scholarly journals Burrow Dynamics of the Red Land Crab Gecarcoidea Natalis (Brachyura, Gecarcinidae) in Rain Forest on Christmas Island (Indian Ocean)

2004 ◽  
Vol 24 (2) ◽  
pp. 340-349 ◽  
Author(s):  
Peter T. Green
Keyword(s):  
Indian Ocean ◽  
Rain Forest ◽  
Land Crab ◽  
Christmas Island ◽  
Gecarcoidea Natalis

Red crabs in rain forest, Christmas Island: removal and relocation of leaf-fall

1989 ◽  
Vol 5 (3) ◽  
pp. 337-348 ◽  
Author(s):  
Dennis J. O'Dowd ◽  
P. S. Lake
Keyword(s):  
Rain Forest ◽  
Forest Floor ◽  
Field Experiments ◽  
Single Species ◽  
Leaf Fall ◽  
Land Crab ◽  
Temporal And Spatial Patterns ◽  
Christmas Island ◽  
Temporal And Spatial ◽  
Gecarcoidea Natalis

ABSTRACTField experiments comparing leaf-fall in the presence and absence of the red land crab, Gecarcoidea natalis, in rain forest on Christmas Island, Indian Ocean showed that, by eating and returning leaves to their burrows, they significantly reduced accumulation of leaf-fall on the forest floor. Red crabs removed 30–50% of the leaf-fall at the experimental sites during the study. Differences in leaf-fall mass between crab-access and exclusion quadrats were positively correlated with the density of foraging red crabs. Red crabs also generated spatial heterogeneity in the distribution of litter on the forest floor by returning litter to their burrows. Leaves lined chambers of 64% of excavated burrows and litter biomass around the entrances was significantly greater than that on off-burrow locations. This was reflected in the significantly higher concentrations of organic matter and nutrients (N, P, K, Ca, Na, and Mg) associated with soils near burrow entrances. These results suggest that a single species, G. natalis, is the major processor of leaf-fall in rain forest on Christmas Island and may affect (1) the temporal and spatial patterns of nutrient availability and (2) the diversity and biomass of the litter fauna.

scholarly journals Erratum

1997 ◽  
Vol 13 (4) ◽  
pp. 578-578
Author(s):  
P. Green
Keyword(s):  
Indian Ocean ◽  
Total Variation ◽  
Rain Forest ◽  
Activity Patterns ◽  
Christmas Island ◽  
Density And Biomass

Green, P. T. (1997)Red crabs in rain forest on Christmas Island, Indian Ocean: activity patterns, density and biomass. Vol. 13 Part 1: 17–38. On page 29 the phrase: “but a significant correlation existed across sites (r=0.81, n=44, P<0.001).” should read: “but a significant correlation existed across sites (r=-0.69, n=44, P<0.001).”On page 33 the phrase “but the same correlation accounted for 81% of total variation when all sites were analysed together.” should read: “but the same correlation accounted for 48% of total variation when all sites were analysed together.”

Phylogeography of the Christmas Island blue crab,Discoplax celeste(Decapoda: Gecarcinidae) on Christmas Island, Indian Ocean

2012 ◽  
Vol 93 (3) ◽  
pp. 703-714 ◽  
Author(s):  
Lucy M. Turner ◽  
J. Paul Hallas ◽  
Michael J. Smith ◽  
Stephen Morris
Keyword(s):  
Indian Ocean ◽  
Habitat Destruction ◽  
Conservation Strategies ◽  
Ecosystem Change ◽  
Anthropogenic Factors ◽  
Genetic Structuring ◽  
Land Crab ◽  
Christmas Island ◽  
Number Of Factors ◽  
The Indian Ocean

The land crab,Discoplax celeste(Gecarcinidae) is endemic to Christmas Island in the Indian Ocean. Due to a freshwater-dependant life history, in which the megalopae migrate from the ocean up freshwater streams to their adult terrestrial/freshwater habitat,D. celesteinhabits only a few isolated locations on the island. This restricted distribution is one of a number of factors which has previously highlighted the vulnerability of this species to outside threats. A number of anthropogenic factors including the introduction of multiple invasive species and habitat destruction have led to drastic ecosystem change on Christmas Island. The aim of this study was to investigate whether the restricted geographical distributions ofD. celestepopulations contribute to significant genetic structuring across Christmas Island, with an objective to inform future conservation strategies for this species on Christmas Island. Fragments of the mitochondrial cytochrome oxidase I gene and the control region were sequenced from 95 individuals collected from all five locations on Christmas Island known to be inhabited byD. celeste. Analyses using analysis of molecular variance revealed no evidence of population sub-structuring, indicating that despite any geographical isolation, there is a single population ofD. celesteon Christmas Island. This lack of population differentiation is probably explained by the oceanic dispersal of larvae, rather than terrestrial migration ofD. celeste. Therefore, based on these results, for conservation purposes,D. celesteon Christmas Island can be considered a single management unit.

