Biological effects of oil on early development of the Baltic herring Clupea harengus membras

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.     

Effects of exposure to sublethal concentrations of crude oil on the copepod Centropages hamatus

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.     

Hatching and viability of copepod eggs at two stages of embryological development: anoxic/hypoxic effect

The effects of low oxygen concentrations on the hatching and viability of copepod eggs at two stages of embryological development were investigated. Fully developed eggs from Acartia tonsa (Dana) and Labidocera aestiva (Wheeler) collected between July and September 1991 at Turkey Point, Florida, USA, hatched at lower oxygen concentrations than newly spawned eggs given the same incubation periods. Since many of the newly spawned eggs subsequently hatched when exposed to normoxic conditions, it is likely that the exposure to low oxygen delayed embryonic development. At oxygen concentrations where no initial hatching occurred, the subsequent hatching success of fully developed eggs of A. tonsa was higher than that of newly spawned eggs, indicating that newly spawned eggs were more sensitive to low oxygen concentrations. No such difference was observed for the eggs of L. aestiva.     

Biochemical composition of the blue crab Callinectes sapidus exposed to the water-soluble fraction of crude oil

The biochemical composition of juvenile blue crabs, Callinectes sapidus, exposed to sublethal concentrations of the water-soluble fraction of South Louisiana crude oil (0 to 2 504 ppb) for 21 d were examined. Although growth took place in all crabs, tissue content varied inversely with exposure concentration while percentage tissue water varied directly with exposure concentration. Total protein, lipid and RNA content of crabs exposed to crude oil were significantly less than that of control crabs by Day 21. DNA content was not significantly different from that of control crabs, suggesting that the difference in tissue content was due to differences in cell volume and not cell number. There were no consistent differences in the concentration of the major biochemical components, indicating that the relative contribution of each of the components remained stable during the period of sublethal stress. Ratios of RNA:DNA and protein:DNA decreased in exposed crabs and were positively correlated with scope for growth and observed growth. The ratios may be useful as indirect indicators of physiological condition. Analysis of lipid classes indicated that structural lipids in stressed crabs were less affected than were lipids used for energy storage. The changes in biochemical composition suggest that the pattern of energy utilization was altered in crabs exposed to crude oil. Growth in size without comparable growth in tissue resulted in decreased tissue content. Available energy was used for growth, with little being stored in lipid reserves.     

Colonization of meiobenthos in oil-contaminated subtidal sands in the lower Chesapeake Bay

In-situ manipulative experiments were conducted over a 3-month period (May–August 1980) to examine the rate at which meiobenthos colonizes oiled and untreated azoic fine sands at a shallow subtidal site in the lower York River, Virginia. Three concentrations of fresh Prudhoe Bay crude oil were added to sediments: 100, 2 500 and 10000 mg oil kg^-1 dry wt sediment. Untreated azoic and natural sediments served as controls. Within 16 d, meiofauna densities in all treatments were comparable to natural populations in surface oxidized sediments, but densities fluctuated greatly during the remainder of the sampling period. Nematodes slowly colonized the subsurface anoxic sediments below the redox potential discontinuity (RPD); some less common species did not significantly recover below the RPD in the two more heavily oiled treatments. Analysis of nematode community composition by reciprocal averaging ordination and numerical classification revealed generally lower abundances, but no distinct differences, in species composition in the oiled substrates as compared to untreated and natural community controls. Ordination of sequential samples suggested that the nematode species assemblages in the untreated controls fully recovered from these small-scale disturbances by 90 d. Life history characteritics and frequent tidal transport combine to make estuarine meiobenthos highly resilient following disturbance. Contrary to prior recolonization studies, a successional sequence was found for the colonizing nematodes which may be analogous to models of macrobenthic colonization (e.g. McCall, 1975). The comesomatid nematode Sabatieria pulchra, which is frequently dominant in polluted sediments, colonized relatively late in the experiment. Consequently, stress resistance and resilience may not be as coincident in meiofauna as in macrofauna because of differences in factors affecting their dispersal.     

Microbial and environmental effects on avian egg viability: do tropical mechanisms act in a temperate environment?

