Oyster reef

The term oyster reef refers to dense aggregations of oysters that form large colonial communities. Because oyster larvae need to settle on hard substrates, new oyster reefs may form on stone or other hard marine debris. Eventually the oyster reef will propagate by spat settling on the shells of older or nonliving oysters. The dense aggregations of oysters are often referred to as an oyster reef, oyster bed, oyster bank, oyster bottom, or oyster bar interchangeably. These terms are not well defined and often regionally restricted.

Oyster reef at about mid-tide off fishing pier at Hunting Island State Park, South Carolina

Degradation of oyster reefs

Oyster reefs were once common in estuaries around the world.[1] Within the last century there have been significant declines in the extent and condition of oyster reefs globally,[2] driven by overharvesting of oysters for food provision and lime production, and coastal degradation.[1] Boat wakes can cause oyster shells to be swept toward the shore, where they build up over time into exposed piles in which any remaining oysters will desiccate and die.[3] These piles may also isolate littoral areas from tides and currents, leading to further habitat degradation.[3] Laboratory experiments suggest that in areas of faster flow and higher amounts of suspended sediment, as would be seen in a high-traffic channel, the cyprid larvae of barnacles may outcompete larval oysters in settling onto substrate, a prerequisite for completing their respective life cycles.[4]: 40–48 

In the United States Crassostrea virginica, the eastern oyster, was a major reef builder in the Chesapeake Bay until the late 19th century. Because of overfishing, environmental degradation, and disease, populations of C. virginica underwent a drastic reduction in population size.[5] There is an established pattern connecting human fishing practices, such as dredging, to oyster population collapse across the globe. Besides the collapse of C. virginica reefs on the east coast of the United States, populations of the Olympia oyster, Ostrea lurida, on the western coast of the United States and the Sydney rock oyster, Saccostrea glomerata, of eastern Australia have both been heavily impacted by harmful fishing practices.[6] While most research has focused on temperate zones it is likely that significant declines have also been observed in tropical regions.[7]

The IUCN's Overall Risk Category assessment of the oyster reef ecosystem in southern and eastern Australia has labeled them as critically endangered.[8]

Oyster reef ecology

Natural oyster reefs are composed of living and dead oyster shells and provide important habitat for various species.[5] For example, the complex three-dimensional interstitial spaces within oyster reefs provide refugia for prey or juvenile species, which increases prey biomass and thereby enhances trophic transfer. Oyster reefs also stabilize shorelines by promoting sediment deposition and buffering wave energy, thereby allowing other habitats such as sea grass beds and marsh areas to form while simultaneously decreasing erosion of the shoreline.[9][10][11][12]

Ecosystem services

The filter feeding behavior of oysters can buffer against environmental degradation caused by human-induced eutrophication of estuary systems. Oysters feed on suspended phytoplankton and other organic matter. Disruption of the filter feeding by oysters can lead to a decrease in the elimination of organic matter from the water column and increase phytoplankton abundance. This in turn may lead to seasonal anoxia, which could increase mortality for other estuary animals, such as fish.[5]

Oyster reefs can also impact the carbon sequestration and excess nutrient uptake. Oyster reefs also stabilize shorelines by promoting sediment deposition and buffering wave energy, thereby allowing other habitats such as sea grass beds and marsh areas to form while simultaneously decreasing erosion of the shoreline.[9][13][14][15] Oyster reef habitats have been recognized as green infrastructure for shoreline protection.[16]

Restoration

Oyster reef restoration has accelerated in recent decades.[17] Oyster reef restoration projects often place the sanitized shells of dead oysters, concrete, or limestone pieces on a soft bottom to encourage oyster spat settlement.[10] Restoration of intertidal eastern oyster reefs can match natural densities of oysters and mud crabs, and recover oyster stability in about 6 years.[18] Additional benefits to restoring these habitats includes suppressing phytoplankton blooms via increasing filter feeding behavior,[19] increase nutrient sequestration and denitrification rates,[20] increase nekton biomass, and potentially increase commercial fishery value.[21] However, data on previously implemented restoration projects can be difficult to access, hindering future restoration efforts.[22]

