Arcitalitrus Dorrieni Research Articles

A “Wild Day Out!”: finding wildlife in the Glasgow Botanic Gardens

The Royal Society for the Protection of Birds (RSPB) held “Wild Day Out!” in the Glasgow Botanic Gardens (GBG) on 2nd September 2017. The objectives of the event were: knowing more about wildlife, recording wildlife, public engagement with nature, and partnerships. Included in a range of activities was a Bioblitz during which 71 new species records for the GBG were obtained. Of particular interest were the landhopper Arcitalitrus dorrieni (second record for Glasgow) and the bulrush wainscot moth (Nonagria typhae) (first adult record for Glasgow).

Physiological tolerances of the euterrestrial amphipod Arcitalitrus dorrieni (Hunt) as a key to its geographical distribution? A test using mesocosms

An experimental approach was taken to examine the physiological tolerances that may determine the distribution of the euterrestrial amphipod Arcitalitrus dorrieni, a native of Australia which has established itself in the UK over the last 100 years. Two experiments using mesocosms were carried out over consecutive winters to examine the effects of low temperature and leaf litter sodium content on survival. The role of the microhabitat in buffering environmental temperature was also investigated. It was concluded that A. dorrieni may be prevented from colonising areas of Britain by the effects on populations of low winter temperatures and low habitat sodium concentration. There is considerable buffering of environmental temperatures by the leaf litter and soil layers of the microhabitat, and consequently, mortality of A. dorrieni is related to the depth of microhabitat available for it to utilise in avoiding low temperatures.

Current status of an amphipod invader, Arcitalitrus dorrieni (Hunt, 1925), in Britain

The synanthropic landhopper Arcitalitrus dorrieni (Hunt) is largely restricted to the south-west of Britain although there are isolated populations outside this area. It has been recorded from 60 new 10-km squares since Harding and Sutton (1988) last reviewed its distribution. Some of the new records, particularly in south Wales, could be interpreted as meaning that there has been range expansion in this time. However, the evidence is equivocal. It was not possible to explain the distribution of A. dorrieni in terms of association with native plant species. The main means of dispersal still seems to be synanthropic. Arcitalitrus dorrieni has retained a mainly coastal distribution, with penetration inland restricted to peninsular areas (with some notable exceptions, e.g. populations in London).

Environmental tolerances of an invasive terrestrial amphipod, Arcitalitrus dorrieni (Hunt) in Britain

We investigated key physiological tolerances of the invasive euterrestrial talitrid amphipod (or landhopper) Arcitalitrus dorrieni; desiccation, salt, high and low temperatures. The critical relative humidity below which, A. dorrieni experiences desiccation stress is very high (95–100%), making it completely reliant on the leaflitter/soil microhabitat. It is tolerant of a wide range of (sea) salt concentrations (5–750 mOsmol l −1) but is extremely vulnerable below 5 mOsmol l −1. A. dorrieni does not tolerate low temperatures with a mean lower limit of 1.4 °C, but with no individual surviving <0 °C. The range of upper thermal tolerance (30–37.3 °C) was similar to that found for other landhopper and beachflea species. Based on its tolerance to these environmental factors it is suggested that A. dorrieni has a limited potential to invade further into Britain, being restricted to areas with sufficiently high ion concentrations and mild winters.

The importance of Arcitalitrus dorrieni (Hunt) (Crustacea: Amphipoda: Talitridae) in coniferous litter breakdown

Arcitalitrus dorrieni (Hunt) is a euterrestrial amphipod, native to Australasia, which occurs in several woodland sites in Ireland and Britain. Experiments were carried out to estimate consumption, assimilation and egestion rates of A. dorrieni feeding on Lodgepole pine, Pinus contorta, litter. These figures, together with a model of weight-specific oxygen consumption, were used to estimate the annual percentage of litter fall or carbon utilized by A. dorrieni at a coniferous woodland site in Co. Galway, Ireland. Estimates of 25% suggest that these animals play an important role in mineralization and nutrient exchange in the habitats in which they occur.

