Coupling Oyster and SAV Restoration in South River, Maryland

Final Report to the National Oceanic and Atmospheric Administration Chesapeake Bay Office

Award Number NA05NMF4571249

Submitted by Rebecca Raves Golden

Maryland Department of Natural Resources Tidewater Ecosystem Assessment

580 Taylor Avenue, D-2 Annapolis, MD 21401

2

Introduction Oysters (Crassostrea virginica) and their reefs provide many benefits to estuarine

ecosystems, including filtering algae from the water column, improving water clarity,

protecting shorelines from erosion and providing habitat to a variety of aquatic

invertebrates and fishes (Newell, 2004). In the past 100 years, oyster populations in the

Chesapeake Bay have witnessed serious declines due to disease, harvest pressure and

degradation in habitat and water quality (Mackenzie, 1996). Based on estimates of

historic oyster populations and the filtering capacity of oysters, it is believed that 120

years ago, oysters could filter the entire volume of the Chesapeake Bay in three to six

days. Now, the remaining population would require a year to accomplish the same thing

(Newell, 1988).

Like oysters, submerged aquatic vegetation (SAV) populations within the Bay

and its tributaries are dramatically lower than they have been historically (Orth and

Moore, 1984). Based on a study of 1952 aerial photography, 73,000 acres of SAV were

identified in Maryland’s portion of the Chesapeake Bay (Naylor, 2002). A recent survey

performed by the Virginia Institute of Marine Science (Orth et al., 2008) found

approximately 35,000 acres of SAV in Maryland’s Chesapeake Bay in 2007, a decline of

52% since 1952.

Oysters and SAV are widely recognized as aquatic habitats vital to the health of

Chesapeake Bay, and their restoration has long been an important goal of the U.S. EPA’s

Chesapeake Bay Program and its partners. The Chesapeake 2000 Agreement calls for

increasing native oyster populations ten fold, comparable to harvest levels during the

period of 1920-1970. Additionally, the Strategy for the Protection and Restoration of

Submerged Aquatic Vegetation identifies a variety of actions necessary to increase SAV

3

populations in the Bay, including improving water clarity sufficient for supporting

healthy SAV populations and planting or reseeding 1,000 acres in strategic locations by

December, 2008.

It is hypothesized that if the Chesapeake Bay Oyster Restoration Goals in the

Environmental Protection Agency Chesapeake 2000 Agreement were met by 2010, that

benthic filtration would have dramatic benefits to SAV and other living resources. The

increased filtering capacity of the oysters could remove suspended material (algae and

sediments) from the water column, which would increase light penetration to the bottom,

a critical requirement for SAV survival and resurgence.

The concept of multiple habitat restoration has gained increased attention, and

several models have explored the hypothesis that oyster filtration can improve habitat

sufficiently to allow for the re-establishment of adjacent SAV communities. These

models suggest that modest increases in oyster biomass within the Chesapeake Bay can

lead to reduced suspended sediment concentrations by nearly an order of magnitude

(Newell and Koch, 2004), decreases in summer light attenuation by up to 13% (Cerco

and Noel, 2005b) and summer chlorophyll reductions up to 2.3 μg/L (Cerco and Noel,

2005b). Cerco and Noel (2005a) suggest that the water clarity improvements that

accompany oyster restoration produce increases in computed system-wide SAV biomass

of 25% to more than 60%. While the results of these models are promising, the

hypothesis that oyster filtration can improve water clarity sufficiently for SAV restoration

and resurgence in the Chesapeake Bay has not been tested in previous field studies.

We designed our project to test the efficacy of oyster filtration in improving water

clarity relative to the habitat requirements of submerged aquatic vegetation (Batiuk et al.,

4

1992, 2000; Dennison et al., 1993; Kemp et al., 2004). Specifically, the project

objectives include supplementing an existing oyster community to increase local oyster

filtration, monitoring temporal and spatial water quality to assess the influence of oyster

filtration on water quality, and planting SAV upstream of the oyster bar. This project

will investigate the practicality of multiple habitat restoration (SAV and oysters) and

attempt to quantify the impact of oyster filtration on local water clarity. This work will

support the Chesapeake 2000 Agreement to increase oyster populations and works

toward the Chesapeake Bay Program’s SAV Strategy’s goals of improving water clarity

and planting 1,000 acres baywide by 2010.

Study Area The study area was a small cove with a restricted mouth on Harness Creek, a tidal

creek flowing into South River near Annapolis, Maryland, which contained a newly

created 800m2 oyster bar (38.93653N, 76.50723W)(Karrh, 2005) (Figure 1). The total

surface area of the site was approximately 1 hectare, with an average depth of 1 meter,

containing approximately 14.8 million liters of water (including a 0.5-meter tidal

amplitude).

