Frequently Asked Questions

Why is SAV important?

Submerged aquatic vegetation (SAV), primarily eelgrass (Zostera marina) and widgeon grass (Ruppia maritima), is an important component of the Barnegat Bay-Little Egg Harbor ecosystem, serving as important habitat for benthic epifauna and infauna (aquatic animals living on or within the bottom of the bay). Some organisms graze on SAV (e.g., gastropods, fish, duck, muskrats) and eelgrass also serves as valuable spawning, nursery and feeding grounds for finfish populations. SAV also stabilize the benthic habitat by baffling waves and currents and alleviate substrate erosion. *

* reference at bottom of page

Why study it?  Is the SAV in Barnegat Bay at risk?

Studies were conducted due to the ecological importance of seagrass and recent indications of dieback.  These seagrasses are a sensitive indicator of the bay's overall health. When coastal waters become too turbid due to algae blooms or suspended sediment, seagrass productivity and growth are negatively impacted and can lead to dieback.

Comparison of the earlier maps with the 1990's survey shows an overall decrease of approximately 2,000 to 3,000 hectares in the area of seagrass beds. While there are indications of seagrass decline, due to the great difference in mapping methods used for each of the surveys, we are cautious in directly attributing the decrease in mapped eelgrass acreage to a large-scale dieback.

What affects SAV occurrence and health?

The occurence of SAV species in the bay strongly depends on environmental conditions. Each species has its own requirements for and tolerances of physical characteristics, such as temperature, salinity, sediment composition, water velocity, and turbidity. The temporal and spatial shifts of SAV in the Barnegat Bay ecosystem likely result from naturally occurring cycles although human activities such as dredging, nutrient loading, boating and the use of personal watercraft may be detrimental.*

The impact of increased development within the watershed coupled with the increases in nutrient runoff (leading to overenrichment or eutrophication) has sparked concern about the status of eelgrass (Zostera marina) and other seagrasses in the Barnegat Bay - Little Egg Harbor system.

Barnegat Bay shows a pattern of higher water turbidity as well as greater nutrient loading in the northern sections of the bay which follows the pattern of increased residential and commercial development.

Wasting disease, presumably caused by the protist Labyrinthula zosterae, has been responsible for significant declines of seagrasses during certain years.*

* reference at bottom of page

How were the SAV mapped?

The 'SAV Mapping Methods' section describes the field and aerial surveys conducted by various government

What is GIS? How were the SAV maps used by CRSSA with this technology?

Geographic Information System (GIS) is a technology utilizing digital geographic data and computer software/hardware to map, analyze, model and present spatial information.  In this case, the digital geographic data is submerged aquatic vegetation.

The maps from the 1960's, 1970's, 1980's and 1990's were digitized from their original paper map sources into the GIS.  Once digitized, the maps were analyzed by comparing the different time periods simultaneously; additionally, using other data of turbidity and seagrass depth limits, CRSSA was able to develop a model to predict the distribution of potential seagrass habitat through Barnegat Bay under current and theoretical conditions. These modeled distributions were then compared to the mapped distributions then presented visually using the GIS.

I am a GIS user interested in obtaining the SAV data. Are they available?

Yes, GIS users can download the data from the CRSSA SAV project website
(On the CRSSA home page >> Go to Coastal & Marine >> Go to Submerged Aquatic Vegetation Mapping).

Are these maps suitable for determining the presence or absence of SAV at a particular site location?

These maps, as presented on this web site, provide a regional picture of SAV distribution at various points in time and are not intended for site level permit applications or litigation purposes.  These maps and data, alone, are not sufficient to determine the presence or absence of SAV.  Conclusive evidence concerning the presence or absence of SAV requires site inspections, preferably at several points in time during the SAV growing season.

 

* text extracted from 'The Scientific Characterization of the Barnegat Bay - Little Egg Harbor Estuary and Watershed' produced by the Barnegat Bay Estuary Program

 


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CRSSA SAV web site designed and maintained by CRSSA. Original 2002 web site start-up funding by the New Jersey Department of Environmental Protection (NJDEP) through the Jacques Cousteau National Estuarine Research Reserve (JCNERR) for JCNERR Coastal Decision Maker and education outreach programs; continued web updates with support from CRSSA. SAV site is a segment of CRSSA's Coastal Studies website. Page last updated May 4, 2011.. See front/home SAV page for more credit information.