Harry R. Burton

Origins and Biological Accumulation of Small Plastic Particles in Fur Seals from Macquarie Island

Abstract One hundred and sixty four plastic particles (mean length 4.1 mm) recovered from the scats of fur seals (Arctocephalus spp.) on Macquarie Island were examined. Electron micrographs of 41 of the plastic particles showed that none could be identified as plastic pellet feedstock from their shapes. Commonly, such pellets are cylindrical and spherical. Instead, all the 164 plastic particles from the seal scats were angular particles of 7 colors (feedstock particles are normally opaque or white) and could be classified into 2 categories: i) fragmented along crystal lines and likely to be the result of UV breakdown; and ii) worn by abrasion (where striations were clearly visible) into irregular shapes with rounded corners. White, brown, green, yellow and blue were the most common colors. In composition, they came from 5 polymer groups; poly-ethylene 93%, polypropylene 4%, poly(1-Cl-1-butenylene) polychloroprene 2%, melamine-urea (phenol) (formaldehyde) resin 0.5%, and cellulose (rope fiber) 0.5%. The larger groups are buoyant with a specific gravity less than that of seawater. These small plastic particles are formed from the breakdown of larger particles (fragments). Their origin seems to be from the breakdown of user plastics washed ashore and ground down on cobbled beaches. Certainly most particles (70%) had attained their final form by active abrasion. It is hypothesized that the plastic particles were washed out to sea and then selected by size and consumed by individuals of a pelagic fish species, Electrona subaspera, who in turn were consumed by the fur seals. Thus, the particles were accumulated both by the fish and the seals in the usual process of their feeding.

Dimethylsulfide and the algaPhaeocystis pouchetii in antarctic coastal waters

The concentrations of dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) were measured in water collected from the Southern Ocean 10 km offshore from Davis Station, Antarctica, during the period May 1987 to January 1988, inclusive. During winter and spring, when the sea-ice was up to 1.9 m thick, DMS, DMSP and DMSO concentrations were low (0.2 to 1.5 nM), as were phytoplankton numbers. The maximum concentration of the sulfur compounds generally occurred in the top 10 m of the water column. DMS levels rose dramatically from early December onwards, reaching a peak of 290 nM at a depth of 15 m in January. This concentration is higher than reported elsewhere in the ocean. These high concentrations occurred at the same time as a bloom of the algaPhaeocystis pouchetii. A significant correlation occurred between DMS concentration and cell numbers of the alga. The ratio of DMS concentration to the number of cells of the alga was considerably higher than reported for blooms of this species elsewhere in the ocean. Up to 10% of the total global flux of DMS to the atmosphere may emanate from antarctic seas.

Weaning mass and the future survival of juvenile southern elephant seals, Mirounga leonina , at Macquarie Island

Seals that survived their first year were on average 2% and 4% heavier at birth and at weaning than the “non-survivors”. First year survival rates calculated for weaners over 135 kg weaning masses showed these weaners had higher survival rates than those less than 95 kg at weaning (71.55% and 54.15% respectively). Heavy weaners had greater fat reserves than light weaners and gained relatively more mass during lactation. Size, and therefore condition at weaning, influences first year survival.

Halobacterium lacusprofundi sp. nov., a Halophilic Bacterium Isolated from Deep Lake, Antarctica

Summary Halobacterium lacusprofundi sp. nov. is described based on the characteristics of two strains (ACAM 32, ACAM 34) of red halophilic bacteria isolated from Deep Lake, a hypersaline, Antarctic lake. Bacteria which could grow on media prepared with undiluted Deep Lake water have not been isolated previously from Deep Lake. Cells were pleomorphic rods which lysed when suspended in distilled water. Unlike other halobacteria, the strains grew at 4°C, albeit very slowly. Fastest generation times (11 h) occurred between 31–37°C. The strains were not proteolytic, did not produce acids from sugars, but utilized a wide range of carbon sources including sugars, alcohols, and organic acids for growth. The strains grew in media with Mg ++ concentrations ranging from 0.005 to 1.0 mol/l and with NaCl concentrations ranging from 1.5 mol/l to saturation. Cells contained isoprenoid neutral lipids typical of halophilic archaebacteria. The major constituents were diphytanyl glyceryl ether, squalene and dihydrophytol. Approximately 30% of the total ether lipids consisted of at least four glyceryl ethers containing one or more double bonds in the phytenyl group. Also present were squalane, dihydrosqualene, tetrahydrosqualene, dihydrophytol and phytol. The G+C content of the major component DNA was 65 to 66 mol%. Satellite band DNA was present with G+C contents ranging from 54 to 57 mol%. Analysis of the 16S rRNA catalogue showed strain ACAM 34 was most closely related to Halobacterium saccharovorum ATCC 29252 (S AB value 0.74) but only distantly related to Haloferax volcanii ATCC 29605 (S AB value 0.43), Haloarcula vallismortis ATCC 29715 (S AB value 0.36), Halococcus morrhuae ATCC 17082 (S AB value 0.39) or Natronococcus occultus NCMB 2192 (S AB value 0.47). The type strain is UQM 3107 (ACAM 34).

