La présente étude fait le compte rendu des applications actuelles et des hypothèses connexes et propose des orientations futures. Toutefois, peu de chercheurs ont fait une évaluation critique des hypothèses sur lesquelles sont bassées les conclusions sur l'âge et la croissance ou ont tenu compte des modifications environnementales potentielles des caractéristiques microstructurales. RésuméĪu cours des dernières années, on a trouvé un plus grand nombre d'applications à l'examen de la microstructure des otolithes. Temperature fluctuations appear to be a primary source of subdaily increments and are a potential source of error in otolith interpretation. Increments formed as a result of the circadian rhythm (once per 24 h) may be induced by different processes than those induced through the action of environmental cues (often > 1 per 24 h), thus explaining apparent morphological differences in increment structure noted by some workers. The presence of an endogenous circadian rhythm of increment formation is invoked, entrained by photoperiod, but susceptible to modification by other cyclic environmental variables. A hypothesis of increment formation is presented which appears consistent with the numerous and often conflicting studies reported to date. Particular attention is given to the premises that the frequency of increment formation is constant and that the width of increments is proportional to fish growth. This paper reviews present applications and their assumptions and suggests future directions. However, few workers have critically assessed the assumptions upon which the age and growth inferences are based or considered the potential for environmental modification of microstructural features. Otolith microstructure examination has found an increasing number of applications in recent years.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |