Planula Release Research Articles

First evidence of asexual recruitment of Pocillopora acuta in Okinawa Island using genotypic identification.

Okinawa Island is located near the center of the Nansei Islands (∼24–31°N), at a relatively high latitude for coral reefs. Nevertheless, more than 80 coral genera (over 400 species) are abundant in the Nansei Islands. Since March, 2017, scleractinian corals have been held in an outdoor tank at the OIST Marine Science Station at Seragaki, Onna with natural sea water flow-through in order to be used in molecular biological and physiological studies. In January, 2018, we found small pocilloporid-like colonies suspected to have originated asexually. We collected 25 small colonies and measured their sizes and weights. Also, we validated the classification and clonality of the colonies using a mitochondrial locus and nine microsatellite loci. Almost all of the small colonies collected in the outdoor tank were ≤1 cm in both width and height. The weight of dried skeletons ranged from 0.0287 to 0.1807 g. Genetic analysis determined that they were, in fact, Pocillopora acuta. Only one mitochondrial haplotype was shared and two microsatellite multilocus genotypes were detected (20 colonies of one and four colonies of the other). The mitochondrial haplotype and one microsatellite multilocus genotype for 20 colonies corresponded to those of one P. acuta colony being kept in the tank. One small colony matched both multilocus genotypes. This may have been a chimeric colony resulting from allogenic fusion. These small colonies were not produced sexually, because the only potential parent in the tank was the aforementioned P. acuta colony. Instead, they were more likely derived from asexual planula release or polyp bail-out. Corals as Pocillopora acuta have the capacity to produce clonal offspring rapidly and to adapt readily to local environments. This is the first report of asexual reproduction by planulae or expelled polyps in P. acuta at Okinawa Island.

First description of the life cycle of the jellyfish Rhizostoma luteum (Scyphozoa: Rhizostomeae).

Jellyfish blooms are a significant environmental problem that is increasing and may be influenced by anthropocentric practices such as overfishing, pollution, eutrophication, translocation, climate change, and ocean acidification. Many jellyfish have unknown life cycles leading to these blooms. We describe for the first time, the life cycle of scyphozoan jellyfish Rhizostoma luteum from the planula to the young medusa stages, based on laboratory observations. We also provide a preliminary assessment of temperature related to life stages. Comparisons were made with early life history stages of its sibling species Rhizostoma pulmo and Rhizostoma octopus. The life cycle of R. luteum follows the general pattern of metagenesis of scyphozoans. Scyphistoma culture was maintained in filtered seawater at 17–17.5 °C, salinity 37 and light photoperiod (12:12 h light:dark). Scyphistomae were exposed to an experimental temperature descent for two days to test their survival capacity under severe winter conditions. Only one asexual reproduction mode was observed, which is employed for propagation, consisting of podocyst formation with excystment, subsequent development of scyphistoma, strobilation and liberation of viable ephyra. The development of the ephyra to metaephyra was photodocumented, reaching the metaephyra stage in approximately 21–25 days. Young medusae grow rapidly and maturity was reached after a 3-month post-liberation period with a mean bell diameter of 13.27 ± 2.26 cm and wet weight of 181.53 ± 53 g. The life cycle of R. luteum resembles that of its congeners, with the distinction that it has the unique features of being a brooding species (internal fertilisation with subsequent release of planulae) and under the conditions tested, the predominantly strobilation type observed was monodisc, and not polydisc as with the other two species in the genus Rhizostoma. As R. luteum shows sufficient requisite to form blooms if environmental circumstances change, it is important to understand its life cycle.

