Fish of Trinity Inlet system of north Queensland with notes on the ecology of fish faunas of tropical Indo-Pacific estuaries

1980 ◽  
Vol 31 (2) ◽  
pp. 137 ◽  
Author(s):  
SJM Blaber
Keyword(s):  
Species Diversity ◽  
Marine Fish ◽  
Juvenile Fish ◽  
Open Water ◽  
Important Food ◽  
Inlet System ◽  
Tropical Estuaries ◽  
Calm Water ◽  
Benthic Animals ◽  
Trinity Bay

The fish faunas of tropical Trinity estuary and adjacent Trinity Bay are described. The fauna of the estuary is compared with that of other tropical Indo-Pacific estuaries and is found to be similar: all are dominated by juvenile marine fish. Numbers of planktivores are high and swimming prawns are an important food for many species. Absence of extensive shallow areas and a low biomass of benthic animals in Trinity estuary apparently limits the numbers of benthic feeding fish. Piscivores are few in the estuary and mainly represented by juveniles. Trinity Bay has fewer species represented by juveniles than the estuaries. higher numbers of piscivores, mainly adults, and fewer planktivores. The species diversity of Mugilidae in all areas is probably influenced by substrate diversity. Physical data indicate that substrate, turbidity and depth, together with relatively calm water in estuaries, affect the distribution ofjuvenile marine fish. If Trinity Bay is representative of areas of open water adjacent to tropical estuaries, the significantly lower numbers of piscivores in the estuaries may increase their advantage as sanctuaries for juvenile fish.

Optimization of RANS Solver Simulation Setup for Propeller Open Water Performance Prediction

2015 ◽  
Author(s):  
Mohammed Islam ◽  
Fatima Jahra ◽  
Michael Doucet
Keyword(s):  
Domain Size ◽  
Open Water ◽  
Fractional Factorial ◽  
Navier Stokes ◽  
Calm Water ◽  
Simulation Results ◽  
Open Water Performance ◽  
Thrust And Torque ◽  
Simulation Time ◽  
Fixed Pitch

Mesh and domain optimization strategies for a RANS solver to accurately estimate the open water propulsive characteristics of fixed pitch propellers are proposed based on examining the effect of different mesh and computation domain parameters. The optimized mesh and domain size parameters were selected using Design of Experiments (DoE) methods enabling simulations to be carried out in a limited memory environment, and in a timely manner; without compromising the accuracy of results. A Reynolds-Averaged Navier Stokes solver is used to predict the propulsive performance of a fixed pitch propeller. The predicted thrust and torque for the propeller were compared to the corresponding measurements. A total of six meshing parameters were selected that could affect the computational results of propeller open water performance. A two-level fractional factorial design was used to screen out parameters that do not significantly contribute to explaining the dependent parameters: namely simulation time, propeller thrust and propeller torque. A total of 32 simulations were carried out only to find out that the selected six meshing parameters were significant in defining the response parameters. Optimum values of each of the input parameters were obtained for the DOE technique and additional simulations were run with those parameters. The simulation results were validated using open water experimental results of the same propeller. It was found that with the optimized meshing arrangement, the propeller opens simulation time was reduced by at least a factor of 6 as compared to the generally popular meshing arrangement. Also, the accuracy of propulsive characteristics was improved by up to 50% as compared to published simulation results. The methodologies presented in this paper can be similarly applied to other simulations such as calm water ship resistance, ship propulsion to systematically derive the optimized meshing arrangement for simulations with minimal simulation time and maximum accuracy. This investigation was carried out using STAR-CCM+, a commercial CFD package; however the findings can be applied to any RANS solver.

scholarly journals Use of the flooded forest by fish assemblages in lakes of the National Park of Anavilhanas (Amazonas, Brazil)

