SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

SCHEDULE 13G

(Rule 13d-102)

Information To Be Included In Statements Filed Pursuant To § 240.13d-1(b), (c) And (d) And Amendments Thereto

Filed Pursuant To § 240.13d-2

Under The Securities Exchange Act Of 1934

(Amendment No. 6)

Cyanotech Corporation

(Name of Issuer)

Common Stock

(Title of Class of Securities)

232437-301

(CUSIP Number)

December 31, 2012
(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

¨ Rule 13d-1(b)

x Rule 13d-1(c)

¨ Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act, but shall be subject to all other provisions of the Act (however, see the Notes).

* Based on 5,463,938 total shares outstanding on February 6, 2013 as reported in the Issuer's Form 10-Q for the quarterly period ended December 31, 2012.

* Based on 5,463,938 total shares outstanding on February 6, 2013 as reported in the Issuer's Form 10-Q for the quarterly period ended December 31, 2012.

* Based on 5,463,938 total shares outstanding on February 6, 2013 as reported in the Issuer's Form 10-Q for the quarterly period ended December 31, 2012. 

* Based on 5,463,938 total shares outstanding on February 6, 2013 as reported in the Issuer's Form 10-Q for the quarterly period ended December 31, 2012.

Item 1.

Cyanotech Corporation.

73-4460 Queen Kaahumanu Highway, Suite 102

Kailua-Kona, Hawaii 96740

Item 2.

This statement is filed jointly by Michael A. Davis ("Davis"), the Michael Arlen Davis Charitable Lead Annuity Trust (the "Charitable Trust"); Davis' spouse, Janet J. Johnstone ("Johnstone") and the Michael Arlen Davis Revocable Trust (the "Revocable Trust").

1621 Juanita Lane

Tiburon, California 94920

United States

Common Stock.

232437-301

Item 3.   If this statement is filed pursuant to Rule 13d-1(b) or 13d-2(b), check whether the person filing is a:

N.A.

Item 4.   Ownership.

Provide the following information regarding the aggregate number and percentage of the class of securities of the Issuer identified in Item 1.

Davis: 1,085,932 shares.

Johnstone: 130,013 shares .

Charitable Trust: 480,769 shares.

Revocable Trust: 325,150 shares.

Davis: 19.9%

Johnstone: 2.4%

Charitable Trust: 8.8%

Revocable Trust: 6.0% 

Davis: 0 shares.

Johnstone: 0 shares.

Charitable Trust: 480,769 shares.

Revocable Trust: 325,150 shares. 

Davis: 1,085,932 shares. The 1,085,932 shares consist of: 48,013 shares held by Davis; 31,250 shares held by Johnstone; 150,000 shares held by the Children's Trusts; 50,000 shares held by the Custodial Accounts; 480,769 shares held by the Charitable Trust; 750 shares held by the Family Trust and 325,150 shares held by the Revocable Trust.

Johnstone: 130,013 shares. The 130,013 shares consist of: 31,250 shares held by Johnstone; 48,013 shares held by Davis; 50,000 shares held by the Custodial Accounts; and 750 shares held by the Family Trust.

Charitable Trust: 0 shares.

Revocable Trust: 0 shares.

Davis: 0 shares.

Johnstone: 0 shares.

Charitable Trust: 480,769 shares.

Revocable Trust: 325,150 shares.

Davis: 1,085,932 shares. The 1,085,932 shares consist of: 48,013 shares held by Davis; 31,250 shares held by Johnstone; 150,000 shares held by the Children's Trusts; 50,000 shares held by the Custodial Accounts; 480,769 shares held by the Charitable Trust; 750 shares held by the Family Trust and 325,150 shares held by the Revocable Trust.

Johnstone: 130,013 shares. The 130,013 shares consist of: 31,250 shares held by Johnstone; 48,013 shares held by Davis; 50,000 shares held by the Custodial Accounts; and 750 shares held by the Family Trust.

Charitable Trust: 0 shares.

Revocable Trust: 0 shares.

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent (5%) of the class of securities, check the following x*.

