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1.
Sergio Rossi Josep-María Gili Rafel Coma Cristina Linares Andrea Gori Neus Vert 《Marine Biology》2006,149(3):643-651
Temporal variations in protein, carbohydrate, and lipid levels were studied in a passive suspension feeder, the gorgonian Paramuricea clavata. The samples were collected every month for mature and immature colonies over a three-year period (1997–2000). The relationship between biochemical composition and reproductive output was examined on the basis of the 1998 and 1999 data. In female and male P. clavata colonies, the tissue displayed differences in lipid concentrations only in winter–spring, due to the high lipid levels attained by female colonies in this period. Immature colonies showed significant differences in lipid concentration only with respect to mature females in spring. There were clear seasonal trends in the lipid and carbohydrate levels in P. clavata, with maximum values in winter–spring [male lipid 212±75 SD μg mg−1 of organic matter (OM) and female lipid 274±103 SD μg mg−1 of OM; male and female carbohydrate 68±14 SD μg mg−1 of OM], coinciding with maximum food concentration/quality, and minimum values in summer–autumn (male and female lipid 155±57 SD μg mg−1 of OM; male and female carbohydrate 56±14 SD μg mg−1 of OM), coinciding with low food concentration/quality. The relationship between reproductive output and tissue concentrations of lipids, carbohydrates, and proteins was not straightforward, although there was an evident overlap of the lipid accumulation and the gonadal development. The results of this study show that protein, carbohydrate, and lipid levels may provide a record of episodes in the ecological cycle bearing on the trophic aspects of the target species. The results indicate that information on seasonal biochemical levels may explain benthopelagic coupling processes, provided factors such as natural diet, feeding rates, reproduction, and growth are well understood. 相似文献
2.
During early development in fish, phospholipase A2 (EC 3.1.1.4) regulates membrane lipid modifications, which relates to changes in environmental conditions and provision of
fatty acids required for metabolic energy substrates and prostaglandin biosynthesis. A method to analyze phospholipase A2 in rat tissues has been modified to measure its activity in embryonic Atlantic halibut (Hippoglossus hippoglossus L.). Egg and embryo samples were collected during the 1994 spawning season. Enzyme activity was undetectable at fertilization
but in 10-d embryos was 230 pmol mg−1 h−1 (at 20 °C) and increased by ∼120% at hatch (17-d). Significant alterations in the fatty acid composition of important phospholipids,
phosphatidylcholine (PC) and phosphatidylethanolamine (PE), were also observed. The content of some critical polyunsaturated
fatty acids, and the ratio of unsaturated/saturated fatty acids, declined significantly over development. Acyl-chain restructuring
mediated through the activity of phospholipase A2, coupled with other observed lipid changes (significant increases in the PC/PE ratio and cholesterol content), would produce
a decreased fluidity of membranes during embryonic development, coinciding with the predicted upward movement of larvae in
the water column. Arachidonic acid (20:4n-6) removed from PE could serve as a precursor for biosynthesis of 2-series prostaglandins, and eicosapentaenoic acid (20:5n-3) from PC is a likely source for other prostaglandin types. Despite removal of polyunsaturated fatty acids, there was an
overall increase in lipid and fatty acid concentration, which can be attributed to amino acid catabolism during early developmental
stages.
Received: 9 September 1996 / Accepted: 8 September 1997 相似文献
3.
