Are there tax implications of earning and transacting in cryptocurrency on the Hive blockchain?

The answer is relevant to the country and state in which you live. Maybe even the municipality. In general, any gain in an asset when realized is a taxable situation. So if you earn value from crypto and then sell the crypto, the difference between where you started and where you ended is taxable. That said, at this time it could be difficult for a taxing authority to be able to track your gain. However, using an exchange with KYC is likely to be trackable and result in taxes due. 

Okay this is one of those cases where, because I have a UK accountancy qualification, I genuinely need to say that my opinion is unofficial and that you should seek advice from your own accountant. 

What I'll do is outline the UK tax position in a simplified form. Other countries may or may not have a similar approach. I'm not going to consider more complex scenarios like withholding tax or the implications if you are an ex-patriate. 

Hive earnings fall into two tax regimes.

1. First is income tax. This covers earnings where you've done actual work to gain the revenue. So for Hive, this means author rewards, curation, Tribe Token tips received in comments.
2. Second is capital gains tax. This covers gains where no direct work was done, so primarily HBD interest, as well as staking rewards, Hive interest and earnings from Tribe mining tokens.

You should also consider whether Hive earnings are a business or not. A key piece of HMRC guidance is that a hobby becomes a business if your turnover exceeds £1000 in any given tax year. This is known as the "trading allowance", but note that it's the total of all side hustles including eBay etc, not per side hustle. If this is the case, you should register as a business with HMRC as soon as you believe your total earnings from side hustles is likely to exceed the threshold.

If your total crypto earnings are under £1000, it's likely to be considered as trivial by HMRC, but definitely check with your own accountant as your other sources of income may be relevant. But be aware that you should not claim costs (crypto fees etc) unless you are also paying tax on the income !

If you are earning enough for it to be relevant for tax purposes, HMRC treats each and every single transaction as a potentially taxable event. To my mind this illustrates their utter failure to comprehend the concept that crypto is often micro-transactional in nature. But it's important to keep good records of each transaction, ideally both as a ledger and with supporting audit trail data (copies of emails, screenshots of transactions, downloaded reports from exchanges etc).