The Importance Of SAV In The Chesapeake Bay

Introduction Submerged aquatic vegetation (SAV) are plants that have adapted to live within aquatic environments (DNR 2011). SAV are able to float in the water and move with the currents because they contain specialized cells called aerenchyma that provide buoyancy and they lack the more rigid structures of most terrestrial plants (DNR 2011). Many different species of SAV are found throughout estuarine waters worldwide and there are seventeen species of SAV that are commonly found throughout the Chesapeake Bay and its tributaries (VIMS 2010). SAV is found throughout the Chesapeake Bay.

Importance of SAV SAV is very important in helping maintain the health of the Chesapeake Bay’s ecosystem since it provides food for many species
of finfish, shellfish, and other invertebrates in the Bay (DNR 2011). SAV beds provide protection from predators, while providing a rich foraging habitat for organisms such as fish. By foraging in SAV, fish are able to consume more prey because SAV supports vast quantities of small fish and other invertebrates (Rozas and Odum 1988). This may lead to higher fecundity and growth rates along with lower mortality rates for the fish, although this has yet to be thoroughly studied (Rozas and Odum 1988). SAV also releases oxygen during photosynthesis, which is utilized by underwater organisms such as fish and crabs (DNR 2011). Bay grasses inhibit wave action that causes eroding of shorelines and they also filter and trap sediments from the water column that would otherwise bury small organisms and cloud the water column (DNR 2011).
SAV is also a great barometer of water quality in the Bay (VIMS 2010). SAV beds filter polluted runoff and uptake nitrogen and phosphorus that can lead to harmful algal blooms that impair water quality (VIMS 2010). Based on my experience while performing SAV surveys, it was apparent that areas with cloudy water, shoreline erosion and higher pollution also had a lower abundance of SAV. Others have noted the relationship between pollution and SAV abundance (CBF 2011). The Chesapeake Bay Foundation recently reported that SAV appear to be thriving in locations in which pollution has been reduced, the upper Potomac River and Susquehanna Flats (CBF 2011). So, in cleaner areas, SAV abundance should be higher. SAV diversity may also contribute to improving water quality, although the topic has not been studied extensively. Diversity is important because different plants do things differently in terms of their ability to help trap sediments, slow down currents, provide different levels of oxygen and their ability to withstand different water temperatures and salinity levels. If one plant is too thin and light to trap suspended sediments, a thicker plant can trap the sediments to allow the maximum amount of light penetration in the water. So, the cleaner the area is, the more likely it is that SAV will be able to thrive.

Threats to SAV
There are many different threats to aquatic grasses in the Bay. Poor water quality is directly linked to the depletion of SAV populations (USGS 2008). One of the major threats affecting growth of SAV is poor water clarity, due to a combination of increased suspended sediment and persistent algal blooms (USGS 2008). The United States Geological Survey Science (USGS) analyzed factors influencing water clarity and found that the most important factor affecting water clarity is total suspended solids, which includes both organic matter and inorganic solids (USGS 2008). This impacts SAV abundance because the organic and inorganic solids decrease the amount of light reaching the SAV, leading to inefficient photosynthesis (USGS 2003). The suspended solids decrease water clarity, allowing less light to reach SAV. Thus water clarity is essential to SAV growth because more sunlight leads to a greater generation of energy by photosynthesis (USGS 2003).
SAV may also be threatened by human activities, such as dredging, marine construction, and boating (Erftemeijer and Lewis 2006). The potential effects of dredging on the marine environment include effects of the dredging process itself (removal of substratum from the seafloor) as well as effects caused by the process of disposal of dredge material (Erftemeijer and Lewis 2006). These affect water clarity because sediments may come into suspension from dredging, but also overflow from dredge barges, or leakage from hydrological dredging pipelines, during transport from the dredge and disposal site, can also impact SAV (Erftemeijer and Lewis 2006). The effects on water clarity from marine construction and boating are similar to the effects of dredging. Marine construction and boating impact water clarity by resuspension and disturbance of bottom sediments (Erftemeijer and Lewis 2006). Boat propeller turbulence in shallow waters can produce a significant increase in light attenuation (i.e., reduce light penetration) by increasing suspended sediments (Erftemeijer and Lewis 2006). Boats with a hull that skims across the water, known as a planing hull, produce the maximum increase in the resuspension of bottom sediments when operating at high speeds (Klein 2007). While some types of boats cause a disturbance to SAV, not all boats are harmful to SAV. Those who need to work in shallow waters know that a boat type to fit the water depth to minimize disturbance of SAV. Boats with small engines such as pontoons can be used in shallow waters because they draft less than two feet. This should allow someone to work in depths as shallow as approximately 2.5 feet. If the depths become shallower than 2.5 feet, kayaks can be used to complete the survey in that area so that SAV is not impacted.
Biological interactions can also present threats to SAV (CBF 2011). One such species is the mute swan, which eats significant amounts of SAV and can even deplete entire beds in some areas (CBF 2011). Water chestnut, an invasive aquatic plant, floats upon the water 's surface and blocks sunlight from reaching the submerged grasses, leading to depletion of SAV (CBF 2011). Dense algal blooms brought about by excess nutrients also affect SAV because they reduce sunlight and dissolved oxygen (U.S. FWS). The algae may also grow directly upon the leaves of the SAV, further reducing sunlight and leading to SAV depletion (U.S. FWS). Algae reduce oxygen levels during the decay process; after the bloom, the algae sinks to the bottom, decays, and the decomposing bacteria deplete dissolved oxygen from the water.
In order to minimize these negative impacts on SAV, policies and regulations have been implemented to protect them. SAV protection involves state and federal agencies, as well as private firms and volunteer groups working together to protect SAV.

