Biomass, production and microhabitat characteristics near the freeboard of ice floes in the Ross Sea, Antarctica, during the austral summer

Abstract

The physical, chemical and biological characteristics of surface and freeboard habitats in the summer pack ice in the eastern Ross Sea, Antarctica, were documented in a continuing effort to determine the factors controlling the distribution, production and succession of sea-ice biota. Three longitudinal transects from approximately 65³ to 74³ S in the western Ross Sea along135³,150³ and 165³ W were visited where samples of slush and slush interstitial water from surface and freeboard habitats as well as sea water were collected at every degree of latitude. Freeboard and surface habitats, found at all stations in the pack ice, contained a large range (five orders of magnitude) of microalgal biomass (measured as chlorophyll a concentrations) and nutrients ranging from below levels of detection to those of the surrounding sea water. The geophysical attributes of the freeboard habitat (i.e. a layer of semi-consolidated ice overlying a layer containing unconsolidated ice crystals and sea water) are consistent with previous descriptions of this environment. However, additional information is presented on the range of biomass concentrations as well as the small-scale distributions of the habitat and biota.

Strategies for the Simulation of Sea Ice Organic Chemistry: Arctic Tests and Development

“…Choices are typical for the Bering and Pacific Arctic entryway [58]. Detailed observations of cell densities within the pack were called upon for initialization [41,66]. Competitive exclusion dominates in our simulations, but the real situation is generally not so extreme.…”

“…Upper level ecosystems are mentioned for the Arctic almost solely anecdotally, for example in the monograph by Melnikov [64]. A working hypothesis is that freeboard and infiltration layers better studied in the Southern Hemisphere [42,66] occur only peripherally and occasionally in the Arctic -although this may be changing as northern ice becomes more seasonal.…”

“…It is anticipated that eventually, bottom layer pennate diatoms, smaller autotrophs inhabiting central ice and even specialists such as Phaeocystis will be numerically segregated [7,61,66,74,99,[111][112]. Hence the subscript i,auto denotes the ith autotroph and our notation can be introduced as…”

“…Nitrogen inorganics are interrelated by recycling processes. Oxidation states are linked to one another along the overall metabolism then by microbial chemistry [16,66], and routings are once again prominent in the NH4 + case. We model nitrification after reference [33] and all of respiration is presumed to flow through ammonia.…”

“…These may be thought of in turn as pennates, cryptophytes plus dino-and other microflagellates, and finally Phaeocystis. The suite is dominant in vertical sections from many sea ice sample cores [41,66,111]. All the classes are notable producers of organics [7,20,113,118].…”