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Most studies have quantified coral recruitment using recruitment tiles temporarily deployed on reefs. However, the wide range of tile types used in different studies potentially influences recruitment patterns thereby hindering accurate comparisons among reef areas. We examined the effect of different tile types with different surface structure and composition on spatial (reef locations) and temporal (season) patterns of coral recruitment in the northwestern Philippines. Dead coral skeleton, terracotta, and fibre-cement tiles were deployed and retrieved quarterly over a 15-month period. In contrast to previous studies, patterns of standardized density and composition of recruits were consistent among tile types. Recruits varied spatially and were highest in Caniogan reef, followed by Cory reef and Lucero reef, suggesting that coral recruitment in the Bolinao-Anda Reef Complex (BARC) is influenced by reef location and existing coral cover. Highest recruitment was also found during the peak coral spawning season. The results of this study contrast with some previous reports which indicate that coral recruitment patterns are strongly influenced by recruitment substrate types. Our study suggests that once sufficient biological conditioning of the tile surfaces has occurred, the microbial and algal community present on the different tile surfaces are similarly conducive to larval settlement of some coral taxa. • Different tiles can be used as coral settlement and recruitment substrata and are appropriate for comparison between studies. • Standardized density and family of coral recruits recorded were similar across natura, fibre-cement, and terracotta tiles. • Different tile types that are biologically conditioned are similarly conducive to larval settlement of some coral taxa. • Recruitment patterns in BARC reefs are highly influenced by reef location and existing coral cover, and season. [ABSTRACT FROM AUTHOR]

Antipathella wollastoni is an antipatharian species common to Macaronesia, occurring in depths between 20 and 1425 m. Despite its importance as a habitat-forming species, there is no information about its basic biology. The aim of the current study is to describe its reproductive strategy, gametogenic cycle and reproductive timing. Sampling was performed monthly on six tagged colonies during one year and specimens were histologically processed. A. wollastoni was found to be a gonochoric broadcast spawner. Gametogenesis took place within the primary transversal mesenteries, and followed an annual cycle. The reproductive season coincided with an increase in seawater temperature but spawning, inferred from the disappearance of gametes, likely happened after the sea surface temperature peak of the year (September 2009). Polyp fecundity ranged from 1 to 309 oocytes/polyp. A decrease in polyp fecundity was detected in samples at the higher pre-spawning maturity stage, indicating possible repetitive spawning or oocyte absorption. Intra-colonial comparisons revealed a longer duration of the reproductive cycle in the medial colony section, and a gradient of increased oocyte size towards the apical section, possibly due to intra-colonial differences in energy allocation between reproduction and other biological processes, or as a strategy against predation on gametes/larvae. Colony height was positively correlated with polyp fecundity indicating that the reproductive output increases with colony size. [ABSTRACT FROM AUTHOR]

This study examined the reproduction of a cold-water coral, Primnoella chilensis (Philippi, 1894) from the Comau and Reñihué fjords in Chilean Patagonia. Samples were collected in September and November of 2012 and April, June, and September of 2013 from three sites within the two fjords. The sexuality, reproductive mode, spermatocyst stage, oocyte size, and fecundity were determined using histological techniques. This species is gonochoristic with one aberrant hermaphrodite identified in this study. Reproduction was found to be seasonal, with the initiation of oogenesis in September and suggested a broadcast spawning event between June and September. The maximum oocyte size was 752.96 µm, suggesting a lecithotrophic larvae. The maximum fecundity was 36 oocytes per polyp. Male individuals were only found in April and June. In June, all four spermatocyst stages were present. This suggests that spermatogenesis requires less time than oogenesis in P. chilensis . [ABSTRACT FROM AUTHOR]

Successful reproduction and larval dispersal are important for the persistence of marine invertebrate populations, and these early life history processes can be sensitive to marine pollution. Coal is emerging as a contaminant of interest due to the proximity of ports and shipping lanes to coral reefs. To assess the potential hazard of this contaminant, gametes, newly developed embryos, larvae and juveniles of the coral Acropora tenuis were exposed to a range of coal leachate, suspended coal, and coal smothering treatments. Fertilisation was the most sensitive reproductive process tested. Embryo survivorship decreased with increasing suspended coal concentrations and exposure duration, effects on larval settlement varied between treatments, while effects on juvenile survivorship were minimal. Leachate exposures had negligible effects on fertilisation and larval settlement. These results indicate that coral recruitment could be affected by spills that produce plumes of suspended coal particles which interact with gametes and embryos soon after spawning. [ABSTRACT FROM AUTHOR]

