Human disturbance affects behavioural time allocation in a fiddler crab (Austruca annulipes) in Southern Thailand

Human disturbances affect the macroinvertebrate populations in coastal regions. They respond to disturbances by altering their density and behaviour. Therefore, many of them are used as bioindicator species of human disturbance. Here, we pioneer the use of fiddler crabs to examine whether they alter their behaviour under human disturbance. Male fiddler crabs possess one large claw used for courting (waving) and fighting, and one small feeding claw, whereas females have two feeding claws. They show several surface activities. This study investigates (1) the effects of human disturbance on density and sex-ratio, and (2) the effects of human disturbance, and sex on behavioural time allocations in Austruca annulipes. Their density, sex-ratio, and time allocations were investigated in human-disturbed area (DA) and nondisturbed area (NDA). They showed feeding, feeding and walking, walking, running, standing/vigilance, inside burrows, burrowing, grooming, fighting, and waving. The results showed that crab density was higher and the sex ratio was more male biased in NDA than in DA. Human disturbance and sex affected time allocations but their interaction had no effect. Crabs in DA spent more time running, standing, and inside burrows but less time walking, burrowing, fighting, and waving than crabs in NDA. Between sexes, males spent more time standing, burrowing, grooming, and fighting but less time feeding, and walking than females. This indicates that human disturbances force the crabs to spend more time on anti-predator and escape behavior (standing/vigilance, running, inside burrows) rather than courting (waving) and constructing burrows (mating/breeding sites), which are important for breeding.(AU)

Temporal variations in the air, soil, and fiddler crab (Austruca perplexa) burrow temperatures in southern Thailand

Fiddler crabs live in an intertidal habitat and face several environmental constraints. Extreme environmental conditions, especially temperature affects their growth and reproduction. They use several strategies to deal with extreme temperatures. Among these, constructing burrows is important. Burrows act as a refuge during very high or low temperatures. This study investigates the temporal variations in air temperature, burrow temperature of large-sized male and female Austruca perplexa crabs, and the soil temperature near their burrows in Nakhon Si Thammarat province, southern Thailand (tropical climate). Air, burrow and soil temperatures were measured every 30 min in a day using temperature sensors. We observed that from 8:00 up to and including 17:30, burrow temperature was lower than soil temperature, but other times, burrow temperature was higher than soil temperature. In the case of air temperature, it was lower than soil or burrow temperatures most of the time in a day. When we compared temperatures among air, soil, and burrows at day (6:00 up to 17:30) and night (18:00 up to 5:30), burrow temperature was lower than soil temperature during the day but was higher at night. The air temperature was lower than soil or burrow temperatures on both day and night. This study shows that A. perplexa crab burrows can modulate the inside temperature and maintain a suitable temperature for the crabs.(AU)

Temporal variations in the air, soil, and fiddler crab (Austruca perplexa) burrow temperatures in southern Thailand

Fiddler crabs live in an intertidal habitat and face several environmental constraints. Extreme environmental conditions, especially temperature affects their growth and reproduction. They use several strategies to deal with extreme temperatures. Among these, constructing burrows is important. Burrows act as a refuge during very high or low temperatures. This study investigates the temporal variations in air temperature, burrow temperature of large-sized male and female Austruca perplexa crabs, and the soil temperature near their burrows in Nakhon Si Thammarat province, southern Thailand (tropical climate). Air, burrow and soil temperatures were measured every 30 min in a day using temperature sensors. We observed that from 8:00 up to and including 17:30, burrow temperature was lower than soil temperature, but other times, burrow temperature was higher than soil temperature. In the case of air temperature, it was lower than soil or burrow temperatures most of the time in a day. When we compared temperatures among air, soil, and burrows at day (6:00 up to 17:30) and night (18:00 up to 5:30), burrow temperature was lower than soil temperature during the day but was higher at night. The air temperature was lower than soil or burrow temperatures on both day and night. This study shows that A. perplexa crab burrows can modulate the inside temperature and maintain a suitable temperature for the crabs.