2012 ◽  
Vol 42 (4) ◽  
pp. 561-566 ◽  
Author(s):  
Janette Noveras ◽  
Kedma C. Yamamoto ◽  
Carlos E.C. Freitas
Keyword(s):  
Species Diversity ◽  
Correspondence Analysis ◽  
National Park ◽  
Fish Assemblages ◽  
Open Water ◽  
Flooded Forest ◽  
Rio Negro ◽  
Flooded Forests ◽  
Filter Feeders ◽  
Distribution Of Fish

We evaluated diversity and distribution of fish species in two habitats: flooded forest and open water of lakes of Rio Negro. Each of four lakes within the Anavilhanas Archipelago was sampled three times from 2009-2010. Species diversity generally was higher in flooded forests and at night, according to correspondence analysis. Predators were most active at night, but showed no preference between the flooded forest and open water habitats. Omnivores, filter feeders, and detritivores were most active during the day.

Colonization by lake benthos of hard substrata in the water column versus on the bottom

1998 ◽  
Vol 49 (2) ◽  
pp. 157 ◽  
Author(s):  
G. P. Quinn ◽  
P. S. Lake ◽  
E. S. G. Schreiber
Keyword(s):  
Water Column ◽  
Benthic Macroinvertebrates ◽  
Open Water ◽  
Almost All ◽  
Benthic Animals ◽  
Hard Substrata

Little work has been done on colonization by lake benthos, particularly onto hard substrata. This study experimentally compared the rates of colonization of hard substrata (bricks) in a lake by benthic macroinvertebrates from two sources — the water column and the bottom. Colonization onto bricks (as mimics of stones) placed on the bottom of the lake was compared with colonization onto bricks suspended in the water column, where they could not be reached by crawling fauna. Almost all taxa colonizing bottom bricks also colonized suspended bricks, including taxa usually considered benthic (e.g. gastropods, mites, oligochaetes and planarians). Water-column samples confirmed the presence of these taxa in open water. These results suggest that many benthic animals in lakes may move through the water column more readily than previously considered; constant movement by lake benthos may be in response to shortage of resources.

scholarly journals Improving accuracy and efficiency of CFD predictions of propeller open water performance

2019 ◽  
Vol 16 (1) ◽  
pp. 1-20
Author(s):  
Mohammed Islam ◽  
Fatima Jahra
Keyword(s):  
Domain Size ◽  
Open Water ◽  
Navier Stokes ◽  
Calm Water ◽  
Open Water Performance ◽  
Improving Accuracy ◽  
Accuracy Of Results ◽  
Thrust And Torque ◽  
Simulation Time ◽  
Fixed Pitch

This research proposes mesh and domain optimization strategies for a popular Computational Fluid Dynamics (CFD) technique to estimate the open water propulsive characteristics of fixed pitch propellers accurately and time-efficiently based on examining the effect of various mesh and computation domain parameters. It used a Reynolds-Averaged Navier-Stokes (RANS) solver to predict the propulsive performance of a fixed pitch propeller with varied meshing, simulation domain and setup parameters. The optimized mesh and domain size parameters were selected using Design of Experiments (DoE) methods enabling simulations in a limited memory and in a timely manner without compromising the accuracy of results. The predicted thrust and torque for the propeller were compared to the corresponding measurements for determining the prediction accuracy. The authors found that the optimized meshing and setup arrangements reduced the propeller opens simulation time by at least a factor of six as compared to the generally popular CFD parameter setup. In addition, the accuracy of propulsive characteristics was improved by up to 50% as compared to published simulation results. The methodologies presented in this paper can be similarly applied to other simulations such as calm water ship resistance, ship propulsion etc. to systematically derive the optimized meshing arrangement for simulations with minimal simulation time and maximum accuracy. This investigation was carried out using a commercial CFD package; however, the findings can be applied to any RANS solver.

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.

