487
RESEARCH
Lt I IRS
Mass Mortalityof the West-Indian
EchinoidDiademaantillarum
(Echinodermata:Echinoidea):A Natural
Experimentin Taphonomy
BENJAMINJ. GREENSTEIN
Departmentof Geology
Universityof Cincinnati
Cincinnati, OH 45221-0013
PALAIOS,1989, V. 4, 487-492
During1983, populationsof thecommon
long-spinedechinoidDiademaantillarum
weredecimatedbydiseasethroughoutthe
Caribbeanand asfar northas Bermuda.
The sudden incorporationof tests and
spines of large numbersof urchins into
surficialreefsedimentssuggeststhatsediment compositionmay be altered with
respectto the amountof echinodermmaterialpresent.Thehypothesisthata clear
recordof the mass mortalitymight be
preservedin the reef sedimentaryrecord
was testedat Bonaire, NetherlandsAntilles, wherethemortalitywas reportedto
haveoccurredin November,1983. Samples taken along a series of reefprofiles
and at specificdepthswithinsurficialreef
sedimentswereanalyzedfor totalechinoderm content and the proportionof the
echinoderm
fractioncomposedof skeletal
elementsof D. antillarum.The echinoderm fraction is virtually unchanged
from pre-mortalitylevels as reportedby
otherworkers.Echinodermsoverallare
minorcontributorsto reefsediments,and
skeletalelementsof Diademaaccountfor
a large proportionof the echinoderm
fraction. The lack of a strongsignal of
the eventdemonstratesthe inadequacyof
the reef sedimentaryrecordto preserve
this short-term,ecologicallysignificant
event.
INTRODUCTION
Prior to 1983, the long-spinedechinoid Diadema antillarum Philippiwas
often the dominantherbivorein tropical
Western Atlantic reef environments,
reachingdensities of 71 individualsper
square meter (Sammarco,1980; Hawkins and Lewis, 1982). As such, it was
responsiblefor large amountsof bioerosion while grazingalgae from reef surfaces (Scoffin et al., 1980; Hunter,
1977). Diademaalso prey on livingcoral
(Bak and van Eys, 1975; Carpenter,
1981); thus they contributed to the
controlof the coralcommunityas predators on coral recruits (Sammarco,
1980, 1982).
Beginningin January,1983, Diadema
suffered a widespread mass mortality
that was first observed at GaletaPoint,
Panama, and by January, 1984, had
spread to most of the Caribbeanand to
Bermuda (Lessios et al., 1984). The
causative agent is suspected to have
been a species-specific pathogen because the mortalityspread over such a
wide area withoutany dissipationof its
severity, and no other species of sea
urchin was affected (Lessios et al.,
1984). Whateverthe exact natureof the
disease, its effect was catastrophicon
Diadema populations, with mortality
rates of 98-100% in Curagao(Bak et
al., 1984), 94-99% in Panama(Lessios
et al., 1984) and 99% in Jamaica
(Hughes et al., 1985). Sharpincreases
in bottom cover by noncrustose algae
subsequentto the loss of Diademapopulationshave been documentedin Curagao (de Ruyter van Steveninck and
Bak, 1986), St. Croix (Carpenter,
1985) andJamaica(Hugheset al., 1985;
Liddelland Ohlhorst,1986).
The mass mortality occurred along
the fringingreefs of Bonaire, NetherlandsAntilles,in November, 1983 (Lessios, 1984). By August, 1984, only
broken, disarticulatedspines and test
plates were evident in surficial reef
sediments.
The sudden incorporationof innumerable urchins into reef sediments
suggests that sediment composition
may be altered by an increase in the
amountof echinodermmaterialpresent.
Frankel(1978) reported that mass outbreaksandsubsequentmass mortalities
of the Crown-of-ThornsstarfishAcanthasterplanci were preserved as layers
of sedimentenrichedin their ossicles on
the Great Barrier Reef. However,
Moranet al. (1986) demonstratedthat
Frankel'sdatawere insufficientto draw
that conclusion.The mass mortalityof
Diadema serves as a natural experiment in taphonomy;it provides an opportunity to assess the preservation
potentialof an event that continues to
have a profoundecological impact on
coral reef ecosystems in the Caribbean
and tropicalWestern Atlantic.
