The Breeding Behaviour and Migrations of the Terrestrial Crab Gecarcoidea natalis (Decapoda: Brachyura)

1985 ◽  
Vol 33 (2) ◽  
pp. 127 ◽  
Author(s):  
JW Hicks
Keyword(s):  
Salt Water ◽  
High Tide ◽  
Wet Season ◽  
Mating Activity ◽  
Migration Activity ◽  
Christmas Island ◽  
Large Numbers ◽  
Hard Shell ◽  
Gecarcoidea Natalis ◽  
Crab Stage

The breeding migrations of the Christmas Island red crab were monitored at plateau and shoreline locations from November 1979 to May 1983. Up to three migration sequences, each resulting in egg release, occurred each year in a breeding season lasting up to 3 months. In the main sequence migration from the plateau to the shore began at the onset of the wet season and lasted 9-18 days. On arrival at the sea, crabs immersed in salt water in large numbers before retreating to the shore terrace rainforest, where males fought over possession of burrows. Crabs courted and copulated near or in the burrows; they copulated in a hard-shell condition with the male generally underneath. At the conclusion of mating activity, males again dipped in salt water before returning to the plateau. Females remained in burrows on the shore terrace for 12-13 days until eggs were nearly ripe; they then moved to shoreline rocks. They released their eggs at night on the turn of the high tide between the last quarter of the moon and the new moon, sometimes from cliff faces, then returned en masse to the plateau. Zoeae hatched immediately on contact with salt water, and baby crabs emerged at the first crab stage 27 days after egg release; successful emergence varied considerably between seasons. Baby crabs migrated inland, taking 9 days to reach the plateau. Most migration activity was diurnal, the main exceptions were egg release and dipping activities.

scholarly journals An update on the distribution of Glossina (tsetse flies) at the wildlife-human-livestock interface of Akagera National Park, Rwanda

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Richard S. Gashururu ◽  
Samuel M. Githigia ◽  
Methode N. Gasana ◽  
Richard Habimana ◽  
Ndichu Maingi ◽  
...  
Keyword(s):  
National Park ◽  
Control Strategies ◽  
Glossina Pallidipes ◽  
Distribution Patterns ◽  
Tsetse Flies ◽  
Wet Season ◽  
Chi Square ◽  
Large Numbers ◽  
Surrounding Areas ◽  
Biconical Traps

Abstract Background Glossina (tsetse flies) biologically transmit trypanosomes that infect both humans and animals. Knowledge of their distribution patterns is a key element to better understand the transmission dynamics of trypanosomosis. Tsetse distribution in Rwanda has not been well enough documented, and little is known on their current distribution. This study determined the current spatial distribution, abundance, diversity, and seasonal variations of tsetse flies in and around the Akagera National Park. Methods A longitudinal stratified sampling following the seasons was used. Biconical traps were deployed in 55 sites for 6 consecutive days of each study month from May 2018 to June 2019 and emptied every 48 h. Flies were identified using FAO keys, and the number of flies per trap day (FTD) was used to determine the apparent density. Pearson chi-square (χ2) and parametrical tests (t-test and ANOVA) were used to determine the variations between the variables. The significance (p < 0.05) at 95% confidence interval was considered. Logistic regression was used to determine the association between tsetse occurrence and the associated predictors. Results A total of 39,516 tsetse flies were collected, of which 73.4 and 26.6% were from inside Akagera NP and the interface area, respectively. Female flies accounted for 61.3 while 38.7% were males. Two species were identified, i.e. G. pallidipes [n = 29,121, 7.4 flies/trap/day (FTD)] and G. morsitans centralis (n = 10,395; 2.6 FTD). The statistical difference in numbers was significant between the two species (p = 0.000). The flies were more abundant during the wet season (15.8 FTD) than the dry season (4.2 FTD). Large numbers of flies were trapped around the swamp areas (69.1 FTD) inside the park and in Nyagatare District (11.2 FTD) at the interface. Glossina morsitans was 0.218 times less likely to occur outside the park. The chance of co-existing between the two species reduced outside the protected area (0.021 times). Conclusions The occurrence of Glossina seems to be limited to the protected Akagera NP and a narrow band of its surrounding areas. This finding will be crucial to design appropriate control strategies. Glossina pallidipes was found in higher numbers and therefore is conceivably the most important vector of trypanosomosis. Regional coordinated control and regular monitoring of Glossina distribution are recommended. Graphic Abstract

