`Red alert' issued for Stanley Park aquatic life
Tree cover growing, but 46 native species now at risk, ecological watchdogs report
Stanley Park's tree cover is growing, but aquatic life in Beaver Lake isn't doing very well at all, according to a new report on the park's ecological health.
The report by the Stanley Park Ecological Society found that the park is home to 1,031 native species that include 239 birds, 27 mammals and two reptiles. The biggest group are invertebrates and zooplankton at 325. The 46 native species at risk include western grebe, double crested cormorant and little brown mouse-eared bats.
Ariane Comeau, conservation projects manager, said that from 2013-15 the park's tree cover increased by eight per cent because 15,000 trees and shrubs were replanted to replace more than 10,000 trees lost during the windstorm of 2006.
“It's really great to see,” Comeau said. “The tree cover has significantly increased in the blowdown areas.”
The report, however, issued a “red alert” for fresh water ecosystems such as Beaver Lake and Lost Lagoon.
“Water temperatures are high in Beaver Lake and Lost Lagoon and oxygen levels are exceptionally low in Beaver Lake, to the point where they're reaching lethal levels for salmonids and amphibians,” the report summary says. “Without proper intervention, the situation is expected to worsen.”
Comeau said the SPES is seeing more hardy species such as the three-spined stickleback and invasive species such as carp.
“Both are known for being able to survive in harsh conditions,” she said. “The fact that these are the only ones we're seeing recently is quite alarming.”
One of the native species that hasn't been seen in freshwater areas for decades is the northern red-legged frog.
Conditions are changing rapidly at Beaver Lake because of pink and white water lilies that were introduced in 1938 to celebrate the 40th anniversary jubilee of Dutch Queen Wilhelmina.
By summer, water lilies cover almost all of the water's surface. Whey they die, they produce so much biomass they're filling up the lake and making the water shallower.
When that happens, the water can warm dramatically, especially during summer months.
In 1938, Beaver Lake was 6.7 hectares in size; today, it's less than 3.9 hectares.
Each spring, classes of students release salmonids into Beaver Lake as part of a Department of Fisheries and Oceans initiative. But warming conditions mean it's not safe for the fish.
After the last report on the ecological health of the park in 2010, the park board developed an ecological plan for Stanley Park that included dredging parts of Beaver Lake to create deeper, cooler areas. But as yet no dredging has taken place.
Comeau is releasing the full State of the Park Report for the Ecological Integrity of Stanley Park 2020 today, before the ecological society's virtual annual general meeting at 8 p.m.
While the park's seawall is a major tourist attraction, it also affects the park's ecosystem by limiting nutrient exchange between the intertidal areas and the land.
The report says that, in future, the seawall will amplify negative affects of climate change by contributing to coastal squeeze: as ocean levels rise, the size of the intertidal area will be reduced, which will in turn lead to a reduction in food sources for mammals and birds.
Some of the park's ecological restoration and habitat enhancement initiatives since 2010 have included building a boardwalk in Cathedral Trail, installing 23 nest boxes for swallows and wood ducks in Lost Lagoon and Beaver Lake, and removing more than 800 cubic metres of invasive plants.
“The main goal is really to have a better idea of what exists, how things are doing, how things are changing ecologically,” Comeau said of the report.
“Having this information helps stewardship or management plans to better protect ecosystems and species in the park.”
When the next report is released in 2030, the ecological society hopes to incorporate traditional ecological knowledge of the Musqueam, Squamish and Tsleil-Waututh nations.
The new report says that “knowledge” would encompass “a more holistic picture of the park's ecological integrity,” which would take into account the use of the land in pre-park times.