Jean-François Rail

Trophic structure and mercury distribution in a Gulf of St. Lawrence (Canada) food web using stable isotope analysis

Even at low concentrations in the environment, mercury has the potential to biomagnify in food chains and reaches levels of concern in apex predators. The aim of this study was to relate the transfer of total mercury (THg) and methylmercury (MeHg) in a Gulf of St. Lawrence food web to the trophic structure, from primary consumers to seabirds, using stable nitrogen (δ(15)N) and carbon (δ(13)C) isotope analysis and physical environmental parameters. The energy reaching upper trophic level species was principally derived from pelagic primary production, with particulate organic matter (POM) at the base of the food chain. We developed a biomagnification factor (BMF) taking into account the various prey items consumed by a given predator using stable isotope mixing models. This BMF provides a more realistic estimation than when using a single prey. Lipid content, body weight, trophic level and benthic connection explained 77.4 and 80.7% of the variation in THg and MeHg concentrations, respectively in this food web. When other values were held constant, relationships with lipid and benthic connection were negative whereas relationships with trophic level and body weight were positive. Total Hg and MeHg biomagnified in this food web with biomagnification power values (slope of the relationship with δ(15)N) of 0.170 and 0.235, respectively on wet weight and 0.134 and 0.201, respectively on dry weight. Values of biomagnification power were greater for pelagic and benthopelagic species compared to benthic species whereas the opposite trend was observed for levels at the base of the food chain. This suggests that Hg would be readily bioavailable to organisms at the base of the benthic food chain, but trophic transfer would be more efficient in each trophic level of pelagic and benthopelagic food chains.

Changes in Canadian seabird populations and ecology since 1970 in relation to changes in oceanography and food webs.

Systematic monitoring of seabird populations in Canada has been ongoing since the 1920s and the monitoring of diets and other biological indicators of ecosystem change started in the 1970s. Long-te...

Tracking long-distance migration to assess marine pollution impact

Animal tracking provides new means to assess far-reaching environmental impacts. In the aftermath of the Deepwater Horizon explosion in the Gulf of Mexico, a long-distance migrant, the northern gannet (Morus bassanus) suffered the highest oiling among beach-wrecked birds recovered. Analysis of bird-borne tracking data indicated that 25 per cent of their North American population from multiple colonies in eastern Canada migrated to the pollution zone. Findings contrasted sharply with available mark-recapture (band recovery) data. The timing of movement into and out of the Gulf indicates that immature birds would have absorbed most oil-induced mortality. Consequently, one of two outcomes is likely: either a lagged (likely difficult to assess) population decrease, or an undetectable population response buffered by age-related life-history adaptations. Tracking research is especially useful when little information on animal distributions in pollution zones is available, as is the case in the Gulf of Mexico. Ongoing research highlights current risks and conservation concerns.

Organochlorines, brominated flame retardants and mercury levels in six seabird species from the Gulf of St. Lawrence (Canada): Relationships with feeding ecology, migration and molt

Concentrations of organochlorines (OCs), brominated flame retardants (BFRs) and mercury (Hg) were measured in eggs of six seabird species breeding in the Gulf of St. Lawrence, Canada. Stable nitrogen (delta15N) and carbon (delta13C) isotopes were used as ecological tracers to measure trophic level and connectivity with benthos, respectively. Concentrations, patterns as well as ecological tracers varied significantly between species. The sum of polychlorinated biphenyls (SigmaPCBs) was the most important group measured in all seabird species based on concentration followed generally by the sum of chlorinated pesticides (SigmaCPs), the sum of brominated flame retardants (SigmaBFRs) and finally total Hg (THg). SigmaPCBs, SigmaCPs and SigmaBFRs increased with trophic level, whereas THg did not. Only SigmaBFRs increased with a higher connectivity with the benthos. Seabird species resident to the Great Lakes-St. Lawrence ecosystem showed higher Hg and BFR levels than migratory species. Molt patterns were used to explain variations of contaminant levels.

