ISSN:
1573-8590
Keywords:
Chironanidae
;
diatoms
;
palaeoclimate
;
palaeolimnology
;
palaeoecology
;
palaeosalinity
;
salinity
;
postglacial
;
climate change
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geography
Notes:
Abstract Salinity fluctuations in lakes of semi-arid regions have long beenrecognised as indicators of palaeoclimatic change, and have provided avaluable line of evidence in palaeoclimatic reconstruction. In the presentstudy, fossil remains of diatoms and midges were used to reconstructsalinity changes at Mahoney Lake from the early postglacial, through theearly, mid and late Holocene. A transition from midges typical of afreshwater community (Protanypus, Sergentia, Heterotrissocladius,Cladopelma, Dicrotendipes) during the early postglacial, to those indicativeof saline environments (Cricotopus/Orthocladius, Tanypus) occurred in theearly Holocene. The midge-inferred salinity values reflected the shift fromfreshwater (0.031 g/L) immediately after deglaciation, to saline water (2.4to 55.2 g/L) in subsequent periods. A less saline period was found to haveoccurred after 1000 yr BP, suggesting a cooler or wetter period. The diatomrecord indicates similar trends, with freshwater taxa (e.g., Cyclotellabodanica var. aff. lemanica) dominating near the bottom of the core.Diatom-inferred salinities indicate that saline conditions (about 30 g/L)prevailed throughout subsequent Holocene time, although relatively freshconditions are indicated following deposition of the Mazama Ash, and fromabout 1500 yr BP until the present day. Midge and diatom-inferred salinityreconstructions for Mahoney Lake compare favorably with each other, and withclimate trends inferred from earlier palynological evidence. Thepalaeosalinity record thus contributes new data relevant to past climaticconditions, in a region where little data have previously been collected.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1009056003978
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