The relationship between intermoult duration (coloration), sex, size and seasonal variations in fatty acid (FA) profiles
was studied in a population of shore crabs, Carcinus maenas, inhabiting the Isefjord, Denmark. For male shore crabs, the total hepatopancreas FA content was high in July and December
(12.7 to 16.0 mg g−1 dry weight, dw) but lower in May and September (7.3 to 10.0 mg g−1). This indicates that male shore crabs are in relatively good condition before winter, when the crabs migrate off shore,
but in relatively poor condition when they return to shallow waters during spring. The hepatopancreas FA content also decreased
over the mating season. After the mating season the hepatopancreas FA content of males had decreased to approximately 60%
of that prior to the mating season. Female shore crabs had significantly higher hepatopancreas FA levels than males in May
(11.7 mg g−1 dw), September (12.6 mg g−1 dw) and December (17.9 mg g−1 dw) but lower levels in July (9.5 mg g−1 dw). This indicates that the spawning season is the most energy-demanding part of the female reproductive cycle. For all
seasons, the hepatopancreas FA content of green shore crabs was significantly higher than that of red shore crabs. For both
colour forms, the amount of polyunsaturated fatty acids (PUFAs) was significantly higher than that of saturated fatty acids
(SAFAs) and monounsaturated fatty acids (MUFAs), with the relative proportion of PUFAs increasing when the total hepatopancreas
FA content decreased. For both genders and colour forms, the most dominating SAFA was palmitic acid (16:0). Palmitoleic acid
(16:1ω7), vaccenic acid (18:1ω7) and oleic acid (18:1ω9) were the three MUFAs found in highest concentrations. The most dominating
PUFA was eicosapentaenoic acid (EPA, 20:5ω3). Docosahexaenoic acid (DHA, 22:6ω3) and arachidonic acid (AA, 20:4ω6) were also
abundant in all samples. The results demonstrated that season, sex, size and intermoult duration all influence the amount
of FAs present in the hepatopancreas of shore crabs.
Received: 23 September 1999 / Accepted: 29 April 2000 相似文献
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.
Females of the spionid polychaete Streblospio benedicti (Webster) produce either small eggs (60–70 μm diameter) and planktotrophic larvae, or large eggs (100–200 μm) and lecithotrophic larvae that reportedly do not feed. This intraspecific polymorphism, a form of poecilogony, is potentially useful in studies of larval ecology and evolution, but necessary data on larval form and function are lacking. This study describes the morphology and nutritional biology of larvae obtained from Atlantic (South Carolina) and Pacific (California and Washington) populations from 2003 to 2005. The two types of larvae produced by Atlantic S. benedicti differed greatly in length (229±22 μm SD for planktotrophs vs. 638±40 μm for lecithotrophs) and chaetiger number (2–5 vs. 10–11) at release from the female’s brood pouch. Planktotrophic larvae bore long provisional chaetae on their first chaetiger; provisional chaetae were absent in lecithotrophic larvae. Larvae from Pacific populations were all of the lecithotrophic form, and were similar to their Atlantic counterparts in all respects. High-speed video microscopy revealed that both types of larvae used opposed bands of cilia to capture suspended particles and transport them to the mouth, where they were often ingested. Lecithotrophic larvae reared with suspended phytoplankton (Rhodomonas sp., 104 cells ml−1) for 2 days grew significantly faster than sibling larvae reared without added food, indicating that these larvae can digest and assimilate ingested food. Larvae of S. benedicti that develop from large eggs are thus facultative planktotrophs instead of obligately non-feeding lecithotrophs, a result that affects the interpretation of comparative studies of the ecology and evolution of larvae in S. benedicti and certain other marine invertebrates. 相似文献
6.
Benjamin J. Laurel Louise A. Copeman Thomas P. Hurst Christopher C. Parrish 《Marine Biology》2010,157(8):1713-1724
The lipid/fatty acid composition of marine fish eggs and larvae is linked with buoyancy regulation, but our understanding
of such processes is largely restricted to species with pelagic eggs. In this study, we examined developmental changes in
the lipid/fatty acids of eggs and embryos of Pacific cod (Gadus macrocephalus), a species that spawns demersal eggs along coastal shelf edges, but as larvae must make a rapid transition to the upper
reaches of the water column. Adult Pacific cod were collected in the Gulf of Alaska during the spawning season and eggs of
two females were artificially fertilized with sperm from three males for each female. The eggs were subsequently reared in
the laboratory to determine (1) how lipids/fatty acids were catabolized during egg and larval development, and (2) whether
lipid/fatty acid catabolism had measurable effects on egg/embryo density. Eggs incubated at 4°C began hatching after 3-weeks
and continued to hatch over a 10-day period, during which there was a distinct shift in lipid classes (phospholipids (PL),
triacyglycerols (TAG), and sterols (ST)) and essential fatty acids (EFAs: 22:6n-3 (DHA), 20:5n-3 (EPA), and 20:4n-6 (AA)).
