Process of deterioration of a kelp (Ecklonia bicyclis Kjellman) bed as a result of grazing by the sea urchin Mesocentrotus nudus (Agassiz) in Shizugawa Bay in northeastern Honshu, Japan

Agatsuma, Yukio; Takagi, Satomi; Inomata, Eri; Aoki, Masakazu

doi:10.1007/s10811-018-1503-5

Cited by 9 publications

(8 citation statements)

References 25 publications

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“…However, it remains unknown of whether S. intermedius show positive or negative phototaxis in different light intensities and whether an appropriate light intensity for small S. intermedius exists. Efficient foraging is essential for the survival of the reseeded sea urchins, directly determining their productivity in the field (Agatsuma et al, 2019). 5.81 lx and 278 lx were two inflection points of daily activity rhythm of the sea cucumber Apostichopus japonicas .…”

Section: Introductionmentioning

confidence: 99%

Light intensity regulates phototaxis, foraging and righting behaviors of the sea urchin Strongylocentrotus intermedius

Sun¹,

Chi²,

Yang³

et al. 2019

PeerJ

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Small sea urchins Strongylocentrotus intermedius (1–2 cm of test diameter) are exposed to different environments of light intensities after being reseeded to the sea bottom. With little information available about the behavioral responses of S. intermedius to different light intensities in the environment, we carried out an investigation on how S. intermedius is affected by three light intensity environments in terms of phototaxis, foraging and righting behaviors. They were no light (zero lx), low light intensity (24–209 lx) and high light intensity (252–2,280 lx). Light intensity had obvious different effects on phototaxis. In low light intensity, sea urchins moved more and spent significantly more time at the higher intensity (69–209 lx) (P = 0.046). S. intermedius in high light intensity, in contrast, spent significantly more time at lower intensity (252–690 lx) (P = 0.005). Unexpectedly, no significant difference of movement (average velocity and total distance covered) was found among the three light intensities (P > 0.05). Foraging behavior of S. intermedius was significantly different among the light intensities. In the no light environment, only three of ten S. intermedius found food within 7 min. In low light intensity, nine of 10 sea urchins showed successful foraging behavior to the food placed at 209 lx, which was significantly higher than the ratio of the number (two of 10) when food was placed at 24 lx (P = 0.005). In the high light intensity, in contrast, significantly less sea urchins (three of 10) found food placed at the higher light intensity (2,280 lx) compared with the lower light intensity (252 lx) (10/10, P = 0.003). Furthermore, S. intermedius showed significantly longer righting response time in the high light intensity compared with both no light (P = 0.001) and low light intensity (P = 0.031). No significant difference was found in righting behavior between no light and low light intensity (P = 0.892). The present study indicates that light intensity significantly affects phototaxis, foraging and righting behaviors of S. intermedius and that ~200 lx might be the appropriate light intensity for reseeding small S. intermedius.

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Section: Introductionmentioning

confidence: 99%

Light intensity regulates phototaxis, foraging and righting behaviors of the sea urchin Strongylocentrotus intermedius

Sun¹,

Chi²,

Yang³

et al. 2019

PeerJ

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show abstract

Section: Introductionmentioning

confidence: 99%

“…The sea urchin Mesocentrotus nudus , is found in in kelp forests of northeast Asian seas ( Zhen, 2016 ; Agatsuma et al, 2019 ). Overgrazing by M. nudus causes deterioration of kelp beds ( Agatsuma et al, 2019 ). Therefore, it is a representative species and an ideal model to study the phenomenon of sea urchin aggregation ( Agatsuma et al, 2019 ; Agatsuma, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

