RESUMEN
CaCO3 -saturated saline waters at pH values below 8.5 are characterized by two stationary equilibrium states: reversible chemical calcification/decalcification associated with acid dissociation, Ca(2+) +HCO3 (-) âCaCO3 +H(+) ; and reversible static physical precipitation/dissolution, Ca(2+) +CO3 (2-) âCaCO3 . The former reversible reaction was determined using a strong base and acid titration. The saturation state described by the pH/PCO2 -independent solubility product, [Ca(2+) ][CO3 (2-) ], may not be observed at pH below 8.5 because [Ca(2+) ][CO3 (2-) ]/([Ca(2+) ][HCO3 (-) ]) âª1. Since proton transfer dynamics controls all reversible acid dissociation reactions in saline waters, the concentrations of calcium ion and dissolved inorganic carbon (DIC) were expressed as a function of dual variables, pH and PCO2 . The negative impact of ocean acidification on marine calcifying organisms was confirmed by applying the experimental culture data of each PCO2 /pH-dependent coral polyp skeleton weight (Wskel) to the proton transfer idea. The skeleton formation of each coral polyp was performed in microspaces beneath its aboral ectoderm. This resulted in a decalcification of 14 weight %, a normalized CaCO3 saturation state Λ of 1.3 at PCO2 ≈400â ppm and pH ≈8.0, and serious decalcification of 45 % and Λ 2.5 at PCO2 ≈1000â ppm and pH ≈7.8.
Asunto(s)
Antozoos/anatomía & histología , Antozoos/fisiología , Calcificación Fisiológica , Carbonato de Calcio/metabolismo , Ácidos/química , Animales , Carbonato de Calcio/química , Concentración de Iones de Hidrógeno , Protones , Salinidad , SolubilidadRESUMEN
In this study, the effects of silver nanocolloids (SNCs) on the early life stages of the reef-building coral Acropora japonica were investigated. The tolerance of this species to SNC contamination was estimated by exposing gametes, larvae, and primary polyps to a range of SNC concentrations (0, 0.5, 5, 50, and 500 µg l(-1)). Pure SNCs were immediately ionized to Ag(+) in seawater and concentrations of ≥50 µg l(-1) SNC had a significant detrimental effect on fertilization, larval metamorphosis, and primary polyp growth. Exposure to 50 µg l(-1) SNC did not significantly affect larval survival; however, the larvae were deformed and lost their ability to metamorphose. At the highest concentration (500 µg l(-1) SNC), all gametes, larvae, and primary polyps died. These experiments provide the first data on the effects of silver-nanomaterial-contaminated seawater on cnidarians, and suggest that silver nanomaterials can influence the early development of corals through anthropogenic wastewater inputs.
Asunto(s)
Antozoos/efectos de los fármacos , Antozoos/crecimiento & desarrollo , Nanopartículas del Metal/toxicidad , Plata/toxicidad , Análisis de Varianza , Animales , Relación Dosis-Respuesta a Droga , Fertilización/efectos de los fármacos , Células Germinativas/efectos de los fármacos , Japón , Larva/efectos de los fármacos , Metamorfosis Biológica/efectos de los fármacosRESUMEN
Ocean acidification is now recognized as a threat to marine ecosystems; however, the effect of ocean acidification on fertilization in marine organisms is still largely unknown. In this study, we focused on sperm flagellar motility in broadcast spawning reef invertebrates (a coral and a sea cucumber). Below pH 7.7, the pH predicted to occur within the next 100 years, sperm flagellar motility was seriously impaired in these organisms. Considering that sperm flagellar motility is indispensable for transporting the paternal haploid genome for fertilization, fertilization taking place in seawater may decline in the not too distant future. Urgent surveys are necessary for a better understanding of the physiological consequences of ocean acidification on sperm flagellar motility in a wide range of marine invertebrates.