Aspects of the life history and reproductive biology of the introduced terrestrial amphipod Arcitalitrus dorrieni (Hunt) at two sites in Co. Galway, Ireland

The reproductive biology of Arcitalitrus dorrieni (Hunt) was investigated over a period of 25 months at a deciduous and a coniferous forest site at Kylemore, Co. Galway, Ireland. The species has an annual, univoltine reproductive cycle with ovigerous females found throughout the year. Recruitment of juveniles begins in May–June with a peak of reproductive activity in August–September. The populations at each site show a bimodal size-distribution for most of the year, with a unimodal distribution in March, April and May. Mortality occurs exponentially, and the life-span is 20–22 months. Mean fecundity was 5·65 eggs per female and was dependent on female size, egg size and brood stage. Brood mortality was 37·5% at Addergoole and 29·8% at Tullywee Bridge.

Biomass, growth, and secondary production of Arcitalitrus dorrieni (Crustacea: Amphipoda: Talitridae) at two sites in Co. Galway, IrelandS

Growth rates, podomere addition, and secondary production of Arcilalitrus dorrieni (Hunt, 1925) populations inhabiting two neighbouring woodland sites at Kylemore, Co. Galway, Ireland, were investigated. One site was a mixed deciduous woodland infested with Rhododendron ponticum. The other a pure coniferous stand of Pinus contorta var. latifolia S. Wats. Seasonal changes in biomass were recorded at the two sites. In both years of the study, maximum biomass was recorded in September. Females had a higher growth rate than males, but growth rates of both males and females were higher at the mixed deciduous site. The number of podomeres on the second antenna was correlated with the size of the animal. The average length of A. dorrieni at each podomere number appeared to change seasonally. Comparisons of mean spring values with mean summer values showed a statistically significant decrease in mean amphipod length for a given podomere number, though this was more marked at the mixed deciduous site. Annual secondary production rates ranged from 5.06 g dry wt m‐2 year‐1at the coniferous site to 14.55 g dry wt m‐2 year‐1 at the mixed deciduous site. P:B values ranged from 2.41 at the coniferous site to 3.01 at the mixed deciduous site. Results are compared between sites and with data from other relevant crustacean species.

Size At Maturity and Sex Ratio of Arcitalitrus Dorrieni (Hunt, 1925) (Amphipoda, Talitridae) At Two Sites in County Galway, Ireland

AbstractAnthropogenic dispersal has led to the introduction of several terrestrial amphipod species to the northern hemisphere. One such species, Arcitalitrus dorrieni (Hunt, 1925), a native of Australasia, is now found in several woodland sites in Ireland and Britain. Aspects of the biology of A. dorrieni were investigated in County Galway over a period of two years and compared between a "typical" mixed deciduous woodland habitat and a more "atypical" coniferous woodland habitat. At both sites, statistically significant differences were found between summer (Aug.-Sep.) size at maturity and winter (Jan.-Apr.) size at maturity, i.e., females were mature at smaller sizes in summer than in winter. Between-site comparisons of August-September data for both years showed that females were mature at a significantly smaller size at the mixed deciduous woodland site. A sex ratio biased in favour of females was recorded on all but one sampling date at each site, though on some dates this bias was not significant. The change in cohort sex ratio at both sites was quite distinct and exhibited the same general pattern. During the recruitment of each cohort, the ratio was biased towards males. As the cohort increased in length, however, the ratio changed to a bias in favour of females, so that by the time a particular cohort entered its breeding period the following year, it was biased firmly in favour of females. Possible reasons for the observed patterns are discussed.

Notes on the occurrence of the introduced landhopperArcitalitrus dorrieni(Hunt, 1925) on Guernsey, Channel Islands

The introduced landhopper Arcitalitrus dorrieni (Hunt, 1925) has been recorded at various locations (woodlands, private gardens and garden centres, disused quarries) throughout the island of Guernsey, Channel Is. Landhoppers were present in the leaf litter of most of the deciduous and coniferous woodlands with one exception. Although it possessed a well developed litter layer, the oak/mixed woodland at Fauxquets valley was devoid of landhoppers. Landhopper populations were less dense in confierous cf. deciduous, leaf litter. Generally the population density of landhoppers was low (21–300 individual m-2) compared with other UK sites (due possibly to the study coinciding with the driest summer for 19 years), but was related to the depth of the litter layer. There was also a direct relationship between the total copper content of the leaf litter/soil and landhopper population density even allowing for different litter thickness. While locating an actual original introduction site is problematic, the date of ...