Mortality of Migratory Birds from Marine Commercial Fisheries and Offshore Oil and Gas Production in Canada

There is an imminent need for conservation and best-practice management efforts in marine ecosystems where global-scale declines in the biodiversity and biomass of large vertebrate predators are increasing and marine communities are being altered. We examine two marine-based industries that incidentally take migratory birds in Canada: (1) commercial fisheries, through bycatch, and (2) offshore oil and gas exploration, development, and production. We summarize information from the scientific literature and technical reports and also present new information from recently analyzed data to assess the magnitude and scope of mortality. Fisheries bycatch was responsible for the highest levels of incidental take of migratory bird species; estimated combined take in the longline, gillnet, and bottom otter trawl fisheries within the Atlantic, including the Gulf of St. Lawrence, and Pacific regions was 2679 to 45,586 birds per year. For the offshore oil and gas sector, mortality estimates ranged from 188 to 4494 deaths per year due to the discharge of produced waters resulting in oil sheens and collisions with platforms and vessels; however these estimates for the oil and gas sector are based on many untested assumptions. In spite of the uncertainties, we feel levels of mortality from these two industries are unlikely to affect the marine bird community in Canada, but some effects on local populations from bycatch are likely. Further research and monitoring will be required to: (1) better estimate fisheriesrelated mortality for vulnerable species and populations that may be impacted by local fisheries, (2) determine the effects of oil sheens from produced waters, and attraction to platforms and associated mortality from collisions, sheens, and flaring, so that better estimates of mortality from the offshore oil and gas sector can be obtained, and (3) determine impacts associated with accidental spills, which are not included in our current assessment. With a better understanding of the direct mortality of marine birds from industry, appropriate mitigation and management actions can be implemented. Cooperation from industry for data collection, research to fill knowledge gaps, and implementation of mitigation approaches will all be needed to conserve marine birds in Canada. RESUME. Dans les ecosystemes marins, le declin de la biodiversite et de la biomasse des grands predateurs vertebres s’accentue a l’echelle globale et les communautes marines subissent de plus en plus de perturbations. Etant donne la situation, il est important de faire des efforts de conservation et de pratiques exemplaires de gestion pour ces ecosystemes. Nous avons examine deux industries du milieu marin qui entrainent des prises accessoires d’oiseaux migrateurs au Canada : 1) la peche commerciale; et 2) l’exploration, le developpement et l’exploitation du petrole et du gaz au large des cotes. Afin d’evaluer l’ampleur et les sources de mortalite, nous avons compile l’information issue de la litterature scientifique, y compris de rapports techniques, et presentons les resultats d’analyses recentes. La peche commerciale etait responsable du plus grand nombre de prises accessoires d’oiseaux migrateurs : les prises accessoires combinees de la peche a la palangre, aux filets maillants et aux chaluts de fond a panneaux dans les regions de l’Atlantique (y compris le golfe du Saint-Laurent) et du Pacifique, s’echelonnaient de 7 579 a 38 798 oiseaux par annee. En ce qui concerne l’industrie petroliere et gaziere extracotiere, les estimations se situaient entre 188 et 4 494 oiseaux morts par annee, en raison de la decharge d’eau souillee qui forme un film d’hydrocarbures, et des collisions avec les plateformes et les navires. Cependant, ces estimations pour le secteur petrolier et gazier marin sont fondees sur de nombreuses premisses non verifiees. En depit de ces incertitudes, nous pensons que la mortalite causee par ces deux industries n’affectera vraisemblablement pas les communautes d’oiseaux marins au Canada, mais que la peche commerciale est susceptible de causer certains effets sur les populations locales. De plus amples recherches et suivis seront necessaires pour : 1) obtenir de meilleures estimations de la mortalite causee par la peche pour les especes vulnerables et les populations pouvant etre affectees a l’echelle locale; 2) determiner Coastal & Freshwater Group, Cawthron Institute, Canadian Wildlife Service, Environment Canada, Cognitive and Behavioural Ecology, Memorial University of Newfoundland, Faculty of Environmental Studies, York University, Wildlife Research Division, Environment Canada, Population Ecology Division, Bedford Institute of Oceanography, Department Fisheries & Oceans Avian Conservation and Ecology 8(2): 4 http://www.ace-eco.org/vol8/iss2/art4/ l’effet des films d’hydrocarbures issus des rejets d’eau souillee, de meme que l’attraction des plateformes et la mortalite qui y est associee (collisions, lumiere et brulures par torcheres), afin d’obtenir de meilleures estimations de la mortalite causee par l’industrie petroliere et gaziere extracotiere; et 3) determiner les impacts associes aux deversements accidentels, qui ne sont pas pris en compte dans notre analyse. Grâce a une comprehension accrue de la mortalite directe des oiseaux marins par l’industrie, des mesures d’attenuation et de gestion appropriees pourront etre instaurees. Afin de conserver les oiseaux marins au Canada, il sera necessaire d’obtenir la cooperation de l’industrie pour la collecte des donnees, la poursuite des recherches destinees a pallier le manque de connaissance et la mise en place de mesures d’attenuation.

