共查询到20条相似文献,搜索用时 15 毫秒
1.
O. Lindén 《Marine Biology》1978,45(3):273-283
The effects of petroleum hydrocarbons from two crude oils and one fuel oil (No. 1) were studied on the ontogenic development of the Baltic herring Clupea harengus membras L. Herring eggs exposed to water-soluble fractions of the oils at the time of fertilization showed no decrease in numbers of fertilized eggs compared to eggs exposed 6 or 72 h after fertilization. During embryongenesis, treatment with 3.1 to 8.9 ppm or 3.3 to 11.9 ppm total oil hydrocarbons from light fuel oil and the two crude oils respectively, gave rise to alterations in embryonic activity, decreased heart rate, and premature or delayed hatching. Although many larvae hatched from eggs exposed to contaminated water (3.1 to 11.9 ppm total oil hydrocarbons), the majority of the (70 to 100%) were malformed or dead 1 day after hatching. Exposure of eggs to 5.4–5.8 ppm total oil hydrocarbons resulted in significantly (P<0.001) decreased lengths of the larvae. Increased temperature (from 9° to 14°C) aggravated the effects of the oils. The results are discussed in relation to the potential effects of oil spills and chronic oil pollution on fish eggs and larvae in the Baltic Sea. 相似文献
2.
The uptake and depuration of the water-sol‐uble fraction (WSF) of hydrocarbons of crude petroleum by Atlantic salmon (Salmosalar) has previously been examined in terms of whole muscle. The hypothesis that the tainting WSF in the muscle was retained primarily
by adipocytes has been investigated by the isolation of adipocytes and the subsequent analysis for hydrocarbons in adipocytes.
After 96 h exposure of market-sized Atlantic salmon to 0.2 ppm WSF, adipocytes isolated from the belly flap region of the
muscle tissue accumulated 14.3 times more WSF (59.4 ppm) than the dorsal white muscle (4.2 ppm), while 54% of the tainting
WSF in the dorsal white muscle was found to be stored in associated adipocytes. When returned to clean seawater, WSF accumulated
in the dorsal white muscle was released much faster than that in the adipocytes. These results indicated that the loose association
of WSF with the nonlipid portion of white muscle, mainly muscle cells and intercellular fluid, is responsible for the rapid
discharge of WSF from the dorsal muscle tissue in the early stages of depuration. After 4 d of depuration, the adipocytes
became the principal storage site of residual WSF in white muscle and the depuration of WSF from muscle tissue then reflected
the release of WSF from adipocytes in the muscle tissue. After 20 d of depuration, 10.7 ppm of tainting WSF in the form of
high molecular weight aromatic hydrocarbons (mainly C4-benzenes, naphthalene and alkylated naphthalenes) were still present in adipocytes, while in the dorsal white muscle only
a trace of total WSF was detected. Increases in the number of aromatic rings and the alkylations on the rings enhanced the
accumulation and retention of individual hydrocarbons in both adipocytes and white muscle. From these studies we conclude
that it is the adipocytes in the muscle tissue which control the actual accumulation and release of hydrocarbons in the whole
muscle tissue of Atlantic salmon.
Received: 21 August 1996 / Accepted: 26 September 1996 相似文献
3.
Mud crabs, Rhithropanopeus harrisii (Gould), were exposed continuously for 6 months after hatching to water-soluble fractions (WSF) of No. 2 fuel oil. Survival, growth and development rate were monitored during this time. The zoeal stages were the most sensitive to fuel oil. A 20% WSF (0.36 ppm total naphthalenes, 1.26 ppm total hydrocarbons) was acutely toxic to these stages. Of the zoeal stages, the first stage appeared to be the most sensitive. The combined duration of the 4 zoeal stages was significantly increased by increasing WSF exposure concentrations. The megalopa and crab stages were not particularly sensitive to continued petroleum hydrocarbon exposure, particularly when compared to zoeal stages. However, mean duration of the megalopa and first crab stages was significantly affected by oil exposure. Individuals which survived the highest exposure concentrations as larvae appeared to grow larger during the crab stages, so that at the end of 6 months comparably staged crabs were equal to or larger than both control crabs and those exposed to low WSF concentrations. Stage distributions at the end of 6 months showed no differences due to WSF exposure. Sex ratios, which could be determined at the end of 6 months, were approximately 1, indicating no sex-related differential sensitivity to WSF exposure, at least as larvae or juveniles. The data indicate that these crabs possess considerable ability to recover from the effects of chronic sublethal exposure to petroleum hydrocarbons. The most deleterious effects of oil pollution on this species may be due to its impact on larval recruitment into the adult population. 相似文献
4.
