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(searched for: doi:10.3354/sedao00010)
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Published: 15 April 2022
by MDPI
Sustainability, Volume 14; https://doi.org/10.3390/su14084760

Abstract:
Tropical dry forests are among the most threatened ecosystems in the world, and those occurring in the insular Caribbean are particularly vulnerable. Climate change represents a significant threat for the Caribbean region and for small islands like Jamaica. Using the Hellshire Hills protected area in Jamaica, a simple model was developed to project future abundance of arthropods and lizards based on current sensitivities to climate variables derived from rainfall and temperature records. The abundances of 20 modelled taxa were predicted more often by rainfall variables than temperature, but both were found to have strong impacts on arthropod and lizard abundance. Most taxa were projected to decrease in abundance by the end of the century under drier and warmer conditions. Where an increase in abundance was projected under a low emissions scenario, this change was reduced or reversed under a high emissions climate change scenario. The validation process showed that, even for a small population, there was reasonable skill in predicting its annual variability. Results of this study show that this simple model can be used to identify the vulnerability of similar sites to the effects of shifting climate and, by extension, their conservation needs.
Shi-Sheng Liu, ,
Journal of Crustacean Biology, Volume 41; https://doi.org/10.1093/jcbiol/ruab056

Abstract:
Land hermit crabs are widely distributed in tropical and subtropical regions, and play important roles in the coastal-forest ecosystem, such as contributing to seed dispersal and scavenging; however, they face serious threats such as habitat loss and smuggling for the exotic pet trade. Information on their reproductive biology is thus crucial for formulating and promoting conservation policies to their benefit. We conducted captive breeding for over 10 years, compiling records for four of the 10 years, and report the incubation times and frequency and the successful rate of release of larvae during captive breeding of five species of Coenobitidae: Coenobita brevimanusDana, 1852, C. cavipesStimpson, 1858, C. rugosus H. Milne Edwards, 1837, C. perlatus H. Milne Edwards, 1837, and C. purpureusStimpson, 1858. Results indicate that C. cavipes had the longest incubation period of more than 30 days and C. purpureus the shortest, approximately 20 days. Four of the species bred an average of 3.5 times per year, whereas C. cavipes bred once or twice per year. The success rate of larval release for all five species was 60%–70% over four years. Unsuccessful larval release may have been caused by human and environmental interference. Although further research is required because only small samples of each species were studied, the reported data may help to fill gaps in our knowledge on the reproductive biology of land hermit crabs.
, , Nina Yasuda, Yuki Yoshioka, Taku Sato, Yoshihisa Fujita
Published: 22 June 2020
Scientific Reports, Volume 10, pp 1-9; https://doi.org/10.1038/s41598-020-66712-4

Abstract:
Birgus latro (coconut crab) is an edible crustacean that has experienced serious overharvesting throughout its whole habitat range; however, the negative effects of overharvesting on the genetic diversity within B. latro populations have not been elucidated. Here, we report sex ratio, body size, and genetic diversity in populations of B. latro in the Ryukyu Islands where large-male–biased overharvesting of B. latro has continued. In 2 of the study populations, the sex ratio was significantly skewed toward females, and in all of the study populations large males were rare, which we attributed to sex- and size-biased overharvesting. We found no differences in genetic diversity between small and large individuals, suggesting that genetic diversity, even among the large (i.e., old) individuals, may have had already been negatively affected by overharvesting. Continued monitoring of sex ratio, body size and genetic diversity are needed for effective management of the study populations.
, Tomokazu Murakami, Akira Mizutani, Shinya Shimokawa, Hiroyoshi Kohno
Published: 1 December 2019
Marine Hydrocarbon Seeps pp 261-273; https://doi.org/10.1007/978-981-15-1129-5_16

The publisher has not yet granted permission to display this abstract.
, Xinting Lu, Zhifu Wang, Kehua Zhu, Liqin Liu, Lihua Jiang, Zhenming Lü,
Published: 23 October 2019
Genomics, Volume 112, pp 1804-1812; https://doi.org/10.1016/j.ygeno.2019.10.012

The publisher has not yet granted permission to display this abstract.
Taketo Nio, Wataru Doi, Akira Mizutani, Hiroyoshi Kohno
Crustacean Research, Volume 48, pp 67-80; https://doi.org/10.18353/crustacea.48.0_67

