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1.
Summary Morphological, histological and behavioral features indicate thatMycedium elephantotus, a zooxanthellate scleractinian species without tentacles, is well adapted for utilizing suspended organic matter for nutrition.
The colonies are composed of vertically growing fan-like plates and can reach diameters of more than 1 m in depths below 20
m. The external body surface is coated with a mucus layer (cuticle) which enables the acquisition and accumulation of suspended
organic material. The mucus-entangled particles pass to the mouth openings by gravitational transport assisted by water movement.
In experiments the corals were able to discriminate between suspended food and mineral particles. Both types of particles
were rapidly entangled in fine mucus nets or filaments. Mineral particles were never ingested and instead tumbled down the
inclined skeletal plates. In contrast, food particles were actively incorporated when the mucus filaments accidentally touched
the stomodaea during the downward gliding.
The food-enriched mucus filaments were either transported by ciliary activity into the coelenteron or were sucked into the
body cavities by decreasing pressure in the coelenteron caused by contraction of longitudinal, mesenterial muscles. The discriminative
reactions to mineral or food particles are probably based on the release of different types of mucus.
Nematocysts are infrequent in the oral epidermis, indicating that the capture of living prey plays a subordinate role in nutrition.
The mesenterial filaments, in contrast, are densely packed with large nematocysts. Storage products were piled up within the
tissues of gastral pockets.
The adaptations ofMycedium elephantotus for using suspended food particles may explain the particularly high abundance of this species between ca. 20 and 40 m depth
on a steeply inclined fore-reef slope in the Gulf of Aqaba (Red Sea).
The evidence indicating the importance of heterotrophic fueling toM. elephantotus is supported by carbonate production rates which are, in contrast to that of many other zooxanthellate scleractinian species,
almost constant at depths between 5 and 40 m and which are uneffected by varying light regimes over the year, suggesting that
the reduced phototrophic contribution by the zooxanthellae is compensated by mucus suspension feeding. 相似文献
2.
The unattached form ofLaminaria gurjanovae A. Zin. inhabiting silty and sandy bottoms at depths of 10–30 m in the area of the Tumen River mouth (Pos’eta Bay) is described
for the first time. Laminarian thalli interlace their long (up to 50-cm) stipes and form dense aggretations. 相似文献
3.
Summary This is the first study based on numerical analysis of the abundance of 11 scleractinian corals of depths at between 100–210 m in the Red Sea twilight zone. Two distinct coral communities were found: a Leptoseris fragilis community at a depth of 100–130 m (zone 1) and a Dendrophillia horsti community below 130 m (zone 2, 3). Population densities and coral coverage are very low; distribution of individuals is highly clumped. Highest observed densities on 100 m2 were 2720 individuals for L. fraglis, 2720 for D. horsti and 2260 for Javania insignis. Calculated coverage rates were maximally 3.6% (L. fragilis), 0.08% (D. horsti) and 0.11% (J. insignis). L. fragilis, the only symbiont bearing coral, was very abundant. It has an unusual depth range for a photosynthesising coral. Coral density is only weakly correlated with hard bottom coverage. Species diversity with an average of 8 species is highest at 120–170 m and decreases in shallower and deeper water. The study depth range is a transient zone for coral distribution. It contains the upper distribution limits of a few deep sea corals and the lower ones of several shallower water species. Ahermatypic corals, collected at 160–170 m depth, were transplanted from their original depth to 159, 118, 70 and 40 m; after one year most species survived transplantation far beyond their upper distributional limits. The symbiotic L. fragilis, collected at 120 m, survived transplantation to deep water (159 m) as well as shallow zones (90, 70 and 40 m). The study demonstrates the feasibility of line-transect methods for coral community studies with a submersible. 相似文献
4.
Ronald Fricke 《Ichthyological Research》1990,36(4):404-409
Psychrolutes occidentalis, a new species of psychrolutid fish, is described from mud bottoms at depths of 350–740 m on the continental slopes around
Rowley Shoals, northwestern Australia. The new species is illustrated and compared with other species of the genusPsychrolutes. It differs from other species in the following characters: 14–15 dorsal soft rays, 21–23 pectoral rays, 30–31 vertebrae,
no cirri on head and body, lateral line not emerging through tubes, and reddish brown head and body color with darker brown
marblings. Aspects of the zoogeography of this new species from the tropical region and of the other species ofPsychrolutes are discussed. 相似文献
5.
