Changes in pH at the exterior surface of plankton with ocean acidification

Anthropogenically released CO2 is dissolving in the ocean, causing a decrease in bulk-seawater pH (ocean acidification). Projections indicate that the pH will drop 0.3 units from its present value by 2100 (ref. 1). However, it is unclear how the growth of plankton is likely to respond. Using simulations we demonstrate how pH and carbonate chemistry at the exterior surface of marine organisms deviates increasingly from those of the bulk sea water as organism metabolic activity and size increases. These deviations will increase in the future as the buffering capacity of sea water decreases with decreased pH and as metabolic activity increases with raised seawater temperatures. We show that many marine plankton will experience pH conditions completely outside their recent historical range. However, ocean acidification is likely to have differing impacts on plankton physiology as taxon-specific differences in organism size, metabolic activity and growth rates during blooms result in very different microenvironments around the organism. This is an important consideration for future studies in ocean acidification as the carbonate chemistry experienced by most planktonic organisms will probably be considerably different from that measured in bulk-seawater samples. An understanding of these deviations will assist interpretation of the impacts of ocean acidification on plankton of different size and metabolic activity.

Social impacts of a temperate fisheries closure: understanding stakeholders' views

The social dimensions of marine protected areas (MPAs) play an important role in MPA success, yet these social dimensions are little understood. We explore the social impacts arising from the establishment of an MPA using Lyme Bay (south west England) as a case study. Through a series of small group semi-structured interviews the social impacts experienced by fishermen (mobile and static gear), recreational users (divers and sea anglers) and recreation service providers (charter boat and dive businesses) were explored. The social impacts expressed varied according to activity in which the stakeholder group engaged. Negative themes included lengthening fishing trips, tension and conflict, fishermen identity, equity and uncertainty in the long-term. Positive themes included improved experiences for both commercial fishermen and recreational users, and expectations for long-term benefits. These impacts need to be understood because they influence stakeholder behaviour. Failure to interpret stakeholder responses may lead to poor decision-making and worsening stakeholder relations. These findings have implications for the success of the MPA in Lyme Bay, but also for the future network of marine conservation zones around the UK. Any assessment of MPA impacts must therefore identify social as well as economic and environmental change.