MARTELL, D.J.*; TRIPPEL, E.A.; KIEFFER, J.D.; Univ. of New Brunswick/St. Andrews Biological Station; St. Andrews Biological Station; Univ. of New Brunswick: The effects of temperature on haddock (Melanogrammus aeglefinus) muscle development through ontogeny

Development in fish is not a static process as events are tightly interlinked and highly reliant on environmental variables, such as temperature. As part of a larger project, this study documents the effect of temperature on muscle development throughout ontogeny, from embryonic to pelagic juvenile stages in haddock (Melanogrammus aeglefinus). To determine the effect of temperature on muscle development, eggs were incubated at 5 temperatures (2, 4, 6, 8, 10&degC) and, after hatching, reared at 6&degC for 50 days. A series of morphological �landmarks� representative of general organismal and specific muscle development were established to reference developmental variation. These landmarks were determined through examination of changes in various tissues and the whole organism. Landmarks were used as reference points to determine developmental variability among temperatures. Development to hatch was found to be inversely proportional to incubation temperature ranging from 10 days at 10&degC to 24 days at 2&degC. Although larvae from all temperatures appeared to hatch at the same developmental stage, muscle development was affected by incubation temperature. The size of deep muscle cells was found to vary proportionately with temperature. However throughout all muscle layers, muscle cell number, fibre density, and mitochondrial number varied inversely with temperature. Such differences among temperature groups persisted beyond 20 days post-hatch.