2017 旭硝子財団 助成研究発表会 要旨集

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1. 2. 7201710001 1 Henmi et al., Henmi et al.,2017a 237Quantication of use of burrows in aquariaTo quantify the pattern of the use of N. japonica burrows by S. toriumii, experiments were performed from October 2013 to January 2014 as described by Henmi & Itani (2014b), who quan-tied the use of U. yokoyai burrows by S. toriumii. The experi-ments with N. japonica were performed in narrow acrylic tanks (50 × 200 × 300 mm high) that were covered with opaque vinyl chloride sheets to exclude light. The tanks were lled with muddy sand to around 200 mm in height, and were then covered with water to a depth of about 100 mm. A single N. japonica was intro-duced into each tank and allowed to construct a burrow (Fig. 1). Twelve shrimp (8 males and 4 females) of 5.6–10.2 mm carapace length were used. The tanks were placed in large aquaria with cir-culating seawater for at least 4 days until the burrow was complete. Burrow conditions and survival of N. japonica were conrmed by removing the vinyl chloride sheet. The experimental tank was taken out from the large aquarium when used for recording. The experiments with M. banzai were performed from November 2014 to January 2015. Since the crabs were not able to construct their burrows in narrow tanks, aquaria (180 × 220 × 260 mm high) lled with mud to a height of around 80 mm were used in these experiments. Water depth was about 10 mm because muddy water interferes with observations. Six crabs (3 males and 3 females) of 13.2–18.6 mm carapace width were used. Burrow conditions and survival of M. banzai were conrmed daily by surface activity of individuals.When each experimental condition was satised, a single speci-men of S. toriumii was placed inside each experimental tank, and the sediment surface was immediately recorded using a video camera (Canon Ivis HFM51 or HFR21). The behavior of the crab was recorded during the day under articial illumination (about 2.8 k lx), with each session lasting 2 h. The camera was set approximately 30 cm over the tank using a tripod. The tank was not aerated during recording because air bubbles disrupt the water surface. The tank was nevertheless aerated between recording ses-sions when not in use in the experiment. Twenty individuals of S. toriumii (8 males, 12 females), 2.9–6.1 mm carapace width, were used in the tanks containing burrows of N. japonica. Twenty-eight individuals (13 males, 15 females), 3.9–6.2 mm carapace width, were used for the M. banzai burrows. Individuals of S. toriumii were randomly assigned to the experimental tanks containing M. banzai burrows, which were large enough for the S. toriumii individuals to enter.The burrow-entering behavior of S. toriumii was studied from video recordings. Data included the time taken to enter a bur-row the rst time, the number of instances of burrow entering sessions,crab burfrom immwere regses. Obsindividuburying periods, in the pr2014b). for feediBehaviorTo obserwere forin transpJanuary the two umade usa 5 cm gebiid Uable to tall parts tubes, wting (1 mthe crabA singa host shbehaviorthe tranor HFRmales andomly a3 femalemales andomly a3 femalemales andomly afemales, ance behceans waSestrosThe rs>2 cm fing undethus mowas the tubes.StatisticaThe abulocationswith StenormallyThe dthose froU. yokoyaviduals umost anused burover twothe databurrow ution of btotal timFigure 1. Experimental setup to examine burrow use by Sestrostoma toriumii. 2 2−208−発表番号　99　〔中間発表〕