Biological Conservation Implications of Water-level Fluctuations in a Wetland of International Importance: Lake Kerkini, Macedonia, Greece

1992 ◽  
Vol 19 (3) ◽  
pp. 235-244 ◽  
Author(s):  
Myrto Pyrovetsi ◽  
Evanthia Papastergiadou
Keyword(s):  
Species Diversity ◽  
Riparian Forest ◽  
Open Water ◽  
Water Level Fluctuations ◽  
Ramsar Convention ◽  
Wet Meadows ◽  
Water Storage Capacity ◽  
International Importance ◽  
Wetland Resources ◽  
Biotic Resources

Kerkini Lake in Greece, a reservoir maintained principally for agricultural irrigation purposes on the Strymon River, has been classified as a ‘Wetland of International Importance’ according to the Ramsar Convention. Hydrological conditions favoured the formation of a shallow, very productive lake, rich in species diversity and biotic abundance. The importance of the wetland lay in its complex zonation of various habitats which mainly consisted of: shallow open water with sand-strips, beaches, and mud-flats; shallow-water areas with communities of emergent vegetation; a lowland hardwood riparian forest mainly of Salix and Tamarix species; a shrub-swamp; and extensive wet meadows. The diversity of habitats supported a rich waterbird fauna for breeding, stationing during migration, and wintering.Nevertheless, in 1982 a new high-dam was constructed, higher embankments along the banks of the Lake were established, and other works were carried out (to increase the water capacity of the reservoir), in response to irrigation demands. No consideration was given to the wetland resources. Operation of the new dam resulted in changes in the flooding etc. regime, with severe impact on the biotic resources of the wetland, especially by waterlevel increases of more than 5 m in less than 4 months during spring — the critical growing- and breedingseason. Wetland heterogeneity and the mosaic structure of water-land-vegetation were thereby lost.Now the riparian forest is diminishing in area and declining in productivity, the reed-swamp with emergent macrophytes has been lost, and wet meadows have also disappeared. Deep flooding and the loss of these habitats is reflected in marked decline in the densities of migratory waterbird populations and, most important, in drastic shrinkage in the populations of breeding species. Similar impact is observed in the dramatic decline of fish species diversity and abundance. In general, nowadays, Kerkini presents an alarming example of loss of biodiversity and accelerating impoverishment of its former biotic resources.In view of the projected plans to increase further the water-storage capacity of the Lake by raising its waterlevel, measures are urgently needed: (a) for preventing such actions; (b) for restoring and maintaining marsh conditions, and (c) for ecologically sound management and sustainable use of the wetland resources.

scholarly journals Design of Propeller Series Optimizing Fuel Consumption and Propeller Efficiency

2021 ◽  
Vol 9 (11) ◽  
pp. 1226
Author(s):  
Mina Tadros ◽  
Manuel Ventura ◽  
Carlos Guedes Soares
Keyword(s):  
Fuel Consumption ◽  
Fitness Function ◽  
Open Water ◽  
Design Tool ◽  
Design Parameters ◽  
Propeller Design ◽  
Water Conditions ◽  
Calm Water ◽  
Propeller Performance ◽  
Propeller Geometry

This paper presents a comparison between different types of propellers operated in calm water to evaluate their performance behind hulls and in open-water conditions. A bulk carrier is chosen as a case study to perform the simulation and to evaluate the performance of several propeller series, namely the Wagengein B-series, Kaplan 19A, and MAU. Firstly, optimization procedures are performed by coupling a propeller design tool and a nonlinear optimizer to find the optimum design parameters of a fixed-pitch propeller. This optimization model aims to design the propeller behind the hull at the engine operating point with minimum fuel consumption and maximum propeller efficiency. The two main objectives of this study and the constraints are defined in a single fitness function to find the optimum values of the propeller geometry and the gearbox ratio. By considering the benefits of the single-objective over the multi-objective optimization problem, this model helps to find the optimum propeller for both defined objectives instead of only considering one of them, as in previous studies. Then, based on the optimized parameters, the propeller performance is calculated in open-water conditions. From the computed results, one can observe the importance of considering the hull–propulsor interaction in propeller selection.

