Effects of Sea Level Rise on the Intertidal Oyster ...

Effects of Sea Level Rise on the Intertidal Oyster Crassostrea Virginica by Field Experiments Author(s): Joshua A. Solomon, Melinda J. Donnelly, and Linda J. Walterst Source: Journal of Coastal Research, 68(sp1):57-64. Published By: Coastal Education and Research Foundation DOI: http://dx.doi.org/10.2112/SI68-008.1 URL: http://www.bioone.org/doi/full/10.2112/SI68-008.1

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Journal of Coastal Research

SI

68

57–64

Coconut Creek, Florida

2014

Effects of Sea Level Rise on the Intertidal Oyster Crassostrea Virginica by Field Experiments Joshua A Solomon†*, Melinda J Donnelly†, and Linda J Walters† †

Department of Biology University of Central Florida Orlando, FL 32817, U.S.A.

www.cerf-jcr.org

ABSTRACT Solomon, J.A.; Donnelly, M.J., and Walters, L.J., 2014. Effects of sea level rise on the intertidal oyster Crassostrea Virginica by field experiments. In: Huang, W. and Hagen S.C. (eds.), Climate Change Impacts on Surface Water Systems. Journal of Coastal Research, Special Issue, No. 68, pp. 57-64. Coconut Creek (Florida), ISSN 0749-0208. www.JCRonline.org

Sea level rise predictions for the next century range from 20 to 200 cm. Coupled with climate change-related increases in storm activity and associated alterations to sediment transport, estuaries and the organisms that live in them may be impacted. Along the eastern seaboard and gulf coast of the United States, Crassostrea virginica is an economically and ecologically important estuarine shellfish species. In an effort to understand potential effects of climate change on intertidal Crassostrea virginica, a novel method for manipulating inundation time of intertidal oysters was developed to examine effects of altering daily inundation time on sedimentation, predation, and competition. Called the oyster ladder, this method consists of suspending oyster shell as recruitment substrate at different elevations within the intertidal zone between mean low and mean high water. A six-week experiment was deployed during the peak of the 2011 oyster recruitment season at two sites within Apalachicola Bay, Florida. Data was collected on oyster recruitment, shell length, presence of sessile competitors, and sedimentation. Mean oyster shell length peaked at 95% time inundated, while recruitment peaked at 80% time inundation. Maximum sedimentation occurred at the highest inundation times (95% time inundation). The oyster ladder proved to be an effective tool for manipulating inundation times for C. virginica and suggests that sea level rise will have an effect on abundance, growth and survival of this of intertidal species. ADDITIONAL INDEX WORDS: Climate change, eastern oyster, marsh organs, submersion times, shellfish, benthic, Apalachicola.

INTRODUCTION The Intergovernmental Panel on Climate Change (IPCC) predicts sea levels will rise from 20 to 200 cm over the next century (Parris et al., 2012). Rising sea levels, coupled with climate change related increases in storm activity and associated alterations to sediment transport, will have unknown impacts on marine and estuarine organisms (Hoegh-Guldberg and Bruno 2010; Webster et al., 2005). The wide range of uncertainty in these predictions calls for research to investigate the effects of changing inundation and sedimentation on coastal species, especially sessile species residing in the intertidal zone. Crassostrea virginica (Eastern oyster) is an economically important shellfish species. Not only are these oysters important commercially, but they filter water at a rate of 6.8 L h-1, which has a positive effect on water quality and clarity (Kennedy 1996). Oysters also serve as ecosystem engineers, providing three-dimensional reef structure as habitat for mobile fauna and substrate for other sessile invertebrates and macroalgae (Kennedy, 1996; Coen, Luckenbach, and Breitburg 1999; Barber, Walters, and Birch, 2010). Intertidal oyster reefs serve ____________________ DOI: 10.2112/SI68-008.1 received 20 February 2014; accepted in revision 26 June 2014. *Corresponding author: [email protected] © Coastal Education & Research Foundation 2014

