Growth and gonad production of the sea urchin Hemicentrotus pulcherrimus in the fucoid bed and algal turf in northern Japan

Abstract

To clarify the differences in the growth and gonad size of the sea urchin Hemicentrotus pulcherrimus among algal sere, the study was conducted in June and July, and September 1998 at three fucoid beds in Oga and at three algal turfs in Hachimori, Akita Prefecture in northern Japan. The most rapid growth was observed in a large perennial fucoid bed at the climax stage. Growth in a small perennial Chondrus ocellatus‐dominated bed in algal turfs in the seral stage was then high. The slowest growth was observed in the small perennial Dictyopteris divaricata‐ and Laurencia spp.‐dominated beds which are known to possess chemicals which act as feeding deterrents against the sea urchins. The gonad index (gonad wet weight × 100/body wet weight) at a fucoid bed was high where standing crops exceeded 3 kg·m−2. The gonad index in the Laurencia bed was lower than those at fucoid beds. These results suggest that growth and gonad production are affected by algal sere and differ among species of small perennial algae in the seral stage with or without chemical defense.

Population Dynamics of Edible Sea Urchins Associated with Variability of Seaweed Beds in Northern Japan

“…Endo et al (2007) studied the vertical distribution and food of M. nudus and H. pulcherrimus in fucoid beds and concluded that foods such as sessile animals ensure the gonad development of M. nudus in coralline flats, eliminating the migration of the sea urchin to fucoid beds in shallow waters. Seasonal maximum gonad indices of H. pulcherrimus in coralline flats and fucoid beds were 11, markedly lower than those in fucoid beds at other localities (Agatsuma and Nakata 2004;Agatsuma et al 2005a). This suggests that H. pulcherrimus ingest the dominant foods.…”

“…For H. pulcherrimus, the seasonally maximum gonad index were more than 20 in Sargassum bed (Agatsuma and Nakata 2004), and the kelp bed dominated by Undaria pinnatifida and Saccharina japonica (Ogasawara et al 2011), 18.5 in Acrosorium polyneurum bed (Agatsuma et al 2006b), 18 in E. bicyclis bed (Agasuma et al 2012) and 10-11 in barrens (Agatsuma et al 2006b;Endo et al 2007). By contrast, in the fucoid beds dominated by the large fucoids Myagropsis myagroides, Sargassum piluliferum and Sargassum patens, the maximum gonad index was 9.8, which is markedly low (Endo et al 2007).…”

“…and Chondrus ocellatus (Agatsuma et al 2005a) (Table 2). Namely, the growth rates of S. nudus in kelp beds are higher than those in fucoid beds.…”

“…Using the same method of age determination, which can be applied for H. pulcherrimus (Agatsuma and Nakata 2004), the sea urchins reached 3 cm diameter after approximately 3 years in a Sargassum bed (Agatsuma and Nakata 2004), a fucoid bed dominated by C. langsdorfii, S. piluliferum and S. patens bed (Agatsuma et al 2005a), a U. pinnatifida and S. japonica bed (Ogasawara et al 2011) and an E. bicyclis bed (Agatsuma et al 2012) and more than 3 years in the beds of the red algae Dictyopteris divaricate, Laurencia spp. and Chondrus ocellatus (Agatsuma et al 2005a) (Table 2).…”

Food of the sea urchins Strongylocentrotus nudus and Hemicentrotus pulcherrimus associated with vertical distributions in fucoid beds and crustose coralline flats in northern Honshu, Japan

“…Pearse 1980, Meidel & Scheibling 1998, Agatsuma et al 2005a. The most rapid growth and highest gonad production are found in laminarian beds, followed by algal turf, consisting mainly of red algae such as Chondrus ocellatus.…”