as the synergistic impacts of ocean acidification and climate change. Studies should also focus on the adaptive capability of marine organisms, which will be crucial to the ability to forecast how marine organisms and ecosystems will respond to the world\u27s oceans as they warm and acidify

Seawater carbonate chemistry and processes during experiments with seaurchins Hemicentrotus pulcherrimus and Echinometra mathaei, 2004

Increased carbon dioxide (CO2) concentration in the atmosphere will change the balance of the components of carbonate chemistry and reduce the pH at the ocean surface. Here, we report the effects of increased CO2 concentration on the early development of the sea urchins Hemicentrotus pulcherrimus and Echinometra mathaei. We examined the fertilization, early cleavage, and pluteus larval stage to evaluate the impact of elevated CO2 concentration on fertilization rate, cleavage rate, developmental speed, and pluteus larval morphology. Furthermore, we compared the effects of CO2 and HCl at the same pH in an attempt to elucidate any differences between the two. We found that fertilization rate, cleavage rate, developmental speed, and pluteus larval size all tended to decrease with increasing CO2 concentration. Furthermore, CO2-seawater had a more severe effect than HCl-seawater on the fertilization rate. By contrast, the effects on cleavage rate, developmental speed, and pluteus larval morphology were similar for CO2- and HCl-seawater. Our results suggest that both decreased pH and altered carbonate chemistry affect the early development and life history of marine animals, implying that increased seawater CO2 concentration will seriously alter marine ecosystems. The effects of CO2 itself on marine organisms therefore requires further clarification