To clarify the ecological significance of the association of sulfate-reducing bacteria (SRB) with sediment particle size,
SRB utilizing lactate (l-SRB), propionate (p-SRB) and acetate (a-SRB) were examined with different sizes of sediment particles in a hypertrophic freshwater lake using the anaerobic plate
count method. The numbers ofl-SRB anda-SRB were 104–105 colony forming units (CFU) per ml in the 0–3 cm layer and 102–103 CFU ml−1 in the 10–13 cm layer while the numbers ofp-SRB were one or two orders lower than those ofl-SRB anda-SRB. A sediment suspension was fractionated into four fractions (<1, 1–10, 10–94 and >94 μm). The highest proportions ofl-SRB anda-SRB were found in the 10–94 μm fraction: 66–97% forl-SRB and 53–98% fora-SRB. The highest proportion ofp-SRB was found in the >94 μm fraction (70–74%). These results indicate that most SRB were associated with sediment particles.
One isolate from an acetate-utilizing enrichment culture was similar toDesulfotomaculum acetoxidans, a spore-forming sulfate-reducing bacterium. When lactate and sulfate were added to sediment samples,l-SRB anda-SRB in the <10 μm-fraction grew more rapidly than those in whole sediment for the first 2 days. This result suggests that
nutrients uptake by free-living and small particle-associated (<10 μm) SRB is higher than that by SRB associated with larger
particles. 相似文献
6.
Verification of daily growth increment formation in saury otoliths by rearing larvae from hatching 总被引:1,自引:0,他引:1
Naturally spawned eggs of the Pacific saury,Cololabis saira, were collected in the field and reared in a tank to examine daily periodicity of growth increment formation in the otolith.
Larvae were 6.9 mm in knob length at hatching. Their otoliths (sagittae) were 31 μm in radius and had 3–6 faint concentric
rings. They started feeding within two days and grew at a rate of 1.1 mm/day on average through larval and juvenile stages
feeding on rotifers,Artemia nauplii, and artificial diets. Otolith growth increments showed a concentric pattern with a distance of 3.5–5.0 μm between
two adjacent increments. The number of growth increments was almost equal to a known age in days plus 4 or 5. A regression
line of number of increments (N) on known age in days (D) between 0–30 days after hatching was N = 4.81 + 1.01D, which shows
that one increment was deposited per day. 相似文献
7.
Single-copy DNA-DNA hybridizations among five species ofLaminaria (Phaeophyceae): Phylogenetic and biogeographic implications 总被引:1,自引:0,他引:1
W. T. Stam P. V. M. Bot S. A. Boele-Bos J. M. van Rooij C. van den Hoek 《Helgoland Marine Research》1988,42(2):251-267
DNA-DNA hybridizations between single-copy nuclear DNA fromLaminaria digitata and total DNA fromL. saccharina, L. Hyperborea, L. rodriguezii, L. ochroleuca andChorda filum, respectively, show that these species ofLaminaria are genotypically closely related.Chorda filum is only distantly related withL. digitata. Based on the thermal elution patterns of the DNA hybrids, as quantified by ΔTm(e) values, it is hypothesized that all five species ofLaminaria evolved at about the same time from their most recent common ancestor some 15–19 Ma ago. This phylogenetic hypothesis is
discussed in relation to the history of modern laminarialean distribution patterns.
Paper presented at the XIV International Botanical Congress (Berlin, 24 July–1 August, 1987), Symposium 6-15, “Biogeography
of marine benthic algae”. 相似文献
8.
