TY - JOUR
T1 - Recent benthic foraminifera from Twofold Bay, Eden NSW
T2 - Community structure, biotopes and distribution controls
AU - Dean, L. F.
AU - de Deckker, P.
PY - 2013/6
Y1 - 2013/6
N2 - Twofold Bay lies at the confluence of two oceanic boundaries, the near end of the East Australian Current and waters from the Southern Ocean. The Bay is NSW's largest commercial fishing port and has been home to much anthropogenic activity, ranging from whaling, mussel farming, timber export, large boat traffic, Australian Navy activities and recreational fishing. We investigated the sediments and associated foraminifer fauna in the bay and identified four different sedimentological associations linked to local currents and water depths and three foraminiferal associations, with live to dead specimen ratios established for each sample site. Three principal biotopes have been identified using cluster analysis of foraminiferal assemblages, with each biotope characterised by a specific faunal population and substrate type: (1) Inner Bay Biotope, characterised by Elphidium aff. advenum and predominantly very fine-fine sand substrates (63-250 μm); (2) Outer Bay Biotope characterised by Discorbis dimidiatus and medium-coarse sand substrates (250-1000 μm); (3) Harbour Biotope characterised by the widespread species Elphidium advenum macelliforme and bimodal sediments with very fine-coarse silts (2-63 μm) and medium sands (250-500 μm). Substrate type and energy intensity are proposed as limiting factors to foraminiferal distribution and composition. In addition, a short (21 cm long) core obtained from near the entrance of Eden Harbour has been examined in terms of foraminifer assemblages established for the bay. Microfaunal composition shifts clearly correlate with sediment colour changes, while foraminiferal and sedimentary data indicate strong concordant physical and ecological patterns. However, radiocarbon dates from various levels in the core point to sediment disturbance, contradicting this hypothesis. Hence, the dating of the sequence remains problematic.
AB - Twofold Bay lies at the confluence of two oceanic boundaries, the near end of the East Australian Current and waters from the Southern Ocean. The Bay is NSW's largest commercial fishing port and has been home to much anthropogenic activity, ranging from whaling, mussel farming, timber export, large boat traffic, Australian Navy activities and recreational fishing. We investigated the sediments and associated foraminifer fauna in the bay and identified four different sedimentological associations linked to local currents and water depths and three foraminiferal associations, with live to dead specimen ratios established for each sample site. Three principal biotopes have been identified using cluster analysis of foraminiferal assemblages, with each biotope characterised by a specific faunal population and substrate type: (1) Inner Bay Biotope, characterised by Elphidium aff. advenum and predominantly very fine-fine sand substrates (63-250 μm); (2) Outer Bay Biotope characterised by Discorbis dimidiatus and medium-coarse sand substrates (250-1000 μm); (3) Harbour Biotope characterised by the widespread species Elphidium advenum macelliforme and bimodal sediments with very fine-coarse silts (2-63 μm) and medium sands (250-500 μm). Substrate type and energy intensity are proposed as limiting factors to foraminiferal distribution and composition. In addition, a short (21 cm long) core obtained from near the entrance of Eden Harbour has been examined in terms of foraminifer assemblages established for the bay. Microfaunal composition shifts clearly correlate with sediment colour changes, while foraminiferal and sedimentary data indicate strong concordant physical and ecological patterns. However, radiocarbon dates from various levels in the core point to sediment disturbance, contradicting this hypothesis. Hence, the dating of the sequence remains problematic.
KW - Fisher Alpha index
KW - cluster analysis
KW - dissolution
KW - diversity
KW - foraminiferal biotope
KW - radiocarbon
KW - reworking
KW - sedimentary facies
UR - http://www.scopus.com/inward/record.url?scp=84881025453&partnerID=8YFLogxK
U2 - 10.1080/08120099.2013.792294
DO - 10.1080/08120099.2013.792294
M3 - Article
SN - 0812-0099
VL - 60
SP - 475
EP - 496
JO - Australian Journal of Earth Sciences
JF - Australian Journal of Earth Sciences
IS - 4
ER -