High fitness areas drive the aggregation of the sea urchin Mesocentrotus nudus

Sun

Chang

et al. 2022

PeerJ

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Sea urchin aggregation is a common phenomenon in coastlines. However, it remains controversial whether sea urchins form resource aggregations or behavioral aggregations in a non-spawning season. To clarify, we studied the aggregative responses to food and predators in the sea urchin Mesocentrotus nudus when high fitness areas (HFAs) were scarce versus sufficient. By taking the occupied area of each sea urchin (test diameter + spines = 4.5 cm) as a square (4.5 cm × 4.5 cm), we set scarce HFAs for the sea urchins in Experiment 1 (the squares of HFAs: the area occupied by experimental sea urchins = 1:1) and sufficient HFAs for the sea urchins in Experiment 2 (the squares of HFAs: the area occupied by experimental sea urchins = 2:1). If M. nudus form resource aggregations, they would aggregate passively under the scarce HFAs conditions, but not in the sufficient HFAs conditions. Conversely, if M. nudus form behavioral aggregation, aggregation would occur in both scarce and sufficient HFAs. The present results showed that in the scarce HFAs, M. nudus in the food and predator groups were significantly closer to the food and further from predators, and had significantly more aggregated numbers in HFAs than those in the control group. Sea urchins did not aggregate in response to food or predators under the sufficient HFAs, although significantly more sea urchins of the experimental group was found in HFAs than that of the control group. Sea urchins (at least M. nudus) form resource aggregations that are driven by the scarce HFAs. This provides valuable information into the mechanisms of the aggregation of sea urchins.

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“…Mesocentrotus nudus is a representative marine herbivore, which distributes in kelp beds and barrens in China, Primorskyi Kray in Russia and Japan 9 . Destructively overgrazing kelps by sea urchins probably induce the transition of kelp beds to barrens 5 . Mesocentrotus nudus has obvious escape behavior in exposure to conspecific alarm cues 7 .…”

Section: Introductionmentioning

confidence: 99%

“…Future studies are essential to test the present findings in the field.Kelp beds provide food and shelters for marine organisms and thus play a key role in the marine ecosystems 1,2 . However, the transition of kelp beds to barrens occurs as a result of the overgrazing by sea urchins [3][4][5] . Sea urchins can search and subsequently destructively grasp the kelp.…”

mentioning

confidence: 99%

Foraging behavior of the sea urchin Mesocentrotus nudus exposed to conspecific alarm cues in various conditions

Chi

Yang

et al. 2021

Sci Rep

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Conspecific alarm cues crushed from Mesocentrotus nudus prevent sea urchins from foraging the kelp, but do not repel them far away from the kelp. However, it remains largely unknown of whether this phenomenon was affected by conspecific alarm cues or by the attraction of the kelp. The present study found no significant difference in the duration in the danger area with or without the kelp around conspecific alarm cues. This suggests that the phenomenon is the strategy of sea urchins but not by the attraction of kelp. We found that conspecific alarm cues appearing between the kelp and sea urchins significantly affected foraging behavior of sea urchins fasted for 21 days. This indicates that conspecific alarm cues can effectively prevent fasted sea urchins from foraging the kelp. Further, there was no correlation between foraging velocity and the duration in the danger area. Pearson correlation analysis revealed no significant correlation between foraging velocity and the duration in the safety area close to different amounts of conspecific alarm cues, suggesting that conspecific alarm cues prevent sea urchins with strong foraging ability to forage. Collectively, the present results indicate that conspecific alarm cues as highly available biological barriers are cost-effective approaches to preventing overgrazing of sea urchins in the protection of kelp beds ecosystems. Notably, the present study is a short-term laboratory investigation that does not consider the complexity of natural conditions. Future studies are essential to test the present findings in the field.

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Process of deterioration of a kelp (Ecklonia bicyclis Kjellman) bed as a result of grazing by the sea urchin Mesocentrotus nudus (Agassiz) in Shizugawa Bay in northeastern Honshu, Japan

Cited by 9 publications

References 25 publications

Light intensity regulates phototaxis, foraging and righting behaviors of the sea urchin Strongylocentrotus intermedius

Light intensity regulates phototaxis, foraging and righting behaviors of the sea urchin Strongylocentrotus intermedius

High fitness areas drive the aggregation of the sea urchin Mesocentrotus nudus

Foraging behavior of the sea urchin Mesocentrotus nudus exposed to conspecific alarm cues in various conditions

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