Additionally, the study area was a potential candidate for a multiple species

restoration project as SAV was not present in the immediate area, and the cove was

entirely within the riparian zone of an Anne Arundel County park (Quiet Waters Park),

and therefore closed to shellfish harvest. Oysters were abundant in the South River and

the South River Federation, a community based conservation group, was very active in

Harness Creek and involved with oyster restoration projects.

5

Methodology Oysters Oyster and spat addition

240,000 spat on shell were added to the oyster bar on September 20, 2006. Using

state funds, the spat were purchased from the Chesapeake Bay Foundation’s Oyster

Restoration Center (ORC) and seeding was performed by the R/V Patricia Campbell.

The spat were added to increase the local effect of bivalve filtration on water quality.

The South River Federation placed 67 bushels on the oyster reef on July 18th,

2007. Another 32 bushels of oysters were placed on the bar on August 24th, 2007. The

~39,000 oysters were 1 or 2 years old and were grown through an oyster gardening

program. The shell length of these oysters ranged between 25 and 70 millimeters.

Oyster monitoring

In order to determine the effects of oyster filtration on local water quality, oyster

abundance, oyster mortality and oyster shell length were measured on June 13th, 2006,

August 30th, 2006, June 28th, 2007, September 28th, 2007 and October 21st, 2008.

Haphazardly selected 0.25 square meter plots (n = 12) were quantitatively sampled for

live oysters and recently dead (box) oysters in 2006. In 2007 and 2008, random plot

locations (n = 12) were generated in ArcView 9.3 (ESRI, Redlands, CA) to reduce

sampling bias. All material (live oysters and shell) in the plots to a depth of 10 cm was

manually removed by divers and placed in mesh bags. The mesh bags were loaded on to

an anchored support boat and the total number of oysters and boxes per plot were counted

immediately, and up to 15 individual live oysters (adult and juvenile) per plot were

measured to the nearest millimeter. The oysters and shell material were returned to the

oyster bar after observations were completed.

6

Parasite analysis

Live oysters (n = 30) were annually collected for parasite (Perkinsus marinus)

analysis. The oysters were placed in coolers with damp newspaper and ice packs and

transported to the laboratory within 24 hours of collection. Ray's Fluid Thioglycolate

Assay procedure (1952, 1954, 1966) was performed by Dr. Kennedy Paynter’s

laboratory, Department of Biology, University of Maryland in 2006, the Diagnostics and

Histology Laboratory at the Cooperative Oxford Laboratory in Oxford, MD in 2007 and

2008 and the Marine and Estuarine Ecology Laboratory at the Smithsonian

Environmental Research Center (SERC) in Edgewater, MD in 2008.

Water quality monitoring To assess the impact of oyster filtration on water quality, specifically water

clarity, a multi-part water quality monitoring plan was established. Water quality was

analyzed through several monitoring activities conducted under the Maryland

Department of Natural Resources’ Shallow Water Quality Monitoring Program.

Temporal monitoring

In order to account for temporal influences on water quality surrounding the

oyster bar, two YSI 6600 EDS units with LiCor sensors were installed on pilings

upstream (38.93648N, 76.5074W) and downstream (38.93598N, 76.5077W) of the oyster

bar on June 7th, 2006 (Figure 2). The monitoring stations were located approximately ten

meters from the oyster bar. Water depth, water temperature, specific conductance, pH,

dissolved oxygen, fluorescence and turbidity were measured in-situ every fifteen minutes.

7

Continuous monitoring deployments occurred from June through October 2006, April

through October, 2007 and March through November, 2008. Quality assurance/control

procedures were performed in accordance with the Maryland Department of Natural

Resources Shallow Water Monitoring Program (Michael et al., 2006, 2007 and 2008).

Discrete monitoring

Discrete sampling stations were located at each of the temporal monitoring

stations. Bi-weekly grab samples were taken and filtered on-site or immediately after

returning to the laboratory and Secchi depth was also measured. The processed samples

were sent to the Nutrient Analytical Services Laboratory (NASL) at the Chesapeake

Biological Laboratory and to the Maryland Department of Health and Mental Hygiene

(DHMH) for analysis. The following parameters were analyzed at NASL: dissolved

inorganic nitrogen, orthophosphate and total suspended solids. Chlorophyll a samples

were analyzed at DHMH.

Spatial monitoring

Water quality mapping was conducted from April through October in 2006 in the

South River (including Harness Creek) using a shipboard system of geospatial equipment

and water quality probes that measured water quality parameters from a flow-through

stream of water collected near the water’s surface. The water quality parameters

measured included water depth, water temperature, specific conductance, pH, dissolved

oxygen, fluorescence and turbidity. The water was pumped through a ram (pipe),

through the YSI 6600 sensors, and then discharged overboard. Each water quality datum

8

was associated with a date, time, water depth, and georeferenced. Quality

assurance/control procedures were performed in accordance with the Maryland

Department of Natural Resources Shallow Water Monitoring Program (Michael et al.,

2006, 2007 and 2008).

