Zooplankton diversity and assemblages in arid zone rivers of the Lake Eyre Basin, Australia

2006 ◽  
Vol 57 (1) ◽  
pp. 49 ◽  
Author(s):  
Russell J. Shiel ◽  
Justin F. Costelloe ◽  
Julian R. W. Reid ◽  
Peter Hudson ◽  
Joan Powling
Keyword(s):  
Seasonal Changes ◽  
Arid Zone ◽  
Early Summer ◽  
Taxon Richness ◽  
Ecosystem Structure ◽  
Regression Analyses ◽  
Flood Events ◽  
Assemblage Composition ◽  
Boom And Bust ◽  
Three Rivers

The responses of zooplankton assemblages in arid zone rivers to seasonal changes, flow events, drying and water quality changes are fundamental to our understanding of these unregulated rivers. For three years the zooplankton and littoral microfauna in three rivers in the Lake Eyre Basin were studied. A diverse assemblage was discovered with a total of 398 identifiable taxa being recorded, consisting of 72 protist, 227 rotifer and 93 microcrustacean taxa. Zooplankton diversity was highest in a boom phase during, or in the summer following, a large flood. The rotifer assemblage dominated during, or soon after, periods of flow. However, during the winter and early summer, there was a decline in rotifer taxon richness and abundance accompanied by an increase in microcrustacean taxon richness and abundance. The winter samples occurred during the recession of a large flood and the early summer samples during periods of no flow. These changes suggested the involvement of a strong annual cycle of ecosystem structure evident within the longer term patterns of boom and bust driven by the timing and size of flood events. Multivariate and regression analyses found that salinity was a significant and independent driver of assemblage composition.

Annual Variations in Rheotactic Behaviour and Seawater Adaptability in Landlocked Arctic Char (Salvelinus alpinus)

1992 ◽  
Vol 49 (3) ◽  
pp. 448-452 ◽  
Author(s):  
Monika Schmitz
Keyword(s):  
Seasonal Changes ◽  
Salvelinus Alpinus ◽  
Challenge Test ◽  
Early Summer ◽  
Rapid Decrease ◽  
Arctic Char ◽  
Migratory Behaviour ◽  
Annual Variations ◽  
Seawater Tolerance ◽  
Seawater Challenge

The existence of basic smoltification characteristics, measured by means of seasonal changes in rheotactic behaviour and seawater adaptability, was studied from February to November in 1- and 2-yr-old landlocked Arctic char (Salvelinus alpinus). Up- and downstream directed movements were monitored in an annular stream tank at a water velocity of 0.2 m/s. A 48-h seawater challenge test using 25‰ seawater was performed at monthly intervals throughout the year to assess seawater adaptability. The 1-yr-old char displayed mainly nondirectional behaviour during spring, but from August onwards the movements were predominantly against the current. Seawater performance improved slightly in this group in May and June. The 2-yr-old char progressively developed a downstream behaviour and exhibited an increased seawater adaptability during spring and early summer. In late August, a marked reversal in rheotactic behaviour occurred, followed by a rapid decrease in seawater tolerance. The results demonstrate that seasonal changes in seawater adaptability and changes in migratory behaviour which were directionally consistent with smolting still exist in a population of Arctic char that has been landlocked for about 6000 yr.

scholarly journals Latitudinal patterns in intertidal ecosystem structure in West Greenland suggest resilience to climate change

2021 ◽  
Author(s):  
Jakob Thyrring ◽  
Susse Wegeberg ◽  
Martin E Blicher ◽  
Dorte Krause-Jensen ◽  
Signe H&oslashgslund ◽  
...  
Keyword(s):  
Climate Change ◽  
Ascophyllum Nodosum ◽  
Tidal Range ◽  
Environmental Drivers ◽  
Small Scale ◽  
Ecosystem Structure ◽  
Assemblage Composition ◽  
West Greenland ◽  
Functional Changes ◽  
Time Substitution