The reproduction of the Red Sea coral Stylophora pistillata from Eilat: 4-decade perspective

Sexual reproduction characteristics of Stylophora pistillata, one of the most common coral species in the Gulf of Eilat, Red Sea, were extensively studied in the 1970s and 1980s. Four decades later, we examined possible changes in reproductive patterns in this species by placing planula traps over S. pistillata colonies during the 2015 and 2016 reproductive seasons. In total, 708 larval traps (222 traps in 2015 and 486 in 2016) were used, collecting 31,396 planulae overall (12,455 in 2015 and 18,852 in 2016). The results of this 2-year study indicated (a) lengthening of the reproductive season by up to 2 months (until mid-September 2015 and August 2016), (b) an extension of peaks in larval release from 2–3 to 5–6 months, (c) an increase in the percentage of colonies that release planula larvae, and (d) a high variability in larval release among different colonies and between consecutive collecting dates. All the above reflect decadal differences in the reproductive effort in S. pistillata. Furthermore, this study reveals that S. pistillata colonies stop releasing planulae after sea surface temperature (SST) reaches its annual peak, contrasting with the earlier finding that planula release ended before the annual SST peak. We propose that global change impacts and an increase in anthropogenic activities in the Gulf of Eilat are the culprit behind the reported changes in coral reproductive traits over the past 4 decades.

Reproductive biology of the deep brooding coral Seriatopora hystrix: Implications for shallow reef recovery.

Mesophotic coral ecosystems (MCEs, between 30 and 150 m depth) are hypothesized to contribute to the recovery of degraded shallow reefs through sexually produced larvae (referred to as Deep Reef Refuge Hypothesis). In Okinawa, Japan, the brooder coral Seriatopora hystrix was reported to be locally extinct in a shallow reef while it was found abundant at a MCE nearby. In this context, S. hystrix represents a key model to test the Deep Reef Refuge Hypothesis and to understand the potential contribution of mesophotic corals to shallow coral reef recovery. However, the reproductive biology of mesophotic S. hystrix and its potential to recolonize shallow reefs is currently unknown. This study reports for the first time, different temporal scales of reproductive periodicity and larval settlement of S. hystrix from an upper mesophotic reef (40 m depth) in Okinawa. We examined reproductive seasonality, lunar, and circadian periodicity (based on polyp dissection, histology, and ex situ planula release observations) and larval settlement rates in the laboratory. Mesophotic S. hystrix reproduced mainly in July and early August, with a small number of planulae being released at the end of May, June and August. Compared to shallow colonies in the same region, mesophotic S. hystrix has a 4-month shorter reproductive season, similar circadian periodicity, and smaller planula size. In addition, most of the planulae settled rapidly, limiting larval dispersal potential. The shorter reproductive season and smaller planula size may result from limited energy available for reproduction at deeper depths, while the similar circadian periodicity suggests that this reproductive aspect is not affected by environmental conditions differing with depth. Overall, contribution of mesophotic S. hystrix to shallow reef rapid recovery appears limited, although they may recruit to shallow reefs through a multistep process over a few generations or through random extreme mixing such as typhoons.

Population dynamics and factors controlling somatic degrowth of the common jellyfish, Aurelia aurita, in a temperate semi-enclosed cove (Kertinge Nor, Denmark)

Life expectancy of the scyphomedusa Aurelia aurita seems closely linked to seasonal shrinkage, or somatic degrowth, which occurs synchronously with sexual reproduction in temperate regions. In the present study, the mechanisms controlling body mass losses and subsequent disappearance of medusae were examined by following seasonal dynamics in population density, individual size, and sexual reproduction of A. aurita during 2013 and 2014 in the shallow, semi-enclosed Kertinge Nor, and the adjacent Great Belt, Denmark. After sexual maturation in early summer, medusae were characterized by a distinct phase of somatic degrowth, expressed by weight-specific individual growth rates of −0.5 to −1.4 % day−1, which was followed by the absence of A. aurita populations in both ecosystems during winter. The number of planula larvae per female (N L , ind.) was positively correlated with medusa diameter (d, mm), following the exponential relationship N L = 160.8 × e 0.029d . The percentage of body mass made up by planulae ranged from 6 to 11 % in Kertinge Nor and 10 to 33 % in Great Belt. ≤15 % of total size-specific body mass losses were due to the release of planulae in Kertinge Nor, suggesting shortage of zooplankton prey during autumn as main factor causing degrowth in A. aurita. Starving medusae produced significantly fewer oocytes and revealed increased mortality compared to well-fed individuals in supplementary laboratory experiments, indicating that degrowth controls the energetic investment into sexual reproduction. Seasonal variability in food supply, rather than energy allocation to reproduction, appears to shorten life spans of A. aurita medusae in temperate Danish waters.

