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1.
The thecate dinoflagellate Scrippsiella trochoidea is a cosmopolitan, bloom-forming alga that has been generally considered non-toxic. Here, we report that environmentally
relevant cell densities (104 cells mL−1) of Scrippsiella trochoidea strains isolated from the Northwest Atlantic Ocean caused 100% mortality in Eastern oyster (Crassostrea virginica) larvae during 3-day exposures while parallel control larvae exhibited 100% survival. S. trochoidea also exhibited lethal effects on Northern quahog (Mercenaria mercenaria) larvae (70% mortality during 3-day exposure) but were non-toxic to juvenile fish (Cyprinodon variegates). The cultures of S. trochoidea were more lethal to Northern quahog larvae than ten other species of harmful algae, including the highly toxic species Cochlodinium polykrikoides. Scrippsiella trochoidea cultures within later stages of growth were more toxic than exponential growth stages to bivalve larvae, and the toxicity
was dose dependent. Furthermore, toxicity was maintained in the cultures that were sonicated, boiled, and frozen as well as
in resuspended residues of the culture but was significantly lower in cell-free culture media. Collectively, these results
suggest that S. trochoidea causes mortality in bivalve larvae through a physicochemical rather than strictly chemical mechanism, such as clogging of
larval feeding apparatuses by materials produced by S. trochoidea (e.g., lipids, extracellular polysaccharides, and/or cell debris) which accumulate as cells in culture or blooms age. This
is the first report of the lethal effects of Scrippsiella trochoidea on shellfish larvae. 相似文献
2.
Myong Hwan Sohn Kyung Won Seo Yong Seok Choi Sang Joon Lee Young Sil Kang Yang Soon Kang 《Marine Biology》2011,158(3):561-570
The marine dinoflagellate Cochlodinium polykrikoides is a harmful and highly motile algal species. To distinguish between the motility characteristics of solitary and chain-forming
cells, the swimming trajectories and speeds of solitary cells and 2- to 8-cell chains of C. polykrikoides were measured using a digital holographic particle tracking velocimetry (PTV) technique. C. polykrikoides cells exhibited helical swimming trajectories similar to other dinoflagellate species. The swimming speed increased as the
number of cells in the chain increased, from an average of 391 μm s−1 (solitary cells) to 856 μm s−1 (8-cell chain). The helix radius R and pitch P also increased as the number of cells in the chain increased. R increased from 9.24 μm (solitary cell) to 20.3 μm (8-cell chain) and P increased from 107 μm (solitary cell) to 164 μm (8-cell chain). The free thrust-generating motion of the transverse flagella
and large drag reduction in the chain-forming cells seemed to increase the swimming speed compared to solitary cells. The
measured swimming speeds agreed with those from field observations. The superior motility of chain-forming C. polykrikoides cells may be an important factor for its bloom, in addition to the factors reported previously. 相似文献
3.
Carl Van Colen J. Lenoir A. De Backer B. Vanelslander M. Vincx S. Degraer T. Ysebaert 《Marine Biology》2009,156(10):2161-2171
The role of multi-species benthic diatom films (BDF) in the settlement of late pediveliger larvae of the bivalve Macoma balthica was investigated in still-water bioassays and multiple choice flume experiments. Axenic diatom cultures that were isolated
from a tidal mudflat inhabited by M. balthica were selected to develop BDF sediment treatments characterized by a different community structure, biomass, and amount of
extracellular polymeric substances (EPS). Control sediments had no added diatoms. Although all larvae settled and initiated
burrowing within the first minute after their addition in still water, regardless of treatment, only 48–52% had completely
penetrated the high diatom biomass treatments after 5 min, while on average 80 and 69% of the larvae had settled and burrowed
into the control sediments and BDF with a low diatom biomass (<3.5 μg Chl a g−1 dry sediment), respectively. The percentage of larvae settling and burrowing into the sediment was negatively correlated
with the concentration of Chl a and EPS of the BDF. This suggests higher physical resistance to bivalve penetration by the BDF with higher diatom biomass
and more associated sugar and protein compounds. The larval settlement rate in annular flume experiments at flow velocities
of 5 and 15 cm s−1 was distinctly lower compared to the still-water assays. Only 4.6–5.8% of the larvae were recovered from BDF and control
sediments after 3 h. Nonetheless, a clear settlement preference was observed for BDF in the flume experiments; i.e., larvae
settled significantly more in BDF compared to control sediments irrespective of flow speed. Comparison with the settlement
of polystyrene mimics and freeze-killed larvae led to the conclusion that active selection, active secondary dispersal and,
at low flow velocities (5 cm s−1), passive adhesion to the sediment are important mechanisms determining the settlement of M. balthica larvae in estuarine biofilms. 相似文献
4.