In the egg stage, total lipid content steadily decreased during the first 60% of development, but just prior to hatch we observed
an unexpected 2–3-fold lipid increase (~6–9 μg individual−1) and a significant drop in egg density. The increase in lipids was largely driven by PL, with evidence of long-chained fatty
acid synthesis. Late-hatching larvae had progressively decreasing lipid and fatty acid reserves, suggesting a shift from lipogenesis
to lipid catabolism with continued larval development. Egg density measures suggest that lipid/fatty acid composition is linked
to buoyancy regulation as larvae shift from a demersal to a pelagic existence following hatch. The biochemical pathway by
which Pacific cod are apparently able to synthesize EFAs is unknown, therefore representing a remarkable finding meriting
further investigation. 相似文献
7.
To investigate copepod nauplii ingestion rates on phytoplankton, we have adapted the traditional gut fluorescence technique
as it can be used with lower gut pigment concentrations. With the improved technique, laboratory experiments were performed
to estimate functional responses for nauplii of Calanus helgolandicus and Centropages typicus. Nauplii were raised from eggs to copepodites and the experiments were performed with stages NIV-NV. Gut evacuation rates
and ingestion rates were measured on Isochrysis galbana at different concentrations. Specific ingestion rates ranged between 0.038–0.244 μg C μg−1 nauplii C d−1 for C. typicus and 0.041–1.412 μg C μg−1 nauplii C d−1 for C. helgolandicus. Both species showed a type III functional response, reaching a saturation concentration at around 600 μgC l−1 for C. typicus and 800 μgC l−1 for C. helgolandicus.
An erratum to this article can be found at 相似文献
8.
Cadmium accumulation in the female shore crab Carcinus maenas during the moult cycle and ovarian maturation 总被引:2,自引:0,他引:2
The influence of moulting and ovarian maturation on cadmium accumulation in the tissues of female shore crabs Carcinus maenas exposed to 1 mg Cd l−1 in the water was investigated. Cadmium accumulation in all tissues examined was markedly increased in crabs in the postmoult
stages (A and B) compared to crabs in all other moult stages. During the moult cycle, average cadmium accumulation in the
midgut gland ranged from 29 μg Cd g−1 dw at premoult stage (D2) to 589 μg Cd g−1 dw at postmoult stage (A). Average cadmium concentrations in the haemolymph ranged from 0.56 μg Cd ml−1 at intermoult stage (C4) to 4.6 μg Cd ml−1 at postmoult stage (A), while the gills accumulated from 103 μg Cd g−1 dw in intermoult stage (C3) to 352 μg Cd g−1 dw in postmoult stage (A). Cadmium concentration in gills and haemolymph was also significantly higher in crabs in late premoult
stage (D3) compared to C4-crabs, while midgut gland cadmium concentration remained elevated in C1- and C3- intermoult stages relative to C4. During ovarian maturation the cadmium accumulation in midgut gland, gills, ovaries and haemolymph decreased. Average cadmium
concentration in the midgut gland decreased from 63 μg g−1 dw in ovarian Stage I to 19 μg g−1 dw in ovarian Stage VI. The same pattern was observed for gills, haemolymph and ovaries. The present study demonstrates that
cadmium accumulation in the female shore crab strongly depends on the physiological status of the animal. A possible association
between physiological calcium requirements and cadmium accumulation during moulting is discussed.
Received: 20 January 2000 / Accepted: 20 July 2000 相似文献
9.
