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1.
A major recruitment of the forcipulate asteroid Pisaster ochraceus was observed in September 1987 in the channel leading into Boca del Infierno, a semi-enclosed bay on the southeastern shore of Nootka Island, on the west coast of Vancouver Island, British Columbia, Canada. Newly settled recruits were observed at high densities subtidally in the channel (mean maximal density=1.23x104m-2) and at nearby sites. Subsequent surveys in 1988 to 1991 and size-frequency distributions of adults indicated strong yearly recruitment of P. ochraceus. Recruits of P. ochraceus were found on all available substrata, including hard and soft bottoms and on benthic algae. The initial food of the recruits included newly settled mussels (Mytilus sp.), snails and barnacles. Recruitment of the forcipulate Pycnopodia helianthoides was observed in 1987 to 1989 and in 1991, while recruitment of the spinulosan Dermasterias imbricata occurred only in 1988. High densities of planktonic bipinnaria larvae were found in the bay of Boca del Infierno in late May. We hypothesise that the high density population of adult P. ochraceus found in the channel of Boca del Infierno spawns synchronously and most of the resulting embryos and larvae are retained within the bay. This area may act as a source of larvae that then disperse locally. Post-recruitment mortality was estimated by comparing the density of recruits of P. ochraceus in 1987 with the numbers of juveniles presumed to be 1 yr old in 1988. Post-recruitment mortality was in excess of 97% with few individuals surviving to 1 yr. Moreover, even after the first year, mortality or emigration of the juveniles resulted in the almost complete loss of the 1-yr cohort at North Saavedra between 1988 and 1989. This study provides evidence that the P. ochraceus population in this area of Nootka Island may not be open, but may be regularly supplied from a source of larvae in the bay of Boca del Infierno. Post-settlement processes may, however, have significant effects on the local population, resulting in a poor correlation between the rate of recruitment and the incorporation of yr-1 + individuals into the adult population. 相似文献
2.
The ascidian Styela clava, native to the north-west Pacific, is an invasive species affecting New Zealand’s marine ecosystems, biodiversity and aquaculture
operations. To provide detailed information on the reproductive biology of S. clava in New Zealand for post-border biosecurity management, long-term seasonal patterns of gametogenesis were determined from
May 2006 to May 2008 in Auckland’s Waitemata Harbour (36°49′20″S, 174°45′85″E). Of particular interest was whether the critical
15°C threshold spawning temperature for reproduction observed in the Northern Hemisphere applied here to the first Southern
Hemisphere study. S. clava gametogenesis followed a regular seasonal cycle with ripe gametes appearing as early as September and persisting to June;
this time frame corresponds to the period when sea surface temperatures in the region first reach 15°C and with spawning occurring
mainly during late summer to early autumn. From photoperiod manipulation, it was determined that spawning occurred at approximately
18:20. The extended reproductive period and a short generation time in the Waitemata Harbour provides a lengthy opportunity
for S. clava to spread. Findings are discussed in relation to S. clava’s post-border management. 相似文献
3.
Sung-Geun Woo Holly L. Sewell Craig S. Criddle 《Frontiers of Environmental Science & Engineering》2022,16(10):127
4.
The pelagic yellowtail kingfish Seriola lalandi has become a target species for aquaculture in Asia and Australasia. Australasian production is reliant on larviculture from
eggs of captive brood stock; however, knowledge regarding the nutritional requirements of larvae of this species is still
scarce, particularly in relation to lipids. As a first step in establishing these requirements, eggs and larvae from captive
S. lalandi brood stock were examined for differences in total protein, total lipid and lipid classes between individual spawning events,
over the spawning season, and during larval development from fertilisation to 15 days post hatch. Results indicate that total
protein egg−1 varied significantly between individual spawning events within a season, but neither total lipid nor total protein egg−1 varied significantly across the spawning season. Brood stock egg lipids were made up of approximately 60% phospholipid, 25%
wax and/or sterol esters (WE), 15% triacylglycerol (TAG), and small amounts of sterols and free fatty acids. During the early
larval period, both WE and TAG were utilised concurrently for energy. The larvae experienced very high mortality around 5–7 days
post hatch, which coincided with very low levels of all neutral lipid classes. Although many other factors may also influence
larval mortality, these results indicate that lipid provisioning may be an important factor in larval survival during the
critical period around first-feeding in this species. Examination of ratios of TAG:ST, often used as a condition index in
fish larvae, suggested that some of the larvae were suffering from starvation. However, as egg-derived WE appears to provide
a significant source of energy during the early larval period in S. lalandi, it is suggested that WE should be included in any index of larval nutritional state. 相似文献
5.
