https://www.cell.com/current-biology/pdf/S0960-9822(12)01138-4.pdf

The magnitude of global marine species diversity

Corals of the world

Sexual reproduction by scleractinian reef corals is important for maintaining coral populations and evolutionary processes. The ongoing global renaissance in coral reproduction research is providing a wealth of new information on this topic, and has almost doubled the global database on coral reproductive patterns during the past two decades. Information on sexual reproduction is now available for 444 scleractinian species, and confirms that hermaphroditic broadcast spawning is the dominant pattern among coral species studied to date. Relatively few hermaphroditic or gonochoric brooding species have been recorded. Multispecific coral spawning has been recorded on many reefs, but the degree of reproductive synchrony varies greatly within and among species at different geographic locations.

/pdf/sexual-reproduction-of-scleractinian-corals-4xjukmnwx4.pdf

Sexual Reproduction of Scleractinian Corals

Coral mortality has increased in recent decades, making coral recruitment more important than ever in sustaining coral reef ecosystems and contributing to their resilience. This review summarizes existing information on ecological factors affecting scleractinian coral recruitment. Successful recruitment requires the survival of coral offspring through sequential life history stages. Larval availability, successful settlement, and post-settlement survival and growth are all necessary for the addition of new coral individuals to a reef and ultimately maintenance or recovery of coral reef ecosystems. As environmental conditions continue to become more hostile to corals on a global scale, further research on fertilization ecology, connectivity, larval condition, positive and negative cues influencing substrate selection, and post-settlement ecology will be critical to our ability to manage these diverse ecosystems for recovery. A better understanding of the ecological factors influencing coral recruitment is fundamental to coral reef ecology and management.

http://sotkae.people.cofc.edu/marineinverts/2009%20Ritson-Williams.pdf

New perspectives on ecological mechanisms affecting coral recruitment on reefs

Treatise on Marine Ecology and Paleoecology, Paleoecology, Vol. 2. Geological Society of America, Washington (1957)

We examined the effects of elevated temperature under different exposure periods on larval settlement and post-settlement survival in scleractinian corals, Acropora solitaryensis and Favites chinensis. In the first experiment with the subtropical coral, A. solitaryensis, the numbers of larvae settling and those dead were examined daily for 5 days at 20, 23 (ambient), 26 and 29°C conditions. Larval settlement of A. solitaryensis was initially greater at higher temperature conditions, but the peak in number of settled larvae shifted from 29 to 26°C by day 5, due to ca. 90% post-settlement mortality at 29°C condition. In order to determine the effects under short-term exposure, larvae of F. chinensis were exposed to 27 (ambient), 31 or 34°C only for one hour in the second experiment. The number of larvae settling for 24 h after the exposure and their survivorship over subsequent week was monitored in the ambient temperature condition. Larvae of F. chinensis exhibited greater settlement at higher temperature treatments and constantly low post-settlement mortalities (< ca. 17%) in all temperature treatments, resulting in the highest number of settled larvae at 34°C treatment. These results suggested two different effects of elevated temperature on the early stages of recruitment process of scleractinian corals; (1) the positive effect on larval settlement and (2) the negative effect on post-settlement survival under prolonged exposure.

Effects of elevated temperature on larval settlement and post-settlement survival in scleractinian corals, Acropora solitaryensis and Favites chinensis

Reproduction and recruitment in high-latitude coral populations in Japan have been little studied. A comprehensive study of the reproduction and early life history was conducted on nine common scleractinian coral species in Amakusa, southwestern Japan (32°N) from 2001 to 2003 including; (1) fecundity (the proportion of colonies with mature eggs), (2) timing and synchrony of spawning, (3) initial larval settlement pattern, (4) recruitment, (5) post-settlement mortality. The fecundity was high (76.7–100%) in six of seven species examined in 2002 and 2003. Annual spawning of the seven species occurred from mid July to August in 2001–2003, when seawater temperature was at the annual maximum. Spawning was highly synchronised among conspecific colonies and species in 2002 and 2003, with five species spawning five to nine nights after the full moon and another two spawning around the new moon. Temporal patterns of larval settlement of three spawning species during the first 10 days after spawning were similar to those of other spawning species from low latitudes. The number of scleractinian recruits on settlement plates, deployed from July to October (the major recruitment period at the study site), was low (2 recruits/m2) for the three consecutive years. Post-settlement mortality of 1–1.5 month old spat of five species ranged between 88 and 100% over 3–10 months in the field, similar to the values reported for both high and low latitude species (>94–99%). Among the key stages examined, the low recruitment rate may be the most important step in limiting successful reproduction and recruitment of these high-latitude scleractinian populations. The low recruitment rate may be attributable to (1) the reduced influx of larval supply from other coral populations, which are smaller and more isolated at high-latitudes and (2) the longer precompetent larval phase of broadcast-spawning corals which results in an increased chance of larvae being dispersed away from parent populations.