Biogeography of Alien Amphipods Occurring in Ireland, and Interactions With Native Species

AbstractFive alien species of amphipod Crustacea have arrived in Ireland this century. The terrestrial Arcitalitrus dorrieni (originally Australasian) and freshwater Crangonyx pseudogracilis (North American) were probably accidentally introduced with garden and garden-pond plants respectively. They had arrived by 1936 and 1969 (respectively), but have had very limited expansion of their ranges since then. The marine Corophium sextonae (originally from New Zealand) arrived by 1982, probably by natural means, from south-west Britain. The freshwater Gammarus pulex was deliberately introduced from Britain in the 1950s to enhance fisheries. However, the effects of this species on freshwater fish (as food source or in introducing parasites) have never been assessed. G. tigrinus was probably introduced accidentally from North America by ships during World War 1. These species are replacing the native G. duebenii celticus and G. lacustris, perhaps through a combination of interspecific and intraspecific predation, and greater population growth in certain biotopes. Despite its former abundance and ubiquity in Ireland, the long-term survival of G. d. celticus (a subspecies rare outside Ireland) appears threatened. The only other freshwater amphipod in Ireland, the subterranean Niphargus kochianus irlandicus is unique to Ireland, but too little is known of its biology and ecology to assess its status. The effects of the introduced species on the ecology of freshwater and terrestrial systems in Ireland remain unknown.

The use of the terrestrial amphipod [formula omitted][formula omitted] (Crustacea; Amphipoda; Talitridae) as a potential biomonitor of ambient zinc and copper availabilities in leaf-litter

The mode of metal accumulation employed by the terrestrial talitrid amphipod Arcitalitrus dorrieni (Hunt) feeding on leaf litter variously enriched with the essential metals copper and zinc have been established in the laboratory. Body concentrations of both metals were found to increase over time correlating with the increasing dietary metal concentrations. Field trials to assess the potential use of this amphipod as a terrestrial biomonitor for ambient copper and zinc availabilities in leaf litter are described. The results indicate a potential biomonitoring capacity for zinc (and possibly for copper also). The presently restricted distribution of this species, however, limits its biomonitoring potential to metalliferous areas of S.W. England, but reflects unknown potential in its native Australia.

Ionic regulation in littoral and terrestrial amphipods (Crustacea: Amphipoda: Talitridae)

The regulation of sodium, potassium, magnesium and calcium ions was investigated in four species of talitrid amphipod, Talitrus saltator (Montagu), Orchestia gammarellus (Pallas), Orchestia cavimana (Heller) and Arcitalitrus dorrieni (Hunt). Two acclimation media were used: aerated sea water and agar. There was no appreciable difference in the ionic response to the two acclimation media suggesting that there is no critical role for ion uptake from food (agar) in the gut. Interspecific differences in ionic regulation, especially sodium and calcium, were noted. Sodium regulation patterns showed close agreement with previously reported osmoregulatory curves. Both maritime, supralittoral species ( T. saltator and O. gammarellus) showed hyper-hypo-ionic patterns. Both O. cavimana (a freshwater and estuarine species) and A. dorrieni (a terrestrial species) maintained sodium concentrations in the haemolymph above those in the media over the range investigated. All the species maintained haemolymph calcium at higher concentrations than the external media and this effect was more pronounced in O. cavimana and A. dorrieni. Potassium was also maintained at higher concentrations in the haemolymph although there was great variability. Magnesium concentrations were very low, typically below lO mmol · kg −1 (over external concentrations of 2–60 mmol· kg −1), and always markedly hypo-ionic. These magnesium concentrations are some of the lowest reported for Crustacea. The results are discussed with reference to the availability of ions in the littoral, freshwater and terrestrial habitats, with reference to other crustacean groups and in relation to the proposed evolutionary history of the group.

O 2-binding by the blood of the landhopper, Arcitalitrus dorrieni (Hunt) (Crustacea: Amphipoda)

1. 1. The O 2-binding characteristics of the blood of the euterrestrial amphipod (landhopper) Arcitalitrus dorrieni have been studied. 2. 2. The blood exhibited a low O 2 affinity, with a p 50 (at pH = 7.8) of 21.4 torr (10°C). Affinity decreased with an increase in temperature at constant pH (Δ H = − 79.4kJ/mol) but the Bohr factor ( Δ log P 50/Δ pH = −0.67) was unaffected. 3. 3. The O 2-carrying capacity of the blood was moderate (1.51 ml/100 ml) 4. 4. The results support the hypothesis that the blood of terrestrial amphipods is characterized by having a low affinity pigment.

