Do Thermoclines Explain the Vertical Distributions of Larval Fishes in the Dynamic Coastal Waters of South-eastern Australia?

1996 ◽  
Vol 47 (2) ◽  
pp. 183 ◽  
Author(s):  
CA Gray
Keyword(s):  
Vertical Distribution ◽  
Coastal Waters ◽  
Spatial Scales ◽  
Major Influence ◽  
Larval Fishes ◽  
Larval Behaviour ◽  
Eastern Australia ◽  
Water Columns ◽  
Vertical Distributions ◽  
Deep Depth

This study examined whether the position and strength of the thermocline influenced the vertical distributions of larval fishes in the coastal waters off Sydney. Depth-stratified sampling of larval assemblages was done in stratified and non-stratified conditions. Larval assemblages were depth- stratified, and individual taxa displayed specific depth distributions in all types of water columns. In stratified and non-stratified water columns some species were characteristic of shallow, mid and deep depth strata. The presence of a thermocline did not appear to influence broad-scale patterns of vertical distribution of larval fishes, and it was not considered a good predictor of larval vertical distribution. Larval behaviour appeared to be the major influence determining vertical distributions of larval fishes. It is argued that thermoclines may not be important to larval fishes in waters characterized by dynamic oceanography, such as those off Sydney, where the position and integrity of the thermocline can vary greatly over small temporal and spatial scales. Greater emphasis needs to be placed on teasing out the importance of various interacting biotic and abiotic features of the water column in structuring vertical distributions of larval fishes.

Subtropical drosophilids in Australia can be characterized by adult distribution across vegetation type and by height above forest floor

2001 ◽  
Vol 17 (5) ◽  
pp. 705-718 ◽  
Author(s):  
RIEKS DEKKER VAN KLINKEN ◽  
G. H. WALTER
Keyword(s):  
Vertical Distribution ◽  
Forest Floor ◽  
Vegetation Type ◽  
Ground Level ◽  
Common Species ◽  
Vegetation Types ◽  
Eastern Australia ◽  
Vertical Distributions ◽  
Local Ecology ◽  
Open Woodland

Understanding the pattern in which adult drosophilids of different species are distributed across and within different vegetation types is necessary for accurate interpretation of their local ecology and diversity. Such studies have been conducted mainly in temperate regions, and there is no basis for extrapolating their conclusions to tropical areas. This study describes the vertical distribution (0-20 m) of drosophilids attracted to banana baits in five different vegetation types in subtropical eastern Australia including open woodland, and rain-forest types. The distribution of most of the 15 common species could be characterized three-dimensionally by vegetation type and height above forest floor. Only one species, Scaptodrosophila lativittata, was common in all vegetation types and it was a canopy species in rain forests and a ground-level species in open woodland. Vertical distribution of some species clearly matched that of their larval hosts, but it did not in others. For example, the fungivore Leucophenga scutellata was mostly trapped well above the forest floor, yet it breeds at ground level, suggesting behavioural mode can influence vertical distributions. We conclude that the vertical dimension, although still poorly understood in relation to drosophilid habitats, needs to be taken into account when conducting and interpreting studies aimed at understanding drosophilid populations and communities in the subtropics.

scholarly journals Using acoustic technology to improve the modelling of the transportation and distribution of juvenile gadoids in the Barents Sea

2009 ◽  
Vol 66 (6) ◽  
pp. 1048-1054 ◽  
Author(s):  
Geir O. Johansen ◽  
Olav R. Godø ◽  
Morten D. Skogen ◽  
Terje Torkelsen
Keyword(s):  
Vertical Distribution ◽  
Conceptual Model ◽  
Prediction Models ◽  
Barents Sea ◽  
Transport Model ◽  
Spatial Scales ◽  
Growth And Survival ◽  
The Barents Sea ◽  
Vertical Distributions ◽  
Tracking Model

Abstract Johansen, G. O., Godø, O. R., Skogen, M. D., and Torkelsen, T. 2009. Using acoustic technology to improve the modelling of the transportation and distribution of juvenile gadoids in the Barents Sea. – ICES Journal of Marine Science, 66: 1048–1054. Transport of the juvenile stages of gadoids by oceanic currents in the Barents Sea is governed by interactions between the vertical positioning of the fish and the horizontal movement of the water masses. The resulting geographical distribution is important for growth and survival. There is need for observations at proper temporal and spatial scales to improve the representation of vertical distribution in models of the transport process. Stationary acoustic systems are suitable for this purpose. We use such a system to quantify the vertical dynamics of 0-group gadoids with reference to a conceptual model of the temporal variation. The vertical distribution from the conceptual model is applied within a Lagrangian, particle-tracking model. This approach performs better in predicting the geographic distribution of the 0-group during the first 10 months after hatching than a model with random, vertical distribution. The potential of stationary acoustic systems to provide high-quality vertical distributions that improve the predictive power of the transport model is demonstrated. Extensive sampling programmes based on the principles presented here can provide the observations needed to obtain more realistic recruitment–prediction models.

