Pensacola Bay By Lisa Schwenning,1 Traci Bruce,1 and Lawrence R. Handley2 Background during the early to mid-1950s (Northwest Florida Water Management District, 1991). The Pensacola Bay system (fig. 1) has historically Predominant land uses within the riverine watershed supported a rich and diverse ecology, productive fisheries, and include forestry, agriculture, military, and public conservation considerable recreational opportunities. It has also provided and recreation, as well as residential and other urban land uses an important resource for commercial shipping and military around several communities. Much of the economic base of activities and has enhanced area aesthetics and property this area is provided by the extraction of natural resources, values. Unfortunately, for many years, point and nonpoint primarily timber and agriculture, but there are also indirect source pollution, direct habitat destruction, and the cumulative economic benefits provided by military activities and the impacts of development and other activities throughout service sector. Major public landholdings include portions the watershed have combined to degrade the health and of Eglin Air Force Base, Blackwater River State Forest productivity of much of the Pensacola Bay system (Northwest (Northwest Florida Water Management District, 1997), and Florida Water Management District, 1997). water management district lands along the Escambia and During the 1800s and early 1900s, extensive logging Blackwater Rivers. of hardwood trees occurred on tributaries entering the Population growth and development apply the greatest Pensacola Bay system (Rucker, 1990). Historically, it is pressure to the environment of Florida’s coastal areas. likely that the timber industry adversely impacted the upper As population increases, so do the demands on coastal bays of the system. Blackwater Bay and lower reaches of the resources. Over 75% of Florida’s residents live in coastal Blackwater River and Pond Creek were covered with sawdust counties, and a 50% increase is estimated by 2020 (Florida from mills in Bagdad, Fla. Sawn timber and sawdust are Department of Environmental Protection, 1998). In the three rich in turpines and other toxic substances. During logging counties included in the Florida portion of the Pensacola Bay operations, turbidity, nutrient concentrations, biological watershed, there has been a 220% increase in population since oxygen demand, and chemical oxygen demand were probably 1960. As a result of the population increase, there has been a high, and dissolved oxygen levels were probably low. Benthic dramatic change in land use of the Pensacola Bay area from communities may have been scarce or nonexistent while the agricultural to urban. Escambia County alone lost 13,247 ha mills were operating at peak levels (Northwest Florida Water (32,732 acres) of agricultural lands between 1992 and 1997; Management District, 1991). during the same time, the county gained approximately 6,071 Barge traffic and log rafting from tributaries to the Port ha (15,000 acres) of urban land use. of Pensacola unquestionably resuspended fine sediments in shoal areas of the system. Fairly extensive dredging of the Blackwater River was authorized and completed in 1916 Scope of Area by the U.S. Army Corps of Engineers (1990). Moskovits (1955) reported general silting problems in Pensacola Bay The Pensacola Bay system consists of about 50,992 ha during 1949–50, as well as settlement of fouling organisms (126,000 acres), including its coastline of 885 km (550 mi) (barnacles, serpulid worms, hydroids, bryozoans, sponges, and open surface waters of about 373 km2 (144 mi2). The jingle shells, and Mytilus sp.) on artificial substrata. watershed covers nearly 18,130 km2 (7,000 mi2). The final These organisms tend to settle in relatively clear water, outlet for the system is the Gulf of Mexico at the mouth of so the presence of these animals suggests that suspended Pensacola Bay. The watershed of the Pensacola Bay system sediment loads were not sufficient to inhibit the settlement includes many different counties, cities, and incorporations. of zooplankton and that water quality may have been better Approximately 65% of the entire watershed is located outside of Florida State lines; Alabama counties—including portions of Covington, Escambia, Conecuh, Butler, Crenshaw, Pike, 2 1 Florida Department of Environmental Protection, Northwest District. Bullock, Montgomery, and Coffee—make up 11,632 km 2 U.S. Geological Survey. 