Here, I documentthe effect of Diademamass mortalityon sediment composition along the fringingreefs adjacent to Bonaire. Constituent particle
analyses of samples collected from a
series of reef slope profiles, and from
distinct intervals within surficial reef
sediments, reveal that the echinoderm
fraction shows no substantial enrichment above the pre-mortalitylevels as
reported by Kobluk and Lysenko
(1984). Although skeletal elements of
Diadema accountfor a large proportion
of the echinoderm fraction, no premortalitydata concerningthe percentage of Diadema skeletal elements in
reef sediments exist for comparison.
The lack of signatureof the mass mortality illustrates the inadequacyof the
near-reef sedimentary record to preserve the event.
STUDY SITE AND
SAMPLINGMETHODS
Samples were obtainedfrom four localities on the leeward side of Bonaire,
an island in the La Blanquilla-Aruba
chainthat parallelsthe South American
coastline (Fig. 1A). The profile of the
leeward fringing reef around Bonaire
consists of a narrowshelf from shore to
7-12 m depth, where the slope changes
abruptlyto a drop-offof 20-45 degrees
(KoblukandLysenko, 1984). The slope
again changes at 30-38 m depth, coral
diversity drops off and a sandy plain
slopes seawardat 5-15 degrees reach-
Copyright? 1989, The Society of EconomicPaleontologistsand Mineralogists 0883-1351/89/0004-0487/$1.50
488
GREENSTEIN
FIGURE--Area of study. Localities 1, 3 and 4 are reef slope profiles: locality2 is a sand
channel.
ing a maximumdepth between Bonaire
andKleinBonaireof 200 m (Bak, 1975).
In most places, the reef profileoccurs
as a series of buttresses separatedby
sand channels.
Surficialsediment samples were obtainedat 6 m depth intervalsdown the
reef slope at three localitiesanddowna
sand channel at one locality by a
SCUBA diver (Fig. 1B). Samples from
distinct horizons below the sedimentwater interfacewere obtainedfromtwo
adjacentareas at locality1 by means of
hole encasement with a calibrated
length of PVC pipe and use of an air lift
microscope to determine total echinoderm content and the proportionof the
echinodermfractioncomposed of skeletal elements of D. antillarum.Echinoderm grains can be recognized on the
basis of characteristicstructures (Fig.
2). For each sample, additionalquantities of the 500-1000 Ix size fraction
were impregnated with epoxy and
ground into standard thin sections,
which were point-countedon a 1 mm x
1 mm grid following the method of
Ginsburg(1956).
By evaluatingboth individualgrains
and thin sections, it was possible to
identifynot only distinctivefragments,
but also echinodermskeletal elements
that had been mechanically,chemically
or biologicallyreducedto grainsof highMg calcite lacking any characteristic
shape features. As a result, thinsection
point counts revealed consistently
higher echinoderm percentages than
graincounts because of the more accurate identificationof echinodermskeletal elements in polarizedlight.
Diadema skeletal elements have
characteristicmorphologiesthat permit
recognitionof spines, tubercles, teeth
and componentsof the Aristotle's Lantern and their distinctionfrom skeletal
elements of other echinoids (see
Durham and Melville, 1957; Philip,
1965 and Smith, 1984 for illustrations).
Because these morphologiesare rarely
present in thin section, only the echinoderm fractionsisolated by grain counting were analyzedfor the definitepresence of Diadema skeletal elements.
RESULTS
device similar to that described by
Shinn(1968) to remove sedimentdown
to specificdepths. To alleviatethe problem of mixingsediments from different
depth intervals, samples were obtained
from the encased hole at each specific
depth, rather than from the air lift device itself.
Samples were air-dried, sieved
through a stack of A.S.T.M. standard
sieves, and the 500-1000 ,L size fraction of each was split on an Otto microsplitter until sample sizes of 400-800
grains were obtained. The samples
were then analyzed with a binocular
Echinodermmaterialwas present in
the 500-1000 ,u sediment fraction as
completely disarticulatedskeletal elements. Overall, this material represented only a minor fraction of reef
sediments, composingfrom 0 to 7% of
the constituentsin each sample(Fig. 3).
Recognitionof trends is difficult,owing
to the exceedingly slight variation
within and between stations and low
overall percentages of echinodermmaterial.
Thin section point counts yield consistently higher values of echinoderm
percentages than graincounts (Fig. 3).
