How do tropical seagrass beds function as habitats for fishies?

2003 Fiscal Year Final Research Report Summary

• Project/Area Number: 14560141
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: General fisheries
• Research Institution: The University of Tokyo
• Principal Investigator: SANO Mitsuhiko The University of Tokyo, Graduate School of Agricultural and Life Sciences, Associate Professor, 大学院・農学生命科学研究科, 助教授 (50178810)
• Project Period (FY): 2002 – 2003
• Keywords: seagrass bed / coral area / artificial seagrass unit / fish assemblage / Iriomote Island

Research Abstract

To determine fish assemblage structure in tropical seagrass beds and how its structure differs from those in adjacent coral and sand areas, visual censuses were conducted at Amitori Bay, Iriomote Island, Japan, in August and November 2002. five 1m×20m transects were established at each habitat (seagrass bed, coral area, and sand area), and all fishes within the transect area were counted.the numbers of species and individuals of fishes were higher in the coral area than in the seagrass bed and sand area.
To clarify the effects of changes in seagrass leaf density and height on recruitment of the cardinalfish Cheilodipterus quinquelineatus, which is a common species in troical seagrass beds, a field experiment using artificial seagrass units (ASUs, including (1)long dense leaves (LD-units), (2)long leaves thinned to about 40% of LD-unit density, (3)dense leaves shortened to 40% of LD-unit height, and (4)no leaves (control), were used, recruits on each ASU being counted daily over 14 consecutive days. The mean number of C. Quinquelineatus recruits per replicate on LD-units was significantly greater than on the other unit types, indicating that longer denser seagrass leaves had a significant impact on recruitment of the species.