Eco-engineering Penang’s Coastline

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There has been much success in turning Grey to Green.

As the human population rises, coastal areas become increasingly developed: more than 40% of the world’s population and 60% of the world’s largest cities are within 100km of the coast; by 2025, 70% will be living within 200km of the coastline.

Over half (17 out of 30) of the world’s largest cities are located in this zone. Asia, in particular, has shown some of the greatest intensification of coastal development, with 20 of the top 30 (67%) most populated coastal cities located there.

Penang Island is one of the fastest-growing and most densely populated places in the world, with a population of 752,800 and a density of 1,663/km2. The population on the 299km2-island has increased by more than 40% since 1970 and is projected to rise exponentially over the next 15 years.

Land reclamation in Penang began in the early 1800s under British administration, and recent large-scale coastal development projects have contributed to the alteration of the coastline to create more living space and to make way for transportation and infrastructure; at the time of writing, construction had begun on the first of a series of five artificial islands (three are still pending approval).

Various species of gastropods and limpets found in the tidal pools.

The Eco-engineering Phenomenon

Environmentalists have traditionally disfavoured city growth and urbanisation as these are often associated with the destruction of natural habitats and an increase in artificial habitats. For example, in the case of Penang, sandy and rocky beaches on the east coast are being rapidly replaced by coastal erosion protection structures such as seawalls, rock revetments and breakwaters. Environmentalists claim these replacements disturb natural habitats that are substantially more complex than artificial ones, and are usually blamed for the decrease in the abundance and diversity of coastal organisms.

Interestingly, in recent years there has been a turnaround in environmental thinking based on the recognition of urban biodiversity and the potential for landscapes to support valuable ecosystem services, which include provisioning, regulating, or supporting habitats and cultural services. Through appropriate planning and management, cities can be designed to have reduced ecological footprints and even promote urban biodiversity and conservation.

Ecological engineering, or ecoengineering, is an emerging field that integrates engineering criteria and ecological knowledge to create environmentally friendlier urban environments. A recent surge of literature is calling for a shift in the way artificial environments – often referred to as “grey” spaces – are perceived and designed to become “green” and “blue” spaces.

Different eco-engineering trials have been tried in coastal regions globally, largely at a few key hotspots e.g. Europe, the US and Australia. As a result, there is now an increasing number of “proof-of-concept” methods emerging for different types of coastal infrastructure.

Engineering Our Environment

The team at the Centre for Marine and Coastal Studies at Universiti Sains Malaysia (USM) has been working closely with key players in eco-engineering from all around the world for the past three years, and has replicated some coastal infrastructure methods in Penang in an effort to better manage its coast and conserve its biodiversity.

Drill-cored Pools

Eco-engineering in Penang started in 2015 with the drill-cored pools project. This method was first carried out on an intertidal granite riprap breakwater at Tywyn, West Wales. Holes were drill-cored into rocks in order to create tidal pools which are known to contain an incredible amount of biodiversity of flora and fauna compared to its surrounding emergent surfaces.

This method was cost-effective and easily carried out in Penang, and it achieved its purpose. The drill-cored pools created oases in the otherwise barren rock revetment surfaces. Green and brown algae flourished in these pools and among them were tiny eggs presumably laid by nerites. Other organisms found in the drill-cored pools were sea slugs, small fish, polychaetes, nerites, drill snails, clams, limpets, juvenile sea cucumbers, hundreds of shrimp and thousands of barnacles of different species. Interestingly, even moulted shells of crabs were also found in these pools, indicative that these creatures use the space for shelter and protection while moulting.

World Harbour Project

The World Harbour Project (WHP) was initiated by the Sydney Institute of Marine Science (SIMS) in 2014 with the aim to link, facilitate and enhance programmes of research and management in major urban harbours of the world.

Harbours and ports are extreme examples of inhospitable artificial structures, and in some cases, serve as hotspots for nonnative species which disrupt the coastal ecosystem. WHP explores the distribution and effects of artificial structures in global harbours and investigates materials and designs for the eco-engineering of harbours. Enhancements include the use of natural or eco-friendly materials, the addition of structural features (ridges, grooves and textures) and seeding with native habitat-forming species (e.g. algae, bivalves and coral).

Penang is involved in two of its components: green engineering and the social science survey. To incorporate the green engineering component here, tiles for organism settlement were imported from Sydney. These tiles were designed to have different degrees of complexity using eco-friendly materials. In 2016 a total of 70 settlement tiles were deployed on a port seawall and marina breakwater. Following the protocol provided by SIMS, half of these tiles were transplanted with native bivalves before they were deployed to be monitored for their growth and survival for the next one year.

Green algae and gastropod eggs observed in a tidal pool.

The size of transplanted oysters after eight months' of monitoring.

For Penang, local oyster spats (around 2cm in length) were chosen because they make good ecological engineers: their shells are used by other organisms and they have excellent water-filtration capabilities – a single adult oyster is capable of filtering up to 50 gallons of seawater a day. After nine months, the oyster spats tripled in size. Other organisms like shrimp, barnacles and gastropods of different species have also been found to co-habit these tiles as well as the shells of the transplanted oysters. Perhaps the most encouraging result was the discovery of hundreds of the economically important Asian green mussel spats living exclusively on the tiles placed on the artificial structures.

Flowerpot Project

The Flowerpot Project was first carried out by researchers from the University of Sydney at the seawall at Blackwattle Bay in Sydney, Australia. This method follows the same concept as the drill-cored pools, also known as flowerpots, to create tidal pools during low tide for coastal organisms such as algae, sea snails, star fish, crabs, sponges and small fish to colonise.

The size and shape of the flowerpots in Penang have been modified to suit local conditions. Fifteen of the locally engineered, eco-concrete pots were deployed in the first quarter of 2017 on a marina breakwater. After several months, similar mobile and sessile local organisms were observed using the pots.

Asian green mussel spats found in the grooves of the tiles and frames.

The textured settlement tiles transplanted with oyster spats.

The results achieved from the implementation of eco-engineering in Penang have so far been satisfactory and encouraging. The proof-of-concepts here suggest that eco-engineering can be applied under local circumstances after detailed evaluation on a case-by-case basis. The techniques are flexible in the way that they can be applied prospectively (during development/construction) or retrospectively (after development/ construction) on a range of budgets. This paves the way for larger-scale projects and the creation of whole ecosystems (such as artificial reefs) in the future in order to achieve more in conserving coastal biodiversity.

Considering that coastal development in Penang is on-going, there are plenty of opportunities that stakeholders can take advantage of, although it is cautioned that the eco-engineering approach should be employed together with other mitigation measures – for conservation, and not merely for the goal of development.

Dr Chee Su Yin is a senior lecturer at the Centre for Marine and Coastal Studies. Born and bred in Penang, she has made it her goal to discover novel approaches to develop coastal areas in a sustainable way in order for the ecosystem and the community to co-exist in equilibrium.



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