Milestone Looms for Farm-Raised Fish ∞

Craig Leisher, reporting for the New York Times:

In the last 20 years, the production of fish through aquaculture has grown exponentially, while marine fish catches have leveled off. Unless it’s an extraordinary year for marine fishing, in 2013 the lines will cross, and the majority of the fish we eat will come from aquaculture rather than oceans.

That’s good and bad. Fish are efficient sources of protein—for every pound of feed, they put on a pound of flesh. But fish farms can be tremendous polluters, and other aquaculture ventures like shrimp farms have devastated mangroves in Southeast Asia. 

How urban design affects our health ∞

Behavioral psychologist James Sallis, being interviewed by Ivan Semeniuk for the Globe and Mail:

Throughout our whole history, people have walked for transportation. We’ve deleted that. We’ve designed that feature out of the world for many, many people and we now have the evidence that our planning and community design decisions and our transportation decisions are reducing activity and contributing to chronic diseases.

Anthropocene good for arachnids ∞

Bridie Smith, reporting for The Age:

After comparing 222 spiders – including measuring size, weight and body fat – Miss Lowe found city spiders were bigger than those from the bush. She also established that within urban environments, spiders were bigger when they were found closer to man-made objects.

Why Talking Cars Will Be Good for Buses ∞

Emily Badger, reporting for the Atlantic Cities:

Cities around the world are increasingly turning to the relatively affordable transit solution to move more passengers on dedicated bus lanes without the unpredictability of traffic congestion or the cost of constructing railways.

One problem with BRT, though, is that plenty of drivers aren’t eager to see whole lanes of busy roadway blocked off exclusively for bus use. So this is where connected vehicle technology could come in. If buses and cars could communicate with each other, drivers could use BRT lanes when buses aren’t around.

I’m guessing that the line between public and private transit will be increasingly blurred as autonomous vehicles become widespread. If you can request a vehicle on demand, what’s the purpose in owning your own car? 

"Friendly neighborhood serial killers" ∞

Gerry Mullany, reporting for the International Herald Tribune:

Gareth Morgan, an economist and environmentalist, says that the cat is actually a “friendly neighborhood serial killer” when it comes to birds, and his Web site suggests that New Zealanders should gradually reduce the local feline population by having all cats neutered, and that when cats die, their owners should not replace them.

I’m guessing Morgan will be receiving a lot of unfriendly mail, and not because he’s misstating any facts.

The Five Types of Territorial Morphology ∞

Frank Jacobs:

Do Norwegians feel curiously at home in Chile, and vice versa? Do South Africans have a strange affinity with Italians? And Filipinos with Maldivians? They should, at least if they’re map nerds: each lives in a country with a territorial morphology that closely resembles the other’s. 

DNA, the computer storage of the future ∞

John Timmer, writing for Ars Technica:

In general, though, the DNA was very robust. The authors simply dried it out before shipping it to a lab in Germany (with a layover in the UK), where it was decoded. Careful storage in a cold, dry location could keep it viable for much, much longer. The authors estimate their storage density was about 2.2 Petabytes per gram, and that it included enough DNA to recover the data about ten additional times.

That’s incredibly dense. No wonder living things use DNA as their blueprints and operating manuals—you can squeeze a lot of instructions into a lightweight, efficient package. 

Fracking, as seen from space ∞

Robert Krulwich:

It’s a little to the left, high up near the Canadian border. Just run your eye up that line of lights at the center of the country, look over to the upper left: There’s a patch that looks like a big city — but there is no big city in that part of North Dakota. There’s mostly grass. So what are those lights doing there? What is that?

Time to Embrace Exotic Species? (Or at Least Some of Them) ∞

Matt Palmer, writing for The Nature of Cities:

Family narratives and history books are full of stories about about the hard times that waves of human immigrants found in their new homes.  Non-human immigrants – often referred to as exotic, introduced, or non-native species – have received a similarly cold welcome in most places.  But the movement of plants and animals across the planet is both ancient and inevitable.  It is also increasingly difficult to control.  We face choices about which movements to resist and which to allow or perhaps even encourage.  We also have the opportunity to plan as well as we can to get the most from our changing ecosystems.

Eric Fischer's personal geography of 2012 ∞

Eric Fischer mapped his movements in and around his hometown over the past year:

In general, black is walking, red is bicycling, blue is cars or buses, and green is above-ground rapid transit or freeways. (Color is from speed, not from an actual record of transportation mode.) Not shown: tunnels and subways.

How big is your world?

I like the idea of color denoting speed, not mode—isn’t that what really matters for transportation?

Against invasive plants, underdog natives hang on

Dianella ensifolia

One of the scourges of our globalized economy is invasive species. In California, annual Mediterranean interlopers have upended the state’s once perennial grasslands. The Australian outback has been blanketed with prickly pear cacti from the American Southwest. And wattles from Down Under are a scourge in South Africa. But as widespread as invaders are, we’re only just beginning to understand how they move around the globe, establish themselves, and reshape the ecosystems they disturb.

A key unsettled debate is whether or not invasive plants change patterns of biodiversity. Some studies have found that biodiversity suffers when nonnative plants arrive and take over. Others have found the opposite, that new species add to the mix rather than deplete or homogenize it. Well, the authors of a new paper published today in Science say both answers are right. According to them, it’s all a matter of scale.

Studies on invasive plants and biodiversity can generally be classified according to scale, small and large. Small scale studies pore over tiny patches of land, generally less than 25 square meters. In those cases, researchers have generally found that plant biodiversity suffers when invasives are present. Other scientists say that, on the large end of the scale, they see no difference.

