Marys Medicine

Cristobal.webs.uvigo.es

Author's personal copy
Environmental Pollution 158 (2010) 1275–1280 Contents lists available at ScienceDirect Environmental Pollution EROD activity and stable isotopes in seabirds to disentangle marine food webcontamination after the Prestige oil spill Alberto Velando a,*, Ignacio Munilla b, Marta Lo´pez-Alonso c, Juan Freire d, Cristobal Pe´rez a a Departamento de Ecoloxı´a e Bioloxı´a Animal, Facultade de Ciencias, Universidade de Vigo, Campus As Lagoas, 36310 Vigo, Spainb Departamento de Bota´nica, Facultade de Farmacia, Universidade de Santiago de Compostela, Santiago de Compostela, Spainc Departamento de Patoloxı´a Animal, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spaind Grupo de Recursos Marinos y Pesquerı´as Universidade da Corun˜a, A Corun˜a, SpainTwo years after Prestige oil spill, seabirds were exposed to remnant oil related to their feeding habits with consequences on delayed lethality.
In this study, we measured via surgical sampling hepatic EROD activity in yellow-legged gulls from oiled Received 24 November 2009 and unoiled colonies, 17 months after the Prestige oil spill. We also analyzed stable isotope composition Received in revised form in feathers of the biopsied gulls, in an attempt to monitor oil incorporation into marine food web. We found that yellow-legged gulls in oiled colonies were being exposed to remnant oil as shown by hepatic Accepted 22 January 2010 EROD activity levels. EROD activity was related to feeding habits of individual gulls with apparentconsequences on delayed lethality. Capture–recapture analysis of biopsied gulls suggests that the surgery technique did not affect gull survival, giving support to this technique as a monitoring tool for oil exposure assessment. Our study highlights the combination of different veterinary, toxicological and ecological methodologies as a useful approach for the monitoring of exposure to remnant oil after a large Ó 2010 Elsevier Ltd. All rights reserved.
Sub-lethal effects as a result of the incorporation of oil into the marine food web are likely to be expected in seabirds because they Large oil spills are one of the pollution events most likely to have are long-lived animals and upper trophic level consumers dramatic effects on marine ecosystem components, including (Peterson et al., 2003), and because their populations tend to seabirds (Peterson et al., 2003). Compared to other marine organ- concentrate in habitats prone to high oil exposure (Clark, 1984).
isms, seabirds appear to be at greater risk of suffering the negative Sub-lethal effects impair seabird condition, which in turn, could impacts of oil spills. Large oil spills have indeed killed huge numbers have long-term consequences in survival and reproduction (Esler of seabirds worldwide (e.g. Wiens et al., 1984; Wilhelm et al., 2007).
et al., 2000; Golet et al., 2002). Petroleum products are toxic to Seabird casualties effectively reduce the number of reproductive seabirds. Among other causes, toxic injury is due to oxidative stress individuals in populations (e.g. Velando et al., 2005a), though this and cellular damage associated with the metabolic response by effect is believed to be short-lasting (e.g. Dunnet, 1982; Votier et al., which oil contaminants are biotransformed and eliminated from 2005). Nonetheless, marine organisms can also be affected by the tissues as happens with the catalytic activity of cytochrome P450 in chronic long-term exposure to the persistent and bioaccumulative the liver (Gonzalez, 2005; Shimada, 2006; Ramos and Garcı´a, components of oil via several indirect ecosystem processes (e.g.
2007). Thus, hepatic P450 activity is currently recognized as Broman et al., 1990; Peterson et al., 2003; Velando et al., 2005b; a sensitive and fairly specific indicator of organic contaminants, Hjermann et al., 2007). Direct lethal effects on seabirds immedi- such as the polycyclic aromatic hydrocarbons (PAH) found in ately following an oil spill typically attract the greatest public and petroleum products (Woodin et al., 1997; Kammann et al., 2005).
scientific concern. In contrast, sub-lethal effects due to chronic oil P450 induction, measured by liver 7-ethoxyresorufin-O-deethylase exposure have rarely been explored (some exceptions: Trust et al., (EROD) activity, has been observed in free-living seabirds envi- 2000; Golet et al., 2002; Alonso-Alvarez et al., 2007a), though ronmentally exposed to residual oil several years after the Exxon- they have the potential to strongly impact the long-term dynamics Valdez oil spill (Trust et al., 2000; Golet et al., 2002).
of seabird populations (Peterson et al., 2003).
Here we used a combination of methodologies; including EROD activity measures in the liver tissue of live seabirds, stable isotopeanalysis and survival estimations, in an attempt to identify the * Corresponding author. Tel.: þ34 986812590; fax: þ34 986812556.