The three-year spatial water quality assessment of the South River was completed

in 2006. In order to continue our collection of spatial water quality data in Harness

Creek, water quality profiles were initiated in April 2007. Water quality was monitored

at four vertical profile stations (Table 1), located directly over the oyster bar, and spaced

approximately 10 meters apart, in order to assess spatial changes in water quality due to

increased oyster filtration. In an effort to increase efficiency during site visits, the

number of vertical profile stations was decreased to three in 2008 (Table 2). Hydrolab

probes collected in-situ turbidity and chlorophyll a every 0.5 meters in depth at each

station. PAR (photosynthetically active radiation) data was also collected at 0.5 meter

depth intervals at each station.

SAV culture and transplant Redhead (Potamogeton perfoliatus) and sago pondweed (Stuckenia pectinata)

were cultured in March, 2006 at the Maryland Department of Natural Resources’ Fort

Meade Laboratory. Additional redhead and sago pondweed were grown by John

Sandkuhler, a teacher at the Forbush School in Baltimore, Maryland. The Bay Grasses in

Classes methodology was used to grow the material from cuttings

(http://www.dnr.maryland.gov/bay/sav/bgic/download/System%20Set-

up%20and%20Maintenance.pdf). The redhead and sago pondweed were transported to

the study area and planted inshore of the oyster bar in 0.5-1 meter of water on July 20,

9

2006. The plants were transplanted in methods adapted from Fonseca et al. (1998) and

Orth et al. (1999). The total planting area was approximately 100 m2 and was subdivided

using a two-factor modified split-plot design (Underwood, 1997) with species (redhead or

sago pondweed) and planting type (bare root or plug method) as independent variables.

Each species/planting type treatment had two replicates for a total of eight plots, with an

area of approximately 12.5 m2. Bamboo garden stakes placed in each corner of the plots

identified the transplant area.

Data Analysis Data were entered and stored using standard Maryland Department of Natural

Resources protocols. Oyster monitoring data was analyzed using a 1-Way analysis of

variance (ANOVA) or a non-parametric 1-Way ANOVA (Kruskal-Wallis) if

transformation was not possible to assess differences in sampling date. Differences in

temporal water quality data were analyzed using a Wilcoxon Signed Rank test to assess

differences in station and tidal stage. Bi-weekly discrete water quality data was analyzed

using a 2-Way ANOVA to assess differences between stations and among sampling

dates. Monthly spatial mapping data was interpolated using the inverse distance

weighted method in the Spatial Analyst extension of ArcView 9.3 (ESRI, Redlands, CA).

Bi-weekly water quality profile data was analyzed using a 3-Way ANOVA to assess

differences in station, depth (nested in station) and among sampling date. If significant

differences were detected, multiple comparisons were made using the Student-Newman-

Keuls test.

10

Results Oysters Oyster monitoring

Mean total (adult and juvenile) oyster density (±SD) ranged from 64.2 (±64.5) to

189.3 (±137.2) oysters/m2 and was significantly (p = 0.0264) different among sampling

dates (Figure 3). Mean adult oyster density (63-149 oysters/m2) and juvenile density (10-

42 juveniles/m2) were not significantly different (p = 0.0794 and 0.1800, respectively)

among sampling dates. Average adult oyster size was significantly (p < 0.0001) different

over the monitoring period (Figure 3). Mean oyster shell length (±SD) ranged from 72.5

(±16.2) to 84.0 (±19.2) mm with a maximum mean length of 84.0 (±19.2) mm. Oyster

mortality increased from 20.6 to 33.9% and was not significantly (p 0.2819) different

among sampling periods (Figure 4).

Parasite analysis P. marinus prevalence and infection intensity increased over the sampling period

(Figure 4). In 2006, the test results indicated an 87% P. marinus (Dermo) prevalence, or

percent proportion of infected oysters in the sample. The test also indicated that the

oysters analyzed in 2006 had a mean infection intensity of 1.8, which is considered a

moderate risk of mortality (Dr. Kennedy Paynter, Research Associate Professor,

Department of Biology, University of Maryland, personal communication). The 2007

test results indicated a 100% prevalence of P. marinus and an infection intensity of 3.5

(0-7 scale, where 5 and greater are imminently lethal). The percentage of oysters with

lethal infection intensities (≥5) was 23%. 2008 results received from the Cooperative

Oxford Laboratory indicated that the oyster sample from the Harness Creek had an

infection prevalence of 100% and a mean infection intensity of 4.4 (0-7 scale). 53% of

11

the oysters sampled had lethal infection intensities (> 5). Results from SERC also

indicated that 100% of the oysters sampled were infected with Dermo, with a mean

infection intensity of 2.5 (0-6 scale). 22% of the oysters sampled had lethal infection

intensities (> 4).