The viability of freshly laid avian eggs declines after several days of exposure to ambient temperatures above physiological zero, and declines occur faster in tropical than temperate ecosystems. Microbial infection during preincubation exposure has recently been shown as a second cause of egg viability decline in the tropics, but whether microbial processes influence the viability of wild bird eggs in temperate ecosystems is unknown. We determined the microbial load on eggshells, the incidence of microbial penetration of egg contents, and changes in the viability of wild bird eggs (Sialia mexicana, Tachycineta bicolor, Tachycineta thalassina) experimentally exposed to temperate-zone ambient conditions in situ in a mediterranean climate in northern California. Initial microbial loads on eggshells were generally low, although they were significantly higher on eggs laid in old boxes than in new boxes. Eggshell microbial loads did not increase with exposure to ambient conditions, were not reduced by twice-daily disinfection with alcohol, and were unaffected by parental incubation. The rate of microbial penetration into egg contents was low and unaffected by the duration of exposure. Nevertheless, egg viability declined very gradually and significantly with exposure duration, and the rate of decline differed among species. In contrast to studies performed in the tropics, we found little evidence that temperature or microbial mechanisms of egg viability decline were important at our temperate-zone site; neither temperatures above physiological zero nor alcohol disinfection was significantly related to hatching success. Delaying the onset of incubation until the penultimate or last egg of a clutch at our study site may maintain hatching synchrony without a large trade-off in egg viability. These results provide insight into the environmental mechanisms that may be responsible for large-scale latitudinal patterns in avian clutch size and hatching asynchrony.     

Biliverdin-based egg coloration is enhanced by carotenoid supplementation

Avian eggshell color is remarkably variable among and within species and its possible function has long been controversial. Female birds use biliverdin pigment to color their eggs blue and green. Although evidence is accumulating that blue-green eggshell coloration is costly to produce, the exact mechanisms underlying its expression are little studied. Biliverdin pigment is involved in important maintenance functions such as immune and antioxidant defenses and shows similar properties to carotenoid pigments. Carotenoids play a role as immunoenhancers and have the potential to ameliorate the impact of oxidative processes, although their antioxidant function could be minor for some bird species. Important life-history components can be limited by carotenoid availability, including sexual displays and fecundity. Here we explored if biliverdin-based eggshell pigmentation was affected by carotenoid availability in a seabird, by performing a carotenoid supplementation experiment in female blue-footed boobies (Sula nebouxii) after laying their first egg. In this species, blue eggshell color is associated with incubation patterns, and carotenoid availability affects the crucial trade-off between female foot ornamentation and fecundity. We found that under natural conditions, there was a decline in eggshell color with laying order, suggesting pigment limitation for females. However, carotenoid-supplemented females had enhanced second egg coloration compared to controls, and the color increase was independent of their previous pigment allocation to the first egg. Our results suggest that biliverdin-based eggshell coloration is costly to produce and can be alleviated by current carotenoid availability.     

Otolith size-at-hatch reveals embryonic oxygen consumption in the zebrafish, <Emphasis Type="Italic">Danio rerio</Emphasis>

Otoliths have frequently been used to reconstruct growth histories in larval, juvenile and adult fish. However, there is growing evidence that otolith growth is directly determined by metabolic intensity and, consequently, only indirectly related to somatic growth. By performing measurements of oxygen consumption rate and other early life-history traits on individual eggs of zebrafish (Danio rerio), we found that oxygen consumption explained residual variance in otolith size that is not accounted for by egg size. Total oxygen consumption during the embryonic stage explained 34% of the variance in sagitta size at hatch, whereas larval size at hatch (as a proxy for growth during the embryonic period) was not significantly correlated with sagitta size. This strongly suggests that otolith growth is directly related to metabolic rate, and yields a mechanism that may explain recent observations of a link between otolith size at hatch and viability in larval fish.     

