A variety of ecological enhancement units are now commercially available. Enhancements can also be constructed using information and resources that are freely available online.
Ecological enhancement options:
Enhancement tiles are precast concrete units that can be affixed to seawalls. Tiles have been developed by research groups in Singapore, the UK, and Australia to meet two different objectives: (1) enhancing biodiversity, and (2) enhancing native bivalve assemblages.
(1) Enhancing biodiversity
Tiles for enhancing biodiversity on seawalls were first developed by Dr. Lynette Loke and the Experimental Marine Ecology Lab at the National University of Singapore, led by Dr. Peter Todd. Studies in Singapore have consistently demonstrated higher biodiversity as a result of Dr. Loke’s tiles. This effect has been maximized through an iterative process of identifying the most effective design features and scale.
Methods for constructing tiles like those from Singapore are present in published work by Dr. Loke and her co-authors:
- Ecology (2016) Vol. 97, Iss. 2, pp. 383–393
- Raffles Bulletin of Zoology (2016) Supplement No. 32, pp. 1–10
- Journal of Experimental Marine Biology and Ecology (2017) Vol. 492, pp. 133-120 (may require purchase; an “in press” version is available for download here)
Dr. Loke has also developed a software program for generating tile designs called Complexity for Artificial Substrates (CASU). It produces ouput files that can be used directly in AutoCAD or other programs to produce tiles. Here’s the link that will download CASU. The user manual can be found here. Development and testing of the program is reported in Dr. Loke’s 2014 publication in PLOS ONE. Additional background information about ecological definitions of complexity and their relationship to diversity is can also be found in this 2015 publication in Ecological Engineering.
Tiles have also been developed in the UK by Artecology, a collaboration between ecological consultants Arc Consulting and public artists Eccleston George, and are now commercially available. Effects of Artecology’s tiles on biodiversity are currently being assessed by University of Glasgow researchers; Preliminary results from that study are available here.
(2) Enhancing native bivalves
The World Harbour Project (WHP) has developed tiles aimed at enhancing native bivalve assemblages. This work was done in partnership with Reef Design Lab, a not for profit design studio and think tank based in Melbourne, Australia.
WHP/Reef Design Lab tiles are commercially available through the Reef Design Lab website: http://www.reefdesignlab.com/seawalls/.
In 2016 and 2017, WHP conducted an experiment in 15 cities around the world (!!!) to test whether the tiles effectively enhance bivalve assemblages and reduce non-indigenous species. Results from that experiment should be available soon. In the meantime, a synopsis of the project can be found here. It also involved seeding treatments, which we discuss further on the Seeding page of this site.
Monitoring and quantifying effectiveness
If you are planning to incorporate enhancement tiles into a project, it’s important to do so in a manner that objectively evaluates their effectiveness and impact.
Tiles are a relatively new technology, and their effects to date have been evaluated in a relatively few locations and for limited periods. By deploying tiles as experiments (with proper controls and levels of replication), you can contribute to the growing body of science on seawall enhancements and help advance our understanding of factors that influence their effectiveness.
We are happy to discuss tile deployment and experimental design – please don’t hesitate to drop us a line!
Ongoing monitoring and fieldwork required to assess the effectiveness of tiles may be achieved through partnerships with researchers in your area (World Harbour Project provides an excellent network for establishing such partnerships), or can be incorporated into tasks of contracted environmental consultants.
For new seawalls or bulkheads and for major retrofits, textured concrete slabs provide an ideal alternative to the homogeneous surfaces from concrete poured in place.
Elliott Bay Seawall Project
The Elliott Bay Seawall Project (Parsons Corporation) in Seattle is the largest project to date employing textured slabs. Slabs were designed by Haddad|Drugan and informed by research from the University of Washington. They form 1.2 km of continuous textured substrata that mimics surfaces of local taxa, including barnacles, mussels, anemones, sea stars, and rockweed. The slabs will be monitored over time to quantify settlement and diversity of intertidal organisms.
Pre-fabricated textured slabs
Pre-fabricated textured slabs are commercially available from ECOncrete, a small firm that has developed a proprietary concrete mix that is pH-neutral, which can facilitate recruitment and biogenic buildup (link). Ecological responses to ECOncrete’s formula have been assessed through field experiments led by the company’s CEO, who is also a scientist, Dr. Shimrit Perkol-Finkel, and are reported in peer-reviewed publications (listed on Dr. Perkol-Finkel’s ResearchGate page). Textured slabs produced by the company are called ECOncrete® Enhanced Seawall Panels. In a 2017 study, four panels affixed to a smooth, vertical seawall in Marina Herzliya, Israel were found to increase species diversity relative to adjacent seawall surfaces after 22 months.