JOSÉ A. DÍAZ§ JAVIER PÉREZ-TRIS† JOSÉ L. TELLERÍA ROBERTO CARBONELL‡ TOMÁS SANTOS 《Conservation biology》2005,19(5):1578-1585
Abstract: We studied the effect of habitat fragmentation on female reproductive investment in a widespread lacertid lizard ( Psammodromus algirus ) in a mixed-forest archipelago of deciduous and evergreen oak woods in northern Spain. We captured gravid females in fragments (≤10 ha) and forests (≥ 200 ha) and brought them to the laboratory, where they laid their eggs. We incubated the eggs and released the first cohort of juveniles into the wild to monitor their survival. Females from fragments produced a smaller clutch mass and laid fewer eggs (relative to mean egg mass) than females of similar body size from forests. Lizards did not trade larger clutches for larger offspring, however, because females from fragments did not lay larger eggs (relative to their number) than females from forests. Among the first cohort of juveniles, larger egg mass and body size increased the probability of recapture the next year. Thus, fragmentation decreased the relative fecundity of lizards without increasing the quality of their offspring. Reduced energy availability, increased predation risk, and demographic stochasticity could decrease the fitness of lizards in fragmented habitats, which could contribute to the regional scarcity of this species in agricultural areas sprinkled with small patches of otherwise suitable forest. Our results show that predictable reduction of reproductive output with decreasing size of habitat patches can be added to the already known processes that cause inverse density dependence at low population numbers. 相似文献
5.
Timothy C. Sparkes 《Behavioral ecology and sociobiology》1996,39(6):411-417
In field surveys, laboratory observations and field-based assays of behavior, I examined the effects of size-dependent predation
risk on the interaction between size at reproductive maturity and maternal care behavior in the stream-dwelling isopod, Lirceus fontinalis. L. fontinalis exhibit population-specific sizes at reproductive maturity which result in population differences in predation risk during
the adult phase. Females from streams containing salamander larvae (that prefer small prey) mature at large sizes and then
become relatively safe from predation. Females from streams containing fish (that consume all size classes of prey equally)
mature at small sizes and remain at risk. I tested whether these differences in expected survival were reflected in the behavior
of females during the maternal phase (i.e., the period during which females exhibit maternal care). Female L. fontinalis carry developing juveniles inside a brood pouch. I simulated predatory attacks on gravid female L. fontinalis from the different population types and found that female behavior correlated with population differences in risk. When “attacked”,
females from streams with predatory fish (that experience high risk to adult females) released juveniles from the brood pouch,
whereas females from populations with predatory salamander larvae (that pose relatively little risk to adult females) did
not release juveniles. I discuss the results with reference to the joint evolution of behavioral and life history traits.
Received: 6 March 1996 /Accepted after revision: 12 August 1996 相似文献
6.
Laboratory observations on spawning,brood size and egg hatchability of the Antarctic krill Euphausia superba from Prydz Bay,Antarctica 总被引:1,自引:0,他引:1
Forty-three female Euphausia superba were collected from three sites in Prydz Bay, Antarctica in January 1985. Most gravid females took 3 to 14 d to spawn after capture and some less mature females released eggs after 21 d. Most females spawned only once; overall mean brood size was 2 809 eggs and mean hatchability for eggs from the premoult females was 69.7%. For seven females spawning a second time, overall mean brood size was 597 eggs. Mean hatchability for second-spawn eggs from five premoult females was 67.1%. Possible origins of the second-spawned eggs were small numbers of matured eggs left in the ovaries after the first spawning or eggs developed from those of peripheral nucleolus and vitellogenic stages. Throughout the 8 wk of observations, there was no apparent development of eggs in females which had released all their eggs at one spawning. 相似文献
7.
