Which animal species is the most negatively affected by indirect human activities?

Question

Realising the direct impact humans have on animal species is easy - it is obvious and intended. Changing one's actions so as to not impact these animals is therefore easy as well, one just stops doing this or that.

We do, however, affect animals in other, indirect ways as well, at times maybe even to a bigger extent than with the direct impact. I would therefore like to know which animal species is the most negatively affected by which indirect human activities. By indirect I mean anything where the harm or exploitation of animal is not the primary reason for an action, but merely a byproduct of it. Suggestion of alternatives is a welcomed addition to an answer.

EDIT: Seeing the answers this question inspired, I wanted to clarify what I would like to see in an answer so as it is not based on opinions but rather on data/reasearch.

• Answer is about an animal specie or genus, not some very broad taxonomical unit such as class.
• Answer provides some quantitative information about the impact, eg. number of animals killed/harmed/impacted or perhaps a % of population affected.
• Answer tries, where possible, to work with the indirect impact. While this can certainly be hard to do, I believe there is possibility of at least making an educated guess.

Answer 1

I think the most affected species are/were those that are either (completely) extinct or on. brink of extinction. A list of these species is found on this Wikipedia page (unfortunately the page is not homogeneously constructed as it mixes extinct species with almost extinct and other articles dealing with similar subjects).

I will try to also include information about how the extinction or near-extinction was/is produced due to human activity. Usually, there is more than onehuman activity that causes the extinction, such as climate change.

Some examples of extinct animals due to human activity:

• Dodo bird - assumed to be extinct in 1662. Cause: hunt by sailors and invasive species, while its habitat was being destroyed
• Eastern elk - declared extinct by the United States Fish and Wildlife Service in 1880. Cause: over-hunting and the loss of their dense woodland habitat.
• Laughing owl - largely or completely extinct by 1914. Cause: land use changes and the introduction of predators such as cats and stoats.
• California grizzly bear - assumed to be extinct in August 1922. Cause: over-hunting

Some examples on the brink of extinction are provided by this article (U.S. only). On the global level, this article tells us about really rare species (on the brink of extinction). Some highlights:

• Pika - less than 1000. Cause: grazing pressure from livestock and air pollution have likely contributed to their decline
• Giant Otter - less than 10000 in the wild. Cause: over-hunting, mercury poisoning
• Amur Leopard - about 60 in the wild. Cause: encroaching human populations and poaching
• Vaquita, world’s rarest marine mammal - about 60 in the wild. Cause: illegal fishing

It is hard to answer with a single species name since "most negatively affected" is not a clear definition, but I hope provided examples can fit quite well in this requirement.

To sum up the main causes (human related only, indirect): shrinking habitat (more land for human activity), pollution, changing the ecosystem by introducing of competing species.

Answer 2

The most affected species are fish and other sea creatures.

Because, per year, according to Wikipedia, 8.8 million metric tons of waste, including e-waste, are thrown into the sea. Radiation from the e-waste, chemical components and everything are making the life of ocean creatures difficult. They may either die, or get some disease and die slowly. This also causes problems to humans who eat the fish affected by chemicals or radiation.

More details on this issue can be found here.