B. Sommer et P. Horwitz, Water quality and macroinvertebrate response to acidification following intensified summer droughts in a Western Australian wetland, MAR FRESH R, 52(7), 2001, pp. 1015-1021
A decline in pH from similar to6-8 to similar to4-5 over a period of 4 year
s was detected during routine monitoring of surface waters at Lake Jandabup
. This was accompanied by lower water levels, shorter periods of inundation
and measurable changes in other attributes of the water: sulfate, iron and
ammonium concentrations increased markedly, and filterable reactive phosph
orus and colour (gilvin) decreased. Macroinvertebrate family richness did n
ot change notably over this period, but there were shifts in community stru
cture: ostracods, isopods and oligochaete worms became less abundant; amphi
pods, mayflies and gastropods disappeared, while ceratopogonids (Diptera) a
nd macrothricid cladocerans increased in abundance. Historical evidence sug
gests that at least one other acidification event has occurred in the recen
t past. Mechanisms associated with the acidification, and the wetland's cap
acity to recover from such events, are discussed.