Reproductive strategy and growth of the Australian smelt, Retropinna semoni (Weber) (Pisces : Retropinnidae), and the olive perchlet, Ambassis nigripinnis (De Vis) (Pisces : Ambassidae), in Brisbane, south-eastern Queensland

1985 ◽  
Vol 36 (3) ◽  
pp. 329 ◽  
Author(s):  
DA Milton ◽  
AH Arthington
Keyword(s):  
Native Species ◽  
Juvenile Fish ◽  
Open Water ◽  
Water Levels ◽  
South Eastern ◽  
Large Populations ◽  
Coastal Streams ◽  
Littoral Vegetation ◽  
Suitable Habitats ◽  
Eggs And Larvae

The reproductive biology and growth of R. semoni and A. nigripinnis were studied in Brisbane, south- eastern Queensland, over a 20-month period (1981-1982). R. semoni began to breed in winter at water temperatures exceeding 15�C, reflecting its salmoniform affinities and temperate distribution. A. nigripinnis, a subtropical species of Indo-Pacific origin, required a period of rising temperature before breeding began in spring at 22�C. Both species concentrated their breeding activity into the months that precede summer storms and high, variable stream discharges, which can generate fluctuating water levels, destruction of weedbeds and instability of the stream substrate. Pre-flood spawning also occurs in three other small-bodied native species in the region, and appears to have adaptive value in the seasonally unstable environments of coastal streams. Dispersal of juvenile fish may be facilitated by rising water levels during summer months following spawning. R. semoni grew faster and to larger sizes than A. nigripinnis and growth of both species was adequately described by the von Bertalanffy equation. Male and female R. semoni and male A. nigripinnis live and breed for 2 years but female A. nigripinnis survive and may breed into their third year. These patterns of survivorship and reproduction are consistent with the contention that natural mortality is higher in open-water foragers such as R. semoni than in species like A. nigripinnis, which tends to forage amongst littoral vegetation and in mid-water. Differences in the sizes of eggs and larvae of the two species are also consistent with the probability that they experience different relative exposure to predation. These and other attributes, coupled with pre-flood spawning, enable both species to achieve large populations in suitable habitats within coastal streams, in spite of their relatively low fecundities.

Reproductive strategy and growth of the crimson-spotted rainbowfish, Melanotaenia splendida fluviatilis (Castelnau) (Pisces : Melanotaeniidae) in south-eastern Queensland

1984 ◽  
Vol 35 (1) ◽  
pp. 75 ◽  
Author(s):  
DA Milton ◽  
AH Arthington
Keyword(s):  
Reproductive Cycle ◽  
Reproductive Strategy ◽  
Juvenile Fish ◽  
Water Levels ◽  
Juvenile Survival ◽  
Annual Reproductive Cycle ◽  
South Eastern ◽  
Coastal Streams

M. s. fluvlatilis has a well-defined annual reproductive cycle in south-eastern Queensland. Spawning is confined to October, November and December, with the peak in October, before the onset of summer floods and unpredictable water levels in coastal streams. Juvenile fish grow rapidly and reach maturity in the year following hatching. Growth in both sexes conforms to the von Bertalanfi model, but males grow faster and to larger sizes than females. Differences in the reproductive strategy of M. s. fluviatilis in southern Queensland and that of the more northern subspecies, M. s. splendida, may be related to the relative predictability of flooding, and hence to the probability of egg and juvenile survival, in the two areas. M. s. fluviatilis has low fecundity but the species is, nevertheless, abundant in suitable environments.

Ice-free area expansion compounds the non-native species threat to Antarctic terrestrial biodiversity

2019 ◽  
Author(s):  
Grant Duffy ◽  
Jasmine R Lee
Keyword(s):  
Human Activity ◽  
Native Species ◽  
Climate Scenario ◽  
Climatic Environment ◽  
Species Establishment ◽  
Suitable Habitats ◽  
Terrestrial Biodiversity ◽  
A Site ◽  
Area Expansion ◽  
Free Area

Warming across ice-covered regions will result in changes to both the physical and climatic environment, revealing new ice-free habitat and new climatically suitable habitats for non-native species establishment. Recent studies have independently quantified each of these aspects in Antarctica, where ice-free areas form crucial habitat for the majority of terrestrial biodiversity. Here we synthesise projections of Antarctic ice-free area expansion, recent spatial predictions of non-native species risk, and the frequency of human activities to quantify how these facets of anthropogenic change may interact now and in the future. Under a high-emissions future climate scenario, over a quarter of ice-free area and over 80 % of the ~14 thousand km2 of newly uncovered ice-free area could be vulnerable to invasion by one or more of the modelled non-native species by the end of the century. Ice-free areas identified as vulnerable to non-native species establishment were significantly closer to human activity than unsuitable areas were. Furthermore, almost half of the new vulnerable ice-free area is within 20 km of a site of current human activity. The Antarctic Peninsula, where human activity is heavily concentrated, will be at particular risk. The implications of this for conservation values of Antarctica and the management efforts required to mitigate against it are in need of urgent consideration.

