scholarly journals Constant timing of medusa release in bivalve-inhabiting hydrozoans of the genus Eugymnanthea (Hydrozoa: Leptomedusae: Eirenidae)

2008 ◽  
Vol 88 (8) ◽  
pp. 1607-1609 ◽  
Author(s):  
Shin Kubota
Keyword(s):  
Light Intensity ◽  
Water Temperature ◽  
Breeding Season ◽  
Laboratory Experiments ◽  
Mytilus Galloprovincialis ◽  
Congeneric Species ◽  
Natural Conditions ◽  
Night Time

At the end of the breeding season in autumn, under natural conditions, mature medusae of Eugymnanthea japonica are released from its host Mytilus galloprovincialis at night-time. In laboratory experiments, mature medusae of the congeneric species E. inquilina are also released at night-time in autumn. At that time of the year, sunset is earlier and the water temperature is lower than in summer, when, under natural conditions, medusa release of E. japonica takes place at sunset instead. The release thus takes place at the same hours of the day in summer as well as in autumn. The circadial timing of medusa release of E. japonica is likely constant throughout the whole period in the breeding season and not correlated with the decrease of light intensity at sunset.

Pigment variation in the photosynthetic sulfur bacterium Chlorobium phaeobactereoides from Lake Kinneret

2000 ◽  
Vol 42 (1-2) ◽  
pp. 423-427 ◽  
Author(s):  
Y.Z. Yacobi ◽  
E. Ben-Bassat ◽  
D. Murad ◽  
W. Eckert
Keyword(s):  
Light Intensity ◽  
Laboratory Experiments ◽  
Positive Relationship ◽  
Culture Collection ◽  
Lake Kinneret ◽  
Carotenoid Content ◽  
Natural Conditions ◽  
Pigment Variation ◽  
Bacteriochlorophyll E

The photosynthetic sulfur bacterium Chlorobium phaeobactereoides found in Lake Kinneret harbors three homologues of bacteriochlorophyll e (Bchl e). The ratios between the Bchl e homologues found in samples from the metalimnion are approximately constant and perennially stable. The proportion of Bchl e homologues in a laboratory isolate of Ch. phaeobactereoides was different from that found in the lake population, but resistant to changes in light, even if cultures were exposed to light intensity 2-3 orders of magnitude higher than the intensity experienced by the bacterium under natural conditions. Exposure of cultures in the lake did not induce changes in the proportion of pigments, indicating that the isolate maintained in the culture collection is intrinsically different from the genotypes that build up most of Ch.phaeobactereoides in Lake Kinneret. We found a positive relationship between light intensity and carotenoid content in laboratory experiments implying the photoprotective role of those compounds. The laboratory isolate also showed two unknown carotenoids, never found before in lake samples. Those carotenoids are less polar than -carotene, and showed absorption peaks at 427 and 451 nm, and 429 and 451 nm, in methanol.

Pelagic Amphipoda of the Belle Isle Strait Region

1951 ◽  
Vol 8b (3) ◽  
pp. 134-163 ◽  
Author(s):  
E. L. Bousfield
Keyword(s):  
Light Intensity ◽  
Breeding Season ◽  
Cold Water ◽  
Ocean Currents ◽  
Southern Limit ◽  
Index Species ◽  
Labrador Current ◽  
Themisto Libellula

The distribution of certain pelagic Amphipoda taken in the Belle Isle strait region during the summer of 1923 is correlated with ocean currents, light intensity and size of individuals. Hyperoche medusarum, Themisto libellula and Pseudalibrotus glacialis are index species of the cold Labrador current in the area. Hyperia galba and H. medusarum are presumably also cold water indicators. Themisto abyssorum in sizeable numbers, and Calliopius laeviusculus are related to waters of the gulf of St. Lawrence. Themisto libellula, T. compressa form compressa and T. compressa form bispinosa are more numerous, while T. abyssorum is less numerous at the surface during daylight than during darkness. Part of the breeding season of T. compressa and T. abyssorum occurs in the area during August and September, when the young of both species are much more numerous than the adults, particularly at the surface. A new southern limit of distribution for P. glacialis is established. The known distribution of the tropical genus Phronima is extended into the gulf of St. Lawrence.