E-mail address: [email protected] (A. Velando).
likely paths of oil incorporation into marine food web after the 0269-7491/$ – see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.envpol.2010.01.029 Author's personal copy
A. Velando et al. / Environmental Pollution 158 (2010) 1275–1280 Prestige oil spill. The Prestige oil spill of Galicia (NW Spain) in 20 C, the surgical site was set up in the open field close to the breeding area.
November 2002 was one of the most recent examples of a large Anesthesia was performed using a portable isoflurane anesthetic machine and anAyre's T-piece breathing circuit. Birds were monitored with the aid of a stethoscope marine oil spill. It resulted in the release to the marine environment and a cloacal thermometer. Prior to surgery, all birds were premedicated with of approximately 60,000 tonnes of oil products in the eight months 0.4 mg/kg of butorphanol, 0.2 mg/kg of meloxicam and 100 mg/kg of oxytetracycline following the wreck, spreading pollution from Northern Portugal to applied by intramuscular injection. Anesthesia was induced with 5% isoflurane Brittany (France). The Prestige oil spill was the biggest catastrophe delivered through a face mask and maintained at 1–2% isoflurane applied with an of its type in the Eastern North Atlantic and thousands of seabirds endotracheal tube. Laparotomy was performed through a midline ventral approach.
A 2–3 cm incision, 0.5 cm caudal to the sternum, was made in the abdominal wall of died in the following months. Since incorporation of oil from the each bird. Once the liver was identified and exposed, two 3/0 catgut overlapping Prestige is currently being detected in the marine food chain (e.g.
‘guillotine' sutures were used to triangulate and isolate a wedge of tissue of the Fernandez et al., 2006; Alonso-Alvarez et al., 2007b; Martı´nez- protruding margin of the right liver lobe. Then, the hepatic tissue distal to the Go´mez et al., 2009), chronic exposure of seabirds to oil would be ligatures was excised using a scalpel blade and mild pressure was applied to the siteof incision until bleeding stopped. Afterwards, the abdominal wall was sutured in expected, as they are long lived and upper trophic level consumers.
three different layers (abdominal musculature, subcutaneous fat and skin). All tissue The best evidence on the persistence of oil in the marine ecosys- layers were sutured with a simple interrupted pattern and 3/0 PDS suture material.
tems of Galicia, for years after the Prestige spill come from breeding Apart from some mild liver bleeding in a few birds, all surgeries were uneventful and yellow-legged gulls (Larus michahellis). In this species, adults from all animals survived the procedure. After surgery, birds were allowed to recover colonies that were in the path of the oil spill consistently showed from anesthetic inside individual cloth bags during 15–20 min. Once, fully recov-ered, they were released back to the wild.
higher oil contamination levels compared to birds from unoiledcolonies (Pe´rez et al., 2008). Moreover, the presence of PAHs in the 2.3. EROD activity measurement blood of chicks from oiled colonies indicated that these pollutantswere incorporated into the marine food chain as chicks were not EROD activity was measured using a kinetic modification of the plate-based directly exposed to crude-oil, but to contaminated organisms as assay of Kennedy and Jones (1994). The liver tissue was first homogenized in 4volumes in 0.15 M KCL in a Potter Teflon homogenizer. The homogenate was part of their diets (Alonso-Alvarez et al., 2007b; Pe´rez et al., 2010).
centrifuged at 9000  g for 15 min. The supernatant was centrifuged in an ultra- In this study, we measured hepatic P450 response in yellow- centrifuge at 100,000  g for 60 min and the resulting microsomal pellet resus- legged gulls from oiled and unoiled colonies, 17 months after the pended with resuspension buffer (50 mM Tris–HCl, 1 mM EDTA, 1 mM dithiothreitol Prestige oil spill, in order to assess potential continued exposure to and 20% v/v glycerol, pH 7.4) to give a protein concentration of approximately residual oil in these high trophic level consumers. Typically, the 20 mg/ml. EROD activity was determined in duplicate in fluorescence multiwellplate reader (Synergy HT-1) at 37 C. Thus, 150 ml of sodium phosphate buffer measurement of EROD activity requires liver tissue samples pref- (50 mM, pH 8) was added to each well, that then received microsomal suspension erably collected from freshly killed animals, although alternative (10 ml) and ethoxyresorufin (50 ml of a methanol solution that was diluted 13-fold in techniques are possible (e.g. Degernes et al., 2002). In our study sodium phosphate (50 mM, pH 8.0) immediately before addition to the wells; final samples consisted on liver biopsies collected via surgical sampling.
