Revista Chilena de Historia Natural 80 (4): 439-446, 2007
RESEARCH ARTICLE
Inter-population thermal variability and physiological response in the intertidal fish
Scartichthys viridis (Blenniidae)
Determining habitat conditions that generate individual physiological variability represents
key basic knowledge to understand the direction of animal’s responses to habitat change. The coastal fish Scartichthys
viridis inhabits low intertidal pools along the Chilean coast. Because seawater in the low intertidal is renewed during every
tidal cycle, this zone is characterized by a low thermal variation and abundant food within and between localities. We evaluated
whether seawater thermal conditions and food availability of low intertidal pools registered in three localities of Chilean coast are
sufficient to generate physiological and energetic differences in individuals of S. viridis captured from three geographic
separate populations spanning approximately 1,200 km. Southern fishes acclimatized to 25 ºC showed higher metabolic
rates than those from other localities and thermal treatments. On the other hand, southern fishes in natural conditions showed higher
condition factor than northern fishes. This evidence is sufficient to indicate that slight latitudinal differences in tidepool seawater
temperature associated to differential food availability induced an energetic constraint in this species. Moreover, southern population of
S. viridis may suffer important effects on energetic allocation if seawater temperature increases slightly, with
repercussions on its geographic distribution in southern Pacific Ocean.
Key words:
intertidal fish,
physiological compensation, tidepool, Scartichthys viridis
