Four Antarctic marine mollusc shells, which were collected alive between 1917 and 1940, were analyzed by accelerator mass spectrometry to provide the first pre‐bomb radiocarbon measurements of biogenic carbonates from the Southern Ocean. After correcting for the impact of fossil fuel combustion (Suess Effect), radiocarbon activities of the pre‐bomb shells averaged −149.8±10.4‰. In contrast, the Δ 14C values for post‐bomb molluscs, echinoderms, brachiopods and foraminifera averaged −96.1±25.2‰. These biogenic carbonate Δ 14C values are nearly identical to pre‐bomb estimates (‐148‰ to −152‰) and post‐bomb measurements (−98.4±22.0‰) of the surface waters in the Southern Ocean. Average radiocarbon ages of the biogenic carbonates before and after 1950 (1303±84 years and 811±205 years, respectively), along with those from seals and penguins, indicate that the Antarctic marine radiocarbon reservoir has decreased in age by nearly 500 years during the second half of the 20th century. Marine species and seawater measurements firmly place the radiocarbon reservoir correction at 1300±100 years for calcareous marine fossils which are widespread, abundant and well‐preserved organic materials for interpreting ice‐sheet, climate and sea level impacts on the Antarctic marine ecosystem during the Holocene.

This overview examines available circum-Antarctic glacial history archives on land, related to developments after the Last Glacial Maximum (LGM). It considers the glacial-stratigraphic and morphologic records and also biostratigraphical information from moss banks, lake sediments and penguin rookeries, with some reference to relevant glacial marine records.

New data on marine sediments, seawater paleotemperatures, and the occupation history of Adélie penguins indicate that modern ice-free conditions in the southern Ross Sea developed only within the last 1000 yr. Here we show that penguins permanently abandoned the southern Victoria Land Coast 2000 yr ago when extensive sea-ice cover blocked access to ice-free terrain for breeding. The first colonization of Ross Island in East McMurdo Sound, where over 300 000 penguins breed today, did not commence until after 1170 yr BP when coastal areas became exposed from under the Ross Ice Shelf. Our results demonstrate that investigations of abandoned penguin colonies can provide increased resolution to Holocene paleoclimatic records and paleoceanographic conditions in Antarctica.

This review assesses the circumpolar occurrence of emerged marine macrofossils and sediments from Antarctic coastal areas in relation to Late Quaternary climate changes. Radiocarbon ages of the macrofossils, which are interpreted in view of the complexities of the Antarctic marine radiocarbon reservoir and resolution of this dating technique, show a bimodal distribution. The data indicate that marine species inhabited coastal environments from at least 35 000 to 20 000 yr BP, during Marine Isotope Stage 3 when extensive iceberg calving created a 'meltwater lid' over the Southern Ocean. The general absence of these marine species from 20 000 to 8500 yr BP coincides with the subsequent advance of the Antarctic ice sheets during the Last Glacial Maximum. Synchronous re-appearance of the Antarctic marine fossils in emerged beaches around the continent, all ofwhich have Holocene marine-limit elevations an order of magnitude lower than those in the Arctic, reflect minimal isostatic rebound as relative sea-level rise decelerated. Antarctic coastal marine habitat changes around the continent also coincided with increasing sea-ice extent and outlet glacial advances during the mid-Holocene. In view ofthe diverse environmental changes that occurred around the Earth during this period, it is suggested that Antarctic coastal areas were responding to a mid-Holocene climatic shift associated with the hydrological cycle. This synthesis of Late Quaternary emerged marine deposits demonstrates the application of evaluating circum-Antarctic phenomena from the glacial-terrestrialmarine transition zone.

Geographic information system (GIS) analysis with bathymetric, substrate, and side scan sonar (SSS) data was used to assess both spatial and temporal expansion of exotic dreissenid mussels onto sedimentary habitats in Lake Erie. These data were used for developing multiple regression models with substrate types and SSS data to interpret the expansion of Dreissena assemblages across the central and western basins of Lake Erie from 1994 to 1998. The 1994-1996 GIS model predicted the 1997 SSS measurements of Dreissena coverage correctly in 84% of the cases (n ϭ 50). Similarly, the 1994-1997 GIS model predicted the 1998 SSS measurements of Dreissena coverage correctly in 80% of the cases (n ϭ 20). These models indicated that Dreissena coverage ranged from Ͻ1% on muds in 1994 to 67% on sands and gravels in 1997. Based on all of the substrates, the 1994-1997 model indicates that Dreissena beds have been expanding since 1994 at 1,000 Ϯ 6 km 2 yr Ϫ1 and presently occupy 5,484 Ϯ 32 km 2 of the 25,734 km 2 sedimentary bottom of Lake Erie. Our observations indicate that expanding Dreissena beds are altering soft-substrate habitats and influencing the ecosystem dynamics throughout Lake Erie. Furthermore, this study demonstrates that the distribution, abundance, and ecosystem impacts of invasive species in other watersheds can be accurately described and interpreted over diverse spatial and temporal scales using GIS models.