Despite all traditional conservation management efforts, coral reefs worldwide continue to face a future of degradation and destruction. Current studies call for the augmentation of coral reef management with restoration practices, particularly alternative reef management approaches, such as the ‘coral gardening’ tenet of active reef restoration. This includes the stock creation of sexually derived coral colonies and their mariculture in mid-water coral nurseries. In this study, single and aggregated (resulting in non-fusion and chimeric entities) spats of the branching coral Stylophora pistillata were studied. Planula larvae were settled and spat were reared ex situ for 50–75 days before they were transplanted to the in situ mid-water nursery in Eilat, Israel, where they were followed for up to two years, showing a very low (< 2%) detachment rate. Spats were cultured in horizontal and vertical orientations, in caged (for the first 9 nursery months) and noncaged scenarios, and on two nursery beddings (nets and ropes). Caging of horizontally situated young spats on the net substrate resulted in the highest survival (> 80% after 2 years). Corals farmed in a vertical orientation had the lowest survival rate of the caged experiments (36.7%) but showed that chimeric/aggregated entities performed significantly better than the single colonies. The uncaged experiments had low (32.7%) to zero surviving spats after two years in situ. The surviving colonies reared under the uncaged conditions were significantly smaller than the caged colonies after the 9 months in situ ‘caging period’. Generally, the placement of the young spats in the mid-water nursery resulted in high growth rates: After two years in situ, coral colony diameter increased from 0.1 cm to 8.16 ± 1.58 cm for the vertical caged scenario, and 7.08 ± 1.72 cm, 7.02 ± 1.48 cm for the two caged horizontal designs (HN and HR). This is nearly twice the growth rate observed in natal colonies. The midwater coral nursery is a much cheaper solution for growing corals compared to ex situ water tables, which require high maintenance and expensive facilities to mimic in situ conditions. Non-caged coral stocks showed reduced survival and growth rates, similar to previously published results. The culturing of caged spats in a horizontal position in a midwater nursery exponentially augment survival and growth rates, thus enhancing stock creation yields. This offers new possibilities for creating stocks of sexually derived spats from eco-engineering coral species such as S. pistillata . [ABSTRACT FROM AUTHOR]

Coral larvae released into the water column encounter different dissolved chemical cues secreted by organisms on the substratum that are engaged in spatial competition. These cues initiate vital biological processes in the larvae. In this study, the effects of crude extracts from the scleractinian corals Pocillopora damicornis and Porites cylindrica , and the soft coral Sarcophyton glaucum , on the survivorship, swimming behavior, and settlement of Pocillopora damicornis larvae were evaluated. High concentrations of heterospecific coral extracts caused a significant decline in both larval survivorship and settlement whereas conspecific extracts did not result in any larval mortality. Exposure to heterospecific extracts resulted in repulsion of larvae as indicated by a transient change in larval morphology and sustained swimming in the upper water column. In contrast, the conspecific extract enhanced larval exploration of both the water column and substratum and was able to induce larval settlement. These results suggest that chemical cues emanating from conspecifics and other coral species are capable of altering the biology of coral larvae, thus potentially influencing settlement behavior and species distribution on the reef. [ABSTRACT FROM AUTHOR]

Coral populations in the Persian Gulf have a reputation for being some of the toughest in the world yet little is known about the energetic constraints of living under temperature and salinity extremes. Energy allocation for sexual reproduction in Gulf corals was evaluated relative to conspecifics living under milder environmental conditions in the Oman Sea. Fecundity was depressed at Gulf sites in two Indo-Pacific merulinid species ( Cyphastrea microphthalma and Platygyra daedalea ) but not in a regionally endemic acroporid ( Acropora downingi ). Gulf populations of each species experienced high temperature bleaching at the onset of gametogenesis in the study but fecundity was only negatively impacted in P. daedalea and A. downingi . Large population sizes of C. microphthalma and P. daedalea in the Gulf are expected to buffer reductions on colony-level fecundity. However, depleted population sizes of A. downingi at some Gulf sites equate to low reef-wide fecundity and likely impede outcrossing success. [ABSTRACT FROM AUTHOR]