Lampetra macrostoma, a New Species of Freshwater Parasitic Lamprey from the West Coast of Canada

1982 ◽  
Vol 39 (5) ◽  
pp. 736-747 ◽  
Author(s):  
Richard J. Beamish
Keyword(s):  
British Columbia ◽  
New Species ◽  
West Coast ◽  
Related Species ◽  
Salt Water ◽  
Vancouver Island ◽  
The West ◽  
Large Disc ◽  
Large Numbers ◽  
A New Species

Lampetra macrostoma n.sp., a freshwater parasitic lamprey, is distinguished from related species L. tridentata, L. lethophaga, L. folletti, L. minima, and L. similis by its parasitic habit and very large disc. Other characters distinguishing the species from L. tridentata are its longer prebranchial length, large eye, weakly pigmented velar tentacles, and its ability to remain in freshwater. The recently metamorphosed form readily survives in freshwater and probably is non-anadromous even though it can survive in salt water. The new species has been discovered in two lakes on Vancouver Island, British Columbia, Canada, where it attacks large numbers of resident salmonids. Because of its ability to survive and feed in freshwater, it poses a definite threat to freshwater fishes.Key words: lamprey, new species, non-anadromous lamprey, salmonid parasitism

EXERCISE IN THE TERRESTRIAL CHRISTMAS ISLAND RED CRAB GECARCOIDEA NATALIS - BLOOD GAS TRANSPORT

1994 ◽  
Vol 188 (1) ◽  
pp. 235-256 ◽  
Author(s):  
A Adamczewska ◽  
S Morris
Keyword(s):  
Gas Transport ◽  
Lactate Production ◽  
Circulatory System ◽  
Indirect Evidence ◽  
Blood Gas ◽  
Christmas Island ◽  
Exercise Period ◽  
Gas Measurements ◽  
Gecarcoidea Natalis ◽  
O2 Delivery

The respiratory and circulatory physiology of the terrestrial Christmas Island red crab Gecarcoidea natalis was investigated with respect to exercise in the context of its annual breeding migration. Red crabs were allowed to walk for predetermined periods of up to 45 min. During this exercise period, blood gas measurements were made on venous, pulmonary and arterial samples to assess the function of the lungs in gas exchange and the performance of the circulatory system in gas transport and to determine the role and importance of the haemocyanin. The lungs of G. natalis were very efficient at O2 uptake, pulmonary blood being 80&shy;90 % saturated throughout the 45 min exercise period. The maximum O2-carrying capacity was 1.1 mmol l-1, and haemocyanin (Hc) delivered 86 % of oxygen in resting crabs and 97 % during exercise. Oxygen delivery to the tissues was diffusion-limited during exercise. Indirect evidence, from the changes in haemolymph pH during transit through the lungs, suggested that the lung is the site of CO2 excretion. The Bohr shift was high at high pH (pH 7.8&shy;7.5, phi=-1.23) but decreased at low pH (pH 7.1&shy;6.8, phi=-0.48). The decreased Hc affinity for O2 during the exercise period facilitated O2 delivery to the tissues without impairing O2 loading at the lungs. The decrease in pH was sufficient to explain the change of affinity of Hc for O2 during the exercise period. The marked acidosis (0.8 pH unit decrease) was largely metabolic in origin, especially during sustained locomotion, but less than could be predicted from concomitant lactate production.

limited data for the greater Townsville area (Kay et al.1996). Based on the prevalence of key vector species and their abundance and that of the viruses recovered, it was concluded that Big Bay, originally recommended as a prime site for recreational development by the Department of Local Government in 1985, actually presented lower risk than any other locality. Antill Creek also proved relatively safe in terms of mosquito-borne infections, whereas Toonpan during the wet season was a place to be avoided. Both Ross River and the environs of Townsville offered intermediate risk, the latter due to large numbers of saltmarsh mosquitoes breeding in intertidal wetlands. 9.5 Snails and swimmer’s itch Schistosome dermatitis, known as swimmer’s itch, is a common global problem for users of recreational swimming areas in water resource developments. The rash is caused by free living larvae called cercariae (Figure 9.4) of parasitic flukes which burrow into exposed parts of the body. Normally the life-cycle involves water birds such as ducks and pulmonate snails, so infection of humans is accidental. A large number of cercariae may penetrate the skin where they die but cause a localized allergic reaction in sensitized persons. In northern Australia, swimmer’s itch (Trichobilharzia) has been traditionally associated with Austropeplea (= Lymnaea) lessoni (= vinosa) although two planorbid snails, Amerianna carinata and Gyraulus stabilis, have also been identified as intermediate hosts in Lake Moondarra near Mt Isa, Queensland. Our recent data implicates Gyraulus gilberti at the Ross River dam. Snails are also commonly infected with other trematode cercariae, mainly echinostomes, strigeids/diplostomids and clinostomids.

