Hey Ma, Pass the Jellyfish

The following was published in the Cranbrook Daily Townsman in the fall of 2009.

“I wish I was a jellyfish, floating on the sea
Riding on the currents sailing along so peacefully.” 
~ Bobs & Lolo

One of the most stunning natural history exhibitions I have ever seen was at the Monterey Bay Aquarium. Their jellyfish display featured a dark room with various sized aquaria back-lit such that their inhabitants glowed. Floating effortlessly, I could have sat entranced for hours watching, just going with the flow.

 According to recent work by marine biologists, we may have a lot more opportunity to ponder jellyfish. A review by four scientists published the June, 2009, issue of the scientific journal Trends in Ecology and Evolution cautions that “a more gelatinous future” is clearly in the offing unless we take steps now to change the way we treat and manage the oceans. Jellyfish outbreaks are being reported worldwide, often with disastrous effects.

Of course jellyfish are a natural part of ocean ecosystems. Fossil evidence suggests they were they dominated the Cambrian seas some 500 million years ago, long before other vertebrate and invertebrate life forms we know today had evolved. They remain important as food for not just other sea creatures, but humans as well. Many Asian cultures eat jellyfish – some 425,000 tonnes each year by some estimates.

More often, they are viewed as a nuisance at best and hazardous risk to human life at worst. The list of deleterious consequences is long: closed beaches, blockage of cooling intake pipes for coastal power generators, fouling fishing nets, killing farmed fish, reducing commercial fisheries. Most often, human interference with marine systems has led to great increases in jellyfish numbers around the world, and the potential consequences are not pleasant.

The causes of jellyfish increases are not surprising: overfishing, eutrophication, climate change and accidental introductions from ship ballasts. The largest problem seems to come from a reduction in small filter feeding fish populations. Two examples cited are the sardine fishery off the coast of Namibia and anchovies in the Black Sea. Both of these fish play key roles in suppressing local jellyfish numbers, largely by eating their larval stages. With the fish gone, the jellies quickly multiply and the adults assume the plankton-eating niche that the sardines and anchovies occupied. Jellyfish biology is such that a self-enhancing feedback system sets up leading to rapid increase in jellyfish numbers.

Increased runoff of fertilizers and sewage has also benefited jellies. Increased nitrogen and phosphorus is advantageous to phytoplankton (including red-tides). This comes at the cost of more silicon-based diatoms. Jellies prefer phytoplankton, while most fish, marine mammals, turtles and other species prefer diatoms. Jellyfish win again. Phytoplankton blooms can lead to low oxygen levels, something jellyfish deal quite well with, while other animal species cannot tolerate.

Climate change has similarly favoured jellyfish. Warmer waters have allowed potentially fatal species of jellyfish, such as the box jellyfish of northern Australia to expand southward toward more populated swimming beaches. Warmer temperatures lead to nutrient-poor surface waters, a condition, like eutrophication example above, that favours jellyfish.

Finally, the commercial shipping industry has played a role in inadvertently introducing jellyfish to new areas. Like many other species, they can become invasive and without natural predators or other forms of regulation they rapidly increase in numbers to the point of greatly altering native ecosystems. The Black Sea, Caspian Sea and Gulf of Mexico have all witnessed introduced jellyfish problems in recent years.

The concerns are significant. Our current actions are potentially driving the seas away from those dominated by diatoms and fish to one of phytoplankton and jellies. Some scientists have suggested that if current trends continue, our oceans could soon more resemble the warmer, more eutrophied Cambrian seas of 500 million years ago.

No one is suggesting that jellyfish are driving fish and whales to extinction. It’s just that jellies and their ancient, time-tested adaptations are able to quickly take advantage of the opportunities that have been provided to them.

Thankfully, there are several options available to us. Mostly, these involve reversing the actions that have allowed for the recent proliferation of jellyfish: over-fishing, eutrophication and climate change. If we don’t, the seas may well be a vastly different place than what we are familiar with today. And instead of singing the children’s song quoted at the top, we’ll be following the advice of fisheries scientist Daniel Pauly, “My kids will tell their children: eat your jellyfish!”

Springtime out of tune

This column was published in the Cranbrook Daily Townsman Friday May 14, 2010.

Yellow bird, yellow moon
You've arrived while the spring is out of tune
- Justin Rutledge, from "Jack of Diamonds"
 

The un-spring like view of our driveway

I confess I've never heard Justin Rutledge's music, but a review of one of his concerts included this lyric. Though out of context for a late-season snowfall, it seemed fitting for recent East Kootenay weather. A week ago our spring was badly out of tune.

Quite a difference a week can make. Last Friday we awoke to a winter wonderland with Christmas carols the most appropriate lyrics. Pretty enough, I suppose, but winter weather occurring during winter (where was this snow in February?) seems a better idea.

So what happens to the yellow birds and when they arrive from their tropical winter paradise only to find that spring is "out of tune"? We don't find piles of dead birds under trees, so how are they able to cope with such weather anomalies?

The unfortunate answer is that some don't. Late cold snaps (or early autumn ones like last year's Thanksgiving weekend's -15°C) take their toll on wildlife, particularly pint-sized songbirds. However, most adults are able to withstand brief periods of unseasonable cold.