This study provides information about differences in composition of ingested zooplankton amongst bivalve species coexisting
in the same area in a period from May 2009 to December 2010. The study was conducted at the Mali Ston Bay (42°51′ N, 17°40′
E)—the most important bivalve aquaculture area in the eastern Adriatic Sea. Stomach content analysis was performed on cultured
species—Ostrea edulis and Mytilus galloprovincialis, and commercially important bivalve species from their natural environment—Modiolus barbatus and Arca noae. Results confirmed carnivory in bivalves, both from natural and cultured populations, but cultured species had higher numbers
of zooplankters than those living on the seabed. The most abundant taxa were bivalve larvae, followed by tintinnids, copepods,
unidentified eggs and gastropod larvae. Recorded numbers of bivalve larvae in M. galloprovincialis stomach were the highest so far reported and show that mussels impact the availability of natural spat. 相似文献
5.
Great scallop, Pecten maximus, and blue mussel, Mytilus edulis, clearance rate (CR) responses to low natural seston concentrations were investigated in the laboratory to study (1) short-term
CR variations in individual bivalves exposed to a single low seston diet, and (2) seasonal variations in average CR responses
of bivalve cohorts to natural environmental variations. On a short temporal scale, mean CR response of both species to 0.06 μg L−1 chlorophyll a (Chl a) and 0.23 mg L−1 suspended particulate matter (SPM) remained constant despite large intra-individual fluctuations in CR. In the seasonal study,
cohorts of each species were exposed to four seston treatments consisting of ambient and diluted natural seston that ranged
in mean concentration from 0.15 to 0.43 mg L−1 SPM, 0.01 to 0.88 μg L−1 Chl a, 36 to 131 μg L−1 particulate organic carbon and 0.019 to 0.330 mm3 L−1 particle volume. Although food abundance in all treatments was low, the nutritional quality of the seston was relatively
high (e.g., mean particulate organic content ranged from 68 to 75%). Under these low seston conditions, a high percentage
of P. maximus (81–98%) and M. edulis (67–97%) actively cleared particles at mean rates between 9 and 12 and between 4 and 6 L g−1 h−1, respectively. For both species, minimum mean CR values were obtained for animals exposed to the lowest seston concentrations.
Within treatments, P. maximus showed a greater degree of seasonality in CR than M. edulis, which fed at a relatively constant rate despite seasonal changes in food and temperature. P. maximus showed a non-linear CR response to increasing Chl a levels, with rates increasing to a maximum at approximately 0.4 μg L−1 Chl a and then decreasing as food quantity continued to increase. Mean CR of M. edulis also peaked at a similar concentration, but remained high and stable as the food supply continued to increase and as temperatures
varied between 4.6 and 19.6°C. The results show that P. maximus and M. edulis from a low seston environment, do not stop suspension-feeding at very low seston quantities; a result that contradicts previous
conclusions on the suspension-feeding behavior of bivalve mollusks and which is pertinent to interpreting the biogeographic
distribution of bivalve mollusks and site suitability for aquaculture. 相似文献
6.