Reproduction and recruitment of scleractinian corals in a high-latitude coral community, Amakusa, southwestern Japan

Micro-crevice structure enhances coral spat survivorship

The scale and intensity of marine cage culture have increased in the Asian-Pacific region, particularly in oligotrophic waters where coral reef organisms flourish. In this study, the influence of marine cage culture on subtropical coral communities in turbid waters was evaluated by measuring environmental parameters and benthic community compositions at Magongwan in the Penghu Islands, Taiwan. A canonical discriminant analysis of environmental parameters revealed that elevated levels of ammonium, nitrite, and chlorophyll a (chl a) released from the cages were the main pollution indicators that, in addition to sedimentation and turbidity, distinguished Impact Zone 1 (cage-culture zone) from the other 2 zones - Impact Zone 2 (800 m away from the cages) and the reference zone - in these turbid waters. Results of the canonical correlation analysis indicated that the coverage extents of macroalgae, sponges, and zoanthids were strongly correlated with levels of ammonium, nitrite, phosphate, chl a, and dissolved oxygen. Coral communities in Impact Zone 1 were mostly composed of stress-tolerant massive and submassive corals, but were lacking branching Acropora corals. In contrast, coral communities in the other zones, with high habitat complexity and species richness, were dominated by coral species with diverse morphologies, including branching Acropora coral communities. These results suggest that marine cage culture has been causing chronic nutrient enrichment in the surrounding waters at Magongwan, which may have resulted in a deterioration of suitable habitats for coral reef organisms. Nevertheless, intermediate levels of nutrients and particulate organic matter relative to the other zones might have been caused by the adjacent cage culture, resulting in the high coral coverage and diversity in the Impact Zone 2 in particular.

/pdf/nutrient-enrichment-caused-by-marine-cage-culture-and-its-3wo1mvmr5j.pdf

Nutrient enrichment caused by marine cage culture and its influence on subtropical coral communities in turbid waters

This study examined the initial larval settlement pattern, the settlement-competency period, and the effect of temperature on settlement rates of larvae of the broadcast spawning reef coral, Platygyra daedalea, from the Great Barrier Reef. Approximately 19% of larvae attached to settlement substrata 3-4 days after spawning (DAS), prior to complete larval metamorphosis and permanent settlement, which began at 4-6 DAS. This early larval attachment behaviour could enhance the retention of some P. daedalea larvae on, or near, their natal reefs, thereby allowing some degree of self-seeding of local populations. In contrast, the maximum larval settlement-competency period was 93-105 DAS, with the peak period of larval settlement occurring at 36-42 DAS and 33-41 DAS in repeated experiments over two years. The delayed period of peak settlement and the extended competency periods of these larvae indicate that there is considerable potential for meso-scale and long-distance dispersal of some P. daedalea larvae. Slightly elevated temperatures enhanced the development and settlement rates of P. daedalea larvae, which suggests that seawater temperature may be an important factor influencing patterns of coral larval settlement on coral reefs.

http://www.coremap.or.id/downloads/ICRS9th-Nozawa_PH_9ICRS_Final.pdf

Larval settlement patterns, dispersal potential, and the effect of temperature on settlement of larvae of the reef coral, Platygyra daedalea, from the Great Barrier Reef

Yoko Nozawa

Papers

Effects of elevated temperature on larval settlement and post-settlement survival in scleractinian corals, Acropora solitaryensis and Favites chinensis

Reproduction and recruitment of scleractinian corals in a high-latitude coral community, Amakusa, southwestern Japan

Micro-crevice structure enhances coral spat survivorship

Nutrient enrichment caused by marine cage culture and its influence on subtropical coral communities in turbid waters

Larval settlement patterns, dispersal potential, and the effect of temperature on settlement of larvae of the reef coral, Platygyra daedalea, from the Great Barrier Reef