Modern seawater acidification: the response of foraminifera to high-CO2 conditions in the Mediterranean Sea

The seas around the island of Ischia (Italy) have a lowered pH as a result of volcanic gas vents that emit carbon dioxide from the sea floor at ambient seawater temperatures. These areas of acidified seawater provide natural laboratories in which to study the long-term biological response to rising CO₂ levels. Benthic foraminifera (single-celled protists) are particularly interesting as they have short life histories, are environmentally sensitive and have an excellent fossil record. Here, we examine changes in foraminiferal assemblages along pH gradients at CO₂ vents on the coast of Ischia and show that the foraminiferal distribution, diversity and nature of the fauna change markedly in the living assemblages as pH decreases.

Coccolithophores lipid and carbon isotope composition and their variability related to changes in seawater carbonate chemistry

Growth rate, C:N ratio, phospholipid-derived fatty acids (PLFA) distribution and organic carbon isotope composition (∂¹³C) of both life stages of the Prymnesiophyceae Emiliania huxleyi (Lohmann), Calcidiscus leptoporus (Murray and Blackman) and Syracosphaera pulchra (Lohman) were analyzed. Cultures were grown at two different CO₂ partial pressures (pCO₂, 400 and 760 μatm) under nutrient-replete conditions. Growth rates (μ) increased at 760 μatm in all species. C:N ratios were unaffected by pCO₂ in C. leptoporus and in the diploid stage of E. huxleyi; they significantly decreased in the haploid stage of E. huxleyi and in both life stages of S. pulchra. At 400 μatm, high similarity was found between the lipid composition of C. leptoporus and S. pulchra differing from that of E. huxleyi. The haploid and diploid life stages showed significant differences in mono- and polyunsaturated C18 fatty acids (MUFA and PUFA), which were more abundant in either stage depending on the species. Except for palmitoleic, vaccenic acids and docosahexaeonic acid (DHA), C. leptoporus and S. pulchra fatty acids were lower compared to those of E. huxleyi. Differences in ∂¹³C between particulate organic carbon (POC) and PLFA (∆∂¹³C_lipid-POC) showed common trends at both pCO₂: palmitoleic, oleic acids and DHA were systematically depleted compared to total cell biomass, C18 PUFA were enriched while saturated fatty acids (SAFA) were enriched in C. leptoporus and S. pulchra and depleted in E. huxleyi. Elevated pCO₂ influenced PLFA abundance, ∂¹³C of lipids and POC in a highly species-specific way. Fatty acids were generally more depleted at 760 μatm than at 400 μatm but the effect was variable among PLFA classes. The relationship between coccolithophore isotopic and PLFA composition and CO₂ concentration are analyzed and consequent variations in the future web-chain related to changes in carbonate chemistry are discussed.

Ocean Acidification: An evening with seminar with scientific experts (Port Townsend)

Title of Event: Ocean Acidification: An evening with seminar with scientific experts.

Host/Organization: Northwest Straits Comission, Port Townsend Marine Science Center, Olympic Coast Marine Sanctuary, Sustainable Fisheries Partnership, WSU Beachwatchers

Event Date and Time: Oct. 7, 2010 –  6:00 pm

Address: Northwest Maritime Center,  431 Water St., Port Townsend, WA 98368

Description: The purpose of the seminar is to share the current state of knowledge regarding ocean acidification, and provide an overview of scientific research being conducted in this region. This event is free and open to the public.

Un monde trop acide pour les récifs coralliens (in French)

On les savait menaces par l’augmentation de température des eaux de surface. Mais aujourd’hui les coraux sont aussi confrontés a l’acidification des océans. Ont-ils une chance de survivre?

Announcement of opportunity for studentship proposals

Closing date: 16:00 on 26 October 2010

Proposals are invited for studentships as part of the UK Ocean Acidification Research Programme. This £12m collaborative programme is a Living With Environmental Change (LWEC) accredited programme and is co-funded by NERC, the Department for Environment, Food & Rural Affairs (Defra) and the Department of Energy & Climate Change (DECC).

This integrated strategic programme directly relates to the delivery of the NERC strategy (Earth system science and biodiversity science themes) and the UK government’s strategic objectives with respect to adapting to, and mitigating, climate change and ensuring a healthy resilient, productive and diverse natural environment.

The aim of this call is to fund up to three studentships that will address Science Deliverable 5 of the programme:

“Provision of evidence from the palaeo record of past changes in ocean acidity and resultant changes in marine species’ composition and Earth system function.”