an additional role of helping to preserve shoreline vegetation, as well as the shorelines themselves, by significantly reducing wave energy (Manis 2013; Scyphers et al., 2011). Recent reports document that 85% of shellfish reefs have been lost globally and many of the healthy shellfish bastions that remain may soon be lost as well (Beck et al., 2011). Historically, the primary causes of these losses were anthropogenic, specifically pollution and overharvesting (MacKenzie 2007). These declines resulted in not only direct loss to the economy, but also the indirect loss of ecosystem services provided by oysters. With the already steep declines in shellfish reefs due to anthropogenic causes, the effects of sea level rise (SLR) pose an added threat that needs to be better understood. Inundation frequency is known to have important effects on intertidal species, their competitors and their predators, but we do not yet know what increased submersion times associated with SLR will have on these interactions. Predator avoidance resulting from daily fluctuations in water levels has been suggested as one of the reasons why intertidal oysters continue to exist, despite benefits of living subtidally where they can actively filter feed for longer durations (Dame, 1976). Many studies have confirmed inundation frequency as a driver of competition among intertidal sessile organisms, particularly among barnacles where abundances may relate to larval supply, preference, or predation, resulting in recruitment space being occupied

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Solomon, Donnelly, and Walters

_________________________________________________________________________________________________ (Boudreaux, Walters, and Rittschof, 2009; Grosberg, 1982; Miron, Boudreau and Bourget, 1999; Underwood, 1991;). Likewise, competition with other sessile invertebrates within the intertidal zone may undergo changes with increasing sea levels (Dayton, 1971). Hydrological changes associated with SLR will influence the spatial zones of competition between C. virginica and barnacles, the latter which preferentially settle in the areas of higher water motion (Bushek, 1988). Co-occurring with SLR there is an expectation of increased storm activity, which has the potential to negatively impact many coastal environments (Hoegh-Guldberg and Bruno, 2010; Webster et al., 2005). Winds associated with this increased storm activity have been shown to be positively correlated with increased suspended sediment loads, resulting in concentrations up to ten times higher than pre-storm loads, and taking up to four days to fall to background levels (Liu and Huang, 2009). Increased sediment loads have been shown to decrease settlement of oyster larvae by reducing available shell substrate on live oysters, increasing mortality in oyster spat less than one month old through abrasion of oyster larvae, or resulting in complete burial during storm events (Lenihan et al., 1999; Livingston et al., 1999; MacKenzie, 1983; Wall et al., 2005). Sediment loads of 8 g/L resulted in significant reductions of oyster settlement, but not barnacles (Boudreaux, Walters, and Rittschof, 2009). Our area of study, the Apalachicola region of the Gulf of Mexico, is dominated by subtidal oyster reefs and represents one of the few remaining relatively healthy oyster populations in the United States (Edminston, 2008; Ermgassen et al., 2013). Apalachicola Bay accounts for 90% of the commercially harvested oysters in Florida and 10% of the total oysters harvested in the United States (Livingston, 1984). The coverage of oysters within Apalachicola Bay is estimated at 10% of the total submerged area (Livingston, 1984). Of this total, intertidal oysters that are submerged approximately 65% of each tidal cycle, represent 6.5% of the total oyster coverage (M. Donnelly unpublished data). Ermgassen et al., (2013) identified Apalachicola Bay as the only estuary in the United States currently achieving full estuary filtration by C. virginica within one tidal cycle. Turner (2006) estimated that Gulf of Mexico oyster harvests in 2003 represented 69% by weight of all United States landings. Commercial harvesting and the ecosystem services provided by Apalachicola Bay oysters could be threatened by climate change in the northern Gulf of Mexico, especially when compounded with the historic causes of decline. HoeghGuldberg and Bruno (2010) indicated loss of habitat complexity associated with loss of oyster reefs as a result of climate change to be a chief concern due to the potential loss of associated biodiversity. Species potentially affected by loss of intertidal oyster reefs in Florida include commercially important species such as blue crabs, spotted sea trout, shrimp and stone crabs; these are species commonly found and harvested in Apalachicola Bay (Barber, Walters and Birch, 2010; Boudreaux, Stiner, and Walters, 2006; Edminston, 2008). Of the many impacts that climate change may have on intertidal oyster reefs, all depend on the amount of time a reef spends inundated. By investigating the effects of time submerged, predictions can be made about intertidal oyster reefs