Hiroshi Kohno Riza Ordonio-Aguilar Atsushi Ohno Yasuhiko Taki 《Ichthyological Research》1996,43(1):1-9
The osteological development of the feeding apparatus was examined in early stage larvae of laboratory-reared seabass,Lates calcarifer. At initial mouth openings 40 hours after hatching, the larvae were equipped with the fundamental elements forming the oral
cavity, such as the trabecular roof, the lower branchial and hyoid arches forming the floor, the quadrate and symplectic-hyomandibular
cartilages making up the sides, and the maxilla and Meckel's cartilage bordering the jaws. The cleithrum appeared almost simultaneously.
The mechanics of creating a negative pressure in the oral cavity, which results in a “sucking” mode of feeding, were elucidated
from these elements. During a period from 50–60 to 100–110 hours after initial mouth opening (HAMO), new elements such as
the premaxilla and jaw teeth appeared, and the ossification of existing elements started. The new elements apparently enabled
the larvae to “grasp” food organisms, in addition to the already existing and increasing sucking ability, from 100–110 HAMO. 相似文献
9.
C. G. Messing D. L. Meyer U. E. Siebeck L. S. Jermiin D. I. Vaney G. W. Rouse 《Coral reefs (Online)》2006,25(1):164-168
A recent preliminary survey revealed that 12 species of unstalked crinoids occur on a gentle sandy slope (12–18 m depth) at Lizard Island, Great Barrier Reef, Australia; five of which are also found on coral reefs. The other seven appear to constitute a unique assemblage restricted to unconsolidated substrates, where most cling to algae or hide beneath rubble or sponges. Members of this assemblage exhibit all of the basic feeding postures found among reef-dwelling species. However, Comatula rotalaria, which lacks anchoring cirri and bears uniquely differentiated short and long arms, exhibits a posture different from other living crinoids. Quantitative transects reveal apparent depth-related differences in species composition: C. rotalaria dominated the 12 transects in 12–13 m (84% of 82 specimens), while Comatella nigra, Comatula cf. purpurea, Amphimetra cf. tessellata and Zygometra microdiscus accounted for 96% of 54 specimens observed along 12 transects in 16–17 m. 相似文献
10.
Polygordius antarcticus sp. nov. is described from benthic material collected at depths ranging between 31 and 61 m in Terra Nova Bay, Ross Sea,
during the 1987–1988 and 1988–1989 expeditions of the Italian National Research Program in Antarctica. This is the first named
species of the genus from Antarctic waters. Although no fully mature specimens were available, the new species appears unique
in combining the following features: a regular pygidium, inflated and with a single ring of round adhesive pads, a conical
prostomium with short antennae (only half as long as the prostomium) and shallow head fold, and a well-developed circulatory
apparatus, with circumoesophageal commissures entering the prostomium and long intersegmental commissures insinuating into
the ventrolateral compartments of the trunk. These and other significant features were investigated by light and scanning
electron microscopy. In the construction of the head and the scheme of the blood system, the new species resembles Polygordius triestinus Woltereck, described by Hempelmann in 1906, an aberrant species inhabiting muddy, anoxic sediments in the Adriatic Sea, but
it differs significantly from it in the shape of the mouth (in P. triestinus the upper lip is hypertrophied and strongly protruding) and the pygidium (in P. triestinus this region is stump-like and non-adhesive). The pygidium of P. antarcticus sp. nov. is encircled by 28–30 small adhesive pads, each with 15–20 glandular openings. Preterminal cirri are lacking, as
are perianal appendages. The anus is surrounded by six to seven lobes of which the midventral is largest and longest. A world
distribution map of the genus is provided.
Accepted: 27 August 1998 相似文献
11.
