Effects of very short‐term formalin fixation on coral carbon and nitrogen stable isotopes, total lipids, and chlorophyll <scp> <i>a</i> </scp> and <scp> <i>c2</i> </scp> concentrations

Abstract The type of tissue preservation used in coral studies determines the type and quantity of downstream analyses that can be conducted on a given sample. Formalin is often used as a tissue preservative, but its effect on downstream analyses is unknown in coral specimens. We evaluated the effects of very short‐term (up to 3 h) formalin fixation on carbon and nitrogen stable isotopes (δ 13 C and δ 15 N) of the coral host and algal endosymbiont, total lipid concentration, and chlorophyll a and c2 (Chl a and Chl c2 ) concentrations in two coral species, Montipora capitata and Porites compressa . δ 13 C and δ 15 N values were unaffected by formalin fixation when all data from both coral species were pooled. However, when examined at the species level, P. compressa host δ 15 N was lower when fixed with formalin. Total lipid, Chl a , and Chl c2 concentrations were not altered by formalin fixation. Contrary to previous thinking, our study demonstrates that some physiological and isotopic analyses can be reliably performed on very short‐term formalin preserved coral tissue samples.