into the future. The three important factors for intertidal oyster reef identified above: competition, predation, and sedimentation, can be studied through manipulation of elevations of experimental oyster reefs within the present intertidal zone. A method for manipulating percent time submerged with intertidal oysters was developed and referred to as the “Oyster Ladder”, see three-dimensional rendering, Figure 1. The oyster ladder was based on the marsh organ design of Dr. James Morris (Morris, 2007). Marsh organs were used to experimentally examine effects of inundation on salt marsh plants, particularly Spartina and Juncus genera (Morris, 2007). From these experiments, the marsh equilibrium model was developed to predict accretion or sediment loss of intertidal marshes. Here we use oyster ladders to investigate the effects of inundation time and sedimentation on intertidal C. virginica. Specifically, information at five levels of inundation was collected on: 1) recruitment and growth of C. virginica, 2) recruitment of sessile competitors, and 3) total sediment loads.

Figure 1. Oyster ladder design showing sediment traps and oyster restoration mats. Dimensions and mat numbers are included.

MATERIALS AND METHODS The Apalachicola National Estuarine Research Reserve (ANERR) encompasses 246,766 acres and is located in Franklin, Gulf, and Liberty Counties in the panhandle region of Florida (Edminston 2008). Two sites within the ANERR were used in our study, Figure 2. Both were chosen for their proximity to intertidal oyster reefs and for ease of access. Our first site (ANERR) was located beachside of the ANERR Education/Visitor Center in the town of East Point, and was 15 meters from a live intertidal oyster reef, Figure 2. The nearest subtidal oyster reef was the Cat Point oyster bar, 1.5 Km SSE of the experimental site. The second site (ASP) was located on the north side of St. George Island near the St. George Island State Park eastern boat ramp in East Cove. It was 10 meters from live intertidal oyster reefs. ANERR and ASP were 9 Km east and 21

Journal of Coastal Research, Special Issue No. 68, 2014

Sea Level Rise and the Eastern Oyster

59

_________________________________________________________________________________________________ Km southeast from the mouth of the Apalachicola River, respectively. In previous studies， turbidity differed between sites with ANERR having a Jackson turbidity value of 15.017.0, and ASP having a value of 0.0-12.0 (Edminston, 2008). The Florida Department of Environmental Protection (DEP) classified both sites as Class II waters (waters maintained for the designated use of shellfish propagation or harvesting) with sandy bottom sediments (Isphording, 1985; Edminston, 2008).

Figure 2a: Locations of sites ANERR (solid circles), ASP (open square) and previously mapped oyster reef within Apalachicola Bay, Florida. 2b: Inset of site ANERR to show location on the shoreline of Eastpoint, FL nearby to both intertidal and subtidal oyster reef. 2c: Inset of site ASP to show location within East Cove adjacent to intertidal oyster reefs. 2d: South-southwest view of ANERR oyster ladders, intertidal reef in foreground. 2e: West view of ASP oyster ladders showing intertidal reef in background. (Subtidal oyster layer courtesy of Apalachicola National Estuary Research Reserve, Intertidal oysters mapped by M. Donnelly)

Each oyster ladder consisted of 6 cm (two-inch) PVC, wood and galvanized steel framework, measuring 3.05 m long by 0.76 m wide, and standing 1.52 m tall, Figure 1. At each study site, five oyster ladders were deployed in a row two meters apart from one another, facing ninety degrees from the shoreline. Ladders were anchored with cinderblocks and rebar and were leveled with one another.