Variability of nutrients and phytoplankton biomass in a shallow brackish water ecosystem (Chilika Lagoon, India) 总被引:1,自引:0,他引:1
Satya Panigrahi Johan Wikner R. C. Panigrahy K. K. Satapathy B. C. Acharya 《Limnology》2009,10(2):73-85
Seasonal and spatial variations in water quality parameters, such as nutrients [NH4
+–N, NO2−–N, NO3−–N, PO43−–P, total nitrogen (TN) and total phosphorus (TP)], Secchi disc depth, salinity, dissolved oxygen, chlorophyll a, primary productivity and phytoplankton standing stock, were studied in Chilika Lagoon (from 27 sampling locations) during
2001–2003 to assess the present ecological status. The study was undertaken after a major hydrological intervention in September
2000, which connected the lagoon body and the Bay of Bengal via a manmade opening (new mouth). Current and old data on water
quality were also compared to establish the changes that had occurred after the hydrological intervention. Multivariate techniques
and gridding methods were used to investigate the spatial and seasonal variability of the data and to characterize the trophic
evolution of the basin. Results of principal component analysis (PCA) indicated that the 27 stations can be classified into
five groups based on similarities in the temporal variation of nutrients, chlorophyll a concentration, salinity, and other physicochemical parameters. The tributaries and the exchange of lagoon water with the
Bay of Bengal most probably determine the water quality and the dynamics of the ecosystem. Hydrodynamics of the lagoon, weed
coverage, input of urban sewage through tributaries and agricultural runoff are probably the key factors controlling the trophic
conditions of the lagoon. An increase in salinity and total phosphorus was noted after the new mouth was opened, while the
total suspended sediment load, the water column depth, and nitrogenous nutrients decreased. The new mouth opening also brought
changes in the phytoplankton species composition. 相似文献
12.
Robert Andrew King Sarah L. Harris Angela Karp Jacqueline H. A. Barker 《Tree Genetics & Genomes》2010,6(2):247-258
We present nine polymorphic di- and tri-nucleotide repeat nuclear microsatellite markers selected specifically for their use
in high throughput studies concerning the dioecious allotetraploid Salix alba–Salix fragilis willow complex. These taxa and their hybrids are difficult to discriminate using morphological characters. Thus, multiplex
reactions were developed for these microsatellite loci and their effectiveness to distinguish individuals, especially hybrids,
and their inheritance patterns in controlled crosses were determined. All loci displayed disomic–monogenic inheritance which
allowed for the genotype data to be analysed as for a diploid organism. The nine loci produced a total of 67 alleles (mean,
7.4 alleles per locus; range, 3–11 alleles) in a reference panel of 57 individuals from two germplasm collections and natural
populations. Gene diversity values (as measured by the expected heterozygosity) ranged from 0.000–0.820. A total of 53 distinct
multilocus genotypes were observed, and ordination analysis revealed three separate clusters corresponding to S. alba, S. fragilis and hybrids. The microsatellite loci described here will be used in population genetic studies to investigate genetic variation,
gene flow, levels of hybridisation and the extent of introgression in natural populations of the S. alba–S. fragilis complex. They are also useful for clonal identification, conservation and sustainable management of germplasm collections,
genetic mapping and the selection of individuals and/or certification of controlled crosses for breeding programmes. 相似文献
13.
Symphurus hondoensis Hubbs, 1915, originally described only from the holotype taken in 390–542 m in Suruga Bay Japan, has long been considered
a junior synonym ofS. strictus Gilbert, 1905, known from waters off Hawaii, Japan, the Philippine Islands, and South Africa. Based on new information from
the holotype and a specimen recently captured from deep waters (789–815 m) off Amami-Oshima Island, southern Japan,S. hondoensis is now established as a valid species.Symphurus hondoensis is unique among congeners in having the combination of a 1–2–3 pattern of interdigitation of proximal dorsal pterygiophores
and neural spines, 10 abdominal vertebrae, 14 caudalfin rays, 111–113 dorsal-fin rays, 95 anal-fin rays, 59 total vertebrae,
105–106 scales in longitudinal series, blind side nearly as darkly pigmented as the ocular surface, and a black peritoneum.
Recognition ofS. hondoensis increases the number of described species ofSymphurus in waters off Japan to three (S. orientalis Bleeker,S. strictus, andS. hondoensis), with at least one more underscribed species occurring in deepwater hydrothermal vent areas off southern Japan. 相似文献
14.
