Search

Hard-shell-mating is the typical way that semi-terrestrial and terrestrial crabs copulate, when females reproduce with a hard carapace during the intermoult period and the couples have a brief or absent pre- and post-copulatory behaviour. For Gecarcinidae crabs there are few studies on reproductive behaviour, and are especially rare for isolated species, as in the genus Johngarthia. Here, we describe the mating behaviour of the endangered insular crab J. lagostoma endemic of the South Atlantic Ocean, with a focus on pre-, copulatory, and post-copulatory behaviours. Observations were made on 20 pairs in the field, with every female in intermoult. Accessory behaviours were absent, with copulation beginning after sexual recognition. After mating, there were no records of males guarding or embracing females. All couples had the female in an upper position and passive males, which do not react when other males are near the mating site. The size of the chelipeds and males were random and not determinant to mating. However, yellow crabs predominated (95%) in mating pairs and the linkage of colouration to sexual selection needs to be more elucidated because purple crabs are less frequent in the population and the lower representation in the couples can be an effect of this. Experimental studies are required to investigate sexual selection and the occurrence of the behaviour described herein at other locations. [ABSTRACT FROM AUTHOR]

Egg size and fecundity are often used as proxies for coral reproductive success and health. The amount of energy a coral invests in reproduction reflects its environmental conditions during gametogenesis. Additionally, assuming resources for reproduction are limited, it is thought that an increase in egg size should result in a decrease in the number of eggs produced i.e. investing in many small eggs or fewer larger eggs. The biannually spawning populations of Scott Reef offer a unique opportunity to compare the egg size and polyp fecundity of corals exposed to different environmental conditions during gametogenesis, prior to spawning in autumn (March) and spring (October). In this study, we investigated the relationship between egg size and polyp fecundity within and between seven Acropora species from 2008 to 2010. We also quantified the fecundity and egg size of four Acropora species that spawn during both autumn and spring (2008–2010). We found no seasonal variability in egg size and fecundity in the species studied here, possibly as a result of a summer light regime being impacted by high cloud cover in cyclone season. There was high natural variability and no apparent trade-off between egg size and fecundity, both within and between each species. These findings challenge the assumption that egg size and fecundity are negatively correlated, or that a simple, energetically constrained trade-off exists between the two. [ABSTRACT FROM AUTHOR]

Early life history traits of brooding corals are often affected by the environmental conditions experienced by parental colonies. Such parental effects can impact offspring survival, which influences the overall success of a population as well as resilience to environmental challenges. This study examines the reproductive ecology and early life history traits of the brooding coral Porites astreoides across a depth gradient in Bermuda. Fecundity, larval size, larval Symbiodinium density, and settlement success, as well as post-metamorphic juvenile survival, growth, and Symbiodinium density were compared across three reef sites representing an inshore patch reef (2-5 m), an offshore rim reef (8-10 m), and an upper-mesophotic reef (30-33 m). Although fecundity did not differ across sites, larvae produced by colonies on the patch reef site were smaller, had lower Symbiodinium densities, and had lower rates of settlement and juvenile survival compared to larvae from colonies on the rim and upper-mesophotic reef sites. Larvae produced by colonies from the rim and upper-mesophotic sites did not differ in size or Symbiodinium densities; however, rates of settlement, growth, and survival were higher for larvae from the upper-mesophotic site compared to those from the rim reef site. These results indicate that offspring quality and success vary among sites with differing environmental conditions and may imply higher recruitment potential and resilience for upper-mesophotic corals. [ABSTRACT FROM AUTHOR]

Knowing the gametic development of the coralPocillopora damicornisand its relationship to environmental variation at La Azufrada reef (2°58′10″N and 78°11′05″W, Gorgona Island, Colombian Pacific Ocean) is essential to understanding the capacity for sexual replenishment of this population. Due to the lack of information about its sexual reproductive process, we collected tissue samples of healthy and unhealthy colonies (with bleaching, or algal or cyanobacterial overgrowth), along with salinity and sea-surface temperature data, between October 2010 and October 2011. During histological analysis we observed four oocyte and three spermary developmental stages in healthy colonies. Colonies were hermaphrodites with synchronous gonadal maturation in May 2011. However, polyps within colonies were either gonochoric, with a 7.8 ± 11.8:1 (mean ± SD) female to male polyp sex ratio, or hermaphroditic, with a 2.8 ± 1.5:1 (mean ± SD) oocyte to spermary ratio. The low number of spermaries observed may reduce the chance of effective fertilization and could explain the low sexual recruitment observed in the study area. There was a positive correlation between salinity and the mean number of gametes (oocytes and spermaries) produced per polyp, although both oocytes and spermaries increased during the warm water, high-salinity season (March to July 2011). Colonies with bleaching or overgrowth by cyanobacteria or algae had no gametes, suggesting that population recovery after disturbances might not be effective if it depends solely on sexual reproduction. [ABSTRACT FROM PUBLISHER]

