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1.
The marine diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana have been shown to produce apo-fucoxanthinoid compounds which act as feeding deterrents against the harpacticoid copepod Tigriopus californicus. The amounts and types of apo-fucoxanthinoids produced were species specific. Th. pseudonana produced small quantities of apo-12-fucoxanthinal and apo-13-fucoxanthinone only during senescence, while P. tricornutum produced much greater quantities of these two compounds during both log and senescence phases, in addition to producing a third compound, apo-10-fucoxanthinal, only during senescence. For both species, production of apo-fucoxanthinoids increased as the cells entered senescence phase due to phosphate limitation. The amounts of apo-fucoxanthinoids necessary to reduce feeding in T. californicus by 50% ranged from 2.22 to 20.2 ppm. This range was approximately 1000 times lower than the total apo-fucoxanthinoid concentration in P. tricornutum. The amounts of apo-fucoxanthinoids necessary to cause a 50% mortality in a population of T. californicus ranged from 36.8 to 76.7 ppm. Thus, these compounds are present in concentrations which may have ecological significance in the control of bloom formation and grazing. The production of apo-fucoxanthinoids may be a phenomenon common to many diatoms, particularly as they enter senescence due to nutrient limitation. 相似文献
2.
Methanol extracts of freshly harvested cells of the marine diatom Phaeodactylum tricornutum were found to produce a feeding deterrent effect in the copepod Tigriopus californicus. Bioassay guided fractionation of the methanol extracts led to the isolation of four compounds possessing feeding deterrent activity. The compounds were identified as apo-10-fucoxanthinal (1), apo-12-fucoxanthinal (2), apo-12-fucoxanthinal (3), and apo-13-fucoxanthinone (4) by detailed spectroscopic analysis and comparison with authentic compounds produced semi-synthetically from fucoxanthin. Compounds 1 to 4 exhibited feeding deterrent responses in T. californicus at concentrations of less than 20 ppm. 相似文献
3.
Marine phytoplankton have been shown to use chemical feeding deterrents to reduce or inhibit zooplankton grazing. In order to screen phytoplankton species for feeding deterrent production and to isolate and identify feeding deterrent compounds, a new, rapid, and reliable laboratory bioassay was developed. This bioassay used the laboratory-reared harpacticoid copepod Tigriopus californicus and measured inhibition of feeding by measuring the fecal pellet production rate. The bioassay was capable of detecting deterrent compounds: (1) adsorbed onto ground fish food (a normally palatable food); (2) dissolved in a mixture of seawater and live Thalassiosira pseudonana cells (a species of diatom which had no feeding deterrent activity); and (3) present in live cell cultures. Method (2) was recommended for use in bioassay-guided fractionation (isolation of chemical compounds), as it was reliable, rapid, accurate, and easy to perform with large numbers of samples. The total bioassay time was < 48 h, and data collection required only a microscope. Methanolic cell extracts of several phytoplankton species were screened for feeding deterrent activity. Extracts from the diatom Phaeodactylum tricornutum and the dinoflagellate Gonyaulax grindleyi gave feeding deterrent responses, while extracts from the diatom Thalassiosira pseudonana gave no feeding deterrent responses. Live P. tricornutum cells deterred feeding at densities of 6x105 cells ml-1. This bioassay should provide a valuable tool in screening phytoplankton for feeding deterrent compounds and determining the chemical nature of these compounds. 相似文献
4.
Here we evaluate the effects of two quantitatively very important components of the water soluble fractions of fuel oils (naphthalene
and 1,2-dimethylnaphthalene, hereafter NAPH and C2-NAPH, respectively) on the survival, feeding and egg production rates,
and viability of eggs of the coastal copepod Paracartia (Acartia) grani. Acute toxicity responses resulted in lethal concentrations (LC50) of 2,535 and 161 μg l−1 for NAPH and C2-NAPH, respectively, with no evidence of narcotic effects. Hydrocarbon-specific differences in the toxicity
response indicate that sublethal effects (EC50) on feeding by C2-NAPH were likely driven by induced mortality, whereas NAPH
has direct negative effects on feeding. Sublethal effects on egg production rates followed a similar detrimental pattern to
the one exhibited by feeding rates, suggesting that the lower egg production rates were mediated by the decrease in feeding
rates. At the exposure time tested (24 h), the 50% reduction effective concentrations (EC50) determined for sublethal effects
were relatively high in comparison with hydrocarbons’ concentrations found under natural circumstances. Long exposure (4 days)
of P. grani adults to the tested hydrocarbons at concentrations well below the recorded EC50, however, had no significant effects on
feeding, egg production and hatching rates. The viability of the eggs was either not affected or only slightly influenced
when healthy eggs were incubated under very high concentrations (up to 6,400 and 700 μg l−1 NAPH and C2-NAPH, respectively). The significance of the effects of oil spills on marine zooplankton communities is discussed
in light of the results presented in this study. 相似文献
5.
