The Xanthophyceae and Chlorophyceae of the Western Ross Sea, Victoria Land, Antarctica and Macquarie Island collected under the direction of Prof. Dr. J. S. Zaneveld (1963—1967)

During the austral summer seasons of 1963-1964 and 1964-1965, and during the austral winter season of 1967 Prof. Dr. J.S. Zaneveld made collection expeditions to the western Ross Sea. In 1965 collections were also made from the U.S.C.G. icebreaker ‘Glacier’, around the western Ross Sea and around the Balleny Islands. During the same cruise Macquarie Island was visited. Most collecting was carried out by means of scuba-diving. Prof. Zaneveld was accompanied on these expeditions by W.I. Simmonds (1963-1964), J.M. Curtis (1964-1965), J.K. Fletcher (1964- 1965), D.M. Bresnahan (1967), and L.L. Nero (1967), during these periods students at Old Dominion University, Norfolk, Virginia, U.S.A. In the harsh Antarctic environment the algae discussed in the present paper occur in aquatic habitats (freshwater, brackish water, and saline water) be it covered with ice or not, in melted snow and on icebergs. Identification and synonymy of the eleven taxa reported is based mainly on the Antarctic and sub-Antarctic literature. One of the algal taxa mentioned belongs to the Xanthophyceae and ten to the Chlorophyceae. Several of these taxa are newly recorded for the area or part of it under discussion. Some critical notes are made concerning the Antarctic Ulotrichales, as well as a short discussion on the correct name of the type species of the genus Klebsormidium. A new species of this genus is described. The species collected ar Heterococcus moniliformis Vischer, 1937; Chlamydomonas aft. ballenyana Kol in Kol & Flint, 1968, Stichococcus nivalis Chodat, 1917; Klebsormidium drouetii Wagner & Zaneveld, nov. spec.; Ulothrix implexa (Kützing) Kützing, 1849; Ulothrix australis Gain, 1911; Urospora penicilliformis (Roth) Areschoug, 1874; Monostroma hariotii Gain, 1911; Prasiola crispa (Lightfoot) Meneghini, 1837 var. antarctica (Küitzing) Knebel, 1935 forma antarctica (Kützing) Knebel, 1935; Chaetomorpha mawsonii Lucas, 1919; and Lola-irregularis Zaneveld, 1966. The remarkable vertical distribution of the chlorophyte Monostroma hariotii in the Ross Sea, Antarctica, i.e. from the lower eulittoral down to 348 meters indicates again that the factor ‘light’ is only one of the many features influencing the vertical distribution of marine algae

Trophic interactions within the Ross Sea continental shelf ecosystem

The continental shelf of the Ross Sea is one of the Antarctic's most intensively studied regions. We review the available data on the region's physical characteristics (currents and ice concentrations) and their spatial variations, as well as components of the neritic food web, including lower and middle levels (phytoplankton, zooplankton, krill, fishes), the upper trophic levels (seals, penguins, pelagic birds, whales) and benthic fauna. A hypothetical food web is presented. Biotic interactions, such as the role of Euphausia crystallorophias and Pleuragramma antarcticum as grazers of lower levels and food for higher trophic levels, are suggested as being critical. The neritic food web contrasts dramatically with others in the Antarctic that appear to be structured around the keystone species Euphausia superba. Similarly, we suggest that benthic–pelagic coupling is stronger in the Ross Sea than in most other Antarctic regions. We also highlight many of the unknowns within the food web, and discuss the impacts of a changing Ross Sea habitat on the ecosystem