This study examined the effects of colony size and polyp position on six variables of polyp fecundity [egg number, egg size, total egg volume, total testis volume, total gonad volume, and gonad ratio (egg volume/testis volume)] in three tabular Acropora corals (Scleractinia), A. hyacinthus, A. japonica, and A. solitaryensis. Samples were collected from various colony sizes ( n = 21-30 colonies species), just before the predicted spawning at Kochi, Japan, in 2009. Five replicate polyps were sampled at three positions (center, middle, and outer) from the center to the marginal area in each tabular colony. Results indicated effects of colony size and polyp position on both male and female gonads polyp. A positive effect of colony size was observed on variables of female gonads polyp (egg number, total egg volume) in A. hyacinthus only, while the positive effect on the variable of male gonads polyp (total testis volume) was common in all Acropora species, with total testis volume polyp increasing 2-4-fold from the small (200-400 cm) to the large size class (5,000-9,000 cm). Among the polyp positions, lower values were observed mostly in center polyps in A. hyacinthus, while lower values were observed only in outer polyps in the other Acropora species. The distinct patterns between A. hyacinthus and the other two Acropora species suggest different reproductive strategies at the species level. Further studies are needed to confirm the prevalence of these effects in scleractinian corals, which will broaden our understanding of reproductive life history strategies and improve the estimation of reproductive performance. [ABSTRACT FROM AUTHOR]

The recent intensification of human disturbances in the Caribbean has increased the prevalence of partial mortality on coral colonies. Partial mortality can change colony size by directly shrinking colonies or by splitting colonies into fragments. A reduction in colony size can also adversely affect fecundity and fitness as internal resources shift away from reproduction toward colony maintenance. This study aimed to determine whether three Caribbean coral species, Siderastrea siderea, Montastraea faveolata, and Diploria strigosa, along the reef tract in Puerto Morelos, Mexico (2052′N, 8651′W), continued to dedicate resources to reproduction when colonies were fragmented to pre-maturation size. Contrary to expectations, eggs were found in colonies that were smaller than the maturation size and had been subjected to partial mortality. The continued dedication of resources toward reproduction, even in the smallest colonies, suggests that resource trade-offs away from reproduction are not as rigid as previously suggested in stressed corals. [ABSTRACT FROM AUTHOR]

The sexual system in corals refers to the spatial and temporal pattern of sexual function within an individual coral polyp, colony or population. Although information on sexual systems now exists for over 400 scleractinian species, data are still lacking for some important reef-building taxa. The vast majority of scleractinians are either simultaneous hermaphrodites or gonochoric with other sexual systems rarely occurring. Diploastrea heliopora is one of the most ubiquitous and easily recognised reef-building species in the Indo-West Pacific; however, surprisingly little is known about its reproductive biology. The aim of the present study was to examine the reproductive biology of D. heliopora colonies on chronically impacted, equatorial reefs south of Singapore. Here we show that in Singapore, D. heliopora is a broadcast spawner with predominantly gonochoric polyps. Colonies, however, contained male, female and a low proportion of cosexual polyps during the 14-month sampling period. The most plausible explanation for this is that polyps switch sexes with oogenic and spermatogenic cycles occasionally overlapping. This leads to colony level alternation of sex function within and between breeding seasons. While this sexual system is atypical for scleractinians, it supports molecular evidence that D. heliopora is phylogenetically distinct from species formerly in the family Faviidae. [ABSTRACT FROM AUTHOR]

Most coral species off Australia's west coast spawn in the austral autumn (March-April), with a few species also spawning in the southern spring or early summer (November-December). This is the reverse timing to spawning recorded off Australia's east coast. Porites lutea, a gonochoric broadcast spawner that is common on Australia's west coast, is shown here to spawn in the months of November or December, as it does on Australia's east coast. Spawning occurred between 2 and 5 nights after full moon, with the majority of spawning activity on night 3. Gametes developed over three to four months with rapid development in the last two weeks before spawning. Zooxanthellae were typically observed in mature oocytes, only a week before spawning so their presence may provide a useful indicator of imminent spawning. [ABSTRACT FROM AUTHOR]