Climate change has ecosystem-wide cascading effects. Little is known, however, about the resilience of Arctic marine ecosystems to environmental change. Here we quantify and compare large-scale patterns in rocky intertidal biomass, coverage and zonation in six regions along a north-south gradient of temperature and ice conditions in West Greenland (60-72°N). We related the level and variation in assemblage composition, biomass and coverage to latitudinal-scale environmental drivers. Across all latitudes, the intertidal assemblage was dominated by a core of stress-tolerant foundation species that constituted >95% of the biomass. Hence, canopy-forming macroalgae, represented by Fucus distichus subsp. evanescens and F. vesiculosus and, up to 69 °N, also Ascophyllum nodosum, together with Semibalanus balanoides, occupied >70% of the vertical tidal range in all regions. Thus, a similar functional assemblage composition occurred across regions, and no latitudinal depression was observed. The most conspicuous difference in species composition from south to north was that three common species (the macroalgae Ascophyllum nodosum, the amphipod Gammarus setosus and the gastropod Littorina obtusata) disappeared from the mid-intertidal, although at different latitudes. There were no significant relationships between assemblage metrics and air temperature or sea ice coverage as obtained from weather stations and satellites, respectively. Although the mean biomass decreased >50% from south to north, local biomass in excess of 10 000 g ww m-2 was found even at the northernmost site, demonstrating the patchiness of this habitat and the effect of small-scale variation in environmental characteristics. Hence, using the latitudinal gradient in a space-for-time substitution, our results suggest that while climate modification may lead to an overall increase in the intertidal biomass in north Greenland, it is unlikely to drive dramatic functional changes in ecosystem structure in the near future. Our dataset provides an important baseline for future studies to verify these predictions for Greenlands intertidal zone.

The ecology of sympatric scincid lizards (Ctenotus) in arid South Australia

1998 ◽  
Vol 46 (6) ◽  
pp. 617 ◽  
Author(s):  
J. L. Read
Keyword(s):  
Home Range ◽  
Environmental Conditions ◽  
Plant Material ◽  
Reproductive Effort ◽  
Arid Zone ◽  
South Australia ◽  
Early Summer ◽  
Home Ranges ◽  
Local Species ◽  
Olympic Dam

Ctenotus skinks are the most diverse and abundant diurnal reptile genus at Olympic Dam, in the South Australian arid zone. The home range, demography, reproduction and diet of five syntopic Ctenotus species was studied over a 6-year period in chenopod shrubland. Longevity frequently exceeded three years in C. regius, four years in C. schomburgkii and five years in C. leonhardii, with a 7-year-old specimen of C. leonhardii being recorded. Females of most species tended to be larger and lived longer than males. Two eggs were typically laid by each species in early summer. Annual reproductive effort, particularly in C. leonhardii, varied considerably depending upon the prevailing environmental conditions. All local species apparently occupied home ranges, with maximum recapture radii in different species of 40–60 m. Ctenotus appear to be unspecialised insectivores, although plant material and lizards are sometimes eaten by the larger species.

Population Dynamics and Movement Patterns of Bolam's Mouse, Pseudomys bolami, at Roxby Downs, South Australia.

1998 ◽  
Vol 20 (3) ◽  
pp. 353
Author(s):  
K.E. Moseby ◽  
J.L. Read
Keyword(s):  
Arid Zone ◽  
Sand Dunes ◽  
South Australia ◽  
Breeding Strategy ◽  
Early Summer ◽  
Ecological Data ◽  
Winter Rainfall ◽  
Land Systems ◽  
Single Night ◽  
Time Of Year

Basic ecological data were collected on Bolam's mouse, Pseudomys bolami, during a six year trapping study at Roxby Downs in northern South Australia. Pseudomys bolami inhabited mixed arid land systems in the Roxby Downs area, sheltering in the longitudinal orange sand dunes but foraging at night principally on the adjacent chenopod swales. Distances of up to 334m were traversed in a single night and recapture rates were high within trapping sessions but low between sessions suggesting wide-ranging movements and short-term residency. Dietary observations imply an omnivorous diet. Whilst the closely related P. hermannsburgensis is regarded as having an opportunistic breeding strategy, P. bolami reproduced opportunistically but also regularly in spring and early summer. Different reproductive strategies may be influenced by the latitudinal distribution of P. bolami near the southern margin of the arid-zone, where rainfall can occur at any time of year but winter rainfall is more predictable. This contrasts with P. hermannsburgensis, which inhabits more northerly arid areas where rainfall is erratic and unpredictable. There was a 10 fold fluctuation in P. bolami captures over the trapping period with numbers of P. bolami and house mice, Mus domesticus peaking 12 months after above average rains during 1992. Rodent captures remained high for two years afterwards. Although P. bolami persisted throughout the study period, M. domesticus was only present when conditions were above average. Trap success of P. bolami or M. domesticus did not vary between the five sub habitats at the 1 ha study site. However, trap success of P. bolami was positively related to vegetation cover, particularly cover of low bluebush, Maireana astrotricha. Maireana astrotricha may be important in providing both food and cover for P. bolami, a scenario consistent with the utilisation of spinifex, Triodia spp. by P. hermannsburgensis in the northern arid-zone. Past over- grazing of chenopod shrublands may have reduced cover and contributed to the suggested decline in the distribution of P. bolami.