Elevated temperature alters the lunar timing of Planulation in the brooding coral Pocillopora damicornis.

Reproductive timing in corals is associated with environmental variables including temperature, lunar periodicity, and seasonality. Although it is clear that these variables are interrelated, it remains unknown if one variable in particular acts as the proximate signaler for gamete and or larval release. Furthermore, in an era of global warming, the degree to which increases in ocean temperatures will disrupt normal reproductive patterns in corals remains unknown. Pocillopora damicornis, a brooding coral widely distributed in the Indo-Pacific, has been the subject of multiple reproductive ecology studies that show correlations between temperature, lunar periodicity, and reproductive timing. However, to date, no study has empirically measured changes in reproductive timing associated with increased seawater temperature. In this study, the effect of increased seawater temperature on the timing of planula release was examined during the lunar cycles of March and June 2012. Twelve brooding corals were removed from Hobihu reef in Nanwan Bay, southern Taiwan and placed in 23 and 28°C controlled temperature treatment tanks. For both seasons, the timing of planulation was found to be plastic, with the high temperature treatment resulting in significantly earlier peaks of planula release compared to the low temperature treatment. This suggests that temperature alone can influence the timing of larval release in Pocillopora damicornis in Nanwan Bay. Therefore, it is expected that continued increases in ocean temperature will result in earlier timing of reproductive events in corals, which may lead to either variations in reproductive success or phenotypic acclimatization.

Reproductive biology of the Caribbean brooding octocoral Antillogorgia hystrix

AbstractThe reproductive biology of the Caribbean gorgonian Antillogorgia hystrix was studied in the shallow‐water reefs of Cross Harbour, Great Abaco (The Bahamas) from 2009 to 2010. Antillogorgia hystrix is an internal brooder that reproduces annually. The population at Cross Harbour was gonochoric and the sex ratio was skewed toward females (~3:1). Oogenesis precedes spermatogenesis by several months, and lasts at least 9 months, with oocytes >100 μm in diameter first becoming visible in dissections of samples from February; mature oocytes are present in late October–November. The size of mature oocytes (400–900 μm in diameter) was greater than that of the spermaries, which were rarely larger than 400 μm. Brooded planulae were observed in polyps from early November to mid‐December, and planula release was observed in aquaria in December 2009, which suggests that planulation occurs continuously over this period. Planulae of A. hystrix contained dinoflagellate symbionts, presumably acquired during embryogenesis and/or by mature planulae while they were in the gastrovascular cavity of the polyp. Brooding is an uncommon reproductive strategy among Caribbean gorgonians and this is the first report of internal brooding in the genus Antillogorgia. The genus contains a number of sympatric species with different modes of reproduction, and knowledge of their reproductive biology is critical to understand their ecology and evolution.