At locality 1, the echinodermfraction
increases between 6 and 12 m depth,
TAPHONOMY
ECHINOID
489
causes the coronato disarticulatealong
plate sutures. These findings, along
with those of Schafer (1972), suggest
that scavengers can greatly accelerate
disarticulationonce decay sets in. Lessios et al. (1984) reportedthat loss and
breakage of spines accompanied the
onset of the disease presumed to have
causedthe mass mortality.Additionally,
sick Diademaabandonedtheir day-time
cryptic habits and were consequently
attackedby fishes that do not normally
prey upon healthy individuals.Thus, it
is to be expected that individualsdying
during the mass mortality would be
incorporatedinto the reef sediments as
fragmentedremains.
Recognitionof the Mass Mortality
No echinodermenrichmentin surface
sediments occurred as a consequence
of the mass mortality.A comparisonof
FIGURE
2-Examples of characteristicmorphologieswith which echinoid skeletal elements
the results of this study with pre-morcan be recognized by analyzing individual grains. A) Skeletal elements of Diadema. B)
tality values obtained using similar
Skeletal elements of Echinometra, another common regular echinoid in Bonaire.
methods by Kobluk and Mielczarek
(1984) indicatesthat a slight increase in
the echinodermfractionhas occurredin
collected at the adjacent12 m excava4 out of 7 depth intervals (Fig. 5A).
declines at 18 m and increases to its
tionbut not by pointcounts (Fig. 4B). It
However, the overall percentages are
highest value at a depth of 36 m: the
should be emphasizedthat, as in reef
low and do not vary substantiallybebase of the reef slope (Fig. 3A). This
slope sediments, the echinodermfracdoes not occur at locality 2, the sand
tween the two studies. Skeletal eletion is quite small.
ments of Diadema compose a large
channel,where the echinodermfraction
Skeletal elements of Diadema acis highest at 18 m depth (Fig. 3B).
proportionof the echinodermfraction.
countfor a large proportionof the echiHowever, no dataexist concerningpreAverage percentages of echinoderm noderm fractions isolated
by grain mortality
materialare slightlyhigherin the chanproportionsof Diademain the
counting, averaging 32% and ranging sediment,
nel than at any reef slope locality.
makingit impossible to defrom 0 to 80%. Other echinodermretermine what effect, if any, the mortalPoint counts and graincounts reveal
mains include additionalregular echiity hadon their contribution.The lackof
conflictingvariationat locality 3 (Fig.
noids, crinoidsand ophiuroids.
an increase in the echinodermfraction
3C). The echinodermfractionincreases
overall indicates that no substantialinsteadily with depth in grain counts
DISCUSSION
crease in the amountof Diademamatewhereas it decreases to a depthof 24 m
rial could have occurred.
and then increases at 30 m in samples
BiostratinomicProcesses
Thus, it is highly unlikely that the
analyzedin thinsection. In thinsection,
The conditionof echinodermdebrisin
the amount of echinoderm material
slight increase in echinodermmaterial
reef sedimentsindicatesthat decay and
will constitute a recognizablesignature
present alongthe reef slope adjacentto
took place quicklyon the
disarticulation
of the mortalityin the reef sedimentary
KleinBonaire(locality4) decreases to a
sediment surface with subsequent inrecord. Rather, it may be the length of
depthof 18 m andthen increases at the
time before populationlevels return to
base of the reef slope (Fig. 3D). Grain corporationinto the sediment. Field
normalthat does so. Liddelland Ohlcounts reveal variationof 1%or less at
experiments with freshly killed Diadema specimens indicatedisarticulation horst (1986) suggested that the rate of
this locality.
of the test withindays in the absence of
recovery of Diadema populationswill
Analyses of sediments collected at
dictatethe impactof the mass mortality
specific intervals below the sediment- rapid burial (Greenstein and Meyer,
on the reef biota. This has been corrobwater interface suggest that whatever
1985). Moreover, I have observed that
Diademain aquariadisarticulaterapidly orated by various workers who have
variationthere may be in the amountof
as decay sets it. Spines fall off and the
documented a new coral-algalequilibechinodermmaterialis minor.Percentlanternand apicalsystem collapse into
riumthat is likely to remainas a result
ages increase slightlywith depth in the
the corona within a few days. In this
of the generally slow recovery of Dia10 m excavation (Fig. 4A). This was
also revealedby graincountsof samples
condition, the slightest disturbance dema populationsand the urchin'slow
490
GREENSTEIN
A
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B
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5
i4
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-U- GrainCounts
-+- Point Counts
6
0
3
C!
-H
.i
-HI
v
4
U
2
(AO
0\?
2 -
0
? ?
0
10
20
Water
Depth,
30
0
10
M
Water
? I
20
Depth,
I
?
