The distribution of submerged aquatic vegetation (SAV) in Chesapeake Bay and its tributaries was mapped from black and white aerial photographs. These were taken between May and November 2008, at a scale of 1:24,000, encompassing 173 flight lines.

CHESAPEAKE BAY

For 2008, 31,104 hectares (76,861 acres) of SAV were mapped in Chesapeake Bay and its tributaries.

Notable changes in SAV distribution were measured between 2007 and 2008. SAV increased 18% from 26,271 ha (64,917 ac) in 2007 to 31,104 ha (76,861 ac) in 2008.

SAV increased in all three (Upper, Middle, and Lower) geographic zones delineated for Chesapeake Bay for the first time since 2001. In 2008, SAV increased in 47, decreased in 12, and remained unvegetated in 34 of the 93 CBP segments.

The 4,833 ha increase in total SAV coverage was strongly driven by the following changes. SAV on the Susquehanna Flats (CB1TF1 & CB1TF2) expanded by 1,069 ha, 22% of the baywide increase, which continued the decade long growth. Widgeongrass underwent a major expansion in many areas of the Bay. In particular, the 1,208 ha increase in the Honga River region (HNGMH and CB5MH) and part of the 541 ha increase in the Tangier-Smith Island region (TANMH1 & TANMH2), 442 ha increase in the Eastern Lower Chesapeake Bay (CB7PH), and 726 ha increase in the Mobjack Bay (MOBPH) can be attributed to this species.  In total these areas contributed 60% of the baywide increase. Eelgrass continued its recovery from the 2005 baywide dieback and expanded in the offshore areas of the existing beds to add to the increases in TANMH1, TANMH2, CB7MH, and MOBPH.

Upper Bay Zone

In the Upper Bay Zone (21 CBP segments extending south from the Susquehanna River to the Chester and Magothy rivers), SAV increased 21% from 7,657 ha (18,922 ac) in 2007 to 9,289 ha (22,954 ac) in 2008.

Ten of the 21 segments increased by at least 20% and by at least 5 ha from 2007 totals:

	21%, Northern Chesapeake Bay Segment 1 (CB1TF1), 337 ha (2007) vs. 408 ha (2008)
	21%, Northern Chesapeake Bay Segment 2 (CB1TF2), 4,745 ha (2007) vs. 5,744 ha (2008)
	59%, Northeast River (NORTF), 47 ha (2007) vs. 74 ha (2008)
	70%, Upper Chesapeake Bay (CB2OH), 151 ha (2007) vs. 256 ha (2008)
	50%, Sassafras River Segment 1 (SASOH1), 149 ha (2007) vs. 223 ha (2008)
	1204%, Sassafras River Segment 2 (SASOH1), 2 ha (2007) vs. 21 ha (2008)
	40%, Gunpowder River Segment 1(GUNOH1), 226 ha (2007) vs. 317 ha (2008)
	50%, Middle River (MIDOH), 223 ha (2007) vs. 335 ha (2008)
	53%, Upper Central Chesapeake Bay (CB3MH), 50 ha (2007) vs. 76 ha (2008)
	23%, Lower Chester River (CHSMH), 27 ha (2007) vs. 34 ha (2008)

None of the 21 segments decreased by at least 20% and by at least 5 ha from 2007 totals.

Two of the 21 segments remained unvegetated in 2008.

Middle Bay Zone

In the Middle Bay Zone (44 CBP segments extending south from the Bay Bridge to the Rappahannock River and Pocomoke Sound, and including the Potomac River), SAV increased 15% from 12,137 ha (29,992 ac) in 2007 to 13,970 ha (34,521 ac) in 2008.

Seven of the 44 segments increased by at least 20% and by at least 5 ha from 2007 totals:

	67%, Lower Central Chesapeake Bay (CB5MH), 747 ha (2007) vs. 1,247 ha (2008)
	99%, Honga River (HNGMH), 806 ha (2007) vs. 1,604 ha (2008)
	100%, Fishing Bay (FSBMH), 0 ha (2007) vs. 9 ha (2008)
	45%, Manokin River Segment 1 (MANMH1), 115 ha (2007) vs. 168 ha (2008)
	26%, Big Annemessex River Segment 1 (BIGMH1), 231 ha (2007) vs. 292 ha (2008)
	27%, Lower Pocomoke River (POCMH), 445 ha (2007) vs. 565 ha (2008)
	266%, Middle Patuxent River (PAXOH), 11 ha (2007) vs. 41 ha (2008)

Four of the 44 segments decreased by at least 20% and by at least 5 ha from 2007 totals:

	63%, Mouth of the Choptank River (CHOMH1), 509 ha (2007) vs. 186 ha (2008)
	43%, Little Choptank River (LCHMH), 57 ha (2007) vs. 33 ha (2008)
	82%, Lower Patuxent River Segment 1 (PAXMH1), 15 ha (2007) vs. 3 ha (2008)
	42%, Lower Potomac River (POTMH), 274 ha (2007) vs. 160 ha (2008)

Twenty-one of the 44 segments remained unvegetated in 2008.

Lower Bay Zone

In the Lower Bay Zone (28 CBP segments covering the region south from the Rappahannock River and Pocomoke Sound regions to the mouth of the Bay), SAV increased 21% from 6,476 ha (16,004 ac) in 2007 to 7,845 ha (19,386 ac) in 2008.

Eight of the 28 segments increased by at least 20% and by at least 5 ha from 2007 totals:

	21%, Eastern Lower Chesapeake Bay (CB7PH), 2,078 ha (2007) vs. 2,521 ha (2008)
	44%, Lower Rappahannock River (RPPMH), 171 ha (2007) vs. 247 ha (2008)
	29%, Corrotoman River (CRRMH), 146 ha (2007) vs. 188 ha (2008)
	49%, Upper Rappahannock River (RPPTF), 30 ha (2007) vs. 44 ha (2008)
	25%, Piankatank River (PIAMH), 113 ha (2007) vs. 140 ha (2008)
	29%, Mobjack Bay (MOBPH), 2,503 ha (2007) vs. 3,228 ha (2008)
	26%, Lower York River (YRKPH), 149 ha (2007) vs.187 ha (2008)
	218%, Middle James River (JMSOH), 4 ha (2007) vs. 14 ha (2008)

One of the 28 segments decreased by at least 20% and by at least 5 ha from 2007 totals.

25%, Chickahominy River (CHKOH), 427 ha (2007) vs. 318 ha (2008)

Eleven segments remained unvegetated in 2008.

DELMARVA PENINSULA COASTAL BAYS ZONE

In the Delmarva Peninsula Coastal Bays Zone (Assawoman, Isle of Wight, Sinepuxent, Chincoteague, and Southern Virginia coastal bays), SAV increased 24% from 4,362 ha (10,780 ac) in 2007 to 5,400 ha (32,974 ac) in 2008.

All five of the segments increased since 2007:

	11%, Assawoman Bay (AAWPH), 207 ha (2007) vs. 230 ha (2008)
	34%, Isle of Wight Bay 138 ha (2007) vs.185 ha (2008)
	1%, Sinepuxent Bay (SPXPH), 648 ha (2007) vs. 656 ha (2008)
	20%, Chincoteague Bay (CHNPH), 2,779 ha (2007) vs. 3,346 ha (2008)
	66%, Southern Virginia Coastal Bays (SVCPH), 591 ha (2007) vs.984 ha (2008)

None of the five segments decreased since 2007.