BULLETIN OF MARINE SCIENCE, 78(2): 377–388, 2006
CORAL REEF PAPER
Patterns of polychaete worm infestation
of stony corals in the northern Red Sea
and relationships to water chemistry
Jeffrey Wielgus, David Glassom, and Nanette E. Chadwick
Abstract
Coral reefs of the northern Red Sea are biodiverse and rich in endemisms, but also
fragile and susceptible to stress by natural and anthropogenic disturbances. Colonies of several genera of reef-building stony corals at Eilat (Israeli Red Sea) recently
have become infested with boring spionid polychaete worms, the presence of which
has induced skeletal aberrations on corals. Of 656 corals examined, 218 (33.2%)
were infested with boring spionid worms. The percent of infested coral colonies in
the coral genera Leptastrea and Porites was significantly correlated with the concentration of total oxidized nitrogen (TON, NO2 + NO3) in the water column. TON
levels also significantly predicted the likelihood of colony infestation in the corals
Leptastrea, Pavona, and Porites, and the likelihood of skeletal aberration in Porites.
High abundances of coral-boring polychaetes have been reported in other reef areas
close to organic waste discharges. We conclude that anthropogenic nitrogen enrichment of waters surrounding coral reefs at Eilat may have caused corals to become
vulnerable to infestation by boring spionid polychaetes, resulting in coral skeleton
aberrations and increased susceptibility to damage by storms.
The coral reefs at Eilat (Israeli Red Sea, 29°N) are situated near the northern limit
of reef building by scleractinian (stony) corals. These coral reefs are biodiverse and
rich in endemisms (Fishelson, 1995), and are exposed to a number of natural and anthropogenic disturbances. High levels of water circulation (Genin and Paldor, 1998)
disperse planktonic larvae along the coast, leading to the occurrence of stony corals
and other invertebrates throughout the coastline on shallow coral knolls (patch reefs)
and fringing reefs (Loya, 1990). The shallow reefs are affected by occasional winter
storms that cause surges of more than 10 m (Friedman, 1968), and dislodge a considerable number of corals (J. Wielgus, pers. obs.). Historically, organic inputs from
phosphate loading at the port, effluent from the adjacent town of Eilat, and oil spills
have impacted reefs in the area. There are signs that reefs have not fully recovered
from these events (Loya, 1990; Fishelson, 1995, Wielgus et al., 2003). Currently reefs
also are subjected to intense pressure from recreational SCUBA divers and snorkelers (Zakai and Chadwick-Furman, 2002). Coral cover at Eilat has declined markedly
in recent decades (Fishelson, 1995).
Two aquaculture facilities produce approximately 2000 t per year of gilthead seabream Sparus aurata (Linnaeus, 1758) (Porter et al., 1996) in cages located at the
northern Gulf of Eilat (Fig. 1). They release an estimated 18 × 106 mol N yr−1 into the
water column and are the largest source of N and P to the northern Gulf (Atkinson et
al., 2001), where the highest concentrations of inorganic nitrogen off the Eilat coastline are routinely found (B. Lazar, Hebrew University of Jerusalem, pers. comm.). The
effect on nearby coral reefs of nutrient enrichment by the aquaculture facilities has
been vigorously disputed. For example, Bongiorni et al. (2003) suggest that waste
from the fish cages does not affect coral health, while Loya and Kramarsky-Winter
(2003) argue that this source of nutrients is a major factor in coral reef deterioration
Bulletin of Marine Science
© 2006 Rosenstiel School of Marine and Atmospheric Science
of the University of Miami
377
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BULLETIN OF MARINE SCIENCE, VOL. 78, NO. 2, 2006
Figure 1. Location of five study sites and two floating fish farms (FF) at Eilat, northern Red
Sea. The Military Port was not examined in the preliminary survey, but was included in final
surveys.
at Eilat. Deep convective mixing also contributes to the eutrophication of surface
waters at Eilat between December and March (Lindell and Post, 1995), which are
considered the winter months.