Yasuhiro Yamasaki Sou Nagasoe Tadashi Matsubara Tomoyuki Shikata Yohei Shimasaki Yuji Oshima Tsuneo Honjo 《Marine Biology》2007,152(1):157-163
We investigated the growth interaction between Cochlodinium polykrikoides and Akashiwo sanguinea using bi-algal cultures. When cultured together, morphologically abnormal cells of A. sanguinea appeared and the growth of A. sanguinea notably decreased. When C. polykrikoides and A. sanguinea were cultured separately in inner and outer wells separated by a membrane with a pore size of 3 μm, neither species showed
suppressed growth and no morphologically abnormal cells of A. sanguinea were observed. Furthermore, filtrates from C. polykrikoides cultures did not affect the cell morphology or the growth of A. sanguinea. When the abnormal cells of A. sanguinea were transferred from bi-algal cultures into fresh medium and cultured as a mono-algal culture, cells recovered their normal
morphology and multiplied. Therefore, the growth inhibition and formation of morphologically abnormal cells of A. sanguinea would be induced by constant cell contact with C. polykrikoides. 相似文献
7.
Harmful algal blooms produced by the marine ichthyotoxic dinoflagellate Cochlodinium polykrikoides are responsible for mass mortalities of wild and farmed fish globally. This study compared the cytotoxic mechanisms of C. polykrikoides total extract on both trout and rat liver hepatocytes. Trout hepatocytes were more sensitive than rat hepatocytes against C. polykrikoides extract. The effective concentration 50 after 3 hour incubation (EC503hr) concentrations found for C. polykrikoides extract in trout and rat hepatocytes (i.e., 50% membrane lysis in 3 hr) were Eq. 1 cell/ml and Eq. 240 cell/ml, respectively. C. polykrikoides extract exposure in both isolated trout and rat hepatocytes resulted in membrane lysis, reactive oxygen species formation, glutathione depletion, collapse of mitochondrial membrane potential, ATP depletion, increase in adenosine diphosphate (ADP)/adenosine triphosphate (ATP) ratio, cytochrome c release into the hepatocyte cytosol, and activation of caspases cascade. Trout hepatocyte toxicity was also associated with lysosomal membrane injury. Mitochondrial permeability transition in both trout and rat hepatocytes produced cytochrome c release from the mitochondrial intramembrane space into the cytosol. Thus, the cytochrome c release triggered activation of caspase-3 and apoptosis. Finally, data demonstrated that C. polykrikoides extract may induce more apoptotic phenotype in rat than trout hepatocytes, which in the latter favored predominantly necrotic mode of cell death. 相似文献
8.
Rates of respiration and protein synthesis were measured during embryonic and larval development of Antarctic asteroids with
different life-history modes (non-feeding and feeding larvae: Acodontaster hodgsoni, Porania antarctica, Odontaster meridionalis). Patterns of respiration for these species all show an increase during embryogenesis, with subsequent maintenance of routine
respiration (“starvation resistance”), even in the absence of food for ~4 months (O. meridionalis). Fractional rates of protein synthesis (i.e., rate per unit mass of whole-body protein content) in the Antarctic larvae
are essentially identical to those of temperate species. Larvae of O. meridionalis had an average fractional synthesis rate of 0.52% ± 0.05 h−1 at −1.0°C, which is comparable to the temperate asteroid Asterina miniata at 0.53% ± 0.14 h−1 at 15°C. For embryos of the asteroids A. hodgsoni and P. antarctica, fractional rates of protein synthesis (~0.2% h−1) also are comparable to those reported for embryos of temperate echinoderm species. While rates of synthesis are high, rates
of protein deposition are relatively low (percent of protein synthesized that is retained for growth). During a ~4 month growth
period for larvae of O. meridionalis, the average protein depositional efficiency was 5.2%. This contrasts with higher rates of depositional efficiency reported
for similar developmental stages of temperate echinoderm species. The biological significance of maintaining high rates of
macromolecular synthesis for species with low rates of cell division and low protein depositional efficiencies is intriguing
in the context of understanding the mechanistic bases of extended life spans and dispersal potential in response to changing
Antarctic environments. 相似文献
9.
