| Summary: | Natural volcanic vents on the sea floor around the island of Ischia emit CO2 at ambient seawater temperatures, producing a similar acidification effect to that predicted for the future. These areas of acidified seawater provide a unique opportunity to study the ecosystem effects of ocean acidification. Benthic foraminifera provide powerful tools in assessing many environmental and ecological impacts, due to their short life cycles, widespread habitat colonisation, environmental sensitivity and excellent fossil record. Here, the response of foraminiferal assemblages are studied along pH gradients at CO2 vents in the shallow seas around the island Ischia, which demonstrate marked changes in foraminiferal abundance, diversity and assemblage composition as pH decreases. In 1992, after a period of heavy rainfall, Wheal Jane tin mine flooded, releasing 50 million litres of acidic, heavy metal contaminated mine waste into the Carnon River and subsequently Restronguet Creek. From October 1992 to October 1996, a monitoring programme was inaugurated to document the effects on the foraminiferal fauna, geochemistry of the surficial sediments and chemistry of the water entering Restronguet Creek. In 2004 this foraminiferal monitoring programme was resumed and showed an increase in foraminiferal abundance but noted a conspicuous lack of typical estuarine agglutinated taxa, such as Jadammina macrescens, Miliammina fusca and Trochammina inflata. In July 2010, upper mudflat sediments in Restronguet Creek were sampled in order to address the absence of typical agglutinating foraminifera. Atypical assemblages characterise Restronguet Creek, with only three indigenous taxa, Haynesina germanica, Elphidium williamsoni and Ammonia aberdoveyensis, all of which are calcareous. However, a very small proportion of unstained (= dead) agglutinating forms were documented at the north side of Restronguet Creek, a result itherto undetected. h Faculty of Science
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