Tadpole assemblages in freshwater wetlands in Hong Kong and anti-predator responses in anuran tadpoles.

Jazyk: Chinese<br />English
Rok vydání: 2012
Předmět:
Druh dokumentu: Bibliografie
Popis: Environmental characteristics, larval amphibian assemblages and associated predators in twelve freshwater wetlands in Hong Kong were investigated from June 2009 to June 2010, in order to identify the key environmental characteristic(s) affecting the richness and abundance of tadpoles in freshwater wetlands in Hong Kong. Predator induced changes in morphology and behavior of three tadpole species (Fejervarya limnocharis, Polypedates megacephalus and Rana guentheri) were examined under the presence of Paradise Fish (Macropodus opercularis), Mosquito Fish (Gambusia affinis), Cybister and dragonfly naiads (Aeshnid) in order to investigate predator inducible defense(s) in local tadpoles and its relation to tadpoles’ distribution and effectiveness of local predators.
Fauna assemblages in 12 freshwater wetlands included 11 amphibian, 16 fish, 31 odonate (24 Anisoptera and 7 Zygoptera), four coleopteran and three hemipteran species. R. guentheri was the most widespread species and occupied both permanent and temporary wetlands. P. megacephalus were most commonly found in temporary wetlands without predators and F. limnocharis were common in wetlands with longer hydroperiod but without predators. Mosquito fish and Orthetrum sabina sabina were the most abundant and widespread fish and dragonfly species, respectively.
Abundance and occurrence of individual tadpole species were more attributable to environmental characteristics than to predators. Wetland hydroperiod was the most influential factor that correlated with environmental characteristics and occurrence of predator species. Larval amphibian richness was highest in temporary wetlands while dragonfly richness increased with habitat permanence. Other environmental characteristics such as substrate types, water depth and vegetation coverage also affected abundance of individual amphibian species.
Three tadpole species were capable of recognizing predators and exhibiting differential inducible changes when exposed to invertebrate and fish predators. P. megacephalus exhibited a large and prominent white spot at the body-tail intersection in the presence of invertebrate predators, and exhibited a growth cost in maintaining an enlarged tail. Tail coloration changed in P. megacephalus and R. guentheri in the presence of predators. Burst swimming performance was associated with body shape in P. megacephalus and to body size in R. guentheri and F. limnocharis. All three tadpole species showed a reduction in active time, travel distance and swimming speed in the presence of predators. R. guentheri reduced activity level for a longer time period after sensing invertebrate predation cues than after sensing fish cues. The variations in plasticity of predator-induced traits increased with predator encounter rate.
Fish caused a greater impact on tadpole abundance than dragonflies in field study, while coleopterans and hemipterans were probably not the major predators of tadpoles as no negative correlation with tadpoles were found. Efficiency of predation varied among fish species. The Paradise Fish was an efficient predator of tadpoles. Mosquito fish consumed fewer tadpoles and yet could cause a significant decline in tadpole populations by its foraging behavior and abundance in local freshwater wetlands. Dragonflies were efficient predator of tadpoles, however, the predation risk to tadpoles could be alleviated by synchronized timing of naiad emergence and amphibian breeding, along with predator-induced defenses of the tadpoles.
Detailed summary in vernacular field only.
Wong, Chuk Kwan.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2012.
Includes bibliographical references (leaves 199-215).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
also in Chinese.
p.i
Acknowledgements --- p.vii
of Contents --- p.ix
List of Tables --- p.xii
List of Figures --- p.xv
List of Plates --- p.xvii
Chapter Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- Wetlands --- p.1
Chapter 1.1.1 --- Definition --- p.1
Chapter 1.1.2 --- Wetland functions --- p.2
Chapter 1.1.3 --- Hydrology and hydroperiod --- p.3
Chapter 1.1.4 --- Predation and inducible defenses --- p.5
Chapter 1.1.5 --- Predictions on inducible defenses --- p.7
Chapter 1.2 --- Hong Kong Situations --- p.9
Chapter 1.2.1 --- Climates in Hong Kong --- p.9
Chapter 1.2.2 --- Amphibians diversity and habitats --- p.11
Chapter 1.2.3 --- Habitat loss in Hong Kong and neighboring regions --- p.12
Chapter 1.2.4 --- Wetland conservation policy in Hong Kong --- p.14
Chapter 1.3 --- Knowledge Gap and Significance --- p.17
Chapter 1.4 --- Objectives --- p.19
Chapter 1.5 --- Thesis Layout --- p.19
