For the record

Moose can cause an elk of a confusion. In our story on reviving ecosystems (1 March, p 40) our usage of the US name elk for the species  also known as the wapiti could have muddled people, considering the article also featured moose (known  as elk in Europe). ■  In having our two cents on anaerobic oceans (22 February, p 12), we claimed researchers lowered the oxygen level in their aquarium to  “200 times below the amount currently found in the air”. We should have said one two-hundredth. ■  We shorted the market in our article on lunar delivery (22 February, p 6): the true value lies between $3.1 and $9.7 billion. ■  A house divided: in our feature on New Zealand’s drug decriminalisation (8 March, p 40), we describe the legislature as having two chambers.  It has been unicameral since 1951