Biologists investigated the impact of ocean acidification on the shell morphology of the common limpet, Patella vulgata\textit{Patella vulgata}Patella vulgata. They sampled 450 limpets from two distinct rocky shores: one with a normal pH of 8.18.18.1 and another affected by local runoff with a lower pH of 7.87.87.8. They classified each limpet's shell morphology into two categories: 'conical' (height-to-width ratio ≥0.6\ge 0.6≥0.6) and 'flattened' (height-to-width ratio <0.6< 0.6<0.6).
They wished to test the following null hypothesis: 'There is no significant association between the pH level of the rocky shore and the frequency of limpets with conical or flattened shell morphology.'
State the name of the statistical test that the biologists should use with this categorical frequency data.
The statistical test yielded a PPP-value of 0.0080.0080.008. Explain what the biologists can conclude from this result about their null hypothesis.