Chapter Chapter 2 --- Assemblages of larval amphibians and associated predators in freshwater wetlands in Hong Kong --- p.21
Chapter 2.1 --- Introduction --- p.21
Chapter 2.2 --- Materials and Methods --- p.24
Chapter 2.2.1 --- Study sites --- p.24
Chapter 2.2.1.1 --- Fauna survey --- p.24
Chapter 2.2.1.2 --- Hydroperiod estimation --- p.29
Chapter 2.2.1.3 --- Environmental characteristics --- p.31
Chapter 2.2.1.4 --- Water quality --- p.31
Chapter 2.2.2 --- Data analysis --- p.33
Chapter 2.2.2.1 --- Multivariate analysis --- p.33
Chapter 2.2.2.2 --- Data transformation --- p.34
Chapter 2.3 --- Results --- p.39
Chapter 2.3.1 --- Site characteristics --- p.39
Chapter 2.3.1.1 --- Environmental characteristics --- p.39
Chapter 2.3.1.2 --- Seasonal variation in water quality and wetness score --- p.43
Chapter 2.3.1.3 --- Seasonal variation in water quality in four wetland types --- p.46
Chapter 2.3.2 --- Species assemblages in local wetlands --- p.47
Chapter 2.3.2.1 --- Tadpoles --- p.48
Chapter 2.3.2.2 --- Dragonflies --- p.53
Chapter 2.3.2.3 --- Damselflies --- p.53
Chapter 2.3.2.4 --- Freshwater fish --- p.54
Chapter 2.3.2.5 --- Coleopterans and hemipterans --- p.54
Chapter 2.3.2.6 --- Seasonal variations in species assemblages --- p.55
Chapter 2.3.3 --- Biodiversity of study sites --- p.58
Chapter 2.3.3.1 --- Species richness in study sites --- p.58
Chapter 2.3.3.2 --- Species abundance in study sites --- p.63
Chapter 2.3.4 --- Multivariate analysis --- p.64
Chapter 2.3.4.1 --- Global approach --- p.64
Chapter 2.3.4.2 --- Independent approach --- p.76
Chapter 2.3.4.3 --- Predator approach --- p.81
Chapter 2.3.5 --- Hydroperiod and faunal assemblages --- p.92
Chapter 2.3.5.1 --- Effect of hydroperiod on wetland diversity --- p.92
Chapter 2.3.5.2 --- Effects of hydroperiod on faunal groups --- p.94
Chapter 2.3.5.3 --- Effects of hydroperiod on species composition --- p.96
Chapter 2.3.5.4 --- Comparison with other explanatory variables --- p.98
Chapter 2.3.6 --- Hydroperiod, environmental characteristics and predation --- p.98
Chapter 2.3.6.1 --- Effects of hydroperiod on environmental characteristics --- p.98
Chapter 2.3.6.2 --- Effects of environmental characteristics on tadpoles --- p.99
Chapter 2.3.6.3 --- Effects of predation on tadpoles --- p.99
Chapter 2.3.6.4 --- Relative importance of environmental characteristics and predation --- p.100
Chapter 2.3.7 --- Tadpole traits, wetland permanence and predation pressure --- p.100
Chapter 2.4 --- Discussion --- p.104
Chapter 2.5 --- Conclusions --- p.112
Chapter Chapter 3 --- Predator-induced plasticity in tadpoles and its effect on survivorship under the presence of different groups of predator --- p.113
Chapter 3.1 --- Introduction --- p.113
Chapter 3.2 --- Materials and Methods --- p.117
Chapter 3.2.1 --- Egg collection --- p.117
Chapter 3.2.1 --- Predator collection --- p.118
Chapter 3.2.2 --- Experimental design --- p.119
Chapter 3.2.2.1 --- Predator induced plasticity in tadpoles --- p.119
Chapter 3.2.2.2 --- Predation experiment --- p.126
Chapter 3.2.3 --- Data analysis --- p.128
Chapter 3.3 --- Results --- p.130
Chapter 3.3.1 --- Morphological responses --- p.131
Chapter 3.3.2 --- Tail coloration --- p.135
Chapter 3.3.3 --- Burst swimming performance --- p.144
Chapter 3.3.4 --- Life history --- p.149
Chapter 3.3.5 --- Activity test --- p.153
Chapter 3.3.5.1 --- Predator effects on activity level of Paddy Frog tadpoles --- p.153
Chapter 3.3.5.2 --- Predator effects on activity level of Brown Tree Frog tadpoles --- p.157
Chapter 3.3.5.3 --- Predator effects on activity level of Guenther’s Frog tadpoles --- p.160
Chapter 3.3.6 --- Predation experiment --- p.164
Chapter 3.4 --- Discussion --- p.174
Chapter 3.4.1 --- Inducible changes in Paddy Frog tadpoles --- p.174
Chapter 3.4.2 --- Inducible changes in Brown Tree Frog tadpoles --- p.175
Chapter 3.4.3 --- Inducible response to rarely encountered fish --- p.178
Chapter 3.4.4 --- Inducible changes in Guenther’s Frog tadpoles --- p.179
Chapter 3.4.5 --- Effect of inducible defenses on tadpole survival --- p.180
Chapter 3.4.6 --- Predator inducible changes and hydroperiod gradient --- p.181
Chapter 3.4.7 --- Predator strength --- p.183
Chapter 3.4.8 --- Importance of predation on tadpole assemblages --- p.185
Chapter 3.5 --- Conclusions --- p.186
Chapter Chapter 4 --- General Conclusions --- p.187
Chapter 4.1 --- Summary --- p.187
Chapter 4.2 --- Applications --- p.189
Chapter 4.2.1 --- Mitigation wetlands --- p.189
Chapter 4.2.1.1 --- Design --- p.189
Chapter 4.2.1.2 --- Placement --- p.192
Chapter 4.2.1.3 --- Management practices --- p.192
Chapter 4.2.1.4 --- Natural model of temporary wetland --- p.194
Chapter 4.2.2 --- Wetland conservation --- p.195
Chapter 4.3 --- Further studies --- p.197
References --- p.199
Appendices --- p.216
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