ICES Journal of
Marine Science
ICES Journal of Marine Science (2013), 70(7), 1294– 1298. doi:10.1093/icesjms/fst035
Original Articles
Coral recruitment: the critical role of early post-settlement survival
Stephane Martinez and Avigdor Abelson*
Department of Zoology, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
*Corresponding author: tel: +97236406936; fax: +97236406936; e-mail [email protected]
Martinez, S., and Abelson, A. 2013. Coral recruitment: the critical role of early post-settlement survival. – ICES Journal of Marine Science, 70:
1294 –1298.
Received 15 March 2012; accepted 19 February 2013; advance access publication 13 August 2013.
Coral recruitment is a pivotal factor in coral reef stability and in recovery following substantial disturbances. Despite its immense importance, the study of coral recruitment has some major gaps, notably larval survival before and following settlement, mainly due to technical
limitations, which stem from the difficulty in observing the minute larvae. To overcome the major limitation in coral recruitment studies,
i.e. the in situ detection of recruits during their early stages, we designed a new detection set-up, composed of a fluorescence detection
set-up, a grid-covered substrate, and a Geographic Information System tracking system. This set-up, enabling the identification of coral
recruits soon after settlement, revealed that in the critical period of the first day, less than 45% of the settling corals may survive. The
results also suggest that either coral larva select locations that may increase their survival chances or they experience dramatic mortality
during the early hours of settlement, which induce a consistent pattern of spat distribution. Our study confirms an earlier speculation that
the first 24 h post-settlement may determine the rates and spatial patterns of recruitment. The significant implications of these findings,
and the implemented “detection set-up” for coral reef monitoring and management, are discussed.
Keywords: corals, coral reefs, fluorescence, recruitment, resilience, settlement.
Introduction
Coral reefs worldwide are deteriorating due to diverse anthropogenic and natural disturbances (Fishelson, 1973; Jackson et al., 2001;
McCulloch et al., 2003; Bellwood et al., 2004; Loya, 2004).
Whereas reefs might be able to resist minor disturbances, the resilience of a coral reef ecosystem following major disturbance events is
determined by its ability to return to its previous state and to avoid
the replacement of corals by algae (West and Salm, 2003; Bellwood
et al., 2004). A key element in resisting change lies in adequate recruitment by reef-building corals (Bellwood et al., 2004).
Considerable knowledge has been acquired regarding coral reproduction (Harrison et al., 1984; Shlesinger and Loya, 1985;
Babcock et al., 1986; Richmond and Hunter, 1990) and recruitment
(Wallace et al., 1986; Richmond and Hunter, 1990; Abelson et al.,
2005; Baird et al., 2006). However, the critical early stages of recruitment, i.e. settlement of the larvae and their survival during the postsettlement, early days, are still poorly understood (Roth and
Knowlton, 2009).
To date, most coral recruitment studies have been carried out on
clearly visible coral recruits, mainly using settlement plates that
were inspected after a period of between 2 months to over 1 year
post-settlement (Wallace et al., 1986; Tomascik, 1991; Maidall et al.,
1995; Abelson et al., 2005; Price, 2010). This approach has been prevalent due to the corals’ minute size at settlement and their slow growth
rate, which hinder spat detection even with a stereoscopic microscope
during the 2-month period post-settlement (Babcock et al., 2003).
During this early period, mortality may be high and various settlement processes, which are part of the overall recruitment process of
the reef, might be missed (Keough and Downes, 1982; Babcock
et al., 2003; Baird et al., 2006) and, therefore, may lead to inaccurate
conclusions regarding the mechanisms of settlement and the population dynamics of corals (Keough and Downes, 1982; Baird et al.,
2006). To the best of our knowledge, larval settlement and coral survival during the first days of the recruitment process have not been
documented in the field. Utilizing a new detection set-up [corals’
fluorescence, grid-covered substrate, and Geographic Information
System (GIS)] enables us to study this gap between the initial phase
of larval attachment and the advanced stage of easily spotted coral
recruits. Bridging this gap can help us to better understand the difficulties inherent in ensuring appropriate coral reef resilience following
degradation and to help improve measures for management and
restoration.