Each ladder suspended five oyster recruitment mats made of aquaculture-grade plastic mesh (Vexar) with 1.5 cm openings. Each mat measured 0.25 m2 and had thirty-six drilled, aged local oyster shells attached with 20 cm plastic zip ties (50 lb. test), Figure 3. Below each mat, a base of corrugated plastic was secured; this provided a stable, solid surface for the mat. Oyster shells were equally spaced in 6 x 6 arrays oriented perpendicular to the substrate, similar to the orientation of live oysters on intertidal oyster reefs (Grinnell, 1974; Stiner and Walters, 2008). Mean total available oyster shell substrate per recruitment mat (± SE) was estimated to be 5273 ± 122 cm (146 ± 3 cm per shell) (n=200 shells). Oyster recruitment mats were spaced apart equally vertically within the ladder at intervals of 33 cm, between the mean high tide and mean low tide water levels, Figure 1. Additionally, each mat was vertically aligned with corresponding mats on the other four ladders relative to water level. Oyster recruitment mats have been shown to provide suitable substrate for oyster recruitment (Birch and Walters 2012; Wall et al., 2005). Sediment traps were built from PVC (45.7 cm length, 7.6 cm diameter), the bottom end was capped, and the upper end held a 7.6 cm wide Nalgene funnel that held in place with a PVC coupling. The sediment traps had a 6:1 ratio of length to diameter, within the 5:1 – 10:1 range of recommended ratios to maximize sediment retention (Bloesch and Burns 1980). Funnel traps of this type have been determined to have 65% efficiency (Gardner 1980). Sediment traps were anchored to the oyster ladders using zip ties and wooden stakes, with their openings level to the associated oyster recruitment mat, Figure 1. Five sediment traps were installed on three ladders at each site (15 per site). Oyster ladders and sediment traps were deployed on 13 June 2011. The trial lasted for six weeks and coincided with annual peak oyster recruitment season in Apalachicola Bay (J. Harper pers. comm. ANERR 2011). Percent submersion times were determined using local tidal data for each mat height at each location. Monitoring of the oyster recruitment mats occurred at the end of the six weeks, after bringing mats to the laboratory. Examination was performed under a dissecting microscope. Live spat of C. virginica were counted on each side of the substrate shell and all live shell lengths were recorded using calipers. All other sessile organisms were identified to the genus level and counted. Sediment collection occurred three times during the experiment, at two weeks, four weeks, and at six weeks. For sediment collection, each sediment trap was removed from the oyster ladder and sediment was emptied into a plastic container. The sediment was taken to the Apalachicola National Estuary Research Reserve laboratory, placed inside a 1300 watt drying oven (Econotherm) at 85C, and dried to constant weight signaling that there was no additional evaporation occurring (Kenkel 2002). Once dry, the total weight of sediment was recorded for each two-week period. For analysis, sediment by trap was summed for the six-week total. Measurements were taken daily for 42 days on mean wind speed, maximum wind speed, air temperature, water temperature and salinity at our two sites. Mean wind speed, gust speed, and air temperature were taken for one minute each day facing ninety degrees from the shoreline adjacent to the oyster ladders


60


_________________________________________________________________________________________________ with a Kestrel 2000 Pocket Wind Meter. Water temperature and salinity were obtained adjacent to the oyster ladders using a waterproof digital thermometer (Alla 91000-051/F) and an optical refractometer (VEE GEE). Using JMP 9.0 (2010), analyses of oyster recruitment (live only), oyster shell length, other sessile invertebrate recruitment, and total sedimentation versus percent submersion times were completed using multiple regressions for linear data and quadratic multiple regressions for nonlinear data. Sites were considered blocks in our analyses. RESULTS Although the NOAA tide predictions suggested tidal range was very similar at our two sites, this was not the case. Percent time submerged at oyster ladders at the lower mat heights was similar between sites (95.2% time submerged for ANERR versus 98.8% for ASP); the mats highest on ladders (mat 5), however, had very different percent submergence times with 0.2% submergence at ANERR and 21% submergence at ASP, Figure 3. The variation in percent time submersion between the two sites was within 3 – 5% for mats 1 through 4, with variation of 20.8% at mat 5. Peak mean oyster recruitment did not occur at the highest percent time submerged, instead recruitment peaked at 82.8% submersion time (mat 2) at ANERR and 74.1% submersion time (mat 3) at ASP, Figure 4. Mean oyster recruitment (± SE) at the inundation level with the highest recruitment was 190.2 ± 21.4 live spat per mat (5.3 ± 0.6 per oyster shell) at ANERR. At ASP, peak values were 353.4 ± 41.3 live spat per mat (9.8 ± 1.1 per oyster shell). At ANERR mats 4 and 5 recruited no oysters; at ASP mat 5 recruited a total of five oysters. A quadratic multiple regression of percent time submergence versus oyster recruitment was significant (p < 0.0001). Not surprisingly, a significant site effect was documented (p = 0.0048). Mean oyster shell length increased with submergence time, Figure 5. At ANERR, the oyster mats directly above the benthos (mat 1) contained the largest spat (length: 0.8 ± 0.1 cm) at the end of six weeks; the oyster mats closest to the air-water interface (mat 5) contained no spat. At ASP, mat 1 contained the largest spat (0.7 ± 0.1 cm) and whereas a single mat 5 (21% submergence) contained five recruited oysters with a mean of 0.5 ± 0.1 cm. A linear multiple regression of percent time submergence significantly predicted oyster shell length (p < 0.0001). There was no significant site effect. These data included oysters which had recruited throughout the six weeks. Despite that, these results indicate that shell lengths were significantly greater with greater submergence time (Figure 6).

