Today some of the most trying questions involved in a family vacation is not the dreaded, “Are we there yet?” but rather, “Can Fido come too?” It is often a hassle and a bother to bring along the family pet, but it may help to keep the kids happy, so Muffles ends up tagging along. Years ago, during the age of exploration, when the European powers were darting across the world trying to prove their superiority, there were very few family vacations, and certainly not of the traveling distances that we can see today. But other people did travel and they did bring Fido and Muffles along, not because the kids wanted them to, but because the animals were of great value to any explorer. These animals, though helpful to the people who brought them, caused great damage to the ecosystems in which they were introduced.
The animals that were brought along were both useful on the ships which they came, and on land once they arrived at their destination. Dogs were used as hunters, trackers, as well as company. Birds could be used as scouts and as messengers. Other farm animals such as pigs, chickens and goats, could be used for milk, eggs and other purposes. And all of these animals could be eaten if times got tough and food was scarce. Fruits and vegetable where brought on board to prevent scurvy and provide some balance to a sailor’s diet. Seed were also supplied in the hopes that they could be planted for food if the party were to stop in one place for long enough.
While all of these animals helped the human partners they came with, they had hugely negative impacts on the ecosystems of the places that they were going. One or two members of a non-native species could wipe out entire populations of local plants and animals. This would then have a chain reaction as other plants and animals that were dependent on those would suffer and die or be forced to adapt. Today we understand this risk and countries restrict the transportation of foreign flora and fauna such as; fruits and vegetable, pets, and any other non-native species that may do harm to their own local, natural ecology.
One way in which the foreign species of plants and animals were destructive was actively kill their native counterparts. Dogs and other animals like them are natural predators. When they landed on a foreign shore their masters probably did their best to control them, but undoubtedly some escaped and started a new life in a new environment. Many of the indigenous animals that would be prey for these creatures did not know how to avoid being caught. They did not have the natural defenses that would protect them against these predators. It was only a matter of time before a large number of the local creatures were killed. Even if they were not driven to extinction, their dramatic decrease in numbers could have meant less food for their natural predators, an overgrowth of what those animals used to eat, or some other alteration of what their ecosystem was like.
Plants also did their part in changing the native environment of a place. While there are no plants that can be considered predators, there are plants that when put into competition with another plant for the same resources (eg. water, sun, nutrients) will prevail. Foreign vines may strangle the nutrients from another plant. A new type of plant may be able to survive form longer periods of time without water or sun and therefore gain an advantage in the forest. Non-native trees may be taller than native ones and therefore block the sunlight. Whatever the behavior explorers and settlers had no real way of knowing which plants would become dominant and eventually drive a native species out. However, they did inadvertently cause the downfall of many species of plants that were indigenous and had once thrived in their surrounding.
Insects were another problem for the environment that awaited the explorers. If there were no natural predators for the insects in the new habitat, then they could potentially destroy entire forests or species without any problems or setbacks.
Yet another way that foreign flora and fauna reacted havoc on their new environments was though disease. We have talked a lot about how disease was a powerful weapon in the hands of the Spanish invaders and other conquering armies, but what about in nature? Some of the most destructive pathogens that have been discussed have been cause by human-animal interaction. If animals can give these deadly diseases to humans, it follows that they could transmit them to other animals in a new and unprotected ecosystem. These diseases would be devastating to the species that they affect because there would be no antibodies or defenses against them.
One modern example of this is the transportation of ballast water by cruise ships. Cruise ships take in millions of gallons of ballast water, in order to stabilize the vessel for safe and efficient operation. During the process they take in thousands of species of marine organisms, including various types of larvae, fish eggs, and microorganisms. The water is often drawn in from coastal waters in one area, and discharged at another location. This allows for the unnatural migration of sea life that can have devastating effects on the coral, fish life, and other ecosystems of an area. One notorious example is the Chinese mitten crab, which was accidentally introduced into the San Francisco Bay area by cruise ships in the mid 1990s. In just a few years it became so abundant, due to a large supply of food and no natural predators in the region, that it was clogging water pumps in the Central Valley.
Although the transportation of plants and animals was extremely helpful to the explorers and settlers of many years ago, they have sometimes had devastating, and irreversible consequences on the new environments which they enter. By beating out native species for the resources needed to survive they drove out those species. By not having any predators in the area to keep them in check their numbers grew too large. And by introducing diseases that they had immunity to they were able to wipe out entire sections of an ecosystem. This was the environmental cost of human travel.
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