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1.
    
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.  相似文献   

2.
    
Mounting evidence shows that artificial light at night (ALAN) alters biological processes across levels of organization, from cells to communities. Yet, the combined impacts of ALAN and natural sources of night-time illumination remain little explored. This is in part due the lack of accurate simulations of the complex changes moonlight intensity, timing and spectra throughout a single night and lunar cycles in laboratory experiments. We custom-built a novel system to simulate natural patterns of moonlight to test how different ALAN intensities affect predator–prey relationships over the full lunar cycle. Exposure to high intensity ALAN (10 and 50 lx) reversed the natural lunar-guided foraging pattern by the gastropod mesopredator Nucella lapillus on its prey Semibalanus balanoides. Foraging decreased during brighter moonlight in naturally lit conditions. When exposed to high intensity ALAN, foraging increased with brighter moonlight. Low intensity ALAN (0.1 and 0.5 lx) had no impact on foraging. Our results show that ALAN alters the foraging pattern guided by changes in moonlight brightness. ALAN impacts on ecosystems can depend on lunar light cycles. Accurate simulations of night-time light cycle will warrant more realistic insights into ALAN impacts and also facilitate advances in fundamental night-time ecology and chronobiology.  相似文献   

3.
Abstract

The endogenous activity cycle of the nocturnal bannertail kangaroo rat was investigated. Although bannertail activity is a function of the lunar day as well as the solar day, all ten subjects exhibited free‐running activity periods of solar‐day length; there was no evidence of an endogenous lunar‐day cycle. Animals were provided with a burrow system and a small pseudo‐desert, a laboratory facility in which animal activity data closely resembled measurements taken in the field. Several analytical techniques for quantifying the data were utilized, and one, the mean interval of activity, is recommended to other investigators.  相似文献   

4.
5.
Little is known about the reproductive biology of corals from the Philippines, despite this archipelago being at the center of coral reef biodiversity. Here, we report on the reproductive biology of a branching poritid species provisionally identified as Porites cf. cylindrica in the Bolinao‐Anda reef complex (BARC), northwestern Philippines. Histological examination and ex situ planulation observations reveal P.cf. cylindrica colonies to be gonochoric brooders that release actively swimming zooxanthellate larvae. Planulation appeared to occur throughout the year and there was significant lunar periodicity in planular release. The mean peak of release occurred from the 25th to 29th lunar day or just before the new moon, while peak in diel timing in planulation occurred during daytime between 08:00–11:00 h. Elsewhere in the Pacific, Porites cylindrica colonies are reported to broadcast spawn. If our species identification is correct, then this is the first report of brooding in P. cylindrica. Although there are no apparent morphological differences between the coral in this study and P. cylindrica reported from other sites, an alternative explanation for our findings is that our provisionally identified Porites cf. cylindrica is a different species. If so, our findings further highlight how difficulties with species identification in corals can influence our understanding of geographical variation in reproductive biology.  相似文献   

6.
    
Diet composition of the southern Ray's bream Brama australis was examined from stomach contents of 399 specimens sampled by bottom trawl on Chatham Rise to the east of South Island, New Zealand, over 3 years. Prey items were predominantly mesopelagic fishes and crustaceans. Multivariate analysis indicated that moon phase explained more of the diet variability than any other predictor examined. It appears likely that diet composition is influenced by a combination of changes in both tidal flows and illumination. Different combinations of prey were consumed by B. australis at different times of the lunar cycle. An influence of moon phase on feeding by fishes has rarely been reported, but it is likely that moon phase influences the diets of other species that specialize in mesopelagic prey. The most important prey group by mass for B. australis was Myctophidae (primarily Lampanyctodes hectoris), followed by Stomiiformes (primarily Maurolicus australis) and shrimps (Sergestes spp). An ontogenetic shift in diet was observed, from numerical dominance by small crustaceans including amphipods and euphausiids (with some fishes) in smaller (mass <1045 g) B. australis to pelagic teleost prey (with a few larger crustaceans) in larger (>1440 g) B. australis.  相似文献   

7.
Although most countries have ethical guidelines for research involving human subjects and other sentient animals, the ethical issues associated with field research have received little attention. Most experimental marine biologists and ecologists operate without ethical guidelines or scrutiny, despite intermittent community concern about their activities. We offer suggestions on how marine biologists and ecologists can protect the future of research involving the field collection and experimental manipulation of organisms by developing mechanisms to address community concerns that such research is ethically responsible. We urge experimental marine biologists and ecologists to take pre-emptive initiatives by encouraging: (1) institutional animal ethics committees to broaden their terms of reference to include environmental ethics; (2) scientific societies to develop codes of ethics to guide the environmental research conducted by their members; (3) editorial boards of journals to require the research they publish to conform to an appropriate code of ethics, and (4) management agencies that issue permits for field research to establish an ethics committee to advise them on the ethical issues raised by specific research proposals. We conclude that the resultant administrative burden on scientists would be low but that the penalties of operating without such protection can be high.  相似文献   

8.
9.
    
