FLORA AND FAUNA
Red Glasswort, Salicornia rubra
photo by Biology 375 class, UBC Okanagan, 2019
S. rubra is one of the most halotolerant plants in North America, correspondingly it has a widespread occurrence and goes by many common names. Found along the edges of Robert Lake it glows bright red when the stems are mature.
iNaturalists bioinventory project
Click on this link to see what flora and fauna have been found in and around the lake and to find out how to add to this inventory.
The more the special nature of Robert Lake is documented, the harder it will be to ignore its degradation.
Great Basin spadefoot are a provincially blue-listed species, meaning they are of Special Concern because populations are considered vulnerable to extinction or extirpation. Robert Lake and UBC Okanagan have been identified as critical ‘core’ and 'connectivity' habitat for these toads. Fragmentation of critical habitat and migration corridors can occur due to urbanization and road building. Even with the inclusion of wildlife culverts, the construction of John Hindle Drive has potentially compromised habitat connectivity in the Robert Lake area, and toad mortalities have been noted along the roadway. The consulting firm 'Associated Environmental' was retained by the City of Kelowna to look at the efficacy of the amphibian exclusion fencing along sections of John Hindle Drive and culverts for diverting spadefoots from the roadway itself.
The report concluded that, "based on the number of amphibian mortalities collected in 2021, the amphibian exclusion fencing does not indicate efficacy." Until gaps in the amphibian exclusion fencing can be filled and guards at the farming access gates are installed, it is expected that mortality will continue and the population numbers of spadefoot in this area will decline.
Monitoring is ongoing in 2022. Amongst other issues, the culverts are not proper wildlife culverts and they are thought to have insufficient bottom substrate to be attractive to amphibians, and they are too small for larger vertebrates (such as a badger) to use. It was planned that wildlife cameras would be installed to attempt to verify usage but the supply of these cameras from government agencies fell through.
Click the button on the side to see the complete report from Associated Environmental (updated link, if you tried this before).
Great Basin Spadefoot
photo from Creative Commons
American Avocets
American Avocets are also blue-listed in BC. They have been spotted in at least twenty sites in BC, and are often associated with alkaline lakes; however, breeding has only been documented at seven sites, one permanent location and six ephemeral locations. Alki Lake, now the site of the City of Kelowna landfill, is the only nesting site that is recorded as being used year after year. This site has been largely subsumed by the landfill, putting pressure on the birds to use Robert Lake, in which the birds have been observed to breed only once or twice before. Robert Lake is an important feeding ground for the species due to the high densities of chironomids, microcrustaceans and brine flies on which the birds feed. However, any nesting success would rely on water levels that allow for breeding 'islands' to exist and deter terrestrial predators, but with water levels not so high as to swamp the islands.
The plight of the American Avocet in BC has been an object of much discussion, along with the need to try and protect more habitat and enhance nesting opportunities Click the following two buttons to access more information on the topic.
Foraging American Avocet photo by Robert Lalonde
The American Badger is a red listed species in BC, meaning that their populations are critically imperiled. Although there is no badger currently living in the immediate area of Robert Lake, their dens are located on the nearby University lands. As medium sized carnivores they need to range widely over suitable habitat in order to meet their dietary needs. Recently, three were found as roadkill on Hwy. 97 and it was feared that they have been extirpated from the area. However, new dens have now been spotted in the region. Badgers are known to be particularly susceptible to roadkill, so John Hindle Drive and Academy Way put these animals in more peril than in previous years.
photo from Creative Commons
Badgers
photo from Creative Commons
Alkali Saltgrass-Foxtail Barley
photos from Creative Commons
The BC Conservation Data Centre makes reference to 'ecosystems at risk' but uses specific plant community associations as proxies for specific ecosystems. Alkali saltgrass-foxtail barley communities are indicators of seasonally flooded alkaline meadows found around saline lakes. The community is dominated by alkali saltgrass-foxtail barley but there is a large variety of other associated plant species present, including red glasswort. This community is red-listed in B.C. (B.C. Ministry of the Environment, IWMS document), which is indicative of the risk factor for the saline-alkaline ecosystem itself.
MICROORGANISMS
Too small to see but nevertheless they are critical to the functioning of the aquatic community in Robert Lake
Photosynthetic algae and bacteria, heterotrophic bacteria, and microscopic grazers and predators such as rotifers, cladocerans, copepods, and midge larvae are all components of a food web that connects to larger organisms like waterfowl. The food web transfers energy and nutrients through the community.
Like larger organisms, the community of microorganisms in Robert Lake exhibits seasonality in composition and abundance.
The seasonal cycle of zooplankton and microalgae in Robert Lake 2019 based on microscopy and metagenomic sampling. Taxonomic groups written in green with a + beside them are increasing in abundance and groups written in red with a - beside them are decreasing in abundance. Data for January to April are not missing, there was virtually nothing present in the samples.
Seasonal changes in light intensity and temperature affect microalgal populations and those that feed on the algae. However, there may also be a story of predatory-prey dynamics similar to that seen with macroscopic flora and fauna. Prey (microalgae such as diatoms, Trebouxiophyceae and cyanobacteria) increase in population size as the season moves into the warmer, more sunlit spring. This increase is followed by a rise in the population size of predators (microcrustaceans such as copepods and Daphnia, rotifers and some insect larvae) in June and July. Around late July-early August, a decrease in prey numbers occurs due to high rates of predation, but this results in a lack of food for predators and their numbers then decrease. With predation pressure lessened, some of the more cold tolerant algae rebound in abundance.
The algal genus Coccomyxa from Class Trebouxiophyceae was forming autospores in June and July concurrent with the decrease in regular, vegetative cells. Autospore formation in this taxon occurs in the presence of unfavorable conditions. Unfavourable conditions can include high densities of predators as well as high water temperatures.
Copepods produce a type of egg that rests in the mud until times are good for hatching. This explains the copepod nauplii (baby copepods) found in May. After which, the females produce a different type of egg that matures very quickly. In the late spring and summer, the reproductive cycle is around seven days. This explains the presence of copepod nauplii and egg carrying females in June.
The decrease in diatoms in August may be due to high temperatures, but also may be due to selective grazing by Daphnia. Daphnia have been shown to specifically target diatoms over other microalgae to obtain the high levels of long chain polyunsaturated fatty acids.
From: Butt S. 2021. Microscopic evaluation and 16SDNA primer efficacy in determining autotrophic microbiota community composition in a brackish, inland water body. Honours Thesis. UBC Okanagan. 45pp.
Dilution of lake waters appears to have caused a change in the microbiotic community.
This type of plot is called a heatmap. It shows the relative abundance of key taxonomic groups of microbes found in the high salinity conditions that occurred in Robert Lake during June 2015 (duplicate samples) and August 2016 compared to the lower salinity conditions that occurred in June 2018 and June and August 2019. Communities consist of the types of organisms present and their relative abundances (e.g. 50% of the individuals found in a community are species A, whereas only 2% are species F). In the heatmap, the more intense the colour the greater the percent representation of that taxon in the community. The colour pattern, and the dendrogram (branching diagram) at the top of the heatmap, show distinctly different communities associated with the high salinity periods compared with those from low salinities.
In general, microorganisms have very rapid reproductive cycles and thus can respond to changes in the environment very quickly. It may take much longer to see the response of macroorganisms.
From: Booth L. 2020. Temporal dynamics of microbial community composition in a brackish lake. UBC Okanagan Honours Thesis. 35pp.