concentration 1.0 mM). The plate was incubated at 37 C for 5 min, and reactionswere started with the addition of NADPH (25 ml of a 13.4 mM solution in sodium Moreover, besides checking the diet of breeding adults at the two phosphate butter, pH 8.0; final concentration 1.0 mM) to each reaction well. Plates colonies through pellet analysis we analyzed stable isotope were placed into the fluorescence plate reader and scanned for resorufin with composition in feathers of the biopsied gulls. Stable isotopes were a 530 nm excitation filter and 590 nm emission filter for 10 min. Microsomal protein employed in order to quantify the trophic status of individual gulls concentrations were quantified by a Lowry assay and EROD activities expressed as (reviewed in Fry, 2006) as a means to estimate the likely pathways pmol resorufin min1 mg protein1.
of oil incorporation into the marine food web. Lastly, we estimated 2.4. Stable isotope analysis and diet analyses the apparent survival of the biopsied gulls, in order to evaluate thenon-lethality of our sampling technique and the possible differ- Mantle feathers collected from biopsied gulls were cut in 1-cm pieces, they were ences in adult survival between oiled and unoiled gull colonies.
cleaned following the method used by avian isotope labs (L. I. Wassenaar personalcommunication) in a solution of chloroform:methanol (1:1) during 24 h. Afterwards,they were air dried in an air chamber during 24 h. To carry out stable isotope 2. Materials and methods analyses, 0.5–1 mg of feather vein material was cut from the same location on eachfeather. Isotope analyses were performed in the Servicios Xerais de Apoio a´ Inves- 2.1. Study sites and animals tigacio´n (SXAIN, Universidade da Corun ˜ a). C and N contents and isotope analysis Yellow-legged gulls were sampled from oiled and unoiled coasts of Galicia, northwestern Spain (Fig. 1). For biopsies, we selected two breeding colonies, Coel-leira island, located in an area that was not touched by the Prestige oil slick (unoiledcolony) and Lobeiras islands, located in the pathway of the oil spilled from thePrestige (oiled colony). These colonies were selected because they were close enoughto limit any geographic effects not related to the Prestige oil spill and because we hadpreviously found strong differences in oil exposure in yellow-legged gulls likelyrelated to the Prestige wreck (Pe´rez et al., 2008).
Ethical considerations were taken into account in the design of the study in order to avoid unnecessary harm to many animals while still eliciting a measurableresponse. In total, 20 adults (10 in each colony) were nest-trapped in 2004 whileincubating (May 19–June 5), 17 months after the Prestige wreck. Gulls were weighed and several morphometries including wing and tarsus length (1 mm) were determined to allow sexing birds by means of a discriminant function (Bosch, 1996).
In addition, mantle feathers were collected and preserved in individual envelopes.
We selected mantle feathers because they are typically moulted prior breeding (i.e.
March–April; Harris, 1971). Adults were ringed with two rings, one on each leg: a numbered metallic ring provided by the Nature Protection Agency of Spain(Direccio´n General de Conservacio´n de la Naturaleza, Ministerio de Medio Ambiente,Spain) and a plastic ring with an individual digit combination to facilitate identifi- cation from a distance.
2.2. Liver biopsy Fig. 1. Coastal areas affected by the Prestige oil spill (given in black) in northern Spainshowing the location of the unoiled (Coelleira) and the oiled (Lobeiras) study colonies.
Surgical liver biopsies were taken by a laparotomy wedge biopsy performed by (Source: Oficina Te´cnica de Vertidos Marinos, Ministerio de Educacio´n y Ciencia. http:// an avian veterinarian in a field laboratory. Since atmospheric temperature was above Author's personal copy
A. Velando et al. / Environmental Pollution 158 (2010) 1275–1280 were determined using an elemental analyzer FlashEA1112 by ThermoFinnigan activity as independent variables to circumvent collinearity. Moreover, in order to connected to an isotope ratio mass spectrophotometer DELTA plus by Finnigan MAT, avoid type II errors due to small sample size in variables with expected directional using a ConFlo II interface.
effect (oiled colony on EROD activity; oiled colony and EROD activity on survival) Relative proportions of isotopes are estimated following: were analyzed using one-tailed tests and significance levels set at 0.05, as recom-mended in studies which involve manipulations that are potentially detrimental to animals (Still, 1982). Data are expressed as mean  SE.
Atmospheric N and VPDB (Pee Dee Belemnites) were used as standards for 3.1. EROD activity isotope analysis of N and C, respectively. In marine ecosystems a step-wise enrich-ment of 15N typically occurs with each trophic level (Hobson et al., 1994). Addi- Body mass of biopsied gulls did not differ between gulls from tionally, d13C values can reveal sources of feeding, including inshore/benthic versus oiled and unolied colonies (oiled: F offshore/pelagic diet in marine habitats (Hobson et al., 1994).