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Coral settlement and recruitment
Material and methods
The field study was conducted in Eilat, northern Gulf of Aqaba, Red
Sea, between the Dolphin Reef Resort and the Port of Eilat
(29831.620′ N 34856.270′ E). Six experimental settlement modules
were composed of metal frames (1 m high × 2 m long × 1 m
wide); on top of which nine attached PVC troughs (made of
pipes, 1.5 m long and 0.15 m in diameter, which were cut lengthwise
to remove their upper quarter). The trough structure has been
chosen to enable various substrate orientations from horizontal to
vertical, while increasing the probability of larva interacting with
the substrate in laminar flow, similar to flow inside a cylinder
(Zilman et al., 2011). The settlement modules were deployed in
November 2006 and were laid on a sandy seabed, at a depth of
10 m. The inside of each trough was then coated with a galvanized
chicken net (1.2 cm mesh) and used as the basic settlement substrate. The chicken net served as x –y coordinates of the trough
surface for the exact detection of the spat location and as the x –y
2-dimentional matrix of the GIS. Three different types of settlement
substrates were created: “live troughs” (with live coral transplants),
“skeleton troughs” (with dead coral branches), and bare troughs
(without live or dead coral transplant). The settlement substrates
(troughs) were not cleaned of any fouling organisms nor were any
other maintenance action performed. Coral settlement was assessed
by detecting and documenting only coral spat inside the trough. To
avoid the influence of coral transplants on the settlement process
and survival, we limited our analyses to the 19 “no-treatment” substrates (“bare troughs”). However, for the spatial distribution along
the trough perimeter, we used all 54 substrates.
The chicken net inside the trough was used as a grid for determination of the exact local spatial (“geographic”) position of each coral
settlement (spat), i.e. by x –y coordinates. For the detection of new
settlement, night dives were conducted using a blue flashlight and
filter for the diving mask (model Blue Star and BlueBlock;
NightSea, Bedford, MA, USA). The blue lights enabled the detection
of newly settled corals that were less than 1 mm and 1-d old. This was
possible since many corals exhibit fluorescence even at the larval
stage (Fadlallah, 1983). The strong contrast between the black background and the green fluorescence made detection easy and reliable
(Piniak et al., 2005; Baird et al., 2006). To avoid any stress effects on
coral recruits, we did not remove the settlement substrates for laboratory identification of the coral spat. The confirmation/rejection, therefore, of traced spat was done by the inspection of shape,
movement, and white-light observations. To verify the firm attachment of the observed settled spat, a water stream was generated by
arm waving.
Sampling took place beginning in January (2 months after deployment), every 2 months, during 1 week after the full moon, for
the maximum larval settlement period (Shlesinger and Loya,
1985; Zakai et al., 2006). All modules were checked for new settlement over 4 consecutive days, enabling us to record coral recruits
from the first day of settlement and to monitor them for several
months. The exact location of each “old” (i.e. previously observed)
or “new” (first record) coral spat was documented daily, using the
x –y position grid of the chicken net. Nine months after the sampling
start and 45 d after the last sampling period (in September) in
October, an additional single sampling day was conducted to document the survival of young coral colonies since the September
survey. The settlement and survival data were assessed using a GIS
program (MapInfo Professional 7).
Coral larvae can settle and detach after 1 d (termed “reversible
metamorphosis”). Detachment can occur under unfavourable conditions for settlement (Richmond, 1985; Miller and Mundy, 2003).
It should, however, be noted that this phenomenon was not
observed in the field under natural conditions, and in the present
study, all disappearing spat were considered as “non-recruiting
spat”, regardless of their fate following disappearance.
The sampling procedure was based on the following considerations: (i) day 1 of sampling (Figure 1, day 1) could not provide
the exact age of the detected spat, since the exact timing of settlement
was unknown; therefore, this day was used as the zero point of each
sampling period (e.g. spat 1, 2, 3, 6, and 7 in Figure 1); (ii) during the
following days of sampling (days 2 –4; Figure 1), the timing of settlement could be determined to a resolution of 1 d; (iii) during days 2
and 3, it was possible to identify coral larvae that had settled but not
survived beyond 1 d (Figure 1, day 2, spat 8); (iv) spat that were
detected on day 4, but were not detected in the next sampling
period (Figure 1, day 4, spat 3 –5) were included in day 4; (v) spat
that survived from one sampling period to the next were considered
as 60-d old (Figure 1, day 60, spat 1 and 2); and (vi) the spat that survived more than two periods were included in an “over 60 d” (60+)
category and have not been considered in our analyses.