Seasonal changes in glucose tolerance and glycogen disposition in a lizard

1963 ◽  
Vol 204 (4) ◽  
pp. 677-680 ◽  
Author(s):  
Anthony Di Maggio ◽  
Herbert C. Dessauer
Keyword(s):  
Blood Glucose ◽  
Glucose Tolerance ◽  
Seasonal Changes ◽  
Liver Glycogen ◽  
Early Summer ◽  
Anolis Carolinensis ◽  
Fasting Level ◽  
Glucose Injection ◽  
Different Seasons ◽  
Autumn And Winter

Forty milligrams of glucose in 0.4 ml of water were injected intraperitoneally into fasted adult male lizards, Anolis carolinensis, in different seasons. At intervals of 3 hr to 5 days following injection lizards were sacrificed and their tissues analyzed for carbohydrate. Blood glucose returned to fasting level in less than 36 hr in spring and summer but remained above fasting level for over 2 days during autumn and winter. Generally, 4–6 g of glycogen were deposited per 100 g of liver per day. Greater quantities of glycogen were deposited in liver during autumn than in other seasons. The rate of decrease of liver glycogen was slowest in autumn and winter. Extrahepatic glycogen did not increase after glucose injection in early summer and autumn but rose significantly in winter and spring. The decreased "glucose tolerance" of Anolis and its increased capacity to store glycogen in autumn and winter may be due to a decreased rate of carbohydrate oxidation in these seasons.

Seasonal changes in body composition of mature female caribou and calves (Rangifer tarandus groenlandicus) on an arctic island with limited winter resources

1987 ◽  
Vol 65 (5) ◽  
pp. 1149-1157 ◽  
Author(s):  
J. Z. Adamczewski ◽  
C. C. Gates ◽  
R. J. Hudson ◽  
M. A. Price
Keyword(s):  
Body Composition ◽  
Body Fat ◽  
Seasonal Changes ◽  
Rangifer Tarandus ◽  
Total Body Weight ◽  
Mature Female ◽  
Early Summer ◽  
Winter Mortality ◽  
Total Body ◽  
Rangifer Tarandus Groenlandicus

Twelve collections of mature female caribou and calves (Rangifer tarandus groenlandicus) were conducted between June 1982 and June 1984 on Coats Island, Northwest Territories, Canada, to study seasonal changes in body composition in this winter mortality limited population. Mature females depleted reserves of dissectible fat and muscle considerably during both winters of the study, particularly the second, when nearly all dissectible fat and 32% of estimated fall muscle mass were lost. Recovery of fat and muscle was rapid during the two summers, because of good quality forage and little environmental disturbance. Lactation appeared to slow fattening in early summer 1983, but by October females achieved fatness similar to that in 1982, when a majority of females in summer and fall were nonlactating. Low rumen fill and consistently high fat and muscle levels in fall 1982 and 1983 suggested that mature females then approached "set points" in body fat and muscle content. Calves grew rapidly in summer; most of this growth was lean tissue, and their losses of body fat and muscle were severe during winter. Mature females and calves increased rumen fill substantially over winter to compensate for highly fibrous food. This made total body weight a much poorer predictor of condition than carcass weight. The liver, kidneys, and empty rumen were heaviest in summer in response to high forage quality. Poor condition of females was associated with light fetuses in May 1984.

Seasonal changes in mycorrhizal and fibrous-textured root biomass in 23- and 180-year-old Pacific silver fir stands in western Washington

1980 ◽  
Vol 10 (4) ◽  
pp. 523-529 ◽  
Author(s):  
Kristiina A. Vogt ◽  
Robert L. Edmonds ◽  
Charles C. Grier ◽  
Stephen R. Piper
Keyword(s):  
Seasonal Changes ◽  
Root Biomass ◽  
Fine Root Biomass ◽  
Early Summer ◽  
Silver Fir ◽  
Fibrous Root ◽  
Mycorrhizal Root ◽  
Young Stand ◽  
Soil Temperatures ◽  
Mycorrhizal Roots

Seasonal changes in mycorrhizal and fibrous root biomass were examined in 23- and 180-year-old Abiesamabilis (Dougl.) Forbes stands. Both stands had similar patterns of change in mycorrhizal root biomass with the lowest level in the summer and highest in the fall. The fall peak of fine root biomass was the result of increased mycorrhizal and not fibrous root biomass. High levels of active mycorrhizal root biomass were measured during the winter months under a snowpack at soil temperatures of 1 °C. In both stands mycorrhizal roots comprised the largest proportion of the weight of fine roots during the winter (29%) and the lowest during the summer (2%). Except during early summer, the old stand had significantly higher levels of mycorrhizal root biomass in comparison to the young stand throughout the year.

