Seabirds as indicators of aquatic ecosystem conditions: a case for gathering multiple proxies of seabird health

Heavy metals in selected tissues and histopathological changes in liver and kidney of common moorhen (Gallinula chloropus) from Anzali Wetland, the south Caspian Sea, Iran

The present study aimed to measure the concentrations of Sn, Pb, Zn, Hg, Cu, Ni and Cd in the muscle and liver of 40 Common Moorhens (Gallinula chloropus) hunted from four stations in Anzali Wetland (Pirbazar, Ghalam-Koudeh, Selkeh and Abkenar). The histopathologic alteration index (HAI) of liver and kidney was also assessed in these birds. The highest concentrations of selected metals were measured in the liver of birds collected from Ghalam-Koudeh (Pb: 4.59±0.21, Sn: 6.663±0.282, Zn: 29.867±2.011, Cu: 24.07±1.84, Hg: 7.5±0.257, Ni: 6.85±0.52, Cd: 1.879±0.4mg kg(-1) dw). The lowest concentrations of metals were measured in the muscle of birds caught from Abkenar (Pb: 0.799±0.207, Sn: 1.873±0.066, Zn: 18.533±1.582, Hg: 0.86±0.08, Ni: 0.53±0.117, Cu: 6.63±1.114, Cd: 0.08±0.002mg kg(-1) dw). Also the highest and lowest concentrations of metals were recorded in sediment of Ghalam-Koudeh and Abkenar stations, respectively. These stations were located next to multi-industry Anzali Port. However, the concentration of Sn and Zn in sediment and tissues of Common Moorhens collected from different stations was lower than the permissible limit suggested by WHO and Canadian Council of Ministers of the Environment (CCME). But, Pb, Hg and Ni concentration in sediment and birds caught from all stations was higher than the permissible limit defined by WHO and CCME. Cu and Cd concentration in tissue samples and sediment of Ghalam-Koudeh and Pirbazar was also higher than the permissible limit defined by WHO and CCME. Hemorrhage, melanomacrophage aggregations, sinusoidal congestion and hepatocyte vacuolation were the most pathological changes found in the liver. Reduction of the Bowman space, melanomacrophage aggregations and hemorrhage also were observed in the kidney. The HAI means of G. chloropus collected from Ghalam-Koudeh and Pirbazar were significantly higher than other sites. Based on the HAI values and metal bioaccumulation in the tissues of G. chloropus, Ghalam-Koudeh and Pirbazar could be considered as having the worst environmental quality.

Persistent organic pollutants in forage fish prey of rhinoceros auklets breeding in Puget Sound and the northern California Current

Organochlorine contaminants in upper trophic-level consumers inhabiting Puget Sound are consistently higher than in those species inhabiting other west coast locations. We analyzed persistent organic pollutants (POPs) in the six most common fish prey of rhinoceros auklets breeding on Protection Island (Puget Sound), Tatoosh Island (WA coast), and Destruction Island (WA coast). Wet-weight concentrations of POPs ranged widely (PCBs: 1.6-25.0 ng/g; DDTs: 0.2-56.0 ng/g; PBDEs:<LOQ-49.0 ng/g), but overall patterns showed fish from Puget Sound were 2-4 times more contaminated and had similar contaminant profiles compared to fish from the outer coast. Unexpectedly elevated PCB and PBDE concentrations in Chinook salmon from the outer coast likely reflected Columbia River. Calculating contaminant loads for auklet nestlings magnified differences observed between inland and outer coast fish prey. Monitoring of breeding auklets, their prey and other resident marine birds is needed to assess biomagnification impacts in the Puget Sound marine ecosystem.

Elevated mercury levels in a wintering population of common eiders (Somateria mollissima) in the northeastern United States

In North America and Europe, sea ducks are important indicators of ecological health and inshore marine pollution. To explore spatial variation in mercury accumulation in common eiders in the northeastern United States, we compared concentrations of total mercury in common eider blood at several New England locations between 1998 and 2013. Eider food items (mollusks) were collected and analyzed to determine if mercury concentrations in eider blood were indicative of local mercury bioavailability. Eiders from Plum Island Sound, MA had a significantly higher mean blood mercury concentration (0.83 μg/g) than those in other locations. Mean mercury levels in this population were also nearly three times higher than any blood mercury concentrations reported for common eiders in published literature. We observed consistent patterns in eider blood mercury and blue mussel mercury concentrations between sites, suggesting a tentative predictive quality between the two species.

