The distribution of four Chaoborus species (Diptera: Chaoboridae) along an elevation gradient in Canadian Rocky Mountain lakes

1994 ◽  
Vol 72 (9) ◽  
pp. 1531-1537 ◽  
Author(s):  
S. Lamontagne ◽  
D. B. Donald ◽  
D.W. Schindler

We tested the hypothesis that the distribution of four species of Chaoborus is limited by water temperature in Rocky Mountain lakes. Midsummer surface water temperature (MSSWT) of Rocky Mountain lakes varied between 25 and 5 °C along an elevation gradient spanning 600–2400 m above sea level. Chaoborus (subgenus Chaoborus) americanus and C. (C.) flavicans were collected in lakes with MSSWT ≥ 16 °C, generally corresponding to lakes at elevations lower than 1600 m above sea level. Chaoborus (Sayomyia) punctipennis was only collected in warm lakes (MSSWT ≥ 21 °C). Species of the subgenus Schadonophasma (C. trivittatus and possibly C. cooki) were not commonly collected, but preliminary data suggest that they may be more tolerant of low water temperatures than the other species. On a qualitative basis, the distribution of these chaoborids in the Rockies is similar to their latitudinal distribution. However, MSSWT as a valid predictor of Chaoborus species distribution with latitude remains to be tested. The gradient in lake temperature found in mountainous environments appears to be a useful gauge for obtaining information about the distribution of invertebrates relative to temperature.

2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Danielle R. Haskett Jennings

AbstractThe aim of this study was to determine which environmental variables are responsible for modern benthic chironomid distributions in a glacial setting. The chironomid communities from nine alpine lakes were assessed, and forty-three individual taxa were extracted and identified. Surface water temperature and nitrate were strongly and negatively correlated (−0.82, p = 0.007), suggesting that glacial meltwater (the driver that explains both surface water temperature (SWT) (°C) and nitrate (NO3 + NO2-N)) is the environmental variable that explains the most variance (15%). On average, lakes receiving glacial meltwater were 2.62 °C colder and contained 66% more NO3 + NO2-N than lakes only receiving meltwater from snow. The presence of taxa from the tribe Diamesinae indicates very cold input from running water, and these taxa may be used as a qualitative indicator species for the existence of glacial meltwater within a lake catchment. Heterotrissocladius, Diamesa spp., and Pseudodiamesa were present in the coldest lakes. Chironomus, Diplocladius, and Protanypus were assemblages found in cold lakes affiliated with the littoral zone or alpine streams. The modern benthic chironomid communities collected from the alpine of subalpine lakes of Rocky Mountain National Park, Colorado, represent a range of climatic and trophic influences and capture the transition from cold oligotrophic lakes to warmer and eutrophic conditions.


Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1109
Author(s):  
Nobuaki Kimura ◽  
Kei Ishida ◽  
Daichi Baba

Long-term climate change may strongly affect the aquatic environment in mid-latitude water resources. In particular, it can be demonstrated that temporal variations in surface water temperature in a reservoir have strong responses to air temperature. We adopted deep neural networks (DNNs) to understand the long-term relationships between air temperature and surface water temperature, because DNNs can easily deal with nonlinear data, including uncertainties, that are obtained in complicated climate and aquatic systems. In general, DNNs cannot appropriately predict unexperienced data (i.e., out-of-range training data), such as future water temperature. To improve this limitation, our idea is to introduce a transfer learning (TL) approach. The observed data were used to train a DNN-based model. Continuous data (i.e., air temperature) ranging over 150 years to pre-training to climate change, which were obtained from climate models and include a downscaling model, were used to predict past and future surface water temperatures in the reservoir. The results showed that the DNN-based model with the TL approach was able to approximately predict based on the difference between past and future air temperatures. The model suggested that the occurrences in the highest water temperature increased, and the occurrences in the lowest water temperature decreased in the future predictions.


2021 ◽  
Author(s):  
Zongqi Peng ◽  
Jiaying Yang ◽  
Yi Luo ◽  
Kun Yang ◽  
Chunxue Shang

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 521
Author(s):  
Caroline Martin ◽  
Stephanie K. Kampf ◽  
John C. Hammond ◽  
Codie Wilson ◽  
Suzanne P. Anderson

Developing accurate stream maps requires both an improved understanding of the drivers of streamflow spatial patterns and field verification. This study examined streamflow locations in three semiarid catchments across an elevation gradient in the Colorado Front Range, USA. The locations of surface flow throughout each channel network were mapped in the field and used to compute active drainage densities. Field surveys of active flow were compared to National Hydrography Dataset High Resolution (NHD HR) flowlines, digital topographic data, and geologic maps. The length of active flow declined with stream discharge in each of the catchments, with the greatest decline in the driest catchment. Of the tributaries that did not dry completely, 60% had stable flow heads and the remaining tributaries had flow heads that moved downstream with drying. The flow heads were initiated at mean contributing areas of 0.1 km2 at the lowest elevation catchment and 0.5 km2 at the highest elevation catchment, leading to active drainage densities that declined with elevation and snow persistence. The field mapped drainage densities were less than half the drainage densities that were represented using NHD HR. Geologic structures influenced the flow locations, with multiple flow heads initiated along faults and some tributaries following either fault lines or lithologic contacts.


Diversity ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 243
Author(s):  
Javier Alcocer ◽  
Luis A. Oseguera ◽  
Diana Ibarra-Morales ◽  
Elva Escobar ◽  
Lucero García-Cid

High-mountain lakes are among the most comparable ecosystems globally and recognized sentinels of global change. The present study pursued to identify how the benthic macroinvertebrates (BMI) communities of two tropical, high mountain lakes, El Sol and La Luna, Central Mexico, have been affected by global/regional environmental pressures. We compared the environmental characteristics and the BMI communities between 2000–2001 and 2017–2018. We identified three principal environmental changes (the air and water temperature increased, the lakes’ water level declined, and the pH augmented and became more variable), and four principal ecological changes in the BMI communities [a species richness reduction (7 to 4), a composition change, and a dominant species replacement all of them in Lake El Sol, a species richness increase (2 to 4) in Lake La Luna, and a drastic reduction in density (38% and 90%) and biomass (92%) in both lakes]. The air and water temperature increased 0.5 °C, and lakes water level declined 1.5 m, all suggesting an outcome of climate change. Contrarily to the expected acidification associated with acid precipitation, both lakes deacidified, and the annual pH fluctuation augmented. The causes of the deacidification and the deleterious impacts on the BMI communities remained to be identified.


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