草甘膦铵盐暴露对乌龟胚胎发育、孵出幼体运动及学习表现的影响

草甘膦暴露可能对某些水生动物具有致死及亚致死毒性,但未见有涉及龟鳖类动物的行为毒理学的研究报道。用不同浓度草甘膦铵盐处理孵化中的乌龟卵来检测草甘膦暴露对其胚胎发育、孵出幼体大小、翻身能力以及空间学习能力的影响。结果表明,2～2 000 mg·L~(-1)浓度范围内的草甘膦铵盐暴露并不会影响乌龟卵孵化成功率、胚胎发育速率以及孵出个体的体质量和翻身时间,但对孵出幼体的空间学习能力产生一定影响。较高浓度的草甘膦铵盐暴露会导致孵出幼体的觅食时间延长、觅食过程中的运动距离增大。因此,胚胎期草甘膦铵盐暴露可能对乌龟孵出幼体的后续生长和存活有一定的负面效应。     

Effects of anoxia on the viability of subitaneous eggs of planktonic copepods

The effect of anoxia on the viability (as evidenced by hatching) of newly spawned and fully developed subitaneous eggs of three species of copepods, Acartia tonsa (Dana), Centropages hamatus (Lilljeborg), and Labidocera aestiva (Wheeler) was determined for eggs produced in the laboratory by adults collected from inshore waters of the northeastern Gulf of Mexico between January and August 1992. Hatching success decreased to 50% or less when eggs were exposed to oxygen concentrations <0.06 mll^-1 for more than 12 d, except for newly spawned eggs of L. aestiva, which still showed 50% survival after 32 d of exposure to anoxia. For all three species, newly spawned eggs survived exposure to anoxia longer than fully developed eggs. The results indicate that the increasing occurrence of anoxia in estuarine and coastal waters could have a major impact on the population growth of these important food web organisms.     

Sediment preferences and oil contamination in the Pacific sand lance Ammodytes hexapterus

Sand lance, Ammodytes hexapterus Pallas, forage for zooplankton in the water column and are under heavy predation from fish, marine birds and marine mammals. To avoid predation, these fish bury themselves in soft bottom sediments when not foraging and during overwintering. We collected sand lance in Sequim Bay, Washington State, USA, in 1982. In three experiments we presented the fish with: (1) four different sediment types (fine sand, coarse sand, gravel, silt) to determine their sediment preferences; (2) clean and oil-contaminated preferred sediment to determine whether the fish would avoid the contamination; and (3) clean unpreferred and oil-contaminated preferred sediment to determine whether the contamination would alter their sediment preferences. In the first experiment, sand lance preferred to bury in fine and coarse sands and avoided gravel and silt. In the second experiment, sand lance avoided sand contaminated with Prudhoe Bay crude oil (116 and 1050 ppm). In the third experiment, sand lance avoided the oiled sand (131 and 1041 ppm) and buried in clean gravel, and also avoided both oiled sand (113 and 1004 ppm) and clean silt, and chose to remain in the water column. The sediment particle size and the way it affects water flow through the sediment seemed to be responsible for the preferences. We suggest that the sediment type, the sediment distribution, the nutritional state of the fish, and the predation pressure influence how sand lance use the sediment as a refuge and how they respond to contamination of that refuge.Contribution No. 1392 of the School of Oceanography, University of Washington     

Uptake and Dupuration of Petroleum Hydrocarbons By the Backwater Clam, Meretrix Casta Chemnitz

Meretrix casta were experimentally exposed to water soluble fractions of refined and crude oil and their rate of accumulation of the petroleum hydrocarbons including total and individual aromatics viz., naphthalene, methylnaphthalene and dimethylnaphthalene, was studied. Subsequent transfer to clean waters in the laboratory and field resulted in depuration of the accumulated hydrocarbons from tissues. in general, the rate of discharge was found to be dependent on the concentration that the animals had been earlier exposed to and also the alkylation of aromatic hydrocarbons. Occasional increases were observed in the hydrocarbon values of clams which were placed in the field, compared to their laboratory counterparts, suggesting an intermittent source of petroleum hydrocarbon input into the environment. the influence on the rate of uptake, release and retention of hydrocarbons in the clams is discussed.     