Bacterial and algal hydrocarbons in sediments from a saline Antarctic lake, Ace Lake

Capillary gas chromatography-mass spectrometry (C-GC-MS) and Iatroscan thin layer chromatography-flame ionisation detection (TLC-FID) were used to study hydrocarbon distributions in a sediment core from Ace Lake, a saline, meromictic lake in the Vestfold Hills of Antarctica. Hydrocarbons were abundant in most core sections (up to 125/μg/g dry wt), particularly in near-surface samples, and the distributions were very complex. Major constituents were identified as phytane, 2,6,10,15,19-pentamethyleicosane, tetrahydrosqualene, a mixture of phytenes, cholesta-3,5-diene and fern-7-ene. Smaller amounts of sterenes and hopenes were also present. The predominance of the first 3 acyclic isoprenoids in sediments buried less than 30 cm is consistent with high populations of methanogenic bacteria known to be present. Phytenes were abundant in all core sections, and there was no relationship between their abundance and that of phytane which suggests that they were not derived from methanogenic bacteria. Phytadienes were minor constituents at all depths studied. An unusual feature of some distributions was the high concentrations of fern-7-ene which was the major hydrocarbon in the 20–25 cm core section. This alkene was only abundant in sediments which contained high concentrations of methanogen markers suggesting that it may also be indicative of anoxic depositional environments. A possible source might be from purple non-sulphur bacteria. High concentrations of straight-chain C29 and C34 alkenes were also found in these sediments but their origin has not been determined. Major changes in the hydrocarbon distributions with depth indicate that the depositional environment in the lake has altered dramatically since the lake was formed less than 8000 years ago. The present condition of permanent anoxic bottom waters probably developed only in the last 1000 years.

Climate change and seal survival: evidence for environmentally mediated changes in elephant seal, Mirounga leonina, pup survival

Maternal and physical factors play a significant role in animal life-history variability, which means that large scale climate change has the potential to affect the size and dynamics of animal populations indirectly through maternal investment and directly through conditions that animals are exposed to. However, little is known about the effects of large-scale oceanographic events such as the El-Niño southern oscillation (ENSO) that influence productivity in the Southern Ocean and the abundance, quality and distribution of prey. The possible mechanisms by which physical factors and primary productivity could influence life-history traits, such as survival of apex predators, includes direct influences such as food availability and foraging success and indirect influences such as stored maternal investment and resource transfer during lactation. Here, we quantify the relative contribution of maternal investment and climate conditions at remote foraging sites to survival in the first year of life for southern elephant seals. We present evidence linking climate (ENSO) and variations in a key demographic parameter—first-year survival—and demonstrate that survival was highest during ENSO events and that the ability of mothers to store and acquire resources, which is typically related to ocean productivity, is the most important determinant of survival in the first year. This functional link provides valuable insights that can be used to model the responses of the seal populations to climate change scenarios.

Spatial distribution of dimethylsulfide and dimethylsulfoniopropionate in the Australasian sector of the Southern Ocean

During 1991–1995, seven voyages were made to the Southern Ocean to determine the distribution of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) in seawater and air in the Australasian sector (60°E to 165°E). Measurements of DMSP in sea ice were also made. During the summer months the Subtropical Convergence (STC) and Antarctic Convergence (AC) were identified as important source regions of these sulfur compounds. In the Seasonal Ice zone (SIZ) there were marked longitudinal differences possibly reflecting higher productivity and the extent of the sea ice in this region. Levels of DMSP in sea ice cores were consistent with this regional difference. High and variable concentrations of DMSP also occurred in the Subantarctic Zone (SAZ) (45°-53°S), decreasing to lower levels around 64°S, close to the Antarctic Divergence (AD). Upwelling of deep water around the AD is suggested to have been responsible for the low biological activity and low DMSP levels. While there was generally a good relationship between DMSPp and biomass, there was a marked difference in the DMSPp:chlorophyll a ratio between regions, and between years. DMSP was generally negatively correlated with dissolved nitrate, however, it was unclear if the level of nitrate directly affected DMSP production. DMSw levels were highest in the mixed layer, with lower, yet detectable, levels in the deeper ocean. DMSw was occasionally elevated in Antarctic Bottom Water (AABW), suggesting that ice shelf water transports this substance to deeper waters. DMSP was not found above detection limits below the mixed layer, but some evidence was found that DMSP may be transported to deeper waters, close to the Antarctic continent.

