Eelgrass in the South Shore Estuary Reserve

Eelgrass meadows are some of the most biodiverse habitats on Earth, even more diverse than coral reefs and rainforests, supporting many different species. ¹  Eelgrass provides shelter for finfish and shellfish to live, reproduce, and hide from predators. Species that use eelgrass include seahorses, bay scallops, finfish (e.g., tautog, summer flounder, and black sea bass), sea turtles and birds. Many marine species also use eelgrass meadows as a “nursery” or safe space for young fishes and invertebrates, such as juvenile scallops called “spat.”

 ¹  _{Cornell Cooperative Extension of Suffolk County. (2017).  Eelgrass as a habitat .} 

 _{This image illustrates the many important relationships that different marine species have with eelgrass meadows. Symbols for this graphic were obtained courtesy of the  Integration and Application Network, University of Maryland Center for Environmental Science .} 

Human activities such as the burning of fossil fuels and the clearing of forests contribute greatly to the amount of carbon dioxide (CO ₂ ) in Earth’s atmosphere. Carbon dioxide is a naturally occurring component of Earth’s atmosphere, but when it is present in large amounts it can contribute to warming global temperatures and ocean acidification. Eelgrass meadows help mitigate climate change by absorbing carbon from the atmosphere and storing it in sediments. ²  One acre of seagrass is capable of absorbing and storing up to 740 pounds of carbon per year, the amount of carbon emitted by a car driving 3,860 miles per year. ^{3      2}  _{NOAA. What is Blue Carbon?  National Ocean Service website , 07/24/19.}    ³  _{Reynolds, Pamela L. (2018, April).  Seagrass and Seagrass Beds .} 

 _{Image citations:}  

 _{National Science Foundation. (2012, May 21).  Seagrasses Can Store as Much Carbon as Forests .} 

 _{Postlethwaite, V. R.; McGowan, A. E.; Robinson, C.; Kohfeld, K. E.; Pellatt, M. G.; Yakimishyn, J.; Chastain, S. G. (December 2016).  Assessing Carbon Storage and Sequestration of Seagrass Meadows on the Pacific Coast of Canada . Fall Meeting of the American Geophysical Union, San Francisco, CA.} 

 _{Reynolds, Pamela L. (2018, April).  Seagrass and Seagrass Beds .} 

The SSER supports the highest density of recreational boating in the State. The seafood and sportfishing industries on Long Island play an important role in the local economy, and eelgrass plays a key role in the success of these industries. Many commercially valuable species including fluke, tautog, flounder, bass, porgy, blue crab, squid, hard clams, and lobster rely on eelgrass meadows as habitat at some stage in their life cycle. The presence of healthy eelgrass meadows is important for the survival of these commercially valuable species that support Long Island’s $2.5 billion ocean-related economy and tourism. ⁴ 

 ⁴   _{National Oceanic and Atmospheric Administration (NOAA). Economics: National Ocean Watch (ENOW) Data. Based on data from the Bureau of Labor Statistics and the Bureau of Economic Analysis. Charleston, SC: NOAA Office for Coastal Management.}  

 _{Click or pinch to zoom into the map and click on the legend widget to expand the legend.}  

  _{Open in map viewer}  

Plants, including seagrasses, need nutrients to grow. Without sufficient nutrients available in a system, eelgrass cannot grow. However, excess nutrient input into the water from human-related sources, including outdated septic systems and fertilizer runoff, can fuel the growth of microalgae, macroalgae (seaweed) and other organisms that grow on seagrass (such as epiphytes), often leading to harmful algal blooms. The harmful algal blooms and increased growth in seaweed and epiphytes reduce the amount of sunlight reaching the bay bottom. Without sunlight available, eelgrass cannot photosynthesize, growth will slow down, and eelgrass will begin to die off. In addition to limiting the sunlight reaching the bay bottom, epiphytes and seaweed can smother seagrass plants which also limits their ability to photosynthesize.

 _{While too few nutrients prevent eelgrass from growing, too many nutrients can lead to loss of eelgrass.}  

Hardening of shorelines through the construction or reconstruction of seawalls, bulkheads, groins, jetties, breakwaters, boat ramps, boat docks, boat slips and other human-made coastal structures can contribute to the loss of eelgrass meadows. When waves hit natural shorelines, wave energy is absorbed and dispersed. When waves hit hardened shorelines, energy is reflected off hard structures back into the water and can damage or eliminate eelgrass (and other types of SAV) in the nearshore environment. Docks can shade eelgrass, reducing sunlight needed for photosynthesis, and boat ramps, docks, and slips increase the likelihood of boating-related impacts on eelgrass.

Boating in shallow waters can cause propeller scarring, or “prop scars," in seagrass meadows when eelgrass blades are directly cut, or entangled in and uprooted, by boat engine propellers. Boats can also damage eelgrass meadows when they run aground or hit the bay bottom, or in the process of dropping, setting, and retrieving anchors over seagrass unintentionally destroying plants, breaking up continuous eelgrass meadows, and directly reducing eelgrass survival. Resuspension of sediments caused by the wake of motorboats may also scour seagrass plants and create turbidity, reducing the light they require for photosynthesis. ⁶ 

Shellfish harvesting activities (e.g., dredging and raking) can also pose both direct and indirect risks to eelgrass. Dredges can rip up eelgrass beds and lower the level of light penetration by kicking up sediments and negatively effecting water clarity when they are dragged along the bay bottom. Impacts from these activities can be prevented by avoiding areas with eelgrass, trimming boat propellers, and drifting or poling when in eelgrass areas.

 ⁶  _{Crawford, R. E. (2002). Secondary wake turbidity from small boat operation in a shallow sandy bay. Journal of Coastal Research, 50–65.}  

 _{Prop scars in seagrass in Sinepuxent Bay in Coastal Maryland.}  

In 2006, the NYS DEC was tasked to organize and chair an interagency Seagrass Task Force to discuss the state of seagrass and outline recommendations for its protection, management, and restoration. Following the completion of the  Final Report of the New York State Seagrass Task Force: Recommendations to the New York State Governor and Legislature  in 2009, regulations were modified to improve the DEC’s ability to regulate activities in and around SAV beds.

 _{This image shows a bayman clamming in eelgrass in the South Shore Estuary Reserve.} 

The eelgrass program within Cornell Cooperative Extension (CCE) of Suffolk County’s Marine Program works to restore and monitor eelgrass across Long Island. This program tracks the health and extent of existing eelgrass meadows, conducts restoration, develops restoration techniques and models to increase restoration success, and works to expand public understanding of the importance of eelgrass on Long Island. CCE also operates the  Marine Meadows program , a citizen science program where the public can volunteer and assist with eelgrass restoration efforts by helping to assemble planting units.

 Dr. Brad Peterson’s lab  researches threats and stressors to seagrass in New York’s marine waters. Research includes:

• Stressors on seagrass ecosystems
• Seagrass-animal interactions
• Seagrass landscape ecology
• Restoration ecology
• Introduced and exotic marine species
• Climate Change and ocean acidification

 _{A student from the SoMAS Peterson Lab collects eelgrass seeds from meadows in the South Shore Estuary Reserve.}