Water quality monitoring Temporal monitoring

All measured parameters, except chlorophyll concentrations, were significantly

different (p < 0.0001) between the upstream and downstream monitoring stations for all

monitoring years (2006-2008) (Table 3) when analyzed across all tidal stages. While all

parameters were analyzed, only the results of the chlorophyll and turbidity are presented

as they are the most relevant to the project. Chlorophyll levels were significantly higher

(0.9 μg/L) (p < 0.0001) at the downstream station in 2007, but there were no observed

differences in concentrations between stations in 2006 or 2008 (Table 3). Mean turbidity

levels were higher upstream of the oyster bar in 2006 (2.3 NTU) and 2007 (4.4 NTU),

and concentrations were 0.7 NTU less upstream in 2008 (Table 3).

Chlorophyll and turbidity levels also differed when analyzed by tidal stage (Table

3). Mean turbidity was significantly higher at the upstream station on flood and ebb tides

in 2006 and 2007, but significantly lower upstream for all tidal stages in 2008. No

statistical differences in turbidity levels were observed during slack tide in 2006 and

2008, but significant differences in turbidity were seen in 2007. Differences in

chlorophyll concentrations between the two monitoring stations varied depending on year

(Table 3). Mean concentrations were significantly greater upstream of the oyster bar on

ebb tides in 2007 and flood tides in 2008. Chlorophyll levels were significantly lower

12

upstream during ebb tides in 2006 and during flood tides in 2007. There were no

significant differences in chlorophyll concentrations during slack tide in all years of the

project.

Temporal data (2006-2008) for the downstream (ZDM0001) and upstream

(ZDM0002) stations can be accessed at

http://mddnr.chesapeakebay.net/newmontech/contmon/archived_results.cfm

Discrete monitoring The results indicted that no detectable differences (p > 0.0711) in light

attenuation, Secchi depth, orthophosphate, dissolved inorganic nitrogen and total

suspended solids were observed between sampling station or year. Annual summary

plots for bi-weekly discrete monitoring parameters are included in Appendix 2.

Spatial monitoring Two of the seven monthly spatial mapping cruises on the South River in 2006

collected water quality data over the oyster bar, therefore interpolations could only be

performed on data from July and August, 2006. The interpolations suggest that turbidity

was 2-3 NTU lower in localized areas surrounding the oyster bar. There appeared to be

no observed difference in chlorophyll values near the oyster bar in July, 2006; however,

the interpolation of August 2006 data suggests that chlorophyll concentrations were 3-11

μg/L lower in some areas of overlying water. July and August, 2006 interpolations are

included in Appendix 3.

Bi-weekly profile data (light attenuation, turbidity and chlorophyll

concentrations) varied significantly with sampling date. Light attenuation was highest

13

during the summer monitoring periods for both years. Turbidity concentrations were

greater in the summer and early fall, while chlorophyll concentrations were generally

higher in the spring and early summer. Turbidity measurements also varied significantly

with station (p = 0.0114) and depth (p < 0.0001) for 2007 (higher concentrations were

observed inshore of the oyster bar and at deeper depths) and significantly (p = 0.0015)

increased with sampling depth in 2008. Chlorophyll concentrations were not

significantly different among stations or sampling depth in 2007 or 2008. Summary plots

for bi-weekly profile data are included in Appendix 4.

SAV culture and transplant Redhead grass and sago pondweed transplants were monitored on August, 30,

2006, approximately one month after transplant. No above-ground or exposed below-

ground biomass was observed in the planting area during initial monitoring or in

subsequent monitoring events.

Discussion Additional oysters and spat on shell were added to the existing oyster bar as

original density estimates and expected filtering capacity were not observed (Karrh,

2005). There are several possible explanations for the lower than expected oyster

densities observed during the monitoring period. First, our haphazard design may have

biased our sampling to the outer edge of the bar, missing more densely populated areas.

However, variability in oyster density was also observed when sampling protocols were

switched to a random sampling design in 2007. Secondly, two different environmental

organizations contacted us, expressing concerns that the oyster bar may have been

14

poached, based on documented occurrences at other oysters bars in South River.

However, mean oyster shell length increased over the monitoring period (with the

exception of the addition of smaller (20-70 mm) oysters in the late summer of 2006)

indicating that larger, market-sized (“poachable”) oysters remained on the bar.

The prevalence and infection intensity of Dermo disease (P. marinus) on the

oyster bar increased steadily throughout the monitoring period. While the increased

disease presence on the oyster bar is disappointing, prevalence and intensities were

comparable to other oyster bars in the South River (Tarnowski, 2007; Chris Dungan,

Oyster Disease Research Scientist, Oxford Cooperative Laboratory, Maryland

Department of Natural Resources, personal communication). Observed Dermo

prevalence was > 60% for oyster bars monitored during Maryland’s annual fall oyster

survey (Tarnowski, 2007) in 2005 and 2006. Oyster mortality on the Harness Creek bar

also increased from 20% to 34% during the monitoring period. Average mortalities for

monitored bars in the South River ranged from 11 to 25% in 2006 (Tarnowski, 2007).

