Bleaching in larger benthic foraminifera from the Great Barrier Reef

Brief description

Experiments were conducted to determine whether larger benthic foraminifera is prone to bleaching caused by increases in temperature and nutrient levels. The experiments aimed to characterise the physiological stress threatening these species, predicted to occur on tropical reef waters in the near future. Nutrient levels were chosen to represent naturally occurring nutrient concentrations during flood-plume events on the GBR, and temperatures were chosen to reflect current and future predictions for the GBR (Lough et al. 2006; Lough 2007). Specimens of Amphistegina radiata and Heterostegina depressa were collected during dry season 2009 and wet season 2010, from the Whitsundays area nearby sites Double Cone Island, Border Island, Deloraine Island and Edward Island. Calcarina hispida specimens were collected from Heron Island 2009 and Calcarina mayorii from Magnetic Island. Daily average SST was obtained from AIMS AWS stations at Hardy Reef and Heron Island, temperature logger are Nelly Bay. Additional samplesof A. radiata and H. depressa were collected from Dent Island and Bait Reef. A 6 day experiment with temperature manipulation were carried out with five individually set temperatures 23, 28, 30 32 and 33, exposing samples of A.radiata, H. depressa, and C. hispida. These experiments were repeated three times for A. radiata and H. depressa. To avoid thermal shock, the specimens were gradually introduced to the five different temperature treatments. Subsequent experiments used light levels of 11 -15 µmol photos m-2 s-1. A 30-day flow-through experiment was conducted where the effects of three temperature ranges and three nutrient levels were studied simultaneously: Temperature: 26, 29 and 31, and nutrient concentrations of 0.5, 1.0 and 1.4 µmol L-1. Specimens of A.radiata and H.depressa contained in six-well plates, and C. mayorii was contained in polypropylene tubes. Analysis included photosynthetic efficiency, Chl a, motility and growth measurements in A. raditata. Results of these experiments suggested that physiological stress and bleaching are species specific. This research was supported by the Australian government’s Marine and Tropical Sciences Research Facility, implemented by the Reef and Rainforest Research Centre in northern Queensland, Australia.

Lineage

Maintenance and Update Frequency: notPlanned

Notes

Credit
Uthicke, Sven, Dr. Australian Institute of Marine Science (AIMS)