Pure compounds isolated from the cyanobacterium Lyngbya majuscula Gomont were evaluated in an artificial diet for their influence on the feeding preferences of the sea hare Stylocheilus longicauda (Quoy and Gaimard, 1824), which lives in and feeds on this filamentous cyanobacterium (blue-green alga). Microcolin B, ypaoamide,
malyngolide and other natural products acted as feeding deterrents at natural concentrations. At lower concentrations, sea
hares were indifferent to ypaoamide and malyngolide in their diets. In contrast, barbamide stimulated sea hare feeding at
the concentrations normally found in L. majuscula. Malyngamides and majusculamides, the most common natural products found in samples of L. majuscula from Guam, increased sea hare feeding at low concentrations and inhibited feeding at the higher concentrations that occurred
in some collections of L. majuscula. Dietary selection of cyanobacteria by S. longicauda may be regulated by the concentration of specific chemical cues produced by L. majuscula.
Received: 28 January 1997 / Accepted: 24 April 1998 相似文献
6.
Summary. The effect of rearing larvae of Trichoplusia ni on
individual feeding deterrents or on binary mixtures of deterrents
on their subsequent gustatory sensitivity was measured
in paired choice leaf disc bioassays. Our working hypothesis
was that mixtures of antifeedants (pure allelochemicals)
would mitigate decreased feeding deterrent response following
prolonged exposure in this generalist herbivore. Neonate
larvae were reared on cabbage leaves treated with individual
feeding deterrents (digitoxin, thymol, toosendanin or xanthotoxin),
or with binary mixtures of these until the third instar.
Feeding deterrent responses to each antifeedant or mixture
was then determined in a leaf disc choice bioassay. All of the
mixtures produced additive deterrence when presented to
naïve larvae. Larvae reared on individual antifeedants
showed a significantly decreased feeding deterrent response
(except to digitoxin), whereas larvae reared on binary mixtures
of antifeedants did not show a decreased feeding deterrent
response to any of them. Such mixtures were synergistic
in terms of their feeding deterrence to experienced larvae.
Our experiment supports the hypothesis (Jermy 1986) that
mixtures of deterrents can prevent decreased feeding deterrent
response following prolonged exposure, and provides one
explanation for the multiplicity of chemical defenses found
in many plants. 相似文献
7.
Feeding association of the copepod Rhincalanus gigas with the tunicate salp Salpa thompsoni in the southern ocean 总被引:1,自引:1,他引:1
During a repeat grid survey and drogue study carried out in the Lazarev Sea in the austral summer of 1994 to 1995, a sudden
collapse of a rich population of the tunicate Salpa thompsoni was observed at the onset of a phytoplankton bloom. This may have been related to the inability of salps to regulate their
filtration rate and avoid clogging of their filtering apparatus at particle concentrations ≥1 mg (chlorophyll a) m−3. It was at this stage that large numbers of salp individuals had their branchial cavities invaded by the copepod Rhincalanus gigas. Incubations, to compare the feeding rates of R.␣gigas in the presence and absence of salps, showed that copepods are able to utilize the high concentrations of microplankton accumulated
in the food strand of the salp, thus enhancing their grazing efficiency. This is likely to represent a typical form of opportunistic
parasitism. However, the timing of the invasion, and the observation that most salps could survive prolonged exposure to R. gigas invasion, suggest that the association may also constitute a novel type of symbiosis. S.␣thompsoni could potentially benefit from R. gigas cleaning its filtering apparatus when clogging due to high particle concentrations occurs.