Dredging, river plumes and natural resuspension events can release sediments into the water column where they exert a range of effects on underlying communities. In this review we examine possible cause–effect pathways whereby light reduction, elevated suspended sediments and sediment deposition could affect the reproductive cycle and early life histories of corals. The majority of reported or likely effects (30 +) were negative, including a suite of previously unrecognized effects on gametes. The length of each phase of the life-cycle was also examined together with analysis of water quality conditions that can occur during a dredging project over equivalent durations, providing a range of environmentally relevant exposure scenarios for future testing. The review emphasizes the need to: (a) accurately quantify exposure conditions, (b) identify the mechanism of any effects in future studies, and (c) recognize the close interlinking of proximate factors which could confound interpretation of studies. [ABSTRACT FROM AUTHOR]

Coral reefs are an indispensible worldwide resource, accounting for billions of dollars in cultural, economic, and ecological services. An understanding of coral reproduction is essential to determining the effects of environmental stressors on coral reef ecosystems and their persistence into the future. Here, we describe the presence of and changes in steroidal hormones along with associated steroidogenic and steroid removal enzymes during the reproductive cycle of the brooding, pan-Pacific, hermaphroditic coral, Pocillopora damicornis . Detectable levels of 17β-estradiol, estrone, progesterone and testosterone were consistently detected over two consecutive lunar reproductive cycles in coral tissue. Intra-colony variation in steroid hormone levels ranged between 1.5- and 2.2-fold and were not statistically different. Activities of the steroidogenic enzymes 3β-hydroxysteroid dehydrogenase and cytochrome P450 (CYP) 17 dehydrogenase were detectable and did not fluctuate over the reproductive cycle. Aromatase-like activity was detected during the lunar reproductive cycle with no significant fluctuations. Activities of regeneration enzymes did not fluctuate over the lunar cycle; however, activity of the clearance enzyme UDP-glucuronosyl transferases increased significantly (ANOVA, post hoc p < 0.01) during the two weeks before and after peak larval release (planulation), suggesting that the activity of this enzyme family may be linked to the reproductive state of the coral. Sulfotransferase enzymes could not be detected. Our findings provide the first data defining normal physiological and lunar/reproductive variability in steroidal enzymes in a coral species with respect to their potential role in coral reproduction. [ABSTRACT FROM AUTHOR]

Population dynamics in marine sessile invertebrate communities are linked to both pre- and post-settlement processes. For species possessing low-dispersing, non feeding larvae, population demographics and distributions are primarily regulated by larval production and post-settlement effects. This study assessed the effect of temperature, photoperiod, rainfall and habitat on post-settlement mortality, growth, asexual reproduction (fission), larval production and recruitment in the abundant Great Barrier Reef brooding sponge Carteriospongia foliascens . The study was conducted over 24 months at two locations characterized by distinct hydrodynamics (wave height). Location-specific differences in growth, body size and fecundity for C. foliascens were attributed to water movement, with a higher wave height range corresponding to higher abundance of larger, more reproductive individuals. The positive effects of hydrodynamics on growth and larval production also translated to higher recruitment levels highlighting a stock-recruitment relationship in this species. C. foliascens showed no evidence of fission, and exhibited fluctuating growth trajectories in all size classes investigated. Decreasing growth variability corresponded with increasing size, reflecting growth trajectories for species having indeterminate growth. Results presented in this study highlight the importance of habitat characteristics for post-settlement processes, larval production and recruitment in low dispersing sessile invertebrate species, such as brooding sponges. [ABSTRACT FROM AUTHOR]