That the cold and snow occurred before most species had young in their nests is very helpful in avoiding widespread mortality. There may have been some egg failure among early nesting species such as robins, but snow at the end of May it is far more damaging.
 

Most songbird nests are highly exposed to the elements and baby birds, often still featherless, are very susceptible to cold, snow and heavy rain. Cool springs or one freak storm can wipe out a large percentage of a year's songbird production across many species. Some may lay a second clutch of eggs, but many pack it in and wait for another year.
 

Hummingbirds, having returned for the summer nesting season, instead met with a big white surprise. But the physiological adaptations of these tiny marvels are astounding. Their small body size and highly active lifestyle means they have incredible energy demands which would otherwise leave them vulnerable to cold temperatures. However, the advantage of small body size is that warming up and cooling down are easy and efficient. Even most nights in summer, they slip into a torpor of slowed metabolism and lowered body temperature. Normal temperature for most birds, including hummingbirds, is in the 40ºC range. But in torpor, that can drop close to below 15ºC. The advantage is that their metabolic energy demands drop by 50%.

In fact, the greatest danger to endotherms (animals which can regulate their internal temperature - birds and mammals) is overheating. Normal body temperature is very close to the point of irreversible cellular damage. Living on the edge like this may seem dangerous, but speeds metabolism and movement of nutrients across membranes as well as optimizing nerve transmissions. Maintaining a high brain temperature may also assist in learning and memory.
 

Many so-called cold-blooded animals (more properly termed ectotherms) rely on behavioural adaptations to survive the cold and snow. Snakes just emerging from their underground winter hibernation sites will quickly retreat to their subterranean warmth. Frogs either stay submerged in water or seek refuge under forest floor leaf litter and rely on their ability to withstand some freezing.
 

So while spring may occasionally be "out of tune", it's certainly not entirely out of character. And as for the older song that waxes poetic about "Springtime in the Rockies", I doubt the author ever spent many springs in the mountains. It can be the cruelest of seasons.

The Sound of Spring

The following was published in the Cranbrook Daily Townsman, Tuesday, May 4, 2010.

For most, the sound of spring is the clamour of bird song. After the long silence of winter, hushed by layers of snow (or maybe not, this year!), the return of songbirds from their lush tropical dreamland brings a welcome music to the early morning sunlight. The gathering chorus, added to daily by new arrivals, grows earlier as dawn heads steadily north. In the evening, the robin, soon joined by other thrush cousins, sings a vespers to the enclosing darkness.

But if you are lucky enough to live close to a pond or wetland, that evening song is soon joined by another voice. This one more rhythmic than melodic. Steady. Emphatic and determined. The steady krek-ek… krek-ek… of the Pacific tree frog is as much a sign of spring in the East Kootenay as any crocus or bluebird.

Pacific tree frogs are one of the more common amphibians in southern British Columbia, occurring from the coast east to the Rocky Mountain Trench. Highly variable in colour as a species, we here in the East Kootenay get the drab olive variety, with a black triangular mask behind their eyes. They’re small in size – rarely more than 5 cm long. Their range ends as the Lizard and Galton ranges climb from the valley into west slope of the Rockies. But many small ponds, sloughs and wetlands throughout the Trench are the site each spring of a ritual pilgrimage for the tiny amphibians.

For an animal that is reliant on the whims of fickle spring weather, frogs are remarkably adapted to cold. Some nights when the temperature battles hard to remain above freezing, we can still hear the frogs croaking away in late April.

As the snow melts and frost eases from the ground, tree frogs emerge from their hibernation – a winter spent under the chilly blanket of dead leaves and other forest floor cover. Many frogs have an physiology adapted to super-cooling that allows them to virtually freeze during the winter. Provided they are not disturbed, they literally thaw out the next spring and start their year anew.

They return to ponds each spring only to breed and lay eggs. As all amphibians, their larval stages are fully aquatic. Tree frog tadpoles or pollywogs develop rapidly, metamorphosing into terrestrial adults within two months. They have to grow quickly, for their pond is often ephemeral and dries out under the summer sun.

Like most tree frogs, their toes have suction cups on the end to facilitate climbing into their eponymous lair of small trees and shrubs where they spend most of the season, often quite distant from water. Here they feast on a typically froggy diet of insects, spiders and other bugs caught from their not-so-lofty perches. Unlike most frogs, which only call during the spring breeding season, Pacific tree frogs often just can’t hold back. Any particularly glorious night of rain and damp misery may elicit a song of apparent joy from a tree frog’s throat.

However, ours is not a particularly joyful time for amphibians. Species the world over are in decline, and BC is by no means sheltered. Chytrid fungus, originally from Africa, has been unwittingly spread worldwide with devastating effects on our frog populations. Reducing transmission by not handling frogs and not visiting different ponds is the best way to restrict the disease. Any mass die-offs of frogs should be reported to the British Columbia Ministry of Environment.

This year, the pond in our neighbourhood is dry. The water table lowered from lack of snow and too long without rain. We have not yet heard the frogs, though I know they are singing elsewhere. I miss the call, lying in bed with the window open at night listening for their spring ritual. Species fated to the whims of climate are well adapted to adjust to a occasional dry years. We just hope this is an anomaly and not a portend of conditions to come. A spring without tree frogs is far too silent.