The annual gonad development of a shallow (20 m depth) population of the Mediterranean gorgonian Eunicella singularis was found to be closely synchronized with that of a deep (60 m depth) population, but differences were observed in the gonadal output, with the shallow population producing more and larger sexual products. Lipid content in the shallow population showed a marked seasonality, peaking during summer. In contrast, lipid content remained persistently lower in the deep population. Fatty acids as well as C/N composition were also seasonal in the shallow population and more constant in the deep one. The isotopic composition (δN and δC) of the shallow colonies was similar to values observed for passive suspension feeders with symbiotic algae, whereas the deep colonies exhibited values similar to those of aposymbiotic passive suspension feeders that primarily feed on microzooplankton and particulate organic matter. These results highlight the importance of considering the depth-related variability among populations in order to achieve a better understanding of the ecology of sessile benthic suspension feeders. [ABSTRACT FROM AUTHOR]

The genotypic compositions of two populations of the brooding coral, Pocillopora damicornis, were studied by exhaustive sampling of adult colonies on a fine scale in southern Taiwan. In addition, 100 larvae were randomly selected among more than 1,000 brooded larvae collected from a single broodparent within each population. Using 7 polymorphic microsatellite markers, both populations were found to be highly clonal, and 7 clonal lineages were characterized. One clonal lineage (C1) dominated both study areas and comprises 54.9% of all colonies sampled, while any of the other 6 clonal lineages represented no more than 5%. Among the 100 larvae randomly selected for genotyping from each broodparent, the extent of clonal reproduction was high, and only 29 and 6 larvae, respectively, were found to be genotypically different from their broodparent. Among the 35 genotypically distinct larvae, 33 were thought to be derived from sexual reproduction, and 2 were assumed to be clonal propagules that had undergone somatic mutations. Two genotypically identical larvae were also found in one of the 2 sexually derived larva arrays, indicating the possible existence of polyembryony. The high proportions of clonality in both adult colonies and brooded larvae suggest that asexually produced larvae might significantly contribute to the recruitment of local populations. The dense clonal population of P. damicornis in the study area favors the quick recolonization view of clonal propagules after disturbances. [ABSTRACT FROM AUTHOR]

The increasing decline of Caribbean reef-building species underlines the importance of more information on their reproductive biology and ecology. This study compares the reproductive biology of the three species of Diploria, an important Caribbean reef-building genus affected by bleaching and disease, by: (a) characterizing their gametogenetic cycles simultaneously, (b) exploring the spatial and temporal variability in reproductive traits within and across species, (c) assessing fecundity and the minimum size of sexual reproduction, and (d) comparing information with other studies in the Caribbean. Starting in 1999, one tissue core was collected every month (for 17 months) from each of at least five large, tagged colonies of each species in La Parguera, Puerto Rico. Three more temporally spaced samplings were done during summer of 2000 and winter–spring of 2001 and 2002. Tissues were fixed in Helly’s solution, rinsed in fresh water, decalcified with 10% HCl, and preserved in 70% ethanol, embedded in paraplast, cut, and thin slides (7 μm) prepared and stained with Heidenhain’s Aniline-Blue method. Maximum egg size, number of eggs and spermaries were measured and gametogenetic cycles assessed. Microscopic observations confirmed that all three species were simultaneous hermaphrodites with a single, annual gametogenetic cycle. Spermatocytes and oocytes developed within the same mesentery but were not intermingled. Female gametes developed several months earlier than that of males, but both reached maturation simultaneously. Minor differences in the onset of gametogenesis were found for D. strigosa and D. clivosa, with both spawning after 10 p.m. between 8 and 10 days after the August and/or September full moons. D. labyrinthiformis on the other hand, began oogenesis in early July and spawned after 11 p.m. between 7 and 10 days after the April and/or May full moons. Spatial and temporal variability in mean number of spermaries and eggs/mesentery among colonies within and among species were found. D. labyrinthiformis had consistently significant higher mesenterial and polyp fecundity compared to the other two species over the 3 years. Average egg diameter varied between 240 and 246 μm and was similar among the three species. D. strigosa and D. clivosa sexual reproductive characteristics were similar to those of other large broadcast spawning Faviidae (i.e. Montastraea spp) in the region. In contrast, D. labyrinthiformis was a spring spawner (similar to Colpophyllia natans in Puerto Rico), which together with its significantly different micromorphology suggests that it might be phylogenetically more distant to the other taxa. [ABSTRACT FROM AUTHOR]