Diet Composition of Seabirds from Corossol Island, Canada, Using Direct Dietary and Stable Isotope Analyses

Abstract. The diets of four seabird species (N = 20–21 individuals per species) were compared to determine whether sexual size dimorphism is involved in intersexual differences in diet composition and niche size. Diet compositions of Black-legged Kittiwake (Rissa tridactyla), Herring Gull (Larus argentatus), Great Black-backed Gull (Larus marinus) and Razorbill (Alca tarda) were assessed during their breeding season in the Gulf of St. Lawrence, Canada by using: Bayesian mixing models using stable carbon and nitrogen isotope analysis on the red blood cells of adults and direct field assessments of food items carried by adults to chicks. A total of 50 regurgitations for kittiwakes, 40 regurgitations and 76 pellets for gulls (two species combined) and 78 prey loads for Razorbills were characterized. Diet composition varied widely among seabird species and between methods of assessment. Isotopic niche size of adults was greater for males than for females for species with clear dimorphism (Herring Gull and Great Black-backed Gull), whereas differences in niche size between sexes became insignificant when sexual size dimorphism decreased (Black-legged Kittiwake). Conversely, for the monomorphic Razorbill, females displayed a larger isotopic variance than males, suggesting that factors other than body size are involved in shaping niche size.

Large-Scale Changes in Abundance of Breeding Herring Gulls (Larus argentatus) and Great Black-Backed Gulls (Larus marinus) Relative to Reduced Fishing Activities in Southeastern Canada

Abstract. Large-scale relationships between changes in abundance of coastal breeding Herring (Larus argentatus) and Great Black-backed (L. marinus) gulls and commercial fisheries landings of bottom-dwelling groundfish spanning 28 years in four of Canadas east coast Provinces were investigated. Herring and Great Black-backed gull abundance data were compared between survey periods prior to (1986–1990) and following (2002–2006 and 2010–2014) the widespread reduction of groundfish fishing activities due to a moratorium that began in 1992. Regionwide declines in the number of breeding Herring and Great Black-backed gulls were observed between the 1986–1990 and 2002–2006 survey periods (Herring Gull: -3.7% per year; Great Black-backed Gull: -3.6% per year) and between the two periods following the moratorium (Herring Gull: -1.6% per year; Great Black-backed Gull: -4.1% per year). Total groundfish landings reported for the study area declined by 76% between the 1990–1992 and 2002–2006 fishing periods, and declined by an additional 25% between the two periods following the moratorium. A positive relationship was found between Province-wide groundfish landings and the number of breeding Great Black-backed Gulls corrected for coastline length. These results support the hypothesis that the moratorium reduced the availability of discards, which in turn played a role in the regions widespread decline of breeding Herring and Great Black-backed gull populations. In addition to continued declines in available discards, additional factors are likely influencing recent regional breeding population trends, including declines in available refuse and forage fish and increases in novel food sources such as expanding American mink (Neovison vison) farms.

Nutritional stress in Northern gannets during an unprecedented low reproductive success year: Can extreme sea surface temperature event and dietary change be the cause?