The effects of age, temperature, light quantity and wavelength on the swimming behaviour of the cercariae of Cryptocotyle lingua (Digenea: Heterophyidae)

Parasitology ◽  
1992 ◽  
Vol 105 (1) ◽  
pp. 131-137 ◽  
Author(s):  
J. G. Rea ◽  
S. W. B. Irwin
Keyword(s):  
Life Span ◽  
Water Temperature ◽  
Light Source ◽  
Laboratory Experiments ◽  
Temperature Dependent ◽  
Release Point ◽  
Successful Transmission ◽  
Active Life ◽  
Light Quantity ◽  
Precipitous Decline

Laboratory experiments indicated that the active life-span of the cercariae of Cryptocotyle lingua was temperature-dependent. An increase in water temperature and population age both correlated with a tendency for the organisms to become decaudate. The larvae were strongly photoresponsive to lateral light but with time, horizontal swimming rates (HSRs) from release point to light source progressively declined. When measured over a range of light quantities, HSRs peaked at 30 μM/m2/s. HSRs were also influenced by water temperature. A rapid increase occurred up to 15 °C after which there was a precipitous decline. HSRs to coloured light were negatively correlated with increasing wavelength. When offered a choice between colours, cercariae favoured the shorter wavelengths. The implications of these responses for successful transmission are discussed.

DMSP/OLS night-time light intensity as an innovative indicator of regional sustainable development

2018 ◽  
Vol 40 (4) ◽  
pp. 1594-1613 ◽  
Author(s):  
Chang Li ◽  
Guie Li ◽  
Guofeng Tao ◽  
Yujia Zhu ◽  
Yijin Wu ◽  
...  
Keyword(s):  
Sustainable Development ◽  
Light Intensity ◽  
Night Time ◽  
Regional Sustainable Development

scholarly journals Fleshy Red Algae Mats Influence Their Environment in the Mediterranean Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Neele Schmidt ◽  
Yusuf C. El-Khaled ◽  
Felix I. Roßbach ◽  
Christian Wild
Keyword(s):  
Environmental Factors ◽  
Light Intensity ◽  
Water Temperature ◽  
Mediterranean Sea ◽  
Water Column ◽  
Red Algae ◽  
Water Movement ◽  
Ecosystem Engineer ◽  
Overlying Water ◽  
The Mediterranean

In the Mediterranean Sea, the fleshy red alga Phyllophora crispa forms dense mats of up to 15 cm thickness, mainly located on rocky substrates in water depths below 20 m. Because of the observed density of these mats and some first observations, we hypothesize that P. crispa is a yet undescribed ecosystem engineer that provides a multitude of ecological niches for associated organisms along small-scale environmental gradients. Therefore, we conducted an in-situ pilot study in the Western Mediterranean Sea to assess potential influence of the algae mats on the key environmental factors water movement, temperature and light intensity. We comparatively and simultaneously measured in P. crispa mats, in neighboring Posidonia oceanica seagrass meadows, on neighboring bare rocky substrates without algae mats, and in the directly overlying water column. We used several underwater logging sensors and gypsum clod cards. Findings revealed that P. crispa significantly reduced water movement by 41% compared to the overlying water column, whereas water movement was not affected by P. oceanica meadows and bare rocky substrates. Surprisingly, P. crispa increased the water temperature by 0.3°C relative to the water column, while the water temperature in P. oceanica and on bare rocky substrates was reduced by 0.5°C. Light intensity inside the red algae mats was reduced significantly by 69% compared to the water column. This was similar to measured light reduction of 77% by P. oceanica. These findings highlight the strong influence of the dense red algae mats on some key environmental factors. Their influence is obviously similar or even higher than for the well-known seagrass ecosystem engineer. This may be a factor that facilitates associated biodiversity similarly as described for P. oceanica.