Single-step species identification of bivalve larvae using multiplex polymerase chain reaction 总被引:5,自引:0,他引:5
One of the biggest obstacles to studying recruitment variation in marine bivalves is the need to collect and process large
numbers of plankton samples. Larval bivalves are notoriously difficult, if not impossible, to identify to species using morphological
criteria alone. Remote time-series collections could satisfy the sampling challenge, but efficient identification techniques
must be developed to obtain species-specific data. Thus, we have developed a multiplex polymerase chain reaction (PCR) identification
assay in which a single reaction is capable of accurate and efficient discrimination of five target bivalve species based
on the size of cytochrome oxidase I products. The assay was tested with cultured and field-sampled larvae as well as adult
genomic DNAs. Using a single whole larva as template, multiplex PCR reactions were capable of discriminating among the commercially
important bivalves: Mercenaria mercenaria, Argopecten irradians, Mulinia lateralis, Spisula solidissima and Mya arenaria. Overall accuracy was 92%, including very few false positives. The efficiency of this assay stems from its ability to discriminate
multiple target species with a single molecular step that ultimately can be automated to process large numbers of larvae.
Received: 30 March 2000 / Accepted: 10 July 2000 相似文献
10.
Herring (Clupea harengus pallasi) spawning sites in Puget Sound, Washington overlap spatially and temporally with blooms of Alexandrium catenella, a toxic dinoflagellate species responsible for paralytic shellfish poisoning. Consequently, newly hatched herring larvae
may be regularly exposed to the suite of dissolved paralytic shellfish toxins that are released into the water column from
toxic cells during blooms. To date, virtually nothing is known about the impacts of these neurotoxins on early developmental
stages of marine fish. In the present study, herring larvae at three ages, 0 days post hatch (dph), 4 dph, and 11 dph, were
exposed to dissolved saxitoxin (STX) in 24-h and multi-day exposures. All larvae were examined for sensorimotor function (i.e.
spontaneous swimming behavior and touch response). Significant reductions in spontaneous and touch-activated swimming behavior
occurred within 1 h of exposure. EC50s at 1 h of exposure were 1,500, 840, and 700 μg STX equiv. l−1 for larvae introduced to STX at 0, 4, and 11 dph, respectively. This progressive age-specific increase in STX-induced paralysis
suggests that older larvae were more sensitive to the toxin than younger larvae. Interestingly, herring larvae at all ages
exhibited a significant degree of neurobehavioral recovery within 4–24 h of continuous exposure relative to the 1-h time point.
This recovery of normal motor behaviors was not observed in previous studies with freshwater zebrafish (Danio rerio) larvae under the same continuous exposure conditions, suggesting that an adaptive detoxification or toxin sequestration
mechanism may have evolved in some species of marine fish larvae. Our data reveal that (1) dissolved STX is bioavailable to
marine finfish larvae, (2) the toxin is a paralytic agent with potencies that differ between developmental stages, and (3)
STX-induced sensorimotor inhibition occurs rapidly but is transient in marine larvae. Collectively, these results suggest
that dissolved algal toxins may have important sublethal effects on marine fish populations. 相似文献
11.
The quahog Mercenaria mercenaria has been introduced repeatedly to the Pacific coast of North America, but only one population is known to have become established.
In the 1970s, the population of M. mercenaria at Colorado Lagoon, in Los Angeles County, California (33o46′16″N, 118o08′05″W), was estimated at more than 300,000 individuals. To determine the current status of this non-indigenous species (NIS),
in 2009, we sampled 57 intertidal and 20 shallow subtidal plots, identifying and quantifying collected bivalves. No quahogs
were found among the 2,490 living bivalves in our plots, though two were found intertidally outside of our plots. The M. mercenaria population has thus collapsed since 1980, but the native community has not recovered. Six of the fourteen living bivalve
species we encountered were NIS; three are new records for the location, including the clam Venerupis philippinarum, which made up 87.6% of collected individuals. Though M. mercenaria is likely on its way to extinction on the US Pacific coast, the bivalve assemblage at this location remains heavily dominated
by NIS. 相似文献
12.
