Experimental Rehabilitation of Degraded Spawning Habitat of a Diadromous Fish,Galaxias maculatus(Jenyns, 1842) in Rural and Urban Streams

2014 ◽  
Vol 22 (3) ◽  
pp. 319-326 ◽  
Author(s):  
Michael J. H. Hickford ◽  
David R. Schiel
2010 ◽  
Vol 61 (11) ◽  
pp. 1252 ◽  
Author(s):  
Andy Hicks ◽  
Nicole C. Barbee ◽  
Stephen E. Swearer ◽  
Barbara J. Downes

In habitats such as estuaries, which are characterised by large and fluctuating gradients in abiotic variables, finding appropriate habitat for successful spawning and egg development can be critical to a species’ survival. We explored how salinity requirements for successful fertilisation may govern the distribution of estuarine spawning habitat for the diadromous fish, Galaxias maculatus, which spawns in inundated vegetation on estuary banks during spring tides. Artificial fertilisation experiments confirmed that successful fertilisation only occurs at low salinities (<20). Thus, we predicted that egg distributions would depend upon the extent of low-salinity surface waters in an estuary. Using estuary geomorphology classification schemes, which classify estuaries by physical and chemical characteristics such as their salinity dynamics, we hypothesised that stratified estuaries would provide a greater extent of low salinity surface water than well-mixed estuaries. This prediction was supported by surveys of egg distributions in five estuaries in Victoria, Australia. Eggs were distributed over a greater proportion of ‘stratified’ v. ‘mixed’ estuary types. We suggest that combining knowledge of the spawning requirements of a species and physical properties of the habitat, such as those encapsulated in estuary geomorphic classification schemes, can greatly facilitate efforts to identify critical habitats and thus aid in species management and conservation.


2016 ◽  
Vol 35 (9) ◽  
pp. 2209-2214 ◽  
Author(s):  
Oliver R.B. Thomas ◽  
Nicole C. Barbee ◽  
Kathryn L. Hassell ◽  
Stephen E. Swearer

2018 ◽  
Vol 16 (1) ◽  
Author(s):  
Jardel Nimet ◽  
João Paulo de Arruda Amorim ◽  
Rosilene Luciana Delariva

ABSTRACT This study evaluated gills and liver of Astyanax bifasciatus as histological biomarkers for biomonitoring of streams along areas with different land uses. The fish were collected by electrofishing in six streams in the basin of the lower Iguaçu River. The objective was to correlate the presence and degree of histopathological alterations of gills and liver with the environmental variables among streams along different land uses. The low frequency of histopathological alterations found in fish from the forest streams suggested normal organ functioning. In fish from the rural and urban streams, the histopathological alterations occurred were in higher frequency, indicated light to moderate damage in gills and liver of fish from the rural streams, and moderate to severe damage in liver of fish from urban streams. The histopathological alterations in gills (lamellar aneurysm) and livers (vascular congestion) verified in impacted streams were significantly more frequent and severe. It was possible to distinguish streams along different land uses, suggesting that these histopathological alterations can be used as biomarkers for biomonitoring studies. The health integrity of fish from streams in forest areas further reinforces the importance of maintaining preservation areas in basins under intensive land use.


2010 ◽  
Vol 95 (3) ◽  
pp. 260-272 ◽  
Author(s):  
Adelina Maria Kühl ◽  
Carmen Lúcia Mello Sartori Cardoso da Rocha ◽  
Evaldo Luiz Gaeta Espíndola ◽  
Fábio Amodêo Lansac-Tôha

Author(s):  
Luiz Felipe Machado Velho ◽  
Suzana de Fátima Rodrigues de Castro ◽  
Fernando Miranda Lansac-Tôha ◽  
Bianca Ramos Meira ◽  
Felipe Rafael de Oliveira ◽  
...  

The aim of this study was to investigate the spatial and temporal patterns in species composition of ciliates, in rural streams, affected by agricultural activities, and urban streams, impacted by domestic wastewater. Samplings were taken in two different periods of the year, in the headwater, middle and mouth stretch of ten streams. We recorded 143 species of ciliates, distributed in 14 groups, standing out Hymenostomatia, Peritrichia and Hypotrichia. Our results showed significant spatial (between rural and urban streams) and, especially, temporal differences (between winter and summer periods) in the ciliates taxonomic composition. Such differences seem to be not related to the organic load that was quite similar among streams and periods sampled. Rather, the changes in ciliates composition are probably driving mainly by other enviromental variables such as resources, determined by the spatial diferences in light availability, and flow water velocity and discharge, which present high temporal dissimilarity.


2018 ◽  
Author(s):  
Shane Orchard ◽  
Michael J. H. Hickford

AbstractWe studied the effectiveness of conservation planning methods for Galaxias maculatus, a riparian spawning fish, following earthquake-induced habitat shift in the Canterbury region of New Zealand. Mapping and GIS overlay techniques were used to evaluate three protection mechanisms in operative or proposed plans in two study catchments over two years. Method 1 utilised a network of small protected areas around known spawning sites. It was the least resilient to change with only 3.9% of post-quake habitat remaining protected in the worst performing scenario. Method 2, based on mapped reaches of potential habitat, remained effective in one catchment (98%) but not in the other (52.5%). Method 3, based on a habitat model, achieved near 100% protection in both catchments but used planning areas far larger than the area of habitat actually used. This example illustrates resilience considerations for protected area design. Redundancy can help maintain effectiveness in face of dynamics and may be a pragmatic choice if planning area boundaries lack in-built adaptive capacity or require lengthy processes for amendment. However, an adaptive planning area coupled with monitoring offers high effectiveness from a smaller protected area. Incorporating elements of both strategies provides a promising conceptual basis for adaptation to major perturbations or responding to slow change.


2008 ◽  
Vol 59 (6) ◽  
pp. 467 ◽  
Author(s):  
Travis S. Elsdon ◽  
Karin E. Limburg

Although it is well known that land use affects nutrient dynamics and algal growth in streams, the responses to different durations of nutrient supply are poorly understood. The associations of benthic (periphyton-dominated) biomass with concentrations of dissolved nitrogen and phosphorus in rural and urban streams in New York were quantified. Biomass was significantly greater (2-fold) in the urban compared with the rural stream, which was associated with differences in dissolved nutrients. Experimental field enrichment of nutrient concentrations and duration of exposure altered benthic periphyton. Increasing nutrients by 60–99% of ambient concentrations increased periphyton percentage cover and biomass. Periphyton abundance also increased with increasing duration of exposure to nutrients (2, 4 and 8 weeks); however, short-term pulses of nutrients (2 weeks) had no significant effect in the rural stream. These results indicate that effective management of nutrient delivery, by reducing time periods of high nutrient load, will minimise impacts to benthic environments.


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