John F. Barimo Joseph E. Serafy Peter E. Frezza Patrick J. Walsh 《Marine Biology》2007,150(3):497-508
Field studies were conducted in Johnson Key Basin, Florida Bay, USA from September 2002 through September 2004 to examine physiological, ecological, and behavioral characteristics of the gulf toadfish, Opsanus beta (Goode and Bean in Proc US Natl Mes 3:333–345, 1880), in relation to nitrogen metabolism, habitat usage, and spawning. Fish collected 5 cm above sediments in experimental shelters (epibenthic) were compared with those collected by throw traps which were found on or burrowing within sediments. The relationship between microhabitat ammonia and urea excretion, as determined by the enzymatic activity of glutamine synthetase (GS), was examined. The hypothesis tested was that O. beta occupying epibenthic nests were less ureotelic with lower GS activities than non-nesting individuals on/in sediments, due to a decreased environmental ammonia burden. Porewater total ammonia (T
Amm) concentrations at a sediment depth of 5 cm, i.e., the approximate depth of burrowing toadfish, ranged from 0 to 106.5 μmol N l−1 while the pH ranged from 7.48 to 9.14. There was a weak but significant correlation between environmental ammonia (NH3) concentration and hepatic GS activity for epibenthic toadfish (P < 0.001, r
2 = 0.10), but not for burrowing toadfish. Mean urea-N and T
Amm concentrations within shelters occupied by toadfish (n = 281) were 9.8 ± 0.83 μmol N l−1 and 13.0 ± 0.7 μmol N l−1, respectively. As predicted, hepatic GS activity was significantly lower in epibenthic toadfish captured in shelters (4.40 ± 0.24 μmol min−1 g−1; n = 281) as compared to individuals on/in sediments (6.61 ± 0.47 μmol min−1 g−1; n = 128). Glutamine synthetase activity generally peaked in March (spawning season) and was lowest in July. Gender differences in hepatic and branchial GS activity were also found during the spawning season, which is attributable to the fact that males brood and guard offspring in their epibenthic nests while females often rest on or burrow into the sediments. Finally, hepatic and branchial GS appeared to have different patterns of enzymatic activity suggesting functional differences in gene expression. 相似文献
10.
The marine copepod Calanus hyperboreus accumulates large quantities of lipids and essential fatty acids during summer months in Northern oceans. However, few data
exist regarding their winter fatty acid profiles, which could be informative regarding the use of lipids by C. hyperboreus to successfully survive and reproduce during times of ice-cover and limited food. The present study compared fatty acids
of C. hyperboreus between summer (August 2007 and 2008) and winter (early April 2008 and 2009) in Cumberland Sound, Canada. Summer samples
from both years had significantly higher ∑polyunsaturated fatty acids and unsaturation indices (based on μg fatty acid mg
dry tissue−1) than winter samples and separated on a principal component analysis due to higher 18:2n-6, 18:4n-3, and 20:5n-3, consistent
with phytoplankton consumption. Winter C. hyperboreus had significantly higher ∑monounsaturated fatty acids (MUFA) versus summer samples and separated on the principal component
analysis due to higher proportions of 16:1n-7, 20:1n-9, and 22:1n-9, suggesting they were not actively feeding. Based on the
seasonal fatty acid comparison, C. hyperboreus was catabolizing specific fatty acids (e.g. 20:5n-3), conserving others (e.g. 22:6n-3), and maintaining or increasing biosynthesis
of certain MUFA (e.g. 18:1n-9) during winter. These findings provide insight into the seasonal strategy of acquisition (summer)
and utilization (winter) of specific fatty acids by a key Arctic organism and could become important for monitoring changes
in fatty acids associated with decreased ice-cover duration due to climate warming. 相似文献
11.
A suite of characteristics is often used to assess egg quality as these properties potentially play important roles in progeny survival and growth. Our objective was to assess egg characteristics including lipid biocomposition of an iteroparous, batch-spawning teleost of wild origin. Maternal allocation to egg number was generally dome-shaped (5 of 8 females) and egg size declined over the breeding season for eight breeding pairs of wild Atlantic cod (Gadus morhua) (n = 43 batches). Egg lipid composition ranged considerably among females and between egg batches within females (e.g., phospholipids 40–86 %; polar 47–87 % and neutral lipids 15–52 % of total lipids; polyunsaturated fatty acids 16–50 % of total fatty acids). Principal component analyses revealed significant inter-relationships among maternal traits, batch sequence and fecundity, and egg size and composition. Seasonal trends with regard to lipid deposition were variable; three females showed consistent declines in lipid parameters (μg egg−1) with both batch number and egg diameter, one female showed consistent increase and the four remaining females showed no trend. The three females that exhibited seasonal declines in egg lipid content were characterized as having high fertilization success (>75 %). Our findings highlight the variability in lipid allocation to eggs of batch spawners of wild origin and characterize the composition of endogenous reserves available during embryogenesis and yolk sac larval stages. 相似文献
12.