Seasonal dynamics and life cycle of Heterotrissocladius marcidus (Diptera: Chironomidae) in high altitude lakes (High Tatra Mts, Slovakia)

Biologia ◽  
2015 ◽  
Vol 70 (7) ◽  
Author(s):  
Katarína Goffová ◽  
Peter Bitušík ◽  
Zuzana Čiamporová-Zatóvičová ◽  
Dana Bukvová ◽  
Ladislav Hamerlík
Keyword(s):  
Life Cycle ◽  
Seasonal Dynamics ◽  
Seasonal Changes ◽  
Alpine Lakes ◽  
Early Summer ◽  
Larval Abundance ◽  
Tatra Mountains ◽  
Tatra Mts ◽  
Summer Decline ◽  
High Tatra Mountains

AbstractWe estimated the seasonal dynamics and life cycle of the chironomid Heterotrissocladius marcidus (Walker, 1856) in three alpine lakes in the High Tatra Mountains (Central Europe). H. marcidus had univoltine cycle in all lakes surveyed and seasonal changes of density showed an early summer and an autumn peak interrupted by a mid-summer decline of larval abundance. Our results indicate that phenology of H. marcidus is sensitive to thermal regime and local differences in lake water temperature can lead to differences of the life history within the same population

scholarly journals Light conditions alter accumulation of long chain polyprenols in leaves of trees and shrubs throughout the vegetation season.

2005 ◽  
Vol 52 (1) ◽  
pp. 233-241 ◽  
Author(s):  
Agnieszka Bajda ◽  
Tadeusz Chojnacki ◽  
Józefina Hertel ◽  
Ewa Swiezewska ◽  
Jacek Wójcik ◽  
...  
Keyword(s):  
Light Intensity ◽  
Seasonal Changes ◽  
Leaf Blade ◽  
Early Summer ◽  
Light Conditions ◽  
Natural Habitats ◽  
Vegetation Season ◽  
The Difference ◽  
Trees And Shrubs ◽  
Long Chain

In many plants belonging to angiosperms and gymnosperms the accumulation in leaves of long chain polyprenols and polyprenyl esters during growth in natural habitats depends on the light intensity. The amount of polyprenols in leaves is also positively correlated with the thickness of the leaf blade (SLA, specific leaf area). The polyprenol content of leaves shows seasonal changes with a maximum in autumn and a minimum in early summer with the difference between poorly and well illuminated plants persisting throughout the vegetation season.

scholarly journals Changes in Biomass and Diversity of Soil Macrofauna along a Climatic Gradient in European Boreal Forests

Insects ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 94
Author(s):  
Mikhail V. Kozlov ◽  
Vitali Zverev ◽  
Vladimir I. Gusarov ◽  
Daniil I. Korobushkin ◽  
Nina P. Krivosheina ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Late Summer ◽  
Average Density ◽  
Early Summer ◽  
Latitudinal Gradients ◽  
Feeding Guilds ◽  
Mean Annual Temperature ◽  
Ecosystem Structure ◽  
Soil Macrofauna ◽  
The North

Latitudinal gradients allow insights into the factors that shape ecosystem structure and delimit ecosystem processes, particularly climate. We asked whether the biomass and diversity of soil macrofauna in boreal forests change systematically along a latitudinal gradient spanning from 60° N to 69° N. Invertebrates (3697 individuals) were extracted from 400 soil samples (20 × 20 cm, 30 cm depth) collected at ten sites in 2015–2016 and then weighed and identified. We discovered 265 species living in soil and on the soil surface; their average density was 0.486 g d·w·m−2. The species-level diversity decreased from low to high latitudes. The biomass of soil macrofauna showed no latitudinal changes in early summer but decreased towards the north in late summer. This variation among study sites was associated with the decrease in mean annual temperature by ca 5 °C and with variation in fine root biomass. The biomass of herbivores and fungivores decreased towards the north, whereas the biomass of detritivores and predators showed no significant latitudinal changes. This variation in latitudinal biomass patterns among the soil macrofauna feeding guilds suggests that these guilds may respond differently to climate change, with poorly understood consequences for ecosystem structure and functions.

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