In the 1960s Hess proposed that the crust separates along the rifts in the mid ocean ridges and that new seafloor forms by upwelling of hot new crust into these cracks. Magnetic anomaly patterns on the sea floor provide evidence. They are peculiar banded magnetic patterns found on the sea floor. By using the age of magnetic reversals they could calculate the rate of seafloor spreading using the equation speed=distance/time. Another line of evidence is the fact that rocks closest to the spreading ridge are younger and older rocks are further away. <span />
<span>The most closely related organism of genus species is Nerodia spedon and Nerodia fasciata, because they both water snake, from southern and northern part of america. And they came from large species, nonvenomous, native snakes, and aquatic type of snakes.</span>
Aerial stem structures that undergo modifications to perform these special functions include tendrils, thorns, hooks, phylloclade, tuberous stems and bulbils.
Aerial stem modifications are modifications to the aerial stems, vegetative buds and floral buds of plants growing in different conditions and which perform functions such as climbing, protection, synthesis of food, or vegetative propagation.
Answer:
Human impact on coral reefs is significant. ... Damaging activities include coral mining, pollution (organic and non-organic), overfishing, blast fishing, the digging of canals and access into islands and bays. Other dangers include disease, destructive fishing practices and warming oceans.Factors that affect coral reefs include the ocean's role as a carbon dioxide sink, atmospheric changes, ultraviolet light, ocean acidification, viruses, impacts of dust storms carrying agents to far-flung reefs, pollutants, algal blooms and others. Reefs are threatened well beyond coastal areas. Climate change, such as warming temperatures, causes coral bleaching, which if severe kills the coral.
In 2008, a worldwide study estimated that 19% of the existing area of coral reefs has already been lost, and that a further 17% is likely to be lost over the subsequent 10–20 years.[3] Only 46% of the world's reefs could be currently regarded as in good health [3] and about 60% of the world's reefs may be at risk due to destructive, human-related activities. The threat to the health of reefs is particularly strong in Southeast Asia, where 80% of reefs are endangered. By the 2030s, 90% of reefs are expected to be at risk from both human activities and climate change; by 2050, it is predicted that all coral reefs will be in danger.