Sedimentological and stable-isotope evolution of lakes in the Vestfold Hills, Antarctica

The sedimentological, chemical and isotopic characteristics of sediment cores from three slightly saline to hypersaline lakes (Highway, Ace and Organic Lakes) and two marine inlets (Ellis Fjord and Taynaya Bay) in the Vestfold Hills, Antarctica, have been examined. Sections of the cores deposited in marine environments are characterized by uniform, regularly laminated, fine-grained, organic-rich sediments, with uniform organic δ13C values (−18.0 to −19.4% vs. PDB) and sulfur contents. In contrast, sediments deposited in lacustrine environments are extremely heterogeneous, varying from finely laminated mat-like sequences to poorly sorted clastic-rich sediments. Authigenic monohydrocalcite and aragonite occur in some lake sediments. The δ13C values of organic matter in the lacustrine sediments exhibit an extremely wide range (−10.5 to −25.3‰) that can be related to variations in physico-chemical conditions in the lake waters. Strongly negative organic-δ13C values coupled with high sulfur contents are indicative of an anoxic zone in the overlying lake waters, whereas less negative organic-δ13C values coupled with low sulfur contents are indicative of well-mixed oxic conditions. Particularly high organic-δ13C values result during high levels of microbial activity in the lakes, due to high rates of photosynthetic CO2 fixation. The large shifts in organic-δ13C are not necessarily accompanied by any change in macroscopic sedimentological characteristics, illustrating the utility of isotopic investigations in these environments. The δ13C composition of authigenic carbonate in hypersaline Organic Lake sediments provides a record of changes in palaeoproductivity, while the δ18O of the carbonate provides information on rates of meltwater input and evaporation in the lake. 14C-dating suggests that Highway Lake was isolated from the sea by isostatic uplift at least 4600 yr before present (B.P.) whereas Organic Lake was isolated at approximately 2700 yr B.P. Apparent emergence rates calculated from the 14C ages range from 1.0 to 2.1 mm yr−1. The ‘reservoir effect’ in the lacustrine and marine environments is variable, but probably does not exceed ∼ 1000 yr in any of the lakes examined.

Foraging Areas of Southern Elephant Seals, Mirounga leonina, as Inferred from Water Temperature Data

Fourteen time-depth-temperature recorders were recovered from adult southern elephant seals (Mirounga leonina) returning to Macquarie Island to breed or moult. The resulting temperature/depth profiles indicated that all four males spent most of their time in waters lying over the Antarctic Continental Shelf, whereas only one of the ten females spent any time there. Five of the females foraged just off the Antarctic Continental Shelf. and the other five remained near the Antarctic Polar Front.

Field immobilisation of southern elephant seals with intravenous tiletamine and zolazepam.

Southern elephant seals (Miroungo leonina) were immobilised with a mixture of tiletamine and zolazepam administered intravenously at a mean (sd) dose rate of 0.46 (0.08) mg/kg. This dose provided a satisfactory degree of anaesthesia with no side effects, and the induction, duration and recovery times were short. The mean (sd) induction time was 26 (9) seconds and the mean level of anaesthesia was 4.4 units on an eight-point scale. Male seals were given less drug than female seals, remained immobilised for shorter periods and recovered sooner. The mean (sd) dose of drug administered to males was 0.44 (0.06) mg/kg and to females 0.48 (0.08) mg/kg, and the mean (sd) duration times were 14.9 (4.5) minutes and 16.1 (5.3) minutes. The mean (sd) time taken to recover from immobilisation was 14.5 (4.6) minutes for males and 15.7 (5.3) minutes for females. Physiological condition and size significantly affected the duration of anaesthesia. Thin seals remained immobilised for 18 (7) minutes whereas fatter seals remained immobilised for 15 (4) minutes (P<0.0001).