2020
Wang, Terrance; Kelson, Suzanne J.; Greer, George; Thompson, Sally E.; Carlson., Stephanie M.
Tributary confluences are dynamic thermal refuges for a juvenile salmonid in a warming river network Journal Article
In: River Research and Applications, 2020.
Abstract | Links | BibTeX | Tags: climate change, Eel river, ERCZO, microhabitat, Oncorhynchus mykiss, stream temperatures, thermal refuges, thermal tolerance
@article{Wang2020,
title = {Tributary confluences are dynamic thermal refuges for a juvenile salmonid in a warming river network},
author = {Terrance Wang and Suzanne J. Kelson and George Greer and Sally E. Thompson and Stephanie M. Carlson.},
doi = {10.1002/rra.3634},
year = {2020},
date = {2020-04-28},
journal = {River Research and Applications},
abstract = {As rivers warm, cold‐water fish species may alleviate thermal stress by moving into localized thermal refuges such as cold‐water plumes created by cool tributary inflows. We quantified use of two tributary confluence plumes by juvenile steelhead, Oncorhynchus mykiss , throughout the summer, including how trout positioned themselves in relation to temperature within confluence plumes. At two confluences, Cedar and Elder creeks, along the South Fork Eel River, California, USA, we monitored temperatures using in situ logger grids throughout summer 2016. Fish were counted within confluences via snorkel surveys five times a day on 5 days at each site. We found diel and seasonal dependence on confluence use by steelhead, especially at the Cedar Creek confluence, where mainstem temperatures exceeded 28°C. At this site, fish moved into the confluence on the warmest days and warmest times of the day. Fish observed within the Cedar Creek confluence plume were most common in locations between 20–22°C, rather than the coldest locations (14.5°C). At Elder Creek, where mainstem temperatures remained below 24°C, there was little relationship between mainstem temperature and steelhead presence in the confluence plume. At both sites, steelhead distribution within plumes was influenced by spatial variation of temperature and mean temperature in surveyed grid cells. Our results show that cool tributaries flowing into warmer mainstem reaches (over 24°C) likely create important thermal refuges for juvenile steelhead. As mainstem rivers warm with climate change, cool‐water tributary inputs may become more important for sustaining cold‐water salmonids near the southern end of their range.},
keywords = {climate change, Eel river, ERCZO, microhabitat, Oncorhynchus mykiss, stream temperatures, thermal refuges, thermal tolerance},
pubstate = {published},
tppubtype = {article}
}
As rivers warm, cold‐water fish species may alleviate thermal stress by moving into localized thermal refuges such as cold‐water plumes created by cool tributary inflows. We quantified use of two tributary confluence plumes by juvenile steelhead, Oncorhynchus mykiss , throughout the summer, including how trout positioned themselves in relation to temperature within confluence plumes. At two confluences, Cedar and Elder creeks, along the South Fork Eel River, California, USA, we monitored temperatures using in situ logger grids throughout summer 2016. Fish were counted within confluences via snorkel surveys five times a day on 5 days at each site. We found diel and seasonal dependence on confluence use by steelhead, especially at the Cedar Creek confluence, where mainstem temperatures exceeded 28°C. At this site, fish moved into the confluence on the warmest days and warmest times of the day. Fish observed within the Cedar Creek confluence plume were most common in locations between 20–22°C, rather than the coldest locations (14.5°C). At Elder Creek, where mainstem temperatures remained below 24°C, there was little relationship between mainstem temperature and steelhead presence in the confluence plume. At both sites, steelhead distribution within plumes was influenced by spatial variation of temperature and mean temperature in surveyed grid cells. Our results show that cool tributaries flowing into warmer mainstem reaches (over 24°C) likely create important thermal refuges for juvenile steelhead. As mainstem rivers warm with climate change, cool‐water tributary inputs may become more important for sustaining cold‐water salmonids near the southern end of their range.
2001
Gresens, SE
Thermal sensitivity of ingestion and digestion in larvae of a eurythermal chironomid Journal Article
In: Journal of the North American Benthological Society, vol. 20, iss. 1, pp. 68-83, 2001.
Abstract | Links | BibTeX | Tags: thermal tolerance
@article{Gresens2001,
title = {Thermal sensitivity of ingestion and digestion in larvae of a eurythermal chironomid},
author = {SE Gresens},
url = {http://www.jstor.org/stable/1468189},
doi = {10.2307/1468189},
year = {2001},
date = {2001-03-01},
urldate = {2001-03-01},
journal = {Journal of the North American Benthological Society},
volume = {20},
issue = {1},
pages = {68-83},
abstract = {Abstract In northern California rivers, rapid population growth of the chironomid Pseudochironomus richardsoni is associated with macroalgal blooms and with the warm temperatures and abundance of diatoms found in algal mats. Radioisotope techniques, including the dual-label method, were used to measure larval ingestion and digestion of diatoms in the laboratory. The epiphytic diatoms used in these studies had a low C:N ratio (6.4) and organic matter content (31%) compared to other potential food resources of larvae in nature. Mean individual ingestion rates increased 6-fold, from 0.0443 mg/d to 0.265 mg/d (dry mass), over a temperature range from 5° to 30°C. Ingestion increased most rapidly between 5° and 15°C but showed a weak relation to temperature from 15° to 30°C. In contrast to ingestion rate, absorption efficiency of larvae was independent of temperature over a 20°C range and averaged 32%. This result was surprising because absorption efficiency should decrease when gut passage time is reduced. These results suggest that there are compensatory changes in digestive processing (e.g., increased enzyme activity) that allow larvae to maintain constant absorption efficiency. This adaptation would benefit eurythermal consumers because the rate of absorption of energy and nutrients would also increase with temperature to help meet higher metabolic demands.},
keywords = {thermal tolerance},
pubstate = {published},
tppubtype = {article}
}
Abstract In northern California rivers, rapid population growth of the chironomid Pseudochironomus richardsoni is associated with macroalgal blooms and with the warm temperatures and abundance of diatoms found in algal mats. Radioisotope techniques, including the dual-label method, were used to measure larval ingestion and digestion of diatoms in the laboratory. The epiphytic diatoms used in these studies had a low C:N ratio (6.4) and organic matter content (31%) compared to other potential food resources of larvae in nature. Mean individual ingestion rates increased 6-fold, from 0.0443 mg/d to 0.265 mg/d (dry mass), over a temperature range from 5° to 30°C. Ingestion increased most rapidly between 5° and 15°C but showed a weak relation to temperature from 15° to 30°C. In contrast to ingestion rate, absorption efficiency of larvae was independent of temperature over a 20°C range and averaged 32%. This result was surprising because absorption efficiency should decrease when gut passage time is reduced. These results suggest that there are compensatory changes in digestive processing (e.g., increased enzyme activity) that allow larvae to maintain constant absorption efficiency. This adaptation would benefit eurythermal consumers because the rate of absorption of energy and nutrients would also increase with temperature to help meet higher metabolic demands.