Policies and Regulations that Help Protect SAV Policies and regulations have been implemented to help protect SAV habitats from human-based activities that are a major threat to SAV. SAV has had increased protection since the enactment of Section 404 of the Clean Water Act (CWA) and Section 10 of the Rivers and Harbors Act (CBP 1995). Permit applications to perform services such as dredging and marine construction are reviewed by the Army Corps of Engineers (COE), U.S. Environmental Protection Agency (EPA), U.S. Fish and Wildlife Service (USFWS), and the National Oceanic Atmospheric Administration (NOAA) in additional to local jurisdictions (CBP 1995). Each of these agencies has their own standards when it comes to permitting dredging or marine construction. For instance, the state of Maryland restricts new dredging of channels where water depths are less than 3 feet, whereas the EPA rules say no new dredging unless it occurs in a historic channel (CBP 1995). SAV usually inhabits shallow waters, so dredging in shallow waters is prohibited for this reason (CBP 1995). Maryland is in charge during dredging and filling activities and construction activities in tidal wetlands and shallow water areas in the state of Maryland, while the EPA reviews permits under the Clean Water and Rivers and Harbors Acts (CBP 1995). EPA and the state of Maryland also set timing restrictions as to when dredging can occur; most dredging is prohibited between the end of March and the end of June (CBP 1995). This restricts disturbance of SAV during its growing season. The COE policy for new marina development avoids historical SAV beds and maintains a buffer for marina expansion between the proposed location and known SAV beds (CBP 1995). There are many other policies and regulations that go along with obligations associated with permits for dredging and marine construction services. These policies reflect the importance of SAV to the Bay. New policies or agreements are implemented to protect SAV when previous policies are not working or enhancement of previous policies is needed to meet specified goals. Policies also change in response to data because our understanding of benefits from SAV and risks to SAV changes with data.
The 2000 Chesapeake Bay agreements were developed to respond to the many issues facing the Bay’s ecosystem (DNR N.D.). One of the sections in the agreement was created for the protection, preservation, and restoration of vital habitats and natural areas, which are essential for the survival of the living resources of the Chesapeake (DNR N.D.). One of the habitats included in the agreement was SAV. For instance, because Bay grasses were experiencing significant losses, the Chesapeake 2000 Bay Agreement called for restoration of 114,000 acres of SAV (DNR N.D.). This goal was then changed three years later to increase extent of SAV restoration/protection to 185,000 acres of SAV to be protected and restored by 2010 (DNR N.D.). These new restoration goals reflected historic abundances, measured as density and acreage, from the 1930 's through 2002 (CBP 2000). The densities and acreages are tracked from the data that is collected and analyzed in the VIMS annual SAV reports.
In 2002 89,659 acres of SAV were mapped in the Bay; this extent represented 48% of the 2010 restoration goal (VIMS 2003). SAV abundance fluctuated between 2002 and 2006, and then increased the following three years with a total of 85,914 acres of SAV mapped in 2009 (VIMS 2010). The amount mapped in 2009 represented about 46% of the 2010 restoration goal; in 2010 there were fewer total acres of SAV than what was found in 2002. Although SAV abundance in 2009 was still far away from the set goal, there is still some optimism for SAV because increases in SAV abundance occurred for three straight years.
The data collected from state, local, and federal agencies, volunteer groups, and private firms all help in determining how close we are in reaching restoration goals. For example, the SAV surveys that I helped complete during my internship in 2009 with Bayland Consultants were mapped out and the data was compiled and analyzed and submitted to VIMS for incorporation into their annual SAV report. These data were included in the overall abundance found in 2009, which helped determine how close we were in reaching the SAV restoration goal. Although there are several private companies that help complete ground SAV surveys throughout the Chesapeake, none are specifically acknowledged in the annual reports provided by VIMS (VIMS 2010). The ground surveys are used in conjunction with the aerial photography provided by government agencies (VIMS 2010). State and federal agencies and local governments such as Baltimore County, DNR, and EPA determine which areas are to be surveyed; these agencies also help complete ground surveys (VIMS 2010). The private sector is financed by federal and state agencies (VIMS 2010). The monitoring of SAV can help determine whether a policy is working, which is why it is important that federal and state agencies work together with the private sector to assure that each area is thoroughly surveyed.