Given the increases in disease prevalence and intensity, as well as observed mortality,

observed on the Harness Creek oyster bar, it seems that natural causes and sampling

variability, rather than poaching, are the likely causes of the lower than expected oyster

density observed during the sampling period.

Despite the lower than expected oyster abundance on the bar, the current oyster

population should have the ability to filter the 14.8 million liters of water in the study

area every 8 to 53 hours. This rough estimate assumes a mean particle clearance rate of

6.4 l h-1 g-1 (Newman and Koch, 2004;) a mean grams dry weight to oyster ratio ranging

from of 0.857 to 1.9 (Newell and Koch, 2004; Oyster Management Plan, 2005; Ross and

15

Luckenbach, 2006) and observed oyster densities ranging from 64 to 189 oysters/m2 with

mean shell lengths ranging from 72.5 to 84 millimeters during summer conditions.

The results of the water quality monitoring suggest that the oyster bar is having a

localized impact on water quality in Harness Creek. However, the observed

improvements were highly dependent on the type and frequency of monitoring utilized,

as well as seasonal and spatial variability in the parameters measured. Analysis of bi-

weekly discrete and in-situ monitoring revealed no significant differences in water clarity

(light attenuation and Secchi depth), dissolved inorganic nitrogen and phosphorus,

chlorophyll, turbidity and total suspended solids between upstream and downstream

sampling stations or after oysters were added to the bar. Localized reductions in

chlorophyll (0-11μg/L) and turbidity (2-3 NTU) concentrations were observed in close

proximity of the oyster bar when summer (July and August) 2006 spatial mapping data

was interpolated. Analysis of the temporal data suggests that the oyster bar is having the

desired impact on water quality. With the exception of 2007 turbidity measurements, no

significant differences in chlorophyll or turbidity concentrations were observed over the

oyster bar during slack tides. However, differences in chlorophyll (0.17-2.3 μg/L) and

turbidity (0.5-4.6 NTU) were observed during flood and ebb tides, suggesting that the

improvements in water quality are occurring as water flows across the oyster bar.

The project was successful in documenting measurable in-situ differences in

water quality upstream and downstream of the oyster bar. However, these differences in

water quality, specifically reductions in suspended solids, chlorophyll and summer light

attenuation, were not as drastic as predicted by the models (Newell and Koch, 2004;

Cerco and Noel, 2005a, 2005b). The results of this project suggest that light attenuation

16

and suspended solid concentrations were reduced by the addition of the oyster bar.

Reductions in chlorophyll concentrations up to 2.3 μg/L were observed in the vicinity of

the oyster bar. This improvement in chlorophyll concentrations is comparable to the 2.3

μg/L reduction in modeled chlorophyll levels when simulated oyster populations were

increased 50 fold (Cerco and Noel, 2005b).

While improvements in water quality, specifically chlorophyll concentrations and

turbidity levels, were observed, the ambient water clarity and suspended material

(sediments and chlorophyll) were not conducive to SAV growth or survival. Mean

Secchi depths (meters) exceeded SAV habitat criteria (0.96m) throughout the project, yet

measured light attenuation (KD) did not meet SAV habitat criteria (1.5) during the same

time frame. Dissolved inorganic nitrogen and phosphorus concentrations met SAV

habitat criteria, 0.15 mg/L and 0.01 mg/L, respectively, both upstream and downstream

of the oyster bar in all years of the project. Chlorophyll concentrations (15 μg/L) and

total suspended solids levels (15 mg/L) hovered at SAV habitat thresholds throughout the

project. The high suspended solid and chlorophyll concentrations and subsequent low

water clarity suggests that although improvements in water quality were observed, the

ambient concentrations of SAV habitat criteria played a role in the failure of the redhead

grass and sago pondweed transplants inshore of the oyster bar.

17

Recommendations for Future Work • Future projects involving similar multiple habitat restoration objectives should

include monitoring of the ecological function of the oyster bar (species diversity

of fish, epibenthic and benthic communities, etc.) in addition to water quality

improvements

• The impact of environmental factors, such as disease and natural mortality, should