THE MOVEMENT OF OIL SPILLS

1971 ◽  
Vol 1971 (1) ◽  
pp. 489-494 ◽  
Author(s):  
Henry G. Schwartzberg
Keyword(s):  
Wind Tunnel ◽  
Water Waves ◽  
Oil Spills ◽  
Wave Interaction ◽  
Open Water ◽  
Wind Drift ◽  
Calm Water ◽  
Waves And Currents ◽  
Infinite Height ◽  
Drift Analysis

ABSTRACT The effects of winds, waves, and currents, and the physical properties of oil and water on the drift rates of oil spills were studied in tests carried out in a combined water basin wind tunnel On calm water, oil drifted at a fairly constant percentage of the wind speed regardless of the nature and spreading tendencies of the oil, the spill size, and water temperature, depth, and salinity. Percent drift varied with wind tunnel height. Extrapolation to infinite height indicated that on calm open water wind drift should be 3.7%. Shallow water waves, which produced no significant drift themselves, reduced wind drift. Analysis indicated that deep water waves produced by the wind should produce significant drift, complicating wind drift prediction, but the magnitude of the wind wave interaction effects is not yet known. Test wind drifts and current drifts were found not to be directly additive.

scholarly journals The Diversity of Holothurioidea in the Intertidal Zone of the Pancur Shore of the Alas Purwo National Park

2015 ◽  
Vol 16 (1) ◽  
pp. 23 ◽  
Author(s):  
Riya Wulan Afrely ◽  
Moh. Imron Rosyidi ◽  
Susantin Fajariyah
Keyword(s):  
Species Diversity ◽  
Intertidal Zone ◽  
National Park ◽  
Sea Cucumber ◽  
Wave Motion ◽  
Diversity Index ◽  
Abiotic Factors ◽  
Species Diversity Index ◽  
Sea Cucumbers ◽  
Benthic Animals

Holothurioidea well known as Sea Cucumber is one of the classes from the Echinodermata phylum. Sea cucumbers are benthic animals that move slowly. Currently they already identified about 1135 species. Their existence usually associated with abiotic factors such as water salinity, temperature, pH, wave motion, light intensity and the substrate. The ability of the Holothurioidea to adapt to the abiotic factors will affect species diversity. The research aims is to determine the species diversity in the intertidal zone at Pancur Shore of the Alas Purwo National Park. It includes the species composition, species diversity index and the index of equality The study was conducted on 14th-21st of June 2014, by using systematic plotting transect method. The results found: one order, one family, two generas and eight species. The Species diversity index of Holothurioidea at Pancur Shore is low (0.930) and the equality index  classified uneven (0.447).Keywords: Holothurioidea, intertidal, diversity, evennes

Movements of juvenile barramundi, Lates calcarifer (Bloch), in north-eastern Queensland

1988 ◽  
Vol 39 (1) ◽  
pp. 117 ◽  
Author(s):  
DJ Russell ◽  
RN Garrett
Keyword(s):  
Average Distance ◽  
Juvenile Fish ◽  
Tidal Creeks ◽  
Lates Calcarifer ◽  
Coastal Habitats ◽  
Coastal Bays ◽  
North Eastern ◽  
Young Of The Year ◽  
Trinity Bay

Movements of juvenile barramundi resident in tidal creeks of two north-eastern Queensland coastal bays were determined using tag and recapture techniques. In a 3-year period from 1978, 1268 mainly young- of-the-year barramundi were tagged and 213 (17%) recaptured. Most fish were recaptured at the original tagging location, with only 32 (2.5% of all fish tagged) caught away from the tidal creeks where they were released. Marked fish continued to be recaptured within the tidal creeks until they were about 1 year old. Barramundi of this age moved out into the main estuary and dispersed into adjacent streams and coastal habitats. After leaving the tidal creeks, barramundi tagged in Trinity Bay moved an average distance of 7.6 km, whereas those tagged in Rockingham Bay moved an average of 23 km. Factors which may limit the movements of these juvenile fish are discussed.

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