Effects of sedimentation and the herbicide diuron on crustose coralline algae (CCA)

Full description

Experiments were conducted to determine the effects of sedimentation and the herbicide diuron on crustose coralline algae (CCA). Three species of CCA were subjected to exposure to sediments and one species to sediments and diuron individually and in combination. This research aimed to observe altered photophysiology, bleaching and survival.


Three species of CCA were collected from midshelf reefs along the Innisfail coastline, H. reinboldii, Neogoniolithon fosliei and Porolithon onkodes. P. Onokodes was also collected from Davies reef for the combined sediment and diuron experiments.


Variations in sediment type included estuarine sediment collected from the Herbert River and offshore sediment Otter Reef:



    fine estuarine particle <63μm

    medium-fine estuarine particle size 63-250μm

    fine offshore sediment <63μm

    fine calcareous <63μm derived from sawdust from cutting massive Porites corals



Diuron was prepared in a stock solution prior to experimentation, in addition to a carrier control treatment. Aquaria were positioned under 70% shading outdoors, with a maintained temperature of 28°C.


Pulse amplitude modulated (PAM) fluorometry measured the photosynthetic efficiency of the CCA species following short term exposure of the CCA fragments to the four sediment types. Constant fluorescence and maximum fluorescence were determined, as well as effective photosystem II quantum yields of light adapted CCA. Fragments were then placed in sediment-free aquaria for recovery.


Combined diuron and sediment exposure experiments were also conducted to determine whether sedimentation stress is altered by the presence of herbicide. One type of sediment was used (fine estuarine sediment) and four diuron concentrations of nominally 1, 3, 10, 30 μg L−1. Diuron stock concentrations were added to sediments 24hrs prior to CCA exposure, and then added to the experimental aquaria for up to 105 hours. At the pre-nominated exposure times, fragments were removed from the aquaria and responses of photosynthetic yields were measured.

Lineage

Maintenance and Update Frequency: notPlanned

Statement: Negri AP, Vollhardt C, Humphrey CA, Heyward AJ, Jones RJ, Eaglesham G and Fabricius KE (2005) Effects of the herbicide diuron on the early life history stages of coral. Marine Pollution Bulletin. 51: 370-383. U. Schreiber, U. Schliwa, W. Bilger (1986) Continuos recording of photochemical and non-photochemical chlorophyll fluorescence quenching with a new type of modulation fluorometry. Photosynthesis, 10, pp. 51-62

Notes

Credit
Fabricius, K. Australian Institute of Marine Science (AIMS)