30
M
D
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4 - -0- GrainCounts
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-+- Point Counts
a)
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4 -
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dS
1 -
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1 -
.
0
2-
.
.
.
.
10
Water
[
.
.
30
20
Depth,
M
I.
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10
Water
20
Depth,
30
M
FIGURE
3-Percentage of echinoderm materialversus depth at localities 1 through 4 (A
through D, respectively) as determined by grain counts and point counts. Locality 2 (B) is the
sand channel locality.
larvalrecruitmentrate (Bak, 1985; de
Ruyter van Steveninckand Bak, 1986;
Lessios, 1988). These observations
also applyto the signatureof the event
in coral reef sediments. The net effect
of the slow Diadema recovery may be
the depositionof an intervalessentially
barrenof theirremains(andthereforea
lower overall echinoderm fraction).
Thus, it may ultimatelybe the case that
a decrease, rather than an increase, in
Diadema content records the event in
reef sediments. However, both bioturbation and storm processes may well
obliterateany such signature. The latter point emphasizesthe inadequacyof
the reef environmentto preserve an
event that continuesto have a profound
impacton coral reef ecosystems in the
Caribbeanand tropicalWestern Atlantic.
Distributionof EchinodermMaterial
The distributionof live echinoids at
regular depth intervals along the reef
slope was determined by Kobluk and
Lysenko (1984) priorto the mass mortality. Live echinoid abundance decreased consistently with depth (Fig.
5B). The amountof echinodermmaterial in the sediment generallydoes not
reflect the distributionof live echinoids,
particularlyat the base of the reef
slope, where live echinoidabundanceis
lowest and the percent contributionof
echinodermsto the sediment increases
[Fig. 3A, C and D (delineatedby point
count data only)]. This suggests that
echinoderm skeletal elements are undergoinglimitedtransportand accumulatingat the base of the reef slope. The
channel sediment represents an amalgam of shelf and reef slope material.
Moreover, the echinoderm fraction is
composed of other common reef echinoderms and wouldnot be expected to
mirrorthe distributionof a single echinodermgroup.
Figure 4 suggests that no "echinoderm spike" exists within surficialreef
sediments; if such an enrichmentwas
ever present, it probablydisappeared
quicklyas a consequence of the bioturbationthat occurs along the reef profile
(Koblukand Lysenko, 1984).
Implicationsfor EchinoidFossil
Record
The lackof a clearmortalitysignature
in reef sediments underscores the rapidity with which populationsof Diadema have been reduced to essentially
unrecognizablecarbonate sand grains.
Although less than one year elapsed
between the time of mortality(November, 1983) and the time of sampling
(August, 1984), the potentialrecord of
the event has been lost. However, wellpreserved diadematoidechinoids have
been described. Aslin (1968) demonstrated that well preserved specimens
of the regular salenioid Acrosalenia
from the Middle Jurassic were preserved because of a rapidburialevent.
Rosenkranz(1971) invoked rapidsedimentationand the differingabilities to
escape it as responsible for producing
echinoidlagerstatten.Bloos (1973) suggested that rapidburialentombed individualsof the MiddleJurassic pedinoid
Diademopsis.This emphasizes the likelihoodthat well-preserved fossil diadematoid assemblages probably reflect
truly extraordinarytaphonomicevents.
CONCLUSIONS
1. The mass mortality has not resulted in an echinoderm-richhorizon in surficialreef sediments, nor
is the amountof echinodermmaterial in the sediment markedly
greater than that reported by Kobluk and Lysenko (1984) prior to
the mortality.
ECHINOID
TAPHONOMY
491
B
A
Geology, University of Cincinnati.Eric
Newton and the staff of the Karpata
EcologicalCenter of the Marine Park,
Bonaire made this study possible by
providing excellent facilities and services. I thank Dave Meyer for assistance in the field and for reviewing the
manuscript,Arnie Miller for reviewing
several draftsof the manuscript,Wayne
Pryor for assistance with sedimentologic analyses, and Janet Lauroesch for
assistance in preparingthe manuscript
and illustrations.
3 -*(U
2
2-
'0
o
C
-,c
C
0
Grain Counts
Point Counts
U
1-
do
1
0
20
30
Sediment,
cm
10
Depth
in
I
10
0
I
in
Depth
I
20
Sediment,
REFERENCES
cm
of echinoderm material versus depth at specific horizons within
FIGURE4-Percentage
surficial sediments. A) Excavation in 10 m of water. B) Excavation in 12 m of water. Note that
both excavations occurred adjacent to locality 1.
