Nitrogen Perturbations to Reefs

Coral reefs are not stable, static communities living in benign environments, but rather are very dynamic ecosystems which are subject to frequent natural physical disturbance on times scales which vary from minutes to years (Furnas, 2003 Furnas 

Whether reefs will have the residence to recover from multiple anthropogenic stresses (Hughes and Connell, 1999) is a major issue of concern to scientists and resource managers. Recent studies have highhghted the serious decHne in water quahty in coastal environments, including coral reef areas (Fabricius, 2005 Hutchins et al, 2005 Kuntz et al, 2005 Wilkinson, 2002 Barile, 2004). 

Elevated nutrients (ammonium, nitrate and phosphate) may derive from multiple sources (see above) and can directly affect both adult coral colonies as well as reproduction and recruitment of larvae in a number of ways (Fabricius, 2005). 

Terrestrial runoff is a major concern for areas with coral reefs. Nutrient enrichment, sedimentation, and turbidity can all degrade reefs at local scales (Fabricius, 2005). While there are some coastal coral reefs that can flourish in relatively high nutrient and high levels of particulate matter, they tend to be restricted in depth to 10 m whereas in clearer offshore reefal systems they may extend to 40 m (Fabricius, 2005). Some corals can use the particulate matter for nutrition. However, there is a fine line, between increased nutrient availabdity for the coral for ingestion and the tipping point at which the corals are unable to cope with sedimentation and silting affects. (Anthony, 2000 Anthony and Fabricius, 2000 Fabricius and Wolanski, 2000 Mills and Sebens, 2004 Mills et ah, 2004). 

Other anthropogenic, terrestrial sources of nitrogen to reefs include groundwater (D Elia et ah, 1981 Littler et ah, 2006), and sewage (Hanson and Gundersen, 1976 Lapointe et ah, 2005a,b Risk and Erdmann, 2000 Szmant Froelich, 2002). Since 

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