Importance of monitoring
Textured concrete slabs are a relatively new technology. If you are planning to employ them in a project, an accompanying monitoring plan that characterizes species composition over time and records any settlement by non-indigenous species is essential. This may be done as part of contracted environmental consulting work for the project, or via partnerships with researchers in your area (World Harbour Project provides an excellent network for establishing such partnerships).
Ideally, slabs are installed experimentally with proper controls, or in a before-after-impact-control design, in which case monitoring data can contribute to the growing body of peer-reviewed literature on seawall enhancements. At minimum, presence and percent cover of non-indigenous species on textured slabs should be periodically assessed and compared with smooth vertical surfaces the same area.
If you have any questions, we’re happy to discuss – please don’t hesitate to drop us a line!
Artificial rock pools are enhancement units that retain seawater at low tide and increase diversity on seawalls, bulkheads, and breakwaters. They mimic tide pools, which are an important feature of natural rocky shores.
Researchers have used several approaches for creating rock pools on artificial shorelines previously. Approaches differ depending on the type of project.
Rock pools for…
Masonary seawalls (new construction)
For new intertidal structures with masonry construction, an approach similar to the employed by Dr. Gee Chapman and Dr. David Blockley in a 2009 study may be ideal. Chapman and Blockley (2009) formed rock pools by omitting sandstone blocks during construction of a seawall in Sydney Harbor. Open spaces were then fitted spaces with sandstone shelves that extended horizontally from the wall.
Existing vertical seawalls
On existing vertical seawalls and bulkheads, rock pools of different sizes can be developed through:
(1) Drill coring: Small rock pools can be generated by drill coring directly into the structure, as described in a 2014 study by Dr. Louise Firth and colleagues. Firth et al. (2014) used a diamond-tipped drill corer to extract 15 cm diameter cores of two different depths (12 cm and 5 cm) from a granite seawall in Tywyn, UK. These dimensions were selected to mimic rock pools on nearby natural rocky shores (as discussed by Evans et al. 2016), but could be adjusted according to local conditions and particular species of interest. For instance, in a 2010 study, Dr. Gustavo Martins and colleagues selected a 12 mm diameter based on measurements of naturally-occurring pits on volcanic rocky shores in the Azores. Their study additionally focused on enhancing limpets, which used pits that closely match their shell dimensions (10-15 mm diameter).
(2) “Flower pots”: Larger rock pools can be integrated into existing vertical intertidal structures through the use of concrete structures that resemble flower pots. This approach was developed by Mark Browne and Gee Chapman and initially described in their 2011 study. Since natural rockpools of different sizes support different assemblages of organisms, “flower pots” constructed by Browne and Chapman (2011) were modified to be either 38 cm or 22 cm deep (all were 36 cm across at the top).
(3) Vertipools: Similar to “flower pot” pools in function, Vertipools are the creation of UK-based Artecology, a collaboration between ecological consultants Arc Consulting and public artists Eccleston George. Artecology offers several Vertipool models commercially, which you can peruse here.
Breakwaters (existing or new construction)
Rock pools can also be incorporated into breakwaters or other shoreline structures comprised of riprap using either commercially available or open-access (DIY) stand-alone enhancement unit.
(1) ECOncrete® Tide Pools are commercially available rock pools made of ECOncrete’s “bio-active” proprietary concrete mix (link). Projects utilizing ECOncrete® Tide Pools include Living Breakwaters on the south side of Staten Island that were designed by the landscape architectural firm, SCAPE.
(2) BIOBLOCKs are 1.5 m × 1.5 m × 1.1 m concrete blocks that include rock pools, among other enhancement features. BIOBLOCKs were designed by academics and their design is presented in Firth et al. (2014).
Importance of tidal height
While rock pool units are well established enhancement tools, care should be taken to ensure they are well positioned with respect to tidal height. Units placed too high in the intertidal zone, where they are only occasionally submerged by tides, will collect freshwater and have lower diversity. Accumulation of freshwater may be of particular concern in the tropics and in cities where mosquito-borne diseases pose a public health risk. Pools should be placed where the maximum amount of time between tidal submersion is less than the time required for mosquito larvae to develop (1-3 days in some areas). Units placed too low on the shoreline, particularly if just below the lowest low tide, will be of limited value.
As will all ecological enhancements, monitoring of rock pool units is essential to ensure they are effective and are not promoting establishment of non-indigenous species. This can be done by consulting with commercial providers of pre-fab units (where used), through partnerships with researchers (World Harbour Project provides an excellent network for establishing partnerships), or through contracted environmental consultants.
Got questions? Drop us a line!
UNDER CONSTRUCTION: More info about stand-alone modules coming soon!
Type of larger enhancement units:
- BIOBLOCKS (Open access)
- ECOncrete® Ecological Armoring Units (Commercially available)
- Reef Balls®TM (Commercially available)
- ReefDesignLab 3D Printed Reefs (Commercially available)
- ReefDesignLab Easy Drop Units (Commercially available)