Can marine reserves promote recovery from coral bleaching?

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In relation to the Nature paper "Predicting climate-driven regime shifts versus rebound potential in coral reefs"

The finding from this paper that “Reefs within no-take marine reserves were no more likely to recover than reefs in fished areas” could be related to tendency for marine reserves in Seychelles to be designated in shallower areas that are under pressure from fishing, nutrient loading, etc, rather than in deeper, more remote residual areas with lower water temperatures that are not under pressure? The real worry with this paper is that readers will go away with the take-home message that marine reserves do not promote resilience/recovery, when this finding is more an artifact of the criteria for siting marine reserve designations in the Seychelles? If it is accepted that structural complexity, density of juvenile corals and herbivorous fishes, and low nutrient loads are attributes that promote resilience/recovery, surely marine reserves have the potential to promote such attributes and thereby recovery from coral bleaching. The lack of impact of marine reserves in this study could be more to do with location of marine reserves in more used areas and their lack of effectiveness in reducing impacts of such uses, rather than marine reserves not having the potential to promote resilience/recovery, but my worry is that such caveats will not be considered in the message that people may hear, especially when findings are transferred from the Seychelles to the Great Barrier Reef...

Comments

I agree - this article raises a lot of questions. Seychelles' no-take reserves are very poorly enforced for a number of reasons. The national park authority is chronically short of staff and resources, as recent government reforms involved a drastic reduction in funding and consequently priority is afforded to revenue collection via tourist entry fees rather than expenditure on basic monitoring. There is limited public awareness or willingness to observe fishing restrictions, whilst recent increases in fuel prices and limited availability of ice and cold storage places greater pressure on nearshore fisheries where most MPAs are sited. To equate no-take reserves with unregulated areas implies that enforcement is the difference between the two - which is clearly not the case in Seychelles.

I think it is really important to keep in mind the purposes of reserves.   On the GBR, the intent is to enhance the resilience of the overall system, not just the reserve zones, and to do that principally by regulating fishing pressure; a wide range of other measures are in place to address other contributing factors for resilience. Albeit not sufficient to be effective.

Two points then emerge:

1.Some aspects or resilience factors we might expect to measure differences at the scale of in & out of reserves –e.g. stocks of fish that are relatively sedentary. But many aspect we would expect to emerge at the scale of the entire GBR, and that is a good thing- we aim to protect the entire GBR. But it is a scientific challenge to demonstrate – we don’t have replicate, controlled GBRs.

2.No single measure can reasonably be expected to provide protection against all threats at all scales (hence the need for a portfolio approach), but in particular, the magnitude of threats, especially bleaching, currently hitting the GBR is simply enormous, and would outweigh the benefits of many otherwise appropriate management strategies. Seatbelts and airbags are extremely good ideas, but they won’t provide enough protection in a really major car crash.

3. Ultimately, bleaching is caused by ocean warming, in turn a result of carbon emissions. We need to reduce global carbon emissions. MPAs and other measures are valuable complements to that, but don't obviate the need.

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