Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - The sensitivity of a Tanzanian crater lake to catastrophic tephra input and four millennia of climate change
AU - Barker, P.
AU - Telford, R.
AU - Merdaci, O.
AU - Williamson, D.
AU - Taieb, M.
AU - Vincens, A.
AU - Gibert, E.
N1 - May The sensitivity of a Tanzanian crater lake to catastrophic tephra input and four millennia of climate change Times Cited: 40
PY - 2000/4
Y1 - 2000/4
N2 - Diatom genera in many large East African lakes change little throughout the Holocene period suggesting relatively stable ecological conditions and some resilience to environmental change. Ecosystem stability is less common in smaller, more sensitive lakes, such as those within volcanic craters, where external impacts can cause abrupt and rapid fluctuations. A 4100-year diatom and cyanobacteria pigment record from Lake Massoko, a volcanic crater lake in southern Tanzania, is used to illustrate important switches in resource ratios following tephra deposition 1190 years ago. It is hypothesized that the tephra reduced the rate of P diffusion from the sediments and increased the Si:P ratio in the lake. A period of acute change in planktonic diatom communities resulted from the tephra impact and lasted c. 110 years. The magnitude of the change shown by the diatoms and their slow recovery from the tephra may be due in part to a coincident fall in lake level caused by a reduction in regional rainfall. The statistical significance of the tephra impact relative to that of catchment and climate change has been tested using variance partitioning and rate-of-change analysis. Multiproxy indicators show an important period of positive water balance 1700 ago and a relatively dry episode persisting between 1000 and 400 years ago. The lake ecosystem is shown to be highly sensitive to both climate change and tephra deposition.
AB - Diatom genera in many large East African lakes change little throughout the Holocene period suggesting relatively stable ecological conditions and some resilience to environmental change. Ecosystem stability is less common in smaller, more sensitive lakes, such as those within volcanic craters, where external impacts can cause abrupt and rapid fluctuations. A 4100-year diatom and cyanobacteria pigment record from Lake Massoko, a volcanic crater lake in southern Tanzania, is used to illustrate important switches in resource ratios following tephra deposition 1190 years ago. It is hypothesized that the tephra reduced the rate of P diffusion from the sediments and increased the Si:P ratio in the lake. A period of acute change in planktonic diatom communities resulted from the tephra impact and lasted c. 110 years. The magnitude of the change shown by the diatoms and their slow recovery from the tephra may be due in part to a coincident fall in lake level caused by a reduction in regional rainfall. The statistical significance of the tephra impact relative to that of catchment and climate change has been tested using variance partitioning and rate-of-change analysis. Multiproxy indicators show an important period of positive water balance 1700 ago and a relatively dry episode persisting between 1000 and 400 years ago. The lake ecosystem is shown to be highly sensitive to both climate change and tephra deposition.
KW - Diatoms
KW - tephra
KW - nutrient resources
KW - cyanobacteria pigments
KW - crater lakes
KW - East Africa
KW - Holocene
U2 - 10.1191/095968300672848582
DO - 10.1191/095968300672848582
M3 - Journal article
VL - 10
SP - 303
EP - 310
JO - Holocene
JF - Holocene
SN - 0959-6836
IS - 3
ER -