//
you're reading...

Book Review

Oh Where, Oh Where Should This Oyster Reef Go?

Paper: La Peyre MK, Serra K, Joyner TA, Humphries A. (2015) Assessing shoreline exposure and oyster habitat suitability maximizes potential success for sustainable shoreline protection using restored oyster reefs. PeerJ 3:e1317 https://doi.org/10.7717/peerj.1317

Like any other project, oyster reef restoration and shoreline protection projects require planning! But how do you get the most bang for your buck? You need to know where the need for protection is greatest and where the oysters will be able to thrive. That way, you can maximize the benefit of your restoration project, best utilizing whatever funds you have.

A little background first: Why restore oyster reefs at all? Because

Oysters = One Outstanding Organism!

Fig. 1: Oyster Reef—Source: Doug DuCap, https://www.flickr.com/photos/huggingthecoast/2232411772

Fig. 1: Oyster Reef—Source: Doug DuCap, https://www.flickr.com/photos/huggingthecoast/2232411772

Oysters provide a number of ecosystem services. As filter feeders, they improve water quality by removing pollutants, microalgae, and excess nutrients and contributing to sediment deposition. They build bars or reefs that buffer the shore from wave energy (Fig. 1). These reefs also provide habitat for many other organisms by acting as a hard substrate for settlement or a refuge. They attract fish that eat the oysters themselves or the critters hiding between their shells.

Unfortunately, in the last 100 years, 85% of oyster reefs have been gone the way of so many habitats: disappearance and degradation. Loss of oysters means loss of all those services they provide! Many studies have looked at oyster restoration projects and seen improvements in fisheries, water quality, etc. But the effect of oyster loss or restoration on coastal erosion is unknown, even though restoration projects are already being used for

Shoreline Protection

Coastal lands are eroding and being lost for a number of reasons, including sea level rise, coastal development, and removal of plants and other organisms that had previously stabilized shorelines (such as oysters?). Therefore, resources and effort are devoted to stabilizing shorelines to prevent further loss of these coastal lands, including marshes. While some methods of coastal protection utilize barriers such as seawalls, there is a recent focus on creating “living shorelines,” natural and sustainable systems such as oyster reefs. Louisiana, the site of this study, has rapidly eroding coastlines. They have already begun restoring oyster reefs to combat erosion, create habitat and improve water quality.

Oyster reefs buffer wave action, redirect water flow, and trap sediment while also bonding together and creating a calcium carbonate cement (essentially a kind of wall). Despite the many reasons that oyster reefs should prevent coastal erosion, there is not much evidence to support that. La Peyre et al. sought to determine whether they do and where they would likely be most successful based on two factors: 1) suitability for oysters and 2) shoreline orientation.

The “How” of the Study:

Fig. 2: Five sites of oyster reef restoration along the Louisiana coast. Source: La Peyre et al. 2015. https://doi.org/10.7717/peerj.1317

Fig. 2: Five sites of oyster reef restoration along the Louisiana coast. Source: La Peyre et al. 2015. https://doi.org/10.7717/peerj.1317

The researchers used a number of technologies, including GIS (Geographic Information Systems) and wave models to assess shoreline exposure and shoreline movement (is the shore advancing or retreating?) at five sites that have had oysters restored as well as control sites where no restoration had occurred (Fig. 2). At these sites and other randomly selected ones in Breton Sound estuary, LA, they evaluated shoreline exposure and habitat suitability.

They applied a habitat suitability index (HSI) to determine which areas are most likely to support oyster populations. That index (used in the Louisiana Coastal Master Plan 2012) incorporates bottom habitat and a few salinity metrics. The HSI maps show multiple years that vary by river discharge (which affects salinity). As salinity decreases, suitability for oysters also decreases. They then overlay those to find where oyster restoration efforts should be focused.

Erosion was Reduced!

Fig. 3: Shoreline movement based on exposure (low, intermediate, and high). Within each exposure category, sites that were restored (reef) are compared to controls (mud). Values are negative indicating shoreline erosion/loss. Less erosion is seen at restored sites. Source: La Peyre et al. 2015. https://doi.org/10.7717/peerj.1317

Fig. 3: Shoreline movement based on exposure (low, intermediate, and high). Within each exposure category, sites that were restored (reef) are compared to controls (mud). Values are negative indicating shoreline erosion/loss. Less erosion is seen at restored sites. Source: La Peyre et al. 2015. https://doi.org/10.7717/peerj.1317

Marsh erosion was indeed lower where reefs had been restored than at other sites without oyster reefs (Fig. 3). Where exposure was intermediate or high, the shoreline benefited most from restoration, with erosion reduced by 1.07 m/yr where reefs were restored compared to shoreline without reefs. Erosion was also reduced where exposure was low, but it had less of an effect since erosion was lower there to begin with.

Where Should Oyster Reefs Go?

Fig. 4: Shoreline and oyster suitability maps. Points show exposure levels. High and medium exposure sites are where restoration is needed most to minimize erosion. The tone of blue indicates habitat suitability for oysters (dark blue = more suitable). The three maps show different levels of river discharge: A) high, B) low, and C) average. The ideal placement of oyster reefs to have the greatest impact on shoreline erosion would be where exposure is high (green points) and the habitat is most suitable (dark blue). Source: La Peyre et al. 2015. https://doi.org/10.7717/peerj.1317

Fig. 4: Shoreline and oyster suitability maps. Points show exposure levels. High and medium exposure sites are where restoration is needed most to minimize erosion. The tone of blue indicates habitat suitability for oysters (dark blue = more suitable). The three maps show different levels of river discharge: A) high, B) low, and C) average. The ideal placement of oyster reefs to have the greatest impact on shoreline erosion would be where exposure is high (green points) and the habitat is most suitable (dark blue). Source: La Peyre et al. 2015. https://doi.org/10.7717/peerj.1317

I told you at the beginning: where the benefit is greatest and the oysters will thrive. Specifically, that means where? Given that oyster reefs do reduce marsh retreat on shorelines with intermediate and high exposure, it seems a good first step to focus on those levels of exposure. But it is important to consider the suitability of the habitat for oysters and choose sites where oysters are most likely to succeed. Maps (ex. Fig. 4) which overlay exposure and suitability are great tools for site evaluation and selection. And the variation in suitability based on river discharge seen in the three different maps shows how important it is to consider various scenarios and trade-offs when making decisions. It will be important to predict what future river discharge is likely or to prioritize selecting sites that will do well under any of the salinity scenarios.

Note: Marsh retreat was not reversed with restoration, so utilizing this shoreline stabilization strategy may need to be combined with strategies to manage other impacts beyond wave energy, such as sea level rise.

As always, there are many questions that need to be answered to improve our ability to site successful projects. To name a few, how does reef length, height, or shape affect success? How fast do oysters build the reef and is it more in expansion outward or upward? Stay tuned over the years as more restoration sites are created and monitored to answer these questions.

 

Because I found it cool, here’s a few links to publicly available databases the authors used to find high-resolution shoreline maps: Gulf of Mexico Coastal Ocean Observing System (GCOOS) and NOAA

Discussion

2 Responses to “Oh Where, Oh Where Should This Oyster Reef Go?”

  1. Thank you for this great review!

    Posted by Kayla Serra | April 3, 2016, 6:03 pm

Post a Comment

Instagram

  • by oceanbites 4 weeks ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 2 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 3 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 4 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 4 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 4 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 4 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 6 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 7 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 7 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 8 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 8 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 9 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 10 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 10 months ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com