[Coral-List] Szmant 2002: Great review on nutrient enrichment on coral reefs

John Ogden jogden at usf.edu
Wed May 2 14:40:25 EDT 2018


Thanks John and Dennis.  it is good to see this again.  This paper was a 
critical contribution to the "nutrient wars" fought largely in the press 
in the first years of the Keys Sanctuary.   John

On 5/2/2018 10:27 AM, Dennis Hubbard wrote:
> Thanks John:
>
> I've known Alina as a friend and colleague since the early 80s on St.
> Croix. This was an excellent contribution at the time. I'm sure she would
> acknowledge that the idea of "local" has expanded, but you are right that
> we need more of this kind of measured but informed commentary.
>
> Dennis
>
> On Tue, May 1, 2018 at 6:38 AM, Bruno, John <jbruno at unc.edu> wrote:
>
>> Dear listers,
>>
>> Over the weekend I read, for the 3rd or 4th time, Alina Szmant’s (2002)
>> incredible review "Nutrient Enrichment on Coral Reefs: Is It a Major Cause
>> of Coral Reef Decline?” and wanted to share it with you.
>>
>> It’s an amazing paper and a good example of how to critically evaluate
>> evidence for a perceived impact. Very thorough and unbiased. You can
>> download it here:  https://www.dropbox.com/s/
>> q6j144vwzx66e2u/Szmant%202002.pdf?dl=0
>>
>>
>> Here’s the abstract:
>>
>> Coral reefs are degrading worldwide at an alarming rate. Nutrient
>> over-enrichment is considered a major cause of this decline because
>> degraded coral reefs generally exhibit a shift from high coral cover (low
>> algal cover) to low coral cover with an accompanying high cover and biomass
>> of fleshy algae. Support for such claims is equivocal at best. Critical
>> examination of both experimental laboratory and field studies of nutrient
>> effects on corals and coral reefs, including the Elevated Nutrient on Coral
>> Reefs Experiment (ENCORE) enrichment experiment conducted on the Great
>> Barrier Reef, does not support the idea that the levels of nutrient
>> enrichment documented at anthropogenically-enriched sites can affect the
>> physiology of corals in a harmful way, or for most cases, be the sole or
>> major cause of shifts in coral- algal abundance. Factors other than
>> nutrient enrichment can be significant causes of coral death and affect
>> algal cover, and include decreased abundance of grazing fishes by fishing,
>> and of grazing sea urchins to disease; grazing preferences of remaining
>> grazers; temperature stress that kills coral (i.e., coral bleaching) and
>> creates more open substrate for algal colonization; sedimentation stress
>> that can weaken adult corals and prevent coral recruitment; coral diseases
>> that may be secondary to coral bleaching; and outbreaks of coral predators
>> and sea urchins that may be secondary effects of overfishing. Any factor
>> that leads to coral death or reduces levels of herbivory will leave more
>> substrate open for algal colonization or make the effects of even low-level
>> enrichment more severe. Factors that contribute to an imbalance between
>> production and consumption will result in community structure changes
>> similar to those expected from over- enrichment. Over-enrichment can be and
>> has been the cause of localized coral reef degradation, but the case for
>> widespread effects is not substantiated.
>>
>>
>>
>>
>>
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>
>
>



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