Hourglass Mechanism with Temperature Compensation in the Diel Periodicity of Planulation of the Coral, Seriatopora hystrix

Brooding corals often exhibit daily planulation peaks in certain phases of lunar months during their reproductive season. The mechanism controlling this diurnal phenomenon, however, remains uncertain. Seriatopora hystrix populations of Southern Taiwan exhibit a highly synchronized planulation rhythm characterized by pre-dawn peak release episodes over a period of 4–6 days per month throughout the year. In this study, controlled light-dark cycles and temperatures were used to study the mechanism of the diel planulation rhythm in the laboratory. Seriatopora hystrix did not release planulae under continuous light or continuous darkness. Thus, the lack of free-run did not support a regulatory mechanism involving an endogenous oscillator. Under some lighting conditions, planula release occurred in two peaks per day. Both peaks always occur under dark phases of various light-dark cycles in the laboratory. The first peak occurred when the dark period just started, which might be stimulated by an abrupt transition between light and darkness. The second, pre-dawn peak consistently occurred 23 hrs after application of light. We concluded that this peak of planula release of S. hystrix was cued by sunrise of the previous day. Temperature treatments at 1°C intervals from 23.5–28.5°C did not change the diel time of planula release. We suggest that the temperature compensation exhibited in the hourglass model of this species may have a common origin as that of the oscillator model of circadian clocks, due to the similar duration (23 h) and period (∼24 h) between the two. The timing mechanism of planulation discovered here represents an intermediate stage between the hourglass and the oscillator models.

Planula release and reproductive seasonality of the scleractinian coral <I>Porites astreoides</I> in Bermuda, a high-latitude reef

Planula release from the scleractinian coral Porites astreoides Lamarck, 1816 at a high-latitude reef in Bermuda primarily occurred in the summer months of July and August, when the average seawater temperature for the lunar cycle preceding planulation exceeded 26.5 °C. Within the reproductive season in Bermuda, optimal planulation temperatures for P. astreoides are narrow. The release of fewer planulae was correlated with higher temperatures and there was significant variation in reproductive effort in colonies collected from sites across the 18-km wide Bermuda lagoonal seawater temperature gradient during this 2-yr study. The annual reproductive period of this species lengthens with a decline in latitude, which corresponds to a decrease in the range of annual seawater temperatures. Reproductive effort, as measured by the percentage of the population that is reproductive and number of planulae released per colony, is similar or slightly higher in Bermuda compared to conspecifics at lower latitudes. However, the shortened reproductive season results in a lower overall annual reproductive effort in Bermuda. Lunar synchrony of planula release peaked a few days before the new moon, slightly earlier than conspecifics in Florida, which peak during the new moon. Colonies from the Inner Lagoon peaked in planula release a few days earlier than those from other zones. We attribute spatial variation in lunar periodicity of planula release to differences in the timing of fertilization or planula maturation that may be influenced by environmental factors such as temperature and turbidity.

Diel planulation by the brooding coral Favia fragum (Esper, 1797)

Numerous studies addressing annual timing of planulation in scleractinians document a tightly synchronized process that coincides with lunar periodicity. In contrast, diel variation has received little attention, yet it may have important implications for post-metamorphic success. In summer 2006 and 2007, nightly release of planulae by Favia fragum was examined in Bermuda. Planulation occurred throughout the night with a significant peak between 04:00 hrs and 06:00 hrs. The effects of larval release time on settlement behavior, metamorphic success, in situ growth and mortality were also analyzed between larvae released from 22:00 hrs to 00:00 hrs (post-sunset) and 04:00 hrs to 06:00 hrs (pre-dawn) in July of 2007. The percentage of planulae observed testing the substrate for settlement at 4-hr intervals over 48 hrs post-release was significantly higher for those released pre-dawn than those released post-sunset. Additionally, percent metamorphic success after 48 hrs of exposure to a settlement tile was significantly higher for planulae released pre-dawn. Growth rates for pre-dawn planulae over 40 days post-release were initially significantly higher than post-sunset released planulae; however, this difference did not persist over time. Planulation near dawn and the resulting benefits are hypothesized to be a consequence of immediate exposure to light, which may provide increased energy from photoautotrophic symbionts, and also serves as a settlement cue inducing rapid settlement thereby aiding in predator avoidance and natal retention.

