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Lunar Cycle (lunar + cycle)
Selected AbstractsHABITAT DIFFERENCES IN THE TIMING OF REPRODUCTION OF THE INVASIVE ALGA SARGASSUM MUTICUM (PHAEOPHYTA, SARGASSACEAE) OVER TIDAL AND LUNAR CYCLES,JOURNAL OF PHYCOLOGY, Issue 1 2009Carla Monteiro Sargassum muticum (Yendo) Fensholt is an invasive species that is firmly established on intertidal and subtidal rocky shores of Europe and the Pacific coast of North America. Local success and spread of S. muticum is thought to rely on its reproductive potential that seems dependent on exogenous factors like tidal and lunar cycles. This study is the first to compare the reproductive patterns (periodicity of egg expulsion and embryo settlement) of this invader in two different habitats: the middle and low intertidal. The combination of monthly, daily, and tidal samples at triplicate sites within each habitat showed a semilunar periodicity of egg expulsion and embryo settlement coincident with increasing tidal amplitude just before full and new moons. In both habitats, duration of each egg expulsion event was ,1 week, and embryo settlement occurred during the first daily low tide and with the incoming high tide during spring tides. However, both expulsion and settlement started 1,2 d earlier, expulsion saturation was faster, and settlement was higher in the mid- compared to the low intertidal. Our results suggest that the exact timing of gamete expulsion and embryo release of S. muticum responds to local factors, including tidal cues, which result in differences between mid- and low-intertidal habitats. [source] Lunar cycles and reproductive activity in reef fishes with particular attention to rabbitfishesFISH AND FISHERIES, Issue 4 2004Akihiro Takemura Abstract Cues from the moon influence synchrony in growth, feeding, migration, behaviour and reproduction of many reef fishes. Compared with comprehensive studies on the annual and daily activities of fish, few physiological studies have paid attention to the importance of lunar cues in reproductive activities. We review mutual and interesting relationships between fish reproduction and environmental changes induced by the moon, with particular emphasis on the reproductive activity of the rabbitfishes (Siganidae). Rabbitfish species exhibit, in nature, a definitive reproductive season, which differs among the tropical areas. During the reproductive season, synchronous spawning of rabbitfish is associated with a particular lunar phase. The lunar phase used by the respective species is similar in different regions on the earth. Histological observations revealed that gonads develop synchronously towards a peak around the spawning lunar phase, after which the gonads return to spent condition. Concomitant with gonadal development, sex steroid hormones were produced under the influence of gonadotropin (GtH). Injections of human chronic gonadotropin (hCG) to the fish that are undergoing active spermatogenesis accelerated testicular maturation. These results suggest that hormonal response in maturing the gonads in rabbitfish is under the regulation of GtH, and that pituitary secretion of GtH according to the lunar cycle accounts for the lunar rhythm in gonadal development. We speculate that the cues from the moon can be recognized by the higher parts of the hypothalamus,pituitary,gonadal axis. Possible relationships between exogenous environmental factors and the lunar-reproductive rhythm are also discussed. [source] The influence of the lunar cycle on fertility on two Thoroughbred studfarmsEQUINE VETERINARY JOURNAL, Issue 1 2000N. Kollerstrom No abstract is available for this article. [source] Natural variability of fisheries and lunar illumination: a hypothesisFISH AND FISHERIES, Issue 2 2008Santiago Hernández-León Abstract Long-term synchronous trends in small pelagic fisheries catches around the world suggest that fish populations are governed by the same global climate forcings. Recent findings regarding the population dynamics of zooplankton during the lunar cycle in sub-tropical waters may shed light on the influence of the lunar cycle on fish spawning and mortality. Here I hypothesize that, in the short-term, observed changes in zooplankton abundance during the lunar cycle promote periods of enhanced feeding by adult fish and lower mortality (and increased growth) in their early planktonic stages. Furthermore, a striking 9-year periodicity in sardine and anchovy mortality was inferred in four major upwelling areas, coinciding with the long-term variability in lunar illumination. It is suggested that both short- and long-term changes in lunar illumination should be considered when modelling the effect of climate on the natural variability of fisheries. [source] Antisymmetry in male fiddler crabs and the decision to feed or breedFUNCTIONAL ECOLOGY, Issue 1 2002A. E. Pratt Summary 1,In male Sand Fiddler Crabs, Uca pugilator, a major cheliped (with claw), used in intersexual displays and intrasexual contests, develops opposite a minor cheliped used for feeding. Cheliped size demonstrates antisymmetry because greater development is equally likely on the right or left side. 2,The side with the major cheliped (major side) also has longer walking legs which may facilitate use of the claw. In contrast, eye stalk asymmetry is equally due to antisymmetry and fluctuating asymmetry. Fluctuating asymmetry is a subtle, non-adaptive departure from the population-level trajectory relating growth on major and minor sides. 3,In a South Carolina (USA) marsh, cheliped and leg antisymmetries are greater and eye stalk asymmetry is less among males able to defer feeding in favour of breeding. However, the composition of up-slope breeding and down-slope feeding subpopulations changes across the lunar cycle. 