From British Columbia to northern California, coastal giant salamanders (Dicamptodon tenebrosus) are a dominant vertebrate predator in headwater streams. Though widespread, salamander health and abundance levels differ greatly between locations, provoking the question as to what factors may influence this variation and whether habitat features or biotic variables play a...
Osmotic and ionic regulation was studied in the North
American crayfish Pacifastacus leniusculus (Dana), stepwise acclimated
to increasing salinities. Stepwise acclimation involved transferring
crayfish at 48 hour intervals from freshwater to 100% seawater
in 20% increments. In experiments where 70% seawater was
used, animals were moved directly from 40 to...
Heart rates and amplitudes were measured for both intact
animals (in situ) and isolated hearts (in vitro) of the Dungeness crab,
Cancer magister, exposed to low levels in oxygen. Recordings were
also made of gill ventilation rate by measuring the frequency of
scaphognathite (gill bailer) beats.
Both the in vitro...
Osmotic and ionic regulation was studied in the Dungeness
crab, Cancer magister, after acute exposure to a range of five
salinities from 25% to 125% sea water (100% = 32%). Blood, urine
and muscle tissue were sampled at 24 and 48 hours after exposure.
Analyses were made of blood and...
The gills of an Oregon crayfish, Pacifastacus leniusculus Dana,
were examined with histological and histochemical techniques and
their fine structure was investigated by electron microscopy. Special
attention was given to the structural basis of active ion uptake.
The histology of these gills was the same as that of other crayfish...
Many environmental factors influence cardiovascular and
respiratory activities of crustaceans. The effects of natural
stressors (hypoxia, low salinity, high temperature) have been well
studied, but the effects of pollutants upon these two organ systems
have received less attention. The presence of the pesticide
carbaryl (Sevin, Union Carbide, Inc.) and its...
A central challenge for ecology is to understand the dynamic nature of species interactions. A classic approach to community ecology assumes that individuals within a species are functionally identical and that consumer-resource dynamics can be predicted solely by using species abundances. However, one species can consist of multiple functional groups,...