How the distribution of colonies of the hydroid Laomedea flexuosa is limited to a narrow belt along the lower littoral zone

In the White Sea the colonial hydroid Laomedea flexuosa inhabits a narrow belt of the lower littoral zone. How is so limited a habitat determined? We studied the time of planula release and the behaviour of larvae during the free-swimming stage and settlement in natural and laboratory conditions. Three methods were used to record the tidal-dependent dynamic of planula release: (1) plankton collecting bags around Fucus distichus macrophytes with mature hydroid colonies; (2) active stirring of Fucus with hydroids in a container with water, which is an old way to stimulate planula release; and (3) direct counts of the mature planulae in gonangia. The dynamic intensity of L. flexuosa planula release was investigated according to 3–4 phases of the tidal cycle. A moment of general release of larvae was shown to be correlated with a period of low water. Following the incoming tide keeps planulae in the littoral area. The planulae of L. flexuosa have a short period of swimming (less than 30 minutes), unlike those of Gonothyrae loveni and Dynamena pumila whose swimming period is about 36 hours. Quick settlement and tidal planula release could explain the strong spatial limitation in the distribution of L. flexuosa within the lower level of the intertidal zone. It is hypothesized that distribution over large areas is most likely by drift of colonies attached to detached seaweeds. Our outlook about the biological ways of ecological niche differentiation among marine organisms is broadened by the results of this study.

Timing of planulation by pocilloporid corals in the northwestern Philippines

We determined the lunar, seasonal, and diel timing of larval release in several species in the scleractinian family Pocilloporidae at Bolinao in the northwestern Philippines. All of the species exhibited remarkable lunar periodicity in planula release, with distinct timing in the lunar calendar. Despite confinement of peak larval release between the first quarter and full moons in 4 species (Pocillopora damicornis, P. verrucosa, Stylophora pistillata, and Seriatopora guttatus), only the 2 Pocillopora species experienced significant overlap in release times. Disparate lunar timing, on the other hand, was exhibited by the 3 Seriatopora species (new moon for S. caliendrum, last quarter moon for S. hystrix, and full moon for S. guttatus) during warm-dry months, although during seasons with low planulation rates the timing for the former 2 species seemed to overlap. Generally, lunar reproductive patterns in each species were seasonally consistent despite strong variations in larval output. The highest rates of planulation were recorded during the warm-dry months (March to May) and the lowest during the warm-wet months (June to October), except for P. damicornis, in which the lowest rate occurred during the cool-dry months (November to February). The timing of release in P. damicornis is mainly during the dark period of the diel cycle, with a peak at ca. 02:30 h. This report highlights the variation in timing of planulation among closely related coral species and compares temporal planulation data in the Philippines, which lies within the Indo-West Pacific center of coral diversity, to available data on brooding pocilloporid corals from other biogeographic regions.

Cycle of gonadal development in Eunicella singularis (Cnidaria: Octocorallia): trends in sexual reproduction in gorgonians

Abstract. Eunicella singularis is a gorgonian species whose members are abundant in hard‐bottom sublittoral communities of the Mediterranean Sea. The reproductive biology in this species has been examined to better understand the ability in this species to recover from recent mass mortality events. Eunicella singularis is a stable, gonochoric, iteroparous species that reproduces annually and exhibits a seasonal pattern of gametogenesis characterized by a single annual maturation of the gametes. The sex ratio did not significantly differ from 1:1. Oogenesis lasted 13–17 months, beginning between February and June, and ending with the release of 0.7 planula larvae per polyp between late May and July of the following year. The diameter of mature oocytes ranged 450–860 μm. Spermatogenesis was much shorter than oogenesis and occurred over 5–6 months. Gonadal production of both sexes increased in spring and culminated with the spawning of male colonies in late May–June. Fertilization of oocytes and development of the planula larvae occurred within the polyps of female colonies. Planula release was observed in June and July. The patterns emerging from this and previous studies on sexual reproduction of Mediterranean gorgonians suggest that investment in gonad development appears to be related to resource availability.