It was recently observed that various scleractinian (stony) coral genera at Eilat have
become infested with spionid polychaetes (Wielgus et al., 2002). Some of these coral
colonies have developed aberrant growth forms consisting of projections of the coral
skeleton around the polychaete tubes (Fig. 2). Similar coral growth forms induced by
boring spionids have been documented in the Caribbean (Lewis, 1998) and the western Pacific (Liu and Hsieh, 2000). Boring spionids are among the most common coral
reef bioeroders, playing a substantial role in reef destruction (Hutchings, 1986), but
are found most frequently in coral rock or non-living substrata. To our knowledge,
the infestation of live coral colonies belonging to various genera at a single location
has not been reported previously.
Spionids construct interconnected tunnel networks within the coral skeleton that
project as mucus-lined openings on the surface (Lewis, 1998). These boreholes weaken
the coral colonies and increase their susceptibility to breakage by wave surge (Hein
and Risk, 1975; Scott and Risk, 1988). Spionid boreholes also are known to weaken the
shells of scallops and to increase their predation by lobsters (Bergman et al., 1982).
The abundance of coral-dwelling polychaetes has been positively correlated with
proximity to organic waste outfalls (Woodwick, 1964; Brock and Smith, 1983; Hutchings and Peyrot-Clausade, 2002). However, much of the work done on these worms
has concentrated on burrow architecture (e.g., Liu and Hsieh, 2000) or on different
aspects of polychaete biology including feeding ecology, recruitment, and successional patterns (e.g., Hutchings, 1986; Hentschel and Larson, 2005). Here we report
on the abundance of spionids and spionid-induced coral deformations on reef corals
at Eilat, and how these varied with the concentration of nitrogen in the surrounding
water column.
WIELGUS ET AL.: POLYCHAETE INFESTATION OF CORALS
379
Figure 2. (A) Close-up of a colony of the reef-building coral Montipora at Eilat, northern Red
Sea, with skeletal aberrations (wide arrows) resulting from coral growth around the tubes (thin
arrow) of boring spionid polychaetes. (B) A colony of the reef-building coral Porites with skeletal
aberrations indicated by arrows. The length of each arrow represents 5 cm.
Materials and Methods
Preliminary Survey of Polychaete Infestations.—During January 2002 we selected
four study sites along the coastline of Eilat (North Beach, Katzaa, Caves, and Taba) to examine
scleractinian corals infested with spionid polychaetes (Fig. 1). At a depth of 4–6 m at each site
we deployed a 50-m line transect around the perimeter of a coral knoll consisting of multiple
coral species, and recorded the genus of each scleractinian coral colony lying under the tape.
The hydrocoral Millepora (a non-scleractinian) also was included in the surveys because of its
important contribution to reef structure at Eilat (Loya and Slobodkin, 1971), and its susceptibility to infestation by spionids (Lewis, 1998). If the circumference of a knoll was < 50 m, the
tape was deployed to circumvent it at different distances from the bottom until a 50 m length
was achieved. We identified corals only to genus level because: (1) coral species are difficult to
identify underwater in the species-rich Red Sea region (Loya, 1972; Sheppard and Sheppard,
1991), and (2) genus-level ecological data on corals does not appear to result in significantly
higher variation among sites than does species-level data (Glassom, 2002). Each coral colony
was classified as either (1) not infested by spionid worms, or (2) infested (containing spionid
tubes). We also recorded the presence of coral aberrations, consisting of skeletal projections
around spionid tubes (Lewis, 1998; Liu and Hsieh, 2000; see Fig. 2). Spionid tubes are readily
differentiated from other boring polychaetes (sabellids, terebellids, serpulids) by their translucent appearance (Fig. 2A), and by standing above the surface of the corallite like tiny “chimneys” (Day, 1967). When feeding, worms protrude two palps that capture particulate organic
matter from the water column and/or the adjacent substrate (Rouse and Pleijel, 2001).