Embryonic development of a mountainous fish species Garracambodgiensis (Tirant, 1883) in southern Thailand

This study examined the artificial breeding and embryonic development of a mountainous fish species Garra cambodgiensis (Tirant, 1883) found in Promlok waterfall in Khaoluang National park, Phromkhiri district, Nakhon Si Thammarat province. The fishes were collected from June 2017- January 2018 and kept in aquaria. Afterward, the brood males and females were selected and injected with buserelin (LHRHa) (10 µg/kg body weight) and domperidone (10 mg/kgbody weight). After the injections, both females and males were kept together in the water at a proportion of 3 females: 1male. The fertilization of eggs started after 4 hours and 30minutes. The fertilized eggs were greenish-grey and semi-buoyant. After fertilization, one blastodisc turned into 2 equalsized blastomeres, and then each cell divided into 4, 8, 16, 32,64 cells respectively. The morula stage went to the blastula stage in about 3hr and 28 min, to gastrula stage in about 5 hr and 11 min, and to the somite stage in about 7 hr and 7 min. The optical vesicles and auditory vesicles developed after approximately 8 hr and 27 min, and 10 hr and 30 min, respectively. After approximately 12 hours and 58 minutes of fertilization, hatching of eggs occurred. Nowadays, the numbers of G. Cambodgienesis are declining rapidly in southern Thailand due to several environmental and anthropogenic reasons. Therefore, it is very important to conserve the populations of G. Cambodgienesis. Artificial breeding could be an effective way to conserve and restore this fish in their natural habitat in southern Thailand.(AU)

Embryonic development of a mountainous fish species Garracambodgiensis (Tirant, 1883) in southern Thailand

This study examined the artificial breeding and embryonic development of a mountainous fish species Garra cambodgiensis (Tirant, 1883) found in Promlok waterfall in Khaoluang National park, Phromkhiri district, Nakhon Si Thammarat province. The fishes were collected from June 2017- January 2018 and kept in aquaria. Afterward, the brood males and females were selected and injected with buserelin (LHRHa) (10 µg/kg body weight) and domperidone (10 mg/kgbody weight). After the injections, both females and males were kept together in the water at a proportion of 3 females: 1male. The fertilization of eggs started after 4 hours and 30minutes. The fertilized eggs were greenish-grey and semi-buoyant. After fertilization, one blastodisc turned into 2 equalsized blastomeres, and then each cell divided into 4, 8, 16, 32,64 cells respectively. The morula stage went to the blastula stage in about 3hr and 28 min, to gastrula stage in about 5 hr and 11 min, and to the somite stage in about 7 hr and 7 min. The optical vesicles and auditory vesicles developed after approximately 8 hr and 27 min, and 10 hr and 30 min, respectively. After approximately 12 hours and 58 minutes of fertilization, hatching of eggs occurred. Nowadays, the numbers of G. Cambodgienesis are declining rapidly in southern Thailand due to several environmental and anthropogenic reasons. Therefore, it is very important to conserve the populations of G. Cambodgienesis. Artificial breeding could be an effective way to conserve and restore this fish in their natural habitat in southern Thailand.

Seasons and water container types affecting Culex spp. in Southern Thailand

Usually, Culex mosquitoes are responsible for spreading several human diseases such as malaria, Japanese encephalitis, yellow fever, filariasis, and Zika. Lymphatic filariasis and Zika cases are increasing in Thailand with more prevalent in southern Thailand. In this study, our aim is to examine how seasons and water container types affect Culex spp. larvae numbers in Lansaka district, Nakhon Si Thammarat province, southern Thailand. This study was conducted in five sub-districts (Lansaka, Khaokaew, Thadi, Kamlon, and Khunthale) in Lansaka district. In each subdistrict, 120 houses were randomly selected to study the breeding sites of Culex mosquito in dry (March-May, 2018) and wet (October-December, 2018) seasons. Mosquito larvae were collected from indoor, outdoor, natural, artificial, darkcoloured, light-coloured, with lid, and without lid containers. It was observed that in all sub-districts, Culex larvae numbers were higher in dry season compared to wet season. In both seasons, outdoor, without lid, dark-coloured, and artificial containers contained more Culex larvae than inside, with lid, light-coloured, and natural containers, respectively. This study shows that seasons and water container types affect Culex mosquito larvae. Since the larvae numbers are higher in dry season, as well as in outdoor, without lid, dark-coloured, and artificial containers, people should reduce the usage of these containers, especially in the dry season, to prevent Culex borne diseases.(AU)