A
B
5 4 -
3 -o- This Study
-4- Kobluk & Mielczarek, 1984
'0
a)
o0
-C
--4
0
3 -
BAK,R.P.M., CARPAY,
M.J.E., and DERUYTER
VANSTEVENINCK,1984, Densities of the sea
2 -
0
r.
C
2 -
u4
1-
1.
0
.
10
Water
.
.
.
20
Depth,
.
30
M
n
10
20
Water
30
Depth,
M
FIGURE5-A) Comparison of the results of this study with those obtained by Kobluk and
Mielczarek (1984) prior to the mass mortality. Both curves were generated using average
percent echinoderm determined from three reef slope localities. Values in both studies were
obtained by point counting. B) Distribution of living echinoids versus depth (Kobluk and
Lysenko, 1984).
2. Preservationof the mass mortality
may be contingenton the slow rate
of recovery of Diadema populations, although it is unlikely that
slightincreases or decreases in the
echinodermfraction could be observed in a stratigraphicsuccession.
3. Once dead, individualsof Diadema
disarticulaterapidlyas a result of
biostratinomicprocesses. They are
then incorporatedinto surficialreef
sediments as fragmentedremains.
4. Echinoderm material undergoes
ASLIN,
C.J., 1968,Echinoidpreservationin the
Upper EstuarineLimestoneof Bilsworth,
Northamptonshire:
GeologicalMagazine,
v.105, p.506-518.
BAK,R.P.M., 1975, Ecologicalaspects of the
distribution
of reefcoralsinthe Netherlands
Antilles:Bijdragen
tot de Dierkunde,v. 45,
p. 181-190.
BAK,R.P.M., 1985, Recruitment
patternsand
mass mortalitiesin the sea urchinDiadema
antillarum:Proceedingsof the FifthInternationalCoralReef Congress,Tahiti,v. 5,
p. 267-272.
limited transportalong sand channels to the base of the reef slope;
the distributionof echinodermskeletal elements does not reflect that
of the livingechinoidfauna.
5. An "echinodermspike"in the fossil
record may well record highly unusual mass mortalities and rapid
coincidentor subsequentburial.
ACKNOWLEDGMENTS
This researchwas supported,in part,
by a grant from the Department of
urchinDiademaantillarumbeforeandafter
mass mortalitieson coralreefs in Curacao:
MarineEcologicalProgressSeries, v. 17,
p. 105.
BAK,R.P.M., and VANEYS,G., 1975, Predation of the sea urchinDiademaantillarum
Philippion livingcorals:Oecologia(Berlin),
v. 20, p. 111-115.
BLOOS,
G., 1973, Ein fundvon seeigeln der
GattungDiademopsisaus dem Hettangium
undihr Lebensraum:StuttWuiirttembergs
garterBeitr. Naturk.,v.(B)5, p.1-25.
CARPENTER,R.C., 1981, Grazing by Diadema
antillarum(Philippi)andits effects on the
benthicalgalcommunity:
Journalof Marine
Research,v. 39, p. 749-765.
R. C., 1985, Sea urchinmass morCARPENTER,
talities: effects on reef algal abundance,
species composition,and metabolismand
othercoralreef herbivores:Proceedingsof
the Fifth InternationalCoral Reef Congress, Tahiti,v. 4, p. 53-60.
DE RUYTER
VANSTEVENINCK,
E.D., and BAK,
R.P.M., 1986, Changesin abundanceof
coral-reefbottom componentsrelated to
mass mortalityof the sea urchinDiadema
antillarum:MarineEcologicalProgressSeries, v. 34, p. 87-94.
DURHAM,
J.W., and MELVILLE,R.V., 1957, A
classification
of echinoids:Journalof Paleontology,v. 31, p. 242-272.
FRANKEL,E., 1978, Evidencefromthe Great
BarrierReef of ancientAcanthasteraggregations,in Smith,S.V., ed., AtollResearch
Bulletinv. 220, CoralReef Ecosystems,
492
Proceedings of papers presented at the
13th Pacific Science Congress, Vancouver,
p. 75-93.
GINSBURG,
R.N., 1956, Environmentalrelationships of grain size and constituent particles
in some south Floridasediments: American
Association of Petroleum Geologists Bulletin, v. 40, p. 2384-2387.
