Geography Reference
In-Depth Information
Birds, mammals, and herps have charisma. They dazzle us with beauty, song,
and mystique. Most get our attention, and some scare us. Relatively speak-
ing, biologists know these animals well, especially those that live among our
homes and businesses. The insects, marine creatures, and even many fresh-
water i sh and invertebrates, by contrast, are less well studied and often poorly
understood. Humans are landlubbers, so this bias toward knowing those
whose lives are most similar to our own is understandable. But Earth is only
one-quarter land, and by far and away the majority of life forms are tiny, lack
a backbone, and inhabit the aquatic world we i nd so foreign. Urban ecolo-
gists are just beginning to understand how such animals take to the city, but
many of their discoveries echo themes we've explored from our vertebrate
perspective.
The importance to amphibians of connecting terrestrial and aquatic envi-
ronments is easy to see, as they literally live in both worlds. Marine and fresh-
water creatures are, in contrast, wholly aquatic, yet their existence is also
closely tied to our actions on land. Major cities of the world are sited on coasts
and profoundly inl uence the seas upon which they rely. Piers, bridges, sea-
walls, busy ports, and el uents af ect the physical structure of the shore, the
hydraulics of currents, and the chemistry of water. Globalization of com-
merce, and the human activities that support it, is responsible for many intro-
d u c t i o n s o f n o n n a t i v e s p e c i e s — f r o m f a vo r i t e t r o p i c a l i s h t o z e b r a m u s s e l s — i n t o
ports, harbors, canals, and lakes. The ecological and economic costs of such
invasions are devastating. In addition to changing the physical and biologi-
cal aspects of habitat—sands, reefs, and fringing plants where marine life
thrives—many marine species are directly exploited for food and bait. Yet de-
spite these inl uences, marine systems appear more resilient to urbanization
than their terrestrial counterparts, where loss and degradation of living space
are more severe. Our freshwater systems may be especially sensitive. Rivers
are frequently overworked to transport goods, water crops, provide power,
 
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