WAVE CLIMATE OF THE BLACK SEA’S COASTAL WATERS DURING THE LAST THREE DECADES

2017 ◽  
Author(s):  
Fedor Gippius ◽  
Fedor Gippius ◽  
Stanislav Myslenkov ◽  
Stanislav Myslenkov ◽  
Elena Stoliarova ◽  
...  
Keyword(s):  
Wind Speed ◽  
Cell Size ◽  
Coastal Waters ◽  
Wind Wave ◽  
Spatial Scales ◽  
Wave Model ◽  
Wave Climate ◽  
Computational Grid ◽  
Coastal Areas ◽  
Wave Parameters

This study is focused on the alterations and typical features of the wind wave climate of the Black Sea’s coastal waters since 1979 till nowadays. Wind wave parameters were calculated by means of the 3rd-generation numerical spectral wind wave model SWAN, which is widely used on various spatial scales – both coastal waters and open seas. Data on wind speed and direction from the NCEP CFSR reanalysis were used as forcing. The computations were performed on an unstructured computational grid with cell size depending on the distance from the shoreline. Modeling results were applied to evaluate the main characteristics of the wind wave in various coastal areas of the sea.

scholarly journals On the generation of internal waves by river plumes in subcritical initial conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Mendes ◽  
J. C. B. da Silva ◽  
J. M. Magalhaes ◽  
B. St-Denis ◽  
D. Bourgault ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Internal Waves ◽  
Coastal Waters ◽  
Initial Conditions ◽  
Spatial Scales ◽  
River Plumes ◽  
Wide Range ◽  
Near Shore ◽  
Generation Mechanisms ◽  
Douro River

AbstractInternal waves (IWs) in the ocean span across a wide range of time and spatial scales and are now acknowledged as important sources of turbulence and mixing, with the largest observations having 200 m in amplitude and vertical velocities close to 0.5 m s−1. Their origin is mostly tidal, but an increasing number of non-tidal generation mechanisms have also been observed. For instance, river plumes provide horizontally propagating density fronts, which were observed to generate IWs when transitioning from supercritical to subcritical flow. In this study, satellite imagery and autonomous underwater measurements are combined with numerical modeling to investigate IW generation from an initial subcritical density front originating at the Douro River plume (western Iberian coast). These unprecedented results may have important implications in near-shore dynamics since that suggest that rivers of moderate flow may play an important role in IW generation between fresh riverine and coastal waters.

scholarly journals Perspectives on Larval Behaviour in Biophysical Modelling of Larval Dispersal in Marine, Demersal Fishes

Oceans ◽  
2020 ◽  
Vol 2 (1) ◽  
pp. 1-25
Author(s):  
Jeffrey M. Leis
Keyword(s):  
Fish Larvae ◽  
Behavioural Change ◽  
Larval Fishes ◽  
Larval Behaviour ◽  
Key Issues ◽  
Modelling Effort ◽  
Validation Research ◽  
Vertical Positioning ◽  
Study Species ◽  
Demersal Fishes

Biophysical dispersal models for marine fish larvae are widely used by marine ecologists and managers of fisheries and marine protected areas to predict movement of larval fishes during their pelagic larval duration (PLD). Over the past 25 years, it has become obvious that behaviour—primarily vertical positioning, horizontal swimming and orientation—of larvae during their PLD can strongly influence dispersal outcomes. Yet, most published models do not include even one of these behaviours, and only a tiny fraction include all three. Furthermore, there is no clarity on how behaviours should be incorporated into models, nor on how to obtain the quantitative, empirical data needed to parameterize models. The PLD is a period of morphological, physiological and behavioural change, which presents challenges for modelling. The present paper aims to encourage the inclusion of larval behaviour in biophysical dispersal models for larvae of marine demersal fishes by providing practical suggestions, advice and insights about obtaining and incorporating behaviour of larval fishes into such models based on experience. Key issues are features of different behavioural metrics, incorporation of ontogenetic, temporal, spatial and among-individual variation, and model validation. Research on behaviour of larvae of study species should be part of any modelling effort.

scholarly journals Uterine fluid composition of the dwarf ornate wobbegong shark (Orectolobus ornatus) during gestation

2011 ◽  
Vol 62 (6) ◽  
pp. 576 ◽  
Author(s):  
Megan T. Ellis ◽  
Nicholas M. Otway
Keyword(s):  
Reproductive Biology ◽  
Coastal Waters ◽  
Reproductive Strategies ◽  
Yolk Sac ◽  
Gestation Period ◽  
Fluid Composition ◽  
Complex Composition ◽  
Eastern Australia ◽  
Uterine Fluid ◽  
Low Levels

