The distribution of submerged aquatic vegetation (SAV) in Chesapeake Bay, its tributaries, and the Maryland and Virginia coastal bays of the Delmarva Peninsula, was mapped from black and white aerial photographs. These were taken between June and November 2005, at a scale of 1:24,000, encompassing 173 flight lines.
CHESAPEAKE BAY
For 2005, 31,671 hectares (78,262 acres) of SAV were mapped in Chesapeake Bay and its tributaries.
However, in 2005 a portion of the Bay was not flown due to adverse weather in the spring and summer; therefore, portions of the James River were not fully mapped in 2005.
In order to ensure a valid analysis of change in SAV distribution and abundance given the reduced region mapped in 2005, all direct comparisons to 2004 in the report are restricted to only those regions that were mapped in both years. For comparison purposes, partial totals for 2004 have been computed for CBP segments, Bay zones, and the entire Bay using only those regions mapped for both years.
Notable changes in SAV distribution were measured between 2004 and 2005. SAV increased 7% from 29,489 hectares (72,870 ac) in 2004 to 31,671 (78,262 ac) in 2005 in the regions mapped for both years.
SAV increased in two (Middle and Lower) and decreased in one (Upper) geographic zones delineated for Chesapeake Bay. In 2005, SAV increased in 35, decreased in 20, and remained unvegetated in 21 of the 78 CBP segments (Table 6). Two of the segments were not mapped.
Upper Bay Zone
In the Upper Bay Zone (17 CBP segments extending south from the Susquehanna River to the Chester and Magothy rivers), SAV decreased 10% from 8,771 ha (21,674 ac) in 2004 to 7,877 ha (19,464 ac) in 2005.
Three of the 17 segments increased by at least 20% and by at least 5 ha from 2004 totals (Table 6). These segments were:
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26%, Bohemia River (BOHOH), 371 ha (2005) vs. 295 ha (2004) |
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38%, Patapsco River (PATMH), 113 ha (2005) vs. 82 ha (2004) |
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5146%, Middle Chester River (CHSOH), 92 ha (2005) vs. 2 ha (2004) |
Six of the 17 segments decreased by at least 20% and by at least 5 ha from 2004 totals (Table 6).
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29%, Bush River (BSHOH), 294 ha (2005) vs. 414 ha (2004) |
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28%, Gunpowder River (GUNOH), 701 ha (2005) vs. 968 ha (2004) |
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32%, Middle River (MIDOH), 184 ha (2005) vs. 271 ha (2004) |
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100%, Back River (BACOH), 0 ha (2005) vs. 12 ha (2004 ) |
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38%, Upper Central Chesapeake Bay (CB3MH), 229 ha (2005) vs. 368 ha (2004) |
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37%, Lower Chester River (CHSMH), 187 ha (2005) vs. 296 ha (2004) |
Middle Bay Zone
In the Middle Bay Zone (34 CBP segments extending south from the Bay Bridge to the Rappahannock River and Pocomoke Sound, and including the Potomac River), SAV increased 17% from 13,642 ha (33,711 ac) in 2004 to 16,016 ha (39,577 ac) in 2005.
Eleven of the 34 segments increased by at least 20% and by at least 5 ha from 2004 totals (Table 6). These segments include:
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52%, Lower Central Chesapeake Bay (CB5MH), 1,369 ha (2005) vs. 903 ha (2004) |
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28%, Honga River (HNGMH), 1,771 ha (2005) vs. 1,388 ha (2004) |
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27%, Tangier Sound (TANMH), 4,385 ha (2005) vs. 3,456 ha (2004) |
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41%, Manokin River (MANMH), 166 ha (2005) vs. 118 ha (2004) |
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29%, Big Annemessex River (BIGMH), 287 ha (2005) vs. 222 ha (2004) |
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53%, Lower Pocomoke River (POCMH), 723 ha (2005) vs. 471 ha (2004) |
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48%, Upper Patuxent River (PAXTF), 131 ha (2005) vs. 89 ha (2004) |
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21%, Middle Potomac River (POTOH), 1,827 ha (2005) vs. 1,511 ha (2004) |
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87%, Upper Potomac River (POTTF), 1,815 ha (2005) vs. 972 ha (2004) |
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28%, Mattawoman Creek (MATTF), 312 ha (2005) vs. 243 ha (2004) |
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49%, Piscataway Creek (PISTF), 306 ha (2005) vs. 205 ha (2004) |
Five of the 34 segments decreased by at least 20% and by at least 5 ha from 2004 totals (Table 6). These segments were:
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26%, Eastern Bay (EASMH), 311 ha (2005) vs. 421 ha (2004) |
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39%, Mouth of Choptank River (CHOMH1), 928 ha (2005) vs. 1,527 ha (2004) |
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79%, Little Choptank River (LCHMH), 105 ha (2005) vs. 494 ha (2004) |
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78%, South River (SOUMH), 4 ha (2005) vs. 19 ha (2004) |
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100%, Lower Patuxent River (PAXMH), 0 ha (2005) vs. 17 ha (2004) |
Eleven of the 34 segments remained unvegetated (Table 6).
Lower Bay Zone
In the Lower Bay Zone (27 CBP segments covering the region south from the Rappahannock River and Pocomoke Sound regions to the mouth of the Bay), 7,778 ha (19,221 ac) of SAV were mapped for 2005. However, portions of the James River were not mapped for 2005. Comparing the same mapped regions between 2004 and 2005, SAV increased 10% from 7,076 ha (17,486 ac) in 2004 to 7,778 ha (19,220 ac) in 2005.
Nine of the 34 segments increased by at least 20% and by at least 5 ha from 2004 totals (Table 6). These segments include:
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32%,Western Lower Chesapeake Bay (CB6PH), 260 ha (2005) vs. 198 ha (2004) |
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507%, Lower Rappahannock River (RPPMH), 80 ha (2005) vs. 13 ha (2004) |
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30%, Corrotoman River (CRRMH), 118 ha (2005) vs. 91 ha (2004) |
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242%, Upper Rappahannock River (RPPTF), 33 ha (2005) vs. 10 ha (2004) |
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27%, Piankatank River (PIAMH), 227 ha (2005) vs. 179 ha (2004) |
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65%, Upper Mattaponi River (MPNTF), 120 ha (2005) vs. 72 ha (2004) |
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75%, Upper Pumunkey River (PMKTF), 237 ha (2005) vs. 135 ha (2004) |
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61%, Chickahominy River (CHKOH), 282 ha (2005) vs. 175 ha (2004) |
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355%, Upper James River (JMSTF), 22 ha (2005) vs. 5 ha (2004) |
One of the 27 segments decreased by at least 20% and by at least 5 ha from 2004 totals (Table 6). This segment was:
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27%, Middle York River (YRKPH), 177 ha (2005) vs. 242 ha (2004) |
Ten segments remained unvegetated in 2005 (Table 6).