Samples of two marine bird species, European shag (
Phalacrocorax aristotelis) and common eider (
Somateria mollissima) sampled at a remote coastal site in Norway were analysed for POPs and PFCs. ...Additionally samples of common eider were analysed from two other locations in Norway, representing a gradient from “densely populated” to “remote”. The variety, concentration and distribution of lipophilic POPs in comparison to PFCs were investigated. PCBs were the dominating group of contaminants in the analysed egg samples. Shag eggs had median sumPCBs levels of 4580
ng/g l.w. in 2004. Six different PBDE congeners could be detected in the shag eggs. BDE 47 and 100 were the main contributors with 24 and 27
ng/g l.w. respectively, sumPBDEs was 90
ng/g l.w. Relatively high concentrations of chlordanes were found with a total sum of 903
ng/g l.w. Of other OCs, toxaphene 26 and 52 together (sum 657
ng/g l.w.) and HCB (165
ng/g l.w.) were contributing majorly to the egg burden. Sum HCHs were low; only 54
ng/g l.w. PFOS was the main PFC in egg, plasma and liver samples. Similar median levels of 29, 32 and 27
ng/g w.w. were observed. PFOSA, PFHxS, and PFDcA were observed additionally in all shag samples at minor concentrations with the exception of elevated levels observed in liver for PFOSA and PFDcA with median levels of 7.6 and 7.9
ng/g w.w., respectively. In common eider eggs, the POP concentrations decreased up to 1/8th along the sampled spatial gradient from suburban to remote. Of the 9 detected PFCs, PFOS dominated all samples by one order of magnitude, followed by PFOA. SumPFC concentrations were twice as high at the two fjord sites compared to the remote site. Shorter chained PFCAs like PFOA and PFNA could be detected in the eider eggs whilst being absent in shag eggs.
Metal Dynamics in an Antarctic Food Chain Nygård, Torgeir; Lie, Elisabeth; Røv, Nils ...
Marine pollution bulletin,
07/2001, Letnik:
42, Številka:
7
Journal Article
Recenzirano
The concentrations of copper, zinc, cadmium, selenium and mercury were determined in eggs, muscle, liver, kidney and stomach content of nestlings and adults of the Antarctic petrel,
Thalassoica ...antarctica, and its predator, the south polar skua,
Chataracta maccormicki, from Svarthamaren, Dronning Maud Land, Antarctica. The dominant food of the petrels is krill,
Euphausia superba. The results show relatively high levels of cadmium in krill, which is assumed to be the main reason for the high levels of cadmium in petrels and skuas. Cadmium is almost absent in eggs, but accumulates very rapidly with age in nestlings. The copper concentrations in livers of nestling petrels reach very high levels during growth. This may be seen in connection with physiological development processes. Mercury seems to be accumulated with age and between trophic levels. Among the nestlings, the mercury levels decrease with increasing age, which may be accomplished by the excretion of mercury through the growth of feathers and as a dilution effect during growth. Selenium and mercury are inversely correlated in nestlings. The levels of zinc were similar for different nestling stages and between nestlings and adults in skuas and petrels.