Received: 15 July 1996 / Accepted: 20 July 1996 相似文献
8.
Two important issues in the studies of harmful algae include ecological role of the toxic compounds and their fate through the food web. The aims of this study were to determine whether the production of domoic acid is a strategy evolved to avoid predation and the role of copepods in the fate of this toxic compound through the food web. The copepod Acartia clausi was fed with single and mixed cultures of the toxic diatom Pseudo-nitzschia multiseries and the non-toxic diatom Pseudo-nitzschia delicatissima. Ingestion rate as a function of diatom abundance was the same for the toxic and non-toxic Pseudo-nitzschia species, indicating no selective feeding behaviour against P. multiseries. The toxins ingested by the copepods did not affect mortality, feeding behaviour, egg production and egg hatching of the copepods. Copepods assimilated the 4.8% of the total domoic acid ingested. Although the amount of toxins daily detoxificated by the copepods was 63.6%, the copepods accumulated domoic acid in their tissues. We conclude that domoic acid is not toxic for copepods and, probably for this reason, this toxin does not act as feeding deterrent for copepods. However, even though the production of domoic acid has apparently not evolved to deter predation, copepods may play an important role on the fate of this toxic compound through the marine food web. 相似文献
9.
Summary. Chemical defense against herbivores has rarely been investigated for freshwater plants, possibly due to the common misconception
that herbivory on aquatic macrophytes is low and would not select for chemical defenses. In previous work, the freshwater
angiosperm Saururus cernuus was shown to be a low preference food for omnivorous crayfish despite its high nutrient value and relatively soft texture.
We used feeding by the crayfish Procambarus clarkii to guide fractionation of the deterrent lipid-soluble extract of this plant, leading to the identification of seven deterrent
lignoid metabolites, (–)-licarin A, (+)-saucernetin, (–)-dihydroguaiaretic acid, (–)-sauriols A and B, (–)-saucerneol, and
(–)-saucerneol methyl ether. Lignans have been implicated in terrestrial plant chemical defenses as insect growth inhibitors,
insect toxins, nematocides, antibacterial, and antifungal agents. However, these activities have rarely been demonstrated
using ecologically relevant methodologies in terrestrial systems, and never before in freshwater systems. The widespread nature
of lignans amongst very distantly related plants, along with their rich diversity of molecular structure, suggests that they
could play a large role in mediating plant-herbivore interactions. In addition to the lignoid compounds we identified, there
were other compounds present in low concentration or unstable compounds that were deterrent, that did not appear to be lignans,
but that we were unable to identify. This plant thus appears to be defended by a complex mixture of natural products.
Received 6 June 2000; revised 23 August 2000; accepted 2 September 2000 相似文献
10.
Physiological responses of Mytilus chilensis exposed to the toxic dinoflagellate Alexandrium catenella were measured over 21 days in the laboratory and were compared with control mussels not exposed to the dinoflagellate. Mussels
were collected from culturing ropes at Yaldad Bay, southern Chile (43o08′S 73o44′W), in August 2004 and acclimated to laboratory
conditions for one week prior to the experiment. After 8 days, the paralytic shellfish poisoning (PSP) toxins (i.e. saxitoxin)
in the tissues of exposed mussels exceeded safe levels for human consumption. Clearance rates, ingestion of organic matter,
and absorption efficiency of exposed mussels were significantly lower than those of controls on day 0, but this was followed
by an increase on day 3. The exposed mussels also increased their excretion rate over time, and this increase was significantly
correlated with the accumulation of PSP toxins in their tissues. Oxygen consumption was not affected by the PSP toxins. The
scope for growth (SFG) on day 0 was negative in exposed mussels, but it increased during the experiment. Although feeding
activity and absorption efficiency were adversely affected during the first few days of exposure to PSP toxins from A. catenella in the laboratory, the M. chilensis cultured in Yaldad Bay may have evolved mechanisms that allow them to exploit the toxic dinoflagellate as a food source. 相似文献
11.