Marja Koski 《Marine Biology》2007,151(5):1785-1798
Feeding, egg production, hatching success and early naupliar development of Calanus finmarchicus were measured in three north Norwegian fjords during a spring bloom dominated by diatoms and the haptophyte Phaeocystis pouchetii. Majority of the copepod diet consisted of diatoms, mainly Thalassiosira spp. and Chaetoceros spp., with clearance rates up to 10 ml ind−1 h−1 for individual algae species/groups. Egg production rates were high, ranging from ca 40 up to 90 eggs f−1 d−1, with a hatching success of 70–85%, and fast naupliar development through the first non-feeding stages. There was no correlation
between the egg or nauplii production and diatom abundance, but the hatching success was slightly negatively correlated with
diatom biomass. However, the overall high reproductive rates suggested that the main food items were not harmful for C. finmarchicus reproduction in the area, although direct chemical measurements were not conducted. The high population egg production (>1,20,000
eggs m−2 d−1) indicated that a large part of the annual reproduction took place during the investigation, which stresses the importance
of diatom-dominated spring phytoplankton bloom for population recruitment of C. finmarchicus in these northern ecosystems. 相似文献
13.
Katsutoshi Ito Mana Nozaki Takashi Ohta Chiemi Miura Yuzuru Tozawa Takeshi Miura 《Marine Biology》2011,158(6):1211-1221
Polychaetes constitute most of the benthic macroinvertebrates in estuarine and coastal environments. We investigated the utilization
of organic matter in two polychaete species, Capitella sp. I and Perinereis nuntia brevicirris, living in different coastal habitats. The protease activity of Capitella sp. I (89.7 μg mg−1) was about 10 times that of P. nuntia brevicirris (8.0 μg mg−1). High cellulase (endo-β-1,4-glucanase) activity was detected in P. nuntia brevicirris (3.2 μg mg−1), whereas scarcely any was detected in Capitella sp. I. We isolated cDNA clones of protease mRNA from Capitella sp. I and of cellulase mRNA from P. nuntia brevicirris. The high protease activity of Capitella sp. I enabled it to survive in the sediment under a fish farm, where it degrades organic matter. In contrast, the high cellulase
activity of the estuary-dwelling P. nuntia brevicirris allowed it to degrade organic matter originating from terrestrial areas. 相似文献
14.
Teresa Moura Carla Nunes Narcisa Bandarra Leonel Serrano Gordo Ivone Figueiredo 《Marine Biology》2011,158(2):401-412
The embryonic development and the level of dependency of the embryos from the maternal organism were investigated for Centroscymnus coelolepis. During the development, there is a 22–32% loss of organic matter and gains of 95–122% and 29–46% on moisture and inorganic
matter, respectively. Only 28–48% of the initial yolk energy is conserved in embryos, being the remaining used in catabolism.
In late pregnancy, the epithelium thickness of uterine villi decreases and vascularity increases. Results suggest that only
water and minerals are transferred from the mother to the embryos. Monounsaturated fatty acids are the main type of fatty
acids representing 48% of the total yolk fatty acid content, followed by polyunsaturated (30%) and saturated fatty acids (18–21%). 相似文献
15.
The maternal–embryo relationship was determined for the piked spurdog (Squalus megalops). In addition, the increase in offspring size with maternal size was studied and the embryonic development was described. Wet weight of in utero eggs and offspring size was correlated with maternal size; larger females produced larger embryos which would have higher survival rate and reproductive value. All embryos present in a female were at a similar stage of development. The external yolk sac is reabsorbed late in gestation, suggesting that embryos are mostly nourished by yolk sac reserves. Embryo size-at-birth varied considerably (180–244 mm total length) as a result of the significant variability in ova size at ovulation. The amounts of water, organic and inorganic matter of embryos at different stages of development were measured to determine possible maternal contributions during embryonic development. Total wet weight from smallest and largest in utero eggs to smallest and largest term embryos changed by +46 and +58%, respectively. This pattern was due to a change in water content by +137 and +154%, and inorganic matter by +100 and +156%. Organic matter of smallest and largest in utero eggs changed by −23 and −17%, respectively. The uterus of pregnant females became specialised for water and mineral transport, not nutrient provision. These results indicate that S. megalops is a strict yolk-sac viviparous species with no maternal contribution of organic matter during development. 相似文献
16.