ABSTRACT Densities and diversity of gymnamoebae are reported for three sites at Bermuda. Two are marine sites in Mullet Bay, and the third is a shallow pond (Ferry Reach Park), Bermuda. Site 1 (edge of a small island in Mullet Bay) had higher densities of gymnamoebae (28,761/g sediment) than at a disturbed site 2 (17,597/g), a boat mooring. The diversity was higher, however, at site 2 (H = 4.3) compared to site 1 (H = 3.3). The site 2 species were larger including morphotypes categorized as type 1 (e.g. Mayorella and a reticulate amoeba). The brackish inland pond had higher abundances in the sediments (40.590/g) compared to the marine habitats. However, the diversity was lower (H = 2.7) and it was dominated largely by Vannella and Platyamoeba (categorized as morphotype 4). These data are consistent with findings at continental coastal locations in northeastern USA. Pond sediments generally contain higher densities of gymnamoebae than marine coastal sediments with less organic content. The ratio of type 4 to type 1 amoebae in pond samples is higher than those from coastal sites. The data from Bermuda, an open ocean insular site, provide additional zoogeographic evidence for the generality of these patterns of abundance.  相似文献   

10.
    
Yankee whalers of the 19th century had major impacts on populations of large whales, but these leviathans were not the only taxa targeted. Here, we describe the “collateral damage,” the opportunistic or targeted taking of nongreat whale species by the American whaling industry. Using data from 5,064 records from 79 whaling logs occurring between 1840 and 1901, we show that Yankee whalers captured 5,255 animals across three large ocean basins from 32 different taxonomic categories, including a wide range of marine and terrestrial species. The taxa with the greatest number of individuals captured were walruses (Odobenus rosmarus), ducks (family Anatidae), and cod (Gadus sp.). By biomass, the most captured species were walruses, grampus (a poorly defined group within Odontoceti), and seals (family Otariidae). The whalers captured over 2.4 million kg of nongreat whale meat equaling approximately 34 kg of meat per ship per day at sea. The species and areas targeted shifted over time in response to overexploitation of whale populations, with likely intensive local impacts on terrestrial species associated with multiyear whaling camps. Our results show that the ecosystem impacts of whaling reverberated on both marine and coastal environments.  相似文献   

11.
12.
Abstract. 1. The diurnal periodicity of flight of delphacids and cicadellids associated with rice was assessed by suction trapping.
2. All the delphacids examined and most cicadellids showed a bimodal, crepuscular pattern of flight, the major peak occurring in the evening.
3. Some cicadellids showed a unimodal crepuscular pattern of flight activity with the peak occurring in the evening, whereas flight activity of Cofana spectra and Cunimaculata continued throughout the night.
4. Changes in the periodicity of flight activity of Nilaparvata lugens, Sogatella furcifera, Recilia dorsalis and Macrosteles striifrons were observed in relation to phases of the moon and the nature of the habitat.
5. Periodicity of take-off for N.lugens, Sfurcifera and R.dorsalis assessed by canopy net traps also showed a bimodal, crepuscular pattern with the major peak occurring in the evening.
6. The significance of diurnal periodicity is discussed in relation to the flight behaviour of the insects studied.  相似文献   

13.
  总被引:1,自引:0,他引:1  
Testosterone, 11-ketotestosterone and 17α ,20β-dihydroxy-4-pregnen-3-one in the forktail rabbitfish Siganus argenteus peaked around the full moon and the last quarter moon, respectively. Since changes in these hormones were correlated with histological change in the testis, the present study provided conclusive evidence for importance of the lunar periodicity in the reproductive activity of the forktail rabbitfish.  相似文献   

14.
    
We used acoustic telemetry to quantify permit Trachinotus falcatus habitat use and connectivity in proximity to the Florida Keys, USA, and assessed these patterns relative to current habitat and fisheries management practices. From March 2017 to June 2018, 45 permit tagged within 16 km of the lower Florida Keys were detected at stationary acoustic receivers throughout the south Florida region, the majority of which remained within the Special Permit Zone, where more extensive fisheries harvest regulations are implemented. There was a high level of connectivity between nearshore flats (i.e., <3 m water depth) and the Florida reef tract (FRT; 15–40 m water depth), with 75% of individuals detected in both habitats. These locations probably function primarily as foraging and spawning habitats, respectively. Permit occupancy on the FRT peaked during the months of March–September, with the highest number of individuals occurring there in April and May. Specific sites on the FRT were identified as potentially important spawning locations, as they attracted a high proportion of individuals that exhibited frequent visits with high residency durations. There were also significant positive relationships between seasonal habitat-use metrics on the FRT and an empirical permit gonadosomatic index. Large aggregations of permit at spawning sites on the FRT are potentially vulnerable to the effects of fishing (including predation during catch and release) at a critical point in their life cycle. These data on permit space use and movement, coupled with knowledge of stressors on their ecology, provide insights for implementing science-based strategic management plans.  相似文献   

15.
    
