What I'm really interested in people's livestock experience in tanks hitting higher temp. The general wisdom in anything over ~82 is bad and everyone seems to do what they can to keep temp below this, but I'm wondering if there is much direct experience to back up this concern. I just did a quick google search to find some science on this - here's a few abstracts below. Of course most of the research is concerned with the effect of ocean warming on reefs, rather than aquariums on hot days, but Shimek has a nice article
http://web.archive.org/web/20030218...om/fish2/aqfm/1997/nov/features/1/default.asp
Effects of temperature on the mortality and growth of Hawaiian reef corals
P. L. Jokiel and S. L. Coles
Abstract Three common species of Hawaiian reef corals, Pocillopora damicornis (L.), Montipora verrucosa (Lamarck) and Fungia scutaria Lamarck, were grown in a temperature-regulated, continuous-flow sea water system. The skeletal growth optimum occurred near 26?C, coinciding with the natural summer ambient temperature in Hawaii, and was lowest at 21? to 22?C, representing Hawaiian winter ambient. Levels of approximately 32?C produced mortality within days. Prolonged exposure to temperatures of approximately 30?C eventually caused loss of photosynthetic pigment, increased mortality, and reduced calcification. Corals lived only 1 to 2 weeks at 18?C. The corals showed greater initial resistance at the lower lethal limit, but ultimately low temperature was more deleterious than high temperature. Results suggest that a decrease in the natural water temperature of Hawaiian reefs would be more harmful to corals than a temperature increase of the same magnitude.
Effect of temperature and temperature adaptation on calcification rate in the hermatypic coral Pocillopora damicornis
C. D. Clausen and A. A. Roth
Abstract Using 45Ca incorporation into the coral skeleton as a measure of calcification rate, the effect of temperature on clacification rate was studied in the hermatypic coral Pocillopora damicornis. Both immediate and long-term (adaptation) effects were investigated. Temperature has a marked effect on rate ? an effect that varies depending on the temperature history of the coral (i.e., temperature adaptation occurs). P. damicornis showed both 27? and 31?C temperature optima, one or the other being dominant depending on the natural water temperature to which the coral was adapted. The two optimum temperatures may indicate two isoenzymes or two alternate metabolic pathways involved in the calcification process.
Synergistic effects of temperature, salinity and light on the hermatypic coral Montipora verrucosa
S. L. Coles and P. L. Jokiel
Abstract Temperature tolerance in the reef coral Montipora verrucosa (Lamarck) is affected by salinity and light. Low salinity reduces ability of the coral to survive shortterm exposure to elevated temperature. High natural light intensity aggravates damage sustained by corals at high temperature. In long-term growth experiments, high light intensity caused substantial loss of zooxanthellar pigment, higher mortality rates, reduced carbon fixation and lowered growth rate at both upper and lower sublethal temperatures Effects of light at optimal temperature were less dramatic. Interactions between physical environmental factors appear to be most important near the limits of tolerance for a given factor. Acclimation capability was indicated, and was influenced by both thermal history and pigmentation state of stressed corals.
I take away from all this that anything under 86F, at least in the short term, is probably fine, and hitting 90 is where you'll really start to see an effect. The main impact seems to be bleaching - there's no data on softies, but perhaps softie-only tanks may be less of a concern at high temps.
