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3.4 Harmful algal blooms

Some CDR methods also have risks. One is rapid escape of stored CO2 into the atmosphere, reducing its effectiveness.

Iron fertilisation may harm marine ecosystems: for example, by creating ‘red tides’ of harmful algae (Figure 7). Such a red tide in 2013 was reported to have killed 276 manatees in Florida (Brown, 2013). Red tides also pose a risk to human health through eating contaminated shellfish.

This is a photograph of a 'red tide' in the ocean. It appears as a bright red fringe on the ocean very near the coastline.
Figure 7 A ‘red tide’ – the common name for a harmful algal bloom of toxic types of phytoplankton – this one is near Cape Rodney, New Zealand.

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