Economic Costs of Protecting and Restoring SAV SAV restoration is required to meet the 2010 goals and restoration is expensive. Although restoration methods have improved over the years, SAV planting remains an extremely labor intensive and costly endeavor (COE 2005). In order to meet targeted SAV restoration goals, significant investments in research is needed to improve the knowledge surrounding restoration strategies, especially cost-effective means for large-scale restoration (COE 2005). A COE report on large scale restoration in the Bay estimated that hand planting adult eelgrass plants in the Potomac River would approximately cost $25,592 per acre (COE 2008). The revised Bay agreement from April 15, 2003 called for 1,000 acres to be planted throughout the Bay, which is trivial in light of the overall 185,000 acre goal that was to be reached by 2010 (COE 2005). Even if only 50 acres were to be planted in the Potomac, the cost would be $1,279,600. Only planting the 1,000 acres would cost tens of millions of dollars but this effort only accounts for this one-specific restoration project. Including the many other SAV restoration/protection projects/plans such as ones specifically for improving water clarity, protecting existing SAV beds, and enhancing education about SAV, the economic costs would be astronomical. The Bay is a regional resource and national treasure, therefore its restoration is important, but the high costs require a different/creative way in getting the job done.

The Role of Private Industry in Protecting/Restoring SAV Private companies have been engaged in supporting government agencies to ameliorate the stresses put on SAV.
Companies such as Bayland, assist the government in protecting SAV by performing jobs such as monitoring grass transplants and conducting SAV surveys. Depending on the project, the private company may either be hired by the state or government agency that overseas the project, or the private company may be a third party hired by the contractor that is working on the project. For instance, a grass transplanting project monitored by Bayland occurred at the Isle of Wight in Worchester County in 2002 (Shafer 2008). A shoreline protection project occurred at the Isle of Wight in 2003, but before the construction and dredging could start, SAV had to be removed where the proposed construction was going to occur (Shafer 2008). This provided an opportunity to use a new grass transplanting system so that the SAV that would have likely been damaged during dredging and construction could be relocated to a new area where SAV was absent (Shafer 2008). During this job Bayland helped design an independent monitoring program to monitor success of SAV that was transplanted to a new area at the Isle of Wight. This project could be considered a small scale SAV restoration project. Bayland completed a Monitoring Report in January 2005 and was contracted to continue to monitor the site through 2008 (Bayland Consultants & Designers, Inc. 2005). The transplanting system used for
this restoration project was designed by Seagrass Recovery Inc. and was new in the United States at this time (Shafer 2008). The system involved the removal, transport, and subsequent replanting of large planting units of intact SAV, complete with roots, rhizomes, and associated sediments (Shafer 2008). This method differs from planting individual planting units by hand. Planting individual units manually may be successful at times, but it is extremely labor intensive and costly and involves even smaller scale transplanting of around tens or hundreds of square meters (Shafer 2008). Smaller scale projects similar to the one at the Isle of Wight had been deemed successful in Australia. The study in Australia demonstrated that the planting success of large sods of seagrass was greater than that of individual planting units especially in high wave-energy environments (Shafer 2008).
The results at the Isle of Wight indicated that the survival rate for the Zostera was high, around 93% post-planting (Shafer 2008). Natural recolonization processes occurred during monitoring and demonstrated the creation of numerous small patches of eel-grass throughout the area, which suggested that site conditions were favorable for continued growth and expansion of the transplanted SAV (Bayland Consultants & Designers, Inc. 2005). The natural recruitment expanded outside the boundaries where the original planting units were transplanted. In the transplanting system, adult plants are used instead of seedlings which are usually used for large scale projects; this avoided high mortality seen in most restoration projects when seedlings fail to develop into adult plants (VIMS N.D.). Recent evidence suggests that physical factors such as waves and currents remove many young seedlings before they can develop (VIMS N.D.). The success using the strategy implemented at the Isle of Wight could be used for other related projects. This suggests that more projects similar to the one at the Isle of Wight should be proposed to enhance small scale restoration.