Red crabs in rain forest, Christmas Island: removal and fate of fruits and seeds

1991 ◽  
Vol 7 (1) ◽  
pp. 113-122 ◽  
Author(s):  
Dennis J. O'Dowd ◽  
P. S. Lake
Keyword(s):  
Seed Predation ◽  
Rain Forest ◽  
Nitrogen Concentration ◽  
Oceanic Islands ◽  
Fruit Removal ◽  
Land Crab ◽  
Christmas Island ◽  
Direct Observations ◽  
Land Crabs ◽  
Seed Coats

ABSTRACTThe red land crab (Gecarcoidea nalalis) is the major collector of fruits and seeds from the rain forest Moor on Christmas Island, Indian Ocean. At three sites, they rapidly removed fruits and seeds of 17 species tested (usually within 12 h after placement) and most were taken to crab burrows. Direct observations of seed predation, and application of estimated chelar forces of red crabs indicated that seeds of many species, especially those with thin seed coats, are likely to be killed through handling. However, removal of some resistant seeds to burrows may be favourable for seedling establishment when canopy gaps occur. Fruit removal rates by crabs were positively related to nitrogen concentration in fruit tissues but negatively correlated with condensed tannins. These observations suggest that seed predation by land crabs may affect the success of colonization and the relative abundance of plants on oceanic islands.

The systematics of land crabs of the genus Gecarcoidea and recognition of a pseudocryptic species, G. humei, from the eastern Indian Ocean (Crustacea : Decapoda : Gecarcinidae)

2017 ◽  
Vol 31 (4) ◽  
pp. 406 ◽  
Author(s):  
Joelle C. Y. Lai ◽  
Hsi-Te Shih ◽  
Peter K. L. Ng
Keyword(s):  
Indian Ocean ◽  
Morphological Characters ◽  
Eastern Indian Ocean ◽  
Valid Species ◽  
West Pacific ◽  
Land Crab ◽  
Christmas Island ◽  
Extant Species ◽  
Land Crabs ◽  
The Family

The gecarcinid genus Gecarcoidea H. Milne Edwards, 1837 is currently represented by two species from the Indo-West Pacific – the widely distributed purple land crab, G. lalandii H. Milne Edwards, 1837, and the red crab endemic to Christmas Island, G. natalis (Pocock, 1889). One species, G. humei (Wood-Mason, 1874), described from the Nicobar Islands, has had a confused taxonomic history, but was treated as a junior synonym of G. lalandii by Türkay (1974) in his revision of the family. In this study, using molecular as well as morphological characters, we show that G. humei is a valid species. Gecarcoidea lalandii and G. humei have distinct non-overlapping distributions throughout much of their range, with G. lalandii occurring in most of South-east Asia and the West Pacific, while G. humei is known only from the eastern Indian Ocean. On Christmas Island, in the eastern Indian Ocean, however, all three species are present. As a result, Christmas Island is the only locality where all extant species of Gecarcoidea are found. The three species can also be separated by differences in live colours and patterns, as well as proportions of the carapace, male abdomen, ambulatory legs and third maxillipeds, and details of the orbits and male first gonopods.

Red crabs in rain forest on Christmas Island, Indian Ocean: activity patterns, density and biomass

1997 ◽  
Vol 13 (1) ◽  
pp. 17-38 ◽  
Author(s):  
Peter T. Green
Keyword(s):  
Indian Ocean ◽  
Surface Activity ◽  
Rain Forest ◽  
Activity Patterns ◽  
Carapace Width ◽  
Main Study ◽  
Wet Season ◽  
Christmas Island ◽  
Study Sites ◽  
Density And Biomass

ABSTRACTThe red crab Gecarcoidea natalis is the most abundant land crab on Christmas Island, Indian Ocean, and is found wherever native rain forest is still intact. The largest crabs grow to > 120 mm carapace width and reach > 500 g in mass. Red crabs are diurnally active, and moisture appears to be the most important factor governing surface activity – activity was nil below 77% RH, relatively low at 87% RH, and high above 95% RH. The crabs retreat to the interior of their burrows during dry periods, but emerge rapidly in response to rain. Because of their dependence on moisture for surface activity, red crabs show greater levels of activity during the wet season. Annual breeding migrations and moulting activity decreased the density of surface-active crabs at the main study sites for several weeks at the start of the wet season, and fruit and leaf fall caused dramatic local increases in the density of active red crabs. Density and biomass at the main study sites averaged 1.3 crabs m-2 and 1454 kg ha-1, respectively, and 1.2 crabs m-2 and 1137 kg ha-1 at a total of five sites across the island. Rough calculations suggest that the island-wide population is at least 100 million individuals. Red crabs are the dominant consumer on the forest floor, and consume seeds, seedlings and leaf litter. Because they are both abundant and widespread, these animals have the potential to be the most important determinant of pattern and process in rain forest on Christmas Island.

Sign in / Sign up

Export Citation Format

Share Document