Shares in AIM-listed maritime waste treatment provider Nature Group tumbled on Monday morning after the firm revealed that it would miss full-year forecasts.The company stated that the results for the year would be materially below market expectations as a result of the delay in completion of a number of projects and orders together with increased costs associated with preparing for the expansion of the business.The stock was down 26.05% at 22p at 09:56 following the publication of the trading update.The second half of 2012 was adversely affected by a lower-than-expected level of revenue in the company's oil and gas division and decreased margins, the update stated."The deployment and sales of our CTU units are taking longer than previously anticipated and consequently revenue from these units that management had expected to occur in the year ending 2012 are now expected to complete in 2013," the update stated."We had anticipated when building the last two CTU's that they would have been deployed sooner, but it is now apparent that they won't contribute to Nature's 2012 results. As the pipeline of projects for our CTU's is growing, we are still confident that the operational shift within the oil and gas industry, for treating waste offshore instead of onshore, is happening."In spite of challenges, the company reported promising devlopments: "Over the last two years we are extremely pleased by the number of opportunities which have been generated in both existing and new market locations and are actively progressing several of these and we expect to make further announcements in the near future". Nature Group stated that it had signed a contract with the UK Ministry of Defence for the construction of a waste processing facility in an overseas territory with a contract value in excess of £2m."The board is confident of the fundamental long term prospects of the group. Our technology and services are gaining increasing recognition and we are committed to a controlled expansion. Our balance sheet is robust and we still have approximately £1m of net cash, despite our many recent capital expenditures. The company remains committed to its previously announced dividend payout policy," the statement added.On November 13th , the company announced the appointment of a new Chairman and stated in its update that it has since instigated a thorough review of the company structure and reporting lines. MF