13. The Temperate Rainforest Lakes of Chile and Canada
271
Araucanian lakes. More information on bacterioplankton and autotrophic
picoplankton densities in Chilean lakes is needed before meaningful
comparisons can be made. Nonetheless, it is of interest to note that
bacteria and autotrophic picoplankton (APP) show similar density ranges
in both lake systems although APP, as is expected, reach greater densities
in the more productive Chilean lakes (Table 13.1) .
Phytoplankton
The Chilean lakes are dominated by the diatoms Aulacoseira (formerly
Melosira) and Rhizosolenia and the chrysophyceaen Dinobryon spp.
during much of the year (Campos et aI. , 1988), with a predominant spring
peak in microphytoplankton biomass and production (Campos, 1984;
Campos et aI., 1988). Cyclotella, Rhizosolenia, Aulacoseira, and Fragilaria
are the most common diatoms in BC lakes, but their abundance is very
low compared to APP, and chrysophyte, and chryptomonad nanoflagellates (Stockner, 1987). Large spring peaks of microphytoplankton biomass
and/or production do not commonly occur in coastal lakes, but at fertilized
stations within lakes sometimes they do take place (Stockner & Costella,
1980, Stockner, 1987).
Zooplankton
Zooplankton communities of Chilean lakes are dominated by Boeckellid
calanoid copepods (Boeckella gracilipes, B. michaelseni , and B. meteoris).
Also present, but less common, are the small cladoceran Neobosmina
chilensis, some cyclopoid copepods and rotifers (Soto and Zuniga, 1991).
Large copepods or cladocerans are rare, notably daphnids that are
common in most lakes of the northern hemisphere. Most of the Boeckellids are herbivorous and regulate the abundance of certain large flagellates ,
for example Dinobryon, Peridinium.
The small bodied cladocerans Bosmina and Eubosmina, cyclopoid
copepods (Diacyclops), and rotifers are the major zooplankton groups in
coastal BC lakes (Rankin & Ashton, 1980). Because of low food and high
fish-grazing pressure, larger daphnids or calanoid copepods are seldom
abundant in these lakes.
Fishes
Chilean lakes have a predominance of planktonic and benthic feeding
fishes (Galaxias , Basilichthys, Aplochiton, Trichomycterus) and a low
abundance of piscivorous fish (Figure 13.2). Percas (Percichthys trucha)
were common until the introduction of rainbow trout (Oncorhynchus
my kiss) in the early 1900s. Both trout and percas in Chilean lakes have
alternative benthic prey available in the littoral zone, for example, insects,
snails, freshwater crabs, crayfish , which reduces their predation on pelagic
zooplanktivores (Soto & Zuniga, 1991).
271
Araucanian lakes. More information on bacterioplankton and autotrophic
picoplankton densities in Chilean lakes is needed before meaningful
comparisons can be made. Nonetheless, it is of interest to note that
bacteria and autotrophic picoplankton (APP) show similar density ranges
in both lake systems although APP, as is expected, reach greater densities
in the more productive Chilean lakes (Table 13.1) .
Phytoplankton
The Chilean lakes are dominated by the diatoms Aulacoseira (formerly
Melosira) and Rhizosolenia and the chrysophyceaen Dinobryon spp.
during much of the year (Campos et aI. , 1988), with a predominant spring
peak in microphytoplankton biomass and production (Campos, 1984;
Campos et aI., 1988). Cyclotella, Rhizosolenia, Aulacoseira, and Fragilaria
are the most common diatoms in BC lakes, but their abundance is very
low compared to APP, and chrysophyte, and chryptomonad nanoflagellates (Stockner, 1987). Large spring peaks of microphytoplankton biomass
and/or production do not commonly occur in coastal lakes, but at fertilized
stations within lakes sometimes they do take place (Stockner & Costella,
1980, Stockner, 1987).
Zooplankton
Zooplankton communities of Chilean lakes are dominated by Boeckellid
calanoid copepods (Boeckella gracilipes, B. michaelseni , and B. meteoris).
Also present, but less common, are the small cladoceran Neobosmina
chilensis, some cyclopoid copepods and rotifers (Soto and Zuniga, 1991).
Large copepods or cladocerans are rare, notably daphnids that are
common in most lakes of the northern hemisphere. Most of the Boeckellids are herbivorous and regulate the abundance of certain large flagellates ,
for example Dinobryon, Peridinium.
The small bodied cladocerans Bosmina and Eubosmina, cyclopoid
copepods (Diacyclops), and rotifers are the major zooplankton groups in
coastal BC lakes (Rankin & Ashton, 1980). Because of low food and high
fish-grazing pressure, larger daphnids or calanoid copepods are seldom
abundant in these lakes.
Fishes
Chilean lakes have a predominance of planktonic and benthic feeding
fishes (Galaxias , Basilichthys, Aplochiton, Trichomycterus) and a low
abundance of piscivorous fish (Figure 13.2). Percas (Percichthys trucha)
were common until the introduction of rainbow trout (Oncorhynchus
my kiss) in the early 1900s. Both trout and percas in Chilean lakes have
alternative benthic prey available in the littoral zone, for example, insects,
snails, freshwater crabs, crayfish , which reduces their predation on pelagic
zooplanktivores (Soto & Zuniga, 1991).