Ben D
28-10-2015, 10:48 AM
I have just been looking at a new paper which is extolling the virtues of green zones in Moreton Bay. It is by Olds et al. (2014) "Marine reserves help coastal ecosystems cope withextreme weather" Global Change Biology 20: 3050-3058. In it they say that coral reefs in green zones in Moreton Bay survived and recovered from the 2011 floods much better than reefs outside the green zones, and they reckon this is due to fishers taking herbivorous fish from the areas that remain fishable. The species they are talking about are blue barred parrotfish (Scarus ghobban) and surgeonfish/Australian sawtail (Prionurus microlepidotus), and they also mention happy moments (Siganus fuscescens). Populations of these were apparently higher in the green zones prior to the flood, and they are trying to say that fishing has affected the recovery of the reefs outside the green zone after the floods.
I am not convinced, as I have never heard of anyone targeting any of these species in the bay. Instead, is it possible that the green zone reefs recovered better because the better reefs were chosen as green zones in the first place, so the result could be basically due to site selection bias as they did not do surveys of herbivorous fish before/after green zone declaration ? (i.e. they may have always been higher in numbers in the green zones because the green zones had more coral in the first place - protecting the best places makes for a self fulfilling prophecy later down the track....). Does anyone have any information on whether they know any people taking these parrotfish, surgeonfish and happy moments in the bay, or not ? If so, please post up so we can see what the state of play is.
In contrast, another recent paper by Wegner et al. (2015) Effects of reduced water quality on coral reefs in and out of no-take marine reserves in Conservation Biology looked at the effects of the 2011 and 2013 floods on coral reefs in the Keppel Islands and found the reefs suffered greatly and that the green zones had either no effect or a reverse effect - with macroalgal cover higher in the no take areas. I would expect no protection from floods by MPAs , but I did not expect them to make things worse - so do these two studies just cancel each other out ? Or are the researchers in Moreton Bay actually reporting a site selection artifact because no one actually targets the fish they think are saving the corals down here ?
I am not convinced, as I have never heard of anyone targeting any of these species in the bay. Instead, is it possible that the green zone reefs recovered better because the better reefs were chosen as green zones in the first place, so the result could be basically due to site selection bias as they did not do surveys of herbivorous fish before/after green zone declaration ? (i.e. they may have always been higher in numbers in the green zones because the green zones had more coral in the first place - protecting the best places makes for a self fulfilling prophecy later down the track....). Does anyone have any information on whether they know any people taking these parrotfish, surgeonfish and happy moments in the bay, or not ? If so, please post up so we can see what the state of play is.
In contrast, another recent paper by Wegner et al. (2015) Effects of reduced water quality on coral reefs in and out of no-take marine reserves in Conservation Biology looked at the effects of the 2011 and 2013 floods on coral reefs in the Keppel Islands and found the reefs suffered greatly and that the green zones had either no effect or a reverse effect - with macroalgal cover higher in the no take areas. I would expect no protection from floods by MPAs , but I did not expect them to make things worse - so do these two studies just cancel each other out ? Or are the researchers in Moreton Bay actually reporting a site selection artifact because no one actually targets the fish they think are saving the corals down here ?