Summary. While many marine molluscs have been suggested to use aposematic coloration to avoid predation, few studies have tested the
ability of marine predators to learn to associate colors with distasteful prey. In field experiments, we tested the ability
of two populations of reef fishes to discriminate among red, yellow, and black artificial nudibranch models when one color
was paired with a feeding deterrent. We offered fishes (1) the models without any feeding deterrents, (2) the models with
a feeding deterrent coated onto one color, and (3) the models without deterrents again. If reef fishes learn to associate
colors with noxious prey, we expected the color paired with the feeding deterrent to be eaten less frequently in the final
assay than the initial assay. In both populations, fishes formed clear associations between color and feeding deterrence.
However, when the experiment was repeated in one population, changing the color paired with the feeding deterrent, fishes
did not form an association between color and feeding deterrence. In this case, prior learning may have affected subsequent
trials. Our study indicates that common colors of nudibranchs are recognizable by fishes and can be associated with noxious
prey.
Received 24 September 1998; accepted 18 December 1998. 相似文献
12.
Heather Elizabeth Braid Jonathan Deeds Stacey Lea DeGrasse John James Wilson Josephine Osborne Robert Harland Hanner 《Marine Biology》2012,159(1):25-31
In fall of 2009, several mass strandings of Humboldt squid (Dosidicus gigas) occurred on Vancouver Island (49°7′60N 125°54′0W). Morphological dissections coupled with DNA barcoding of stomach contents
revealed Sardinops sagax (Pacific sardine) and Clupea pallasii (Pacific herring) as their primary prey. Plastic nurdles, fishing line, bull kelp, eelgrass, and a guillemot feather were
also discovered. The primary prey, Pacific sardines and Pacific herring, are known to bioaccumulate paralytic shellfish toxins
(PSTs); additionally, both PSTs and domoic acid (DA) have been implicated in other mass strandings. Therefore, stomach contents,
and other tissues when possible, were tested for PSTs and DA. Testing revealed DA concentrations below regulatory guidance
levels for human consumption, yet PSTs were well in excess. Though we cannot conclude that PSTs were the definitive cause
of the strandings, our findings are the first report of PSTs in D. gigas. 相似文献
13.
Anping Zhang Xuemei Xie Jing Ye Chunmian Lin Xiaoyan Hu 《Environmental Chemistry Letters》2011,9(3):369-373
In recent years, the stereoselective toxicity of chiral organophosphorus pesticides has received increasing attention from
environmental toxicology scientists. In an attempt to explore the stereoselective effects of chiral organophosphorus pesticides
on non-target organisms and enzymes, this work investigated the stereoselective toxicity and inhibition of malathion, malaoxon
and isomalathion on Daphnia magna and on acid α-naphthyl acetate esterase extracted from wheat flour, respectively. Toxicity differences were observed between
the two enantiomers of malathion and malaoxon and among the four stereoisomers of isomalathion in the LC50 values on D. magna and the IC50 values on acid α-naphthyl acetate esterase. Enantiomers with (R)-configuration in all the tested compounds showed
higher toxicity to D. magna than their (S)-forms and racemic forms. Racemic malaoxon and isomalathion showed the strongest inhibition on acid α-naphthyl
acetate esterase compared to their respective enantiomers and stereoisomers. 相似文献
14.
Miina Karjalainen Betina Kozlowsky-Suzuki Maiju Lehtiniemi Jonna Engström-Öst Harri Kankaanpää Markku Viitasalo 《Marine Biology》2006,148(4):683-691
Cyanobacterial blooms are a common phenomenon in the Baltic Sea, and the hepatotoxin nodularin has been frequently detected
in certain Baltic Sea fishes and mussels. However, there is no knowledge about the naturally occurring concentrations of nodularin
in Baltic Sea zooplankton. The aim of this study was to survey the concentrations of nodularin in natural zooplankton assemblages,
and to study the depuration of nodularin in one common copepod species, Eurytemora affinis, experimentally. The nodularin concentrations in common zooplankton species were determined from field-collected samples
from the northern Baltic Proper in 2001 and 2002, during cyanobacterial blooms, and the samples were analysed by ELISA immunoassay.
