Sarasota Bay with tributaries

Science & Technical Projects

Seagrasses

Dr. Jay LeveroneMapping seagrasses in Sarasota Bay is a detailed process that consists of interpreting seagrass signatures from high-resolution aerial photographs and delineating these signatures as seagrass polygons on maps of the Bay. Aerial photographs are acquired more or less every two years enabling scientists to look for changes in seagrass coverage over time. Seagrass coverage maps are developed by delineating areas of seagrass that encompass a minimum area of ~20 hectares. Each seagrass polygon is categorized as either patchy (> 10% and < 25% cover) or continuous (> 25% cover) based on how much seagrass exists within individual polygons.

While this information is valuable for looking at seagrass trends on a large scale, fine scale analyses on the condition of seagrasses are not possible from this protocol. The number of seagrass patches within a polygon is not considered, thus no information is available for ranking polygons beyond either a “patchy” or “continuous” category. The type of seagrass (i.e., turtle, manatee, or shoal grass) cannot be identified at this level of resolution either, so historical shifts in seagrass species composition cannot be reconstructed.

Because of these limitations, SBEP supported a research project by Mote Marine Laboratory to identify, evaluate, and assess changes in seagrass areal extent within the bay, with special attention given to seagrass polygons that have shifted categories (from patchy to continuous or from continuous to patchy). The research was designed to examine whether areas where seagrass polygons have been recorded had undergone changes, either increases or decreases in seagrass cover over time. This research is ongoing.

Bay Scallops

One of the SBEP technical objectives is to restore and enhance shellfish populations and their habitats. Bay scallop populations have declined over the past several decades throughout Florida, including Sarasota Bay. Fifty years ago, thousands of pounds of scallop meats were landed along the Florida Gulf coast; today it is difficult to find any scallops in these same estuaries. This led to drastic changes in the way scallops were managed in state waters. In 1994, waters south of the Suwannee River were closed to harvest while recreational limits statewide were reduced. This also marked the end to commercial bay scallop fishing in Florida. Through a combination of restoration and management practices, the recreational fishery was re-opened in west central Florida, but still remains closed in Sarasota Bay.

The first bay scallop restoration project in Sarasota Bay was sponsored by the SBEP in 1993. This project, initiated by Dr. Jay Leverone, then working for Mote Marine Laboratory, indicated that scallops could be spawned in certain areas of Sarasota Bay. SBEP subsequently sponsored efforts by Dr. Leverone to reestablish a natural breeding population of bay scallops in Sarasota Bay in 1999. Seventy scallops were collected from Sarasota Bay and spawned in the laboratory by the University of South Florida. Subsequently, approximately 20,000 juvenile scallops were transferred to Sarasota for deployment, monitoring and maintenance in the field.

SBEP has budgeted funds for scallop restoration for the current fiscal year as part of its ongoing efforts to restore shellfish populations and their habitats. Dr. Leverone, now the SBEP Staff Scientist continues to lend his expertise to regional shellfish restoration and recovery efforts based on many years of education, laboratory and field research during his tenure at Mote Marine Laboratory.

Dr. Leverone and his colleagues from FWRI have developed a promising method of restoration designed to rebuild local scallop populations. The approach involves the participation of shellfish hatcheries and improved husbandry practices, leading to increased production of healthy, viable scallop larvae. These larvae are the principal restoration unit. The scallop larvae are released into the estuary under specific, controlled conditions just prior to metamorphosis and settlement, usually 8-10 days after hatching. The ability to assess the effectiveness of releasing larvae as well as monitoring the entire restoration process has been enhanced by improvements in the design of our release strategy. The larvae are transferred to temporary in situ enclosures, thereby establishing a marked location where the released scallops can be found during subsequent monitoring. The current restoration strategy circumvents the higher costs and intense labor commitments associated with more traditional restoration approaches that use adults and juveniles as restoration units.

Scallop LarvaeThe initial test of this larval release method was conducted in Pine Island Sound in southwest Florida during 2003. Larval settlement was readily detected shortly after the larvae were released. Numerous juvenile scallops were also detected at the release site three months later, and adult densities were 100 times higher at the release site nine months following larval release. Even more promising was the discovery of dramatically higher adult scallops near the release site the following year. As a direct result of this project, Pine Island Sound had the highest bay scallop density in the entire state that year.

This improved approach to scallop restoration has been adopted throughout the region including projects in Tampa Bay and Sarasota Bay. It has also been repeated in Pine Island Sound.

Fisheries Independent Monitoring (FIM) Program

The Fisheries-Independent Monitoring (FIM) program is a statewide, long-term program designed to monitor the relative abundance of Florida’s fisheries resources. This program, developed, conducted and managed by the Florida Fish and Wildlife Research Institute (FWRI), has three major goals: 1) address the critical need for effective assessment techniques for an array of species and sizes of fishes and selected invertebrates, 2) provide timely information for use in management plans, and 3) monitoring trends in the relative abundance of fishes and selected invertebrates in a variety of estuarine and marine systems throughout Florida.