We collected two infested colonies of each of the coral genera Porites and Montipora for
the taxonomic identification of spionid worms. Coral skeletons were dissolved in 8% HCl, and
worms were stored in 70% ethanol. The preserved worms were sent to the Centre d’Estudis
Avançats de Blanes (Girona, Spain), where they were examined in a Hitachi S-3500N scanning electron microscope.
Abundance and Size of Infested Coral Colonies.—Between February and March
2002 we haphazardly selected three coral knolls at each site, adjacent to those examined in
the preliminary survey. In addition, three coral knolls were selected at a fifth site (Military
Port, Fig. 1). We extended a measuring tape around the perimeter of each knoll (range of knoll
circumference = 14–58 m), identified all stony coral colonies lying under the tape to genus
level, and estimated the mean projected diameter of each colony by measuring across the
colony center in three directions. We also recorded the presence of spionid tubes and associated skeletal aberrations for each measured coral colony.
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Nitrogen Measurements.—We used measurements of total oxidized nitrogen (TON,
NO2 + NO3) in our analyses because nitrogen is rapidly oxidized in coral reef waters and concentrates as nitrite and nitrate (Marubini and Davies, 1996).
Water samples were collected and analyzed by the Red Sea Marine Peace Park Program (see
Crosby et al., 2000) from each study site every 2–4 wks between September 1999 and August
2002. At each site, 31–46 water samples were analyzed. Water samples were collected from
the sea surface using a 5-l Niskin bottle (General Oceanics, Inc.). Concentrations of nitrate
and nitrite were measured following protocols in Grasshoff et al. (1999). Briefly, sulphanilamide was added to each seawater sample, and the azo dye that formed when it reacted with
nitrite in the sample was quantified using an Ultrospec 2100 UV/visible spectrophotometer.
To measure nitrate, granulated cadmium was added to reduce nitrate to nitrite, which then
was quantified as explained above. Total oxidized nitrogen (TON) was the sum of the nitrate
and nitrite present in each sample.
Statistical Analyses.—Logit regressions (Sokal and Rohlf, 1981) were conducted on all
coral genera (except for Astreopora, Echinopora, and Millepora, which were observed on only
one knoll at one or more sites) to test for the dependence of two factors: (1) the likelihood of
coral colony infestation, and (2) the likelihood of coral skeleton aberration, on: (1) mean diameter of coral colony, and (2) mean TON concentration (log (x + 1) transformed).
The TON data did not meet the homogeneity of variances requirement for ANOVA and regression analyses (Levene test), and therefore were log (x + 1) transformed. A three-way, type
3 sum-of-squares ANOVA was applied on the transformed data to test for variation in TON
concentrations with site, year, and season.
One-way ANOVAs were performed to test for differences in the percent infestation of coral
genera (except Astreopora, Echinopora, and Millepora, as explained above) among sites, and
in the level of coral skeletal aberration among sites. Percent data were used to account for
differences in coral abundance and area surveyed among the sites. Where differences were
significant, Tukey’s honest significant difference (HSD) tests for unequal samples were performed on the arcsine-transformed proportions. Stepwise regression analysis was conducted,
with the transformed proportion of coral colonies having infestations or skeletal aberrations
as the dependent variables, and TON concentration as the independent variable.
The statistical package Statistica 6.1 (StatSoft, Inc.) was used to perform ANOVA, postANOVA, logit regression, normality, and t-test analyses. Zar (1999) was followed for runs
tests. A level of P < 0.05 was considered significant in all test results.
Table 1. Genera of stony corals observed during a survey at Eilat, northern Red Sea. Genera
marked by an asterisk were infested by boring spionid polychaetes.