130 Seagrass Status and Trends in the Northern Gulf of Mexico: 1940–2002 65 r e iv R uh ec on C Interstate highway River Gulf Intracoastal Waterway County line Pensacola Bay Watershed boundary City r e v i R a i b m a r c r R ive s ate E kw c er la iv B R w llo Y e 10 r Ferry Pass e i v y R E a st B a Pensacola Fort Walton Beach Pensacola Bay N km 0 10 20 30 40 Gulf of Mexico mi 0 5 10 15 20 25 Figure 1. Watershed for the Pensacola Bay system. Methodology Employed To Determine and Document Current Status 131 (4,491 mi2) of the Pensacola Bay system (Florida Department Santa Rosa Sound of Environmental Protection, 1998). Approximately 857 km2 (331 mi2) (45%) of Escambia Santa Rosa Sound is oriented west to east and connects County form the western portion of the Pensacola Bay Choctawhatchee and Pensacola Bays. It is bordered on the watershed. Nearly all of the 2,631 km2 (1,016 mi2) of south by Santa Rosa Island and on the north by the Gulf Santa Rosa County, located to the east, are included in the Breeze Peninsula. watershed. Seventy-five percent of Okaloosa County (1,940 km2, or 749 mi2) lies in the watershed. Within Okaloosa County are the Yellow and Shoal Rivers, their tributaries, and the other half of Santa Rosa Sound. Only 648 km2 (250 mi2) Methodology Employed To Determine (20%) of Walton County drain into the Pensacola Bay system and contain a portion of the Shoal River and tributaries. and Document Current Status The western portion of the basin is predominantly urban, whereas the eastern portion is primarily low density, rural, The most current mapping study of seagrass coverage for and undeveloped. the Pensacola Bay area was conducted more than 10 yr ago The Pensacola Bay system has been divided into five by the U.S. Geological Survey (USGS) National Wetlands segments: Escambia Bay, East Bay, Pensacola Bay proper, Big Research Center (NWRC) by using natural-color aerial Lagoon, and Santa Rosa Sound (fig. 2). photography taken in 1992 at a 1:24,000 scale as part of the northeastern Gulf of Mexico seagrass mapping project. The mapping protocol consisted of stereoscopic Escambia Bay photointerpretation, cartographic transfer, and digitization in accordance with strict mapping standards and Escambia Bay may be the most vulnerable of the Pensacola Bay segments. It is located north of the line conventions.Other important aspects of the protocol between Garcon Point to the east and Magnolia Point to the included the development of a seagrass classification west. Escambia Bay is commonly divided into upper and system, groundtruthing, quality control, and peer review. lower parts, with Interstate 10 delineating the boundary. This The information derived from the photography was dividing line falls in an area that divides species between subsequently transferred by using a zoom transfer scope the dominant brackish water plant water celery (Vallisneria onto a stable medium overlaying USGS 1:24,000-scale americana) in the upper bay and the dominant seagrass shoal quadrangle base maps. The primary data source was grass (Halodule wrightii) in the lower part of the bay. 1:24,000-scale natural color aerial photography flown by the National Aeronautics and Space Administration Stennis East Bay Space Center in fall 1992. In those cases where the data were inadequate or incomplete, contemporary supplemental East Bay is located east of the line between Garcon Point data were acquired from other sources and used to complete and Redfish Cove. East Bay, like Escambia Bay, is commonly the photographic coverage. divided into upper and lower segments, but with Robinson The seagrass classification system that was developed Point delineating the boundary. The area north of Robinson (see appendix for full discussion) consisted of two classes of Point harbors all brackish water submerged aquatic vegetation. open water—RIV (riverine, fresh water) and EST (estuarine The area south of Robinson Point, or East Bay proper, contains or marine open water)—and five classes of seagrass habitats. shoal grass and turtle grass (Thalassia testudinum). One seagrass habitat class is continuous seagrass, CSG, for which no density distinction was made. The other four classes Pensacola Bay are patchy seagrass based on percent ground cover of patches in 5% increments: PSG1 (0%–10%, very sparse), PSG2 Pensacola Bay is west of the Garcon Point Bridge. (15%–40%, sparse), PSG3 (45%–70%, moderate), and PSG4 Escambia and East Bays drain into Pensacola Bay, along with (75%–95%, dense). Bayous Texar, Chico, and Grande. Pensacola Bay empties into The groundtruthing phase included the participation of the Gulf of Mexico at the Pensacola Pass. field staff from Gulf Islands National Seashore, U.S. Fish and Wildlife Service, Dauphin Island Sea Lab, Mississippi Big Lagoon State University, Alabama Department of Conservation and Natural Resources, and Florida Department of Environmental Big Lagoon is oriented west to east and connects lower Protection. Draft maps were sent out to these agencies Perdido and Pensacola