be considered when the restored population or habitat density is a key factor in

achieving project goals

• Long-term trends and annual variation in measured water quality parameters

should be considered when observed improvements in water quality are project

objectives

• Monitoring frequency and scale is crucial to provide sufficient resolution to

explain observed changes in water quality due to oyster filtration

• The role of long-term trends and regional events or extremes in SAV habitat

criteria must be considered in restoration projects

• More field studies are needed in order to refine and validate environmental

models researching living resources and habitat improvement

References Batiuk, R.A., R.J. Orth, K.A. Moore, W.C. Dennison, J. C. Stevenson, L.W. Staver, V. Carter, N.B. Rybicki, R.E. Hickman, S. Kollar, S. Bierber and P. Heasly. 1992. Chesapeake Bay Submerged Aquatic Vegetation Habitat Requirements and Restoration Targets: a Technical Synthesis. U.S. EPA Chesapeake Bay Program. Annapolis, Maryland. 186 pp. Batiuk, R. A., P. Bergstrom, M. Kemp, E. Koch, L. Murray, J. C. Stevenson, R. Bartleson, V. Carter, N. Rybicki, J. Landwehr, C. Gallegos, L. Karrh, M. Naylor, D. Wilcox, K. Moore, S. Ailstock and M. Teichberg. 2000. Chesapeake Bay Submerged Aquatic Vegetation Water Quality and Habitat-Based Requirements and Restoration Targets: A Second Technical Synthesis. US EPA Chesapeake Bay Program. Annapolis, Maryland. 217 pp. Cerco, CF and MR Noel. 2005a. Assessing a Ten-Fold Increase in the Chesapeake Bay Native Oyster Population. A report to the EPA Chesapeake Bay Program. US Army Engineer Research and Development Center, Vicksburg, MS. Cerco, CF and MR Noel. 2005b. Evaluating Ecosystem Effects of Oyster Restoration in Chesapeake Bay. A report to the Maryland Department of Natural Resources. US Army Engineer Research and Development Center, Vicksburg, MS. Chesapeake Bay Program. 2005. 2004 Chesapeake Bay Oyster Management Plan. CBP/TRS227/06. Dennison, W.C., R.J. Orth, K.A. Moore, J. C. Stevenson, V. Carter, S. Kollar, P.W. Bergstrom and R.A. Batiuk. 1993. Assessing water quality with submerged aquatic vegetation. Bioscience 43(2): 86-93. Fonseca, M.S., W. J. Kenworthy and G.W. Thayer. 1998. Guidelines for the Conservation and Restoration of Seagrasses in the United States and Adjacent Waters. NOAA Coastal Ocean Program Decision Analysis Series No. 12. NOAA Coastal Ocean Office, Silver Spring, MD. pp. 222. Karrh, L. 2005. Coupling Oyster and Future SAV Restoration; A demonstration project. Report to the National Oceanic and Atmospheric Administration Community-based Restoration Program Award Number NA17FZ2768. Kemp, M., W. R. Batiuk, R. Bartleson, P. Bergstrom, V. Carter, C. L. Gallegos, W. Hunley, L. Karrh, E. W. Koch, J. M. Landwehr, K. A. Moore, L. Murray, M. Naylor, N. B. Rybicki, J. C. Stevenson, and D. J. Wilcox. 2004. Habitat requirements for submerged aquatic vegetation in Chesapeake Bay: Water quality, light regime, and physical-chemical factors. Estuaries 27(3):363–377.

19

Mackenzie, JR., C.L. 1996. Management of natural populations. In V. S. Kennedy, R. I. E. Newell, and A. Eble (eds.), The Eastern Oyster, Crassostrea virginica. Maryland Sea Grant Publication, College Park, Maryland. pp. 707–721 Michael, B., Trice, M. and C. Trumbauer. 2006. Quality Assurance Project Plan for the Maryland Department of Natural Resources Chesapeake Bay Shallow Water Quality Monitoring Program for the period July 1, 2006 - June 30, 2007. Prepared by Maryland Department of Natural Resources, Tidewater Ecosystem Assessment for U.S. Environmental Protection Agency Chesapeake Bay Program. Michael, B., Trice, M. and C. Trumbauer. 2007. Quality Assurance Project Plan for the Maryland Department of Natural Resources Chesapeake Bay Shallow Water Quality Monitoring Program for the period July 1, 2007 - June 30, 2008. Prepared by Maryland Department of Natural Resources, Tidewater Ecosystem Assessment for U.S. Environmental Protection Agency Chesapeake Bay Program. Michael, B., Trice, M., and C. Trumbauer. 2008. Quality Assurance Project Plan for the Maryland Department of Natural Resources Chesapeake Bay Shallow Water Quality Monitoring Program for the period July 1, 2008 - June 30, 2009. Prepared by Maryland Department of Natural Resources, Tidewater Ecosystem Assessment for U.S. Environmental Protection Agency Chesapeake Bay Program. Naylor, M. 2002. Historic Distribution of Submerged Aquatic Vegetation (SAV) in Chesapeake Bay, MD. Chesapeake Bay Program Technical Report. 17 pp. Newell, R.I.E. 1988. Ecological Changes in Chesapeake Bay: Are they the result of overharvesting the American oyster (Crassostrea virginica). In M. Lynch (ed.), Understanding the Estuary: Advances in Chesapeake Bay Research. Chesapeake Research Consortium Publication 129, Gloucester Point, Virginia. pp. 536–546. Newell, R.I.E. 2004. Ecosystem influences of natural and cultivated populations of suspension-feeding bivalve molluscs: A review. Journal Shellfish Research 23:51–61. Newell, R.I.E. and E.W. Koch. 2004. Modeling seagrass density and distribution in response to changes in turbidity stemming from bivalve filtration and seagrass sediment stabilization. Estuaries. 27(5): 793-806. Orth, R.J. and K.A. Moore. 1984. Distribution and abundance of submerged aquatic vegetation in Chesapeake Bay: An historical perspective. Estuaries 7:531–540. Orth, R.J., M.C. Harwell and J.R. Fishman. 1999. A rapid and simple method for transplanting eelgrass using single, unanchored shoot. Aquatic Botany 64: 77-85. Ray, S.M. 1952. A culture method for the diagnosis of infections with Dermocystidium marinum Mackin, Owen, and Collier in oysters. Science 116: 360-361.