Rubén J. Lara Sucharit B. Neogi Mohammad S. Islam Zahid H. Mahmud Shafiqul Islam Debasish Paul Biniam B. Demoz Shinji Yamasaki Gopinath B. Nair Gerhard Kattner 《Wetlands Ecology and Management》2011,19(1):109-119
Wetland dynamics are probably linked to cholera endemicity in South Asia. We focus on links between Vibrio cholerae abundance, chitin content and suspended particle load in size fractions of suspended particulate matter (SPM) along the salinity
gradient of Sunderban mangrove waters. SPM decreased downstream, while salinity increased from 0.2 to 4. Particulate organic
carbon (90 ± 25 μM) and nitrogen (9.1 ± 3.3 μM) highly correlated with SPM and turbidity, suggesting a significant contribution
of fine particles to organic matter. Total chitin ranged 1–2 mg/l and decreased downstream. The distribution among size fractions
of SPM, chitin and V. cholerae O1 (the bacterial serogroup mainly associated with cholera epidemics) was similar, with ~98% of the total in the fraction
<20 μm. In comparison, the number of V. cholerae O1 attached to zooplankton and microplankton size classes >20 μm was almost negligible, in contrast to usual assumptions.
Thus, microdetritus, nanoplankton and fungal cells in size classes <20 μm represent a chitinaceous substrate on which V. cholerae can grow and survive. Total bacteria, cultivable vibrios and V. cholera O1 increased 5–10 times downstream, together with salinity and nitrite concentration. Overall, nitrate and silicate concentrations
were relatively constant (>22 μM N and 100 μM Si). However, nitrite increased ~9 times in the outer sector, reaching ~1.2 μM
N, probably as a result of increased abundance of nitrate-reducing vibrios. A characterization of Vibrio habitats that takes account of the presence of nitrate-reducing bacteria could improve the understanding of both mangrove
nitrogen cycling and cholera seasonality. 相似文献
15.
We assessed feeding and masticatory function in western tarsiers, Tarsius bancanus,from field study, from videotaped recordings of the feeding and chewing behavior of wild-caught animals in temporary captivity,
from dissections of the muscles of mastication, and from scanning electron microscopic (SEM) examination of wear features
of the teeth. Ingestion of large items of animal prey is made possible by the animal’s extremely wide gape. Anterior translation
of the knob-like mandibular condyle in the anteroposteriorly elongated mandibular fossa makes possible a gape angle of 60–70‡.
We observed two means of ingestion of grasshopper prey: ingestion by mastication, in which the postcanine teeth sever and
reduce bites of the food as it is thrust into the mouth cavity, and repeated gape-shove sequences, during which the tarsier
pushed grasshoppers of large diameter into the anterior part of its mouth and attempted to sever a bite with its anterior
teeth. Morsels were successfully severed after three to five such sequences, and reduced quickly,with relatively few powerful, crushing chews. The insect cuticle was not evenly comminuted during mastication. We observed
a marked side-to-side grinding component in the normal chewing cycle of T. bancanuson videotape and confirmed it by SEM. The main jaw adductors are bulky, long-fibered muscles that can accommodate wide grapes
and still generate, at wide degrees of gape,the high occlusal pressures necessary to fracture thick chitinous exoskeletons of the scarabid beetles that form a substantial
element of the western tarsier’s diet. 相似文献
16.
Bettina Saier 《Helgoland Marine Research》2000,54(4):224-229
On sedimentary tidal flats near the island of Sylt (German Bight, North Sea) abundance and size distribution of periwinkles, Littorina littorea L., were studied in low intertidal and in shallow and deep subtidal mussel beds (Mytilus edulis L.). In low intertidal mussel beds, surveys revealed that high densities (1,369±571 m–2) of juvenile snails (≤13 mm) were positively correlated with strong barnacle epigrowth (Semibalanus balanoides L. and Balanus crenatus Bruguière) on mussels. A subsequent field experiment showed that recruitment of L. littorea was restricted to the intertidal zone. Abundances of periwinkles (213±114 m–2) and barnacles abruptly decreased in the adjacent shallow subtidal zone, which served as a habitat for older snails (>13 mm). L. littorea was completely absent from disjunct deep (5 m) subtidal mussel beds. Snail abundance varied seasonally with maxima of >4,000 m–2 in low intertidal mussel beds in October and minima in July, just before the onset of new recruitment. I suggest that the
presence of cracks and crevices among the dense barnacle overgrowth in intertidal mussel beds favoured recruitment and survival
of juvenile snails. Larger (older) specimens are assumed to actively migrate to the less favourable adjacent subtidal. Therefore,
intertidal mussel beds are considered as nurseries for the population of L. littorea in the Wadden Sea.
