Title

A COMPARATIVE STUDY OF RESPIRATION DURING EARLY DEVELOPMENT OF THREE MARINE COTTIDS

Date of Completion

January 1986

Keywords

Biology, Ecology

Degree

Ph.D.

Abstract

Effects of temperature, salinity and photoperiod on respiration during early development of three cottids were studied. Eggs of grubbies, Myoxocephalus aenaeus, longhorn sculpins, M. octodecemspinosus, and sea ravens, Hemitripterus americanus, were fertilized and developed in salinities ranging from 12.5-35 ppt (grubbies), 15-35 ppt (longhorns), and 20-35 ppt (sea ravens), in temperature-controlled baths at 2C, 5C, 8C (Myoxocephalus) and 8C, 11C, 14C (Hemitripterus). Oxygen consumption of individual grubby, longhorn sculpin and sea raven eggs increased with age and temperature. Oxygen consumption during embryogenesis was independent of salinity. Endogenous rhythms of oxygen consumption were not apparent.^ Multiple regression models were developed, and indicated that metabolism during embryogenesis of the two genera differed markedly. Myoxocephalus embryos increased oxygen consumption due to age and interaction of temperature and age. Grubby embryos exhibited metabolic cold adaptation, compared to longhorn sculpins. Respiration in sea raven embryos increased with age and varied in a linear and curvilinear manner with temperature. Embryonic overwintering may represent a response to temperature and age. Residuals from the regression models demonstrated that oxygen consumption of gastrulae can be highly variable, development of blood is important in both genera and embryonic oxygen consumption is affected by activity and duration of the prehatch stage. An hypothesis suggesting that incubation in cold conditions should be favorable for demersal embryos is presented.^ Oxygen consumption by prolarvae of Myoxocephalus declined during yolk absorption. The species exhibited different respiratory responses to salinity and alterations of temperature. Individual variation masked temperature and salinity effects on oxygen consumption by sea raven prolarvae, but decline of oxygen consumption during yolk absorption was significant.^ Separation of grubbies and longhorn sculpins into estuarine and coastal spawning habitats, respectively, is promoted by low salinity tolerance of eggs, metabolic adaptation of embryos and temperature-salinity responses of larvae.^ Variation in oxygen consumption by eggs and larvae was large and increased with rates of uptake. Variation in reproductive success of fishes may reflect the influences of abiotic factors on the metabolism of embryos and prolarvae, by affecting size at hatching or duration of yolk absorption. ^