1998 ◽  
pp. 148-148
Keyword(s):  
Lower Risk ◽  
The Body ◽  
Northern Australia ◽  
Intermediate Hosts ◽  
Wet Season ◽  
Large Numbers ◽  
Swimmer’S Itch ◽  
Intertidal Wetlands ◽  
Water Birds ◽  
Swimmer's Itch

The relation between mating activity of rams in pens and subsequent flock mating performance

1980 ◽  
Vol 20 (102) ◽  
pp. 5 ◽  
Author(s):  
RJ Kilgour ◽  
RG Whale
Keyword(s):  
Mating Test ◽  
Mating Activity ◽  
Large Numbers ◽  
Mating Tests ◽  
Mating Performance

The serving activity of seven rams in one 20-minute pen mating test followed by two one-hour pen mating tests was recorded. The mating performance of each ram during a single-sire flock mating was subsequently monitored. Mean number of services in the two one-hour pen tests gave the best prediction of the number of ewes inseminated during flock mating (r = 0.88, P < 0.01). The number of services in the 20-minute test gave a poor prediction of the number of ewes inseminated (r = 0.30). The total number of services during the first 20-minutes of the two one-hour tests (2x20-minute tally), the number of services during the 20-minute test and the first 20 minutes of the first one-hour test (2 x 20-minute tally) and the number of services during the 20-minute test and the first 20 minutes of the two one-hour tests (3x20-minute tally) were only moderately correlated with number of ewes inseminated (r = 0.67, r = 0.47 and r = 0.64, respectively). These results explain why other workers, using combinations of 20-minute tests, have failed to demonstrate a relationship between pen mating tests and flock fertility. The results further show that a measure of the serving activity of rams in pens can be used to identify rams that are capable of mating large numbers of ewes, and that the development of a commercially applicable test is worthwhile.

scholarly journals Computer analysis of benthic foraminiferal associations in a tidal New Zealand inlet

1994 ◽  
Vol 13 (2) ◽  
pp. 103-117 ◽  
Author(s):  
Bruce W. Hayward ◽  
Christopher M. Triggs
Keyword(s):  
New Zealand ◽  
Correspondence Analysis ◽  
Salt Water ◽  
High Tide ◽  
Fine Sand ◽  
Muddy Sand ◽  
Small Stream ◽  
Shallow Subtidal ◽  
Faunal Distribution ◽  
Normal Salinity

Abstract. Census data on benthic foraminiferal tests in 45 surface sediment samples from Pauatahanui Inlet, Wellington, New Zealand, are analysed by Correspondence Analysis and Non-Hierarchical classification techniques. The faunas are grouped into 7 associations: (A) Trochamminita irregularis/Miliammina fusca - at high tide level in a small tidal creek at the limits of salt water influence; (B) Trochammina inflata/Jadammina macrescens - in an extreme high tidal pool, close to the mouth of a small stream; (C) Miliammina fusca/Haplophragmoides wilberti/Trochammina inflata - intertidal and shallow subtidal (to 0.6 m depth), muddy sand over a large area in the upper reaches of the inlet, where most freshwater runoff enters; (D) Elphidium excavatum/Miliammina fusca - intertidal muddy sand associated with shelly beaches on the fringe of association C; (E) Ammonia beccarii/Haynesina depressula - in a wide variety of intertidal and shallow subtidal (to 3 m depth) sediments that form a belt between the more brackish associations (A–D) and the more normal salinity associations (F–G); (F) Bolivina cf. translucens/Textularia earlandi/Bolivina subexcavata - in mud to muddy, very fine sand in a shallow basin (1–2.5 m deep) in the middle of the inlet and in a small, sheltered backwater; (G) Elphidium charlottensis/Patellinella inconspicua/Quinqueloculina seminula - in sandy mud and muddy fine sand, intertidal to 10 m depth, in the mouth, entrance channel and adjacent outer and middle parts of the inlet, where a flush of normal salinity water enters during each tidal cycle.Using Canonical Correspondence Analysis, the factors most influential in determining the faunal distribution are, in decreasing importance: freshwater influence (salinity), exposure to the air during tidal cycles, proximity to the open sea, tidal current strength and percentage of mud in the substrate.