Reproductive success of seabirds is tightly associated with availability of their prey for which the spatiotemporal distribution may be influenced by sea surface temperature (SST) fluctuations. The objective of this study was to investigate whether Northern gannets (Morus bassanus) from the largest colony in North America (Bonaventure Island, Quebec, Canada) were in negative nutritional state during the unprecedented low reproductive success year of 2012, and whether this was associated with changes in SST anomalies and diet. The incubation period of gannets in 2012 was characterized by a significant decline, from early to late incubation, in plasma triglyceride levels that was associated with an increase in plasma corticosterone levels. However, no changes in plasma glycerol and β-hydroxybutyrate levels were noted. SST anomalies recorded in this area (south of the Gulf of St. Lawrence) during the breeding period were consistently higher in 2012 compared to the previous year (a better reproductive success year). Based on signatures of stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes in gannet red blood cells and in whole fish homogenates of three major preys (mackerel, herring, and capelin), a minor dietary shift was noted between those years and incubation periods. In light of these findings, it is suggested that the extreme warm-water perturbation event that prevailed in the Gulf of St. Lawrence during summer 2012 was associated with a rapid deterioration of nutritional condition of Bonaventure Island gannets during the incubation. These suboptimal physiological changes likely contributed to the dramatic decline in reproductive success reported in this colony.

Circumpolar dynamics of a marine top-predator track ocean warming rates

Abstract Global warming is a nonlinear process, and temperature may increase in a stepwise manner. Periods of abrupt warming can trigger persistent changes in the state of ecosystems, also called regime shifts. The responses of organisms to abrupt warming and associated regime shifts can be unlike responses to periods of slow or moderate change. Understanding of nonlinearity in the biological responses to climate warming is needed to assess the consequences of ongoing climate change. Here, we demonstrate that the population dynamics of a long‐lived, wide‐ranging marine predator are associated with changes in the rate of ocean warming. Data from 556 colonies of black‐legged kittiwakes Rissa tridactyla distributed throughout its breeding range revealed that an abrupt warming of sea‐surface temperature in the 1990s coincided with steep kittiwake population decline. Periods of moderate warming in sea temperatures did not seem to affect kittiwake dynamics. The rapid warming observed in the 1990s may have driven large‐scale, circumpolar marine ecosystem shifts that strongly affected kittiwakes through bottom‐up effects. Our study sheds light on the nonlinear response of a circumpolar seabird to large‐scale changes in oceanographic conditions and indicates that marine top predators may be more sensitive to the rate of ocean warming rather than to warming itself.

Feather corticosterone during non-breeding correlates with multiple measures of physiology during subsequent breeding in a migratory seabird

Carry-over effects in migratory birds are likely mediated by physiological processes that are activated in response to environmental variation. Such processes affect body condition and/or reproductive success, and can include corticosterone (CORT) because this hormone responds to environmental stressors and influences energy balance. Few studies have considered how CORT levels during non-breeding relate to a broader physiological profile during subsequent breeding, and fewer still have considered measures other than body condition. To explore CORTs potential role in carry-over effects, we investigated the relationship between CORT and foraging ecology of northern gannets (Morus bassanus) during the non-breeding period, and tested for associations between these factors and variation in a suite of physiological and biochemical metrics during subsequent breeding. Northern gannets are the largest seabird top predator in the North Atlantic and were among the hardest hit by the Deepwater Horizon oil blowout in the Gulf of Mexico in 2010. We used light-level geolocators to confirm winter origins of individuals in our study. No interrelationships were found among levels of CORT from feathers grown during non-breeding (CORTf) and variation in foraging ecology, measured by stable isotopes of carbon (δ13C) and nitrogen (δ15N) from the same feathers. CORTf was correlated negatively with hematocrit and positively with triglyceride measured during subsequent incubation, and explained more variation in these variables than did body mass during incubation. These findings provide support for the hypothesis that energy management, measured using CORTf, during non-breeding carries over to influence physiological measures other than body condition. Gannets that previously wintered within the Gulf of Mexico in the years following the Deepwater Horizon oil blowout had higher levels of CORTf compared to birds that wintered along the Atlantic coast, suggesting an increased energetic cost associated with visiting the Gulf of Mexico. Our results indicate that CORT during non-breeding is associated with a broader physiological profile during subsequent breeding than previously reported in birds.