Figure 3. Percent submergence time by mat number for sites ANERR (solid circles) and ASP (open squares).

Figure 4. Mean number of oysters recruited per oyster recruitment mat ± SE by percent submergence time for sites ANERR (solid circles) and ASP (open squares).



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_________________________________________________________________________________________________

had a mean salinity of 19.9 ± 0.4 psu (range: 14- 24 psu) and ASP had a mean salinity of 23.2 ± 0.3 psu (range: 19 – 25 psu) over the six-week trial period.

Figure 5. Mean oyster shell length ± SE (cm) by percent submergence time for sites ANERR (solid circles) and ASP (open squares). No point appears for ANERR mat 5 as a result of no live oysters at that mat height.

Unlike oysters, barnacle recruitment increased with time submergence. The majority of recruitment occurred at site ANERR (98% of all barnacles counted), Figure 6. At ANERR, there were no barnacles found on the mats with the lowest percent submersion time, while the mats with the highest percent submersion time showed mean recruitment (± SE) of 2539.8 ± 683.2 barnacles per mat (70.4 ± 19.0 per shell). At ASP, one barnacle was found among the mats with lowest percent submersion time (mat 5). Mean barnacle recruitment at ASP was 2.6 ± 1.4 barnacles per mat (0.08 ± 0.04 per shell) for mat 1. A multiple regression of percent time submersion with the log of total barnacles was significant (p < 0.0001) with a significant site effect (p < 0.0001). Mean total sediment weight increased significantly with percent time submerged (p < 0.0001), Figure 7. At ANERR, the mean total sedimentation (± SE) ranged from 7.4 ± 3.0 g in traps adjacent to mat 5, to 39.3 ± 13.5 g at the lowest mats (mat 1) after the six weeks. The mat 5 sediment traps at ASP accumulated 3.0 ± 0.4 g and the lowest accumulated 13.5 ± 1.2 g of sediment. A multiple regression of total sediment weight with percent time submersion was significant (p < 0.0001) with a significant site effect (p < 0.0001), Figure 7. Most abiotic factors were consistent between sites, Table 1. Mean wind speed (± SE) at both sites was 3.4 ± 0.2 Kph (ANERR range: 1.0 - 6.3 Kph, ASP range: 0.6 - 6.3 Kph), with gusts up to 8.1 Kph at both sites. Air temperature was similar between sites with means of 31.5 C at ANERR (range: 27.5 33.3 ⁰C) and 31.0 ⁰C at ASP (range: 27.4 – 34.2 ⁰C). Water temperature had a mean of 32.6 ⁰C at ANERR (range: 30.6 – 35.7 ⁰C) and 32.5 ⁰C at ASP (range: 28.3 – 35.2 ⁰C). Salinity was the only abiotic variable that varied between sites. ANERR

Figure 6. Log of mean number of barnacles recruited per oyster recruitment mat ± SE by percent submergence time for sites ANERR (solid circles) and ASP (open squares). Mean barnacle recruitment differed between sites by two orders of magnitude.

Figure 7. Total sediment (g) captured by sediment traps ± SE by percent submergence time for sites ANERR (solid circles) and ASP (open squares).


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_________________________________________________________________________________________________ Table 1: Mean abiotic factors measured once daily adjacent to oyster ladders at each field site during the trial (n = 42 days). Mean Wind Gust Km h

-1

Mean Wind Speed

Air Temp.

Water Temp.