Environmental control of reproduction in Perinereis nuntia var. brevicirrus

1994 ◽  
Vol 74 (4) ◽  
pp. 903-918 ◽  
Author(s):  
J.D. Hardege ◽  
H.D. Bartels-Hardege ◽  
Y. Yang ◽  
B.L. Wu ◽  
M.Y. Zhu ◽  
...  
Keyword(s):  
Water Temperature ◽  
Rocky Shore ◽  
Sex Pheromones ◽  
Laboratory Experiments ◽  
Environmental Control ◽  
Early Morning ◽  
Early Summer ◽  
Coelomic Fluid ◽  
Spawning Behaviour ◽  
Perinereis Nuntia

Perinereis nuntia brevicirrus (Grube 1857), collected from a rocky shore at Qingdao (China) were cultured under different temperature, daylength and moonlight regimes. Ripe individuals were found in the field after an increase of water temperature in early summer, with a semilunar spawning peak from the beginning of June to the end of September. In laboratory experiments, daylength has no influence on maturation and reproduction. Temperature-controlled culture produces gravid, reproducing specimens at any time of the year after an increase in water temperature. For reproduction both sexual partners leave their burrows and swarm at the water surface in the early morning, performing a nuptial dance. The spawning behaviour, the nuptial dance and the release of gametes, are controlled by sex pheromones which are present in the coelomic fluid of mature worms. A sex pheromone from Platynereis dumerilü, 5-methyl-3-heptanone, is found in Perinereis nuntia brevicirrus and causes an increase in swimming activity during reproduction and the release of a small amount of sperm from males. This signal induces the release of eggs by the females followed by the release of masses of sperm by the male due to a second female pheromone.

Effect of water temperature and light intensity on swim bladder inflation and growth of red sea bream Pagrus major larvae

2018 ◽  
Vol 84 (3) ◽  
pp. 553-562 ◽  
Author(s):  
Tomoki Honryo ◽  
Michio Kurata ◽  
Dario Sandval ◽  
Saki Yamao ◽  
Amado Cano ◽  
...  
Keyword(s):  
Light Intensity ◽  
Water Temperature ◽  
Red Sea ◽  
Sea Bream ◽  
Swim Bladder ◽  
Red Sea Bream ◽  
Pagrus Major ◽  
Effect Of Water ◽  
Swim Bladder Inflation

The reproductive cycle of the firetail gudgeon, Hypseleotris galii II. Seasonal histological changes in the testes

1973 ◽  
Vol 21 (1) ◽  
pp. 67 ◽  
Author(s):  
NJ Mackay
Keyword(s):  
Water Temperature ◽  
Breeding Season ◽  
Reproductive Cycle ◽  
Meiotic Division ◽  
Steroid Biosynthesis ◽  
Histological Changes ◽  
Late Autumn

Seasonal histological changes in the testis of H.galii are described. Spermatogenesis follows the cystic pattern common in anamniotes. Mitotic increase in spermatogonia occurs in late autumn, when photoperiod and water temperature are falling. The meiotic division of spermatocytes and subsequent changes of spermatogenesis are initiated when photoperiod and water temperature are rising and continue through the breeding season (November-January) until March, when water temperature begins to fall rapidly. The possible role of cholesterol-positive lobule boundary cells in steroid biosynthesis is discussed.

Persistent, vertical-migration rhythms in benthic microflora.: II. Field and Laboratory Studies On Diatoms From The Banks Of The River Avon

1966 ◽  
Vol 46 (1) ◽  
pp. 191-214 ◽  
Author(s):  
F. E. Round ◽  
J. D. Palmer
Keyword(s):  
High Temperatures ◽  
Vertical Migration ◽  
Laboratory Experiments ◽  
Biological Clock ◽  
Diatom Species ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Constant Illumination ◽  
Different Temperatures ◽  
Clock Hypothesis

The vertical migration of two Euglena species and several diatom species into and out of the sediment on the banks of the River Avon has been studied under natural conditions. All species have been shown to migrate vertically upwards when exposed during daylight. Tidal flooding of the sediment is generally preceded by re-burrowing of the algae beneath the surface. Methods have been devised to follow these migrations in both the field and laboratory. Laboratory experiments show that these migrations are rhythmic, continuing under constant illumination and temperature and removed from tidal influence. The effect of three different temperatures and three different light intensities has been investigated. Transfer from low to high temperatures has been shown to reset the phase of the rhythm. The results are discussed in relation to other work and to the ‘biological clock’ hypothesis.

Sign in / Sign up

Export Citation Format

Share Document