Greg W. Rouse Nerida G. Wilson Shana K. Goffredi Shannon B. Johnson Tracey Smart Chad Widmer Craig M. Young Robert C. Vrijenhoek 《Marine Biology》2009,156(3):395-405
We report observations on spawning and early development in bone-eating worms of the genus Osedax. Individual females of Osedax rubiplumus were observed at 1820 m depth freely spawning hundreds of oocytes, and females of an undescribed species, Osedax “orange collar”, were observed spawning in laboratory aquaria. Cytological and molecular analysis of the spawned oocytes
of two Osedax species revealed no evidence for the bacterial endosymbionts that the female worms require for their nutrition, suggesting
that the bacteria must be acquired later from the environment, as they are in other siboglinids. Individual O. “orange collar” females released an average of 335 (±130) eggs per day, but the number of oocytes spawned per day varied
greatly, suggesting that not all the females spawned daily. Fertilization rates of the spawned oocytes varied from 0 to 100%,
though most females showed nearly 100% fertilization rates. Oocytes spawned in the laboratory at 4–6°C were negatively buoyant.
If fertilized, these oocytes extruded polar bodies and then after at least four hours cleaved unequally. Subsequent cleavages
occurred in a spiral pattern at roughly 2-h intervals, resulting in free-swimming trochophore larvae after 24 h. These lecithotrophic
trochophores swam for 9–16 days before settling with several hooked chaetae, similar to those of dwarf Osedax males. The larval life span of the Osedax species studied in the laboratory appears to be shorter than in closely related Vestimentifera. Osedax rubiplumus, on the other hand, has much larger oocytes and so may have greater dispersal potential than these other Osedax species. The high fecundity and apparently continuous reproduction of Osedax boneworms permits the opportunistic exploitation of sunken vertebrate bones.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
8.
Developing eggs and larvae of laboratory-reared gilthead sea bream (Sparus aurata) maintained in filtered seawater (40 ppt) at 18°C, were measured for oxygen uptake, ammonia excretion, contents of free amino acids (FAA), protein, fatty acids (FA) accumulated ammonia, and volumes of yolk-sac and oil globule. Absorption of the yolk coincided with the consumption of FAA and was complete ca. 100 h post-fertilisation. Amino acids from protein were mobilised for energy in the last part of the yolk-sac stage. Absorption of the oil globule occurred primarily after hatching following yolk absorption, and correlated with catabolism of the FA neutral lipids. Overall, FAA appear to be a significant energy substrate during the egg stage (60 to 70%) while FA from neutral lipids derived from the oil globule are the main metabolic fuel after hatching (80 to 90%). 相似文献
9.
S. C. Surey-Gent 《Marine Biology》1981,62(2-3):157-160
The juveniles, non-gravid females, gravid females and males of the free-living marine nematode Anoplostoma viviparum Bastian showed markedly different distributions within layers of mud from Southampton Water sampled during the early spring of 1975. Of the total population, 92% of gravid females occurred in the anoxic layer, 73% of juveniles occurred in the flocculant layer, non-gravid females and males were found in approximately equal numbers in both the flocculant and oxidised layers but none in the anoxic layer. A tentative activity cycle based on these distributions is put forward for consideration, taking into account the water movement within the estuary. 相似文献
10.
The transfer of chlorinated hydrocarbons (CHC) in a laboratory simulation of a three trophic level marine food chain was studied. The food chain consisted of the algal flagellate Dunaliella sp., the rotifer Brachionus plicatilis, and the larva of the Northern anchovy Engraulis mordax. CHC were introduced into the seawater at concentrations representative of near-shore conditions off southern California without the use of dispersing agents. Each trophic level appeared to be in a steady-state at the time of first sampling, 5 days after inoculation. Apparent partition coefficients were calculated for each trophic level. The CHC contamination in the diet of the rotifers and anchovy larvae was also calculated. Unfed anchovy larvae accumulated the same amount of CHC as fed larvae and the final concentration appeared to be dependent on the CHC concentration in the seawater. The data in this report suggest that CHC accumulation is not a food-chain phenomenon but rather the result of direct partitioning of the compounds between the seawater and the test organisms. 相似文献
11.
