Ice disturbance is possibly the major structuring element of polar nearshore biological cornrnunities. Effects range from encapsulation by ice forming on rock substrata to gouging and trampling by bergs. Some 15 to 20% of the world's oceans are affected by this phenomenon, yet measurements of the extent of biological destruction from iceberg irnpacts and subsequent community recovery are very rare. Comrnunities can be held at early successional Stages. or even completely destroyed by scouring. and these effects occur from the intertidal to depths around 500 m in Antarctica. The wide scales of disturbance intensity are thought to add to the overail high levels of Antarctic benthic biological diversity. which has recently been shown to be similar to tropical areas. Data here indicate >99.5 % removal of all macrofauna and >90% removal of most meiofauna by iceberg impact on a soft-sediment habitat at Signy Island. Antarctica. Species return was via locomotion. advection or larval recolonisation, and al13 mechanisms worked on different timescales. Locomotion caused groups to return ~rithin 10 d of a n impact. Storms with wind speeds around 100 km h-' induced water movements intense enough to advect meiofauna to the 9 m depth site. However, it was only dunng the strongest storm which occurred during the study (maximum wind speed 148 km h-I) that water movements were powerful enough to redistribute small macrofauna such as the bivalve Mysella charcoti.

In 2009, the European Commission estimated that 88 % of monitored marine fi sh stocks were overfi shed, on the basis of data that go back 20 to 40 years and depending on the species investigated. However, commercial sea fi shing goes back centuries, calling into question the validity of management conclusions drawn from recent data. We compiled statistics of annual demersal fi sh landings from bottom trawl catches landing in England and Wales dating back to 1889, using previously neglected UK Government data. We then corrected the fi gures for increases in fi shing power over time and a recent shift in the proportion of fi sh landed abroad to estimate the change in landings per unit of fi shing power (LPUP), a measure of the commercial productivity of fi sheries. LPUP reduced by 94 % -17-fold -over the past 118 years. This implies an extraordinary decline in the availability of bottom-living fi sh and a profound reorganization of seabed ecosystems since the nineteenth century industrialization of fi shing.

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The waters surrounding Antarctica are amongst the most isolated large areas of continental shelf, cut off for about 15 to 30 million yr by both deep water and the oceanographic barrier of the Polar Frontal Zone (PFZ). Although certain taxa are notably absent, shelf seabed richness (of the mostly endemic species) can be very high. Most of Antarctica's shallow shelf lies between 67 and 72°S, although virtually all the growing southern polar marine biology literature has been carried out to the north or south of this. Here we report one of the first, and the most detailed, quantitative studies of benthic faunal abundance, diversity and biomass from within this latitudinal belt (at Adelaide Island, Antarctic Peninsula). Representatives of 16 phyla, 25 classes, 34 orders and at least 75 species were found in the 40 samples of 0.25 m 2 area. This is rich, especially for polar localities described to date. Faunal abundance increased logarithmically from <100 to >10 000 individuals m -2 from the intertidal to 35 m respectively. Annelids and bryozoans were the most numerous, and cryptofauna (such as these 2 phyla) exerted a major influence on both patterns and absolute values of diversity. Subtidal biomass increased from 500 to 10 000 g m -2 at 3 to 35 m respectively and is, overall, the highest for any polar locality within the 0 to 40 m depth range. The echinoid Sterechinus neumayeri was the principal cause of these high values as it dominated biomass at all subtidal depths, although molluscs (particularly the limpet Nacella concinna) were important in the shallows. Striking subtidal zonation was apparent, demarked by both inter-and intra-specific characteristics. We suggest that faunistic bathymetric organisation essentially forms 3 zones comprising different suites of species and is also demarked by the population structure of the species S. neumayeri. Not only do the species S. neumayeri and N. concinna show strong zonation in occurrence but also their grazing activity is probably a strong agent producing similar patterns in cryptobenthos (through removal of recruits). We propose a general schematic (a diagram) of zonation as declining in the littoral southwards towards the PFZ and increasing in the subtidal southwards from the PFZ.

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