Seasons and water container types affecting Culex spp. in Southern Thailand

Usually, Culex mosquitoes are responsible for spreading several human diseases such as malaria, Japanese encephalitis, yellow fever, filariasis, and Zika. Lymphatic filariasis and Zika cases are increasing in Thailand with more prevalent in southern Thailand. In this study, our aim is to examine how seasons and water container types affect Culex spp. larvae numbers in Lansaka district, Nakhon Si Thammarat province, southern Thailand. This study was conducted in five sub-districts (Lansaka, Khaokaew, Thadi, Kamlon, and Khunthale) in Lansaka district. In each subdistrict, 120 houses were randomly selected to study the breeding sites of Culex mosquito in dry (March-May, 2018) and wet (October-December, 2018) seasons. Mosquito larvae were collected from indoor, outdoor, natural, artificial, darkcoloured, light-coloured, with lid, and without lid containers. It was observed that in all sub-districts, Culex larvae numbers were higher in dry season compared to wet season. In both seasons, outdoor, without lid, dark-coloured, and artificial containers contained more Culex larvae than inside, with lid, light-coloured, and natural containers, respectively. This study shows that seasons and water container types affect Culex mosquito larvae. Since the larvae numbers are higher in dry season, as well as in outdoor, without lid, dark-coloured, and artificial containers, people should reduce the usage of these containers, especially in the dry season, to prevent Culex borne diseases.

Time allocations for different activities in the fiddler crab Tubuca rosea(Tweedie, 1937) (Brachyura, Ocypodidae)ˆien

Investigating the time activity budgets of fiddler crabs is very important to determine the effects of sex and body size on allocating time for different activities. Few previous studies investigated the effects of sex and body size on time allocations in underground mating species. This study determines the effects of sex, size and their interaction on time allocations in a surface mating species (Tubuca rosea (Tweedie, 1937)). The surface activities of large and small, male and female crabs were video recorded. Afterwards time allocations for various activities (e.g., feeding, standing (vigilance), walking, inside burrows, grooming, burrowing, mating, and for males only, fighting and claw-waving) were calculated. All crabs spent most of their time on feeding than on other activities. Smaller crabs spent more time being vigilant, whereas larger crabs spent more time on courtship displays (grooming, and waving), and fighting. Between sexes, females spent more time standing, but less time on walking and grooming than males. Predation risk, reproductive maturation, breeding/non-breeding season, and energy conservation could be important factors for shaping time allocations in T. rosea.(AU)

Time allocations for different activities in the fiddler crab Tubuca rosea(Tweedie, 1937) (Brachyura, Ocypodidae)ˆien

Investigating the time activity budgets of fiddler crabs is very important to determine the effects of sex and body size on allocating time for different activities. Few previous studies investigated the effects of sex and body size on time allocations in underground mating species. This study determines the effects of sex, size and their interaction on time allocations in a surface mating species (Tubuca rosea (Tweedie, 1937)). The surface activities of large and small, male and female crabs were video recorded. Afterwards time allocations for various activities (e.g., feeding, standing (vigilance), walking, inside burrows, grooming, burrowing, mating, and for males only, fighting and claw-waving) were calculated. All crabs spent most of their time on feeding than on other activities. Smaller crabs spent more time being vigilant, whereas larger crabs spent more time on courtship displays (grooming, and waving), and fighting. Between sexes, females spent more time standing, but less time on walking and grooming than males. Predation risk, reproductive maturation, breeding/non-breeding season, and energy conservation could be important factors for shaping time allocations in T. rosea.