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 aoml.erl.gov |
| 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 | http://coral.aoml.erl.gov |
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+
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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.
ABSTRACT.
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.
ABSTRACT
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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