1,16 ¼ 0.27, P ¼ 0.61; sex: Isotopic values in mantle feathers were compared with those in representative F1,16 ¼ 6.71, P ¼ 0.020; tarsus: F1,16 ¼ 7.93, P ¼ 0.012). Hepatic EROD preys of yellow-legged gull in Coelleira and Lobeiras, inferred from adult pellet activity ranged from 5.42 to 288.65 pmol min1 mg protein1 in remains during adult sampling. The isotopic value of prey tissues was obtained from biopsied gulls. In our study, 17 months after the spill, EROD activity our reference material at Universidade da Corun ˜ a (see Carabel et al., 2009). More- in the liver of gulls from the oiled colony more than doubled (135%) over, we carried out a taxonomical description of prey consumption based on 169freshly regurgitated pellets collected throughout the breeding season (April–June), the activity in gulls from the unoiled colony (F1,15 ¼ 12.24, of which 122 were from Lobeiras and 47 from Coelleira. The results of food analyses P ¼ 0.001; Fig. 2). Moreover, we found that females showed higher are reported here as percent frequency of occurrence of a specific food type in EROD activity compared to males in both colonies (sex: F1,15 ¼ 7.58, a pellet sample (Table 1).
P ¼ 0.015; sex*oiled: F1,14 ¼ 1.09, P ¼ 0.31, Fig. 2). Interestingly,EROD activity was negatively correlated with d13C (parameter 2.5. Estimation of survival probabilities estimate ¼ 41.43, F1,15 ¼ 5.35, P ¼ 0.035), especially in gulls fromthe oiled colony, although the interaction was not significant During the period 2004–2008, we gathered information on survival through intensive and extensive field surveys of banded gulls both at the colony and at the (d13C*oiled: F1,14 ¼ 0.81, P ¼ 0.38).
national scale. Focal colonies were intensively monitored during the breeding If the analysis was restricted to the gulls nesting in the oiled seasons of 2004–2007. Additionally, we consulted several resighting schemes in colony, we found that hepatic EROD activity was negatively and Galicia and Spain, with >2500 resightings between 2004 and 2008 of gulls ringed exponentially related to d13C (R2 ¼ 0.41, P ¼ 0.045; Fig. 3a) and d15N across Galicia, within the movement range of yellow-legged gulls (Munilla, 1997b).
Modelling survival through capture–mark–recapture techniques requires large (R2 ¼ 0.46, P ¼ 0.030; Fig. 3b). These relationships suggest a higher sample sizes, which are difficult to obtain through work such as ours. We thus exposure in those birds foraging on low trophic levels (low d15N) relied on the analysis of apparent survival, assuming that mortality occurred in and pelagic/offshore (low d13C) preys, such as the pelagic crab individuals not resighted during the 4-year period following biopsy; a reasonable Polybius henslowii, the most common prey in the diet samples assumption, given their population traits and the intensive monitoring effort (Fig. 3c; Table 1).
described above.
2.6. Statistical analyses Body condition was analyzed by a General Linear Model (GLM) with body mass The sex of the bird did not influence subsequent apparent as dependent variable, sex and colony (oiled vs unoiled) as factors and tarsus length survival after biopsy (c2 as covariate (Velando and Alonso-Alvarez, 2003). The EROD activity was analyzed by ¼ 0.97, P ¼ 0.32). In the unoiled colony 9 of a GLM, with colony and sex as factors and stable isotopes as covariates. Initially GLM 10 ringed gulls were alive for at least one year after the biopsy. In with all explanatory variables and two-way interactions were fitted and then non- contrast, the survival of biopsied gulls in the oiled colony significant interactions and main terms were dropped sequentially to simplify the (0.5  0.17) was reduced by close to a half compared with those at model. Data meet the assumptions of parametric analysis (homogeneity of variance: the unoiled colony (0.9  0.10; c2 ¼ 4.07, P ¼ 0.022). This reduction Levene's test: P > 0.08 and normality of residuals: Kolmogorov–Smirnov test:P > 0.9). Apparent survival (resighted during 4-year period after biopsies or not) was in survival was related to hepatic EROD activity (Fig. 4; c2 ¼ 3.39, analyzed using a Generalized Linear Model (GENMOD) with binomial error and log P ¼ 0.032).
link. We tested differences in survival between colonies and sex, and the relation-ship with EROD hepatic activity. Since EROD activity was highly related to colony (see results), we performed two separated analyses on survival for colony and EROD Frequencies of occurrence (%) of the main prey types found in pellets of breedingyellow-legged gulls at the two colonies studied, Coelleira (unoiled) and Lobeiras (oiled). Sample sizes are in parenthesis.
Marine invertebrates Polybius henslowii Pollicipes cornucopia Micromesistius poutassou Sardina pilchardus Trachurus trachurus Trisopterus sp.
Fig. 2. Mean (SE) hepatic EROD activity levels of yellow-legged gulls from an oiled (Lobeiras) and an unoiled (Coelleira) colony of Galicia (northwestern Spain).