Abstract: Fragmentation has been regarded as the most important reproductive strategy in the threatened reef building coral Acropora cervicornis. Before the Caribbean-wide collapse experienced by A. cervicornis, asexual reproduction may have served as an effective source of new colonies to sustain and/or enhance local population growth. However, baseline information on the demographic success of fragments in nature is limited, hampering our ability to estimate the real contribution of asexual fragmentation to current population growth. In this study, natural occurring fragments of A. cervicornis were monitored for 18months at two sites in Puerto Rico in order to quantify their survival, growth, and branching dynamics. Fragment survivorship did not exceed 26%, growth rates were relatively low with mean values ranging between 0.0242±0.0168 (SE) and 0.0906±0.0301 (SE) cmd−1, and fragments barely produced new branches. No significant differences were found when comparing these demographic traits for different size categories. The relative low rates of survival, growth and branch production of natural fragments suggest that asexual fragmentation may not currently be a significant source of recruits for populations of this threatened coral. [Copyright &y& Elsevier]

Highlights: [•] Coral larval dispersal is modelled in the central Great Barrier Reef. [•] Graph theory tools are used to detect the presence of isolated reef clusters. [•] We identify important barriers to larval dispersal between clusters. [•] We find that dispersal distances may vary significantly in different clusters. [Copyright &y& Elsevier]

The logistics of research on deep-sea organisms imposes restrictions on studies that require repetitive long-term collections. Studies on the reproduction of deep-water corals have commonly been made without appropriate temporal series. This study included Madrepora oculata, Solenosmilia variabilis, Lophelia pertusa, and Enallopsammia rostrata, which are among the primary deep-sea reef building corals off Brazil. Samples were collected during 13 consecutive months by the Campos Basin Deep-Sea Corals Assessment Project (R&D Center of the Brazilian Energy Company, Petrobras) in Campos Basin (CB) off Rio de Janeiro State through a remotely-operated-vehicle at approximately 600 m depth. Of every monthly sampling campaign, an average of four to five colonies of all four species were investigated histologically. Colonies of both sexes were observed, indicating that all four species are gonochoric. For now, this appears to be the predominant reproductive pattern observed in corals in the area, as well as in deep-sea corals in general, where 80% of coral species are gonochoric. Although considered functionally gonochoric, M. oculata and L. pertusa presented a few colonies with different hermaphroditism patterns. E. rostrata and M. oculata presented continuous reproduction. Although fertile year-round, S. variabilis presents a reproductive peak between April and September (Autumn–Spring) in contrast with the seasonal reproduction recorded in the southwestern Pacific. L. pertusa had a seasonal reproductive peak, confirming previous observations of periodic reproduction in this species in the northeastern Atlantic. The possible spawning season of L. pertusa from CB concentrates between May and July (high frequency of mature gametes), while spawning occurs between January and March in the North Atlantic and between September and November in the Gulf of Mexico. Our results suggest that the studied species are broadcast spawners because no embryos or larvae were observed in any examined sample. This study, based on long-term sampling, provides the most complete data to date on the gametogenesis and temporal patterns of reproduction of four key deep-sea coral reef builder species. [ABSTRACT FROM AUTHOR]

The deep-sea solitary scleractinian, Fungiacyathus marenzelleri (Vaughan, 1906) is found at depths of 300–6328m, and is cosmopolitan in distribution. Previously this species had been examined from 2200m depth in the Northeast Atlantic and 4100m in the Northeast Pacific. This study examines gametogenesis and fecundity of this species from its shallowest occurrences worldwide, from ∼600m depth in the Southern Ocean. Samples were collected during three cruises to the Western Antarctic Peninsula during 2008 and processed for histological analysis. Similar to studies of other populations, F. marenzelleri in the Southern Ocean is gonochoric with gametes forming in clusters within the mesenteries. Samples numbers were low, but oocyte size-frequency patterns suggest irregular spawning (no larvae were detected) with no differences between the three months analyzed. Though fecundity (2837±121 per polyp) was similar to that seen in the NE Atlantic (2892±44.4 per polyp), oocyte sizes were much larger in this southern population. Maximum oocyte size was 1400μm (750μm NE Atlantic and NE Pacific), with previtellogenic oocytes reaching a size of around 300μm before undergoing vitellogenesis. This study demonstrates phylogenetically constrained reproductive mode across three oceans, with local environmental adaptations such as increased lipid loading during vitellogenesis, potentially enhancing cold-water survivorship by increased food availability in juvenile stages. [ABSTRACT FROM AUTHOR]