Abstract:
The seaward migration and larval release of Coenobita brevimanus Dana, 1852 on a sandy beach of Iriomote Island, Japan, was studied between May and November 2009 and between May and December 2010. Seaward migration and larval release were mainly observed for several days before and after new moons during the period from June to November, and the migration was mainly focused on 0.82 days after the new moon. Around full moons, some crabs were also found, with the highest numbers at 1.34 days after spring tides (semi-lunar rhythms). Almost half of the crabs that appeared on the beach entered seawater, and almost half of the immersed crabs released zoeas or exhibited swinging behavior. Appearance of crabs on the beach and entering seawater occurred only after sunset between 19:00 to 23:10. The peak time of the appearance on the beach was within a certain range each month. Crabs entered seawater at a mean of 2 h after the nighttime high tide. Seaward migration of the crabs showed clear seasonality, and many crabs migrated and entered seawater during the period from July to September, the months with higher temperature (>25°C). This species shows a phenology and rhythm of spawning common to coenobitids on the Ryukyu Islands.
Makoto Sasazuka, ,
Ethology Ecology & Evolution, Volume 31, pp 544-556; https://doi.org/10.1080/03949370.2019.1630013

Abstract:
Gastropod shells are vital resources for hermit crabs for their growth, reproduction and survival. However, the land hermit crab Coenobita spinosus, which lives in wet and dark coastal forests, sheds its shell. In the present study, to understand this unique behaviour in terms of its ecological and evolutionary aspects, we examined shell utilization and shell-shedding behaviour by C. spinosus as well as sympatric C. brevimanus as a reference. We searched for land hermit crabs during the night on the island of Guam. The shells of the crabs were grasped with the fingers and held up in the air; then, crab behaviour (shell shed or not shed), body size of the crab, and shell length were recorded. Almost all individuals of C. brevimanus occupied shells of invasive giant African snails, and the larger crabs occupied larger shells, whereas C. spinosus occupied smaller snail shells. C. spinosus also utilized nut shells and plastic caps, which were much smaller than the snail shells. Our results suggest that niche differentiation in terms of shell use might have occurred through a shift in shell utilization by C. spinosus to smaller shell types. When the shells of the crabs were held up, a large proportion of C. spinosus individuals shed their shells, whereas almost all C. brevimanus retreated into and hid in their shells. It is known that diurnal birds prey on land hermit crabs. We hypothesize that when a bird grasps a shell of C. spinosus with its bill, the crab itself could be retained within the ground debris through the shell-shedding behaviour, thereby reducing the predation risk. Our hypotheses should be tested by elucidating the original shell use habits and predator-prey interactions of C. spinosus in populations on islands without invasive snails.
Kenta Ohashi, Katsuyuki Hamasaki, Shigeki Dan, Shuichi Kitada
Crustacean Research, Volume 48, pp 1-10; https://doi.org/10.18353/crustacea.48.0_1

Abstract:
Egg loss from ovigerous females has hampered larval culture experiments for life history studies of the coconut crab Birgus latro. We conducted two preliminary experiments to develop a method to artificially incubate and hatch embryos separated from the mother: 1) manipulation of incubation duration in a pseudo-terrestrial environment and 2) manipulation of incubation temperature. In experiment 1, we incubated embryos on medical gauze moistened with seawater for 7 or 17 days at 27–28°C before incubation by immersion in seawater (27–28°C), or we continuously incubated them in seawater only. In experiment 2, we similarly incubated embryos on medical gauze until 1–2 days before hatching at 21–22°C, 24.5–25.5°C, or 27–28°C before incubation in seawater (27–28°C). Successful hatching occurred, but embryos did not hatch synchronously, and hatching continued for approximately a week. Incubating embryos in seawater continuously led to the highest hatching rates of morphologically normal zoeae; however, hatching rates of normal zoeae did not exceed 50%. Increased incubation temperature reduced the incubation duration until hatching. Zoeae could metamorphose into megalopae, but survival rates were generally low. Further studies are required to improve the hatching rate of viable larvae under artificial conditions.
Katsuyuki Hamasaki, Ei Saeki, Kotomi Mizuta, Masaru Tanabe, Ikumi Yamazaki, , Shunsuke Fujikawa, ,
Crustacean Research, Volume 47, pp 101-110; https://doi.org/10.18353/crustacea.47.0_101