20

Ray, S.M. 1954. Biological Studies of Dermocystidium marinum, a Fungus Parasite of Oysters. Rice Institute Pamphlet, Houston, TX, 114pp. Ray, S.M. 1966. A review of the culture method for detecting Dermocystidium marinum, with suggested modifications and precautions. Proceedings of the National Shellfisheries Association 54: 55-69. Ross, P.G. and M.W. Luckenbach. 2006. Relationships between shell height and dry tissue biomass for the eastern oyster (Crassostrea virginica). 9th International Conference on Shellfish Restoration. Charleston, S.C. November 2006. Tarnowski, M. 2007. Maryland Oyster Population Summary Status Report. 2006 Fall Survey. 40 pp. MDNR Publ. No. 17-7272007-233. Underwood, A.J. 1997. Experiments in Ecology: Their logical design and interpretation using analysis of variance. Cambridge University Press, Cambridge, UK. pp 385-415.

Figure 1. Location of Study Area, Hurricane Hole, Harness Creek, South River, MD. a) b)

Figure 2. Harness Creek Continuous Monitoring Stations. a) Downstream Station, b) Upstream Station.

22

Mean Oyster Density and Shell Length

0

20

40

60

80

100

120

140

160

180

200

06/13/06 08/30/06 06/28/07 09/28/07 10/21/08

Sampling Date

Den

sity

(#/m

2 )

66

68

70

72

74

76

78

80

82

84

86

Leng

th (m

m)

Adult Density Juvenile Density Shell Length

Figure 3. Mean oyster density and mean shell length observed during each sampling date. Lower case letters denote statistical differences (α < 0.05) in mean shell length. Upper case letters denote statistical differences (α < 0.05) in mean oyster density.

Mean Oyster Mortality and Dermo Prevalence

0

5

10

15

20

25

30

35

40

10/31/06 06/28/07 09/28/07 12/11/07 10/21/08

Sampling Date

Obs

erve

d M

orta

lity

(%)

60

65

70

75

80

85

90

95

100

Der

mo

Prev

alen

ce (%

)

% Mortality Prevalence

Figure 4. Mean oyster mortality and P. marinus (Dermo) prevalence observed in oysters samples collected from each sampling date. Letters denote statistical differences.

a

b b

c

A ABABB AB

23

Table 1. 2007 Water Quality Vertical Profile Stations. Station Latitude (NAD83) Longitude (NAD83) ZDM0001.2 38.93617 -76.50773 ZDM0001.4 38.93627 -76.50768 ZDM0001.6 38.93636 -76.50761 ZDM0001.8 38.93642 -76.50752

Table 2. 2008 Water Quality Vertical Profile Stations. Station Latitude (NAD83) Longitude (NAD83) ZDM0001.2 38.93617 -76.50773 ZDM0001.5 38.93637 -76.50768 ZDM0001.8 38.93642 -76.50764

Table 3. Summary statistics and results of Wilcoxon Signed Rank tests comparing differences in turbidity (NTU) and chlorophyll concentrations (μg/L) upstream and downstream of oyster bar. Negative mean values represent higher concentrations upstream and positive mean values represent higher values downstream. Significant differences (p < 0.05) are in bold.

2006 2007 2008

Mean N p value Mean N p value Mean N p valueTurbidityflood tide -2.57 2124 < 0.0001 -4.15 5251 < 0.0001 0.55 562 0.0003slack tide -1.63 69 0.0741 -5.17 182 < 0.0001 0.71 21 0.6150ebb tide -2.33 2026 < 0.0001 -4.57 5833 < 0.0001 0.9 684 < 0.0001all tidal stages -2.29 4456 < 0.0001 -4.38 11266 < 0.0001 0.74 1267 < 0.0001

Chlorophyllflood tide -1.04 2577 0.7495 2.30 4680 < 0.0001 -2.16 602 < 0.0001slack tide 0.02 80 0.8735 -4.77 164 0.8876 1.84 25 0.2497ebb tide 0.67 2331 < 0.0001 -0.17 5247 < 0.0001 0.42 718 0.1222all tidal stages -0.47 5223 0.3010 -0.90 10091 < 0.0001 -0.71 1345 0.1301