Results
Coral settlement and survival
In total, 309 coral settlers were observed during the year of surveys
for the 19 sample units (the “bare troughs”). Only 43% of the
detected settlers survived the first day, less than 27% survived 2
months, and a further decline in survival was observed after 1 year
(not presented). The average percentage of coral settlement and survival within a sampling period and between sampling periods is provided in Figure 2. There was a significant decline in the numbers of
coral [ANCOVA, p , 0.0001, F(df ¼ 1, 38), slope ¼ 20.0064) at all
sample units. There was no significant difference between the bare
trough over time [ANCOVA, p . 0.95, F(df ¼ 18, 38)]. The first
day of coral settlement significantly differed from the following
days (Wilcoxon matched pairs test, p , 0.001).
Coral distribution in the trough
The distribution of coral settlers was examined in all 54 troughs.
Since there were no significant differences in coral settlement and
Figure 1. Schematic chart of the sampling procedure for the age
assessment of coral spat and discrimination between coral settlement
and recruitment. The chart depicts a single settlement substrate during
a sampling period and between different sampling periods. Day 0 refers
to an empty trough with schematic grid inside. The trough centre,
which is the lowest part of the trough, is indicated in the axis as 0. NS,
new settlers.
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Figure 2. The average percentage of coral detected per day for a trough
(n ¼ 19). The first day (1) was set to 100% given that it was the day of
settlement on which survivorship began. Error bars are standard
deviation. For detailed explanation of sampling days refer to Figure 1.
Figure 3. Coral location on the pipe perimeter. The lowest part of the
trough is referred to as “0”, with the distance from the centre being
measured according to the number of the mesh cells (Figure 1). The 0
location was doubled to obtain the mirror-image effect. Diamond dots
indicate total coral settlement in all troughs (n ¼ 54); square dots
indicate surviving corals in all troughs (n ¼ 54). Survival was referred to
coral aged older than 45 d, which was the gap between sampling
periods at the end of the experiment. A positive correlation was seen
between the two (Pearson’s correlation, p , 0.05, R 2 ¼ 0.85).
survival rates between the different trough treatments and the location of settlement (two-way ANOVA, p . 0.05), all treatments were
pooled. Due to sampling frequency limitations, survival was referred to as coral aged older than 45 d, which was the gap between
sampling periods at the end of the experiment. There was settlement
preference for the centre (lower part) of the trough perimeter and
the avoidance of the overhang. Likewise, there was a positive correlation between the location of coral spat and their survival (Pearson’s
correlation, p , 0.05, R 2 ¼ 0.85; Figure 3).
Discussion
Most field studies on coral settlement/recruitment effectively
examine late stages of recruitment (over 2 months after settlement),
rather than the settlement process itself (Tomascik, 1991; Maidall
S. Martinez and A. Abelson
et al., 1995; Price, 2010). This limitation is due to the minute size
of settling coral larvae (Babcock et al., 2003), which typically
requires a minimum period of 2 months to over a year for the effective detection of coral recruits (Wallace et al., 1986; Tomascik, 1991;
Maidall et al., 1995; Abelson and Gaines, 2005; Abelson et al., 2005).
In the present study, settlement patterns, and dynamics of early stage
recruits of corals, were studied in the field, using a novel technique
which combines the use of fluorescence (for the efficient detection
of newly settled coral spat), a fixed grid (for accurate, repetitive spotting, and tracing of spat), and a GIS-based tracking system, allowing
us to record the exact location and timing of the settlement of coral
spat to a resolution of a few hours to a single day. Schmidt-Roach
et al. (2008) demonstrated that 97% of coral settlement is detectable
using the fluorescence method. Moreover, the technique enables
monitoring of the survival of newly settled coral recruits (i.e. early
settlers), thereby contributing further insight towards a better understanding of the entire process of coral recruitment. Although previous
studies, lacking the ability to detect initial recruitment, have assumed
that many early recruits do not survive (Keough and Downes, 1982;
Babcock et al., 2003; Baird et al., 2006), no study has actually examined this critical stage of the recruitment, nor provided any relevant
quantitative data. Bridging this gap in our knowledge is important
to minimize misconceptions regarding the potential role of recruitment in reef resilience and recovery potential and can help in planning
sound restoration approaches.