Author's personal copy
A. Velando et al. / Environmental Pollution 158 (2010) 1275–1280 Fig. 3. Relationship between hepatic EROD activity and (a) stable-carbon relative abundance, d13C (b) stable-nitrogen relative abundance, d15N, in mantle feathers of yellow-leggedgulls from an oiled colony. Dashed lines represent 95% confidence limits. (c) Stable-carbon and nitrogen isotope abundance in the main prey items in the diet of the yellow-leggedgull. Circle size is proportional to overall percent prey occurrence in the dietary sample.
Our study suggests that gulls were being exposed to remnant oil 17 months after the Prestige catastrophe and validates the nonde-structive use of seabirds as biomonitors of oil pollution in the marine environment. The results indicated that liver biopsies takenin the field have a great potential as a nonlethal invasive samplecollection method in common species that allows for the moni- toring of oil exposure in high trophic level marine organisms (e.g.
seabirds). Thus, liver tissue samples taken from gulls biopsied in anoiled colony showed higher hepatic EROD activity levels thansamples from gulls biopsied in an unoiled colony. Our results also highlight how information obtained from a combination of sources, such as biomarker activity measurements, stable isotope analysis and diet sampling, can be useful to investigate the presence and the pathways of residual oil in marine food webs.
Elevated EROD activity at the oiled site could have also been caused by exposure to contaminants that did not originate with Prestige oil spill including oil from other sources, PCB's and other chlorinated compounds (e.g. Borga et al., 2007). Nevertheless,pollution assessment studies conducted before the Prestige wreckfailed to reveal differences in these and other contaminantsbetween oiled and unoiled sampling areas (Alvarez-Pin 1995; Fernandes et al., 2008). In contrast, previous studies have documented the persistence of oil in the ecosystem and the chronicexposure of yellow-legged gull populations for years after the spill Fig. 4. Mean (SE) hepatic EROD activity levels of yellow-legged gulls according to (Alonso-Alvarez et al., 2007a; Pe´rez et al., 2008). Indeed, our spatial survival estimation. Survival was estimated assuming that mortality occurred inindividuals that were not resighted during the 4-year period after biopsy.
study on seven seabird colonies found that blood samples from Author's personal copy
A. Velando et al. / Environmental Pollution 158 (2010) 1275–1280 yellow-legged gulls breeding in colonies that were in the trajectory This result agrees with previous findings on sex-specific harmful of the spill doubled in their total PAH concentrations when effects of oil pollution on gulls (Alonso-Alvarez et al., 2007a,b), and it compared to samples from unoiled colonies (Pe´rez et al., 2008). The may be due to sex-specific foraging habits (e.g. Pons, 1994) sex- cited study also found that Lobeiras was the colony most affected by related sensitivity to oil exposures due to physiological and nutri- remnant oil from the Prestige. Since blood cells are being continu- tional stress associated to egg production (e.g. Morales et al., 2009; ously produced and have a lifespan of several weeks, the presence see also Alonso-Alvarez et al., 2007b, and references therein).
of PAHs in blood cells probably indicates a recent incorporation of Importantly, sex-specific effects of oil contamination on seabirds the contaminants. In the present study, we found elevated hepatic may have important demographic consequences, such as a reduc- cytochrome P450 levels in a colony affected by this remnant oil, tion of reproductive pairs, constraining the recovery of seabird consistent with a previous study that found that gulls sampled in populations (Martı´nez-Abraı´n et al., 2006).
oiled colonies were suffering damages on vital organs (i.e. liver and In total, 90% of the gulls that were subjected to biopsy in the kidney; Alonso-Alvarez et al., 2007a). Overall, these studies sug- unoiled colony were resighted in the four subsequent years, which gested different sub-lethal effects on seabirds, associated to the is an apparent survival expected in large gulls (estimates are in the long-term exposure to oil pollutants after the Prestige oil spill.
range of 0.800–0.935 per year; e.g. Lebreton et al., 1995; Pons and The incorporation of oil into the marine food web is further Migot, 1995; Wanless et al., 1996). This result suggests that the corroborated by the presence of PAHs in the blood of gull chicks surgery technique did not affect survival of biopsied gulls. Note that from oiled colonies that were born almost two years after the spill, surgical sampling could affect reproductive performance of biop- because nestlings would have been only exposed to contaminated sied gulls, but we had no data to evaluate this possibility. Sampled organisms in the diet (Alonso-Alvarez et al., 2007a). Yellow-legged gulls did no differ in body condition between colonies. Neverthe- gulls are omnivorous top predators that feed mainly on marine less, we found that biopsied gulls in the oiled colony had reduced animals (>85% in 2004 in our sampling colonies, including fishing survival and that survival was correlated to former hepatic EROD discards, benthic and intertidal organisms) that they obtain around activity. Although these data should be interpreted with caution their breeding colonies, thus, former studies (Pe´rez et al., 2008; due to small sample sizes and to any possible interacting effects of Alonso-Alvarez et al., 2007a), revealed that yellow-legged gulls the biopsies, this result seems to suggest that continued exposure were being chronically exposed to oil incorporated in the food web.
