Influence de la présence des colonies d'oiseaux migrateurs (Fulmarus glacialis et Uria lomvia) sur les assemblages benthiques de la région du détroit de Lancaster, Canada
Bibliographic record
Abstract
RESUME: Agissant en tant que vecteurs biologiques de nutriments, les oiseaux marins peuvent grandement affecter les ecosystemes terrestres, mais leur influence sur les habitats marins est encore meconnue. L'Arctique canadien abrite plusieurs millions d'oiseaux marins chaque annee durant la saison de reproduction. Par l'excretion d'importantes quantites de guano, les oiseaux marins concentrent localement de la matiere organique riche en elements nutritifs dans les zones marines entourant les colonies. Ces apports saisonniers pourraient-ils creer des points chauds de productivite biologique marine et indirectement influencer la faune benthique en augmentant la disponibilite de la nourriture (effets bottom-up)? Principalement sessiles et longevives, les especes benthiques sont capables d'integrer, a long terme, la variabilite environnementale des reseaux trophiques marins. Les objectifs de cette etude etaient de (1) caracteriser les communautes epibenthiques et endobenthiques de la region du detroit de Lancaster (LSR) et de (2) tester l'influence de la presence de colonies d'oiseaux marins et d'autres parametres environnementaux sur la structure de ces communautes benthiques. Notre hypothese etait que la diversite benthique, le nombre de taxons, la biomasse totale de l'endofaune et la densite totale de l'epifaune et de l'endofaune seraient plus eleves dans les zones avec presence de colonies. A bord du NAFC Quest en 2012, des photos du fond marin (epifaune) et des echantillons provenant d'une benne (endofaune) ont ete pris dans trois zones controles et cinq zones pres de colonies d'oiseaux marins, a une profondeur variant de 122 a 442 metres. Une base de donnees de 23 parametres environnementaux a ete construite pour etudier les liens environnement-benthos. L'endofaune, tres uniforme a travers LSR, etait dominee par les annelides en termes de densite. L'epifaune etait distribuee de facon plus heterogene, chaque zone d'etude etant unique en termes d'assemblages epibenthiques. Les ophiures etaient largement dominantes dans les communautes epibenthiques, atteignant 600 individus par metre carre. Les resultats ont egalement montre que la presence de colonies d'oiseaux marins n'etait pas un facteur structurant des communautes benthiques dans LSR a une profondeur superieure a 120 metres. Des effets negatifs des colonies ont ete observes sur la densite et le nombre de taxons de l'endofaune, ce qui pourrait etre du a des effets regulateurs par la predation (effets top-down) engendres par les oiseaux marins. Globalement, la profondeur, le type de sediment, la concentration de chlorophylle a et le nombre de jours sans glace expliquent une part substantielle de la variabilite spatiale dans la structure des communautes benthiques de LSR. Je conclus que la disponibilite de la nourriture est probablement un facteur structurant les communautes benthiques, bien que les voies de transport associees aux oiseaux marins n'affectent pas largement le benthos situe pres de la source de guano. -- Mot(s) cle(s) en francais : Communautes benthiques, Colonies d’oiseaux, Vecteur biologique, Arctique, Detroit de Lancaster, Facteurs environnementaux, Structure des communautes. -- ABSTRACT: Acting as biological vectors of nutrients, seabirds can markedly affect terrestrial ecosystems, but their influence on marine habitats is still unknown. The Canadian Arctic shelters millions of seabirds each year during the breeding season. By the excretion of important quantities of guano, seabirds locally concentrate nutrient-rich organic matter in the marine areas surrounding colonies. Could these seasonal inputs create hotspots of marine biological productivity and indirectly influence benthic fauna by increasing food availability (bottom-up effects)? Mainly sessile and long-lived, benthic species can integrate environmental variation into marine food webs over long time frames. The objectives of this study were (1) to characterize the epifaunal and infaunal communities of the Lancaster Sound region (LSR) and (2) to test the influence of the presence of seabird colonies and other environmental parameters on the structure of these benthic communities. Our hypothesis was that benthic diversity, numbers of taxa, total infauna biomass and total epifauna and infauna density would be higher in areas with presence of colonies. Aboard CFAV Quest in 2012, photos of the seafloor (epifauna) and grab samples (infauna) were taken at three control areas and at five areas near seabird colonies, within a depth range of 122 to 442 meters. A database of 23 environmental parameters was built to study the environment-benthos relationships. Infauna, which was very uniform across the LSR, was dominated by Annelida in terms of density. Epifauna was much more patchy with each study area being unique in terms of epibenthic assemblages. Brittle stars were however highly dominant in epifaunal communities, reaching 600 individuals per square meter. Results also showed that presence of seabird colonies was not a major driver of benthic communities in the LSR below 120 meters. Negative effects of colonies were detected on density and number of taxa of infauna, perhaps due to top-down effects transmitted by the seabirds. Generally, depth, sediment type, chlorophyll a concentration and duration of open water explained a substantial part of spatial variability in structure of benthic communities sampled across the LSR. I conclude that food availability is probably a factor driving benthic communities, even if potential pathways through seabirds did not broadly affect the benthos at the point source. -- Mot(s) cle(s) en anglais : Benthic communities, Seabird colonies, Biological vector, Arctic, Lancaster Sound, Environmental drivers, Community structure.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".