1
2
3
4
5
6
7
8
9
10
11
Coral genus
Acropora*
Alveopora
Astreopora
Cyphastrea*
Echinopora*
Favia
Favites
Galaxea
Goniastrea
Goniopora
Hydnophora
12
13
14
15
16
17
18
19
20
21
22
Coral genus
Leptastrea*
Lobophyllia
Millepora*
Montipora*
Pavona*
Platygyra
Plerogyra
Pocillopora
Porites*
Stylophora
Turbinaria
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WIELGUS ET AL.: POLYCHAETE INFESTATION OF CORALS
Table 2. Levels of infestation of stony coral genera by spionid polychaete worms at Eilat, northern
Red Sea. Aberrant colonies were those bearing skeletal deformations associated with spionid tubes
(see text for details).
Coral genus
Astreopora
Pavona
Montipora
Cyphastrea
Leptastrea
Millepora
Porites
Echinopora
All genera
Total # of colonies
7
41
76
125
98
50
222
37
656
# of infested colonies # of aberrant colonies % infestation
4
2
57.1
22
8
53.7
35
16
46.1
49
18
39.2
38
5
38.8
15
5
30.0
52
14
23.4
3
1
8.1
218
69
33.2
Results
From the 22 scleractinian coral genera observed during the preliminary survey,
eight were found to contain boring spionid worms (Tables 1, 2). In total, 656 coral
colonies from the eight infested genera were surveyed in this study, including 150
from the preliminary survey. Measurements of mean projected diameter were obtained from 506 colonies. Boring polychaetes in coral colonies collected at Eilat were
spionids belonging to a single species of the genus Dipolydora. This species apparently is a new member of the genus (J. Gil, Centre d’Estudis Avançats de Blanes, pers.
comm.). During field surveys, no obvious variation in tube size and structure was observed among the worms, so all were assumed to belong to the above species. Other
morphologically similar species may have been present at our study sites, although
only the above was found in the collected colonies.
In total, 218 coral colonies (33.2%) were infested with spionid polychaetes, and
69 colonies (10.5%) had skeletal aberrations (Table 2). There was a significant difference in percent infestation among sites (ANOVA, F = 24.56, 4 df, P < 0.0010), with
the North Beach and Military Port sites exhibiting the highest percent infestation
(Table 3).
All infested coral colonies had either a massive or encrusting growth form, as opposed to branching or foliaceous (Table 1). Porites and Cyphastrea were the most
abundant genera of infested corals (Table 2). The percent of infested colonies in EchiTable 3. Percent (mean ± 1SD) of coral colonies infested by boring spionid polychaetes at five sites
at Eilat, northern Red Sea, and concentration (mean ± 1SD) of total oxidized nitrogen (TON, N02 +
NO3). Nknoll is the number of coral knolls examined at each site, Ncoral is the number of coral colonies
observed at each site, and NTON is the number of water samples collected at each site. Vertical bars
join sites that were not significantly different in percent infestation (Tukey HSD test for unequal N on
arcsine-transformed percentages, 0.05 significance level) and mean TON concentration (Tukey HSD
test for unequal N on log (x + 1) transformed values, 0.05 significance level).
Site
Military Port
North Beach
Katzaa
Taba Terminal
Caves
% infestation
46.5 ± 5.9
59.0 ± 10.2
33.0 ± 2.4
31.2 ± 1.7
25.8 ± 0.96
Nknoll
3
4
4
4
4
Ncoral
102
118
165
140
131
TON (µM)
0.619 ± 0.508
0.448 ± 0.524
0.304 ± 0.347
0.269 ± 0.342
0.239 ± 0.311
NTON
46
31
46
46
33
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Table 4. Concentration (mean ± 1SD) of total oxidized nitrogen (TON, N02 + NO3) during summer
(TONsum, April–November) and winter (TONwin, December–March) at five sites at Eilat, northern
Red Sea. Nsum is the number of water samples collected at each site during summer; Nwin is the
number of samples during winter. Vertical bars join sites that were not significantly different in
mean TON concentration (Tukey HSD test for unequal N on log (x + 1) transformed values, 0.05
significance level).
