Summary: Habitat-level and other non-species indicators may be more practically useful than evidence of extinctions.

This is very interesting. I think Dr Boero correctly identifies the problem, but I'm not sure focus on the taxonomic literature will provide much of a solution, not least because most knowledge about marine life is relatively recent. The fact that we can't point to specific extinctions presumably reflects lack of knowledge, not lack of extinctions? I think the "biodiversity has increased" argument should not directly cause too many communication problems: it is easy to explain that we're only now starting to find out everything that's there, and we still don't know what we've lost or are losing, and that biodiversity has not increased, we've just got better at finding it. However the argument that we don't know enough can itself be a problem ("go away and come back when you do know") - focusing at scales at which we do have reasonable knowledge (for example, status of habitats) may be a partial solution.

From the public communication perspective, I'm not surprised to hear that "Tricyclusa singularis is extinct" doesn't grab public attention. I suspect if you asked people to pick what it was (or had been):
(a) a dinosaur
(b) a 70s rock band
(c) a tropical disease
(d) an invisible sea creature
the answers might be pretty random (I'm not even going to start with Fucus virsoides). Why should anyone care?

Extinctions may be especially hard to prove in marine environments, we know relatively little about the implications, and the public knows a great deal less. Dr Boero suggests that it might be better to focus at the habitat level (I agree) but suggests that this is less impacting (I disagree), and that there are no extinct habitats (I don't think that matters). I think it is indeed more productive to move away from a species focus to look at features other than extinctions, especially where people can see that there is a clear implication for humans, or a clear feeling that "something's not right", and I think these can have high levels of impact. For example:

- levels of ecosystem service (collapsed fish stocks, recruitment failures etc.)
- genetic effects (reduced size at sexual maturity due to selective harvesting; gender balance/switching age in sequential hermaphrodites - I think people would react more strongly to clear evidence of this sort of human interference than to possible extinctions of unknown things)
- populations of charismatic predators (sea birds, seals etc.)
- habitat destruction (scallop-dredged sea grass beds, bleached coral etc. - before/after photographic evidence of this can be very powerful for communicating, and indicators are relatively easy to derive compared with species-level assessments)
- (suspected) extirpations: even where extinction can't be demonstrated, extirpations might be; commercial extinctions can be easier still to establish. This might be enough for communication / policy purposes - e.g. there's a pretty clear message in saying the Irish Sea Skate is no longer to be found in the Irish Sea (I don't know if that's true or not, it could be a filthy rumour put about by elasmobranch-haters; it's just here to illustrate the point).

I don't believe these messages are unique to the marine environment, either. Similar points could apply to soil biodiversity in particular. But more generally images of damaged forest habitat, or measurements of reduced (value of) pollinator services, are probably more salient for both public and management than news that the lesser-spotted stamen-twitching beetle has (we think, but we're not sure) vanished from its range. Generally, I think our concept of species may not provide the most relevant measures of biodiversity from a communications or practical management perspective, except when we're dealing with large, charismatic animals (tigers, pandas, spotted owls, whales) or species we exploit directly. Beyond that, a service-level approach may be more useful (pollinators, bioturbators etc.)

The challenge is to make the science link diversity to service and on to communication indicators and management options. We might feel that species protection should be of primary importance, but in practice, demonstrating the importance of biodiversity to services, and showing what to do about it, is how we can win the policy battle.

Dr Rob Tinch
Director
Environmental Futures Ltd.