Uptake and Dupuration of Petroleum Hydrocarbons By the Backwater Clam,Meretrix Casta Chemnitz

Meretrix casta were experimentally exposed to water soluble fractions of refined and crude oil and their rate of accumulation of the petroleum hydrocarbons including total and individual aromatics viz., naphthalene, methylnaphthalene and dimethylnaphthalene, was studied. Subsequent transfer to clean waters in the laboratory and field resulted in depuration of the accumulated hydrocarbons from tissues. in general, the rate of discharge was found to be dependent on the concentration that the animals had been earlier exposed to and also the alkylation of aromatic hydrocarbons. Occasional increases were observed in the hydrocarbon values of clams which were placed in the field, compared to their laboratory counterparts, suggesting an intermittent source of petroleum hydrocarbon input into the environment. the influence on the rate of uptake, release and retention of hydrocarbons in the clams is discussed.     

Recovery of benthic communities at Macquarie Island (sub-Antarctic) following a small oil spill

Intertidal communities at Macquarie Island (sub-Antarctic) were re-evaluated seven years after a small oil spill resulting from the grounding of the “Nella Dan”, and six years after the first assessment of biological impact. Sampling was conducted to evaluate community structure in three zones of the exposed rocky shore (upper red, kelp, and lower red) and in samples of Durvillaea antarctica holdfasts. There were no significant differences between the community structure in oiled and control locations in any of the three shore zones, but holdfast macrofaunal communities at oiled sites still showed evidence of impact. Holdfast community-structure in samples from heavily oiled sites showed moderate levels of recovery, with increased abundances of species which were considered sensitive to the oiling in the first post-impact studies and decreased abundances of opportunistic polychaete and oligochaete worms. In contrast, samples collected from the moderately oiled location at Secluded Bay showed little evidence of recovery. Holdfasts at this site were filled with sediment containing traces of diesel oil, and the macrofaunal community was dominated by opportunistic worms. This study clearly indicates that even small incidents of anthropogenic perturbation can have long-lasting consequences for marine communities at Macquarie Island. Received: 23 July 1997 / Accepted: 5 February 1998     

Accumulation of cadmium by larvae and adults of an Hawaiian bivalve,Isognomon californicum,during chronic exposure

Larvae and adults of an Hawaiian bivalve, Isognomon californicum, were exposed to sublethal, environmentally realistic concentrations of cadmium (2 and 20 ppb) for 28 d, and the accumulation of cadmium was evaluated. The concentrations of cadmium were expressed in terms of total cadmium (tissue and shell concentrations combined) and tissue cadmium. The accumulation rates of larvae were one to two orders of magnitude greater than adult rates. This study suggests that the faster uptake rates of larvae may explain why larvae are more sensitive than adults. Furthermore, the magnitude of differences between larval and adult accumulation rates may be related to metabolic rate. When larvae and adults were exposed to cadmium for only 14 d, followed by a 14 d depuration period, a substantial loss of cadmium was observed during the depuration period. Possible accumulation mechanisms and their similarity between larvae and adults are discussed.     

Effect of temperature on viability and axial muscle development in embryos and yolk sac larvae of the Northeast Arctic cod (Gadus morhua)

Cod (Gadus morhua L.) eggs may develop and hatch within temperatures of −1.5 to 12 °C, but little is known about the effects of very low temperatures on larval characteristics. Eggs of the Northeast Arctic cod (Gadus morhua) were incubated at 1, 5 or 8 °C from Day 1 after fertilisation until hatching, and transferred to 5 °C after hatching. Histological samples of the axial musculature were taken at hatching and 5 d after hatching, and the data on muscle cellularity from these samples were related to survival and hatching, size, developmental data and viability of the yolk sac larvae. All larvae hatched at the same developmental stage. Incubation of eggs at 1 °C produced shorter larvae with a larger yolk sac and more, small deep fibres at hatching than larvae from eggs incubated at 5 or 8 °C. The larval size difference was still present 5 d after hatching, a time at which the larvae from 1 °C-incubated eggs were less developed and less resistant to an acute viability stress test (65 ppt salinity). Although there were no differences between temperature groups in number and size of muscle fibres 5 d after hatching, the deep fibres of the 1 °C-group contained less myofibrils than the two other groups. The phenotype of the larvae at hatching was thus affected within these incubation temperatures. Although all groups were transferred to the same temperature after hatching, the lowest egg incubation temperature (1 °C) still had a negative effect 5 d after hatching, as these larvae were both smaller, less resistant to stress and had less functional muscles at the time of first feeding. Our conclusion is therefore that 1 °C is close to, or below, the lower thermal tolerance limit for normal functional development of Northeast Arctic cod. The results are discussed in relation to larval viability and recruitment of this species in the wild. Received: 4 February 1998 / Accepted: 10 July 1998     