to residual oil impaired the gulls, thus promoting delayed lethal An interesting result of this study, although based on small sample size, is that EROD activity correlated with the feeding habits of In conclusion, we found that yellow-legged gulls in oiled colo- individual gulls. Stable isotope analysis of feather samples nies have been exposed to remnant oil as shown by hepatic EROD confirmed that birds occupying lower trophic positions (low d15N) activity levels, probably due to marine invertebrate diet. Moreover, and feeding on pelagic/offshore (low d13C) preys, probably marine this study emphasized that the combination of different veterinary, invertebrates, showed high oil exposure, as indicated by increased toxicological and ecological methodologies is a useful approach for hepatic EROD activity. In the marine environment bottom sedi- the monitoring of exposure to remnant oil in the marine food web ments and subsequently, benthic invertebrates are often the final in the event of a large oil pollution pulses. In the future, monitoring destination of oil contaminants (Woodin et al., 1997). Hence, programs based on such an integrate approach are therefore invertebrate feeders are more likely to ingest oil toxins than piscivorous feeders because marine invertebrates tend to accu-mulate toxins while fishes metabolize them rapidly (Varanasi, 1989). An important invertebrate species in the diet of theyellow-legged gull is the Henslow's swimming crab, Polybius hen- We want to express our gratitude to Direccio´n Xeral de Con- slowii, a bentho-pelagic invertebrate. This species is the most servacio´n da Natureza (Xunta de Galicia), Confrarı´a de Pescadores abundant decapod crab over the continental shelf of Galicia, and it de O Vicedo, Delegacio´n da Consellerı´a de Pesca en Celeiro and the is as a characteristic and even exclusive prey of yellow-legged gull ‘‘Punta Roncadoira'' crew for logistic support. Marta Prieto Rodrı´- populations in the Iberian Atlantic (Munilla, 1997a). Through pellet guez for veterinary assistance, Carmen Dı´ez Rivera for help during analysis we confirmed that P. henslowii was the most frequent prey fieldwork and Jorge Mourin ˜ o and a great number of birdwatchers at the time of sampling; although we do not have this kind of data for sending us their sightings of the yellow-legged gulls ringed in for the period when feathers were formed (March–April). The this study. Xunta de Galicia gave working permissions and sequestration of oil products by marine invertebrates can be approved the study. I.M. was supported by a Xunta de Galicia ‘‘Parga responsible for the long-term exposure to oil contaminants in the Pondal'' fellowship contract. The present study was financed by the seabirds that ingest them, which, in turn, is likely to have long-term program Plan Nacional IþDþI (VEM2003-20052, Ministerio de population consequences (Peterson et al., 2003).
Educacio´n y Ciencia, Spain).
The high EROD activity levels observed in yellow-legged gulls after the Prestige oil spill agrees with previous findings on marine birds following the Exxon-Valdez oil spill. There, hepatic rates ofEROD activity were higher in harlequin ducks (Histrionicus histri- Alonso-Alvarez, C., Munilla, I., Lo´pez, M., Velando, A., 2007a. Sublethal toxicity of onicus), Barrow's goldeneyes (Bucephala islandica) and Pigeon the Prestige oil spill on yellow-legged gulls. Environment International 33, guillemots (Cepphus columba) from oiled sites compared to birds from unoiled sites (Trust et al., 2000; Golet et al., 2002). These Alonso-Alvarez, C., Pe´rez, C., Velando, A., 2007b. Effects of acute exposure to heavy fuel oil from the Prestige spill on a seabird. Aquatic Toxicology 84, 103–110.
results suggest that in the aftermath of large oil spills, seabirds are ˜ eiro, M.E., Simal Lozano, J., Lage Yusty, M.A., 1995. Organochlorine susceptible to continued exposure to residual oil during several compounds in mussels of the estuarine bays of Galicia (North-West Spain).
years. Thus, sub-lethal delayed effects due to continued oil Marine Pollution Bulletin 30, 484–487.
Bosch, M., 1996. Sexual size dimorphism and determination of sex in yellow-legged contamination cannot be ignored if the impact of oil pollution on gulls. Journal of Field Ornithology 67, 534–541.
seabirds is to be assessed. Indeed, sub-lethal effects could eventu- Borga, K., Hop, H., Skaare, J.U., Wolkers, H., Gabrielsen, G.W., 2007. Selective bio- ally have a stronger impact on population dynamics than direct accumulation of chlorinated pesticides and metabolites in Arctic seabirds.