It should be noted that our findings are likely to be an underestimation of the actual recruitment rates, since some of the hard corals
present weak fluorescence and, in some cases, do not exhibit fluorescence at all (e.g. Porites sp.). However, the use of blue light is nonetheless highly reliable, since most of the Indo-Pacific reef-building
corals do display fluorescence (Baird et al., 2006). Furthermore,
the strong correlation between settlement site and location, in
which the corals were observed after more than 45 d when they
had reached a traditionally visible (without fluorescence) size of
one clear polyp or more (Figure 3), provides further support to
the assumption that the early detected spat were indeed coral
recruits. Although it might be an underestimation, the data still
revealed that over 55% of the detected corals that settled did not
survive the first 24 h (Figure 2). During the following days, the survival rate of newly settled corals continued to decrease, but not to the
extent of that of the first 24 h, and after 2 months, only a few corals
remained. The extremely less numbers of existing coral recruits after
2 months (7.4 spat opposed to 28.5 in the first day), in a relatively
wide sampling area (1 m2), demonstrate the problems of recruitment studies (which examine recruitment after 2 months or
more) in reflecting the actual settlement and survival processes
during the early settlement stages.
Based on our findings of the number of newly settled recruits, a
rough estimate of the numbers of settling corals can be calculated for
that year. From our obtained figure of 810 settlers in 22 sampling
days on a surface area of 31 m2, it can be estimated that the total
number of settlers on our study substrates could have reached
between ca. 8300 to over 13 000 settlers/year (267–419 in a
square metre). This wide range is based on two different calculations, both of which indicate dramatically higher settlement rates
than those previously noted by traditional field observations at
the same site (Glassom et al., 2004; Abelson et al., 2005). The first
is based on calculating the average settlement per day for the total
number of sampling days (a total of 810 new settlers during 22 d),
providing an average of 40 settlers/day and, therefore, over 365 d,
we obtain 13 438 settlers/year. A more conservative calculation is
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Coral settlement and recruitment
based on an average of 75 settlers/day during the high-reproduction
period (658 settlers for 8 d of sampling during the highreproduction period equals an average of 75 settlers/day) and an
average of 10.85 settlers/day during the rest of the year (200 settlers
over 14 d for the rest of the year). We can thus calculate 75 settlers/
day during the 60 d of the high-reproduction period, which
amounts to 4935 settlers. Adding the 10.85 settlers/day during the
remaining 300 d results in 3311 settlers and leads to a total of
8246 settlers/year.
Larval choice
Although the present study has added some further information
about settlement and early recruitment of coral larvae, it should
be stressed that even within the short duration of a “24-h settlement”, a significant portion of the settling larvae can disappear
soon after settlement, so that our figures may in fact be an underestimation of the actual number of early settlers. Strong circumstantial
support for such a scenario is provided by the dramatically higher
disappearance rates during the first detected day when compared
with the following second and third days, which suggests that the
early hours after settlement may be the most critical in terms of
settlement and survival. Assuming that the actual number of settlers
is significantly higher than the detected number of spat, the rates and
the spatial distribution of the settling larvae during the first 24 h
cannot be determined. However, the strong correlation between
the distribution of early detected spat and the distribution of surviving corals after 45 d (R 2 ¼ 0.85, p , 0.05; Figure 3) may indicate
that the survival chances of spat are the same in the different parts
of the troughs. An alternative explanation for the “apparently structured spatial distribution” of spat is that during the early hours of
settlement prominent mortality vectors (e.g. grazers, predators) selectively induce consistent patterns of spat distribution, which is
expressed in later stages and reflects the optimal microhabitats for
the settling corals. However, we believe that such equal survival
chances suggest that the observed distribution pattern after 24 h
reflects the settlement pattern, which, in turn, is most probably dictated by larval choice. Spatial distribution of settlement, dictated by
larval choice, can be induced by diverse settlement cues, such as
light, sedimentation, flow, and chemicals. Laboratory experiments
show advance phototactic responses which are not limited to
light/dark but also to spectral composition and light intensities
(Mundy and Babcock, 1998). Examinations of larval chemotaxis behaviour in the laboratory (Baird et al., 2003) and in the field (Suzuki
et al., 2008; Price, 2010) indicate that different chemical cues (e.g., by
biofouling and other organisms) can influence the settlement of
larvae. Roth and Knowlton (2009) describe the distribution, abundance, and microhabitat of small juvenile corals in the field and
demonstrate their settlement preferences. The above examples
suggest that the spatial distribution of recruits may be the result of
larval site selection rather than random choice. In the present experiment, stony corals seemed to prefer settlement on substrates
exposed to relatively stronger illumination and avoided the overhanging sides of the trough.