4,The number of mates sequestered in breeding burrows is positively correlated with cheliped and leg antisymmetry and negatively correlated with eye stalk asymmetry. Male fitness is a function of the product of time spent breeding and the number of mates per unit time while breeding. Both fitness components are predicted by relative cheliped antisymmetry and eye stalk fluctuating asymmetry, which are themselves significantly negatively correlated. [source] Oceanic migration and spawning of anguillid eelsJOURNAL OF FISH BIOLOGY, Issue 9 2009K. Tsukamoto Many aspects of the life histories of anguillid eels have been revealed in recent decades, but the spawning migrations of their silver eels in the open ocean still remains poorly understood. This paper overviews what is known about the migration and spawning of anguillid species in the ocean. The factors that determine exactly when anguillid eels will begin their migrations are not known, although environmental influences such as lunar cycle, rainfall and river discharge seem to affect their patterns of movement as they migrate towards the ocean. Once in the ocean on their way to the spawning area, silver eels probably migrate in the upper few hundred metres, while reproductive maturation continues. Although involvement of a magnetic sense or olfactory cues seems probable, how they navigate or what routes they take are still a matter of speculation. There are few landmarks in the open ocean to define their spawning areas, other than oceanographic or geological features such as oceanic fronts or seamounts in some cases. Spawning of silver eels in the ocean has never been observed, but artificially matured eels of several species have exhibited similar spawning behaviours in the laboratory. Recent collections of mature adults and newly spawned preleptocephali in the spawning area of the Japanese eel Anguilla japonica have shown that spawning occurs during new moon periods in the North Equatorial Current region near the West Mariana Ridge. These data, however, show that the latitude of the spawning events can change among months and years depending on oceanographic conditions. Changes in spawning location of this and other anguillid species may affect their larval transport and survival, and appear to have the potential to influence recruitment success. A greater understanding of the spawning migration and the choice of spawning locations by silver eels is needed to help conserve declining anguillid species. [source] Diel spawning periodicity of red snapper Lutjanus campechanus in the northern Gulf of MexicoJOURNAL OF FISH BIOLOGY, Issue 3 2006M. W. Jackson Ovaries of red snapper Lutjanus campechanus were examined histologically to determine rates of oocyte maturation, diel spawning periodicity and whether lunar cycle influenced spawning rhythm. Hydration of red snapper oocytes began during the mid-morning hours; c. 5 h was necessary for oocytes to become fully hydrated and ovulation occurred no more than 5 h after oocytes attained full hydration. Appearance of fresh postovulatory follicles after 1330 hours and the absence of hydrated oocytes after 1830 hours signified that red snapper spawning occurred during this 5 h period. In addition, evidence of a peak in spawning was seen near 1600 hours. Postovulatory follicles degenerated within a 24 h time period. A lunar spawning cycle was not evident. [source] Reproductive behaviour of a temperate serranid fish, Paralabrax clathratus(Girard), from Santa Catalina Island, California, U.S.A.JOURNAL OF FISH BIOLOGY, Issue 1 2006B. E. Erisman The reproductive behaviour of the kelp bass Paralabrax clathratus was studied on Santa Catalina Island, California, U.S.A. from April 2000 to September 2002. Adults formed aggregations of three to > 200 individuals, and spawning occurred within subgroups of three to 23 individuals that contained a single female. The gonado-somatic index (IG) of collected ripe males (mean = 5·8%, range = 0·5,13·1%) indicated a large investment in sperm production that is common in group-spawning fishes characterized by intense sperm competition. Spawning occurred 32 min before sunset to 120 min after sunset, and both males and females were capable of spawning multiple times during a single evening. Behavioural observations of adults and estimates of spawning periodicity from the collection of females with hydrated oocytes suggested that spawning occurred continuously throughout the summer months and showed no significant relationship with the lunar cycle. In general, the spawning behaviour of kelp bass was similar to other functionally gonochoric, group-spawning serranids. The dynamics of P. clathratus spawning aggregations, however, were inconsistent with that of tropical reef fish spawning aggregations, including the transient spawning aggregations of some tropical serranids. Aggregation spawning appeared to be an important component of the annual reproduction of this species. [source] Trade-off between resource seasonality and predation risk explains reproductive chronology in impalaJOURNAL OF ZOOLOGY, Issue 3 2007S. R. Moe Abstract We investigated the variation in birth synchrony displayed by impala Aepyceros melampus populations across their distribution from southern to eastern Africa. Our analysis was based on field data from Chobe National Park in Botswana and Mala Mala Private Game Reserve in South Africa (4 and 13 years of monitoring, respectively). We compared our results with those from other studies conducted across the impala species range. Impala lambing was highly synchronized in Chobe with 90% of lambs born within 2 weeks in mid-November. Variation in rainfall in the preceding wet season explained 74% of variation in the dates of the first lamb observation in Mala Mala. In Chobe, the earliest birth peak occurred after the highest rainfall and the body condition of lambs in that cohort was also best for both males and females. No association was found between the lunar