| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2002: ¥2,700,000 (Direct Cost: ¥2,700,000)
|
|---|
| Research Abstract |
We collected organisms quantitatively at the various sized seagrass beds in Notoro Lagoon, Hokkaido, and detected negative correlation between patch sizes and densities in the most animals. The pandalid shrimp Pandalus latirostris inhabited in the seagrass beds at daytime, while they appeared in the sand flat around the seagrass beds at nighttime. Potential predatory fishes showed no clear daily distributional pattern. We found the same pattern in the artificial seagrass beds as the natural ones of the negative correlation between patch sizes and shrimp densities. There were no changes in water temperature, salinity and water velocity among various sized artificial seagrass beds. We compared the shrimp densities among the differently-arranged artificial seagrass beds within the same total patch area, and smaller patches area showed higher densities than the larger patch area. As a conclusion, in the context of the debate of single large or several small patches (SLOSS debate), several small patches showed higher densities of the shrimp in the seagrass beds, which is contrary to the tendency detected in the terrestrial communities. I suggest that marked daily movement pattern shown in the pandalid shrimp accounts for the observed distribution pattern ; even daily coming from and going into the seagrass beds of the shrimp might be random, they may show higher encounter rates to the smaller patches because of higher edge-to-interior ratio.
|