The second prenatal diagnosis of galactosialidosis is reported. Neuraminidase and β-galactosidase activities in cultured amniotic cells were deficient, this being confirmed by skin fibroblast enzyme assay on the affected fetus after interruption of the pregnancy. Cultured placental cells demonstrated the same enzyme deficiencies. Analysis of deproteinized amniotic fluid showed the presence of abnormal oligosaccharides specific for a-neuraminidase deficiency. 相似文献
6.
For marine invertebrates, larval developmental mode is inseparably linked to the nutritional content of the egg. Within the
asterinid family of sea stars there have been multiple, independent, evolutionary transitions to lecithotrophic development
from the ancestral, planktotrophic state. To investigate the evolution of maternal investment and development within the Asterinidae,
we quantified individual lipid classes and total protein for eggs and larval stages of closely related species representing
three developmental modes (planktotrophy, planktonic lecithotrophy and benthic lecithotrophy). Within species, maternal provisioning
differed between females indicating that egg quality varied with parentage. Maternal investment was related to egg size but,
after correcting for egg volume, we identified two major oogenic modifications associated with the evolution of lecithotrophic
development: (1) a reduction in protein deposition that probably reflects the reduced structural requirements of nonfeeding
larvae, (2) an increase in deposition of a single class of energetic lipid, triglyceride (TG). The exception was Parvulastra exigua, which has benthic, lecithotrophic development and lays eggs with a lipid to protein ratio close to that of planktotrophs.
This oogenic strategy may provide P. exigua larvae with a protein “weight-belt” that assists in maintaining a benthic existence. Asterinids with planktotrophic development
used a significant portion of egg TG to build a feeding bipinnaria larva. For Meridiastra mortenseni, female-specific differences in egg TG were still evident at the bipinnaria stage indicating that egg quality has flow-on
effects for larval fitness. In lecithotrophic asterinids, TG reserves were not depleted in development to the larval stage
whereas protein stores may help fuel early larval development. Available data indicate that there may be two evolutionarily
stable egg lipid profiles for free-spawning, temperate echinoderms. 相似文献
7.
M. Byrne T. A. A. Prowse M. A. Sewell S. Dworjanyn J. E. Williamson D. Vaïtilingon 《Marine Biology》2008,155(5):473-482
Lipid and protein biochemistry of eggs (84 μm in diameter), embryos and early larvae of the tropical echinoid Tripneustes gratilla (Linnaeus 1758) were quantified to determine how maternal provisions are used to fuel development of the echinopluteus. The
eggs contained a mean of 30.82 ng lipid and 87.32 ng protein. Energetic lipids were the major lipid component (55.52% of total
lipid) with the major class being triglyceride (TG: mean 15.9 ng, 51.58% of total). Structural lipid was dominated by phospholipid
(PL: mean 11.18 ng, 36.26% of total). Early embryogenesis was not a major drain on egg energetic lipid and protein. Development
of the functional feeding larva used ca. 50% of initial egg energetic lipid and most of this was TG. Maternal TG was still
present in the 8-day echinoplutei and it was estimated that this energetic lipid would be depleted in unfed larvae by day
10. There was no change in PL. In a separate experiment lipid biochemistry of rudiment stage larvae and early developing juveniles
were quantified to determine how lipids are used during metamorphosis. Fed larvae accumulated lipid (mean 275.49 ng) with
TG and PL being the major energetic and structural lipids, respectively. Larval lipid stores were not appreciably depleted
by metamorphosis and so were available for the early benthic stage juvenile. Juveniles started their benthic existence with
314 ng total lipid (TG: mean 46.84 ng, 14.9% of total, PL: mean 137.51 ng, 43.67% of total). Nile Red histochemistry and histology
showed that the stomach serves as a nutrient storage organ and, that lipid stores accrued by larvae sustain developing juveniles
for up to 4 days post settlement. Triglyceride supported both non-feeding stages of development and the prefeeding larval
and perimetamorphic benthic stage. In this first study of lipid stores in settlement stage echinoderm larvae, we show that
T. gratilla larvae sequester the same major energetic lipid (TG) to support the early juvenile that the female parent provided them to
fuel early development. 相似文献
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10.
W. R. Derrick Sewell Lorna R. Barr 《Journal of the American Water Resources Association》1978,14(2):337-348
ABSTRACT: Water management in England and Wales has undergone a major transformation in the past three decades, and especially under the 1963 and 1973 legislation. It has witnessed a shift from local to national responsibility, an integration of functions, and a move towards the incorporation of economic principles into water policies. For some observers the new legislation appeared to be “pioneering” and “farsighted.” There is little doubt it has resulted in many beneficial changes. But not all the goals have been achieved. Modifications of the 1973 legislation are already in prospect. This article reviews the progress to date and comments on the problems now to be faced. 相似文献