Site
Military Port
North Beach
Caves
Katzaa
Taba Terminal
TONsum (µM)
0.599 ± 0.531
0.334 ± 0.238
0.150 ± 0.134
0.150 ± 0.152
0.148 ± 0.195
Nsum
31
18
21
31
31
TONwin (µM)
0.661 ± 0.470
0.628 ± 0.737
0.416 ± 0.446
0.623 ± 0.420
0.519 ± 0.443
Nwin
15
13
12
15
15
nopora (8.1%) was significantly lower than that of the next lowest infested genus,
Porites (23.4%) (χ20.05,1 = 9.1503, P < 0.0274).
TON concentrations (Tables 3, 4) varied significantly with site (ANOVA, F4, 162 =
4.44, P < 0.0020), year (F3, 162 = 6.10, P < 0.0006), and season (F1, 162 = 22.83, P < 0.0001).
The only interaction that was significant was year × season (F3, 162 = 4.30, P < 0.0022).
The average TON concentration was significantly higher at the Military Port than
at all other sites except the North Beach, and there were no significant differences
among the other sites (Table 3). In contrast, other environmental parameters monitored by the Red Sea Marine Peace Park Program (salinity, oxygen, pH, alkalinity)
did not differ significantly among sites (Table 5).
TON was a significant predictor of the likelihood of colony infestation in Leptastrea, Pavona, and Porites, but was not significant for the other coral genera examined
(Table 6A). TON also was a significant predictor of the likelihood of skeleton aberration in Porites (Table 6B), while colony size was not a significant predictor of either
colony infestation or skeletal aberration in any of the coral genera (Table 6A,B). There
was a significant relationship between TON concentration and the percent of infested colonies of the corals Leptastrea and Porites (Fig. 3). Statistical analyses were not
performed on data from Astreopora, Millepora, or Echinopora due to low numbers of
colonies of these genera at one or more sites. However, there was a trend of increased
infestation at higher TON levels in two of these coral genera (Fig. 3).
Table 5. Results of one-way ANOVAs to test for differences in log (x + 1) transformed values of
salinity, oxygen concentration, pH, and alkalinity at five sites at Eilat, northern Red Sea. Shown
are the non-transformed values (mean ± 1SD).
Site
Military Port
North Beach
Katzaa
Taba Terminal
Caves
Effect df
Error df
F
P
Salinity
40.687 ± 0.113
40.671 ± 0.102
40.768 ± 0.165
40.713 ± 0.116
40.724 ± 0.139
4
106
1.892
0.117
Oxygen (µM)
214.121 ± 5.994
213.183 ± 6.214
214.429 ± 6.578
211.416 ± 5.220
221.533 ± 0.000
4
65
0.797
0.532
pH
8.217 ± 0.027
8.208 ± 0.025
8.218 ± 0.026
8.210 ± 0.018
8.205 ± 0.016
4
155
1.660
0.162
Alkalinity
(meq/kg)
2.494 ± 0.035
2.489 ± 0.009
2.488 ± 0.012
2.490 ± 0.011
2.517 ± 0.101
4
142
1.892
0.115
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WIELGUS ET AL.: POLYCHAETE INFESTATION OF CORALS
Table 6. Results of logit regressions for (A) the likelihood of coral infestation by spionid
polychaetes, and (B) the likelihood of coral aberrations due to spionid polychaete infestation,
for five scleractinian coral genera at Eilat, northern Red Sea. Predictor variables were: (log (x
+ 1) transformed) total oxidized nitrogen (TON, N02 + NO3) and mean diameter of coral colony
(DIA). Significance of coefficients was tested with the Wald statistic; Pw is the P level of the Wald
statistic.
Coral genus
TON
A.
Cyphastrea
1.663
Leptastrea
4.488
Montipora
2.537
Pavona
6.115
Porites
3.876
B.
Cyphastrea
2.840
Leptastrea
−3.757
Montipora
1.132
Pavona
5.186
Porites
11.003
S.E.