Reproductive ecology of the azooxanthellate coral Tubastraea coccinea in the Equatorial Eastern Pacific: Part V. Dendrophylliidae

The reproductive ecology of Tubastraea coccinea Lesson, an azooxanthellate tropical scleractinian coral, was studied over various periods from 1985 to 2006 at four principal eastern Pacific locations in Costa Rica, Panama, and the Galapagos Islands (Ecuador). This small (polyp diameter 0.8–1.0 cm), relatively cryptic species produced ova and planulae year round, including colonies with as few as 2–10 polyps. Of 424 colonies examined histologically, 13.7% contained both ova and sperm. Mature ova varied in diameter from ∼300 to 800 μm and the time from spawning and fertilization of oocytes to release of brooded planulae was about 6 weeks. Planulae were 0.5–1.5 mm long and they settled and metamorphosed on a variety of substrates after 1–3 days. Spermaries, though more difficult to distinguish in histological sections, were present throughout the year. Spent spermaries were never observed in sections, but several colonies in Panama and the Galapagos Islands released sperm from night one to night five after full moon, indicating the potential for cross-fertilization among colonies. Planula release was observed at Uva Island (Panama) in March, May, June, and July, and in general planula presence was higher at warm ocean temperatures at all sites, whether or not the sites were influenced by seasonal upwelling. Annual fecundity estimates for T. coccinea are comparable with other high fecundity brooding species, including the zooxanthellate Porites panamensis, with which it co-occurs in Panama. Tubastraea coccinea is widely distributed in the tropical Indo-Pacific and has colonized substrates in the western Atlantic. In addition to the reproductive characteristics described in the present study, other features of the biology of T. coccinea, such as an ability to withstand conditions that produce bleaching and mortality in zooxanthellate species, may account for its widespread, low-latitude distribution in multiple oceans.

Possible Self-Fertilization in the Brooding Coral Acropora (Isopora) brueggemanni

We examined gametogenesis and the periodicity of planula release in the brooding coral Acropora (Isopora) brueggemanni (Brook, 1893) on Akajima Island, Okinawa, Japan. We captured the moment when A. brueggemanni would be in the process of self-fertilization. Whole colonies of this species were cultured separately or together with other colonies in plastic containers. We observed no apparent periodicity of planula release in the collected colonies. A few planulae were released intermittently during the observation period, regardless of whether the colonies were cultured individually or with other colonies. Serial paraffin sections of A. brueggemanni showed follicle-like cells surrounding the oocyte during vitellogenesis. In September and October, some spermaries looked half-broken and some ova were surrounded by sperm or spermaries instead of follicle-like cells. Such ova were heart-shaped and may have been cells at the first cleavage stage. These observations suggest that the migration of spermaries and/or oocytes resulted in the close proximity of oocytes and sperm, which would allow self-fertilization. This possibility, together with the production of planula larvae by isolated colonies, suggests that this brooding coral engages in self-fertilization.