STUDIES OF WATERFOWL IN BRITISH COLUMBIA: GREATER SCAUP DUCK, LESSER SCAUP DUCK

1941 ◽  
Vol 19d (4) ◽  
pp. 113-138 ◽  
Author(s):  
J. A. Munro
Keyword(s):  
British Columbia ◽  
Sex Ratio ◽  
Salt Water ◽  
Age Groups ◽  
Economic Significance ◽  
Lesser Scaup ◽  
Large Numbers ◽  
Salmon Eggs ◽  
Winter Flocks ◽  
Coast Region

Nyroca marila is an abundant migrant through British Columbia and large numbers winter in the coast region. The sex ratio in winter flocks is predominantly male. Chara was the chief food eaten by 57 specimens from Okanagan Lake, miscellaneous vegetable matter was second, and molluscs third in importance. Food items, listed in order of importance, on coast streams and lakes were: vegetable matter, molluscs, salmon eggs, salmon flesh, and, on salt water: gastropods, sea lettuce (Ulva sp.), crustaceans, and herring eggs. N. affinis nests commonly in parts of the dry interior and elsewhere in the province is a migrant and scarce winter visitant. Sex ratio is predominantly male. Courtship continues through April and May; laying commences in June and late clutches are found in August. Females defend their young vigorously and a habit of combining broods has a probable survival value. Males raft on certain lakes in July and go into eclipse as flight feathers are shed. These populations include yearling and post-breeding females and later, adolescents. The former moult at this time. Adults migrate early and those remaining are largely young of the year. Amphipods are the chief food of all age groups on the nesting ground; aquatic insects and seeds of aquatic plants are also important. Both species of scaup ducks are economically important as food and for sport in the interior but less so on the coast where, because of a different diet, their flesh is less palatable. It was not determined whether the consumption of salmon eggs and herring eggs is of economic significance. Elsewhere than on the coast scaup ducks are related to other interests only to the limited extent to which they are food competitors of trout and other commercially valuable fishes.

scholarly journals Temporal Variations of Submarine Groundwater Discharge into a Tide-Dominated Coastal Wetland (Gaomei Wetland, Western Taiwan) Indicated by Radon and Radium Isotopes

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1806 ◽  
Author(s):  
Feng-Hsin Hsu ◽  
Chih-Chieh Su ◽  
Pei-Ling Wang ◽  
In-Tian Lin
Keyword(s):  
Coastal Waters ◽  
Seasonal Changes ◽  
Submarine Groundwater Discharge ◽  
Coastal Wetland ◽  
Groundwater Discharge ◽  
High Tide ◽  
Dry Season ◽  
Wet Season ◽  
Submarine Groundwater ◽  
Δd And Δ18o

Submarine groundwater discharge (SGD) is evidenced around Taiwan, but the seasonal/temporal changes of SGD have not been fully examined. Here, we report a time-series investigation of SGD into a tide-dominated coastal wetland, the Gaomei Wetland, located to the south of the Da-Chia River’s mouth, western Taiwan, by using environmental tracers (222Rn, 224Raex, 228Ra, δD, and δ18O). Our results showed that regardless of dry and wet seasons, the 222Rn activities in coastal waters were high at low tide but low at high tide. It represents the continuous input of 222Rn-enriched groundwater. However, the 224Raex and 228Ra activities showed seasonal changes with tide conditions. In the dry season, the 224Raex and 228Ra activities in coastal waters were low at low tide but high at high tide; whereas in the wet season, an opposite relation was observed with quite high 224Raex and 228Ra activities in the low-tide waters. Coupled with the lower δD and δ18O values of coastal and pore waters in the dry season, in comparison to those in the wet season, it is suggested that these phenomena probably reflected a seasonal difference in the main SGD component with fresh SGD in the dry season, but saline ones in the wet season. Based on a 222Rn mass balance model, the estimated SGD fluxes into the Gaomei Wetland varied with tidal fluctuations and ranged from 0.2 to 25 cm d−1 and from 0.1 to 47 cm d−1 for the dry and wet seasons, respectively. A slightly high SGD flux occurring during the wet season at spring tide, implied a stronger tidal pumping coupled with a larger hydraulic gradient between land and sea. In this study, we demonstrated that the variation of SGD into the Gaomei Wetland is not only controlled by the seasonal changes of groundwater recharge, but also by the tidal pumping process.

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