Nutrients

Davies et al. (2008) noted a significant influence of nutrients (phosphate, nitrate and silicate) on Lophelia pertusa distribution. Nutrients can have a negative impact on shallow water coral reefs (McCook, 1999). Coral calcification increases with phosphorus supplementation, though skeletal density decreases making the coral vulnerable to breakage, further more a reduction of fertilization success is also observed (Koop et al., 2001; Harrison and Ward, 2001). Increased nitrate concentrations led to reduced calcification rates, stunted coral growth, reduced settlement of coral larvae and changes to physical appearance (Marubini and Davies, 1996; Marubini and Thake, 1999; Koop et al., 2001; Schlöder and D’Croz, 2004). Furthermore high nitrate and phosphate concentrations together significantly reduced the growth rate of Acropora cervicornis (Renegar and Riegl, 2005). Although these results are from shallow-water corals, it is likely that similar responses would be seen in cold-water corals. A negative correlation between cold-water corals species richness and silicate concentrations was observed by Bonilla and Pinon (2002). Low silicate levels may indicate low primary production suggesting a limited food supply.

Davies et al. (2008) however acknowledges that an intermediate concentration is required, or at least tolerated (table 1). More research is need about the effects of nutrients on cold-water corals, but they appear to be significant drivers when predicting habitat suitability.

Table 1. Mean minimum and maximum levels of nutrients from 1675 locations where Lophelia pertusa was present globally. Adapted from Davies et al. (2008).

NutrientMeanMinimumMaximum
Nitrate (μM)14.2141.8
Phosphate (μM)10.063.3
Silicate (μM) 10.91182.8

 

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