Fermeture de la BCU-Centrale suite au déménagement: 4 juillet – 16 août : La BCU-Centrale est fermée pour déménagement. Les commandes en magasins ainsi que les demandes de prêt entre bibliothèques ne seront pas possibles.
17 août : Réouverture de la BCU à Beauregard (rue de la Carrière 22)
Hors campus: Membres de la communauté universitaire ou de la HES-SO: n'oubliez pas d'utiliser le VPN de votre institution pour bénéficier de tous les accès.
Titre: Using Ships of Opportunity to Assess Winter Habitat Associations of Seabirds in Subarctic Coastal Alaska Auteur:Dawson, Neil M; Bishop, Mary A; Kuletz, Kathy J; Zuur, Alain F Sujet:Prince William Sound ; Brachyramphus Marmoratus ; Uria Aalge ; Rissa Tridactyla ; Non-Breeding Season Description:
Abstract In subarctic waters winter may be the period during which seabirds face the greatest environmental and physiological pressures, yet seabird distribution during this time is poorly understood. Using at-sea surveys conducted in Prince William Sound, Alaska on research ships of opportunity from November 2007 to March 2009, we investigated how seabird abundance and distribution vary within and between winters for three common seabird species with extensive ranges: common murre (Uria aalge), marbled murrelet (Brachyramphus marmoratus), and black-legged kittiwake (Rissa tridactyla). Due to a large proportion of zeros in the survey data, hurdle models were performed using generalized additive mixed models. Across the two winters, consistent temporal patterns in density and distribution were observed for all species. Common murre and marbled murrelet both increased in number in midwinter, while black-legged kittiwake decreased to very low numbers. Habitat association models revealed that common murre favored relatively protected waters while marbled murrelet favored inside bays and passages (which make up 45% of semi-protected waters) and areas of higher sea surface temperatures. Our results suggest that winter storms influenced seabird distribution, particularly in midwinter when temperatures were lowest and storms more frequent. This influence was greater than variables providing proxies for foraging opportunities, which were absent from selected models. Our study highlights the importance of considering species-specific temporal patterns throughout the non-breeding season to guide marine spatial planning that will fully address seabird conservation issues.
Fait partie de:
Northwest Science, 2015, Vol.89(2), p.111-128
0029-344X (ISSN); 10.3955/046.089.0203 (DOI)
Titre: Food limitation in epibenthic species in temperate intertidal systems in summer: analysis of 0-group plaice Auteur:Van Der Veer, Henk W.; Freitas, Vânia; Koot, Joris; Witte, Johannes Ij.; Zuur, Alain F. Description:
ABSTRACT: The Balgzand intertidal is an important nursery area for early life stages of various epibenthic crustacean and fish species. Especially in summer, extremely high numbers of individuals occur. This study analyses whether these high densities in summer lead to food limitation using 0-group plaice Pleuronectes platessa L. as a model species. Between 1975 and 2007, this species was quantitatively monitored during 20 yr. The aim of this study is twofold: (1) a statistical analysis of field growth in relation to density, whereby negative density-dependent growth is considered as an indication of intraspecific competition, and (2) a comparison of observed field growth with predicted maximum growth according to the dynamic energy budget (DEB) model, to detect whether growth reduction occurs during the growing season as an indication of interspecies competition. The statistical analysis indicated no negative density-dependent growth during the whole growing season, suggesting the absence of intraspecies competition for food. The comparison of observed growth with DEB-predicted maximum growth showed that field growth was lower than the possible maximum, and that the difference increased over time until about the end of July, suggesting interspecies competition for food in summer. The stabilization in growth rate from July onwards might be related to a change in food quality: a shift from small bivalve siphons as main food items to larger tail tips of the lugworm Arenicola marina . These findings illustrate that not only food quantity but also food quality affects growth rates, at least in 0-group plaice.
Fait partie de:
Marine Ecology Progress Series, 2010, Vol.416, pp.215-227
01718630 (ISSN); 16161599 (E-ISSN)