Environmental Pollution 145, 545–553.
mortality (see Peterson et al., 2003). Interestingly, we also found Broman, D., Na¨f, C., Lundbergh, I., Zebu¨hr, Y., 1990. An in situ study on the distri- that females showed higher EROD activity levels in liver, than males.
bution, biotransformation and flux of polycyclic aromatic hydrocarbons (PAHs) Author's personal copy
A. Velando et al. / Environmental Pollution 158 (2010) 1275–1280 in an aquatic food chain (Seston-Mytilus edulis L.–Somateria mollissima L.) from Munilla, I., 1997a. Henslow's swimming crab (Polybius henslowii) as an important the Baltic: an ecotoxicological perspective. Environmental Toxicology and food for yellow legged gulls (Larus cachinnans) in NW Spain. ICES Journal of Chemistry 9, 429–442.
Marine Science 54, 631–634.
Carabel, C., Verı´simo, P., Freire, J., 2009. Effects of preservatives on stable isotope Munilla, I., 1997b. Desplazamientos de la Gaviota Patiamarilla (Larus cachinnans) en analyses of four marine species. Estuarine Coastal and Shelf Science 82, poblaciones del norte de la Penı´nsula Ibe´rica. Ardeola 44, 19–26.
Pe´rez, C., Velando, A., Munilla, I., Lopez-Alonso, M., Oro, D., 2008. Monitoring PAH Clark, R.B., 1984. Impact of oil pollution on seabirds. Environmental Pollution 33, pollution in the marine environment after the Prestige oil-spill by means of seabird blood analysis. Environmental Science and Technology 42, 707–713.
Degernes, L.A., Harms, C.A., Golet, G.H., Mulchay, D.M., 2002. Anaesthesia and liver Pe´rez, C., Munilla, I., Lo´pez-Alonso, M., Velando, A., 2010. Sublethal effects on seabirds biopsy techniques for pigeon guillemots suspected of exposure to crude oil in after the Prestige oil-spill are mirrored in sexual signals. Biology Letters 6, 33–35.
marine environments. Journal of American Veterinary Medical Association 16, Peterson, C.H., Rice, S.D., Short, J.W., Esler, D., Bodkin, J.L., Ballachey, B.E., Irons, D.B., 2003. Long-term ecosystem response to the Exxon Valdez oil spill. Science 302, Dunnet, G.M., 1982. Oil pollution and seabird populations. Philosophical Trans- actions Royal Society, London, Biological Sciences 297, 413–427.
Pons, J.M., 1994. Feeding strategies of male and female Herring gulls during the Esler, D., Schmutz, J.A., Jarvis, R.L., Mulcahy, D.M., 2000. Winter survival of adult breeding season under various feeding conditions. Ethology Ecology and female harlequin ducks in relation to history of contamination by the Exxon Evolution 6, 1–12.
Valdez oil spill. Journal of Wildlife Management 64, 839–847.
Pons, J.M., Migot, P., 1995. Life-history strategy of the herring gull: changes in Fernandes, D., Andreu-Sa¨nchez, O., Bebianno, M.J., Porte, C., 2008. Assessment of survival and fecundity in a population subjected to various feeding conditions.
pollution along the Northern Iberian shelf by the combined use of chemical and Journal of Animal Ecology 64, 592–599.
biochemical markers in two representative fish species. Environmental Pollu- Ramos, R., Garcı´a, E., 2007. Induction of mixed-function oxygenase system and tion 155, 327–335.
antioxidant enzymes in the coral Montastraea faveolata on acute exposure to Fernandez, N., Cesar, A., Gonzalez, M., DelValls, T.A., 2006. Level of contamination in benzo(a)pyrene. Comparative Biochemistry and Physiology – Part C 44, 348–355.
sediments affected by the Prestige oil spill and impact on the embryo devel- Shimada, T., 2006. Xenobiotic-metabolizing enzymes involved in activation and opment of the sea urchin. Ciencias Marinas 32, 421–427.
detoxification of carcinogenic polycyclic aromatic hydrocarbon. Drug Metabo- Fry, B., 2006. Stable Isotope Ecology Brian Fry. Springer, New York, NY.
lism and Pharmacology 21, 257–276.
Golet, G.H., Seiser, P.E., McGuire, A.D., Roby, D.D., Fischer, J.B., Kuletz, K.J., Irons, D.B., Still, A.W., 1982. On the numbers of subjects used in animal behaviour experiments.
Dean, T.A., Jewett, S.C., Newman, S.H., 2002. Long-term direct and indirect Animal Behaviour 30, 873–880.
effects of the Exxon Valdez oil spill on pigeon guillemots in Prince William Trust, K.A., Esler, D., Wooding, B.R., Stegeman, J.J., 2000. Cytochrome P450 1A Sound, Alaska. Marine Ecology Progress Series 241, 287–304.
induction in sea ducks inhabiting nearshore areas of Prince William Sound, Gonzalez, F.J., 2005. Role of cytochromes P450 in chemical toxicity and oxidative Alaska. Marine Pollution Bulletin 40, 397–403.
stress: studies with CYP2E1. Mutation Research 569, 101–110.