A. Sakka Hlaili B. Grami Hassine Hadj Mabrouk M. Gosselin D. Hamel 《Marine Biology》2007,151(2):767-783
Phytoplankton growth and microzooplankton grazing were investigated in the restricted Bizerte Lagoon in 2002 and 2004. The
2002 study, carried out at one station from January to October, showed significant seasonal variations in phytoplankton dynamics.
High growth rates (0.9–1.04 day−1), chlorophyll a (Chl a) concentrations (6.6–6.8 μg l−1) and carbon biomass (392–398 μg C l−1) were recorded in summer (July), when several chain-forming diatoms had intensively proliferated and dominated the carbon
biomass (74%). In 2004, four stations were studied during July, a period also characterized by the high proliferation of several
diatoms that made up 70% of the algal carbon biomass. In 2004, growth rates (0.34–0.45 day−1) and biomass of algae (2.9–5.4 μg Chl a l−1 and 209–260 μg C l−1) were low, which may be related to the lower nutrient concentrations recorded in 2004. Microzooplankton >5 μm were mainly
composed of heterotrophic dinoflagellates and ciliates. Microzooplankton biomass peaked during summer (2002 320–329, 2004
246–361 μg C l−1), in response to the enhanced phytoplankton biomass and production. The grazer biomass was dominated by ciliates (71–76%)
in July 2002 and by heterotrophic dinoflagellates (52–67%) in July 2004. Throughout the year and at different stations, microzooplankton
grazed actively on phytoplankton, removing 26–58% of the Chl a and 57-84% of the primary production. In 2002, the highest grazing impact was observed on the large algae (>10 μm) during
the period of diatom dominance. These results have a significant implication for carbon export to depth. Indeed, the recycling
of most of the diatom production by the microbial food web in the upper water column would reduce the flux of material to
the seafloor. This should be considered when modeling the carbon cycling in coastal environments and under conditions of diatom
dominance. During both studies, ciliates had higher growth rates (0.5–1.5 day−1) and a higher carbon demand (165–470 μg C l−1 day−1) than dinoflagellates (0.1–0.5 day−1, 33–290 μg C l−1 day−1). Moreover, when grazer biomass was dominated by ciliates (in July 2002), herbivory accounted for 71–80% of the C ingested
by microzooplankton while it accounted only for 14–23% when dinoflagellates dominated the grazer biomass (in July 2004). These
results suggest that, in contrast to findings from open coastal waters, ciliate species of the restricted Bizerte Lagoon were
more vigorous grazers of the large algae (diatoms) than were dinoflagellates. 相似文献
17.
Seasonal lipid dynamics of various developmental stages were investigated in Pseudocalanus minutus and Oithona similis. For P. minutus, the dominance of 16:1(n−7), 16:4(n−3) and 20:5(n−3) fatty acids indicated a diatom-based nutrition in spring, whereas 22:6(n−3), 16:0, 18:2(n−6) and 18:1(n−9) pointed to a flagellate-based diet during the rest of the year as well as omnivorous/carnivorous low-level feeding during winter. The shorter-chain fatty alcohols 14:0 and 16:0 prevailed, also reflecting biosynthetic processes typical of omnivores or carnivores. Altogether, the lipid signatures characterized P. minutus as an opportunistic feeder. In contrast, O. similis had consistently high amounts of the 18:1(n−9) fatty acid in all stages and during all seasons pointing to a generally omnivorous/carnivorous/detritivorous diet. Furthermore, the fatty alcohol 20:1(n−9) reached high percentages especially in adult females and males, and feeding on Calanus faecal pellets is suggested. Fatty alcohols, as wax ester moieties, revealed significant seasonal variations in O. similis and a seasonal trend towards wax ester accumulation in autumn in P. minutus. P. minutus utilized its lipid deposits for development in the copepodite stages III and IV and for gonad maturation in CV and females during the dark season. However, CVs and females depended on the spring phytoplankton bloom for final maturation processes and reproduction. O. similis fueled gonad maturation and egg production for reproduction in June by wax esters, whereas reproduction in August/September co-occurred with the accumulation of new depot lipids. Both species revealed significantly higher wax ester levels in deeper (>50 m) as compared to surface (0–50 m) dwelling individuals related to a descent prior to overwintering. 相似文献
18.