Abstract: The success of corals in tropical oligotrophic waters depends largely on their symbiotic relationship with the dinoflagellate algae residing in their tissues. Understanding the dynamics of this symbiosis is essential to predict how corals respond to environmental stressors, such as changes in nutrients availability, water temperatures and irradiance. This study presents a numerical model of the symbiotic relationship between a heterotrophic coral (cnidarian) host and autotrophic symbiotic dinoflagellates, including the major metabolic and physical functions of the system, under non-bleaching conditions. The coral acquires nitrogen (N) through two processes, uptake of dissolved inorganic nitrogen () and heterotrophic feeding (Z N). Numerical experiments were used to highlight the importance of these different sources of N for coral survival and growth. The model was analyzed for four external nutrient supply scenarios, using combinations of two rates (high and low) and two Z N rates (high and low), and for a range of light levels. The model outputs showed the importance of the algae symbionts to the coral host as a source of both N and C when the feeding rate was limited, with heterotrophic feeding providing only 14% of the N needed to sustain the host biomass for the low Z N +high scenario. In contrast, with no light or low light, conditions under which the symbiont population dies, the host was able to survive if Z N was high. Living inside the host the symbiont population thrived as long as there was enough light, as well as, DIN and DIC in the host tissues, independent of whether N was supplied as Z N or . Translocation and recycling of nutrient were two of the most important features of this model, emphasizing why it is essential to resolve host and symbiont in a coral model. The model highlights that the interchangeability of N sources, and the ability to exchange and recycle nutrients in the host-symbiont system, is the key to coral survival in nutrient poor environments. [Copyright &y& Elsevier]

Abstract: Knowledge of the reproductive life-history of deep-water corals is important for assessing their vulnerability to anthropogenic impacts. Yet, the reproductive biology of many deep-water corals, especially members of the subclass Octocorallia, has not been examined. We used histological techniques to describe the reproductive biology of the deep-water gorgonian coral Acanella arbuscula from the northwest Atlantic. All colonies examined were gonochoric, and no embryos or planula larvae were observed in the polyps. Mean polyp-level fecundity (females: 21.0±17.5 oocytes polyp−1, and males: 13.9±13.5 sperm sacs polyp−1) is high compared to other deep-water gorgonians, and polyps closer to the branch tips had the highest fecundities in both females and males. The presence of large oocytes (maximum diameter 717.8μm) suggests that A. arbuscula produces lecithotrophic larvae. Despite the potentially high fecundity and small size at first reproduction, the paucity of information on dispersal and recruitment, combined with its longevity, vulnerability to bottom fishing gear, and ecological role as a structure-forming species, still warrants the classification of A. arbuscula as a vulnerable marine ecosystem indicator. [Copyright &y& Elsevier]

Abstract: Phosphate contamination can negatively affect corals, modifying growth rates, skeletal density, reproduction, mortality, and zooxanthellae. We determined the effects of elevated phosphate on coral growth and density. Genetically distinct colonies of Acropora muricata were sub-divided and distributed among three 110-L aquaria, and exposed to phosphate levels of 0.09, 0.20, and 0.50mgL−1 for four months. Total skeletal length, living tissue length, weight, branch production, and polyp extension were measured. Linear extension and tissue growth increased under all conditions. Growth rates were highest at a phosphate concentration of 0.50mgL−1. Weight increased through time, graded from low to high with phosphate concentration. Density decreased through time, and was significantly lowest in the high phosphate treatment. Phosphate concentration produced no visible effects of stress on the corals, as indicated by polyp extension and lack of mortality. It is suggested that the phosphate enhanced growth was due to increased zooxanthellar populations and photosynthetic production within the coral. Skeletal density reduction may be due to phosphate binding at the calcifying surface and the creation of a porous and structurally weaker calcium carbonate/calcium phosphate skeleton. Increased phosphate concentrations, often characteristic of eutrophic conditions, caused increased coral growth but also a more brittle skeleton. The latter is likely more susceptible to breakage and damage from other destructive forces (e.g., bioerosion) and makes increased coral growth a poor indicator of reef health. [Copyright &y& Elsevier]

