Migration,habitat use,and competition among mobile corals (Scleractinia: Fungiidae) in the Gulf of Eilat,Red Sea

We examined the impact of seven species of mobile mushroom corals (Fungiidae) on the community structure of sheltered reef slopes in terms of their patterns of migration, habitat use and competition with other benthic organisms. On fringing reefs at Eilat, Red Sea, polyps detached at 1 to 6 cm length, and grew to 11–55 cm length. Attached mushroom corals were oriented vertically in reef cavities. Detached corals migrated downward on the reef slope and onto rubble or soft substratum at the reef base, at 29 to 71 cmyr^–1. Mobility decreased with corallum size and extent of undersurface ornamentation. In aquaria, small corals righted themselves and migrated up to 6 cm d^–1 by nocturnally inflating and pushing their tissues against the substratum. Autonomous coral behavior and storm-generated water motion appeared to account for most fungiid mobility at Eilat. Mushroom corals did not damage each other upon contact, even in multi-species aggregations, but unilaterally damaged non-fungiid scleractinian corals. Their dominance during contact interactions retards overgrowth by larger attached scleractinians, and mobility allows them to colonize soft substrata not accessible to most other reef corals.     

Gas-liquid chromatograms of sesquiterpenes as finger prints for soft-coral identification

A possible additional means for aiding in the identification of soft corals based on their sesquiterpene composition, as determined by gas-liquid chromatography (GLC), is discussed. The use of this method for several species of Sinularia and Sarcophyton is illustrated. Several sesquiterpenes were identified, some of them for the first time from marine origin. Preliminary tests indicate that the sesquiterpene composition in the tested soft corals remained quite constant during different seasons of the year. It is suggested that such finger prints are produced by the corals themselves and not by the zooxanthellae, and that they are species-specific.     

Effects on growth and reproduction of the coral Stylophora pistillata by the mutualistic damselfish Dascyllus marginatus

Although coral dwelling fishes are common on coral reefs, the nature of their effect on the host corals is poorly understood. The present study, conducted in the Gulf of Eilat (Red Sea) between July 1989 and August 1990, demonstrated that the branching coral Stylophora pistillata (Esper) benefits, in two components of coral fitness, from the presence of the damselfish Dascyllus marginatus (Rüppell), an obligate coral dweller. The growth rate of damselfish-inhabited corals was significantly higher than that of corals without damselfish. This was observed, using two growth assessment methods, in long-term (>7 mo) comparisons between: (1) corals where the damselfish were experimentally removed versus corals with unaltered fish groups; and (2) naturally inhabited versus non-inhabited corals. The presence of damselfish did not affect the coral's specific (per surface area) reproductive output, whether it was assessed by the number of female gonads per polyp or by the number of planulae released cm^-2 surface area d^-1. However, the more rapid increase in branch size in damselfish-inhabited corals resulted in an apparent increase in the total reproductive output, with age, in growing corals. These findings demonstrate that the association between the damselfish D. marginatus and its host coral, S. pistillata, is mutualistic.     

Spawning and development of three coral-associated Lithophaga species in the Red Sea

Lithophaga date mussels from three species (L. lessepsiana, L. simplex and L. purpurea) were removed from their stony coral hosts in the Red sea at Eilat, Israel. Spawning, observed in the laboratory on several occasions during 1987–1988, appeared to be closely tied to lunar periods, occurring primarily during the last quarter and the new moon. Embryonic and larval development was typical of that described for other mytilids and, except for pigmentation differences, which could be discerned during embryogenesis, the developmental stages of the three species were indistinguishable. Development to the pediveliger stage took 3 to 4 wk in standard culture conditions, but raising the temperature to 27.5 °C increased the growth rate of larvae of L. lessepsiana by as much as three-fold, so that the pediveliger stage was attained in 16 d. Larvae resulting from spawning by L. simplex adults removed from the coral Astreopora myriophthalma grew significantly faster in culture than larvac from adults removed from the coral Goniastrea pectinata (comparison of slopes, p<0.05). The latter individuals showed a 6-d growth plateau at the early umbone stage. Metamorphically competent larvae were capable of delaying metamorphosis for up to 4mo, which would allow an extended period for dispersion and would increase the chance of finding a suitable substratum in the natural environment.     

Driving violations and health promotion behaviors among undergraduate students: Self-report of on-road behavior

Introduction: The purposes of this study are to characterize Israeli undergraduate students' driving violations in the terms of problem behavior theory and to identify whether there is any relationship between driving violations and health risk behaviors, daring behaviors, excitement seeking, and health promotion behaviors.

Methods: This study is based on a structured self-reported anonymous questionnaire distributed to undergraduate students in an academic institution. The sample included 533 undergraduate students (374 females and 159 males). The mean age was 23.4 (SD = 1.4, range = 5).

Results: A higher prevalence of self-reported driving violations was found among males in comparison to females. All substance use measures were positively related to driving violations; for example, use of cigarettes (OR = 4.287, P <.001) and water pipes (odds ratio [OR] = 3.000, P <.001) as well as binge drinking (OR = 5.707, P <.001) and regular cannabis smoking (OR = 5.667, P <.001) raise the probability of committing rare driving violations. The strongest predictive factors for the frequent driving violations group were alcohol consumption–related variables: binge drinking (OR = 2.560, P <.01) and drunkenness (OR = 2.284, P <.05). Strong odd ratios were also found between the frequent driving violations group and selling or dealing drugs (12.143, P <.001), and stealing something valuable (13.680, P <.001). The strongest predicted variable for the rare driving violations group was physical confrontation due to verbal disagreement (3.439, P <.05) and the concept that selling or dealing drugs is socially acceptable (2.521, P <.05). The probability of executing rare driving violations was higher for subjects who reported intense physical workout regimens (OR = 1.638, P <.05).

