Invertebrate micronekton and macrozooplankton in the Marguerite Bay region of the Western Antarctic Peninsula

Assemblages of micronektonic fishes and invertebrates in a gradient of regional warming along the Western Antarctic Peninsula

“…Vertical depth ranges for most dominant species encompassed the entire sampled water column, but neither E. crystallorophias nor P. antarctica were captured at depths greater than 500 m. This may be an artifact of the trawling effort since the few deep trawls (surface to 1000 m) were conducted at sites (Croker Passage and Palmer) where both species were either absent or present at very low densities. However, a study in the Marguerite Bay region during 2001/2002 yielded similar results (Donnelly and Torres, 2008;Parker et al, 2011), suggesting that the coastal distributions of both species may preclude their presence below 500 m at most of the present study sites. Deeper distributions of P. antarctica were recorded at Croker Passage in 1983 (Lancraft et al, 2004), but since only one fish was captured at that site in the present study (as well as being captured in a net that fished obliquely from the surface to depth) a valid comparison cannot be made.…”

“…Those species have previously been characterized as dominant taxa in various regions along the WAP including Bransfield Strait (Brinton and Townsend, 1991;Nordhausen, 1992;Piatkowski, 1985;Witek et al, 1985), Croker Passage (Lancraft et al, 2004), Gerlache Strait (Nordhausen, 1994a,b), the region extending from Anvers to Adelaide Island (Ross et al, 2008), and Marguerite Bay (Parker et al, 2011). Fishes constituted more than one-third of the taxa captured, but contributions to overall abundance were negligible, totaling less than 1% of the numbers captured.…”

“…The extent of mixing between the two assemblages as well as changes in the relative abundances of dominant species among sites were directly related to the unique bathymetry and hydrographic conditions present on the WAP shelf. Faunal mixing is maximized as CDW moves onto the shelf and mixes with cooler, fresher shelf waters (Donnelly and Torres, 2008;Parker et al, 2011). This was illustrated by the balance of oceanic and neritic fauna in assemblages at sites in the Marguerite Bay region and near Charcot Island.…”

Phylogeny and taxonomy of the enigmatic genusPetalidium(Decapoda, Sergestidae), with biological remarks

“…Parker et al . () found that the biomass of Petalidium ranges from 1–52 10 −4 mg m −3 during autumn to 58–156 10 −4 mg m −3 during winter.…”

“…The absolute abundance of Petalidium in the water column is exemplified by P. foliaceum in the Southern Ocean at 0.01–0.02 individuals m −2 (Walters, ). The same species showed abundances of 0.2–0.8 individuals 10000 m −3 during autumn and 0.7–2.4 individuals 10000 m −3 during winter (Parker, Donnelly & Torres, ). The available data for P. suspiriusum are similar, with approximately 1.0 individuals 10000 m −3 recorded by Kikuchi & Omori, ().…”