Ontogeny of respiratory area of a marine teleost, porgy,pagrus major

Abstract

Relationships of respiratory areas (gill, body surface and fin areas) (A) to body mass (W) were determined with a marine teleost, the porgyPagrus major of 0.0002–1230 g (just after hatch to 3+ years old), based on the allometric formula A=αWβ. (1) Early larvae (0.0002–0.0003 g) did not have the secondary lamellae that were responsible for gas exchange at the gills. After this stage, a tetraphasic relationship was observed between lamellar area (total area of secondary lamellae, often called gill area) (GAL) and boby mass. During the late larval and early juvenile stages, the GAL-W relationship showed a triphasic positive allometry with β-values of 3.773, 1.561 and 1.111 corresponding to the first half of the late larval stage (0.00034–0.001g), the second half of the stage (0.001–0.01 g) and the early juvenile stage (0.02–0.1 g), respectively, During the squamated juvenile and later stages (0.1–1080g), there was a negative allometry with a β-value of 0.813. (2) A triphasic relationship was observed between the total cutaneous surface area (body surface area and fin area) (CAb+f) and body mass. During the early larval stage, in which an increase of body mass was very small. from 0.0002 to 0.00025 g, CAb+p/W increased with growth with a β-value of 3.986. After this stage, the CAb+t W relationship showed a diphasic negative allometry with β-values of 0.562, during the late larval stage (0.00028–0.0045 g) and 0.652 during the early juvenile and later stages (0.0045–1230 g). (3) Based on these results, factors controlling the metabolism-size relationship are discussed.