Automatic sorting of zooplankton by isopycnic sedimentation in gradients of silica: Performance of a “Rho Spectrometer”

The embryonic and larval stages of the quahog clam Mercenaria sp. were exposed to the water-soluble fractions (WSFs) of 6 oils and the effects on survival and growth rate of the various stages were noted. Kuwait crude oil was the least toxic on initial exposure to both stages, having LC₅₀ values in excess of 10 ppm after continuous exposure to the WSF for up to 6 days. However, at 10 days, Kuwait was slightly more toxic than southern Louisiana crude oil, with both oils having LC₅₀ values near 2 ppm. Florida Jay crude oil was much more toxic, with an LC₅₀ of less than 1 ppm at 48 h and less than 0.2 ppm at 10 days. Two refined oils, No. 2 fuel oil and Bunker C, had LC₅₀ values of 1 to 2 ppm after 48 h, while used crankcase motor oil, the most toxic oil tested, had LC₅₀ values of 0.10 ppm or less at all exposure times. Larvae surviving exposure to water-soluble fractions of the various oils often grew at slower rates than the controls.     

Lethal and sublethal effects of naphthalene and 1,2-dimethylnaphthalene on the marine copepod <Emphasis Type="Italic">Paracartia grani</Emphasis>

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.     

Population Bottlenecks and Increased Hatching Failure in Endangered Birds

Abstract: Severe population bottlenecks are expected to lead to increases in inbreeding depression and to reduce the long‐term viability of populations. We compared hatching failure across 51 threatened bird species to test the relation between the size of population bottleneck and population viability. Bottleneck size was defined as the lowest population size recorded in a species. Hatching failure was estimated as the proportion of eggs that failed to hatch due to infertility and embryonic death, both of which increase with inbreeding. The size of the bottleneck varied from 4 to 20,000 individuals across species and had a significant negative effect on hatching failure, a pattern that was consistent when we controlled for the confounding effects of phylogeny, body size, clutch size, time since the bottleneck occurred, and latitude. Hatching failure varied from 3 to 64% across species and was more than 10% in all populations passing through bottlenecks below 100–150 individuals. Our results show that the negative consequences of bottlenecks on hatching success are widespread in the populations of species we examined, and emphasize the conservation benefit of preventing bottlenecks below 150 individuals.     

Biodegradation of crude petroleum and petroleum products by fungi isolated from two oil seeds (melon and soybean)

Crude petroleum oil degrading fungi were isolated from two oil seeds, Cucumeropsis mannii (melon) and Glycine max (soybean) seeds in the presence and absence of petroleum fumes. An assessment of the relative ability of each fungus to degrade crude petroleum, diesel and kerosene on minimum salt solution was done using change in optical density read on spectrophotometer. Twenty-one fungal species (14 genera) were isolated altogether during this experiment. These include eight species of Aspergillus; one species each of Botryodiplodia, Bipolaris, Cladosporium, Cunnighamella, Dreschlera, Fusarium, Helminthosporium, Macrophomina, Mucor, Paeciliomyces, Penicillium, Rhizopus and Talariomyces. It was evident that most of the fungi tested were able to biodegrade the crude petroleum oil, though at different rates. Bipolaris had a low rate of biodegradation of the petroleum oil of all the fungal species isolated Botryodiplodia theobromae had the highest degrading ability on the crude oil, while Aspergillus flavus had the least after 40 days of incubation. Aspergillus flavus had the highest ability to biodegrade diesel while A. niger had the least ability. In kerosene, Macrophomina phaseolina had the highest ability while A. niger had the least ability to biodegrade it. There was fluctuation in the growth pattern of the fungi in the petroleum oil medium. The implication of these are discussed.