Conclusions
The settlement detection set-up applied in this study can improve
the resolution of coral recruitment detection, reducing it from a
scale of months to a scale of a single day or even hours. This significant time-scale refining enabled us to obtain records of early settler
survival, according to which over half of the corals did not survive
the first day.
The obtained data suggest that larvae may select their settlement
spots, thereby enhancing their chances of survival. Alternatively, the
observed spatial pattern can be the outcome of high mortality rates
during the first day (before the survey of first sampling day), which
dictates the first observed spatial pattern and which continues
during later stages of recruitment. Understanding the processes of
site selection for settlement by coral larvae, and their survival rates
during the initial stages, would require a fine, single-day resolution
of coral settlement surveys. The “detection set-up” applied in this
study can serve as a basis for the standardized monitoring system
of coral reef recruitment by providing an identical platform (i.e.
substrate) for the high-resolution identification of young spat in
early stages. The acquired knowledge of early recruitment stages
is crucial for a better understanding of coral reef conservation
and the implementation of sound management and restoration
approaches.
Acknowledgements
This study was supported by the Israel Science Foundation (ISF)
grant (funded by the Israeli National Academy of Humanities,
Arts and Sciences) and by the Red Sea Marine Peace Park
(RSMPP) program of the US agency for international development—Middle Eastern Regional Cooperation (USAID-MERC).
The authors thank Itzhak Benenson and Erez Hatna for their assistance using GIS which made this study possible and Ms N. Paz for her
editorial assistance. We would like to acknowledge the Dolphin Reef
managers, Nir Avni and Roni Zilber, and stuff for their support and
cooperation. We also thank Naomi Paz for editorial help, Karnit
Bahartan, Leor Korzen, Yarden Shani, Danniel Sharon, and Eyal
Takomi, for their assistance in the field, and the director and staff
of the Interuniversity Institute for marine sciences in Eilat for
their hospitality and the use of lab facilities.
References
Abelson, A., and Gaines, S. 2005. A call for a standardized protocol of
coral recruitment research and outlines for its conception. Marine
Pollution Bulletin, 50: 1745– 1748.
Abelson, A., Olinky, R., and Gaines, S. 2005. Coral recruitment to the
reefs of Eilat, Red Sea: temporal and spatial variation, and possible
effects of anthropogenic disturbances. Marine Pollution Bulletin,
50: 576– 582.
Babcock, R. C., Baird, A. H., Piromvaragorn, S., Thomson, D. P., and
Willis, B. L. 2003. Identification of scleractinian coral recruits from
Indo-Pacific reefs. Zoological Studies, 42: 211 –226.
Babcock, R. C., Bull, G. D., Harrison, P. L., Heyward, A. J., Oliver, J. K.,
Wallace, C. C., and Willis, B. L. 1986. Synchronous spawnings of 105
scleractinian coral species on the Great Barrier Reef. Marine Biology,
90: 379– 394.
Baird, A. H., Babcock, R. C., and Mundy, C. P. 2003. Habitat selection by
larvae influences the depth distribution of six common coral species.
Marine Ecology Progress Series, 252: 289– 293.
Baird, A. H., Salih, A., and Trevor-Jones, A. 2006. Fluorescence census
techniques for the early detection of coral recruits. Coral Reefs,
25: 73 – 76.
Bellwood, D. R., Hughes, T. P., Folke, C., and Nystroem, M. 2004.
Confronting the coral reef crisis. Nature, 429: 827– 833.
Fadlallah, Y. H. 1983. Sexual reproduction, development and larval
biology in scleractinian corals. Coral Reefs, 2: 129 – 150.
Fishelson, L. 1973. Ecology of coral reefs in the Gulf of Aqaba (Red Sea)
influenced by pollution. Oecologia, 12: 55– 67.
Glassom, D., Zakai, D., and Chadwick-Furman, N. E. 2004. Coral recruitment: a spatio-temporal analysis along the coastline of Eilat,
northern Red Sea. Marine Biology, 144: 641– 651.
1298
Harrison, P. L., Babcock, R. C., Bull, G. D., Oliver, J. K., Wallace, C. C.,
and Willis, B. L. 1984. Mass spawning in tropical reef corals. Science,
223: 1186– 1189.
