Environmental Concerns: Habitat Fragmentation

What is it?

Discontinuities in an organism's preferred environment causing population fragmentation (a form of population segregation). Habitat fragmentation includes 5 discrete phenomena:

• Reduction in the total are of the habitat
• Increase in the interior-edge ratio
• Isolation of one habitat fragment from other areas of habitat
• Breaking up of one patch of habitat into smaller patches
• Decrease in the average size of each patch of habitat

What causes it?

Natural causes

• Volcanism
• Fire
• Climate Change

Human Causes

Habitat fragmentation is frequently caused by humans when native vegetation is cleared for human activities such as agriculture, rural development, urbanization, and the creation of hydroelectric reservoirs. As a result of these activities, habitats that were once continuous become divided into separate fragments. These separate fragments tend to be isolated from each other separated by cropland, pasture, pavement or barren land. 

Implications

Habitat fragmentation reduces the amount of available habitat (such as rain forest, oceans, marshlands, etc.) for all organisms in an ecological niche. It also involves some degree of habitat destruction. Plants in these areas are usually directly destroyed while mobile animals like birds and mammals retreat into patches of habitat. This often results in crowding and increased competition which may be due in part to the fact that the remaining habitat fragments are smaller than the original habitat. Another issue with fragmentation is that species that cannot move between fragments must make due with what is available in the smaller, isolated patch of habitat; unfortunately, habitat fragments are rarely representative samples of the initial landscape making it difficult for less mobile species to survive. Thus, of significant importance is the area of the fragment.  The size of the new habitat influences the number of species which are present when the fragment was initially created and also influences the ability of these species to survive in the fragment. Small fragments can only support small populations of plants and animals; small populations, however, are more vulnerable to extinction. Therefore, habitat fragmentation is an important cause of species extinction.

Source:
http://www.eoearth.org/article/Habitat_fragmentation?topic=58074

CCD and What it Means for the Honey Bee

What is Colony Collapse Disorder (CCD)?

Colony collapse disorder: (n.) a phenomenon in which worker bees from a beehive or European honey bee colony disappear. 

• Term was applied in 2006 to the drastic decrease in honey bee colonies in North America
• Similar phenomenon observed in Belgium, France, Netherlands, Greece, Italy, Portugal and Spain 
• Significant because many agricultural crops worldwide are pollinated by bees

Signs

• Presence of capped brood (unhatched bees) in abandoned colonies. Bees will normally not abandon a colony until the capped brood have all hatched
• Presence of food store, both honey and bee pollen not immediately robbed by other bees and when attacked by hive pests, the attack is noticeably delayed
• Presence of the queen. If the queen bee is not present, the hive died because it was queenless which is inconsistent with CCD

Symptoms

• Insufficient workforce to maintain the brood that is present
• Workforce made up of young adult bees
• The colony members are reluctant to consume provided feed such as sugar syrup

Background:

Between 1972 and 2006, there was a dramatic decrease in the number of feral or wild bees as well as a steady decline in the number of colonies maintained by beekeepers. Factors contributing to this decline include urbanization, pesticide use, tracheal and Varroa mites and the retirement or going out of business of many commercial bee keepers. Many researchers and bee keepers specifically believe that the introduction of systemic neonicotinoid pesticides in 1994 are the catalyst for the decline in honey bees. Neonicotinoid pesticides are absorbed into every part of the plant, including the root, stems, leaves and pollen. When bees pollinate, they unfortunately carry these harmful pesticides back to their hive which then decimates the colony.

While bee losses remained stable throughout 1990s averaging about 17-20% per year, bee keepers were reporting losses of about 30-90% of their colonies by 2007. In some instances, losses were so severe that the weakened surviving colonies were no longer able to pollinate or produce honey. In 2010, the USDA reported overall honey bee losses were an estimated 34% which was similar to losses in 2007, 2008 and 2009. The United States alone has seen its honey bee population decrease to 2.44 million down from 4.5 million in 1980 and 5.9 million in 1947.

Why Should We Should Care?

Honey bees are essential to the pollination of a number of important crops. For example, in 2000, the total U.S. crop value that was completely dependent on honey bee pollination exceeded $15 billion. Honey bees are primarily responsible for the pollination of one third of the United States' crop species including:

• Almonds
• Peaches
• Soybeans
• Apples
• Pears
• Cherries
• Raspberries
• Cranberries
• Blackberries
• Watermelons
• Cantaloupes
• Cucumbers
• Strawberries

Many of these crops can be pollinated by other insects in small holdings in the United States, but usually not on the commercial scale. Beehives can be moved from crop to crop as needed compensating via saturation pollination for what they lack in efficiency. Therefore, the commercial viability of these crops is strongly tied to the bee keeping industry. So why should we care? Without a thriving bee population, produce prices could increase substantially and the food industry could lose billions of dollars. Therefore, we should care because a declining honey bee population, could spell disaster for the sustainability of many U.S. crops and could have a deleterious effect on the ecosystem.