Abstract: The continuous worldwide degradation of coral reefs raises an urgent need for novel active restoration techniques as traditional conservation practices have failed to impede the incessant reefs'' decline. While applying the “gardening coral reefs” methodology in Eilat (Red Sea, Israel), we examined reproductive outputs of naturally-grown and outplanted, nursery-farmed Stylophora pistillata colonies from three coral-transplantation trials (November 2005, May 2007, and September 2008), along three reproductive seasons. Surprisingly, transplanted colonies showed better reproductive capacities than the natal Stylophora colonies during >4 post-transplantation years. A higher percentage of nursery-farmed colonies released planula larvae as compared to naturally-grown colonies. Gravid transplants also shed more planulae per colony, yielding significantly augmented numbers of total planulae over naturally developed S. pistillata colonies. Our results indicate that nursery-grown corals may be used to enhance reef resilience by contributing to the larval pool, forming an engineered larval dispersal instrument for reef rehabilitation. [Copyright &y& Elsevier]

Abstract: Recent research has shown that heterotrophic feeding has a strong effect on both maintenance and growth of corals by providing mainly a nutritional source of nitrogen and phosphorus. Nevertheless, no study has yet been undertaken on the interactions between feeding and sexual reproduction in corals. This study examines the effects of heterotrophic feeding on the sexual reproduction of Pocillopora verrucosa in aquaria. Rotifers were used as a live food source at two concentrations ((LFC=low feed colonies)=5×102 organismsl−1; (HFC=high feed colonies)=15×102 organismsl−1) with an unfed control (UC=unfed colonies). Three replicates of five colonies were used for each treatment. Rotifers were distributed among the nine aquaria four times per week for 3h. Histological sections of coral polyps were prepared to monitor the development of gametogenic stages and the fecundity of the colonies. The number and size of oocytes, sperm sacs and gonad stages were determined in each polyp. Both fed and starved colonies of P. verrucosa proved to be simultaneous hermaphrodites and broadcast spawners. The gametogenesis period was short (3months) and occurred from October to December 2007. No spawning event was observed in the aquaria. However, the disappearance of mature oocytes in samples collected in January 2008 suggested that spawning took place between December 2007 and January 2008. Heterotrophic feeding appeared to have a negative effect on reproduction in P. verrucosa. The results showed that both the proportion of polyps with gametes and the reproductive effort were lower in the fed than in starved colonies. It is likely that an energetic trade-off occurred between reproduction and other metabolic functions. However, oocytes were bigger in fed corals compared with the unfed controls. Several hypotheses are proposed to explain these metabolic/energy distribution patterns. [ABSTRACT FROM AUTHOR]

Abstract: The objective was to examine the effects of cryoprotectants on oocytes of hard corals (Echinopora spp.) to obtain basic knowledge for cryopreservation procedures. Oocytes were exposed to various concentrations of cryoprotectants (0.25 to 5.0M) for 20min at room temperature (25°C). Two tests were used to assess ovarian follicle viability: fluorescein diacetate (FDA)+propidium iodide (PI) staining, and adenosine triphosphate (ATP) assay. Both FDA+PI staining and ATP assay indicated that cryoprotectant toxicity to oocytes increased in the order methanol, dimethyl sulfoxide (DMSO), propylene glycol (PG), and ethylene glycol (EG). The no observed effect concentrations for Echinopora spp. oocytes were 1.0, 0.5, 0.25, and 0.25M for methanol, DMSO, PG, and EG, respectively, when assessed with FDA+PI. The ATP assay was more sensitive than FDA+PI staining (P<0.05). Oocyte viability after 1.0M methanol, DMSO, EG, or PG treatment for 20min at room temperature assessed with FDA+PI tests and ATP assay were 88.9±3.1% and 72.2±4.4%, 66.2±5.0% and 23.2±4.9%, 58.9±5.4% and 1.1±0.7%, and 49.1±5.1% and 0.9±0.5%, respectively. We inferred that the ATP assay was a valuable measure of cellular injury after cryoprotectant incubation. The results of this study provided a basis for development of protocols to cryopreserve coral oocytes. [Copyright &y& Elsevier]