Climate change alters the trophic niche of a declining apex marine predator

Changes in the world's oceans have altered nutrient flow, and affected the viability of predator populations when prey species become unavailable. These changes are integrated into the tissues of apex predators over space and time and can be quantified using stable isotopes in the inert feathers of historical and contemporary avian specimens. We measured δ(13) C and δ(15) N values in Flesh-footed Shearwaters (Puffinus carneipes) from Western and South Australia from 1936-2011. The Flesh-footed Shearwaters more than doubled their trophic niche (from 3.91 ± 1.37 ‰(2) to 10.00 ± 1.79 ‰(2) ), and dropped an entire trophic level in 75 years (predicted δ(15) N decreased from +16.9 ‰ to + 13.5 ‰, and δ(13) C from -16.9 ‰ to -17.9 ‰) - the largest change in δ(15) N yet reported in any marine bird, suggesting a relatively rapid shift in the composition of the Indian Ocean food web, or changes in baseline δ(13) C and δ(15) N values. A stronger El Niño-Southern Oscillation results in a weaker Leeuwin Current in Western Australia, and decreased Flesh-footed Shearwater δ(13) C and δ(15) N. Current climate forecasts predict this trend to continue, leading to increased oceanic 'tropicalization' and potentially competition between Flesh-footed Shearwaters and more tropical sympatric species with expanding ranges. Flesh-footed Shearwater populations are declining, and current conservation measures aimed primarily at bycatch mitigation are not restoring populations. Widespread shifts in foraging, as shown here, may explain some of the reported decline. An improved understanding and ability to mitigate the impacts of global climactic changes is therefore critical to the long-term sustainability of this declining species.

Polychlorinated biphenyl (PCB) congener concentrations in aquatic birds. Case study: Ilha Grande Bay, Rio de Janeiro, Brazil

Livers from 108 birds found prostrate or dead in Ilha Grande Bay between 2005 and 2010 were analyzed for 16 PCB congeners (IUPAC numbers 8, 18, 28, 31, 52, 77, 101, 118, 126, 128, 138, 149, 153, 169, 170, and 180). The species analyzed were Egretta caerulea (Linnaeus 1758), Nycticorax nycticorax (Linnaeus 1758), Egretta thula (Molina 1782), and Ardea cocoi (Linnaeus 1766). The analysis were performed using Origin software (7.5, 2004) with a significant level of p<0.05. Data were checked for adherence to the standard assumptions of parametric tests using the Kolmogorov-Smirnov test for normality and the Levene's test for homogeneity of variances. This has revealed differences in concentration for some congeners. Results indicate relatively low PCBs contamination in aquatic birds, but it is implied the close relationship of environmental contamination, showing potential power of widespread biological and mutagenic adverse effects in trophic levels, and therefore, signalling risk to human health.

Ingestion of plastic marine debris by Common and Thick-billed Murres in the northwestern Atlantic from 1985 to 2012

Plastic ingestion by seabirds is a growing conservation issue, but there are few time series of plastic ingestion with large sample sizes for which one can assess temporal trends. Common and Thick-billed Murres (Uria aalge and U. lomvia) are pursuit-diving auks that are legally harvested in Newfoundland and Labrador, Canada. Here, we combined previously unpublished data on plastic ingestion (from the 1980s to the 1990s) with contemporary samples (2011-2012) to evaluate changes in murres' plastic ingestion. Approximately 7% of murres had ingested plastic, with no significant change in the frequency of ingestion among species or periods. The number of pieces of plastic/bird, and mass of plastic/bird were highest in the 1980s, lowest in the late 1990s, and intermediate in contemporary samples. Studying plastic ingestion in harvested seabird populations links harvesters to conservation and health-related issues and is a useful source of large samples for diet and plastic ingestion studies.

Application of macrobenthos functional groups to estimate the ecosystem health in a semi-enclosed bay

In this study, the functional group concept was first applied to evaluate the ecosystem health of Bohai Bay. Macrobenthos functional groups were defined according to feeding types and divided into five groups: a carnivorous group (CA), omnivorous group (OM), planktivorous group (PL), herbivorous group (HE), and detritivorous group (DE). Groups CA, DE, OM, and PL were identified, but the HE group was absent from Bohai Bay. Group DE was dominant during the study periods. The ecosystem health was assessed using a functional group evenness index. The functional group evenness values of most sampling stations were less than 0.40, indicating that the ecosystem health was deteriorated in Bohai Bay. Such deterioration could be attributed to land reclamation, industrial and sewage effluents, oil pollution, and hypersaline water discharge. This study demonstrates that the functional group concept can be applied to ecosystem health assessment in a semi-enclosed bay.