Paramuricea clavata (Risso, 1826) and Eunicella singularis (Esper, 1794) are the most representative gorgonian species in hard bottoms sublittoral communities in the Western Mediterranean Sea. Reproductive cycles of two populations of both species were studied in two distinct locations approximately 600 km apart (Medes Islands and Cape of Palos), in order to assess interpopulation variability on a relevant geographic scale. Seasonal variation of lipid concentration levels in the gorgonian tissue was used as a tool to quantify energy storage by each studied population in order to explain possible interpopulation differences in gonadal output. Sex ratio in Medes Islands populations of both species was 1:1, while in Cape of Palos sex ratio was significantly male biased (1:7) in P. clavata, and female biased (1.7:1) in E. singularis populations. Spawning timing occurred in all cases coinciding with a marked increase in sea-water temperature in spring, and after the most successful feeding season, but comparing localities there was a clear temporal shift in the time of gametes release, appearing well linked to the shift in sea-water temperature rising in spring in both sites at the depth where populations are placed. Therefore, in this study the temperature appears as the main synchronizing factor of gonadal development within these populations. Significant differences in gonadal volume per polyp were found in both species owing mainly to differences in the number of gonads per polyp between populations, with Cape of Palos populations displaying higher values in both studied species, suggesting that the exposition to different local conditions may be reverted in a different gonadal output. But the observed patterns in lipid concentrations levels in gorgonians disable us to conclude that lipid concentration levels explain the observed differences in gonadal output found in this study. [ABSTRACT FROM AUTHOR]

The reproductive patterns of four Antarctic gorgonian species have been investigated. Two of them, Dasystenella acanthina and Thouarella sp., present the bottle-brush-shape type; the other two, Fannyella rossii and Fannyella spinosa, are fan-shaped. Two different reproductive patterns have been observed in D. acanthina and Thouarella sp., which point to two size classes in the frequency distribution of oocytes. This feature indicates a reproduction cycle with overlapping generations, being each of them of more than one year, probably with seasonal spawning. F. rossii and F. spinosa show only one size class of oocytes, which could point towards an annual reproductive cycle. The presence of larvae in the gastrovascular cavities in both Fanyella species and Thoaurella sp. is a sign of a possible larvae release during austral summer. The number of oocytes per polyp ranges from 1.1 ± 0.10 SE to 1.5 ± 0.06 SE, and the size ranges from 50 to 1200 μm. The number of spermatic cysts ranges from 2.6 ± 0.19 SE to 5.0 ± 0.21SE, and their sizes range from 50 to 800 μm. These values are comparable to the reproductive trends and features found in gorgonians from other latitudes, which correspond in some cases with similar morphotypes. These coincident strategies could be related to morphological similarities rather than with latitude or water temperature. The results of this study indicate that octocoral morphology may play a crucial role in determining the reproductive output of these organisms. [ABSTRACT FROM AUTHOR]

Colonial epifauna are vulnerable to the effects of bottom fishing, but impacts on the life histories of these non-target animals have not been examined extensively. Dredging potentially impairs sexual reproduction by invoking regeneration and induces clonality by severing colonies or through the abortion of damaged modules. This study investigated the potential for commercial-scale scallop dredging to alter sexual and asexual (“clonal”) reproduction in the hydroidSertularia cupressina. In total, 1,071 colonies from 104 epizoic microhabitats (upper valves of live scallops relatively undisturbed by fishing) and 75 epilithic microhabitats (cobbles more severely disturbed by fishing) were collected from 53 to 94-m depths in the Bay of Fundy (Atlantic Canada). Colony abundance, injury frequency (proportion of colonies with sealed, snapped off stems), percentage of fertile colonies and sexual fecundity (number of gonophores and gonophore dimensions) were measured on all substrata. Ten randomly amplified polymorphic DNA (RAPD) primers were used to estimate clonal diversity. Field experiments found no significant effect of microhabitat differences between scallop and cobble substrata on fecundity and clonality inS. cupressina, while experimentally-induced injuries suppressed the percent of fertile colonies. On the fishing grounds, colonies on scallop valves were more abundant and sexually fertile than their counterparts on cobble, and all were sexually derived. In contrast, colonies on cobbles had a greater percentage of injury, were less fertile and were frequently clonally-derived. Impacts of fishing-related injuries on reproduction in colonial epifauna have been overlooked, yet the long-term consequences of such impacts could result in reduced adaptability, recruitment and recovery potential of these and dependent organisms. [ABSTRACT FROM AUTHOR]