In an attempt to reconcile these consistently disparate findings, Kristin Powell of Washington University in St. Louis and her colleagues sought to bridge both scales. They set up both large (500 m2) and small (1 m2) plots in Hawaii, Florida, and Missouri, each of which has its own problematic nonnative. In Hawaii, it’s the fire tree, Morella faya; in Florida the cerulean flax lily, Dianella ensifolia; and Missouri the Amur honeysuckle, Lonicera maackii. The study subjects run the gamut from overstory tree (fire tree) to mid-story shrub (honeysuckle) to understory herb (flax lily). Each state in the study has parts that are invaded and parts that are not, a fact which Powell and her colleagues used to their advantage by surveying plots on either side.

What they found is as nuanced as you might expect from a confused and messy situation involving the natural world. On small scales, the 1 m2 plots, they found that biodiversity was, in fact, lower. In the large plots, species richness was a slight bit lower, but it was close enough to be a wash. These results essentially jibed with those found by other scientists.

If you dig a little deeper, things get more interesting. They also found that ecosystems hosting invasive plants are generally more homogenous—the patchy pastiche you would normally expect just wasn’t there. But they’re not ecological clean rooms, either. Though diversity was down, there didn’t seem to be evidence of extinctions. Native plants may have disappeared from a large number of the smaller quadrats, but they typically weren’t absent from the larger plot. The diversity was there, it was just hiding among the invaders.

That’s good news, in a way. We probably won’t lose interesting and potentially important plant species because of competition from invasive plant species. But that’s not to say the natives are free and clear, though. If their populations are suppressed too much, they could be sitting ducks for another disaster, such as a catastrophic fire or human development. They’d be one step away from being wiped off the map.

This study’s results suggest that we should reevaluate how protections like the Endangered Species Act can—or can’t—help in the case of invasives. If, as this study says, invasions seldom lead to extinctions, then protections like the ESA won’t help much against invasive species. But if invasives depress population numbers enough, native species would be vulnerable, meaning the ESA would be more relevant than ever. In those cases, we should be even more vigilant in areas overrun with invasives. On the surface, they may not look like healthy ecosystems. But lurking within are the native remnants of one. If we buy those systems enough time, they may sort themselves out.

Source:

Powell, Kristin I., Jonathan M. Chase, and Tiffany M. Knight. 2013. “Invasive Plants Have Scale-Dependent Effects on Diversity by Altering Species-Area Relationships.” Science 339: 316-318. DOI: 10.1126/science.1226817

Photo by SSKao.

Related posts:

An ecology of gardens and yards

Thinking about how we think about landscapes

Wilderness housing boom challenges conservation

When Pittsburgh was like Beijing ∞

Alexis Madrigal

As America became an industrial power during the 19th century, Pittsburgh emerged as the seat of metalworking, iron and then steel. This was a city powered by coal. Soot and smoke covered the city. There was no blue sky. Travelers from around the world visited Pittsburgh to see the wonder of American capitalism. The stories they tell are like — exactly, like — the ones you hear today about China. 

Mapping climate change ∞

Your warming world

Peter Aldhous of New Scientist and developer/journalist Chris Amico have developed a fantastic web app that lets you see how climate change has affected your locality. Click on the map or enter a city and you’ll see temperature trends for the last 130-plus years for that exact location. Sobering.

Beijing's Air Quality Catastrophe ∞

If you haven’t been following the horrendous air quality Beijing that’s blanketed Beijing, take a look at this post by James Fallows at The Atlantic. Visibility is almost nil, readings are literally off the charts, and I’m certain it’s acutely hazardous to people’s health if they step outside.

As Fallows notes, such environmental disasters could lead to the undoing of China’s recent economic successes:

This is yet another reminder of a fact impossible to forget when you’re inside China but that often gets glossed over in credulous accounts of the New Chinese Century. Namely, that economic growth has come at the cost of environmental disaster, which is in turn (according to me) the most urgent and important of several limits and dangers the Chinese system faces. Every country as it develops has gone through its hellish-despoliation era, and of course the world as a whole is still at this stage. But the scale and speed of China’s transformation make its case unique.

Beijing air pollution, as seen from space ∞

Beijing air quality from space

MODIS captured this image of Beijing’s terrible air quality on January 14. Yellowish clouds are those laced with air pollution, which if you look closely are fairly extensive.

Reviving Europe’s Biodiversity By Importing Exotic Animals ∞

Christian Schwägerl, reporting for Yale e360:

The Töpchin project is an example of a growing conservation trend in Europe — using large, exotic herbivores to enhance the diversity of native flora and fauna. Many people still believe that nature conservation is all about leaving native plants and animals alone, or restoring their habitats to a wild state. But in a world dominated by humans and rapid environmental change, things have become more complicated. The answer isn’t always to strive for a regionally “pure” mix of native species. A growing number of conservationists now seek to employ exotic species for managing native biodiversity.

The drivers who make Bay Area traffic unbearable ∞

Mike Rosenberg, reporting for the San Jose Mercury News:

A groundbreaking study by UC Berkeley and MIT researchers has pinpointed a small group of drivers making Bay Area freeways miserable for the rest of us, though the reason may surprise you. These commuters aren’t necessarily slow or bad drivers. Instead, they come from a few outlying neighborhoods and travel long distances together in the same direction like schools of fish—clogging up not only the roads they drive on, but also everyone else’s.

(Via Emily Badger.)