Received in revised form: 25 September 2000
Electronic Publication 相似文献
17.
Bassobythites Brauer is a junior synonym ofLamprogrammus Alcock.L. macropterus Smith and Radcliffe is a junior synonym ofL. brunswigi Brauer.L. brunswigi is diagnosed by having: a basibranchial tooth patch; the postero-dorsal margin of the maxillary free or nearly so; a relatively
well-developed opercular spine in larger examples. Known distribution is circumtropical except for the eastern Pacific, at
trawled depths of 800–1600 m. 相似文献
18.
Morphological aspects of feeding and improvement in feeding ability in early stage larvae of the milkfish,Chanos chanos 总被引:1,自引:0,他引:1
Hiroshi Kohno Riza Ordonio-Aguilar Atsushi Ohno Yasuhiko Taki 《Ichthyological Research》1996,43(2):133-140
The osteological development of elements comprising the oral cavity and fins was examined in early stage larvae of laboratory-reared
milkfish,Chanos chanos, from hatching to 200 hours after hatching. Fundamental elements of the oral cavity had developed by the time of initial
mouth opening, 54 hours after hatching. The oral cavity was long and cylindrical, with a short, robust Meckel's cartilage,
and robust quadrate and symplectic-hyomandibular cartilages. The initial ossification of existing elements and addition of
new elements occurred between 120–146 hours after initial mouth opening (HAMO), whereas the cartilaginous basihyal and caudal
fin-supports appeared at 37.5 and 61.5 HAMO, respectively. Based on the morphology and developmental patterns of characters
examined in this study, the feeding mode of early stage larval milkfish was considered to be “straining,” with an improvement
in feeding ability occurring between 120–146 HAMO. 相似文献
19.
Larval mortality ofNeodiprion sertifer (Geoffroy),Diprion pini (L.) andGilpinia pallida (Klug) were studied in field experiments around a factory complex in southwestern Finland. Larval colonies were transferred
on the shoots of Scots pines growing at different distances from the emission source. Larval mortality was highest near the
factories. InN. sertifer, larval mortality caused by the nuclear polyhedrosis virus was higher and cocoon mortality caused by parasitoids was lower
near the pollutant source. The most abundant parasitoid species wereSynomelix scutulata (Hartig) andLamachus eques (Hartig). 16–67% of theN. sertifer, 0–5% of theD. pini and the 73–100% ofG. pallida cocoons contained parasitoids oviposited during the larval period of the sawflies.
相似文献
20.
The floristic composition, structure and dynamics of three primaryFagus japonica stands were investigated in the Chichibu Mountains.F. japonica was dominant [RD(%): 64.9–87.0] and showed a slightly inverse J-shaped DBH class distribution in the quadrats [No. of canopy
stems (H>20m): 87–138/ha]. The stems ofF. japonica for each size were distributed in the form of colonies, being scattered almost uniformly, and arranged in positive association
with each other. Detailed examination of the bases of the stem groups forming colonies revealed that most of them originated
from the bases of dead mother stems and that they were from common stools [No. of large stems (H>10 m) per stool: 6–11]. Among
six major canopy gaps observed, only one included stems sprouting from the outer part ofF. japonica stools, while all the others were occupied by individuals of species other thanF. japonica. After tree-fall, several undercanopyF. japonica stems remained. Thus canopy gaps in these forest stands recovered through the sprouting of remainingF. japonica stools or by new sprouting ofF. japonica individuals adjacent to the gaps. However, it was considered difficult to fill canopy gaps only with sprouts when the distance
between the center of a gap and that of a stool surpasses the crown vector. Such places that are not fully occupied by sprouts
will be filled by individuals of other canopy and/or under-canopy species. 相似文献