The phylogenetic relationships within the New and Old World hawk‐eagle assemblage (genus Spizaetus; Aves: Accipitridae) were studied using mitochondrial DNA sequences (cytochrome b, control region). ...Eighty‐four specimens representing all Spizaetus species and almost all currently distinguished subspecies as well as 11 other booted and non‐booted ‘eagle’ genera from the Neotropics, Africa, Eurasia, South Asia and Australasia (Oroaetus, Harpia, Morphnus, Lophaetus, Stephanoaetus, Hieraaetus, Aquila, Ictinaetus, Spilornis, Pithecophaga, Harpyopsis) were investigated. Although the basal branching could not be resolved, our investigations clearly indicate that hawk‐eagles represent a paraphyletic assemblage and thus their external similarities have to be ascribed to convergent evolution. The New World taxa of Spizaetus cluster together, but the South American species Oroaetus isidori appears embedded within this clade. The taxa from Southeast to East Asia form a clearly separated monophyletic group. It is further divided into two subgroups, which are also characterized by distinct juvenile plumage patterns. Spizaetus africanus, the only African representative of the genus, is found in a mixed cluster consisting of members of the genera Aquila and Hieraaetus. These findings are in accordance with previous studies of other authors based on various molecular markers and different sets of taxa, but disagree with current taxonomy. Therefore, we suggest assigning the species of the genus Spizaetus to three different genera: (1) Spizaetus (including Oroaetus isidori) in Central and South America and (2) Nisaetus for the Southeast to East Asian group. (3) The African taxon (Spizaetus africanus) is discussed to be included into the genus Aquila. Furthermore, we propose to use the former genus name Lophotriorchis Sharpe, 1874, for the monotypic species Hieraaetus kienerii, which has an isolated phylogenetic position.
Zusammenfassung
Die phylogenetischen Verwandtschaftsbeziehungen innerhalb der alt‐ und neuweltlichen Haubenadler (Gattung Spizaetus, Aves: Accipitridae) wurden mit Hilfe mitochondrialer DNA‐Sequenzen (Cytochrom b, Kontrollregion) untersucht. Diese auf 84 Individuen basierende Studie repräsentiert sämtliche Spizaetus– Arten mit fast allen gegenwärtig unterschiedenen Unterarten sowie 11 weitere ‘‘Adler’’‐Gattungen mit befiederten und unbefiederten Läufen aus der Neotropis, Aethiopis, Eurasien, Südasien und Australasien (Oroaetus, Harpia, Morphnus, Lophaetus, Stephanoaetus, Hieraaetus, Aquila, Ictinaetus, Spilornis, Pithecophaga, Harpyopsis). Obwohl die basalen Verbindungen nicht eindeutig geklärt werden konnten, zeigt die vorliegende Untersuchung, dass die Haubenadler eine paraphyletische Gruppe darstellen und daher die phänotypischen Ähnlichkeiten konvergent entstanden sind. Die neuweltlichen Spizaetus‐Taxa clustern gemeinsam, jedoch liegt die südamerikanische Art Oroaetus isidori innerhalb der Klade. Im Gegensatz dazu bilden die südostasiatischen‐Taxa eine klar abgetrennte, monophyletische Gruppe. Diese ist in zwei Untergruppen unterteilt, die auch durch verschiedene Jugendgefieder charakterisiert sind. Spizaetus africanus, der einzige afrikanische Vertreter dieser Gattung, liegt in einem gemischten Cluster bestehend aus einigen Aquila‐ und Hieraaetus‐Arten. Diese Ergebnisse stimmen mit anderen Studien, welche auf unterschiedlichen mitochondrialen Markern basieren und jeweils andere Arten umfassen, überein, stehen aber im Widerspruch zur gegenwärtigen Taxonomie. Deshalb schlagen wir vor, die Arten der Gattung Spizaetus auf drei Gattungen aufzuteilen: (1) Spizaetus (inklusive Oroaetus isidori) für die Arten aus Mittel‐ und Südamerika und (2) Nisaetus für die südost‐ostasiatische Gruppe. (3) Bezüglich des afrikanischen Taxons (Spizaetus africanus) wird eine Zuordnung in die Gattung Aquila diskutiert. Weiters empfehlen wir, für die monotypische Art Hieraaetus kienerii aufgrund ihrer isolierten Stellung den ehemals verwendeten Gattungsnamen Lophotriorchis Sharpe, 1874, wieder einzuführen.
