Using Blogs for Academic Research - Is this Ethical?

It is estimated there are tens of millions of blogs currently used on the internet, the most public environment. Due to the internet being such a large public space, some researchers suggest that there need not be any code of ethics, as these bloggers must be aware that people may use their blogs as sources of information, such as research or journalism (Eastham, 2011). However we all know that with any sort of research, ethics should be considered, therefore in terms of privacy and consent should there be a code of ethics for blogs too?
If something is posted into a public space, and there is no log in needed to view it, then technically you would consider it public property. Wilkinson & Thelwall (2010) say that there shouldn't be restrictions placed on data on the internet, and that if it has been posted to a public domain then it should be publicly obtainable. They also argue that those who post online can't complain about a breach of privacy as the fact that the information they have posted has been in a public space makes the information public. 
'Privacy' is a word which meaning changes through time, and also depending on the context. Unless there is a log in method placed on a blog then there is no way to limit who the audience is. Therefore many go for the use of a pseudonym, which can hide their identity in a particular public space. Bruckman (2002) found that some use pseudonyms for use just of their blogs, and others use them for all social activity on the web. Some also use avatars for their online picture, which may be a graphic representation, or a picture of their choice. This furthers the mystery of who the author is, making a more private setting in a very public space. Bloggers make conscious privacy choices that researchers then must discern and respect. The blog that is identified via a search engine and that is open to responses from others is clearly a public blog.
It would be almost impossible to get consent from bloggers to use their research in others work all the time, therefore it should really be up to the blogger them self to assess whether what they are posting in a public space is within their comfort zone to be used by others. If the blogger takes reasonable steps to hide their identity and only post things they are happy with being used again then there should be no need for any code of ethics. 

• Bruckman, A. (2002). Studying the amateur artist: A perspective on disguising data collected in human subjects research on the Internet. Ethics and Information Technology, 4, 217–231.
• Eastham, L. (2011) Research Using Blogs for Data: Public Documents or Private Musings? Research in Nursing & Health, 34, 353–361
• Wilkinson, D. & Thelwall, M. (2010). Researching personal information on the public Web: Methods and ethics, Social Science Computer Review. Available online at http://ssc.sagepub.com/content/early/2010/08/16/0894439310378979 (last accessed 15/05/2013)