Chaos in a seasonally perturbed SIR model: avian influenza in a seabird colony as a paradigm

Seasonality is a complex force in nature that affects multiple processes in wild animal populations. In particular, seasonal variations in demographic processes may considerably affect the persistence of a pathogen in these populations. Furthermore, it has been long observed in computer simulations that under seasonal perturbations, a host-pathogen system can exhibit complex dynamics, including the transition to chaos, as the magnitude of the seasonal perturbation increases. In this paper, we develop a seasonally perturbed Susceptible-Infected-Recovered model of avian influenza in a seabird colony. Numerical simulations of the model give rise to chaotic recurrent epidemics for parameters that reflect the ecology of avian influenza in a seabird population, thereby providing a case study for chaos in a host- pathogen system. We give a computer-assisted exposition of the existence of chaos in the model using methods that are based on the concept of topological hyperbolicity. Our approach elucidates the geometry of the chaos in the phase space of the model, thereby offering a mechanism for the persistence of the infection. Finally, the methods described in this paper may be immediately extended to other infections and hosts, including humans.

High prevalence of parental delivery of plastic debris in Cory's shearwaters (Calonectris diomedea)

Plastic ingestion by adult Procellariiformes has been widely recorded, but few studies have evaluated intergenerational transfer. We assessed the prevalence of plastic particles, as well as their basic characteristics, in the gut content of dead Cory's shearwater fledglings stranded by light pollution on Canary Islands. Eighty-three percent of birds were affected, containing on average 8.0 plastic pieces per bird. The average plastic weight per bird was low (2.97±3.97mg) compared with other petrel species. We found no relationships between plastic loads and body condition or body size, but negative effects may be hidden or delayed. We propose to use the fledglings stranded by light pollution to carry out more precise studies to understand the potential hidden costs of plastic ingestion; and to monitor in a long-term the marine debris to develop management actions for the control of pollution at the marine environment.

First report of chlorinated and brominated hydrocarbon pollutants in marine bird eggs from an oceanic Indian Ocean island

We report for the first time levels of persistent organic pollutants in marine bird eggs from an oceanic island in the Indian Ocean, the world's third largest ocean. Ten eggs each of the Common Noddy, also known as the Brown Noddy (Anous stolidus), and Sooty Tern (Sterna fuscata) were collected from Ile Cocos off the coast of the island of Rodrigues, located 560 km east of the island of Mauritius. ΣPCBs had the highest levels (2.2 and 2.6n g/g wm, wet mass; 20 and 19 ng/g lm, lipid mass) for common Noddy and Sooty Tern, respectively (and following), then ΣDDT (1.9 and 3.1 ng/g wm; 17 and 23 ng/g lm), and mirex (0.96 and 0.69 ng/g wm; 8.7 and 5.0 ng/gl m). ΣChlordanes (0.094 and 0.15 ng/g wm; 0.48 and 0.73 ng/g lm) and Σtoxaphenes (0.26 and 0.61 ng/g wm; 2.4 and 5.9 ng/g lm) are rare data for these compounds from this ocean. Brominated flame retardants were low (0.08 and 0.07 ng/g wm; 0.7 and 0.7 ng/g lm). Multivariate analyses indicated different contamination patterns in the prey items as Sooty Terns had significantly higher levels of mean Σchlordanes and Σtoxaphenes, as well as CB105, -108 and -157. p,p'-DDE had an association with thinner eggshells in the Sooty Tern. Although the contaminant levels were in all respects low, industrialisation, development on the periphery, commercial exploitation of the marine environment, and pollutants transferred over long distances by marine debris is likely to add to chemical pressure in this region. Monitoring changes in background levels of pollutants in remote regions will indicate such trends, and marine bird eggs from Rodrigues would be an excellent site.

