Mapping and Monitoring of Submerged Aquatic Vegetation in Escambia-Pensacola Bay System, Florida

Abstract

Recently, the distribution and changes in submerged aquatic vegetation (SAY) in the Escambia-Pensacola Bay System in northestern Florida were monitored by two techniques. One technique used divers to measure changes in the deepwater margin of beds and provided horizontal growth measurements to the nearest centimeter, the other used a differential global positioning system (DGPS) on a small boat to map the perimeter of SAY beds in shallow water. Current distribution of SAY in Escambia Bay shows that most of the SAY losses that occurred during the 1950s to 1970s have been recovered. In Santa Rosa Sound and Pensacola Bay, SAY showed significant increased growth with horizontal growth rates of some beds averaging more than 50 em over the past year. In Big Lagoon, however, SAY has declined an average of 10 em in horizontal coverage along the deepwater edge. Water quality and photosynthetically active radiation light measurements from the Escambia-Pensacola Bay System suggest that increased light availability was associated with the increased seagrass coverage in Santa Rosa Sound and Pensacola Bay, and elevated nutrient concentrations were associated with the seagrass declines in Big Lagoon.

Estuarine Nutrient Criteria: An Effects Based Approach

“…The area in upper Escambia Bay where bottom light levels are ≥20% is calculated as 3.8 km 2 , which is similar to the seagrass bed area estimate of 1.5 km 2 observed in 1992 (Lores et al, 2000;Lores and Sprecht, 2001). The area in upper Escambia Bay where bottom light levels are ≥20% is calculated as 3.8 km 2 , which is similar to the seagrass bed area estimate of 1.5 km 2 observed in 1992 (Lores et al, 2000;Lores and Sprecht, 2001).…”

Seagrass Distribution in the Pensacola Bay System, Northwest Florida

“…In a detailed study conducted in these areas (Heck et al 1996), seagrasses declined during 1993 -1995 in both areas due to a combination of propeller scarring, reduced water clarity, changes in salinity and burial due to hurricanes. Lores et al (2000) reported seagrass coverage was also decreasing in Big Lagoon during 1997 and 1998.…”

“…The numerous seagrass investigations conducted in the PBS have been temporally and spatially inconsistent and research methodologies have varied. Seagrass mapping has been the focus of most studies, and only limited information is available describing physiological and morphological parameters of plant condition such as above-and belowground biomass, shoot density, blade height and epiphyte/ biomass ratio, which have been reported for grasses in Big Lagoon, Santa Rosa Sound and Escambia River delta region (Heck et al 1996, Lores et al 2000, FDEP 2001.…”

“…3,858 1,894 1,814 1,654 historical maximum occuring in 1992 followed by a 75% decline in 2003. Lores et al (2000) reported increased coverage of V. americana near the Escambia River delta for 1997 and 1998 relative to 1992, but coverage decreased during 2000 due to drought and high salinity (Lores and Sprecht 2001). Although continuous seagrass coverage in Pensacola Bay was not detectable in 2003, patchy coverage increased from 101 ha to 151 ha since 1992.…”

Mesohaline Submerged Aquatic Vegetation Survey Along the U.S. Gulf of Mexico Coast, 2000: A Stratified Random Approach

“…Although SAV distributions in some regions of the Gulf have been reported (e.g., Iverson and Bittaker, 1986;Handley et al, 2007;Mills et al, 2008), to date (Appendix) there has been no comprehensive Gulf-wide survey of mesohaline (5-20 ppt) SAV distribution. Most SAV studies in the Gulf have focused on marine SAV (seagrasses and macroalgae) that occur in large beds in clear waters near beaches, barrier islands, and open bays (Continental Shelf Associates, Inc., and Martel Laboratories, Inc., 1985;Lores et al, 2000). These seagrass beds are the SAV habitat reported in estimates of the nation's natural resources (e.g., Duke and Kruczynski, 1992;Mattson, 1999).…”