Private industry performs SAV surveys to assist government agencies in restoration/protection of SAV. Bayland performs about 50 SAV surveys annually throughout the upper and central Chesapeake Bay. The purpose of the SAV surveys are to document locations of existing beds to ensure proposed waterway improvement projects like, dredging, offshore breakwaters, living shorelines, and the construction of bulkheads and piers avoid SAV habitats or at least minimizes impacts to SAV. The data collected by Bayland during their SAV surveys include parameters such as species names, the density of the grass in a particular bed, water depth, and the number of different species located in that same bed. As described earlier, this data is entered into their geographic information system (GIS), which is submitted to the county and is then eventually sent to VIMS to be incorporated into their annual SAV reports. The annual SAV reports from VIMS were developed in 1984 to monitor the distribution and abundance of SAV. This data can be used to regulate and monitor the success of implemented restoration projects, which help aide the success of reaching SAV restoration goals (Wilcox et al. 2009). The data from the reports can then be used by government agencies to analyze and compare with historical data, which will allow them to develop methods and criteria for new SAV restoration acreage goals for the entire Bay and each of its tidal tributaries (Moore et al. 2004).
SAV surveys may be used for other purposes as well. One such purpose is to carefully assess the relationship between dredging and SAV. Dredging causes direct and indirect impacts to SAV. The physical removal of SAV during dredging is direct, whereas the reduction in light penetration and burial that is a result of the turbidity plumes and sedimentation created by the dredge are indirect impacts (NOAA 2008). The surveys become very important during the permitting process for dredging projects. Permitting is regulated by state and federal agencies (NOAA 2008). Data collected from historical pre- and post-dredge SAV surveys provide information about the physical impacts of dredging on SAV (NOAA 2008).
The well documented impact of dredging on SAV has led to SAV being placed in the special considerations section during the permit review process (NOAA 2008). The conservation recommendations and best management practices (BMPs) for dredging include avoiding dredging in areas with SAV, areas which historically supported SAV, and areas which have potential for recolonization by SAV (NOAA 2008). The BMPs for SAV protection also include reviewing historic surveys of the area and pre-dredge surveys because of the spatial and temporal dynamics of SAV (NOAA 2008). Having the current SAV data prior to the start of the dredging project helps the agencies determine where the actual dredging will occur and which areas need to be protected and monitored. The areas where SAV is found, areas that could be directly or indirectly impacted, are the likely places where post-dredge monitoring would occur. Post-dredge survey data is analyzed to assess the impacts on SAV from the dredging process. Bayland has performed many pre- and post-dredge surveys providing data to government agencies so that they can develop conservation recommendations for dredging projects. The recommendations will ultimately be placed in the special considerations section of the permit for the dredging project.
The Main Creek dredging project in Pasadena, MD required a permit application for the dredging project. The applicant for the permit was the Anne Arundel County Department of Public Works (AACDPW) (COE-B.D. 2008). Prior to the permit issue the AACDPW had to obtain a water quality certification in accordance with Section 401 of the Clean Water Act from the MDE, as well as certify that the proposed work would be in compliance with the Maryland Coastal Zone Program (COE-B.D. 2008). The purpose of the dredging was to improve navigable access to residential piers (COE-B.D. 2008). The permit was issued based on the evaluation of the probable cumulative impacts of the proposed dredging (COE-B.D. 2008). Prior to the dredging, three years of pre-dredge SAV surveys were conducted by Bayland and used to decide which areas should not be dredged to minimize impacts on SAV (Maryland BPW-W.A. 2008). As described earlier, the post-dredge survey information obtained by Bayland would be analyzed to determine the impacts on SAV from the dredging. The post-dredge surveys were also used to determine whether the special conditions for SAV were met, as described in the permit. The special conditions included no dredging between February 15 and October 15 to avoid impacts of SAV, three contiguous years of post-dredge SAV surveys to be compared to pre-dredge surveys to determine net gains or losses, and mitigations to offset SAV impacts based on any net loss calculated during the post assessment (Maryland BPW-W.A. 2008). If the net loss of SAV exceeded the maximum allowance, then a mitigation fee would have been assessed to the licensee. Therefore, private businesses can assist the state by performing the monitoring with the costs borne by the applicant. Overall, the role of private industry is important in assisting government agencies with the protection/restoration of SAV.