Birgitta Sillén-Tullberg 《Behavioral ecology and sociobiology》1981,9(4):283-289
Summary Copulation in Lygaeus equestris L. (Heteroptera, Lygaeidae) is known to last 0.5–24 h. Variations in copula duration of field-collected insects were studied in the laboratory, and different hypotheses concerning the significance of prolonged copulations were tested.Through reciprocal matings with normal and sterile (irradiated) males, sperm displacement was estimated at about 90%. A male could thus increase his fitness by preventing subsequent matings of an inseminated female.Copulations with virgin insects, observed over 15 h, were classified in two categories: short (0.5–8.0 h) and long (> 15 h) duration (Fig. 1). No difference in the number of fertilized eggs was found between long and short copulations, and the insemination rate was highest during the first hour of a couplation (Fig. 2). Long-lasting couplations did not give rise to increased sperm displacement (Table 2). These results indicate that there is no difference in the amount of sperm transferred during short and long copulations and that no insemination takes place during the latter part of a prolonged copulation.Longer lasting copulations occurred when the sex ratio was male-biased than when it was female-biased (Fig. 1). The frequency of prolonged copulations was higher when the female was gravid than when she contained no eggs (virgin) (Figs. 3 and 4). Support is thus given to the hypothesis that prolonged copulation is a male postinsemination strategy to prevent subsequent matings of a female.Females subjected to male competition over a longer period, laid fewer eggs and died earlier than females that were mated but subsequently isolated from males (Fig. 5). Egg batches from females living with males were larger than batches from mated, isolated females (Table 3). This is probably due to a combination of many matings with short intermissions and prolonged copulations, both of which postpone oviposition.Comparisons between copulations of males with either gravid or virgin females during these experiments, led to the conclusion that short copulations with virgin females result from a male decision to terminate copulation after insemination is completed, whereas copula duration with gravid females is more likely to depend on a combination of male and female behavior. 相似文献
12.
L. M. Warren 《Marine Biology》1976,38(3):209-216
A population of Capitella capitata (Fabricius) was sampled from January, 1973 to February, 1974. Size of the worms was measured and sexual maturity determined. There is an extensive breeding season, spawning occurring asynchronously throughout the year. Females containing ripe oocytes were almost always present, but most females at any one time contained immature oocytes. A high percentage of males contained active sperm. Oocytes are not released into the coelomic fluid until almost fully developed, and all are released at a single spawning. A large number of eggs are produced at each spawning and there is some evidence to suggest that larval development may be completely benthonic. Gametes first develop in 7 to 8 month old worms and take about 4 months to complete development. Analyses of the female population structure suggests that there are 3 breeding classes. The growth rate is estimated at 30 mm per year, and few worms are believed to survive longer than 2 years. 相似文献
13.
McCormick MI 《Ecology》2006,87(5):1104-1109
Most marine populations are sustained by the entry of juveniles that have survived the larval phase, during which time most die. The number of survivors depends strongly on the quality of the eggs produced by spawning females, but it is not known how the social conditions under which breeding occurs influence the quality of larvae produced. Here I show that the density of females interacting with breeding mothers directly influences the size of larvae produced, through a stress-related mechanism. On the Great Barrier Reef of Australia, breeding pairs of a damselfish, Pomacentrus amboinensis, were isolated on habitat patches, and additional females that could not access the spawning site were added at four densities (0, 1, 3, or 6 females). Additional females increased aggressive interactions by mothers and increased the levels of the stress hormone, cortisol, in their ovaries, leading to reduced larval size. Neither egg output nor yolk size of the larvae was influenced by female density. Pairs breeding in isolation produced the largest larvae; current theory suggests that these larvae should contribute most to subsequent population replenishment events. This social mechanism may influence which females effectively contribute to the next generation and may promote resilience in patchy or isolated populations. 相似文献
14.
Specimens of the intertidal crab Hemigrapsus nudus (Dana, 1851) were collected near Sitka, Alaska, in 1983, and were used in laboratory experiments to determine the influence of periodic exposure to air on the toxicity, uptake, and elimination of two aromatic hydrocarbons, toluene and naphthalene. Three tidal cycles were simulated; i.e., crabs spent 0, 33, or 66% of the time in air and the remainder of the time in toxicant or seawater solutions. Naphthalene was 10 to 20 times more toxic than toluene: naphthalene caused locomotory impairment or killed the crabs more rapidly and at concentrations lower than those of toluene. In tissues, naphthalene was accumulated faster and to higher concentrations than was toluene. Exposure to air 66% of the time reduced mortality as well as the rate at which toluene and naphthalene were accumulated and lost. Crabs exposed to air had significantly higher respiration rates than those submerged in seawater; thus, reduced rates of accumulation and loss of hydrocarbons were not caused by general metabolic quiescence. Exposure to air reduced the time the crabs were in contact with water-borne hydrocarbons and, therefore, reduced toxicity of the hydrocarbons. Once crabs had accumulated the toxicants, however, elimination was hindered by exposure to air, even for the somewhat volatile compound toluene. 相似文献
15.