Tracking contaminants in seabirds of Arctic Canada: temporal and spatial insights

Levels and trends of persistent organic pollutants and trace elements in seabirds breeding in the vast Canadian Arctic have been monitored since 1975. Data from this monitoring have indicated both spatial and temporal variation across the region, attributable in part to differences in species' diets, differences in regional deposition patterns, and unidirectional trends in contaminants reaching this area from emissions in temperate and tropical areas to the south. Seabird tissues have served as effective biomonitors to examine this variation, and national and international collaboration in this monitoring effort has promoted valuable synthetic assessments of spatial and temporal patterns in Arctic contaminants. Here we review the history of the monitoring program, the critical role played by Environment Canada's National Wildlife Specimen Bank, and we summarize important spatial and temporal trends in various contaminants in Canadian Arctic seabirds.

DNA-based faecal dietary analysis: a comparison of qPCR and high throughput sequencing approaches

The genetic analysis of faecal material represents a relatively non-invasive way to study animal diet and has been widely adopted in ecological research. Due to the heterogeneous nature of faecal material the primary obstacle, common to all genetic approaches, is a means to dissect the constituent DNA sequences. Traditionally, bacterial cloning of PCR amplified products was employed; less common has been the use of species-specific quantitative PCR (qPCR) assays. Currently, with the advent of High-Throughput Sequencing (HTS) technologies and indexed primers it has become possible to conduct genetic audits of faecal material to a much greater depth than previously possible. To date, no studies have systematically compared the estimates obtained by HTS with that of qPCR. What are the relative strengths and weaknesses of each technique and how quantitative are deep-sequencing approaches that employ universal primers? Using the locally threatened Little Penguin (Eudyptula minor) as a model organism, it is shown here that both qPCR and HTS techniques are highly correlated and produce strikingly similar quantitative estimates of fish DNA in faecal material, with no statistical difference. By designing four species-specific fish qPCR assays and comparing the data to the same four fish in the HTS data it was possible to directly compare the strengths and weaknesses of both techniques. To obtain reproducible quantitative data one of the key, and often overlooked, steps common to both approaches is ensuring that efficient DNA isolation methods are employed and that extracts are free of inhibitors. Taken together, the methodology chosen for long-term faecal monitoring programs is largely dependent on the complexity of the prey species present and the level of accuracy that is desired. Importantly, these methods should not be thought of as mutually exclusive, as the use of both HTS and qPCR in tandem will generate datasets with the highest fidelity.

Mercury levels and health parameters in the threatened Olrog's Gull (Larus atlanticus) from Argentina

Mercury (Hg) exposure was investigated through feathers of Olrog's Gull and related to health parameters in adults (hematocrit, total plasma proteins, morphometric measures, sex) and chicks (hematocrit, total plasma proteins, immunoglobulins G and M) from a colony located in estuary of Bahía Blanca, Argentina. Mercury concentrations were 5.50 ± 2.59 μg g⁻¹ (n = 44) in live adults, 1.85 ± 0.45 μg g⁻¹ (n = 45) in live chicks and 1.81 ± 0.41 μg g⁻¹ (n = 41) in dead chicks. Large differences were observed between live adults and live or dead chicks and small differences between live and dead chicks. In the adults, the sex of the birds was the variable that best explained Hg concentrations. Male birds had higher concentrations than females; this suggests that the clutch provides a sink for mercury during egg laying. Hg concentrations in both adults and live chicks were associated with higher hematocrits. This could be associated with upregulated erythropoiesis to compensate for increased rate of destruction of prematurely senescent, Hg-contaminated erythrocytes. Based on our results, on the levels of Hg pollution in the past in the study area, and on the dietary specialization of Olrog's Gull, we must be vigilant about potential negative effects of Hg pollution on this population and recommend continued monitoring on this threatened species.

Trace metals (Cd, Cr, Cu, Fe, Ni, Pb, and Zn) in feathers of Black-browed Albatross Thalassarche melanophrys attending the Patagonian Shelf

We investigated the concentrations of cadmium, chromium, copper, iron, nickel, lead and zinc among feather tissues in sexes of Black-browed Albatross Thalassarche melanophrys killed in longliners off Argentina in 2005. We found no different metal concentration with sex for cadmium, copper, iron, lead and zinc in feathers of adult birds, though there were significant body-size differences between sexes. However, the concentrations of trace metals differed significantly among the type of feather within individual bird. The mean concentrations of copper, iron, and zinc in breast feathers of T. melanophrys were lower than those reported for the species from Georgias del Sur/South Georgia, the southern Indian Ocean and for other seabirds' worldwide. While cadmium fall within the known range of concentrations for bird feathers lead were not. Our results may be indicating that level of pollution in Patagonia may not be as negligible as previously thought at least for some trace metals.