Salinity

Kph

⁰C

⁰C

psu

ANERR

5.5 ± 0.3

3.4 ± 0.2

31.5 ± 0.3

32.6 ± 0.2

19.9 ± 0.4

ASP

5.4 ± 0.2

3.4 ± 0.2

31 ± 0.2

32.5 ± 0.2

23.2 ± 0.4

DISCUSSION Future sea level rise is certain to have broad impacts on intertidal oyster reefs. By manipulating elevation within the intertidal zone, we demonstrated that oyster shell length, barnacle recruitment, and sedimentation all correlated positively with percent time submergence. Interestingly, oyster recruitment did not follow this pattern; instead it peaked at intermediate inundation times at both sites. The relative magnitudes of oyster recruitment, barnacle recruitment and sedimentation varied between the sites as a result of a multitude of pressures, including tidal fluctuations, predation, competition, and sedimentation. This success in identifying significant changes to the above factors makes the oyster ladder an effective tool for investigating the ecological effects of sea level rise on intertidal oyster communities. In Apalachicola Bay, oyster ladders showed oyster recruitment was greatest at intermediate submersion times (submerged approximately 80% of each tidal cycle). ASP experienced significantly more oyster recruitment than ANERR. This can be attributed to a number of biotic factors including competition and predation, as well as abiotic factors like sedimentation and salinity. It is important to note that there were more natural intertidal oysters at site ASP than at ANERR. It has been proposed that intertidal reefs in the southeastern United States are intertidal simply due to the local pressures of predation (Dame, 1976). Subtidal organisms that utilize the intertidal zone, such as mud crabs, are particularly voracious predators on oyster spat, but retreat with the tide to remain submerged (Dame and Patten, 1981). We observed mud crabs (Panopeus sp.) and blue crabs (Callinectes sp.), known predators of C. virginica, on oyster recruitment mats when submerged (Grabowski and Powers, 2004; Seed, 1980). On oyster ladders, oyster spat recruitment peaks may represent a balance between duration of submerged time for filter feeding, versus the safety from predation that oysters experience while exposed. Abiotic factors were unlikely to be drivers of the variation in oyster recruitment since water temperature, air temperature, and wind speed were consistent between sites. Although salinity varied between sites, it stayed well within the range (10 – 30 psu) that C. virginica grows in within the Gulf of Mexico (Berrigan et al., 1991). Surviving oysters at both sites grew consistently larger with increased submergence. This is not surprising since oysters can only filter-feed while submerged. It should be noted that although intertidal oysters submerged for more time grew larger, they were less numerous. This has important implications for

estuarine ecology since larger oysters are more efficient filter feeders (Walne, 1972). Larger size is also important from a reproductive standpoint as larger C. virginica have been shown to have higher reproductive output (Choi et al., 1993). ANERR experienced significantly more barnacle recruitment than ASP. Given that other abiotic factors were highly consistent, Table 1, and that the species of barnacles observed (Balanus eburneus, Balanus amphitrite) have optimal salinity ranges that include conditions observed at both sites (Dineen and Hines, 1992; Wang et al., 2008), increased barnacle recruitment may be explained by differences in the amount of protection from water movement provided by varying amounts of land within close proximity to the oyster reefs and experimental oyster ladders, Figure 2b and 2c (Bushek, 1988). Barnacle recruitment results in competition with oysters for settlement space (Bushek, 1988; Wall et al., 2005). This closely matched the pattern seen between ANERR and ASP, with higher barnacle counts associated with lower oyster recruitment and vice versa. ANERR experienced significantly more sedimentation than ASP. This is consistent with overland sediment transport from storm events entering the bay from the Apalachicola River, where ANERR is 12 km closer to the river mouth. Like barnacle recruitment, this may be related to the varying protection afforded by nearby dry land decreasing fetch, where surficial sediments can be suspended by storm-related winds (Chanton and Lewis, 2002). These storm events are expected to experience increased intensity and frequency with climate change (Hoegh-Guldberg and Bruno, 2010). These significant differences in sedimentation are an important factor in oyster recruitment, since increased sedimentation can result in loss of available substrate for settlement from clay sediment particles, and abrasion of new recruits by larger grains (Lenihan et al., 1999; Mackenzie, 1983; Wall et al., 2005). Since sedimentation has been previously identified as playing an important role in oyster recruitment and survival, developing and understanding a sediment grain size profile as it changes with inundation is also an important step towards predicting how changes in sedimentation may affect oysters (Lenihan et al., 1999, Livingston et al., 1999; MacKenzie 1983). CONCLUSIONS With projected sea level rise, intertidal oyster reef survival will be dependent upon on migrating landward (upslope) or recruitment of oysters upward (raising elevation of current reefs) at a pace that maintains optimal submersion times. In addition, when considering increased erosion occurring due to sea level rise, sedimentation will play an increasing role in deciding where future intertidal reefs will occur. With oyster habitats on the decline worldwide, it is an imperative that we understand the ongoing and future effects of sea level rise in order to prepare for future change, thereby being better prepared to conserve these economic and ecologically important organisms. By focusing on sedimentation, larval oyster recruitment, and the pressures of competition and predation, we can predict how rising sea level will impact the commercially and ecologically important C. virginica in Apalachicola, FL and the rest of the Northern Gulf of Mexico.



