Are we reaching a biodiversity tipping point?


On Wednesday, September 22, I attended a seminar at the Virginia Institute of Marine Science (VIMS) in Gloucester Point, Virginia, entitled “What’s Happening to Our Native Plants and Animals?” The series of talks began with a presentation by Dr. Roger Mann about invasive species in the Chesapeake Bay.

The Chesapeake is one of the world’s largest estuaries with its mouth opening to the Atlantic Ocean in southern Virginia and its headwaters in New York State. This bay, in my back yard, was probably invaded by 16th century explorers, but it was certainly invaded in 1607, when the English came to the North American continent that they named Virginia, for the virgin Queen Elizabeth, and established their first permanent settlement at Jamestown (just 3 miles from my home).

By the end of the first hour of the seminar, listeners were generally shocked and depressed. Of course, as environmentalist we already knew about the decline of our keystone species, oysters, and the despoiling of our tidal wetlands by Phragmites australus. But for most of us, these new studies on the impact of non-native species were not well known.

After lectures on honey bees, bats, emerald ash borers and more, the picture of thousands of species once relatively contained and now moving about around the globe came into focus. I realized that the world is a vast reservoir of species that have evolved over tens of thousands of years to support a web of life in their local sphere of influence. After humans discovered that the world is round and began to actively explore it, just a few hundred years ago, we quickly moved species to new places where they were not part of the elaborately evolved system of life.

Microorganisms clinging to the ballast in European ships were spilled into ports on the other side of the world where ships were loaded and new organisms were hiding in the packing material that swaddled Chinese export porcelain. We have been moving tiny life forms as well as all sort of flora and fauna from place to place for hundreds of years. Flower bulbs, trees, slaves, pigs, as well as their crates, food, clothing, all contained a diverse array of additional organisms.

In the end, what all of the presenters at the VIMS seminar told us is that the introduction of new species causes problems, large and small. Non-natives that thrive can out-compete natives in new lands where they have no predators. In the U.S. Phragmites has overwhelmed plants that tidal wetlands creatures used to eat and kudzu (plants in the genus Pueraria) trollops over the landscape using up all the energy and strangle the life out of native trees. While all non-natives aren’t invasive, like Phragmites and kudzu, all chip away at the healthy biodiversity of an ecosystem.

The problem has grown as we have traveled more and longer distances on ships, trains, and airplanes. Our imports and exports unleash new invaders on unsuspecting natives daily. One presenter showed us movies from the 1950s of space aliens and monsters terrorizing New York City to bring some laughter into the room. Another told us that when the new and wider Panama Canal opened to allow through new supercargo container ships filled with goods from Asia on their way to United States east coast ports, the work of scientists, inspectors and regulators would greatly increase.

So the phrase I want to introduce to you today is “sustainable biodiversity.” Our biodiversity is threatened; our Chesapeake Bay oysters are no longer commercially viable in part due to invasive parasites. But can we bring them and other stressed native species back? Can we contain the loss of biodiversity? What is a sustainable level of biodiversity loss and how shall we limit the impact of invaders?

There are many ways, but there isn\’t enough effort being spent to eradicate invasives and maintain the a healthy level of biodiversity. This is a big problem that is increasing as the world warms. Non-natives that thrive in a new ecosystem quickly out-compete weakened natives. The web of life unravels very quickly indeed.

Follow my blog posts as I work to sustain biodiversity by giving a few stressed species a hand.