Diel patterns of larval release by five brooding scleractinian corals

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 321:133-142 (2006) - doi:10.3354/meps321133 Diel patterns of larval release by five brooding scleractinian corals Tung-Yung Fan1,2,*, Ke-Han Lin1,3, Fu-Wen Kuo1, Keryea Soong3, Li-Lian Liu3, Lee-Shing Fang1,2 1National Museum of Marine Biology and Aquarium, Pingtung, Taiwan 944, ROC 2Institute of Marine Biodiversity and Evolution, National Dong Hwa University, Hualien, Taiwan 974, ROC 3Institute of Marine Biology, National Sun Yat-Sen University, Kaohsiung, Taiwan 804, ROC *Email: tyfan@nmmba.gov.tw ABSTRACT: Timing of larval release in benthic marine invertebrates plays an important role in determining the reproductive success and extent of larval dispersal. Few studies have been conducted on diel variations in planula release by corals. Five brooding corals Seriatopora hystrix, Stylophora pistillata, Pocillopora damicornis, Euphyllia glabrescens, and Tubastraea aurea in Nanwan Bay, southern Taiwan, were selected to compare diel patterns of planula release. Corals were collected from the field and maintained in outdoor, flow-through systems to quantify the hourly release of planulae. Planulation by S. hystrix and S. pistillata was highly synchronized with 1 peak of planula release occurring close to sunrise. Planulae of P. damicornis and E. glabrescens were released throughout the day, and usually 2 peaks occurred in the early morning and at night. Planulation of the ahermatypic coral T. aurea occurred throughout the day without a consistent peak. The diel cycle of planulation for all 3 pocilloporids and E. glabrescens suggests that the light-dark cycle may be the cue that induces planula release. The majority of planulae of these 4 species being released in the dark might be beneficial for minimizing predation effects. The peak planulation occurring close to sunrise might be advantageous for exploiting light cues after sunrise by mature planulae in order to quickly settle, shortening the time they remain in the water column and promoting settlement within the natal reef. Variations in diel patterns of planula release show that variable strategies of reproductive timing exist for brooding species. KEY WORDS: Diel periodicity · Planulation · Coral · Seriatopora hystrix · Stylophora pistillata · Pocillopora damicornis · Euphyllia glabrescens · Tubastraea aurea Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 321. Online publication date: September 08, 2006 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2006 Inter-Research.

Lunar periodicity of planula release in the reef-building coral Stylophora pistillata

Stylophora pistillata is a dominant stony coral on reefs in the Red Sea, but the levels and periodicity of planula release in this coral are not well understood. We examined patterns of planula release by colonies under laboratory conditions in outdoor tanks at Eilat during 1998, then tagged and returned the corals to the adjacent reef. In 2003, we re-collected them and re-estimated their planula release patterns. In both years, the number of planula larvae released per night varied widely between colonies, and did not correlate with coral colony volume or diameter. Planula release rate per live coral volume was 5.6-fold lower in 2003 than in 1998, while coral volume increased 5.5-fold during this period. In both years, colonies of S. pistillata released planula larvae on a lunar cycle dur- ing the 4 mo of peak planulation (March to June). Peak release was on Night 6 following the full moon each month during 1998 and on Night 2 during 2003, with most planulation occurring between Nights 1 and 12. Collection of released planulae from randomly selected colonies of S. pistillata in the field during both years revealed the same lunar cycle of planula release as under laboratory condi- tions. In field colonies, the number of planulae released per coral was 3-fold lower in 2003 than in 1998. The observed reduction in planula release between years in the field parallels documented declines in coral recruitment and reef growth at Eilat, and may have resulted, in part, from anthro- pogenic impacts to local reefs. Added effects of coral aging in tagged experimental colonies may have caused the larger observed reduction in planula release observed under laboratory conditions. The proximate factors that regulate the above lunar periodicity of planulation are thought to include night irradiance patterns and tidal cycles, which also may be linked to gametogenesis cycles. Lunar periodicity ultimately may have developed to enhance the dispersal of released propagules during neap or spring tides, or to maximize fertilization of gametes through tight synchronization of coral reproduction among colonies.

Temporal settlement patterns of larvae of the broadcast spawning reef coral Favites chinensis and the broadcast spawning and brooding reef coral Goniastrea aspera from Okinawa, Japan