Nodularin could be detected from the field-collected zooplankton, suggesting that during a natural bloom event toxins accumulate
in their tissues. The concentrations were relatively low (0.07±0.01 μg g−1 ww), ranging from below detection limit to 0.62 μg g−1 ww. Some variation occurred in the concentrations between species and years; generally concentrations were higher in 2001
than in 2002. In the depuration experiment E. affinis copepods were fed with toxic Nodularia spumigena for 24 h, and their toxin contents were monitored for 24 h after transferring them to filtered seawater. A rapid decrease
in nodularin concentrations occurred during the first 0.5–3 h after the exposure. However, after a 24-h depuration period
in filtered seawater, nodularin could be still detected in E. affinis tissues, indicating that part of the accumulated nodularin, or its derivatives, could be transferred to planktivores. 相似文献
15.
Concentrations of paralytic shellfish poisoning (PSP) toxins in toxic dinoflagellate cells and in marine planktonic copepods were monitored during the bloom of Alexandrium tamarense in Hiroshima Bay, western Japan. Concentration of the toxins retained by copepods was a function of the ambient toxin concentration, i.e. the product of A. tamarense cell density and cellular toxicity. The toxin concentration in copepods increased with the increase of toxicants in the seawater then leveled off, but decreased significantly at higher concentrations. In the field, the maximum toxin concentration was 1.2 pmol ind-1, whereas in the laboratory, the copepod Acartia omorii accumulated a much higher concentration of PSP toxins (24 pmol ind-1). Feeding avoidance against Alexandrium tamarense and a shift to alternative food sources such as diatoms in the field might keep their toxin levels lower than their potentially maximum level. The copepod toxin levels in the field were not so high as to cause an instantaneous lethal effect on their predator fishes but may reach possibly lethal levels after a few days' continuous feeding. Overall toxin retention by copepods after 12 h feeding and 2 h starvation was only 2.5% of total ingested toxins, which suggested that a significant amount of toxins was released into the seawater. Measurements of toxin reduction and gut evacuation suggested that the toxins were removed through both fecal evacuation and metabolism (e.g. excretion, decomposition and transformation). The results, as a whole, imply that copepods can be a link for PSP toxin flux in both pelagic and benthic food webs and can also be a sink for toxins by metabolizing and removing them from the environment.Communicated by T. Ikeda, Hakodate 相似文献
16.
Nicole E. Phillips 《Marine Biology》2011,158(10):2335-2342
This study evaluated whether larvae of the Indo-Pacific vermetid gastropod Dendropoma maximum are obligate planktotrophs, or whether they exhibit an intermediate feeding strategy. Experiments were conducted in Moorea,
French Polynesia (149°50′W, 17°30′S), Sep–Oct 2009, to examine D. maximum larval growth and metamorphic responses to different diets and amounts of food. Dendropoma maximum larvae required particulate food to undergo metamorphosis, but were able to survive and grow in the absence of food for up
to 20 days. Larvae in Low and Unfed food treatments exhibited phenotypic plasticity by growing a larger velum (the larval
feeding structure) compared with those in high food. Unfed D. maximum larvae had a slower initial growth rate; however, by 11-day post-hatch fed and unfed larvae had converged on the same mean
shell height (553 μm), which was only 10% larger than the initial size at hatching. Therefore, although the nutritional strategy
of D. maximum larvae is best described as obligate planktotrophy, it appears to approach an intermediate feeding strategy. 相似文献
17.
The pelagic copepod Calanus pacificus ranges nearly continuously across temperate-boreal regions of the North Pacific Ocean and is currently divided into three
subspecies—C. pacificus oceanicus, C. pacificus californicus, C. pacificus pacificus—based on subtle morphological differences and geographic location. The relation between geography and genetic differentiation
was examined for 398 C. pacificus individuals sampled from six widely distributed locations across the North Pacific, including an open ocean site and coastal
sites on both sides of the North Pacific basin. For each individual copepod, the DNA sequence was determined for a 421-bp
region of the mitochondrial coxI gene (mtCOI). A total of sixty-three different mtCOI sequences, or haplotypes, were detected,
with a sequence divergence between haplotypes of 0.2–3.1%. The number and distribution of haplotypes varied with sampling
location; 12 haplotypes were distributed across multiple sampling locations, and 51 occurred at only one location. Five genetically
distinct populations were detected based on F
ST values. Haplotype minimum spanning networks, nucleotide divergence and F
ST values indicated that individuals from coastal sites in the North Pacific Ocean were more closely related to each other than
to individuals from the open ocean site at Station P. These results provide genetic support for the designation of two subspecies—a
coastal subspecies that consists of what is currently referred to as C. p. pacificus and C. p. californicus and an open ocean subspecies C. p. oceanicus. This work also indicates that planktonic copepods with potentially high dispersal capacity can develop genetically structured
populations in the absence of obvious geographic barriers between proximate locales within an ocean basin. 相似文献
18.
