Spawning Site Selection of the Endangered Horseshoe Crab Tachyplenus Tridentatus at Tsuyazaki Cove in Fukuoka, Japan

Itaya, Shinji; Seino, Satoque; Shuuno, Mari; Sakurada, Ayumu; Koshiguchi, Ryuto

doi:10.1007/978-981-15-0291-0_131

Cited by 4 publications

(6 citation statements)

References 4 publications

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“…One of the causes is the decrease of sandy areas suitable for spawning due to coastal development . Nesting at lower elevations than the MHWN was also found in our study site (Itaya et al, 2020). Some studies point out that the survival rate of eggs in such an unfavourable environment is low (Penn and Brockman, 1994;Vasquez et al, 2015).…”

Section: Introductionsupporting

confidence: 80%

“…4 and 5). Some breeding pairs of the area laid eggs in the low intertidal zone, suggesting there was probably a shortage of suitable spawning habitat (Itaya et al, 2020). Hence, the egg survival rate of some of the breeding pairs is insufficient to sustain a viable population of horseshoe crabs in Tsuyazaki Cove.…”

Section: Impact Of Coastal Development On T Tridentatus Spawning Grou...mentioning

confidence: 99%

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Effect of Intertidal Elevation at Tsuyazaki Cove, Fukuoka, Japan on Survival Rate of Horseshoe Crab Tachypleus tridentatus Eggs

Itaya

Shuuno²,

ONIKURA

et al. 2022

J. Ocean Univ. China

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Physical factors affecting the survival of Tachypleus tridentatus eggs were investigated by translocating their eggs between the high intertidal zone and the low intertidal zone of a known spawning site. The mean egg survival rates per day were highest in the mid intertidal zone (45.1% ± 25.4%) and the lowest in the low intertidal zone (13.3% ± 27.6%). Differences in the elevation, air exposure time, and water content of the spawning ground were significant factors determining the egg survival rates. Excessive or insufficient air exposure time resulted in inadequate water content at higher and lower intertidal zones and could reduce egg survival. On the other hand, moderate saturation and dehydration were repeated with each tidal movement in the mid intertidal zone. This dynamic is considered as one of the crucial factors for the survival of eggs and is considered optimal for spawning. Therefore, the protection of the mid intertidal zone is imperative for maximizing the egg survival rate in Tsuyazaki Cove where almost all suitable nesting sites have disappeared due to coastal development. By protecting these optimal sites for spawning and recovering other optimal sites on suitable beaches, a positive contribution can be made to future management and conservation. The study also suggests that translocating eggs from marginal to optimal spawning sites might be a recovery strategy for this globally endangered species.

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Section: Introductionsupporting

confidence: 80%

Section: Impact Of Coastal Development On T Tridentatus Spawning Grou...mentioning

confidence: 99%

Effect of Intertidal Elevation at Tsuyazaki Cove, Fukuoka, Japan on Survival Rate of Horseshoe Crab Tachypleus tridentatus Eggs

Itaya

Shuuno²,

ONIKURA

et al. 2022

J. Ocean Univ. China

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“…Beach slopes can be a cue for finding spawning sites, and differences in beach slopes could stimulate horseshoe crab spawning (Nelson et al, 2019). The locations of T. tridentatus nests were on slopes of 3.29°–8.26° (Seino et al, 1998; Itaya et al, 2020), indicating that they prefer gently sloping areas. Although T. tridentatus lays eggs on sandy beaches encompassing various grain sizes, from fine to gravel, for spawning in Japan (Iida et al, 2017), nest/egg occurrence can be affected by characteristics of spawning ground sediments as demonstrated by many other horseshoe crab studies (e.g., Penn & Brockmann, 1994; Nelson et al, 2016; Botton et al, 2018).…”

Section: Methodsmentioning

confidence: 99%

Section: Environmental Data Collectionmentioning

confidence: 98%

“…Coastal development has decreased the number of breeding pairs in the study site by destroying a large area of sandy beach suitable for spawning . Nesting at lower than the MHWN was also found in Tsuyazaki (Itaya et al, 2020). Therefore, in this study, known spawning sites in Tsuyazaki Cove were evaluated in terms of their habitat suitability using scientific models.…”

Section: Introductionmentioning

confidence: 99%

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Spawning habitat suitability maps for the conservation of the tri‐spine horseshoe crab Tachypleus tridentatus in Tsuyazaki Cove, Fukuoka, Japan

Itaya

Koyama

Shuuno³

et al. 2023

Aquatic Conservation

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The suitable spawning habitat of Tachypleus tridentatus was estimated and mapped for the first time using scientific modelling in Tsuyazaki, Fukuoka, Japan. A total of 43 nests were found at five sites from 2018 to 2019. Of these 43 nests, the location information of nine nests at one of the sites was used as ‘Training data’ for constructing the models. A series of procedures was employed to determine the relationship between the biological data and their physical parameters to estimate the suitable spawning habitat. First, the contribution rates of the physical parameters (beach elevation, slope and sediment) to nest locations were evaluated. Second, physical parameters that showed significant contribution rates were chosen to estimate suitable spawning habitats. It was found that the beach elevation was the most significant parameter for estimating suitable spawning habitats. Mean high water neap to mean higher high water was estimated as suitable spawning habitat, and 74% of the nests were fitted in an area assessed as suitable. The result was consistent with previous studies. The area of suitable spawning habitat was estimated to be only 476 m2 out of 1943 m2, comprising 24% of the sandy beach in the study site. Therefore, it was concluded that the conservation and restoration of spawning grounds is a high‐priority and urgent issue at the site. It is proposed that scientific modelling of nest/egg occurrence and beach elevation can effectively determine suitable spawning habitats. Thus, it is possible to quickly establish the habitat most suitable for spawning in coastal environments and help plan conservation strategies for this globally endangered species.

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Cumulative Modifications of the Endangered Horseshoe Crab Tachypleus tridentatus Habitat by Small-Scale Developments at Tsuyazaki Cove in Fukuoka, Japan

Itaya

Wada

Shuuno³

2022

International Horseshoe Crab Conservation and Research Efforts: 2007- 2020

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Spawning Site Selection of the Endangered Horseshoe Crab Tachyplenus Tridentatus at Tsuyazaki Cove in Fukuoka, Japan

Cited by 4 publications

References 4 publications

Effect of Intertidal Elevation at Tsuyazaki Cove, Fukuoka, Japan on Survival Rate of Horseshoe Crab Tachypleus tridentatus Eggs

Effect of Intertidal Elevation at Tsuyazaki Cove, Fukuoka, Japan on Survival Rate of Horseshoe Crab Tachypleus tridentatus Eggs

Spawning habitat suitability maps for the conservation of the tri‐spine horseshoe crab Tachypleus tridentatus in Tsuyazaki Cove, Fukuoka, Japan

Cumulative Modifications of the Endangered Horseshoe Crab Tachypleus tridentatus Habitat by Small-Scale Developments at Tsuyazaki Cove in Fukuoka, Japan

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