New abstracts

James C. Hendee hendee at AOML.ERL.GOV
Mon Jul 10 09:46:37 EDT 1995

I am hoping that circulating new abstracts of coral health research  
will help keep list members abreast of current research.  If you object  
to this, please let me know. 

If you have abstracts that are not on our Literatures Abstracts page,  
and would like them included, please drop a line.  If you can send an  
e-mail message with the information, that would be much more easier to  
work with than a printed copy. 

Following are two new abstracts added to the CH&M World-Wide Web Home Page. 

	Sincerely yours, 

	Jim Hendee 

|  James C. Hendee              | Internet:     hendee at | 
|  Coral Health and             |                                   | 
|    Monitoring Program         | Voice:        305 361-4380        | 
|  Ocean Chemistry Division     | Fax:          305 361-4582        | 
|  NOAA/AOML                    | COASTAL RBBS: 305 361-4524        | 
|  4301 Rickenbacker Causeway   |                                   | 
|  Miami, FL  33149-1026        |         | 


Hoegh-Guldberg, O. 1994. The uptake of dissolved organic matter by the 
larval stages of the crown-of-thorns starfish Acanthaster planci. Marine 
Biology 120:55-63. 


The life-history of the crown-of-thorns starfish (Acanthaster planci) 
includes a planktotrophic larva that is capable of feeding on 
particulate food.  It has been proposed, however, that particulate food 
(e.g. microalgae) is scarce in tropical water columns relative to the 
nutritional requirements of the larvae of A. planci, and that periodic 
shortages of food play an important role in the biology of this species.  
It has been also proposed that non-particulate sources of nutrition 
(e.g. dissolved organic matter, DOM) may fuel part of the nutritional 
requirements of the larval development of A. planci as well.  The 
present study addresses the ability of A. planci larvae to take up 
several DOM species and compares rates of DOM uptake to the energy 
requirements of the larvae.  Substrates transported in this study have 
been previously reported to be transported by larval asteroids from 
temperate and antarctic waters.  Transport rates (per larval A. planci) 
increased steadily during larval development and some substrates had 
among the highest mass-specific transport rates ever reported for 
invertebrate larvae.  Transport rates for alanine increased from 15.5 
pmol larva-1h-1 (13.2 pmol mg-1h-1) for gastrulas (Jinmax = 38.7 pmol 
larva-1h-1 or 47.4 pmol mg-1h-1 ) to 35.0 pmol larva-1h-1 (13.1 pmol 
mg-1h-1) for early brachiolaria (Jinmax just prior to settlement = 350.0 
pmol larva-1h-1 or 161.1 pmol mg-1h-1) at 1 mM substrate concentrations.  
The instantaneous metabolic demand for substrates by gastrula, 
bipinnaria and brachiolaria stage larvae could be completely satisfied 
by alanine concentrations of 11 mM, 1.6 mM and 0.8 mM respectively.  
Similar rates were measured in this study for the essential amino acid 
leucine, with rates increasing from 11.0 pmol larva-1h-1 (or 9.4 pmol 
5g-1h-1) for gastrulas (Jinmax = 110.5 pmol larva-1h-1 or 94.4 pmol 
5g-1h-1) to 34.0 pmol larva-1h-1 (or 13.0 pmol mg-1h-1) for late 
brachiolaria (Jinmax = 288.9 pmol larva-1h-1 or 110.3 pmol 5g-1h-1) at 1 
mM substrate concentrations.  The essential amino acid histidine was 
transported at lower rates (1.6 pmol 5g-1h-1 at 1 mM for late 
brachiolaria).  Calculation of the energy contribution of the 
transported species revealed that larvae of A. planci can potentially 
satisfy 0.6 %, 18.7%, 29.9% and 3.3% of their total energy requirements 
(instantaneous energy demand plus energy added to larvae as biomass) 
during embryonic and larval development from external concentrations of 
1 mM of glucose, alanine, leucine and histidine respectively.  These 
data demonstrate that a relatively minor component of the DOM pool in 
seawater (DFAA) can potentially provide significant amounts of energy 
for the growth and development of A. planci during larval development.  


Hoegh-Guldberg, O. 1994. The population dynamics of symbiotic 
zooxanthellae in the coral Pocillopora damicornis exposed to elevated 
ammonia.  J. Pacific Science 48: 263-272.  


The division synchrony and growth rate of symbiotic 
zooxanthellae was investigated for populations living in colonies of the 
reef-building coral Pocillopora damicornis exposed to different 
concentrations of NH4Cl in seawater.  The presence of low concentrations 
of NH4Cl (0.2 5M) did not affect (compared to corals growing in 
NH4+-stripped seawater) either division synchrony or growth rate.  
Exposure to higher concentrations of NH4Cl (20 mM or 50 5M), however, 
affected the population dynamics of the zooxanthellae residing in P. 
damicornis.  Zooxanthellae in corals exposed to 20 5M NH4Cl had mitotic 
indices (the percentage of the total cells dividing) that were two to 
three times higher than the mitotic indices of zooxanthellae in control 
(0.2 5M) corals.  Although the division of zooxanthellae was still 
phased in corals exposed to 20 5M NH4Cl, there were many more cells 
dividing out of phase as compared to control corals.  The division of 
zooxanthellae in corals exposed to 50 5M was not phased.  The calculated 
growth rates of zooxanthellae exposed to 20 5M or 50 5M NH4Cl were 
higher than those representative of zooxanthellae living in control 
corals, although the growth rate of both carbon and nitrogen pools were 
lower in 50 5M as compared to 20 5M NH4Cl.  These data support the 
conclusion that the population dynamics of symbiotic zooxanthellae 
within P. damicornis are affected by concentrations of NH4Cl in seawater 
that are equal to or higher than 20 5M, and that 50 5M NH4Cl 
concentrations may be toxic to some extent.  These data taken in 
isolation, however, do not constitute an effective test of the 
hypothesis that zooxanthellae are limited by the supply of NH4Cl under 
ambient conditions, and further emphasize the importance of enrichment 
studies concentrating on growth and nitrogen incorporation rates 
measured for the entire symbiotic association.  

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