Small-scale spatial variation of soft-bottom polychaete biomass in an Antarctic glacial fjord (Ezcurra Inlet, South Shetlands): comparison of sites at different levels of disturbance

Abstract

There is still only a small number of studies dedicated to Southern Ocean benthic biomass, especially on species level. Here, we analyze polychaete biomass in two areas of the Antarctic fjord Ezcurra Inlet characterized by different levels of disturbance associated with activity of glaciers. Material was collected in March 2007 in the 90-130 m depth range. Twenty van Veen grab (0.1 m 2 ) samples were collected in the inner area of the fjord and 20 in the fjord mouth. Cluster analysis clearly separated those two parts of the fjord. Mean total biomass was significantly higher in the outer region (14.4 ± 5.5 g/0.1 m 2 ) compared with the inner part (3.6 ± 0.8 g/0.1 m 2 ). The highest biomass in the outer, not disturbed area was noted for Amphitrite kerguelensis, Aphelochaeta/Chaetozone, Scalibregma inflatum, Euchone pallida and Maldane sarsi antarctica, while in the inner region, only Aphelochaeta/ Chaetozone had high biomass values. Average individual biomass and biomass of majority of polychaete functional groups was also higher in the outer area. Comparison of species composition and abundance with data collected 30 years ago in the studied area revealed also important differences in community structure.

Can benthic foraminifera serve as proxies for changes in benthic macrofaunal community structure? Implications for the definition of reference conditions

“…Amphiura filiformis has been reported to be sensitive to severe disturbances around oil platforms (Olsgard & Gray 1995). Note that the tolerance level of S. inflatum is rather uncertain since it has been reported to be either sensitive (Mirza & Gray 1981, Rygg 1985b, Nilsson & Rosenberg 1994, Rosenberg et al 2001, Pabis & Sobczyk 2015 or tolerant (Rygg 1985a, Aschan & Skullerud 1990, Borja et al 2000, Levin et al 2009 to disturbances.…”

Low abundance and high species richness: the structure of the soft-bottom isopod fauna of a West Antarctic glacial fjord

“…Some long-term changes in the structure of benthic communities have already been observed in the Antarctic (e.g. Pabis and Sobczyk 2015;Moon et al 2015;Sahade et al 2015), but there remains a need to develop a system of monitoring sites that will allow comprehensive and meaningful evaluation of global environmental changes in the benthic fauna of the whole region.…”

Eulalia picta Kinberg, 1866 – tube builder or specialized predator?

“…Both of those species are also common and abundant in the Admiralty Bay. They dominated at sites that were sampled in our study but were much less abundant in the disturbed inner region of the fjord (Siciński 2004;Pabis and Sobczyk 2015). If that was the origin of the E. picta tubes it might prove that this species is highly specialized predator feeding on sessile maldanids or oweniids and uses their tubes as the refugium.…”

“…Nevertheless, it can be also associated with sediment fractions preferred for tube building. Generally, the polychaete community in the outer region of the Ezcurra Inlet is characterized by a much higher number of tube building species Pabis and Sobczyk 2015). General morphology and structure of the E. picta tubes resembles the tubes of the common Antarctic maldanid Rhodine intermedia Arwidsson, 1911 and the owenid Galathowenia scotiae (Hartman 1966).…”