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Macrofaunal Patterns in and around du Couedic and Bonney Submarine Canyons, South Australia.

Conlan KE, Currie DR, Dittmann S, Sorokin SJ, Hendrycks E - PLoS ONE (2015)

Bottom Line: Overall, the canyon interiors were not significantly different in community composition from the exterior (H3).However, both canyons had higher abundance and/or biomass, increased species dominance, different species composition and coarser sediments near the canyon heads compared to outside the canyons at the same depth (500 m), suggestive of heightened currents within the canyons that influence community composition there.The large number of species captured, given the relatively low sampling effort and focus on the larger macrofauna, support previous studies that identify the South Australian coast as a high biodiversity area.

View Article: PubMed Central - PubMed

Affiliation: Canadian Museum of Nature, Ottawa, Ontario, Canada.

ABSTRACT
Two South Australian canyons, one shelf-incising (du Couedic) and one slope-limited (Bonney) were compared for macrofaunal patterns on the shelf and slope that spanned three water masses. It was hypothesized that community structure would (H1) significantly differ by water mass, (H2) show significant regional differences and (H3) differ significantly between interior and exterior of each canyon. Five hundred and thirty-one species of macrofauna ≥ 1 mm were captured at 27 stations situated in depth stratified transects inside and outside the canyons from 100 to 1500 m depth. The macrofauna showed a positive relationship to depth in abundance, biomass, species richness and community composition while taxonomic distinctness and evenness remained high at all depths. Biotic variation on the shelf was best defined by variation in bottom water primary production while sediment characteristics and bottom water oxygen, temperature and nutrients defined biotic variation at greater depth. Community structure differed significantly (p<0.01) among the three water masses (shelf-flowing South Australian current, upper slope Flinders current and lower slope Antarctic Intermediate Water) (H1). Although community differences between the du Couedic and Bonney regions were marginally above significance at p = 0.05 (H2), over half of the species captured were unique to each region. This supports the evidence from fish and megafaunal distributions that the du Couedic and Bonney areas are in different bioregions. Overall, the canyon interiors were not significantly different in community composition from the exterior (H3). However, both canyons had higher abundance and/or biomass, increased species dominance, different species composition and coarser sediments near the canyon heads compared to outside the canyons at the same depth (500 m), suggestive of heightened currents within the canyons that influence community composition there. At 1000-1500 m, the canyon interiors were depauperate, typical of V-shaped canyons elsewhere. The large number of species captured, given the relatively low sampling effort and focus on the larger macrofauna, support previous studies that identify the South Australian coast as a high biodiversity area.

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Constrained ordination of community composition by canonical analysis of principal coordinates (CAP) with a vector overlay of species having a Spearman rank correlation >0.6.Station codes are as in Fig 2. Species codes are listed in Table 5.
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pone.0143921.g008: Constrained ordination of community composition by canonical analysis of principal coordinates (CAP) with a vector overlay of species having a Spearman rank correlation >0.6.Station codes are as in Fig 2. Species codes are listed in Table 5.

Mentions: Canonical analysis of principal coordinates (CAP) showed the strong correlation of community composition with depth (H1) (δ12 = 0.97 and δ22 = 0.96), with the first axis separating the 100, 200, 1000 and 1500 m samples and the second axis separating the 100, 500 and 1500 m samples (Fig 8). Species most correlated with these axes (Spearman rank correlation >0.6) were the sponge Phycopsis sp., two bryozoans (Cornuticella sp. and an un-named species), five arthropods (the galatheid Phylladiorhynchus pusillus, the nebalian Paranebalia sp. and the amphipods Leucothoe sp., Gammaropsis sp. and Ampelisca sp.) and nine annelids (Odontosyllis corruscans, Syllinae sp. 1, Amaeana sp., Hesionidae sp., Glycera sp. 1, Pareurythoe chilensis, Sabellidae sp. 1, Leptoecia sp. and Prionospio sp. 1) (Table 5). The aplacophoran mollusc Chaetoderma sp. occurred only at 500 m. Many of these species were predators or suspension feeders.