Abstract:
Salinity is an important ecological factor affecting larval survival and development of coastal and estuarine decapod crustaceans. We investigated the low salinity tolerance limits of larvae in the six terrestrial hermit crab species, the coconut crab Birgus latro, and the land hermit crabs Coenobita brevimanus, C. cavipes, C. purpureus, C. rugosus, and C. violascens to infer their early life history strategies. Zoeae and megalopae were exposed to six different salinity levels ranging from 5–30 ppt with intervals of 5 ppt for 24 h, and the median lethal salinity (MLS) was estimated as the salinity at which 50% of test larvae died. The MLS estimates were lowest in the first zoeae, increased during the zoeal stage, and declined in the megalopal stage in all species. Early zoeae and megalopae were euryhaline and later zoeae stenohaline, suggesting that coenobitids exhibit a larval export strategy towards the offshore (oceanic) marine waters. Interspecific variation was evident in the salinity tolerance of the first zoeae, probably reflecting the salinity conditions at the species-specific larval hatching place. In contrast, the low salinity tolerance ability of megalopae did not differ among species, suggesting that coenobitid megalopae might require similar habitats for the settlement and initiation of benthic life.
Published: 19 February 2018
by SciELO
Abstract:
Shell occupation by the land hermit crab Coenobita violascens Heller, 1862 was investigated from January 2011 to March 2012 on Phuket Island in the Andaman Coast of Thailand. The samples of C. violascens were collected monthly using multiple quadrat sampling. Twenty shell species from 11 families were found occupying by C. violascens, which were mainly marine gastropods (90%). The three most common occupied shell species were Chicoreus brunneus (Link, 1807) (21.3% of hermits), followed by Filifusus filamentosus (Röding, 1798) (14.9%) and Laevistrombus canarium (Linnaeus, 1758) (14.9%). Biconical shells and those with ovate apertures were the most commonly occupied shell types. Furthermore, individual C. violascens probably occupy the shells of at least three different gastropod species during their lifetime. Interestingly, C. violascens shows a tendency of occupying specific categories of shells in relation to shell species, shape and aperture shape. Other aspects of shell occupation by C. violascens compared to congeneric species are also discussed.
Wataru Doi, Akira Mizutani, Hiroyoshi Kohno
Published: 1 January 2018
Crustaceana, Volume 91, pp 199-211; https://doi.org/10.1163/15685403-00003758

Abstract:
The larval release behaviour of Coenobita cavipes Stimpson, 1858 was studied on Iriomote Island, Japan between June and September 2012. The larval release was observed for several days before and after the new and full moons between July and August and showed semi-lunar rhythms. The larval release occurred 1-3 h after sunset and the peak time was almost 30 min earlier in August than in July. The time was not synchronised with nocturnal high tides in earlier and later days in each phase of syzygy. Emerging from residual lowland forests behind the coast, ovigerous females walked towards the river’s water edge and released larvae at the swash zone on the riverbank in the lower river. Therefore, they do not need to synchronise the larval release to coincide with the timing of high tide, unlike their congeneric nearest neighbour, C. violascens Heller, 1862, which releases larvae on the mangrove roots in the upper river.
Katsuyuki Hamasaki, Shunsuke Fujikawa, Chikako Iizuka, , Takuma Tsuru, ,
Published: 26 November 2017
Invertebrate Biology, Volume 137, pp 3-16; https://doi.org/10.1111/ivb.12198

The publisher has not yet granted permission to display this abstract.
Katsuyuki Hamasaki, Takahiro Matsuda, Ken Takano, Mio Sugizaki, Yu Murakami, Shigeki Dan,
Published: 24 August 2016
Aquatic Biology, Volume 25, pp 83-96; https://doi.org/10.3354/ab00663

Katsuyuki Hamasaki, Sora Hatta, Takuma Ishikawa, Shota Yamashita, Shigeki Dan,
Published: 20 November 2015
Invertebrate Biology, Volume 134, pp 318-331; https://doi.org/10.1111/ivb.12107

The publisher has not yet granted permission to display this abstract.
Katsuyuki Hamasaki, Ayaka Sugimoto, Asuka Ojima, Chikako Iizuka, Mio Sugizaki, , Shigeki Dan
Journal of Crustacean Biology, Volume 35, pp 793-803; https://doi.org/10.1163/1937240x-00002370

Abstract:
We evaluated the genetic diversity and demographic history of the terrestrial hermit crabs Birgus latro and Coenobita brevimanus using mtDNA COI sequence data (573 bp). Tissue samples from 163 individuals of B. latro and 63 individuals of C. brevimanus were collected at 11 and four localities in the North-Western Pacific Region, respectively. Haplotype diversity was high and similar in B. latro (0.8809) and C. brevimanus (0.9222). Nucleotide diversity was higher in C. brevimanus (0.01088) than in B. latro (0.00404). No genealogical structure was observed in haplotypes of B. latro whereas four haplotype clades were found in C. brevimanus. Weak but significant genetic population structure with the isolation by distance was detected in B. latro, but no genetic population structure was observed in C. brevimanus, likely because of the small number of sampling localities for the latter. Demographic history analyses suggested that B. latro and C. brevimanus had different histories of population expansion. Birgus latro experienced population expansion once during the glacial period when sea levels were relatively lower in the late Pleistocene. Conversely, it was inferred that haplotype clades of C. brevimanus diverged during or near the interglacial period when sea levels were relatively higher, and their population expansion and remixing occurred through the glacial periods in the late Pleistocene.
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