Low fecundity in chondrichthyans makes them extremely susceptible to fishing, so understanding the various reproductive strategies in this group is vital for management. Knowledge of the uterine fluid (UF) composition throughout gestation is fundamental to this understanding, yet is restricted to a few species. This study focussed on the UF composition of the wobbegong (Orectolobus ornatus), which inhabits coastal waters off eastern Australia. The UF was quantified throughout pregnancy. Fluids surrounding uterine eggs had a complex composition, with mean urea (98.48 mmol L–1), sodium (560.25 mmol L–1) and potassium (13.93 mmol L–1) concentrations significantly greater than those in seawater. A change in composition, from complex to simple, occurred after 3–4 months gestation. Major electrolyte concentrations then resembled seawater for the remainder of gestation, suggesting the flushing of the uteri with seawater and evidenced by fluctuating low levels of urea. The gestation period reflected the time for metabolism of yolk stores, osmotic and ionic adjustment, development of functioning immunological systems and prevention of external yolk sac damage. Our study is the first documentation of UF composition for a wobbegong shark and increases understanding of its reproductive biology.

scholarly journals Observations of the summertime atmospheric pollutants vertical distributions and the corresponding ozone production in Shanghai, China

2017 ◽  
Author(s):  
Chengzhi Xing ◽  
Cheng Liu ◽  
Shanshan Wang ◽  
Ka Lok Chan ◽  
Yang Gao ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Pearson Correlation ◽  
A Priori ◽  
Lower Troposphere ◽  
Sensitivity Study ◽  
Atmospheric Pollutants ◽  
Ozone Production ◽  
Optical Absorption Spectroscopy ◽  
Lidar Measurements ◽  
Vertical Distributions

Abstract. Ground based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) and lidar measurements were performed in Shanghai, China during May 2016 to investigate the summertime atmospheric pollutants vertical distribution. In this study, vertical profiles of aerosol extinction coefficient, nitrogen dioxide (NO2) and formaldehyde (HCHO) concentrations were retrieved from MAX-DOAS measurement using the Heidelberg Profile (HeiPro) algorithm, while vertical distribution of ozone (O3) was obtained from an ozone lidar. Sensitivity study of the MAX-DOAS aerosol profile retrieval shows that the a priori aerosol profile shape has significant influences on the aerosol profile retrieval. Aerosol profiles retrieved from MAX-DOAS measurements with Gaussian a priori demonstrate the best agreements with simultaneous lidar measurements and vehicle-based tethered-balloon observations among all a priori aerosol profiles. MAX-DOAS measured tropospheric NO2Vertical Column Densities (VCDs) show a good agreement with OMI satellite observations with Pearson correlation coefficient (R) of 0.95. In addition, measurements of the O3 vertical distribution indicate that the ozone productions do not only occur at surface level but also at higher altitudes (about 1.1 km). Planetary boundary layer (PBL) height, horizontal and vertical wind fields information were integrated to discuss the ozone formation at upper altitudes. The results reveal that enhanced ozone concentrations at ground and upper altitudes are not directly related to horizontal and vertical transportations. Similar patterns of O3 and HCHO vertical distributions were observed during this campaign, which implies that the ozone productions near to the surface and at higher altitudes are mainly influenced by the abundance of volatile organic compounds (VOCs) in the lower troposphere.

A global approach to hierarchical classification of coastal waters at different spatial scales: the NEA case

2016 ◽  
Vol 97 (3) ◽  
pp. 465-476 ◽  
Author(s):  
José A. Juanes ◽  
Araceli Puente ◽  
Elvira Ramos
Keyword(s):  
Coastal Waters ◽  
Spatial Scales ◽  
Atlantic Coast ◽  
Coastal Areas ◽  
Biological Information ◽  
Management Tool ◽  
Global Approach ◽  
Ne Atlantic ◽  
Wide Range

Ecological classification of coastal waters has become increasingly important as one of the basic issues in the biology of conservation. Management and protection of coastal areas take place at different spatial scales. Thus, proper classification schemes should integrate equivalent information at various levels of definition in order to show its feasibility as a useful tool for assessment of coastal environments at the required scales. In this work, a global approach applied to the classification of the NE Atlantic coast is analysed in order to discuss pros and cons regarding different conceptual and technical issues for effective implementation of such a management tool. Using the hierarchical system applied at three different geographic scales: Biogeographic (NE Atlantic coast), Regional (Bay of Biscay) and Local (Cantabria region), five different topics were considered for debating strengths and weaknesses of the methodological alternatives at those spatial scales, using for validation the rocky shore macroalgae as a representative biological element of benthic communities. These included: (i) the spatial scales; (ii) the physical variables and indicators; (iii) the classification methodologies; (iv) the biological information; and (v) the validation procedure. Based on that analysis, the hierarchical support system summarized in this paper provides a management framework for classification of coastal systems at the most appropriate resolution, applicable to a wide range of coastal areas. Further applications of the physical classification for management of biodiversity in different environmental scenarios are also analysed.

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