Time-dependent shifts between infanticidal and parental behavior in female burying beetles a mechanism of indirect mother-offspring recognition 总被引:4,自引:0,他引:4
Summary Female burying beetles Necrophorus vespilloides Herbst (Coleoptera: Silphidae) were allowed to lay eggs on a carcass and their subsequent behavior towards larvae added to the carcass was observed. Females did not discriminate against unrelated larvae if these were added within an hour after the females' own first larva had hatched (at the right time). Changing the spatial surroundings of the carcass had no effect on the females' readiness to exhibit care behavior. Neither did the age of the larvae added or the condition of the carcass affect the onset of maternal care. However, the females' response to larvae encountered was strongly time-dependent: most females killed and ate larvae that could not have hatched from their own eggs because they were added long before their own larvae hatched. The proportion of females accepting larvae added to early increased as the time their own larvae hatched approached. Larvae added to the carcass 2 or 3 days after the test females' own first larva had hatched were always accepted by females that had already started to feed larvae, but were often killed by females that were not feeding larvae. In the latter group of females, the tendency to kill larvae added was most pronounced if the females had already started to produce a second clutch of eggs at the time larvae were added.
Offprint requests to: J.K. Müller 相似文献
16.
Larvae of the mud crab Eurypanopeus depressus (Smith) were reared in various concentrations of the water-soluble fraction of Kuwait crude oil. The 48-h TLm (median tolerance limit) for Zoea Stage I was approximately 10 ppm total dissolved hydrocarbons and that for Zoea Stage II approximately 17 ppm. Chronic toxicity of more dilute solutions (4.3 and 8.7 ppm) was assessed independently for each larval stage and for subsequent developmental stages through Crab Stage 5. In the group continuously exposed to oil from hatching, there was differential mortality relative to controls in every larval stage and increased duration of intermolt periods was observed at every stage through Crab Stage 5. Mortality in groups not exposed until larvae had reached Zoea Stages III or IV was not greater than controls, suggesting that toxicity to advanced larval stages may be related to accumulation of toxic compounds by the larvae. Neither concentration (4.3 or 8.7 ppm) of crude oil caused increased mortality among juvenile crab stages regardless of the time of initial exposure. Increased occurrence of an extra and morphologically abnormal megalopa stage was associated with exposure to the crude oil. This has not been reported before.Communicated by I. Morris, West Boothbay Harbor 相似文献
17.
Larvae of the red abalone (Haliotis rufescens Swainson) are functionally incapable of capturing particulate foods. The aim of this study was to determine whether these larvae could acquire energy from seawater in the form of dissolved organic material. Trochophore and veliger larvae were shown to acquire energy by transporting dissolved organic material from seawater. Both larval stages took up all classes of amino acids tested. The influx of radiolabeled alanine represented the net substrate flux, as determined by direct chemical measurement for both trochophore and veliger larvae. Although veliger larvae have a transport system to take up taurine from seawater, a net efflux was observed for this amino acid. The release of taurine occurred independently of the presence of either taurine or other amino acids in the medium. Transported alanine was used in both anabolic and catabolic pathways. The percent of 14C-alanine in the trichloroacetic acid-insoluble fraction (macromolecules) of veliger larvae ranged from 21 to 56% of the total radioactivity in the larvae. No lipid biosynthesis was detected from 14C-labeled alanine. Veliger larvae catabolized 15 to 19% of the total alanine taken up and released it as 14CO2. The metabolic rate (oxygen consumption) and the rate of amino acid uptake were both determined for the same group of veliger larvae. The percent contribution that the uptake of amino acids, from a total concentration of 1.6 M, made to the metabolic demand of abalone larvae ranged from 39 to 70%. Thus, these lecithotrophic larvae are not energetically independent of their environment, a result which differs from the current view of energy allocation to nonfeeding larvae.Please address all requests for reprints to Dr. Manahan at the University of Southern California 相似文献
18.