Jackson, J. B. C., Kirby, M. X., Berger, W. H., Bjorndal, K. A., Botsford, L.
W., Bourque, B. J., Bradbury, R. H., et al. 2001. Historical overfishing
and the recent collapse of coastal ecosystems. Science, 293: 629 – 637.
Keough, M. J., and Downes, B. J. 1982. Recruitment of
marine-invertebrates—the role of active larval choices and early
mortality. Oecologia, 54: 348 – 352.
Loya, Y. 2004. The Coral Reefs of Eilat-Past, Present and Future: Three
Decades of Coral Community Structure Studies. Springer-Verlag,
Berlin, Heidelberg, New York.
Maidall, M., Sammarco, P. W., and John, C. 1995. Effects of soft corals
on scleractinian coral recruitment. I: directional allelopathy and inhibition of settlement. Marine Ecology Progress Series, 119:
191– 202.
McCulloch, M., Fallon, S., Wyndham, T., Hendy, E., Lough, J., and
Barnes, D. 2003. Coral record of increased sediment flux to the
inner Great Barrier Reef since European settlement. Nature, 421:
727– 730.
Miller, K., and Mundy, C. 2003. Rapid settlement in broadcast spawning
corals: implications for larval dispersal. Coral Reefs, 22: 99 – 106.
Mundy, C. N., and Babcock, R. C. 1998. Role of light intensity and spectral quality in coral settlement: Implications for depth-dependent
settlement? Journal of Experimental Marine Biology and Ecology,
223: 235– 255.
Piniak, G. A., Fogarty, N. D., Addison, C. M., and Kenworthy, W. J. 2005.
Fluorescence census techniques for coral recruits. Coral Reefs,
24: 496 –500.
Price, N. 2010. Habitat selection, facilitation, and biotic settlement cues
affect distribution and performance of coral recruits in French
Polynesia. Oecologia, 163: 747– 758.
Richmond, R. H. 1985. Reversible metamorphosis in coral planula
larvae. Marine Ecology Progress Series, 22: 181– 185.
S. Martinez and A. Abelson
Richmond, R. H., and Hunter, C. L. 1990. Reproduction and recruitment of corals—comparisons among the Caribbean, the Tropical
Pacific, and the Red-Sea. Marine Ecology Progress Series, 60:
185– 203.
Roth, M. S., and Knowlton, N. 2009. Distribution, abundance, and
microhabitat characterization of small juvenile corals at Palmyra
Atoll. Marine Ecology Progress Series, 376: 133 – 142.
Schmidt-Roach, S., Kunzmann, A., and Martinez Arbizu, P. 2008. In situ
observation of coral recruitment using fluorescence census techniques. Journal of Experimental Marine Biology and Ecology, 367:
37 – 40.
Shlesinger, Y., and Loya, Y. 1985. Coral community reproductive patterns—Red-Sea versus the Great Barrier-Reef. Science, 228:
1333– 1335.
Suzuki, G., Hayashibara, T., Shirayama, Y., and Fukami, H. 2008.
Evidence of species-specific habitat selectivity of Acropora corals
based on identification of new recruits by two molecular markers.
Marine Ecology Progress Series, 355: 149– 159.
Tomascik, T. 1991. Settlement patterns of Caribbean scleractinian corals
on artificial substrata along a eutrophication gradient, Barbados,
West Indies. Marine Ecology Progress Series, 77: 261– 269.
Wallace, C. C., Watt, A., and Bull, G. D. 1986. Recruitment of juvenile
corals onto coral tables preyed upon by Acanthaster planci. Marine
Ecology Progress Series, 32: 299– 306.
West, J. M., and Salm, R. V. 2003. Resistance and resilience to coral
bleaching: implications for coral reef conservation and management. Conservation Biology, 17: 956 – 967.
Zakai, D., Dubinsky, Z., Avishai, A., Caaras, T., and Chadwick, N. E.
2006. Lunar periodicity of planula release in the reef-building
coral Stylophora pistillata. Marine Ecology Progress Series, 311:
93 – 102.
Zilman, G., Novak, J., Liberzon, A., Perkol-Finkel, S., and Benayahu, Y.
2011. Role of self-propulsion of marine larvae on their probability of
contact with a protruding collector located in a sea current. http://
arxiv.org/abs/1108.1558
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