Wald
Pw
DIA
S.E.
Wald
Pw
1.444
1.742
1.936
3.141
1.280
1.326
6.635
1.718
3.791
9.180
0.249
0.010
0.190
0.050
0.002
0.164
0.046
0.024
0.050
−0.001
0.019
0.032
0.018
0.034
0.006
0.727
2.108
1.850
2.182
0.006
0.394
0.147
0.174
0.140
0.936
2.170
3.566
2.188
3.540
4.914
1.711
1.110
0.267
2.147
5.013
0.191
0.292
0.605
0.143
0.025
0.013
−0.056
0.014
0.003
0.025
0.038
0.054
0.020
0.038
0.019
0.111
1.062
0.452
0.006
1.783
0.740
0.303
0.501
0.937
0.182
Discussion
The coral genera that we observed to be infested with boring spionid worms were
generally plocoid and with small polyps (Veron, 1986). These genera have a high coenosteum to corallite ratio, which may facilitate boring by providing a relatively large
surface area between polyps for excavation by worms. Kleeman (2001) found that the
boring pectinid bivalve Pedum favors coral hosts with small corallites (Montipora,
Porites, and Cyphastrea). In our study, coral colony size did not affect the probability
of infestation by spionid worms. Also, we confined our study to a depth range of
only two vertical meters, which was narrow enough to avoid issues of effects of coral
depth zonation (Loya and Slobodkin, 1971; Loya, 1972) on infestation patterns. All of
the coral genera observed here occur throughout the coastline (Loya and Slobodkin,
1971; Loya, 1972) and all sides of the coral knolls were examined (J. Wielgus, pers.
obs.), so all coral genera presumably were exposed to similar current patterns. Thus,
differences in exposure to currents also cannot explain the genus-specific infestation
patterns of these worms.
In the northern Red Sea, summer stratification of the water column (April–November) depletes nutrients from surface waters (Genin et al., 1995). However, we
found relatively high concentrations of total oxidized nitrogen (TON, NO2 + NO3)
during the summer months in the northern reaches of the Gulf of Eilat. This may be
a consequence of the oxidation of waste organic products from the fish farms, which
are the main source of anthropogenic nutrients to the northern Gulf (Atkinson et
al., 2001). The sea floor is located approximately 25 m below the cages, and mixing by
wind during the summer permits nutrients to reach the surface layers from this depth
(Genin et al., 1995). During the winter, when there is deep mixing and nutrients from
the non-photic layer reach the surface (Genin et al., 1995), all sites had higher TON
concentrations than in the summer. The northernmost sites still tended to have the
highest TON levels, although differences among sites were not significant.
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Figure 3. Variation in the percent of coral colonies of eight stony coral genera infested with spionid worms among five sites at Eilat, northern Red Sea. Horizontal bars join sites that were not
significantly different (Kruskal-Wallis multiple-comparisons test at 0.05 significance level). Statistical analyses were not conducted on coral genera marked with asterisks, due to low numbers
of colonies at one or more sites. Four coral knolls were surveyed at each site.
Other studies have observed that the abundance of boring polychaetes varies with
inorganic nutrient levels in the sea, including oxidized nitrogen (Nixon et al., 1984;
Frithsen et al., 1985). Levels of particulate organic matter also are known to correlate with polychaete abundance (Brock and Brock, 1977; Brock and Smith, 1983;
Hutchings and Peyrot-Clausade, 2002). Concentrations of organic nitrogen were not
WIELGUS ET AL.: POLYCHAETE INFESTATION OF CORALS
385
measured for the study sites, but the TON levels we report here may reflect oxidation
of dissolved organic matter.