Ingestion of bivalve larvae by Mytilus edulis was investigated. Laboratory experiments revealed that ~ 90% of bivalve larvae offered to mussels was ingested and apparently fully digested. The shell of the bivalve larvae offered no protection against digestive processes, resulting in high larval mortality once inside the stomach. Stomach content analysis (September 2001–January 2003) showed that bivalve larvae were ingested by farmed mussels year-round, with the exception of March 2002. Numbers of ingested larvae were highest in October 2001 and May 2002, which coincides with known spawning times of farmed mussels in Ireland. Mussels ingested a large size-range of bivalve larvae, suggesting that all stages of the bivalve life cycle are vulnerable to predation. It is suggested that adult bivalves routinely filter larvae from the surrounding water and that, given the high biomass of mussels present in mussel farms, filtration by adult bivalves significantly reduces numbers of bivalve larvae in nearby waters.Communicated by J.P. Thorpe, Port Erin 相似文献
13.
Low temperature limits the rate of biochemical reactions and aerobic scopes of cold water ectotherms. To compensate for this
limiting effect, animals living in cold environments often possess physiological or morphological adaptations to maintain
vital functions. Cross-latitudinal comparison of aerobic capacities is one method to test which factors constrain activity
in thermally distinct environments particularly when congeneric studies are carried out on related species with conservative
ecology and habitat. Burrowing is a major aerobic activity of bivalve molluscs that is described here for the first time for
the tropical mangrove species Laternula truncata and Laternula boschasina and then compared with their Antarctic congener Laternula elliptica. About 80% of L. truncata (16.3–46.1 mm shell length) and 63% of L. boschasina (11.3–27.7 mm shell length) buried within 24 h at 28°C. The burrowing rate index (BRI = [3√wet weight/time to bury]×104) ranged between 1.1 and 20.2 for L. boschasina and 1.1–32.9 for L. truncata. These values are 2–3 orders of magnitude less than other tropical bivalve molluscs and are amongst the lowest recorded for
any bivalve. Comparisons with the Antarctic L. elliptica showed little or no differences in BRI (Q
10 of 1.0–1.2 for specimens of the same size). This is contrary to the general pattern over a wide range of bivalves, where
BRI increases with a Q
10 of between 2.9 and 6.4 between high latitudes and the equator. L. elliptica has 25–30% longer relative foot length than tropical congeners of the same size, which could be a morphological adaptation
compensating for reduced burrowing speeds in a colder environment. Burrowing rates within the genus Laternula could, however, also be maintained by differing habitat, ecological and physiological constraints on burrowing capability. 相似文献
14.
Blooms of the brevetoxin-producing Karenia brevis in the Gulf of Mexico cause massive fish kills, food poisoning and adverse respiratory effects in humans. Sedimentation of
toxic cells following inert clay application could reduce toxin incorporation by commercially important suspension-feeding
bivalves and thus prevent direct public health impacts, but could potentially lead to brevetoxin (PbTx) accumulation by benthic
deposit-feeders. The goal of this study was therefore to compare suspension- and deposit-feeding as pathways for brevetoxins.
We investigated: (1) the effect of toxic K. brevis on both feeding modes using a facultative deposit-suspension feeding tellinid bivalve, the clam Macoma balthica, as a model species and (2) the relative effectiveness of brevetoxin transfer via suspension- and deposit-feeding over 24-h
exposure. Sedimentation of K. brevis was achieved by treatment with 0.25 g phosphatic clay l−1 and brevetoxin concentrations were measured by ELISA. Karenia brevis reduced both suspension- and deposit-feeding activity. This study demonstrates that brevetoxins can be rapidly accumulated
by a surface deposit-feeding bivalve from sedimented K. brevis cells and that comparable toxin levels can be attained by both suspension- and deposit-feeding modes [1.2–1.6 μg PbTx (g
tissue wet weight)−1]. Deposit-feeding clams generally do not pose a direct threat to humans but may provide a pathway for brevetoxin food web
transfer. 相似文献
15.
