I tend to agree - that a website should do what it's intended to do. Simplicity is busy. Members should be able to find the information or areas that they are looking for with very little difficulty.
Also a site should easy on the eyes. So the members will want to stick around to read it. Also remember the life blood of any online forum is it's people. So it needs to be warm, welcoming, and friendly.
It looks like your site is more geared towards basic information. But don't assume that everyone of your members is going to have at least a B.S. in Marine Biology. Remember K.I.S.S. - Keep It Super Simple. Instead of having all the species listed by Order names (i.e. formes), try using the common names. Such as - Carpet Sharks in place of Orectolobiformes, or Mackerel Sharks in place of Lamniformes. This may make the species a bit easier to find for the General public.