Most studies on the effects of nutrient enrichment on corals have been conducted
under laboratory conditions, and have concluded that nutrient addition suppresses
coral calcification (reviewed in Koop et al., 2001). Marubini and Davies (1996) found
that concentrations of nitrate as low as 1 µM significantly reduced skeletogenesis,
and Kinsey and Davies (1979) observed reduced calcification with an experimental
dose of 20 µM urea + 2 µM phosphate. In contrast, other studies (e.g., Meyer and
Schultz, 1985, in the field; Atkinson et al., 1995, in a microcosm) have reported positive correlations between nutrients and coral skeletal growth. Increased calcification
rates may represent a metabolic cost to corals as energy is spent in excessive skeletogenesis (McConnaughey et al., 2000). Edinger et al. (2000) found that vertical extension rates of coral skeleton were the same in polluted and unpolluted sites in Java Sea
reefs, but that skeletal densities were lower in the former. They measured a net loss of
carbonate from the most polluted reefs, an indication of net reef erosion.
In the present study, TON was a significant variable explaining the likelihood of
infestation by spionid worms of the coral genera Leptastrea, Pavona, and Porites, and
the likelihood of coral skeletal aberrations in Porites. The highest mean TON levels
observed here (0.45–0.62 µM) may have enhanced calcification rates in Porites and
resulted in skeletal aberrations as the corals overgrew the protruding spionid tubes.
Porites is known to be one of the most porous of corals, and the presence of boring
organisms may further reduce its low skeletal strength (Scott and Risk, 1988).
Nitrogen is the primary limiting nutrient for primary production in many marine
ecosystems (Howarth, 1988; Muscatine et al., 1989), and anthropogenic nitrogen enrichment is causing changes in benthic marine communities worldwide (reviewed in
Carpenter et al., 1998), with coral reefs being especially vulnerable (Muscatine and
Porter, 1977). Coastal eutrophication in particular has been responsible for inducing trophic cascades that have altered the community structure of a wide range of
shallow, benthic environments (Pearson and Rosenberg, 1978; Lapointe et al., 2004),
including coral reefs (reviewed in McCook, 1999). Nutrient pollution can reduce the
fertilization rate of coral gametes and increase the incidence of embryo deformations (reviewed in Koop et al., 2001). It has also been correlated with bioerosion on
coral reefs (Rose and Risk, 1985; Pari et al., 1998; Holmes et al., 2000; Chazzottes et
al., 2002), resulting in increased impacts of natural disturbances (Hutchings, 1986).
At Eilat, current high infestation levels of corals by spionid worms may result in increased damage to reefs during storms.
Nutrient dynamics are complex, and determining nutrient thresholds for effects
on corals is difficult because of interactions among dissolved nutrients and other
coral stressors (Szmant, 1997). The association between nutrient levels and polychaete infestation described here is cause for concern. Our results highlight the need
for improved water quality in imperiled coral reef environments and for further information on how anthropogenic nutrient enrichment impacts the infestation of corals by boring organisms.
Acknowledgements
We thank J. Gil of the Centre d’Estudis Avançats de Blanes (Girona, Spain) for identification of polychaete specimens. Funding was provided by a Presidential Ph.D. Scholarship
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BULLETIN OF MARINE SCIENCE, VOL. 78, NO. 2, 2006
awarded to J. Wielgus by Bar-Ilan University and by the Red Sea Marine Peace Park Program
(sponsored by USAID-MERC and NOAA).
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Date Submitted: 23 June, 2005.
Date Accepted: 12 October, 2005.
Addresses: Faculty of Life Sciences, Bar Ilan University, Ramat Gan, Israel, and Interuniversity
Institute for Marine Science, P.O. Box 469, Eilat, Israel. Corresponding Author: (J.W.) Present Address: School of Life Sciences, Arizona State University, Tempe, Arizona 85287. Telephone: (480) 727-8178. E-mail: <[email protected]>. (D.G.) Present Address: Oceanographic Research Institute, P.O. Box 10712, Marine Parade 4056, Durban, South Africa. (N.E.C.)
Present Address: Department of Biological Sciences, 101 Rouse Life Sciences Building, Auburn
University, Auburn, Alabama 36849.