Osmoregulation in littoral and terrestrial talitroidean amphipods (Crustacea) from Britain

Osmoregulation was investigated in both aerated seawater and on saturated sand in four species of talitrid amphipods, Talitrus saltator (Montagu), Orchestia gammarellus (Pallas), Orchestia cavimana (Heller) and Arcitalitrus dorrieni (Hunt). The Osmoregulation of one species of intertidal hyalid amphipod Hyale nilssoni (Rathke) was also investigated. Appreciable differences were demonstrated in the osmoregulatory abilities of the species. Whilst the marine supralittoral species O. gammarellus and T. saltator demonstrated the ability to hypo-regulate at higher external concentrations ( > 800 mOsm), they hyper-regulated at lower concentrations, maintaining the haemolymph concentration between 750–850 mOsm. The fresh-water and estuarine supralittoral species O. cavimana and the landhopper A. dorrieni did not have this capacity; both these species maintained the haemolymph hyper-osmotic between external concentrations of 50–900 mOsm. The intertidal H. nilssoni also demonstrated this hyper-osmotic regulation pattern. Hyper-regulation in O. cavimana between external concentrations of 15–290 mOsm was at least partially mediated by the production of hypo-osmotic urine from the antennary gland. The landhopper A. dorrieni produced isosmotic urine as did the hyper-hypo regulating O. gammarellus. There was, however, some evidence that hyper-regulating T. saltator may also produce hypo-osmotic urine. Survivals under different acclimation regimes largely reflect the original habitat of the species: the estuarine/marine supralittoral species were tolerant of a wide range of salinities in water and on sand: the freshwater species showed reduced survival at higher salinities (1200 mOsm) but higher survival than its marine relations in freshwater (<20 mOsm). The landhopper was tolerant of a wide range of salinities but survivals at low (<50 mOsm) and high ( > 900 mOsm) salinities were greater on sand than in water. The results are discussed in relation to the habitats of the species and in relation to the presumed evolutionary history of the group as a whole.

Evaporative water loss under desiccation stress in semiterrestrial and terrestrial amphipods (Crustacea: Amphipoda: Talitridae)

Transpiration rates were measured in both still and moving air systems in three talitrid amphipods, Orchestia gammarellus (Pallas), Talitrus saltator (Montagu), and Arcitalitrus dorrieni (Hunt). Significant differences were demonstrated between the rates of water loss in the three species. The terrestrial A. dorrieni exhibited much higher rates than the supralittoral species. In still air at 15 °C and 75% r.h., for example, the mean rate in A. dorrieni was 0.183 ± 0.008 mg· h −1· mg wet wt −1 compared with 0.111 ± 0.003 for Orchestia gammarellus and 0.106 ± 0.003 for Talitrus saltator. In moving air, regression lines plotting weight-specific rates of water loss against saturation deficit were significantly different between the three species in their slope. The regression line for Arcitalitrus dorrieni ( R= - 0.0514 + 0.0481 φ) was much steeper than that for Orchestia gammarellus ( R = 0.0465 + 0.0187 φ) and for Talitrus saltator ( R = 0.033 + 0.0128 φ). Arcitalitrus dorrieni therefore showed the highest rates ofwater loss, under conditions of high desiccation stress, but there was no clear difference between the species at low values of saturation deficit. Mean calculated permeabilities reflect this trend: A. dorrieni, 0.0403 ± 0.0009 mg · h −1· mg wet wt −1 · mm Hg −1, Orchestia gammarellus, 0.0247 ± 0.0008, and Talitrus saltator, 0.0188 − 0.0006. Juvenile supralittoral talitrids of approximately the same body size as Arcitalitrus dorrieni consistently showed higher weight-specific rates of water loss in still air than adults of their own species, but the rates were usually lower than those of adult A. dorrieni. The very high rates of transpiration in A. dorrieni are not explicable by purely allometric considerations. The results are discussed with reference to the ecology and natural habitats of the species investigated and in relation to the colonization of the terrestrial habitat.

Copper and zinc in an ecological series of talitroidean Amphipoda (Crustacea).