Relation Between Egg Size, Growth, and Natural Mortality of Larval Fish

1975 ◽  
Vol 32 (12) ◽  
pp. 2503-2512 ◽  
Author(s):  
D. M. Ware
Keyword(s):  
Death Rate ◽  
Egg Size ◽  
Larval Fish ◽  
Juvenile Fish ◽  
Survival Rates ◽  
Fish Eggs ◽  
Trophic Relations ◽  
Size Growth ◽  
Dependent Growth ◽  
Eggs And Larvae

A set of density-dependent growth and survivorship equations is derived from evidence that the instantaneous death rate in the sea is inversely proportional to particle size. The survivorship equation reproduces several well-known phenomena observed in fish populations. It predicts: 1) that winter and spring spawning species ought to produce larger eggs than summer spawners, 2) that it is advantageous for species that spawn in batches to produce progressively smaller eggs in spring and summer, and 3) that the death rate of a cohort of fish should decrease continuously as the survivors grow and approach the critical size.The biological basis for the observed variation in the size of pelagic fish eggs and larvae is thought to be due primarily to trophic relations within the pelagic community. It is suggested from what is known of the relative abundance and foraging capabilities of different sized particles, that the survival rates of larval and juvenile fish should increase as they grow and occupy a progressively higher position in the food chain.

scholarly journals Model Predictive Control of a River Reach with Weirs

10.29007/1nnf ◽  
2018 ◽  
Author(s):  
Klaudia Horváth ◽  
Bart van Esch ◽  
Jorn Baayen ◽  
Ivo Pothof ◽  
Jan Talsma ◽  
...  
Keyword(s):  
Decision Support ◽  
Convex Optimization ◽  
Decision Support System ◽  
Model Predictive Control ◽  
Predictive Control ◽  
Support System ◽  
Water System ◽  
Open Water ◽  
Global Optimum ◽  
Water Levels

A decision support system for water management based on convex optimization, RTC-Tools 2, is applied for a water system containing river branches connected by weirs. The advantage of convex optimization is the ability of finding the global optimum, which makes the decision support system robust and deterministic. In this work the convex modeling of open water channels and weirs is presented. The decision support system is implemented for a river made of 12 river reaches divided by movable weirs. It is shown how the discharge wave is dispatched in the river without the water levels exceeding the bounds by controlling the weir heights. After this test the optimization can be applied to a realistic numerical model and model predictive control can be implemented.

scholarly journals Ophyiulus in Victoria: results of millipede surveys from south-eastern Australia

2015 ◽  
Vol 127 (2) ◽  
pp. 69
Author(s):  
Briony A. Norton ◽  
Linda J. Thomson ◽  
Michael A. Nash
Keyword(s):  
Species Identification ◽  
Preliminary Data ◽  
Native Species ◽  
South Eastern ◽  
Eastern Australia ◽  
The Future ◽  
South Eastern Australia

The composition and ecology of the millipede fauna of Victoria remain poorly understood. We collected millipedes as part of a series of ecological arthropod surveys across south-eastern Australia, focusing mainly on Victoria. These samples almost exclusively contained millipedes from the introduced order Julida. We pursued species identification of the julids when it became apparent there were species other than the well-recorded Ommatoiulus moreleti (Lucas, 1860) (Portuguese millipede) in the samples. The majority of specimens were O. moreleti, but we also detected at least one species of Cylindroiulus Verhoeff, 1894, as well as an Ophyiulus Berlese, 1884, species, specimens of which have been identified as Ophyiulus cf. targionii. These are the first Ophyiulus records for Victoria to our knowledge. We present preliminary data on the abundance through the year of Ophyiulus. This is the first study to examine this species in Victoria and little is currently known about its likely impact on agriculture or on native species. Monitoring and research of the species in the future is therefore warranted.

scholarly journals Regulation of Vegetation and Evapotranspiration by Water Level Fluctuation in Shallow Lakes

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2651
Author(s):  
Qiang Liu ◽  
Liqiao Liang ◽  
Xiaomin Yuan ◽  
Sirui Yan ◽  
Miao Li ◽  
...  
Keyword(s):  
Water Level ◽  
Open Water ◽  
Water Area ◽  
Water Level Fluctuation ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Water Evaporation ◽  
Level Fluctuation ◽  
Open Water Area ◽  
Annual Scale