Abstract: The larval development of three species of deep-water scleractinian, Flabellum thouarsii, F. curvatum and F. impensum, was examined from samples collected from the deep continental shelf off the Western Antarctic Peninsula between 1999 and 2001. All three of these species were gonochoric, with females brooding multiple stages of planulae larvae. Mean fecundity was found to be high (F. thouarsii, 2412 oocytes per polyp (opp) (±1554sd); F. curvatum 1618opp (±1071sd); F. impensum, 1270opp (±884sd)). F. thouarsii has a previtellogenic oocyte size of ∼500μm and a maximum oocyte size of ∼4800μm. F. curvatum has a previtellogenic oocyte size of ∼800μm and a maximum oocytes size of ∼5120μm, and F. impensum has the largest oocyte sizes with a previtellogenic oocyte size of ∼1000μm and a maximum oocyte size of ∼5200μm. Larvae were found free within the gastrovascular cavity and embedded within the mesenterial gastrodermis. Three tentative stages of larvae were observed within female individuals, with the final stages having prominent tentacle buds and oral areas. A maximum of two larvae were found per mesentery in F. thouarsii and F. impensum, and four larvae were found per mesentery for F. curvatum. Four stages of spermatogenesis also were observed using histological techniques. The observations are discussed in relation to modes of reproduction in Antarctic waters and the deep sea. [Copyright &y& Elsevier]

Abstract: In coral aquaculture, sexual reproduction increasingly plays an important role for serving trade and reef restoration purposes. However, until coral juveniles reach a semi-stable size which makes them less vulnerable against algal growth and sedimentation, high mortality rates may occur in the first several weeks to months after settlement. In the present study, the influence of several food sources on the growth and survival of newly settled primary polyps was studied under laboratory conditions for 5 months. In order to estimate effects on specimens of both reproductive modes, experiments were carried out with the brooder, Favia fragum, and with the broadcast spawner, Acropora tenuis. Primary polyps kept in 2-liter aquaria were daily fed with freshly hatched Artemia salina, the micro algae Phaeodactylum tricornutum and a commercially available dry food (Nori Micro, Zoolife®), respectively, at various concentrations. Growth rates in both species were significantly higher in the Artemia treatment with maximum rates of 9.4±4.9 mm2 (mean±S.D.; d =5 months) for F. fragum and 26.8±10.3 mm2 (d =5 months) for A. tenuis compared to all other treatments and the control (no additional food). Survival in F. fragum was overall higher than 60% in all treatments with maximum rates of 85.0±12.6% at the highest Artemia concentration. Survival rates in A. tenuis ranged from 28.9±4.7% (lowest Nori concentration) to 86.2±5.9% (medium Artemia concentration). The present study shows that Artemia nauplii may greatly enhance the growth and partly enhance the survival of early sexual recruits which may significantly help to more rapidly overcome the early and most fragile post-settlement stages. As a consequence, the residence time for sexual coral recruits in cost- and labour-intensive hatcheries may be greatly reduced. [Copyright &y& Elsevier]

Abstract: The effects of enhanced ultraviolet radiation (280–400 nm: UVR) on the fecundity of Acropora cervicornis were measured in field-transplanted colonies from 20 m to 1 m depth and vice versa at La Parguera, Puerto Rico. Fecundity was estimated from histological sections made from tissue samples obtained at different time intervals during the experimental period (March – August 2003). All colonies transplanted from 20 m to 1 m showed a 100% reduction in gonads per mesentery per polyp one month after transplantation, while those transplanted from 1 m to 20 m did not show any significant reduction in fecundity throughout the experimental period. The latter colonies did show however, a delay in the spawning times by releasing their gamete bundles approximately two-three weeks after the controls at 1 m and two months after the controls at 20 m suggesting an induced response as a consequence of changes in their daily light cycle due to less radiation (PAR and UVR) available at 20 m compared to 1 m. Control colonies at 20 m spawned after the full moon of June 2003, while the controls at 1 m spawned 5–6 days after the full moon of July 2003. While a possible reabsorption of the gametes occurred in A. cervicornis colonies transplanted from 20 m to 1 m, the expulsion of these gametes due to the sudden stress caused by the transplantation is not discarded. The results suggest that sudden increases in UVR can completely stop sexual reproduction in ramose broadcasting coral species, which in turn can affect the dominance of the species and the composition and structure of shallow reef environments. [Copyright &y& Elsevier]