C. G. Di Camillo F. Betti M. Bo M. Martinelli S. Puce C. Vasapollo G. Bavestrello 《Marine Biology》2012,159(7):1593-1609
Benthic suspension feeders in shallow waters develop in relation to the food availability and the variation of physical parameters giving rise to complex communities that act as a control factor on the plankton biomass. The aim of the work is to establish the role of the hydrozoan Eudendrium racemosum in the energy transfer from the plankton to the benthos in marine food chains of the North Adriatic Sea. This study highlighted that the hydroid biomass changed over time in relation to temperature and irradiance, and the highest abundance was observed during summer with about 400,000 polyps m−2 (about 19 g C m−2). The population suffered an evident summer decrease in relation to a peak of abundance of its predator, the nudibranch Cratena peregrina, whose adult specimens were able to eat up to 500 polyps day−1 and reached an abundance of 10 individuals m−2. The gut content analysis revealed that the hydroid diet was based on larvae of other benthic animals, especially bivalves and that the amount of ingested preys changed during the year with a peak in summer when it was estimated an average predation rate of 13.7 mg C m−2 day−1. In July, bivalves represented over 60 % of the captured items and about 18 mg C m−2 day−1. Values of biomass of E. racemosum are the highest ever recorded in the Mediterranean Sea, probably supported by the eutrophic conditions of the North Adriatic Sea. Moreover, our data suggest that settling bivalves provide the greater part of the energetic demand of E. racemosum. 相似文献
16.
Diane K. Stoecker Jason E. Adolf Allen R. Place Patricia M. Glibert Donald W. Meritt 《Marine Biology》2008,154(1):81-90
The bloom-forming dinoflagellates Prorocentrum minimum and Karlodinium veneficum can have detrimental effects on some marine life, including shellfish, but little is known about their effects on early life
history stages of bivalves. In the Chesapeake Bay region, blooms of these dinoflagellates overlap with the spawning season
of the eastern oyster, Crassostrea virginica. In laboratory experiments, we compared the effects of P. minimum and K. veneficum on the survival and development of embryos and larvae of the eastern oyster. At 104 cells ml−1, P. minimum did not have a negative effect on embryos and larvae in 2-day exposures. The yield of D-hinge larvae was equal to or greater
than in control treatments. At 2 × 104 cells ml−1 (approximately equal biomass to the P. minimum treatment) K. veneficum caused significant mortality to oyster embryos within 1 day and almost no embryos developed into D-hinge larvae. This effect
was not alleviated by the provision of an alternate food source (Isochrysis sp.). Significant mortality was observed when larvae were exposed to K. veneficum at concentrations of 104 cells ml−1 (approximately 5 ng ml−1 of karlotoxin). The K. veneficum cultures used in these experiments were relatively low in toxin content, more toxic strains could be expected to cause mortality
at lower cell concentrations. Survival and maturation of embryos and larvae may be reduced when spawns of the eastern oyster
coincide with high bloom densities of K. veneficum. 相似文献
17.
The life cycle of Lychnorhiza lucerna (Scyphozoa: Rhizostomeae) and the settlement preferences of its larvae were studied using laboratory-based rearing experiments.
Mature medusae of L. lucerna were collected from the beach of the Río de la Plata estuary, Argentina. This species displayed the typical metagenetic,
(i.e. medusoid and polypoid), life cycle reported for other rhizostomes. The fertilized eggs developed into motile and short
lived planulae. The majority of planulae settled on the air-water interface (p < 0.001). Of those that settled on the settlement plates provided, no significant differences were observed between styrene
slides, glass slides and shells of the bivalve Mactra isabelleana (p > 0.05). No planulae settled on stones. Several hours after planulae settled, they metamorphosed into sessile four-tentacled
scyphistomae. Most scyphistomae attached onto the air-water interface. At 19–22°C, the scyphistomae grew up to 22 tentacles
and reached 1,500 μm height. The scyphistomae increased their numbers by means of formation of podocysts from which new polyps
emerged and strobilated. Strobilation occurred 46 days after settlement. Only polydisk strobilation was observed and each
strobila always produced three ephyrae. After releasing ephyrae, strobilae returned to normal scyphistomae and were capable
of repeating strobilation. A single founder polyp was estimated to produce up to 60 ephyrae over 4 months. Ephyrae developed
into metephyrae 15 days after release at 19–22°C. In this paper we describe the morphological and some behavioural features
of L. lucerna in the polypoid and early medusoid stages. 相似文献
18.