GREENSTEIN,
B.J. & D.L. MEYER,1985, Mass
mortality of the West Indian echinoid Dia-
demaantillarum:A naturalexperimentin
taphonomy: Geological Society of America
Abstracts with Programs, v.17(7), p.598.
HAWKINS,
C.M., and LEWIS,J.B., 1982, Ecological energetics of the tropical sea urchin
DiademaantillarumPhilippiin Barbados,
West-Indies: Estuarine Coastal and Shelf
Science, v. 15, p. 645-689.
HUGHES,
T.P., KELLER,
B.D., JACKSON,
J.B.C.,
and BOYLE,M.J., 1985, Mass mortality of
the echinoidDiademaantillarumPhilippiin
Jamaica:Bulletin of Marine Science, v. 36,
p. 377-384.
HUNTER,I.G., 1977, Sediment production by
Diademaantillarumon a Barbadosfringing
reef: Proceedings of the Third International
Coral Reef Symposium, Rosenstiel School,
University of Miami, Miami, Florida, v. 2,
p. 105-110.
KOBLUK,D.R., and LYSENKO,
M.A., 1984,
Carbonate rocks and coral reefs, Bonaire,
Netherlands Antilles: Geological Association of Canada,MineralogicalAssociation of
GREENSTEIN
CanadaJoint AnnualMeeting Field Trip 13,
67 p.
KOBLUK,D.R., and MIELCZAREK,
W., 1984,
Sediment, in Kobluk, D.R., and Lysenko,
M.A., eds., Carbonate rocks and coral
reefs, Bonaire, Netherlands Antilles: Geological Association of Canada,Mineralogical
Association of CanadaJoint AnnualMeeting
Field Trip 13, 67 p.
LESSIOS,H.A., 1988, Population dynamics of
PHILIP,
G.M., 1965, Classificationof echinoids:
Journal of Paleontology, v. 39, p. 45-62.
ROSENKRANZ,
D., 1971, Zursedimentologie und
Okologie von echinodermen-lagerstatten:
Neues Jahrbuchfur Geologie und Palaontologie Abhandlungen,v.138, p.221-258.
SAMMARCO,
P.W., 1980, Diadema and its relation to coral spat mortality: grazing competition, and biologicaldisturbance:Journalof
Experimental Marine Biology and Ecology,
Diademaantillarum(Echinodermata:
Echiv. 61, p. 245-272.
noidea) followingmass mortalityin Panama:
SAMMARCO,
P.W., 1982, Echinoid grazing as a
Marine Biology, v. 99, 515-526.
structuring force in coral communities:
LESSIOS,
H.A., CUBIT,J.D., ROBERTSON,
D.R.,
whole reef manipulations:Journalof ExperM. R., GARRITY,
SHULMAN,
M.J., PARKER,
imental Marine Biology and Ecology, v. 61,
S.D., and LEVINGS,
S.C., 1984, Mass morp. 31-55.
talityof Diademaantillarumon the CaribSCHAFER,
W., 1972, Ecology and paleoecology
bean coast of Panama:Coral Reefs, v. 3, p.
of marine environments, Oliver and Boyd,
173-182.
London, 568 p.
LESSIOS,
H.A., ROBERTSON,
D.R., and CUBIT,
SCOFFIN,
T.P., STEARN,C.W., BOUCHER,
D.,
J.D., 1984, Spreadof Diademamass morFRYDL,P., HAWKINS,
C.M., HUNTER,
I.G.,
tality through the Caribbean: Science, v.
and MACGEACHY,
J.K., 1980, Calcium car226, p. 335-337.
bonate budget of a fringingreef on the west
LIDDELL,
W.D., and OHLHORST,
S.L., 1986,
coast of Barbados, II, Erosion, sediments,
Changes in benthic communitycomposition
and internal structure: Bulletin of Marine
following the mass mortality of Diadema at
Science, v. 30, p. 475-508.
Jamaica: Journal of Experimental Marine
SHINN,E.A., 1968, Burrowing in Recent lime
Biology and Ecology, v. 95, p. 271-278.
sediments of Florida and the Bahamas:
MORAN,P.J., REICHELT,
R.E., and BRADBURY,
Journalof Paleontology, v. 42, p. 879-894.
R.H., 1986, An assessment of the geological
evidence for previous AcanthasteroutSMITH,A., 1984, Echinoid Palaeobiology, Spebreaks: Coral Reefs, v. 4, p. 235cial Topics in Palaeontology 1, George Allen
238.
and Unwin, London, 190 p.