Erythrodynamics in Goldfish, Carassius auratus L.: Temperature Effects

Goldfish, Carassius auratus L., were acclimated to constant (con15°, con25°, and con35° C) and diurnally cycling cyc25° ± 10° C) temperature regimes or exposed to abrupt heat shock (15° to shock25° C; 25° to shock35° C). Changes in peripheral erythrocyte populations were assessed in terms of red-cell numbers, hemoglobin, hematocrit, mean erythrocytic volume and hemoglobin, cell major and minor axes, one-sided surface area, axis ratio, form factor ([4π area]/[perimeter²]) and ³H-thymidine uptake, and distribution. Temperature evoked a multicomponent response involving increased rates of erythropoiesis, karyorrhexis, and division of circulating juvenile cells. In addition, there was evidence of accelerated maturation and release of juvenile cells from storage sites. As Hb phenotype options are influenced by conditions obtaining during cell formation and/or maturation, adjustment of isomorph abundances may be achieved with minimal concomitant increase in blood viscosity and cardiac work through partial elimination and replacement of preexisting erythrocytes.