L. Chalker Scott 《Marine Biology》1995,123(4):799-804
The marine harpacticoid copepod, Tigriopus californicus (Baker), is a successful colonizer of supralittoral splash pools from Torch Bay, Alaska, to Baja California, Mexico. As these pools are subject to abundant amounts of direct solar radiation, it was of interest to determine the sensitivity of T. californicus to ultraviolet-B (UV-B, 290 to 320 nm) radiation. During 1980, copepods were raised under diurnal conditions in the laboratory and fed a mixture of unicellular algae and bacteria. Larval and adult stages were irradiated for 0 to 26 h on a rotating turntable under enhanced ultraviolet radiation. Following irradiation, the copepods were maintained in the culture area and checked daily for survival. All life stages of T. californicus tolerated enhanced UV-B radiation irrespective of exposure period; in contrast, survival of an irradiated planktonic copepod, Acartia clausii (Giesbrecht), was significantly lower. Additionally, there appeared to be asex ratio shift in adults that developed from the youngest naupliar stages (N1/N2) of T. californicus that were irradiated. Extraction and tentative identification of the pigment(s) responsible for the bright orange color of the carapace of T. californicus were performed. These pigments may function to absorb UV radiation and protect internal structures from photochemically induced damage. 相似文献
19.
Observations of copepod feeding and vertical distribution under natural turbulent conditions in the North Sea 总被引:1,自引:0,他引:1
We present results of simultaneous measurements of turbulent-dissipation rate, zooplankton vertical distribution and copepod
gut pigments in the northern North Sea. Analysis shows that some, but not all, copepods (by species, sex and stage) exhibit
significant dependence on turbulence in respect to vertical distribution and feeding rate. Oithona similis (female and copepodite stages) exhibits an avoidance of the surface layer when turbulence is strong there. For the range
of turbulence (10−7 to 10−3 m2 s−3) and ambient chlorophyll concentration (0.5–0.8 μg l−1) encountered, Calanus spp. and Metridia lucens exhibited a significant negative response in feeding-rate index with increasing turbulence. Centropages typicus and Pseudocalanus spp. also exhibited a negative response but of less significance.
Received: 12 October 2000 / Accepted: 11 December 2000 相似文献
20.
The pelagic copepod Calanus pacificus ranges nearly continuously across temperate-boreal regions of the North Pacific Ocean and is currently divided into three
subspecies—C. pacificus oceanicus, C. pacificus californicus, C. pacificus pacificus—based on subtle morphological differences and geographic location. The relation between geography and genetic differentiation
was examined for 398 C. pacificus individuals sampled from six widely distributed locations across the North Pacific, including an open ocean site and coastal
sites on both sides of the North Pacific basin. For each individual copepod, the DNA sequence was determined for a 421-bp
region of the mitochondrial coxI gene (mtCOI). A total of sixty-three different mtCOI sequences, or haplotypes, were detected,
with a sequence divergence between haplotypes of 0.2–3.1%. The number and distribution of haplotypes varied with sampling
location; 12 haplotypes were distributed across multiple sampling locations, and 51 occurred at only one location. Five genetically
distinct populations were detected based on F
ST values. Haplotype minimum spanning networks, nucleotide divergence and F
ST values indicated that individuals from coastal sites in the North Pacific Ocean were more closely related to each other than
to individuals from the open ocean site at Station P. These results provide genetic support for the designation of two subspecies—a
coastal subspecies that consists of what is currently referred to as C. p. pacificus and C. p. californicus and an open ocean subspecies C. p. oceanicus. This work also indicates that planktonic copepods with potentially high dispersal capacity can develop genetically structured
populations in the absence of obvious geographic barriers between proximate locales within an ocean basin. 相似文献