Growth and survival of larval fishes is highly variable and unpredictable. Our limited understanding of this variation constrains our ability to forecast population dynamics and effectively manage fisheries. Here we show that daily growth rates of a coral reef fish (the sixbar wrasse, Thalassoma hardwicke) are strongly lunar-periodic and predicted by the timing of nocturnal brightness: growth was maximized when the first half of the night was dark and the second half of the night was bright. Cloud cover that obscured moonlight facilitated a ‘natural experiment’, and confirmed the effect of moonlight on growth. We suggest that lunar-periodic growth may be attributable to light-mediated suppression of diel vertical migrations of predators and prey. Accounting for such effects will improve our capacity to predict the future dynamics of marine populations, especially in response to climate-driven changes in nocturnal cloud cover and intensification of artificial light, which could lead to population declines by reducing larval survival and growth.  相似文献   

16.
17.
We observed hatching behavior by mouthbrooding males of the cardinalfish, Apogon niger. Mouthbrooding males showed no feeding activities at night, in spite of their nocturnal feeding habit. On the day of hatching, they released newly hatched larvae from their mouths on average 81 min after sunset. Semilunar hatching periodicity was significant, but its diel pattern was independent of the tidal rhythm. Sunset hatching may be advantageous not only to offspring because of their low predation risk but also to parental males because they can resume feeding sooner, thereby reducing the energetic loss from fasting while mouthbrooding. Received: August 22, 2000 / Revised: November 28, 2000 / Accepted: January 12, 2001  相似文献   

18.
生态学研究的新领域--分子生态学   总被引:4,自引:0,他引:4  
分子生态是生态学的一个新的研究领域。它采用分子生物学的技术与方法来研究生态活动规律的分子机理。本文简要介绍了分子生态学的定义、研究内容、研究方法和研究热点等,以期描述出分子生态学的概貌。  相似文献   

19.
    
Diel patterns of photosynthesis and cell division were examined in Thalassiosira weissflogii Grun. (clone Actin) grown in nitrogen-limited cyclostat culture. Ammonia (NH4+) was either supplied continuously or as a daily pulse to cultures grown in constant light or in a light: dark cycle. When either nitrogen or light was supplied periodically, both cell division and photosynthetic capacity were periodic. When both nitrogen and light were supplied periodically, cell division was coupled to the N-pulse whereas periodicities of photosynthetic capacity were modified but remained coupled to the light-dark cycle. Diel oscillations in photosynthesis were i) largely independent of cellular pigmentation and ii) similar for light-limiting and saturating irradiances. Periodicity in photosynthetic capacity also persisted following transfer of non-dividing batch cultures to constant light. Results suggest that photosynthesis but not cell division was coupled to a circadian clock in T. weissflogii. A circadian rhythm of photosynthesis may optimize carbon assimilation in phytoplankton exposed to intermittent nutrient supply by ensuring that maximum photosynthetic capacity occurs during the day.  相似文献   

20.
    
Beliefs that lunar phases affect human physiology started in ancient times. Research has recently revealed that a physical fitness index increased in sedentary students at the new moon (NM) and full moon (FM) compared to other moon phases. However, the effect of lunar cycle (moon illumination and gravitational pull) on physical performance in athletes was not examined. Therefore, this study aimed to evaluate whether short-term explosive performance can be influenced by the different phases of the lunar cycle. Fourteen young male Taekwondo athletes (age: 16.9 ± 0.7 years, height: 159.7 ± 50.6 cm, body mass: 62.85 ± 7.84 kg) performed the following tests to assess the explosive physical performance during the different phases of the lunar cycle (NM, FQ (first quarter), FM, and LQ (last quarter)): maximal isometric manual contraction (dominant hand (MIMCD) and non-dominant hand (MIMCND)), maximal back isometric contraction (MBIC), squat jump (SJ), countermovement jump (CMJ), and 10-m sprint (10 m). The testing sessions during the different moon phases were performed in a counterbalanced order. The order of tests remained the same (MIMCD, MIMCND, MBIC, SJ, CMJ, and 10 m), and all sessions were performed in the evening (6:00 to 8:00 p.m.) on the first day of each evaluated lunar phase. Each parameter was measured over two consecutive lunar months in the calendar. Analysis of variance tests showed that there was no significant effect of lunar cycle on all explosive test measures, p > 0.05. Our results failed to identify any effect of lunar phase on evening explosive performance (mainly involving phosphagen pathway-based efforts) among young trained athletes. Therefore, it appears that moon phase/illumination does not affect short-term physical performance in young trained adolescents.  相似文献   

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