The barnacle Balanus amphitrite Darwin is a dominant intertidal and major fouling organism. As its life cycle includes both sessile and pelagic phases, adaptation is a necessity to tolerate harsh conditions that are faced in the intertidal and pelagic environment. A downward trend in dissolved oxygen levels in coastal areas has been recently observed, which would have a more prominent effect on sessile organisms inhabiting the intertidal habitats. The effects of reduced dissolved oxygen levels (hypoxia) and no oxygen (anoxia) on B. amphitrite adults and nauplii was assessed. Their response was evaluated by estimating the levels of the antioxidant enzymes catalase and superoxide dismutase. The impact of desiccation on antioxidant enzymes in adult B. amphitrite collected from different tidal heights was also evaluated. When nauplii were starved, 100% mortality was observed after 64 h under hypoxia, and between 24 and 32 h under anoxia. However, when nauplii were exposed to hypoxia and anoxia along with food, their tolerance level increased. A decrease in naupliar feeding rate and oxygen consumption was observed when they were exposed to hypoxia and anoxia. A significant difference in the levels of antioxidant enzymes in adult B. amphitrite collected at different tidal levels was observed. Enzyme activity increased with increase in the duration of tidal exposure, suggesting a capability to adapt to stress in different niches. Nauplii showed antioxidant defense (increased enzyme activity) under hypoxia and anoxia. The magnitude of change in enzyme levels suggests that these enzymes could be potential biomarkers of stress.KEY WORDS: Balanus amphitrite · Desiccation · Hypoxia · Anoxia · Catalase · Superoxide dismutase 390: 157-166, 2009 In recent years a downward trend in the levels of dissolved oxygen (DO) has been observed in coastal areas worldwide (Diaz 2001). Concern over the health of estuarine habitats has prompted researchers to shift their attention to the responses of organisms to low oxygen conditions, i.e. hypoxia. The seasonal shifts in the spatial distribution of oxygen levels can result in a dramatic shift in the composition of benthic and pelagic communities and the availability of the habitat to estuarine species. Oxygen depletion occurs more frequently in coastal areas with longer water residence time, higher nutrient loads and stratified water columns (Harned & Davenport 1990, Breitburg 1992, Howell & Simpson 1994, Paerl et al. 1998, Diaz 2001. No other environmental variable of such ecological importance to estuarine and coastal marine ecosystems around the world has changed so drastically in a short period of time as DO, and this is an issue of growing global concern.
Resale or republication not permitted without written consent of the publisherMar Ecol Prog SerRelease of larvae in hypoxic or anoxic waters could have an impact on their survival and development during the planktonic phase of their life cycle. Investigations have been carried out with barnacles on their capacity to wit...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.