Japanese anchovy egg accumulation at the sea surface or pycnocline—Observations and model |
| |
Authors: | Yuji Tanaka |
| |
Institution: | (1) Faculty of Agriculture, Kinki University, Nakamachi, 631 Nara, Japan |
| |
Abstract: | Near surface vertical distributions of Japanese anchovy eggs (isolated and pelagic) were studied at western Wakasa Bay, Japan. Samples were collected in horizontal tows with four plankton nets simultaneously operated at different four depths of 0, 0.5, 1.0, and 2.0 m. The egg concentration was found to decrease exponentially with depth. The egg concentration profile can be explained by considering the balance of the eggs' ascent and vertical diffusion. Taking further into account vertical difference in rising/sinking rates of the eggs, a clear accumulation of the eggs on a pycnocline, observed elsewhere, also can be explained. Vertical eddy diffusivity in the surface layer in a calm sea was 1–10 cm2 s–1, as estimated from the egg concentration profile and the velocities of the eggs in the vertical direction. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|