The faviid corals, Favites chinensis and Goniastrea aspera are widely distributed in the Indo-Pacific region. Both corals are hermaphroditic broadcast spawners, but G. aspera is also known to brood planula larvae in Okinawa. This study investigated the temporal settlement patterns of planula larvae of the scleractinian corals F. chinensis and G. aspera that developed from spawned gametes, and planula release and settlement of brooded larvae of G. aspera from Okinawa, Japan. Some of the broadcast-spawned larvae of F. chinensis and G. aspera had very short pre-competency periods of 1–2 and 2–3 days after spawning, and relatively long maximum settlement-competency periods of 56–63 and 63–70 days after spawning, respectively. These pre-competency periods are among the shortest reported for larvae of broadcast spawning coral species, and appear to be negatively correlated with seawater temperature. F. chinensis larvae tended to settle rapidly with 34–39% of larvae settling in the first week after spawning, while broadcast-spawned G. aspera larvae had a slower settlement pattern with 11–15% of larvae settling in the first week after spawning. Brooded larvae of G. aspera settled more rapidly, with settlement rates of 27–31% within the first 24 h and 45–65% within the first week after the start of the experiment. The production of planula larvae with rapid settlement capabilities may enable F. chinensis and G. aspera to establish and maintain populations in shallow reef sites at Okinawa. The release of the brooded planulae for up to 2 months may explain why G. aspera is locally more dominant on shallow reefs in Okinawa than F. chinensis. On a broader scale, the longer settlement competency periods of some of the broadcast-spawned larvae of these species increase their potential for longer-distance dispersal and may partly explain the wide biogeographic distribution of these species in the Indo-Pacific region.

Variation in planulae release of closely related coral species

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 247:75-84 (2003) - doi:10.3354/meps247075 Variation in planulae release of closely related coral species M. J. A. Vermeij1,2,3, E. Sampayo1, K. Bröker1, R. P. M. Bak1,2,* 1University of Amsterdam, IBED, PO Box 94766, 1090 GT, Amsterdam, The Netherlands 2Netherlands Institute for Sea Research (NIOZ), PO Box 59, 1790 AB Den Burg, Texel, The Netherlands 3Caribbean Marine Biological Insitute (CARMABI), Piscaderabaai z/n, PO Box 2090, Willemstad, Curaçao, Netherlands Antilles *Corresponding author. Email: rbak@nioz.nl ABSTRACT: To determine the degree of variation in coral reproductive strategies at a low taxonomical level, we studied the planulae release pattern in 4 Madracis morphospecies, including 2 colourmorphs of 1 species. All species have the same basic planulae release strategy: colonies of all species release planulae from March to December and spawning intensity fluctuates highly at a daily scale. Two differences exist among species. Firstly, species differ in the number of planulae released, ranging between 0.02 and 0.11 planulae cm-2 d-1. Secondly, spawning is not related to a moon-phase for any species except for M. senaria. During the last quarter moon in November, M. senaria releases large numbers of planulae (n > 1000). Mass release of planulae concurrent with the Caribbean mass spawning has never been reported previously for a brooding coral species. For all species examined the number of planulae produced is related to yearly seawater temperature cycles with a lag period of 1 mo, i.e. planulae production at any given month is related to the seawater temperature of the preceding month. Yearly temperature cycles dominate over lunar cycles in the regulation of planulation in Madracis spp. The number of planulae produced is not related to colony size in any species. The brooding reproductive strategy can be divided into 2 sub-strategies: (1) organized mass release, or (2) gradual release in low numbers without any conspicuous pattern. Our data show that small but significant differences exist in the reproductive strategies of closely related coral species, even at the level of colourmorphs, which differ in the fraction of spawning colonies in a population. KEY WORDS: Reproduction · Madracis · Planulae · Brooder · Coral · Caribbean · Life history Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 247. Online publication date: February 04, 2003 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2003 Inter-Research.

An Update on Modes and Timing of Gamete and Planula Release in Hawaiian Scleractinian Corals with Implications for Conservation and Management

Reproductive data for 24 of the 50 plus species of scleractinian corals in Hawai'i are available. A majority of species (75%) are broadcast spawners, just over half (58%) of which are hermaphrodites. Peak reproduction of Hawaiian corals occurs during summer months, although reproduction continues year-round for some brooders. Timing, duration, mode, and location of reproductive processes have implications for disturbance management, assessment, and conservation of reef corals.