24

Appendix 1. Project events occurring during reporting period (01/01/2006-12/31/2008). Date Event 04/26/2006 Water quality mapping 05/30/2006 Water quality mapping 06/07/2006 Continuous water quality monitor deployment, discrete water quality

monitoring 06/13/2006 Oyster health and survival monitoring 06/21/2006 Discrete water quality monitoring 06/26/2006 Water quality mapping 07/03/2006 Discrete water quality monitoring 07/19/2006 Discrete water quality monitoring 07/20/2006 SAV transplants planted 07/27/2006 Water quality mapping 08/02/2006 Discrete water quality monitoring 08/16/2006 Discrete water quality monitoring 08/25/2006 Water quality mapping 08/30/2006 Discrete water quality monitoring, oyster health and survival

monitoring, SAV transplants monitored 09/13/2007 Discrete water quality monitoring 09/27/2006 Discrete water quality monitoring 09/29/2006 Water quality mapping 10/11/2006 Discrete water quality monitoring 10/24/2006 Discrete water quality monitoring, end of continuous monitor

deployment 10/26/2006 Water quality mapping 10/31/2006 Oyster collection for parasite analysis 04/11/2007 Continuous water quality monitor deployment 04/24/2007 Discrete water quality monitoring, water quality vertical profiles 05/08/2007 Discrete water quality monitoring, water quality vertical profiles 05/22/2007 Discrete water quality monitoring, water quality vertical profiles 06/19/2007 Discrete water quality monitoring, water quality vertical profiles 06/25/2007 Received parasite analysis results 06/28/2007 Oyster health and survival monitoring 07/03/2007 Discrete water quality monitoring, water quality vertical profiles 07/17/2007 Discrete water quality monitoring, water quality vertical profiles 07/18/2007 67 bushels of oysters added to reef by South River Federation 07/31/2007 Discrete water quality monitoring, water quality vertical profiles 08/14/2007 Discrete water quality monitoring, water quality vertical profiles 08/24/2007 32 bushels of oysters added to reef by South River Federation 08/28/2007 Discrete water quality monitoring, water quality vertical profiles 09/11/2007 Discrete water quality monitoring, water quality vertical profiles 09/25/2007 Discrete water quality monitoring, water quality vertical profiles 09/28/2007 Oyster health and survival monitoring 10/22/2007 Discrete water quality monitoring, water quality vertical profiles, end of

continuous monitor deployment

25

12/11/2007 Oyster collection for parasite analysis 12/20/2007 Received parasite analysis results 03/24/2008 Monitoring stations installed, discrete water quality monitoring, water

quality vertical profiles 04/03/2008 Discrete water quality monitoring 04/16/2008 Discrete water quality monitoring, water quality vertical profiles 04/30/2008 Discrete water quality monitoring, water quality vertical profiles 05/14/2008 Discrete water quality monitoring, water quality vertical profiles 05/27/2008 Discrete water quality monitoring, water quality vertical profiles 06/10/2008 Discrete water quality monitoring 06/24/2008 Discrete water quality monitoring, water quality vertical profiles 07/08/2008 Discrete water quality monitoring, water quality vertical profiles 07/25/2008 Discrete water quality monitoring 08/05/2008 Discrete water quality monitoring, water quality vertical profiles 08/19/2008 Discrete water quality monitoring 09/03/2008 Discrete water quality monitoring, water quality vertical profiles 10/01/2008 Discrete water quality monitoring, water quality vertical profiles 10/21/2008 Oyster health and survival monitoring, oyster collection for parasite

analysis 10/29/2008 Received parasite analysis results 10/31/2008 Received parasite analysis results 11/13/2008 Discrete water quality monitoring, end of continuous monitor

deployment

26

Appendix 2a. Annual summary plots for biweekly discrete monitoring data for downstream station.

27

Appendix 2b. Annual summary plots for biweekly discrete monitoring data for upstream station.

28

Appendix 3. Spatial water quality mapping interpolations for Harness Creek, South River, MD for July and August 2006. July, 2006 Chlorophyll August, 2006 Chlorophyll

July, 2006 Turbidity August, 2006 Turbidity

29

Appendix 4a. 2007 and 2008 bi-weekly profile sampling chlorophyll (μg/L) data. 04/2007 5/2007a

05/2007b 06/2007

07/2007a 07/2007b

30

07/2007c 08/2007a

08/2007b 09/2007a

09/2007b

31

03/2008 04/2008a

04/2008b 05/2008a

05/2008b 06/2008

32

07/2008 08/2008

09/2008 10/2008

33

Appendix 4b. 2007 and 2008 bi-weekly profile sampling turbidity (NTU) data. 04/2007 05/2007a

05/2007b 06/2007

07/2007a 07/2007b

34

07/2007c 08/2007a

08/2007b 09/2007a

09/2007b

35

03/2008 04/2008a

04/2008b 05/2008a

05/2008b 06/2008

36

07/2008 08/2008

09/2008 10/2008