Question

Answer both required questions:

During this class, we discussed threats different marine mammal species face in the world today, as well as how their life histories may make it easier or harder for them to survive these threats. Rank the order in which each of the following four marine mammal species or populations is at risk of extinction (starting with 1 – highest risk and ending with 4 – lowest risk) and provide justification for what makes each group more or less vulnerable in relation to others on this list, focusing on possible threats and life history traits.

(A) Polar bear (Ursus maritimus) (B) North Atlantic right whale (Eubalaena glacialis) (C) Vaquita (Phocoena sinus) (D) Sea otter (Enhydra lutris)
(You will get 5 points for argument for each species and 5 points for overall order.)

In class, we discussed the “sequential megafaunal collapse” hypothesis. (A) In your own words, describe what Springer and colleagues meant by this idea and what evidence they had in support of it. (7 points)

(B) What were the main lines of evidence Wade and colleagues used in their paper published in 2008 in Marine Mammal Science to argue against the existence of sequential megafaunal collapse in the North Pacific? (5 points)

(C) Even after Springer and colleagues responded in 2008 in the same journal, the debate was not settled and is persists among the marine mammal community. Which side of the argument do you support? Provide a well-reasoned justification for your position. (13 points)

Answer 1

The list of marine animals under risk of extinction are as follows

1)Polar bears

2)Sea otter

3)Atlantic right whale

4)Vaquita

Polar bears- The Arctic climate is getting hotter resulting in melting of the sea ice which is the real source of their food.They have far higher metabolism than any other land predator which means they need to eat more food to maintain their energy demand.The hunting of marine animals like otter and seal mammals which comes under polar bears food list are very difficult due to melting down of land due to global warming

Sea otter-The oil tanker ships cause oil spills and water pollution in the ocean causing the life of otters under constant threat.The oil mat comes in contact with their fur and prevent them from insulating them self leading to hypothermia.Sometime organ failure like liver and kidney leads to loweing of their population around the world.

Atlantic right whale-The threat the come across are like ,hunting,colliding with the large ships,getting trapped in fishing net and their calving spot occupied by shipping.As there is not much population of them in the ocean from the beginning and now due to human needs their population are reduced much more.Global warning leading to warming of the water also cause extinction of the whale species.

Vanquita-Rapidly geting trapped in gill nets are one of the main reason of Vanquitas extinxtion.Illegal hunting for medicine and delicacies are another reason for reduction in their population.

Sequential megafaunal collapse-As per Springer and colleaques the mass extinction or collapse of the marine faunas of Northern Pacific Ocean is increasing.Threats like forced predation behavior on prey due to reduced number of usual small mammals,shipping,over fishing and hunting.The deterioration of a single species cause the predators to prey on higher species casing mass reduction of the ocean fauna.

B)Accoeding to Wade, et al,2008 ,The sequential nature of sea otter and pinnipeds like seals and porpise are core reason for SMCH. But the evidence was not accepted as it couldn't meet the required explanation.

C)Springer et al 2003 came with much evidence than Wade et al 2008 on SMCH.