Climate Change

In this final topic, we look at further consequences of climate change. The material in this topic builds on, and to some extent integrates, issues from the previous topics in this module. It also forms the basis for Assignment 3.

1. Change in frequency and intensity of disturbance

As you have learned, one potential consequence of climate change is an increase in the intensity and/or frequency of severe storms and cyclones. Indeed, some scientists contend that the frequency or intensity of major storms has already increased; although this is disputed by others (these scientists believe that the increases are due to better technology recording more storms and estimating their intensity better).

In this section, we will look at some of the potential effects of increased disturbance, from storms, on coral reefs, through one case study: the study by Walker et al. (2009) on the "intertidal, nonscleractinian sessile fauna". Before reading the paper, it may be helpful to review some information about these animals. 

  • The "sessile fauna" are simply the animals which are either attached to, or embedded in, the bottom or each other: as a consequence, they are largely immobile.
  • The scleractinian fauna are the hard, or stony, corals; the animals people usually think of in association with coral reefs: see the Wikipedia article.
  • Thus the "nonscleractinian sessile fauna" are all the other sessile animals which live in coral reefs. These include ascidians, sponges, barnacles, sessile polychaetes and other cnidarians.
  • Areas which are exposed to the light are often occupied by either hard corals or algae, so these other animals often occur under ledges or, as in the Walker et al. (2009) study, underneath coral rubble. In fact, the assemblages of organisms studied by Walker et al. (2009) were similar to those studied by McGuinness (1987). 

With this background, read the paper: Walker, S., B. Degnan, et al. (2009). ‘Will increased storm disturbance affect the biodiversity of intertidal, nonscleractinian sessile fauna on coral reefs?’

Consider this question:
The overall conclusion from this study seems to be that increased disturbance must lead to a reduction in biodiversity in these natural communities. Can you think of any way in which this might not happen?

In the next topic, we look at the issue of rising sea level. 

References

↑ top