Most broadcast spawner corals have a vitellogenic phase that lasts at least 6 months. It is established that estrogen regulates vitellogenin synthesis in vertebrates. Although some research have been conducted on the physiological role of sex steroids in corals, little is known about their involvement in oocyte development. This study aimed to detect steroid hormones – progesterone, testosterone, and estradiol-17β (E2) – in Acropora tenuis and study the relationships between vitellogenesis/vitellogenin synthesis and these steroids. This study also investigated the effect of E2 on vitellogenin synthesis in corals and identified steroidogenic enzymes in A. tenuis genome. Branches from tagged coral colonies were collected monthly from March to November. Histological observations showed that oocytes were vitellogenic from March to May (Stage IV and V), but not in June, and that gonads were occupied by immature oocytes in September (Stage I). Real-time qPCR revealed that vitellogenin (vg1 and vg2) transcript levels in coral branches were high in April and May, implying that corals actively underwent vitellogenesis during these months, and spawned before June. Liquid chromatography-mass spectrometry revealed that E2 could be detected in coral branches in March, April, and May, but not in June, whereas testosterone and progesterone did not fluctuate much in the same months. Immersing branches in E2–containing seawater failed to increase vitellogenin transcript levels. The results indicate that E2 is involved in oogenesis but does not positively regulate vitellogenin synthesis. Steroidogenic enzymes (except CYP19A) were identified in A. tenuis , suggesting that corals may endogenously synthesize progestogens and androgens from cholesterol. [Display omitted] • Three major vertebrate steroid hormones were detected in the scleractinian coral, A. tenuis. • Monthly histological, molecular, and steroid analysis showed a relationship between the presence of E2 and oogenesis. • E2 immersion experiment showed no significant changes in mRNA expression of vitellogenins. • E2 might not be related to vitellogenin synthesis in corals. [ABSTRACT FROM AUTHOR]

Fertilization is a critical life history event and important to population dynamics. Successful fertilization relies on encounters of compatible and viable sperm and eggs. Scleractinian corals that spawn their gametes directly into the water column may experience limitations from sperm dilution and delays in initial sperm-egg encounters that can impact successful fertilization. Notably, the same issues can be experienced when conducting ex situ larval culture. Therefore, experiments were completed using spawned eggs and sperm of the reef corals Acropora tenuis , A. millepora and Favites colemani to determine the optimal ranges of sperm concentrations (<103 to 107 mL−1) and temporal response patterns when crossing of eggs and sperm was delayed (30 min to 10 h). The results showed that sperm concentrations below 103 mL−1 yielded low rates of fertilization for all three species (<30%), but that sperm concentrations at 104 mL−1 resulted in higher rates of fertilization for the Acropora spp. (>65%) and > 90% fertilization rates for F. colemani. Sperm concentrations of 105–107 mL−1 resulted in the highest observed fertilization rates for all three species (>90%). High fertilization rates (>80%) occurred when eggs and sperm were combined after 30 min and up to 2 h after spawning for F. colemani and up to 4 h for A. tenuis and A. millepora gametes. Fertilization rates were significantly reduced (<30%) after a delay of 4 h for F. colemani and after 6 h for the two Acropora species. No fertilization occurred after a 10-h delay in combining gametes for all the tested coral species. Therefore, optimal fertilization success for these coral species rely on sperm densities of ≥104–106 mL−1 and gametes should be combined within two hours after spawning for optimising larval culture. • Fertilization success varies among coral species. • Maximum fertilization can be achieved with concentrations of sperm >104 mL−1. • Combining gametes within the first few hours can result in highest rates of fertilization. • Reduced fertilization success was related to a decreased percentage of viable eggs. [ABSTRACT FROM AUTHOR]