The toxicity of fenitrothion was determined in larvae (nauplii, Zoeae 1 to 3, Mysis 1 to 3), postlarvae (PL stages) and juvenile
shrimp (Penaeus japonicus Bate), in two media, seawater (SW) and diluted seawater (DSW) (1100 and 550 mosM kg−1, ≃ 37 and 19‰ S). The effects of fenitrothion on the osmoregulatory capacities (OC) of juveniles were recorded. A gill and
epipodite histopathological study was also conducted. For larvae in seawater, 24 and 48 h LC50s ranged from 32.9 μg l−1 (Zoeae 2) to 10.7 μg l−1 (Mysis 3), and from 3.9 μg l−1 (Zoeae 3) to 2.0 μg l−1 (Mysis 3), respectively; 48 and 96 h LC50s in postlarvae (PL) at the same salinity ranged from 1.8 μg l−1 (PL1) to 0.6 μg l−1 (PL5), and from 0.3 μg l−1 (PL7) to 0.4 μg l−1 (PL15). In juveniles, 96 h LC50s were 0.8 μg l−1 in seawater and 1.5 μg l−1 in diluted seawater. From hatching to juvenile stages, the overall trend was a rapid decrease (from nauplii to PL5–PL7) followed
by a slight increase (from PL7 to PL15 and juveniles) in the shrimp's ability to tolerate the insecticide. In juveniles kept
in seawater and in diluted seawater, fenitrothion decreased the osmoregulatory capacity (OC = difference between the hemolymph
osmotic pressure and the osmotic pressure of the medium) at both lethal and sublethal concentrations. This effect was time-
and dose-dependent. In SW, the decrease in hypo-OC was ˜ 25% at sublethal concentrations and ˜ 35% at the 96 h LC50. In DSW, the decrease in hyper-OC was ˜ 10 to 15% at sublethal concentrations. In SW, shrimp were able to recover their OC
in less than 48 h when transferred to water free of pesticide. In DSW, recovery at 48 h was only possible after exposure to
the lowest tested sublethal concentration. Haemocytic congestions (thrombosis) of the gills, lamellae necrosis and other alterations
of gills and epipodites (breakage of the cuticle, reduction of the hemolymph lacunae) were noted in juveniles exposed to lethal
and sublethal concentrations of fenitrothion.
Received: 7 October 1996 / Accepted: 13 November 1996 相似文献
19.
The larvae of many benthic marine invertebrates settle to form conspecific aggregations and are thought to rely on chemical cues associated with adults as indicators of habitat suitability, although the identification of inductive compounds has proven difficult. Still-water laboratory assays carried out during the summers of 1992 and 1993 with larvae of the serpulid polychaete, Hydroides dianthus (Verrill, 1873), demonstrate that unidentified water-borne compound(s) were responsible for gregarious settlement of competent larvae. Unlike inductive compounds associated with other tube-dwelling polychaetes, the settlement cue was soluble in water and was not associated with the tube, but rather with the body of live adults. In assay chambers divided by a 52-m mesh barrier, a greater percentage of larvae settled on biofilmed substrata when adult worms were present on the other side of the barrier than when adults were absent. Settlement in response to conspecific adults, live worms removed from their tubes, and amputated tentacular crowns of live worms was significantly greater than settlement in response to dead worms, empty tubes, or biofilmed slides. The settlement inducer appears to emanate from the openings of occupied tubes; settlement was greatest along the anterior two-fifths of the tube of living conspecific adults. A single adult was equally capable of eliciting a gregarious response as were five or 25 conspecifics, and newly settled juveniles began to elicit gregarious settlement after approximately 96 h. Extraction of aggregations of adult worms with organic solvents removed the inductive capacity of the tissue, and activity was found in both nonpolar and polar fractions of an extraction series. 相似文献
20.
T. J. Cowles 《Marine Biology》1983,78(1):45-51
Female copepods of the species Centropages hamatus show decreased ingestion rates and decreased egg viability when exposed to crude oil/seawater dispersions having crude oil concentrations of 10–80 ppb. However, rates of egg production were not significantly affected by these exposure levels. In addition, we found no evidence for accumulation of petroleum hydrocarbons by copepods exposed to 200 ppb of South Louisiana crude oil. The results imply that biosynthetic pathways involved in oogenesis may be influenced by sublethal concentrations of crude oil or that petroleum hydrocarbons directly affect the viability of eggs. Recruitment into field populations of copepods could be severely reduced as a consequence of exposure to low levels of physically dispersed crude oil. 相似文献