Broadcast spawning of gametes with planktonic development of larvae is the most common reproductive mode in tropical corals, and is generally thought to optimize the dispersal potential of larvae. To this end, many previous studies of coral larval dispersal have focused on the maximum time larvae can remain competent to settle and consequently how far they might disperse. However, dispersal ability of broadcast-spawned coral larvae will be linked, at least in part, to the minimum time to settlement competency as well as the length of the planktonic period—although estimates of minimum time to competency remain largely anecdotal, with few rigorous studies of the pre-competent period. To determine the minimum time to larval settlement in two species of broadcast-spawning coral ( Platygyra daedalea and Goniastrea favulus), we monitored larval settlement rates in aquaria every 6 h from the time larvae commenced swimming (i.e. were ciliated, fully developed larvae) for a period of approximately 10 days. For P. daedalea, peak settlement occurred between 60 and 66 h following fertilization (2.5 and 2.75 days), which is markedly earlier than the 4- to 6-day time period commonly cited as the minimum time before broadcast-spawned coral larvae are competent to settle. Surprisingly, it was also clear from our experimental results that settlement in P. daedalea occurred as a distinct pulse during the 60- to 66-h period, rather than continuously throughout the study period. G. favulus larvae also appear to be able to settle quickly (from 54 h following fertilization). We argue, on the basis of these short competency times and apparently rapid settlement, that dispersal in broadcast-spawning coral larvae may not be as great as has previously been assumed. [ABSTRACT FROM AUTHOR]

Photosynthetic, growth, and reproductive characters for colonies of the massive coral Montastraea faveolata were measured at 3-m-depth and 18-m-depth populations in the Florida Keys in 1993 to investigate reproductive behavior across depth. I tested the hypothesis that reproductive traits would exhibit depth-related decreases similar to those documented for photosynthetically derived energy availability and growth rate. Colonies at the 18 m site had significantly reduced access to photosynthetically derived energy compared to colonies at 3 m depth. Linear skeletal extension rates were also reduced at the deep site (mean±SE; 3 m: 6.13 mm year-1±0.35; 18 m: 3.44 mm year-1±0.36; P<0.001). Contrary to expectations, depth did not affect most reproductive characters. Reproductive allocation, the amount of lipid invested in reproduction, was similar between depths (3 m: 3.74 mg lipid cm-2±0.55; 18 m: 3.88 mg lipid cm-2±0.62; P<0.8). Reproductive effort, the proportion of total lipid invested in reproduction, was also similar between sites (3 m: 41.4%±4.7; 18 m: 47.3%±7.12; P<0.163). Colonies within a depth did differ significantly in many gametic characteristics including eggs per gonad, total egg area, spermary area, total gonad area, and male allocation (the proportion of total gonad area invested in spermary tissue), but only total egg area differed between depths, and this was greater at 18 m (3 m: 55.63 μm2×104±4.76; 18 m: 60.51 μm2×104±3.41; P<0.035). Colonies at the two sites had similar polyp fecundity (egg production per polyp); however, a difference in polyp density between sites (3 m: 5.56 polyps cm-2±0.21; 18 m: 4.87 polyps cm-2±0.15; P<0.028) resulted in a significant reduction in area fecundity (egg production per square centimeter) at the 18 m site (3 m: 554 eggs cm-2±27.9; 18 m: 422 eggs cm-2±31.0; P<0.045). Thus, there was a depth-related fecundity cost arising from a change in colony architecture (i.e. polyp spacing) rather than a direct effect of depth on the number of eggs produced per polyp. Egg production per gonad was positively correlated between 1993 and 1994 (r=0.540, P<0.05), indicating that other reproductive characteristics may also be stable between years. [ABSTRACT FROM AUTHOR]

Examines the sexual reproduction of Brazilian coral Mussismilia hispida. Amount of vitelline material and peripheral germ vesicle; Pattern of sexual reproduction in scleractinian corals; Presence of brooded larvae in the solitary Scolymia wellsi.

Focuses on the fragmentation of colonies of the branching coral Pocillopora damicornis to determine the number and size of planula larvae released during one lunar reproductive cycle. Total number of planulae released per coral colony; Factors causing repeated breakage of corals.

Focuses on the study of sexual reproduction in the azooxanthellate octocoral Dendronephthya hemprichi Klunzinger. When the study began; Where was it studied; Information on D. hemprichi; Features of the gonads; Observation of gamete released; Reproductive features of D. hemprichi.