Schreckstoff - Ecological Considerations

Ecological Considerations

The most convincing research to date indicates that alarm substance cells serve as an immune system response and that the ecological ramifications of this substance as a chemical alarm signal developed subsequently. This finding generates a number of interesting research questions. First, as mentioned earlier, males in many ostariophysan species cease production of alarm substance cells during the breeding season, presumably so that females are not inadvertently repelled from the nest when males incur mechanical damage during nest building. In light of the immune hypothesis, it is possible that alarm substance cells are instead produced less during the breeding season because increased testosterone levels may decrease immune responses (Folstad and Karter 1992). Additionally, this finding indicates that males are at a greater risk from UVB radiation as well as parasite and pathogen infection during the breeding season.

The role of schreckstoff as an immune response has additional implications in this age of increasing environmental change (Chivers et al. 2007). Environmental stressors, including UVB radiation, pollution and parasites, are increasing in the environment and are likely to continue increasing over time. UVB radiation exposure is increasing due to decreases in stratospheric ozone (Blaustein et al. 1997), diseases are becoming increasingly important at both local and global scales (Kiesecker et al. 2004) and pollutants, including heavy metals, are being introduced into ecosystems (Jenson & Bro-Rasmussen 1992). If cadmium, the heavy metal affecting the fishes’ ability to produce schreckstoff in response to environmental stressors, increased in concentration in the environment, the immune response of many Ostariophysan fishes would be compromised (Chivers et al. 2007).