The reproductive strategies of two gammaridean amphipod species, Gammarus wilkitzkii and Apherusa glacialis, that permanently inhabit the Arctic sea ice were investigated. G. wilkitzkii reaches sexual maturity at an age of 2 years and produces 128 ± 54 eggs fem.−1 yr−1. Mating takes place during fall and winter, and the development of the large eggs (0.60 to 0.80 mm diam.) lasts 6 to 7 months.
The sex ratio of G. wilkitzkii was dominated by males in a proportion of 1.5:1. In vivo studies showed that juveniles are released in batches from the brood
pouches of the females during April and May. A. glacialis reaches sexual maturity at the age of 1 year and produces 555 ± 151 eggs fem.−1 yr−1. The eggs are between 0.18 and 0.23 mm in diameter, and are the smallest known for gammaridean amphipods. Eggs are kept in
packages of two to eight in the brood pouches of females. The sex ratio of A. glacialis was dominated by females in a proportion of 3:1. The high fecundity of both amphipod species, the release of juveniles in
batches over a period of time, a high proportion of females (A. glacialis), and an elongated life-span with multiple spawnings (G. wilkitzkii) are discussed as possible adaptations to the specific and highly variable conditions under Arctic sea ice.
Received: 29 December 1999 / Accepted: 8 March 2000 相似文献
19.
Although mysids play important roles in marine food chains, studies on their production are scarce, especially for warm-water
species. We investigated life history and production of Orientomysis robusta in a shallow warm-temperate habitat of the Sea of Japan. Its spawning and recruitment occurred throughout the year; 19 overlapping
cohorts were recognizable over an annual cycle. The summer cohorts recruited in July–September exhibited rapid growth, early
maturity, small brood size, and small body size. A converse set of life history traits characterized the autumn–winter cohorts
recruited in October–March. The spring cohorts recruited in April–June had intermediate characteristics of both cohorts. Life
spans were 19–33, 21–48, and 69–138 days for summer, spring, and autumn–winter cohorts, respectively, and mortality rates
were high for spring and summer cohorts, especially during June–August but were low for autumn–winter cohorts. Production
calculated from the summation of growth increments was 488.8 mg DW m−2 year−1 with an annual P/B ratio of 21.26. The short life span seems to be responsible for such an extremely high P/B ratio. A method not requiring recognition and tracking cohorts gave similar values (534.0 mg DW m−2 year−1 and 20.49). The close agreement in production values between the two methods indicates our estimates are valid. 相似文献
20.
Ecological and physiological studies focused on dietary preferences, lipid biochemistry and energetics within the three Antarctic
chaetognaths Eukrohnia hamata, E. bathypelagica and E. bathyantarctica from meso- and bathypelagic depths. Eukrohnia hamata and E. bathypelagica respired 0.15 μL O2 mg dry mass (DM)−1 h−1, which translates to an average metabolic loss of only <1.1% of body carbon per day. Lipid storage was not substantial in
E. bathypelagica (mean 11.5 ± 6.5% DM) and E. bathyantarctica (mean 15.4 ± 4.1% DM) during summer and winter, suggesting year-round feeding of these predators mainly on copepods. In E. bathypelagica, total fatty acids were dominated by the fatty acids 16:0, 20:5(n-3) and 22:6(n-3) and in E. bathyantarctica also by 18:1(n-9), a fatty acid usually found in storage lipids. Only the latter species was characterized by significant
amounts of wax esters, consisting largely of the common fatty alcohols 16:0, 20:1(n-9) and the unusual fatty alcohol isomer
22:1(n-9). 相似文献