Conclusions: Problem behavior theory succeeded in explaining health risk behavior and driving violations. This study shows that bachelors tend to be more involved in risk behaviors, such as substance use, excitement-seeking behaviors, and daring behaviors and are active physically and thus constitute a risk group for driving violations. As such, intervention resources should be directed toward this group.     

Reproductive patterns of scleractinian corals in the northern Red Sea

The majority of published accounts on scleractinian coral reproduction are from the tropical Pacific and Caribbean, with very little information known about Red Sea species. This report examines variation in reproductive mode in 24 species of hermatypic corals (belonging to seven families) in the Gulf of Eilat, Red Sea. Eighteen species are hermaphroditic broadcasters, two are hermaphroditic brooders and three are gonochoric broadcasters. In the Pocilloporidae, the gonads project into the body cavity, while in the other six families the gonads reside inside the mesenteries. The number of gonads per polyp in broadcasting species follows family or genus lines. Fecundity (eggs per polyp) increases with polyp size. Brooding species usually exhibit one or two gonads per polyp and each gonad contains only one to three oocytes. Oocyte size varies widely and does not relate to mode of reproduction. The largest oocytes (diameter = 450 μm) occur in the brooding coral Alveopora daedalea and in broadcasting species of the genus Acropora (diameter = 420 μm). Gonad morphology and gonochorism versus hermaphroditism appear to be constrained phylogenetically at the family or genus level. Lastly, this report compares the data presented for Red Sea scleractinian species with the data available on scleractinian corals from other geographical regions. Received: 2 February 1993 / Accepted: 9 March 1998     

Degradation and proliferation of zooxanthellae in planulae of the hermatypic coral Stylophora pistillata

Zooxanthellae in different stages of two opposite processes, degradation and proliferation, were found in the planulae of hermatypic corals. The formation of new zooxanthellae is balanced by degraded zooxanthellae in newly released planulae. The number of dividing zooxanthellae and degraded zooxanthellae during the day amounted to approximately 2 to 3% of the standing stock. In settled planulae and particularly in motionless planulae of Stylophora pistillata (Esper, 1797), the degraded zooxanthellae outnumbered proliferous zooxanthellae. The proliferation and degradation of zooxanthellae and the extrusion of degraded remnants of zooxanthellae are significantly phased. Swimming planulae are more autotrophic than motionless planulae. The physiological parameters of settled planulae with exoskeleton are similar to those of adult polyps. The significance of zooxanthella degradation in the vital functions of planulae is discussed. We suggest that the degradation of zooxanthellae in planulae occurs by the digestion of symbionts by host cells. Received: 5 March 1997 / Accepted: 6 August 1997     

Tissue regeneration in the coral Fungia granulosa: the effect of extrinsic and intrinsic factors

To understand how regeneration in corals may be affected by intrinsic and extrinsic factors, the process of repair of experimentally induced tissue lesions was investigated in the solitary scleractinian coral Fungia granulosa. Three lesion sizes were inflicted in situ on large, sexually mature individuals (>5.5 cm diameter) and in small sexually immature (<5.0 cm) individuals. Repair was monitored using photography and computerized image analysis. This procedure was carried out in fall (September to November; post-reproductive months), and repeated with a new set of corals in spring (March to May; gametogenic months). Reproductive effort was investigated histologically 1 to 2 months following lesion infliction. In field experiments, there was a significant difference in percent of tissue coverage 8 weeks after lesion infliction between spring and fall for all lesion sizes in large corals. During the fall, all lesion sizes in large corals were repaired within 8 weeks. Large lesions in small corals did not undergo repair regardless of season. During the spring, none of the corals underwent complete repair regardless of coral size, and many of the small corals died. In laboratory experiments, 83.3% of the corals kept at 25 °C and 16.7% of those kept at 21 °C underwent repair during the fall. None of the corals maintained at 21 °C and only 16.7% of those corals maintained at 25 °C underwent complete repair during spring. Though both fecundity and tissue regeneration were significantly reduced, gametogenesis continued in corals that had previously undergone experimental injury. These results indicate that in fungiid corals, regeneration is affected by intrinsic factors such as size and reproductive state as well as by environmental factors such as ambient water temperatures. Moreover, it is possible that, following injury, energetic resources are diverted from repair towards the maintenance of reproductive effort. Received: 21 March 2000 / Accepted: 28 July 2000     

Antimicrobial activity of Red Sea corals

Scleractinian corals and alcyonacean soft corals are the two most dominant groups of benthic marine organisms inhabiting the coral reefs of the Gulf of Eilat, northern Red Sea. Antimicrobial assays performed with extracts of six dominant Red Sea stony corals and six dominant soft corals against marine bacteria isolated from the seawater surrounding the corals revealed considerable variability in antimicrobial activity. The results demonstrated that, while the majority (83%) of Red Sea alcyonacean soft corals exhibited appreciable antimicrobial activity against marine bacteria isolated from the seawater surrounding the corals, the stony corals had little or no antimicrobial activity. From the active soft coral species examined, Xenia macrospiculata exhibited the highest and most potent antimicrobial activity. Bioassay-directed fractionation indicated that the antimicrobial activity was due to the presence of a range of compounds of different polarities. One of these antibiotic compounds was isolated and identified as desoxyhavannahine, with a minimum inhibitory concentration (MIC) of 48 μg ml⁻¹ against a marine bacterium. The results of the current study suggest that soft and hard corals have developed different means to combat potential microbial infections. Alcyonacean soft corals use chemical defense through the production of antibiotic compounds to combat microbial attack, whereas stony corals seem to rely on other means.