How is SAV Doing? There are numerous restoration projects and goals, along with all of the policies/regulations that go along with protecting SAV. Overall, the efforts of government agencies, private industry, and volunteer groups have helped improve the state of SAV; Table 1, below, presented the data from the last few years. The table shows the coverage in hectares in various sections of waterways in the Chesapeake Bay between 2007 and 2009.

Table 1: Change in SAV coverage over time. The numbers refer to the total area in hectares found in that segment during that year (Virginia Institute of Marine Science 2010).

LOCATION 2007 2008 2009
CB2OH - Upper Chesapeake Bay
150.80
256.13
301.67
SASOH1 - Sassafras River Segment 1
149.10
223.46
326.97
SASOH2 - Sassafras River Segment 2
1.64
21.36
21.52
BSHOH - Bush River
260.20
210.08
154.30
GUNOH1 - Gunpowder River Segment 1
226.19
316.76
345.81
GUNOH2 - Gunpowder River Segment 2
366.51
379.00
418.09
MIDOH - Middle River
222.73
334.54
315.79
BACOH - Back River
0.00
0.00
0.00
CB3MH - Upper Central Chesapeake Bay
49.98
76.38
94.88
PATMH - Patapsco River
3.67
7.34
4.67
MAGMH - Magothy River
33.56
36.28
4.90
CHSMH - Lower Chester River
27.34
33.50
38.58

As seen in Table 1, all of the segments, except for the Bush River segment, showed increases in SAV coverage between 2007 and 2008. Between 2008 and 2009, 7 of the 11 segments showed an increase. While it varied from site to site, the total SAV coverage area throughout the Chesapeake Bay increased by 12% from 31,104 hectares in 2008 to 34,768 hectares in 2009 (VIMS 2010). This marked the third year in a row that SAV abundance has increased; although a 12% increase may not sound like much, this was actually the second highest increase recorded in Maryland waters since the VIMS began their annual SAV reports in 1984 (DNR-O.C. 2010). This recent increase in SAV abundance has also helped increase the abundance of other species that inhabit the Bay. A 2011 news report indicated that the Chesapeake Bay’s blue crab population has increased substantially for the second straight year (DNR- O.C. 2010). The results of the most recent winter dredge surveys show a 60% increase in Maryland’s crab population, indicating that 2008 management measures are continuing to pay dividends with the crab population at its highest level since 1997 (DNR-O.C. 2010).

Assessment of Protection/Restoration There are many variables that go into the protection/restoration of SAV. This is why it is difficult to determine whether SAV is being sufficiently protected and restored at this time. Knowing that SAV plays a major role in helping the Chesapeake Bay’s ecosystem to remain diverse and healthy makes me believe that even with all of the current policies/regulations implemented to protect/restore SAV, more resources and funds need to be used to develop new and improved policies/regulations to further protect/restore SAV in the future. We may not need to change all the ways we restore/monitor SAV, but we certainly need to learn how to better prevent damage in the future. The reality of protecting and restoring SAV is that the more we try to restore/protect them, the more it will cost and it could also put an economic burden on the citizens living near the Bay.
Since the economy is suffering, an increase in restoration efforts would be too costly at this point in time. I suggest that we learn how to better minimize destruction of SAV through cost-effective methods such as providing more knowledge and awareness to citizens about SAV. Community marinas should also be developed in non-critical areas instead of more homeowners having access from their backyards to launch their boats. We need to learn from our past mistakes, and stop continuing to damage SAV populations. We also need to minimize damage from dredging and construction activities. I suggest that harsher penalties or higher fines should be assessed to the company or agency responsible for a project that damages too much SAV. I believe we are heading in the right direction to protect/restore SAV, but additional cost-effective and sufficient policies/regulations should be implemented in the near future so that the Bay can reap the benefits from a higher abundance of healthy SAV populations.

Conclusion
Aquatic grasses are known to be vital to the overall aquatic grasses are vital to the overall health of the Chesapeake Bay, and many policies and regulations have been implemented to help protect SAV. Protection and restoration of these grasses, ameliorating the multitude of stresses experienced by SAV, is now a joint venture of government and private industry. The increases in SAV abundance can be directly attributed to the work that government agencies, private firms, and volunteer groups have done in relation to SAV restoration/protection. Bay grasses will continue to have threats for many years to come. It is also almost impossible to salvage every SAV in the Chesapeake, but I believe that the restoration/protection of SAV is going in the right direction and can be considered successful at this time.

References

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