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_________________________________________________________________________________________________ ACKNOWLEDGMENTS Funding was provided by NOAA (EESLR-NGOM NA10NOS4780146; PI: Scott Hagen) and the University of Central Florida. We would like to thank J. Harper and Apalachicola National Estuary Research Reserve for access to facilities, J.T. Morris for experimental design insight, Florida Department of Agriculture for supplying local oyster shell, St. George State Park for site access, UCF Geotechnical Lab for access to equipment, and all of individuals who provided field assistance and statistical advice, including P. Sacks, J. Sacks, J. Conrad, R. Odom, M. Tye, J. Angelo, J. Weishampel, and G. Lewis. LITERATURE CITED Beck, M. W.; Brumbaugh, D.; Airoldi, L.; Carranza, A.; Coen, L. D.; Crawford, C.; Defeo, O.; Edgar, G. J.; Hancock, B.; Kay, M. C.; Lenihan, H. S.; Luckenbach, M. W.; Toropova, C. L.; Zhang, G., and Guo, X., 2011. Oyster reefs at risk and recommendations for conservation, restoration, and management. BioScience, 61(2), 107-116. Berrigan, M.; Candis, T.; Cirino, J.; Dugas, R.; Dyer, C.; Gray, J.; Herrington, T.; Keithly, W.; Leard, R.; Nelson, J. R., and VanHoose, M., 1991. The oyster fishery of the Gulf of Mexico, United States: A regional management plan. Gulf States Marine Fisheries Commission, Ocean Springs, Mississippi. Barber, A.; Walters, L. J., and Birch, A., 2010. Potential for restoring biodiversity of macroflora and macrofauna on oyster reefs in Mosquito Lagoon, Florida. Florida Scientist, 73, 4762. Birch, A. P. and Walters, L., 2012. Restoring Intertidal Oyster Reefs in Mosquito Lagoon: The Evolution of a Successful Model. TNC/NOAA Community-Based Restoration Partnership Final Report (NA10NMF4530081). Boudreaux, M. L.; Stiner, J. L., and Walters, L. J., 2006. Biodiversity of sessile and motile macrofauna on intertidal oyster reefs in Mosquito Lagoon, Florida. Journal of Shellfish Research, 25(3) 1079-1089. Boudreaux, M. L.; Walters, L. J., and Rittschof, D., 2009. Interactions between native barnacles, non-native barnacles, and the Eastern Oyster Crassostrea virginica. Bulletin of Marine Science, 84(1), 43-57. Bloesch, J., and Burns, N. M. 1980. A critical review of sedimentation trap technique. Swiss Journal of Hydrology. 42, 15-55. Bushek, D., 1988. Settlement as a major determinant of intertidal oyster and barnacle distributions along a horizontal gradient: Journal of Experimental Marine Biology and Ecology, 122(1), 1-18. Chanton, J., and Lewis, F. G., 2002. Examination of coupling between primary and secondary production in a riverdominated estuary: Apalachicola Bay, Florida, USA. Limnology and Oceanography, 47(3), 683-697. Choi, K. S.; Lewis, D. H.; Powell, E. N., and Ray, S. M., 1993. Quantitative measurement of reproductive output in the American oyster, Crassostrea virginica (Gmelin), using an

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