Disentangling the multiple effects of stream drying and riparian canopy cover on the trophic ecology of a highly threatened fish

2020 ◽  
Vol 66 (1) ◽  
pp. 102-113
Author(s):  
Christopher G. Meijer ◽  
Helen J. Warburton ◽  
Angus R. McIntosh
Keyword(s):  
Trophic Ecology ◽  
Canopy Cover ◽  
Threatened Fish ◽  
Stream Drying ◽  
Riparian Canopy

scholarly journals Influence of Drying and Wildfire on Longitudinal Chemistry Patterns and Processes of Intermittent Streams

2020 ◽  
Vol 2 ◽  
Author(s):  
Ruth B. MacNeille ◽  
Kathleen A. Lohse ◽  
Sarah E. Godsey ◽  
Julia N. Perdrial ◽  
Colden V. Baxter
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Stream Water ◽  
Carbon Sources ◽  
Canopy Cover ◽  
Stream Chemistry ◽  
Intermittent Streams ◽  
Temporal Shift ◽  
Mean Values ◽  
Stream Drying ◽  
Patterns And Processes

Stream drying and wildfire are projected to increase with climate change in the western United States, and both are likely to impact stream chemistry patterns and processes. To investigate drying and wildfire effects on stream chemistry (carbon, nutrients, anions, cations, and isotopes), we examined seasonal drying in two intermittent streams in southwestern Idaho, one stream that was unburned and one that burned 8 months prior to our study period. During the seasonal recession following snowmelt, we hypothesized that spatiotemporal patterns of stream chemistry would change due to increased evaporation, groundwater dominance, and autochthonous carbon production. With increased nutrients and reduced canopy cover, we expected greater shifts in the burned stream. To capture spatial chemistry patterns, we sampled surface water for a suite of analytes along the length of each stream with a high spatial scope (50-m sampling along ~2,500 m). To capture temporal variation, we sampled each stream in April (higher flow), May, and June (lower flow) in 2016. Seasonal patterns and processes influencing stream chemistry were generally similar in both streams, but some were amplified in the burned stream. Mean dissolved inorganic carbon (DIC) concentrations increased with drying by 22% in the unburned and by 300% in the burned stream. In contrast, mean total nitrogen (TN) concentrations decreased in both streams, with a 16% TN decrease in the unburned stream and a 500% TN decrease (mostly nitrate) in the burned stream. Contrary to expectations, dissolved organic carbon (DOC) concentrations varied more in space than in time. In addition, we found the streams did not become more evaporative relative to the Local Meteoric Water Line (LMWL) and we found weak evidence for evapoconcentration with drying. However, consistent with our expectations, strontium-DIC ratios indicated stream water shifted toward groundwater-dominance, especially in the burned stream. Fluorescence and absorbance measurements showed considerable spatial variation in DOC sourcing each month in both streams, and mean values suggested a temporal shift from allochthonous toward autochthonous carbon sources in the burned stream. Our findings suggest that the effects of fire may magnify some chemistry patterns but not the biophysical controls that we tested with stream drying.

Experimental shading alters leaf litter breakdown in streams of contrasting riparian canopy cover

2011 ◽  
Vol 56 (10) ◽  
pp. 2059-2069 ◽  
Author(s):  
CLEMENT LAGRUE ◽  
JOHN S. KOMINOSKI ◽  
MICHAEL DANGER ◽  
JEAN-MARC BAUDOIN ◽  
SYLVAIN LAMOTHE ◽  
...  
Keyword(s):  
Leaf Litter ◽  
Canopy Cover ◽  
Litter Breakdown ◽  
Leaf Litter Breakdown ◽  
Riparian Canopy ◽  
Experimental Shading

scholarly journals Changes in Vegetation and Geomorphological Condition 10 Years after Riparian Restoration

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1252 ◽  
Author(s):  
William P. Higgisson ◽  
Paul O. Downey ◽  
Fiona J. Dyer
Keyword(s):  
Riparian Vegetation ◽  
Seedling Recruitment ◽  
Rapid Assessment ◽  
Canopy Cover ◽  
Aerial Imagery ◽  
Assessment Process ◽  
Riparian Restoration ◽  
Long Term Outcomes ◽  
Riparian Canopy

Riparian restoration is an important objective for landscape managers seeking to redress the widespread degradation of riparian areas and the ecosystem services they provide. This study investigated the long-term outcomes of ‘one-off’ restoration activities undertaken in the Upper Murrumbidgee Catchment, NSW, Australia. The objective of the restoration was to protect and enhance riparian vegetation and control erosion, and consequently reduce sediment and nutrient delivery into the Murrumbidgee River. To evaluate the outcomes 10 years after restoration, rapid riparian vegetation and geomorphological assessments were undertaken at 29 sites spanning the four different restoration methods used (at least five replicates per treatment), as well as at nine comparable untreated sites. We also trialed the use of aerial imagery to compare width of riparian canopy vegetation and projective foliage cover prior to restoration with that observed after 10 years. Aerial imagery demonstrated the width of riparian canopy vegetation and projective foliage cover increased in all restored sites, especially those with native plantings. The rapid assessment process indicated that 10 years after riparian restoration, the riparian vegetation was in a better condition at treated sites compared to untreated sites. Width of riparian canopy vegetation, native mid-storey cover, native canopy cover and seedling recruitment were significantly greater in treated sites compared to untreated sites. Geomorphological condition of treated sites was significantly better than untreated sites, demonstrating the importance of livestock exclusion to improve bank and channel condition. Our findings illustrate the value of ‘one-off’ restoration activities in achieving long-term benefits for riparian health. We have demonstrated that rapid assessments of the vegetation and geomorphological condition can be undertaken post-hoc to determine the long-term outcomes, especially when supported with analysis of historical aerial imagery.

Spatial assemblage structure of shallow-water reef fish in Southwest Australia

2020 ◽  
Vol 649 ◽  
pp. 125-140
Author(s):  
DS Goldsworthy ◽  
BJ Saunders ◽  
JRC Parker ◽  
ES Harvey
Keyword(s):  
Shallow Water ◽  
Reef Fish ◽  
Marine Environment ◽  
Fish Assemblages ◽  
Canopy Cover ◽  
Reef Fishes ◽  
Reef Fish Assemblage ◽  
Reef Type ◽  
Present Distribution ◽  
Southwest Australia

Bioregional categorisation of the Australian marine environment is essential to conserve and manage entire ecosystems, including the biota and associated habitats. It is important that these regions are optimally positioned to effectively plan for the protection of distinct assemblages. Recent climatic variation and changes to the marine environment in Southwest Australia (SWA) have resulted in shifts in species ranges and changes to the composition of marine assemblages. The goal of this study was to determine if the current bioregionalisation of SWA accurately represents the present distribution of shallow-water reef fishes across 2000 km of its subtropical and temperate coastline. Data was collected in 2015 using diver-operated underwater stereo-video surveys from 7 regions between Port Gregory (north of Geraldton) to the east of Esperance. This study indicated that (1) the shallow-water reef fish of SWA formed 4 distinct assemblages along the coast: one Midwestern, one Central and 2 Southern Assemblages; (2) differences between these fish assemblages were primarily driven by sea surface temperature, Ecklonia radiata cover, non-E. radiata (canopy) cover, understorey algae cover, reef type and reef height; and (3) each of the 4 assemblages were characterised by a high number of short-range Australian and Western Australian endemic species. The findings from this study suggest that 4, rather than the existing 3 bioregions would more effectively capture the shallow-water reef fish assemblage patterns, with boundaries having shifted southwards likely associated with ocean warming.

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