Varanasi, U. (Ed.), 1989. Metabolism of Polycyclic Aromatic Hydrocarbons in the Harris, M.P., 1971. Ecological adaptations of moult in some British gulls. Bird Study Aquatic Environment. CRC Press, Boca Raton, FL.
18, 113–118.
Velando, A., Alonso-Alvarez, C., 2003. Differential body condition regulation by Hobson, K.A., Piatt, J.F., Pitocchelli, J., 1994. Using stable isotopes to determine males and females in response to experimental manipulations of brood size and seabird trophic relationships. Journal Animal Ecology 63, 786–798.
parental effort in the blue-footed Booby. Journal Animal Ecology 72, 846–856.
Hjermann, DØ, Melsom, A., Dingsør, G.E., Durant, J.M., Eikeset, A.M., Roed, L.P., Velando, A., A´lvarez, D., Mourin ˜ o, J., Arcos, F., Barros, A., 2005a. Population trends Ottersen, G., Storvik, G., Stenseth, N.C., 2007. Fish and oil in the Lofoten–Barents and reproductive success of European Shag following the Prestige oil spill in the Sea system: synoptic review of the effect of oil spills on fish populations. Marine Iberian Peninsula. Journal of Ornithology 46, 116–120.
Ecology Progress Series 339, 283–299.
Velando, A., Munilla, I., Leyenda, P.M., 2005b. Short-term indirect effects of the Kammann, U., Lang, T., Vobach, M., Wosniok, W., 2005. Ethoxyresorufin-O-dee- Prestige oil spill on a marine top predator: changes in prey availability for thylase (EROD) activity in dab (Limanda limanda) as biomarker for marine European shags. Marine Ecology Progress Series 302, 263–274.
monitoring. Environmental Science Pollution Research 12, 140–145.
Votier, S.C., Hatchwell, B.J., Beckerman, A., McCleery, R.H., Hunter, F.M., Pellatt, J., Kennedy, S.W., Jones, S.P., 1994. Simultaneous measurement of cytochrome P4501A Trinder, M., Birkhead, T.R., 2005. Oil pollution and climate have wide-scale catalytic activity and total protein concentration with a fluorescence plate impacts on seabird demographics. Ecology Letters 8, 1157–1164.
reader. Analytical Biochemistry 222, 217–223.
Wanless, S., Harris, M.P., Calladine, J., Rothery, P., 1996. Modelling responses of Lebreton, J.-D., Morgan, B.J.T., Pradel, R., Freeman, S.N., 1995. A simultaneous herring gull and lesser black-backed gull populations to reduction of repro- survival rate analysis of dead recoveries and live recapture data. Biometrics 51, ductive output: implications for control measures. Journal of Applied Ecology 33, 1420–1443.
Martı´nez-Go´mez, C., Ferna´ndez, B., Valde´s, J., Campillo, J.A., Benedicto, J., Wilhelm, S.I., Robertson, G.J., Ryan, P.C., Schneider, D.C., 2007. Comparing an esti- Sa´nchez, F., Vethaak, A.D., 2009. Evaluation of three-year monitoring with mate of seabirds at risk to a mortality estimate from the November 2004 Terra biomarkers in fish following the Prestige oil spill (N Spain). Chemosphere 74, Nova FPSO oil spill. Marine Pollution Bulletin 54, 537–544.
Wiens, J.A., Ford, R.G., Heinemann, D., 1984. Information needs and priorities for Martı´nez-Abraı´n, A., Velando, A., Genovart, M., Gerique, C., Bartolome´, M.A., assessing the sensitivity of marine birds to oil spills. Biological Conservation 28, Villuendas, E., Sarzo, B., Oro, D., 2006. Sex-specific mortality of European shags during an oil spill: demographic implications for the recovery of colonies.
Woodin, B.R., Smolowitz, R.M., Stegeman, J.J., 1997. Induction of cytochrome P4501A Marine Ecology Progress Series 318, 271–276.
in the intertidal fish (Anoplarchus purpurescens) by Prudhoe Bay crude oil and Morales, J., Velando, A., Torres, R., 2009. Fecundity limits attractiveness when environmental induction in fish from Prince William Sound. Environmental pigments are scarce. Behavioral Ecology 20, 117–123.
Science and Technology 31, 1198–1205.

Source: http://cristobal.webs.uvigo.es/papers/8.EROD%20activity%20and%20stable%20isotopes%20in%20seabirds%20to%20disentangle%20marine%20food%20web%20contamination%20after%20the%20Prestige%20oil%20spill.pdf