Current and future climate alterations might impact ecological processes like timing of breeding. We used multivariate linear models to assess the importance of food availability and climate on ...timing of breeding and hatching brood size of European shags Phalacrocorax aristotelis in 2 colonies, Sklinna (65° N) and Røst (67° N), in the Norwegian Sea over 21 yr (1989 to 2009). Predictor variables were ICES abundance estimates of young saithe Pollachius virens, the staple food of shags in these colonies, the previous winter’s North Atlantic Oscillation index (wNAO), and sea surface and air temperatures. Annual population size was included to control for density-dependent effects. The best model for hatching date explained 15% (Sklinna) and 70% (Røst) of the variation and showed that shags bred earlier when 1 yr old saithe were more abundant. The model for Røst also included 2 yr old saithe and wNAO. The best model for hatching brood size explained 40% (Sklinna) and 48% (Røst) and included a positive effect of population size at both sites. The model for Røst also included a positive effect of 1 yr old saithe. Our study demonstrates that abundance of 1 yr old saithe is a key factor for the breeding performance of shags in both colonies, whereas the climate variables were of less importance. Delayed breeding and low brood size were not associated with a high population of breeders, indicating breeding performance was density-independent and that the positive relationship between breeding numbers and saithe abundance mainly reflected variation in non-breeding among established breeders.
During the austral summer of 1996/1997 we studied south polar skuas at Svarthamaren, Dronning Maud Land, Antarctica, where the world's largest known colony of Antarctic petrels is found. Our censuses ...suggested approximately 250 full-grown skuas and 140,000 breeding pairs of petrels were present. During their breeding season, skuas did not visit the open sea at least 200 km from the site; they relied entirely on prey caught and scavenged from the petrel colony. Because the site is so isolated, we asked whether the prey (petrels) had swamped the predators (skuas), or whether there was evidence that predator numbers were limited by the size of the prey population. Particularly at the end of the petrel incubation period, we found a close correspondence between the energy required by adult skuas and their chicks, ascertained from time budget studies, and the rate at which petrel eggs disappeared from the colony. This suggests that, in this closed system, the predator population was limited by the prey population, and that predator swamping was not an advantage that petrels gained by nesting in this remote location.
The diet of the Antarctic petrel Thalassoica antarctica was studied during two seasons at Svarthamaren, an inland colony in Dronning Maud Land, Antarctica, and in the pack ice off the coast of ...Svarthamaren. The most important food (wet mass) at Svarthamaren was crustaceans (67%), fish (29%) and squid (5%); however, individuals collected in the pack ice took mostly fish (87%). The prey composition and lengths of prey are comparable to what has been documented in other studies on this species. Estimates of food consumption by birds breeding at Svarthamaren (ca. 250,000 pairs) suggest that approximately 6500 tonnes of crustaceans, 2800 tonnes of fish and 435 tonnes of squid are consumed during the breeding season. The annual consumptions of these birds are estimated to be 34,100 tonnes of crustaceans, 14,700 tonnes of fish, and 2300 tonnes of squid. Satellite telemetry data indicate that Antarctic petrels from Svarthamaren may fly more than 3000km during one foraging trip, and thus may cover a huge ocean area to obtain their prey.PUBLICATION ABSTRACT
The diets of shags and cormorants were studied in Norway through analyses of regurgitated pellets. Although this method has many limitations, indications were that both species rely heavily on small ...gadoids (Gadidae) and sand eels (Ammodytidae) for food throughout their range, but also eat other fish species when available. There was considerable dietary overlap between species, despite a tendency for cormorants to eat larger fish and more benthic items than shags. Predation by shags and cormorants could be a factor limiting the recruitment of cod and saithe into what are now severely reduced, but commercially important stocks in the Norwegian and Barents Seas.
The breeding success of Puffins Fratercula arctica, and the quality and quantity of food brought to their chicks were studied at 12 colonies along the coast of Norway in 1980-1983. In the north and ...south of the country, breeding success was good while, prior to 1983, it was poor or a total failure at colonies in the central region. Evidence which suggests a direct relationship between the level of Herring Clupea harengus stocks and the breeding success of Puffins at the latter colonies is presented.
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