See also
  • Rudists – extinct group of major reef-building bivalves in the Mesozoic Era

References
  1. Beck, Michael W. (2011). "Oyster Reefs at Risk and Recommendations for Conservation, Restoration, and Management". BioScience. 61 (2): 107–116. doi:10.1525/bio.2011.61.2.5. S2CID 4993209.
  2. Kirby, Michael Xavier (2004-08-23). "Fishing down the coast: Historical expansion and collapse of oyster fisheries along continental margins". Proceedings of the National Academy of Sciences. 101 (35): 13096–13099. doi:10.1073/pnas.0405150101. ISSN 0027-8424. PMC 516522.
  3. "Notes from the Field: Indian River Lagoon Oyster Reef Restoration Project" (PDF). The Nature Conservancy Indian River Lagoon Program. Retrieved 29 January 2023.
  4. Boudreaux, Michelle L. (2005). Native and Invasive Competitors of the Eastern Oyster Crassostrea virginica in Mosquito Lagoon, Florida (MSc thesis). Orlando: University of Central Florida. 532. Retrieved 30 January 2023 – via UCF STARS.
  5. Kirby, Michael X.; Miller, Henry M. (1 March 2005). "Response of a benthic suspension feeder (Crassostrea virginica Gmelin) to three centuries of anthropogenic eutrophication in Chesapeake Bay". Estuarine, Coastal and Shelf Science. 62 (4): 679–689. Bibcode:2005ECSS...62..679K. doi:10.1016/j.ecss.2004.10.004.
  6. Kirby, Michael (2004). "Fishing down the coast: Historical expansion and collapse of oyster fisheries along continental margins". PNAS. 101 (35): 13096–13099. Bibcode:2004PNAS..10113096K. doi:10.1073/pnas.0405150101. PMC 516522. PMID 15326294.
  7. Richardson, Marina A.; Zhang, Ya; Connolly, Rod M.; Gillies, Chris L.; McDougall, Carmel (23 June 2022). "Some Like it Hot: The Ecology, Ecosystem Benefits and Restoration Potential of Oyster Reefs in Tropical Waters". Frontiers in Marine Science. 9: 873768. doi:10.3389/fmars.2022.873768.
  8. Gillies, Chris L.; Castine, Sarah A.; Alleway, Heidi K.; Crawford, Christine; Fitzsimons, James A.; Hancock, Boze; Koch, Paul; McAfee, Dominic; McLeod, Ian M.; zu Ermgassen, Philine S. E. (2020-06-01). "Conservation status of the Oyster Reef Ecosystem of Southern and Eastern Australia". Global Ecology and Conservation. 22: e00988. doi:10.1016/j.gecco.2020.e00988. hdl:10536/DRO/DU:30139182. ISSN 2351-9894.
  9. La Peyre, M. K.; Furlong, J.; Brown, L. A.; Piazza, B. P.; Brown, K. (2014). "Oyster reef restoration in the northern Gulf of Mexico: extent, methods, and outcomes". Ocean & Coastal Management. 89: 20–28. doi:10.1016/j.ocecoaman.2013.12.002.
  10. Brown, L. A.; Furlong, J. N.; Brown, K. M.; La Pyre, M. K. (2014). "Oyster reef restoration in the northern Gulf of Mexico: effect and artificial substrate and age on nekton and benthic macroinvertebrate assemblage use". Restoration Ecology. 22 (2): 213–222. doi:10.1111/rec.12071. S2CID 84109311.
  11. Dillon, K. S.; Peterson, M. S.; May, C. A. (2015). "Functional equivalence of constructed and natural intertidal eastern oyster reef habitats in a northern Gulf of Mexico estuary". Marine Ecology Progress Series. 528: 187–203. Bibcode:2015MEPS..528..187D. doi:10.3354/meps11269.
