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.

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.”

Red Crabs in Rain Forest, Christmas Island: Differential Herbivory of Seedlings

Oikos ◽  
1990 ◽  
Vol 58 (3) ◽  
pp. 289 ◽  
Author(s):  
Dennis J. O'Dowd ◽  
P. S. Lake
Keyword(s):  
Rain Forest ◽  
Christmas Island

scholarly journals Rainfall as a significant contributing factor to butterfly seasonality along a climatic gradient in the neotropics

2019 ◽  
Author(s):  
María F. Checa ◽  
Elisa Levy ◽  
Jaqueline Rodriguez ◽  
Keith Willmott
Keyword(s):  
Temporal Dynamics ◽  
Dry Forest ◽  
Butterfly Species ◽  
Climatic Gradient ◽  
Wet Season ◽  
Precipitation Regimes ◽  
Butterfly Communities ◽  
Set Up ◽  
Study Sites ◽  
Seasonal Forests

AbstractWe analyzed the dynamics of multi-species butterfly communities along a climatic gradient with varying precipitation regimes for three consecutive years, and determine how climatic variables associate with observed butterfly seasonality. To provide a baseline for future studies of how climate change might affect these butterfly populations, we additionally explored the role of butterfly seasonality as a potential contributing factor for their susceptibility to climate variation. As far as we know, this represents the first study that simultaneously sampled and described seasonality patterns of tropical butterfly communities across ecosystems with varying climatic seasonality. A 3-year survey was carried out at three sites (i.e., wet, transition and dry forests) across a climatic gradient in western Ecuador. Butterflies were sampled using traps baited with rotting banana and prawn every two months from Nov 2010 to Sep 2013. Traps were set up at two heights, in the understory and canopy. In total, 7046 individuals of 212 species were sampled over 180 sampling days.Butterfly communities exhibited conspicuous intra and inter-annual variation in temporal dynamics with certain elements (e.g., maximum abundance recorded) of seasonality patterns likely synchronized in seasonal forests (i.e., transition and dry forest) across years but not in aseasonal forests (i.e., wet forest). In addition, the highest numbers of species and individuals occurred during the wet season across all study sites and years; indeed, rainfall was significantly positively associated with temporal abundance. Likewise, butterfly species displaying stronger seasonality were significantly associated with higher rainfall periods in seasonal forests. Variation in precipitation regimes might significantly affect more seasonal species.

scholarly journals KEPADATAN STOK IKAN DEMERSAL DAN UDANG DI SAMUDERA HINDIA BARAT SUMATERA PADA MUSIM PERALIHAN II

2017 ◽  
Vol 22 (3) ◽  
pp. 139
Author(s):  
Nurulludin Nurulludin ◽  
Thomas Hidayat ◽  
Asep Mamun
Keyword(s):  
Indian Ocean ◽  
Demersal Fish ◽  
Catch Rate ◽  
Fish Stock ◽  
Fish Resources ◽  
The Indian Ocean ◽  
Density And Biomass ◽  
Swept Area ◽  
Average Catch ◽  
Stock Abundance

Kepadatan stok ikan merupakan indikasi dari potensi perikanan di suatu wilayah yang sangat penting diketahui. Tujuan tulisan ini membahas tentang laju tangkap, kepadatan stok dan perkiraan biomassa ikan demersal serta udang. Penelitian sumber daya ikan demersal dan udang di Samudera Hindia Barat Sumatera dilakukan dengan menggunakan Kapal Riset Baruna Jaya IV (1.200 GT) pada bulan Oktober dan November 2015 (Musim peralihan II). Penghitungan kepadatan stok menggunakan metode sweept area dengan panjang tali ris atas dari jaring trawl 36 m, kecepatan kapal saat menarik jaring berkisar 2,5 – 3 knot, lama penarikan jaring maksimal 1 jam. Perairan Samudera Hindia Barat Sumatera terdiri dari 151 spesies yang tergolong dalam 59 famili. Famili ikan demersal yang dominan tertangkap (5 besar), yaitu Leiognathidae sebesar 23,6 %, Trichiuridae 9,8%, Haemulidae 8,0%,  Engraulididae 6,6%, dan Polynemidae 6,05%. Famili udang yaitu Penaeidae (79,08%), Scyllaridae 19,49%, dan Solenoceridae 1,43%. Rata-rata laju tangkap ikan demersal 205,80 kg/jam, dengan kepadatan stok 6,66 ton/km2 dan udang 2,30 kg/jam dengan kepadatan stok 0,053 ton/km2. Biomassa ikan demersal diperkirakan sebesar 470.122 ton dan udang 3.706 ton.  Fish stock density  is an index of stock abundance indicating the fish resources potential in a region.  This paper discusses the catch rate, stock density and biomass estimates of the demersal fish and shrimp resources. Research on the demersal fish and shrimp resources in the Indian Ocean-Western Sumatera conducted using the Research Vessel Baruna Jaya IV (1200 GT) carried out during  October and November 2015 (2nd intermonsoon season). Stock density was estimated through the swept area method. The trawl used has 36 m headrope, trawling speed of 2.5 - 3 knots, and maximum towing time was 1 hour. It was found that the fish resources in the waters of the Indian Ocean-Western Sumatera consisted of 151 species belonging to 59 families. The top five dominant fish families caught were Leiognathidae of 23.6%, Trichiuridae 9.8%, Haemulidae 8.0%, Engraulididae 6.6%, and Polynemidae 6.05%, while the shrimp families were Penaeidae of 79.08%, Scyllaridae 19.49%, and Solenoceridae 1.43%. The average catch rate of demersal fish was 205.80 kg/hour, with a stock density of 6.66 tons/km2 and shrimp of 2.30 kg/hour with a stock density of 5.3 kgs/km2. The estimated biomass of demersal fish was  470,122 tons and shrimp was 3,706 tons.  

scholarly journals The Morphological Measurement Variations of Periophthalmus chrysospilos along the Coastline in the Mekong Delta

2021 ◽  
Author(s):  
Le Trung Hieu ◽  
Dinh Minh Quang ◽  
Hua Van U ◽  
Nguyen Huu Duc Ton
Keyword(s):  
Morphological Variation ◽  
Body Height ◽  
Mekong Delta ◽  
Wet Season ◽  
Morphological Variations ◽  
Total Length ◽  
Fish Samples ◽  
Eye Diameter ◽  
And Gender ◽  
Study Sites

This study provided data on morphological variation in Periophthalmus chrysospilos. The study was carried out in four provinces from Tra Vinh to Soc Trang, Bac Lieu and Ca Mau. Fish samples were collected by hand-catching over 12 months from April 2020 to March 2021. Analysed results of a collection of 1,031 individuals (508 females and 523 males) showed that the total length (TL) and weight (W) of the female Periophthalmus chrysospilos were higher than that of the male, higher in the wet season than in the dry season and gradually increased from Tra Vinh to Ca Mau. Besides, the total length and weight of fish were also influenced by the interaction of season ´ site and gender ´ site. In addition, the morphological variation of this species such as eye diameter (ED), eye distance (DE), body height (BD), head length (HL) and taxonomic ratios such as HL/TL, BD/TL, ED/HL, DE/HL was gender, seasonal fluctuations and study sites. These morphological variations and ratios were also influenced by interactions season ´ site interactions. The findings contributed further information to fish identification and the ecological adaptation understanding of this species.

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