The FIM program has been in existence since the late 1980s. Over the years, program staff have developed standardized sampling techniques to collect fish and invertebrates in many of the state’s estuaries, tidal rivers and coastal areas. Because the FIM database is long-term, is based on a standardized sampling with a variety of techniques, and covers a broad geographic area, researchers at FWRI and other organizations find it useful for a variety of scientific and management purposes. Some of these purposes include preparation of species inventories, documentation of a particular species’ habitat and dietary requirements, fish and estuarine health, development of ecosystem models, and assessment of the implications of water-resource management actions.

SBEP is well-positioned to help monitor fish and selected invertebrate populations in Sarasota Bay. Visit the Technical Publications page to see the FIM Program year 1-4 reports. Please contact Dr. Jay Leverone at jay@sarasotabay.org for more information.

Aquaculture

The broad term aquaculture refers to the breeding, rearing, and harvesting of plants and animals in all types of water environments, including ponds, rivers, lakes, and the ocean. Similar to agriculture, aquaculture can take place in the natural environment or in a manmade environment. Using aquaculture techniques and technologies, researchers and the aquaculture industry are growing, producing, culturing, and farming all types of freshwater and marine species.

Aquaculture is the fastest growing form of food production in the world. It is also a significant source of protein for people in many countries, including the United States. Globally, nearly half the fish consumed by humans is produced by fish farms. This worldwide trend toward aquaculture production is expected to continue. At the same time, demand for safe, healthy seafood is also expected to grow.

For more information visit the following links:

Consumption Advisory

Seafood Watch is a program of the renowned Monterey Bay Aquarium designed to raise consumer awareness about the importance of buying seafood from sustainable sources. Seafood Watch’s mission is to empower consumers and businesses to make choices for healthy oceans. They recommend which seafood to buy or avoid, helping consumers to become advocates for environmentally friendly seafood. They’re also partners of the Seafood Choices Alliance where, along with other seafood awareness campaigns, they provide seafood purveyors with recommendations on seafood choices.

ResearchMacroalgae

Blooms of red drift macroalgae have emerged along southwest Florida’s coastline, including Sarasota Bay. Most residents are more familiar with toxic algal blooms, or “red tides”, which can cause, among other things, massive fish kills, shellfish contamination, and human respiratory and other health problems.

Unlike red tides, macroalgal blooms lack direct toxicity but have a broader range of ecological impacts. Macroalgal blooms can result in the displacement of native species, habitat destruction, oxygen depletion, alteration of trophic structure and biogeochemical cycles, and seagrass die-off. Because the causes and effects of macroalgal blooms are similar in many ways to those associated with toxic phytoplankton species, the scientific community employs the term “harmful algal bloom” (HAB) to describe this diverse array of bloom phenomena.

A study is being undertaken by Dr. Brian Lapointe of Reef Research & Design, to better understand the taxonomic composition and ecology of macroalgal HABs impacting on Sarasota Bay.

Red Tides

Red tides, a type of harmful algal bloom (HAB), are a natural phenomenon in coastal ecosystems, but human activities are thought to contribute to their increased frequency. Public interest in the social and economic impacts of extended red tide blooms, and questions about the possible role of elevated nutrient supplies from man-made sources, have added a new dimension to the study of Karenia brevis, the organism that causes local red tides.

SBEP is doing its part to contribute to this knowledge by supporting research at Mote Marine Laboratory that addresses the nutrient dynamics during the progress of a bloom of Karenia brevis in Sarasota Bay. The ability of Karenia brevis to utilize urea as a nitrogen source, and the recent incorporation of this compound in fertilizers is of particular interest in current research. This study is helping to understand phytoplankton nutrient dynamics by quantifying the entire suite of nitrogen compounds that may be influencing blooms. Additional analysis includes silica, a necessary nutrient for diatoms, and photosynthetic pigments to follow the progression of phytoplankton communities over time.

Soil Compaction

How do today’s home construction practices affect the characteristics of the soils that will be landscaped once construction is completed and all the heavy equipment is removed?

To answer this question and others, SBEP worked with Dr. Sudeep Vyapari, an expert at the University of Florida focused on environmental horticulture and urban landscape management. Dr. Vyapari and colleagues studied the effects of single family home construction practices on urban soil compaction in Sarasota and Manatee Counties. They used a variety of sophisticated equipment to measure such parameters as soil penetration resistance, dry density and gravimetric water content.

Forty-seven randomly selected locations were chosen to evaluate residential soil compaction. Three different urban landscapes were selected: 1) new houses (less than 5 years old), medium aged houses (6-15 years old, and older houses (more than 15 years old). In addition to the field survey, soil compaction was recorded on twenty randomly selected undisturbed areas and ten commercial areas. A survey was conducted of homeowners and landscapers to assess landscape use practices.

The greatest difference between home sites was found in the first 40 cm of soil depth. Within the top eleven cm, penetration resistance was significantly higher in new and intermediate houses compared with older houses. To a lesser degree, this same relationship was found at intermediate soil depths between 12 and 34 cm. Below 34 cm; soils from each house site had a similar degree of penetration resistance.

In terms of dry density levels, new sites had the highest values, followed by middle-aged sites and older sites. During the rainy season, however, the dry density values from all three treatment sites were similar.

This kind of study can help the construction industry improve development and building practices that reduce the amount of soil compaction. This, in turn, will improve the ability of these soils to retain water and allow newly planted vegetation and turf to take hold.