Macrofaunal Patterns in and around du Couedic and Bonney Submarine Canyons, South Australia.

Conlan KE, Currie DR, Dittmann S, Sorokin SJ, Hendrycks E - PLoS ONE (2015)

Constrained ordination of community composition by canonical analysis of principal coordinates (CAP) with a vector overlay of species having a Spearman rank correlation >0.6.Station codes are as in Fig 2. Species codes are listed in Table 5.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664417&req=5

pone.0143921.g008: Constrained ordination of community composition by canonical analysis of principal coordinates (CAP) with a vector overlay of species having a Spearman rank correlation >0.6.Station codes are as in Fig 2. Species codes are listed in Table 5.
Mentions: Canonical analysis of principal coordinates (CAP) showed the strong correlation of community composition with depth (H1) (δ12 = 0.97 and δ22 = 0.96), with the first axis separating the 100, 200, 1000 and 1500 m samples and the second axis separating the 100, 500 and 1500 m samples (Fig 8). Species most correlated with these axes (Spearman rank correlation >0.6) were the sponge Phycopsis sp., two bryozoans (Cornuticella sp. and an un-named species), five arthropods (the galatheid Phylladiorhynchus pusillus, the nebalian Paranebalia sp. and the amphipods Leucothoe sp., Gammaropsis sp. and Ampelisca sp.) and nine annelids (Odontosyllis corruscans, Syllinae sp. 1, Amaeana sp., Hesionidae sp., Glycera sp. 1, Pareurythoe chilensis, Sabellidae sp. 1, Leptoecia sp. and Prionospio sp. 1) (Table 5). The aplacophoran mollusc Chaetoderma sp. occurred only at 500 m. Many of these species were predators or suspension feeders.

Bottom Line: Overall, the canyon interiors were not significantly different in community composition from the exterior (H3).However, both canyons had higher abundance and/or biomass, increased species dominance, different species composition and coarser sediments near the canyon heads compared to outside the canyons at the same depth (500 m), suggestive of heightened currents within the canyons that influence community composition there.The large number of species captured, given the relatively low sampling effort and focus on the larger macrofauna, support previous studies that identify the South Australian coast as a high biodiversity area.

View Article: PubMed Central - PubMed

Affiliation: Canadian Museum of Nature, Ottawa, Ontario, Canada.

ABSTRACT
Two South Australian canyons, one shelf-incising (du Couedic) and one slope-limited (Bonney) were compared for macrofaunal patterns on the shelf and slope that spanned three water masses. It was hypothesized that community structure would (H1) significantly differ by water mass, (H2) show significant regional differences and (H3) differ significantly between interior and exterior of each canyon. Five hundred and thirty-one species of macrofauna ≥ 1 mm were captured at 27 stations situated in depth stratified transects inside and outside the canyons from 100 to 1500 m depth. The macrofauna showed a positive relationship to depth in abundance, biomass, species richness and community composition while taxonomic distinctness and evenness remained high at all depths. Biotic variation on the shelf was best defined by variation in bottom water primary production while sediment characteristics and bottom water oxygen, temperature and nutrients defined biotic variation at greater depth. Community structure differed significantly (p<0.01) among the three water masses (shelf-flowing South Australian current, upper slope Flinders current and lower slope Antarctic Intermediate Water) (H1). Although community differences between the du Couedic and Bonney regions were marginally above significance at p = 0.05 (H2), over half of the species captured were unique to each region. This supports the evidence from fish and megafaunal distributions that the du Couedic and Bonney areas are in different bioregions. Overall, the canyon interiors were not significantly different in community composition from the exterior (H3). However, both canyons had higher abundance and/or biomass, increased species dominance, different species composition and coarser sediments near the canyon heads compared to outside the canyons at the same depth (500 m), suggestive of heightened currents within the canyons that influence community composition there. At 1000-1500 m, the canyon interiors were depauperate, typical of V-shaped canyons elsewhere. The large number of species captured, given the relatively low sampling effort and focus on the larger macrofauna, support previous studies that identify the South Australian coast as a high biodiversity area.

Show MeSH
Related in: MedlinePlus