*Johnstone has ceased to be the beneficial owner of more than 5% of the class of securities. Each of Davis, the Charitable Trust and the Revocable Trust continue to own more than 5% of the class of securities.

Wilmington Trust Corporation is Co-Trustee of the Children’s Trusts and the Charitable Trust, and collectively holds 630,769 shares or 11.5% of the class of stock.

N.A.

N.A.

N.A.

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under §240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: February 14, 2013

ATTENTION: INTENTIONAL MISSTATEMENTS OR OMISSIONS OF FACT CONSTITUTE FEDERAL
CRIMINAL VIOLATIONS (SEE 18 U.S.C. 1001)

EXHIBIT INDEX

Ex.

1      Joint Filing Agreement

2      Limited Power of Attorney of the Michael Arlen Davis Revocable Trust

This filing hereby incorporates by reference the Limited Powers of Attorney for Section 13 Reporting Obligations filed as Exhibit 1 to Amendment 4 to this Schedule 13G filed on February 14, 2011.

Exhibit 1

Agreement of Joint Filing

In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, the undersigned, Michael A. Davis, Janet J. Johnstone, the Michael Arlen Davis Charitable Lead Annuity Trust, and the Michael Arlen Davis Revocable Trust hereby agree to the joint filing on behalf of each of them of the Schedule 13G to which this Agreement is attached as an exhibit (and any further amendment filed by them) with respect to the common stock, $0.02 par value, of Cyanotech Coporation.

This Agreement may be executed simultaneously in any number of counterparts, all of which together shall constitute one and the same instrument.

Dated: 2/10/13

Exhibit 2

LIMITED POWER OF ATTORNEY

FOR

SECTION 13 REPORTING OBLIGATIONS

                  Know all by these presents, that the undersigned hereby makes, constitutes and appoints each of Sara Finigan, Todd Hovey and Eleanor Hicks, each acting individually, as the undersigned’s true and lawful attorney-in-fact, with full power and authority as hereinafter described on behalf of and in the name, place and stead of the undersigned to:

          (1)    prepare, execute, acknowledge, deliver and file Schedules 13D and 13G (including any amendments thereto or any related documentation) with the United States Securities and Exchange Commission and any national securities exchanges, as considered necessary or advisable under Section 13 of the Securities Exchange Act of 1934 and the rules and regulations promulgated thereunder, as amended from time to time (the “Exchange Act”); and

          (2)    perform any and all other acts which in the discretion of such attorney-in-fact are necessary or desirable for and on behalf of the undersigned in connection with the foregoing.

                  The undersigned acknowledges that:

          (1)  this Limited Power of Attorney authorizes, but does not require, each such attorney-in-fact to act in their discretion on information provided to such attorney-in-fact without independent verification of such information;

          (2)  any documents prepared and/or executed by any such attorney-in-fact on behalf of the undersigned pursuant to this Limited Power of Attorney will be in such form and will contain such information and disclosure as such attorney-in-fact, in his or her discretion, deems necessary or desirable;

          (3)  the attorneys-in-fact do not assume (i) any liability for the undersigned’s responsibility to comply with the requirements of the Exchange Act or (ii) any liability of the undersigned for any failure to comply with such requirements; and

          (4)  this Limited Power of Attorney does not relieve the undersigned from responsibility for compliance with the undersigned’s obligations under the Exchange Act, including without limitation the reporting requirements under Section 13 of the Exchange Act.

                The undersigned hereby gives and grants each of the foregoing attorneys-in-fact full power and authority to do and perform all and every act and thing whatsoever requisite, necessary or appropriate to be done in and about the foregoing matters as fully to all intents and purposes as the undersigned might or could do if present, hereby ratifying all that each such attorney-in-fact of, for and on behalf of the undersigned, shall lawfully do or cause to be done by virtue of this Limited Power of Attorney.

                This Limited Power of Attorney shall remain in full force and effect until revoked by the undersigned in a signed writing delivered to each such attorney-in-fact.

          IN WITNESS WHEREOF, the undersigned has caused this Limited Power of Attorney to be executed as of this 10th day of February, 2013.