Water level fluctuations play a critical role in regulating vegetation distribution, composition, cover and richness, which ultimately affect evapotranspiration. In this study, we first explore water level fluctuations and associated impacts on vegetation, after which we assess evapotranspiration (ET) under different water levels. The normalized difference vegetation index (NDVI) was used to estimate the fractional vegetation cover (Fv), while topography- and vegetation-based surface-energy partitioning algorithms (TVET model) and potential evaporation (Ev) were used to calculate ET and water evaporation (Ep). Results show that: (1) water levels were dramatically affected by the combined effect of ecological water transfer and climate change and exhibited significant decreasing trends with a slope of −0.011 m a−2; and (2) as predicted, there was a correlation between water level fluctuation at an annual scale with Phragmites australis (P. australis) cover and open-water area. Water levels also had a controlling effect on Fv values, an increase in annual water levels first increasing and then decreasing Fv. However, a negative correlation was found between Fv values and water levels during initial plant growth stages. (iii) ET, which varied under different water levels at an annual scale, showed different partition into transpiration from P. australis and evaporation from open-water area and soil with alterations between vegetation and open water. All findings indicated that water level fluctuations controlled biological and ecological processes, and their structural and functional characteristics. This study consequently recommends that specifically-focused ecological water regulations (e.g., duration, timing, frequency) should be enacted to maintain the integrity of wetland ecosystems for wetland restoration.

scholarly journals New knowledge about species of the genus Chaerophyllum (Apiaceae) in Latvia

Botanica ◽  
2018 ◽  
Vol 24 (2) ◽  
pp. 115-123
Author(s):  
Pēteris Evarts-Bunders ◽  
Gunta Evarte-Bundere
Keyword(s):  
Alien Species ◽  
Native Species ◽  
Human Settlements ◽  
Herbarium Material ◽  
South Eastern ◽  
Root Vegetable ◽  
New Knowledge ◽  
Critical Revision

Abstract Evarts-Bunders P., Evarte-Bundere G., 2018: New knowledge about species of the genus Chaerophyllum (Apiaceae) in Latvia. - Botanica, 24(2): 115-123. The genus Chaerophyllum belongs to the Apiaceae family, which is one of the most complicated and difficult to identify in Latvia. There are five species verified by herbarium materials known in Latvia: Chaerophyllum aromaticum - native species, rather frequent in all regions in forests, parks and shrublands, C. aureum - anthropophyte, known only from one locality in Daugavpils city along the railway, C. bulbosum - anthropophyte, earlier grown as a root vegetable and now found rarely in parks, at roadsides, waste places, along fences and under canopy of trees close to human settlements, C. hirsutum - native species, known from several localities only in south-eastern part of Latvia, mostly in the Daugava valley - forested ravines, slopes of broad-leaved forests, and C. temulum - alien species, known only from few localities - waste places, railway sides and old manor parks in the whole territory of Latvia. The most striking results are related to the distribution of C. hirsutum in Latvia. The literature sources and herbarium material of Anthriscus nitida, previously known and collected in Latvia, after our critical revision are considered as Chaerophyllum hirsutum, whereas Anthriscus nitida at least in the Latvian flora has not been identified yet and has been removed from the flora lists by mistake.

Emergent plant communities of oxbow lakes in northeastern Alberta: salinity, water-level fluctuation, and succession

1984 ◽  
Vol 62 (2) ◽  
pp. 310-316 ◽  
Author(s):  
V. J. Lieffers
Keyword(s):  
Water Level ◽  
Detrended Correspondence Analysis ◽  
Open Water ◽  
Water Levels ◽  
Water Level Fluctuations ◽  
Individual Species ◽  
Acorus Calamus ◽  
Oxbow Lakes ◽  
Salinity Water ◽  
Northeastern Alberta

Emergent vegetation was sampled in 15 oxbow lakes in a 50-km segment of the Athabasca River in northeastern Alberta. Cover of individual species was visually assessed in plots at the outer, middle, and (or) inner edge of the emergent zone of each lake (n, 37 sample units). Detrended correspondence analysis showed two main axes of variation. The first axis related to salinity. Water conductivity ranged from 170 to 12200 μS cm−1 and community types ranged from freshwater fens to saline wetland communities dominated by Scolochloa festucacea, Scirpus maritimus, and Triglochin maritima. The second axis of variation related to water-level fluctuations. Half of the lakes had an increase in water level in the recent past (ca. 6–30 years). In these lakes, Typha latifolia was dominant in both grounded and floating substrates subjected to increased water levels. Sedge communities dominated by Carex rostrata, C. aquatilis, and Acorus calamus were common in sites with stable water levels. In freshwater lakes, floating substrates were established over open water by the lateral growth of floating stems of Calla palustris and Potentilla palustris. Floating substrates were not in the saline sites probably because these open-water colonizers were not present under saline regimes.

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