  12. George, L. M.; De Santiago, K.; Palmer, T. A.; Pollack, J. B. (2015). "Oyster reef restoration: effect of alternative substrates on oyster recruitment and nekton habitat use". Journal of Coastal Conservation. 19: 13–22. doi:10.1007/s11852-014-0351-y. S2CID 54732481.
  13. Brown, L. A.; Furlong, J. N.; Brown, K. M.; La Pyre, M. K. (2014). "Oyster reef restoration in the northern Gulf of Mexico: effect and artificial substrate and age on nekton and benthic macroinvertebrate assemblage use". Restoration Ecology. 22 (2): 213–222. doi:10.1111/rec.12071. S2CID 84109311.
  14. Dillon, K. S.; Peterson, M. S.; May, C. A. (2015). "Functional equivalence of constructed and natural intertidal eastern oyster reef habitats in a northern Gulf of Mexico estuary". Marine Ecology Progress Series. 528: 187–203. Bibcode:2015MEPS..528..187D. doi:10.3354/meps11269.
  15. George, L. M.; De Santiago, K.; Palmer, T. A.; Pollack, J. B. (2015). "Oyster reef restoration: effect of alternative substrates on oyster recruitment and nekton habitat use". Journal of Coastal Conservation. 19: 13–22. doi:10.1007/s11852-014-0351-y. S2CID 54732481.
  16. Arkema, Katie K.; Guannel, Greg; Verutes, Gregory; Wood, Spencer A.; Guerry, Anne; Ruckelshaus, Mary; Kareiva, Peter; Lacayo, Martin; Silver, Jessica M. (2013-07-14). "Coastal habitats shield people and property from sea-level rise and storms". Nature Climate Change. 3 (10): 913–918. doi:10.1038/nclimate1944. ISSN 1758-678X.
  17. Duarte, Carlos M.; Agusti, Susana; Barbier, Edward; Britten, Gregory L.; Castilla, Juan Carlos; Gattuso, Jean-Pierre; Fulweiler, Robinson W.; Hughes, Terry P.; Knowlton, Nancy; Lovelock, Catherine E.; Lotze, Heike K.; Predragovic, Milica; Poloczanska, Elvira; Roberts, Callum; Worm, Boris (1 April 2020). "Rebuilding marine life". Nature. 580 (7801): 39–51. doi:10.1038/s41586-021-03271-2. ISSN 1476-4687. PMID 32238939. S2CID 233279016.
  18. Smith, Rachel S.; Lusk, Bo; Castorani, Max C.N. (5 April 2022). "Restored oyster reefs match multiple functions of natural reefs within a decade". Conservation Letters. 15 (4). doi:10.1111/conl.12883. S2CID 247990521.
  19. Gedan, Keryn B.; Kellogg, Lisa; Breitburg, Denise L. (1 July 2014). "Accounting for Multiple Foundation Species in Oyster Reef Restoration Benefits". Restoration Ecology. 22 (4): 517–524. doi:10.1111/rec.12107. ISSN 1526-100X. S2CID 22032465.
  20. Kellogg, M. Lisa; Cornwell, Jeffrey C.; Owens, Michael S.; Paynter, Kennedy T. (22 April 2013). "FEATURE ARTICLE Denitrification and nutrient assimilation on a restored oyster reef". Marine Ecology Progress Series. 480: 1–19. doi:10.3354/meps10331.
  21. Humphries, Austin T.; Peyre, Megan K. La (25 August 2015). "Oyster reef restoration supports increased nekton biomass and potential commercial fishery value". PeerJ. 3: e1111. doi:10.7717/peerj.1111. PMC 4556142. PMID 26336635.
  22. La Peyre, Megan; Furlong, Jessica; Brown, Laura A.; Piazza, Bryan P.; Brown, Ken (1 March 2014). "Oyster reef restoration in the northern Gulf of Mexico: Extent, methods and outcomes". Ocean & Coastal Management. 89: 20–28. doi:10.1016/j.ocecoaman.2013.12.002.
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