[Coral-List] Fast coral extension rates DO NOT equate with a healthy coral in a warming ocean

[tomascik at novuscom.net]

Hi Scott,

You may find this paper of interest.
Tom

https://www.researchgate.net/publication/259286718_Effects_of_eutrophication_on_reef_building_corals_Part_I_Growth_rates_of_reef_building_coral_Montastrea_annularis

Quoting Scott Wooldridge <swooldri23 at gmail.com>:

> Dear Fellow Coral Researchers, most particularly young scientists who are
> keen to design experiments that will advance the science behind coral reef
> biology.
>
>
> I urge you to reconsider the outdated concept that fast skeletal extension
> rates in symbiotic corals equates to a healthy and resilient coral. In
> fact, in a warming (and high pco2) ocean, I contend that it is the complete
> opposite.
>
>
> Here is a very simple experiment that can be done to test. Raise corals
> under optimal 'spring' temperature and irradiance conditions. Add variable
> concentrations of dissolved inorganic nutrients to different treatments
> such as to alter symbiont densities. You will find that under these optimal
> 'spring-type' conditions, the corals with the largest symbiont densities
> will have the fastest growth (extension) rates. Now apply these same corals
> to a warming treatment to replicate anomalous summer heat/beaching event.
> You will discover that the corals (with elevated symbiont densities) that
> have the highest growth as 'optimal' conditions, will be the first to
> bleach and die at the anomalous temperatures.
>
>
> I have previously described this phenomenon in the following manuscript in
> BioEssays:
>
>
> https://www.researchgate.net/publication/265297066_Assessing_coral_health_and_resilience_in_a_warming_ocean_Why_looks_can_be_deceptive
>
>
> which builds on a new (improved) understanding of the coral
> biomineralisation process;
>
>
> https://www.researchgate.net/publication/307732715_A_new_conceptual_model_of_coral_biomineralisation_hypoxia_as_the_physiological_driver_of_skeletal_extension
>
>
> This new conceptualisation also explains that 'high' bleaching risk areas,
> will also be the areas with the highest growth rates in non-bleaching
> years. See for example, the Great Barrier reef Porites dataset (cf fig.8)
> in paper 2.
>
>
> https://www.researchgate.net/publication/308746785_Excess_seawater_nutrients_enlarged_algal_symbiont_densities_and_bleaching_sensitive_reef_locations_1_Identifying_thresholds_of_concern_for_the_Great_Barrier_Reef_Australia
>
>
> https://www.researchgate.net/publication/308746844_Excess_seawater_nutrients_enlarged_algal_symbiont_densities_and_bleaching_sensitive_reef_locations_2_A_regional-scale_predictive_model_for_the_Great_Barrier_Reef_Australia
>
>
> Other researchers have also documented the fact that fast skeletal growth
> is indicative of areas where the health/resilience of the coral host is
> actually the most compromised. For example, Denis et al. 2013,  
> conclude, ?High
> growth rates seem to impair regeneration capacity. We show that
> environmental conditions conducive to high zooxanthellae densities in
> corals are related to fast skeletal growth but also to reduced lesion
> regeneration rates ?
>
>
> Denis V, Guillaume MMM, Goutx M, de Palmas S, Debreuil J, Baker AC, et al.
> (2013) Fast Growth May Impair Regeneration Capacity in the Branching
> Coral *Acropora
> muricata*. PLoS ONE 8(8): e72618.
> https://doi.org/10.1371/journal.pone.0072618
>
>
>
>
> In conclusion, I contend, perhaps more contentiously, that all of these
> findings lead to the obvious conclusion that symbiotic corals are ?the
> living dead? in the modern ?Anthropocene? ocean.
>
>
> https://www.researchgate.net/publication/317100418_Instability_and_breakdown_of_the_coral-algae_symbiosis_upon_exceedence_of_the_interglacial_pCO2_threshold_260_ppmv_the_%27%27missing%27%27_Earth-System_feedback_mechanism
>
>
>
> That is, unless they have plasticity for heterotrophic feeding during
> periods of autotrophic stress.
>
>
> https://www.researchgate.net/publication/269991541_2_3_Formalising_a_mechanistic_linkage_between_heterotrophic_feeding_and_thermal_bleaching_resistance
>
>
>
> My hope, is that these ideas will challenge us to move forward with some
> new thinking.
>
>
> Scott
>
>
> https://www.researchgate.net/profile/Scott_Wooldridge
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