cycle and the estimated onset of the conception period, despite previous studies having found an association between the lunar cycle and the rutting behaviour in males. On a regional scale, impalas in areas with a marked dry season (several months with no rain) tend to synchronize births with the onset of the rains, when grass quality is highest. Number of months with rain explained 78% of the regional variation in birth synchrony. Neither latitude nor total rainfall contributed significantly to a stepwise multiple regression model. These data support the theory that impalas synchronize births in areas with a highly seasonal food supply, and temporally space births in less seasonal (equatorial) areas to reduce predation risks. [source] The epidemiology and chronobiology of epistaxis: an investigation of Scottish hospital admissions 1995,2004CLINICAL OTOLARYNGOLOGY, Issue 5 2007T.W.M. Walker Objectives:, This study aimed at investigating aspects of the epidemiology and chronobiology of emergency admissions with epistaxis in Scotland between 1995 and 2004. In particular, we sought to examine the epidemiology of hospital admission with epistaxis and effects of factors such as day of week, time of year and lunar cycle. Design:, A statistical analysis, in terms of descriptive statistics, logistical regression and linear regression, was carried out on data obtained from the Scottish Morbidity Records related to emergency Ear, Nose and Throat (ENT) admissions. Setting and participants:, All emergency inpatient admissions for Scottish residents to ENT wards in Scottish NHS hospitals during the 10-year period, between 1st January 1995 and December 31st 2004 were studied. This study only looked at admissions and thus excludes Accident and Emergency attendances caused by epistaxis. Main outcome measures:, Age, gender, year, month and day of the week of admission were considered, as was relationship to the moon phase. Results:, During the study period, the mean daily admission rate with epistaxis was six. Epistaxis accounted for 33% of all ENT emergency admissions. The average age of non-epistaxis ENT emergency admission was 31 years. For epistaxis emergency admissions the median age was 70 years. There were fewer admissions in the summer months [August RR: 0.59 (95% CI: 0.54,0.65) P < 0.001]. There were more admissions at the weekends and on non-weekend public holidays [RR: ,0.115 (95% CI ,0.160,0.071) P < 0.001]. There was a trend towards a reduction in admission rates from the year 2001. Despite the fluctuations with season and weekday, there was no relationship with phase of the moon [RR: 0.98 (95% CI: 0.88,1.09) for day of the full moon compared with non-full moon weekday]. Conclusions:, This study underlines the importance of epistaxis as the single most frequent emergency diagnosis in ENT. The frequency and patterns of admission show pronounced fluctuations. The observed increase in winter admissions confirms earlier work and may have implications for health resource allocation. Relationships between weekends/public holidays and increased admissions with epistaxis may correspond with social patterns of alcohol use (a known aetiological factor). The lunar cycle does not have an effect on the frequency of epistaxis admissions. [source] Moon phase and nocturnal density of Atlantic salmon parr in the Sainte-Marguerite River, QuébecJOURNAL OF FISH BIOLOGY, Issue 1 2005I. Imre Nocturnal underwater counts of Atlantic salmon Salmo salar parr were made on four consecutive occasions (two lunar cycles, samplings at both the full and new moon) at four 40 m long sites in the Sainte-Marguerite River, Québec, Canada, between 30 June and 14 August 2003. Atlantic salmon parr counts did not differ significantly between moon phases. Cloud cover ranged from 0 to 100% during the study, and had no significant effect on parr counts. There were significantly more Atlantic salmon parr in the near shore than in the midstream areas. The findings of this study suggest that the sampling strategy of summer studies aimed at assessing population abundance or developing habitat quality models can be designed without taking moon phase or cloud cover into consideration, but it should account for the higher relative abundance of Atlantic salmon parr in the near shore areas as compared to areas closer to the middle of streams. [source] HABITAT DIFFERENCES IN THE TIMING OF REPRODUCTION OF THE INVASIVE ALGA SARGASSUM MUTICUM (PHAEOPHYTA, SARGASSACEAE) OVER TIDAL AND LUNAR CYCLES,JOURNAL OF PHYCOLOGY, Issue 1 2009Carla Monteiro Sargassum muticum (Yendo) Fensholt is an invasive species that is firmly established on intertidal and subtidal rocky shores of Europe and the Pacific coast of North America. Local success and spread of S. muticum is thought to rely on its reproductive potential that seems dependent on exogenous factors like tidal and lunar cycles. This study is the first to compare the reproductive patterns (periodicity of egg expulsion and embryo settlement) of this invader in two different habitats: the middle and low intertidal. The combination of monthly, daily, and tidal samples at triplicate sites within each habitat showed a semilunar periodicity of egg expulsion and embryo settlement coincident with increasing tidal amplitude just before full and new moons. In both habitats, duration of each egg expulsion event was ,1 week, and embryo settlement occurred during the first daily low tide and with the incoming high tide during spring tides. However, both expulsion and settlement started 1,2 d earlier, expulsion saturation was faster, and settlement was higher in the mid- compared to the low intertidal. Our results suggest that the exact timing of gamete expulsion and embryo release of S. muticum responds to local factors, including tidal cues, which result in differences between mid- and low-intertidal habitats. [source] | ||||||||||||||||