Assimilation efficiencies and turnover rates of trace elements in marine bivalves: a comparison of oysters, clams and mussels 总被引:2,自引:0,他引:2
Assimilation efficiencies (AEs) and physiological turnover-rate constants (k) of six trace elements (Ag, Am, Cd, Co, Se, Zn) in four marine bivalves (Crassostrea virginica Gmelin, Macoma balthica Linnaeus, Mercenaria mercenaria Linnaeus, and Mytilus edulis Linnaeus) were measured in radiotracer-depuration experiments. Egestion rates of unassimilated elements were highest during
the first 24 h of depuration and declined thereafter. Significant egestion of unassimilated Co, however, continued for up
to 5 d in Macoma balthica, Mercenaria mercenaria and Mytilus edulis. With the exception of the extremely low values for 110 mAg, 109Cd, and 65Zn in C. virginica, physiological turnover-rate constants (k) showed no general pattern of variation among elements, bivalve species or food types, and were relatively invariant. Values
from ≤0.001 to 0.1 d−1 were observed, but excluding those for Co, most values were ≤0.04 d−1. In all four species, the AEs of Ag, Am, and Co were generally lower than those of Cd, Se, and Zn. The AEs of Ag, Cd, Se,
and Zn in these bivalves are directly related to the proportion of each element in the cytoplasmic fraction of ingested phytoplankton,
indicating that >80% of elements in a prey alga's cytoplasm was assimilated. C. virginica, Macoma balthica, and Mercenaria mercenaria assimilated ∼36% of the Ag and Cd associated with the non-cytoplasmic (membrane/organelle) fraction of ingested cells in
addition to the cytoplasmic fraction. The ratio of AE:k, which is proportional to the consumer–prey trace-element bioaccumulation factor (concentration in consumer:concentration
in prey) was generally greater for Cd, Se, and Zn than for Ag, Am, and Co. This ratio was lowest in Mytilus edulis, suggesting that this bivalve, the most widely employed organism in global biomonitoring, is relatively inefficient at accumulating
important elements such as Ag, Cd, and Zn from ingested phytoplankton.
Received: 7 February 1997 / Accepted: 24 February 1997 相似文献
19.
20.
Wrasses are abundant reef fishes and the second most speciose marine fish family, yet little is known of their larval swimming
abilities. In August 2010 at Moorea, Society Islands, we measured swimming ability (critical speed, Ucrit) of 80 settlement-stage
larvae (11–17 mm) of 5 labrid species (Thalassoma quinquevittatum [n = 67], Novaculichthys taeniourus [n = 6], Coris aygula [n = 5], Halichoeres trimaculatus [n = 1] and H. hortulanus [n = 1]) and 33 new recruits of T. quinquevittatum. Median (mdn) larval Ucrit was 7.6–12.5 cm s−1. In T. quinquevittatum (n = 67), larvae of 12.5–14.5 mm swam faster (mdn 16.9 cm s−1) than smaller or larger larvae (mdn 3.9 and 3.2 cm s−1, respectively). Labrid larvae Ucrit is similar to that of other similar-sized tropical larvae, so labrids and species with
comparable settlement sizes should have similar abilities to influence dispersal. Ucrit of T. quinquevittatum recruits decreased to 47–56% of larval Ucrit in 2 days, implying rapid physiological changes at settlement. 相似文献