Humans have harvested the sea for tens of thousands of years, but only in the past few centuries have we begun to take a big toll on ecosystems. The two food webs below show predatory relationships among life-forms in the northern Adriatic Sea. Each web comprises humans, their prey and the prey of humans’ prey, distilled into groups of species.
The webs, produced by Jennifer A. Dunne of the Santa Fe Institute from evidence compiled by Heike K. Lotze and Marta Coll of Dalhousie University in Halifax, show that as recently as 1800 none of the Adriatic species groups had yet grown “rare,” or dropped below 10 percent of their former abundance. By the late 20th century, when the global economy had replaced local trade, 10 groups had gone extinct or rare, eliminating them from the webs.
Graphic by Jennifer A. Dunne. Interactive by Ryan Reid.
» Watch a video about food webs in this month's Graphic Science Web Exclusive "Food Webs Trace the Structure of an Ecosystem."
This article was published in print as "The Dwindling Web."
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3 Comments
Add CommentThat is one awesome jungle gym!
Reply | Report Abuse | Link to thisI see only the earlier web (1500-1800). Can't find the later web.
Reply | Report Abuse | Link to thisytrriem!
Reply | Report Abuse | Link to thisClick the "200 years later" tab.
The loss of taxa of a certain level disguises the far more serious loss that species provide to a thriving ecosystem. As some of you know, complex systems are more resilient>
You see in the first diagram some groups consuming more than one group of prey. These are called generalists, and when a niche opens, Darwin pointed out that species radiation will occur> That radiation results in speciation.
When rare or no predation from a species being extinguished, especially if that species has a slow repopulation rate, what is called release, or ecological relaease occurs.
The released species then tends to overbloom, sometimes toppling the balance of the web.
In the case of humans, we use our ability to accumulate information to avoid consequent re-predation upon ourselves as it were, and thus have exploded all over earth, ourselves replacing species more interactive.
Implicatino? We do not rebuild complex webs or systems. Instead we are generalizing our predation at all levels (processing many, many members of complex ecosystems into a far simpler web).
This poses some probabilities in the face of that well-understood resilience mentioned. We create a weak simple ecosystem, which I'd describe as vulnerable to new radiation. Medical science and related biology is well aware of outbreak of predation or parasitism upon our species, while largely ignoring the uncertainty or instability we have created.
Thus in our shortsightedness and solipsistic practices, we open the way for massive extinction in visible (and therefore to many or most, exploitable) organisms.
Yes this is an argument for the practicality of conservation, marine and terrestrial protected areas, protection of ALL species at risk from our own overradiation (in all its dimensions), determined contraception, and even evacuation of a considerable portion of remaining ecosystems - that is ceasing occupation and exploitation in significant portions of the earth.