Cu and Zn concentrations were determined for the following talitroidean amphipods, Hyale nilssoni (Rathke), Talitrus saltator (Montagu), Talorchestia deshayesii (Audouin), Orchestia mediterranea Costa, O. gammarellus (Pallas), O cavimana Heller and Arcitalitrus dorrieni (Hunt) in September 1986 from sites in W. Britain (mostly Scottish). To minimize size effects, only animals >2mg body dry weight were included in analyses. Only Talorchestia (Cu & Zn) and O. cavimana (Zn) showed any residual relationship between metal concentration and dry weight. Log transformed data for concentrations of each metal against log dry wt. in all species were compared by ANCOVA. Copper and zinc concentrations of males and females were not significantly different in O. gammarellus, O. mediterranea and T. deshayesii, though Cu (but not Zn) concentrations differed with sex in O. cavimana. The order of species when ranked according to an ascending series of Cu concentrations (at standard body weight) reflected their ecological zonation from sea to land closely, with species living proximal to the sea having lowest Cu concentrations. The 6 talitrid species all had similar Zn concentrations but the Zn concentration of H. nilssoni was considerably lower. There was a relationship between Cu and Zn concentrations in individuals of only one species (O. gammarellus). Data on Cu and Zn concentrations for O. gammarellus derived from the same site in September 1983 were almost exctly the same as in September 1986. The possible impact of seasonal variation on haemocyanin levels is discussed.

Respiration in air and water of some semi- and fully terrestrial talitrids (Crustacea: Amphipoda: Talitridae)

Aerial and aquatic rates of oxygen consumption were determined for the semi-terrestrial beachfleas Orchestia mediterranea (Costa), O. gammarellus (Pallas) and O. cavimana (Heller) and the fully terrestrial landhopper Arcitalitrus dorrieni (Hunt) over the temperature range (10–30 °C). There was little difference between the rates for Orchestia gammarellus and O. mediterranea in air and water but the rates of aerial oxygen consumption of both O. cavimana and Arcitalitrus dorrieni were significantly reduced on immersion. All animals were able to survive prolonged submersion with the exception of A. dorrieni. The aerial and aquatic oxygen consumption rates of all species increased directly with an increase in experimental temperature. The ability of talitrid amphipods to maintain an aerial rate of oxygen consumption following immersion can be correlated to some extent with the degree of emancipation from the aquatic environment. The mechanisms involved, however, are far from clear.

A comparative study of the gill area relationships in some talitrid amphipods

The total gill area and gill distribution of seven talitrid species taken from a variety of habitats have been studied. In the sandhoppers, Talitrus and Talorchestia, and in the landhopper, Arcitalitrus dorrieni, the greatest gill area is invested in the posterior gills (G6) whereas in the beachflea, Orchestia spp., G2 has the greatest area. Gills 3, 4 and 5 are characteristically small and G7 is consistently absent in all the species studied. Gill structure and deployment patterns are, in general, quite conservative within the Talitridae. The gills of A. dorrieni are, however, complex in shape and are more convoluted than in the other species studied. Gill area/body dry weight relationships were established for each species and are compared with previously published data. The Talitridae show a reduction in total gill area compared with most aquatic amphipods. It was observed, however, that the slopes of the calculated regression lines were significantly different between the sandhopper and beachflea gene...

On the status ofArcitalitrus dorrieni(Crustacea: Amphipoda) on the island of Colonsay, Inner Hebrides

The presence of the landhopper Arcitalitrus dorrieni (Hunt) is reported on the island of Colonsay, Inner Hebrides. It is widely distributed there amongst deciduous leaf litter in forested areas but also occurs in bracken litter and scrub grassland. The species is an introduction from Australia, doubtless transported inadvertently among plants brought to the gardens at Colonsay House. It is, however, not restricted to the ornamental plantings but has colonized native woodland. Maximum population density recorded under leaf litter was 680 m2. Amphipods avoid waterlogged or dry situations preferring to burrow in moist soil under litter from deciduous trees. Coniferous woodlands are more sparsely colonized. Rate of spread (minimum) from the original locus is calculated at c. 25 m/year. Arcitalitrus may prefer to eat sycamore leaves (cf. oak, beech). Ovigerous females are reported for May but no evidence exists for a release of young any earlier in the year. Immature amphipods seem to live more covert lives in the soil beneath the superficial litter layer. Eggs are relatively large and few in number. Amphipods may avoid ants but may have a mite living in phoretic or ectoparasitic association.