By Justin Crane, FAIA

“The edge of the sea is a strange and beautiful place.” –Rachel Carson, The Edge of the Sea

Waterfronts are ecologically vital opportunities for bio-positive design. Meaningful steps are being taken to steward, protect, and reinforce some of the most obviously productive ecosystems such as forests and wetlands; however, we also must act on opportunities at seemingly marginal areas such as the edge of the sea.

At first glance, the tidal zone appears to be a barren expanse of sand or rock. Indeed, the ocean’s edge is a tough place to live, seemingly fit for a limited group of creatures that can survive in breaking waves that strike with the force of two tons per square foot, constantly advancing and receding tides, and the harsh extremes of the land world where plants and animals are exposed to heat and cold, wind, rain, and drying sun. Yet among these seemingly desolate stretches of rock or sand are an impressive array of plants and animals that are critical to both marine and terrestrial food webs.

Between the equator and 30 degrees latitude are the especially fecund coastal ecosystems of mangrove swamps and coral reefs. At higher latitudes, coasts that are not estuarine are typically either sandy or rocky. And just as Cape Cod forms a rough zoological boundary between the warm southern waters of the Gulf Stream and cold northern waters, New England’s coast is a transitional zone with both sandy beaches, like those to the south, and rocky shores like those to the north. As a result, the hard edges of our wharves and harborwalks provide opportunities to support flora and fauna that are native to the rocky edges of New England.

It’s worth noting here that, even in 1955 when Carson wrote The Edge of the Sea, scientists understood that ecological boundaries were creeping steadily north:

Curious changes have been taking place, with many animals invading this cold-temperate zone from the south and pushing up through Maine and even into Canada. This new distribution is, of course, related to the widespread change of climate that seems to have set in about the beginning of the century and is now well recognized – a general warming-up noticed first in arctic regions, then in subarctic, and now in the temperate areas of northern states.

While the current rate of change will likely be exceptionally harmful, any bio-positive design at the water’s edge must acknowledge that the shore is a place that is forever changing – between phases of the moon, through seasons, years, and geological eras. Opportunities for design at urban edges start with an understanding of marine and ecological flows and functions.

Marine bio-positive design starts by studying the flora and fauna that existed at the site before human interventions, acknowledges the need to reinforce life that remains (or eradicate invasive species), then uses this research to inform the design of built objects to facilitate the natural activities that could occur at the site. An exceptional recent example is Seattle’s new seawall, engineered by Parsons, which supports restoration of the chinook salmon populations that swim through Elliott Bay on their way to the Duwamish River and other waterways. The seawall design includes translucent sidewalk panels in the overhanging walkway above to allow for sunlight and plant growth below; a textured surface to the wall promoting algae growth that provides food for salmon; and “rock mattresses” at the bottom providing homes and hiding places for marine organisms.

At CambridgeSeven, we’re working with clients to design waterfront sites that reinforce their coastal ecologies while also making these sites more resilient and educational. As part of our comprehensive campus plan for the New England Aquarium, we’re re-imagining Central Wharf and the Harborwalk to improve resiliency; while at the Roux Institute at Northeastern University, in Portland, ME, we’re addressing resiliency and restoring the coastal edge along the shore of Casco Bay. Following is our list of strategies for designing harbor edges for sea life:

• Form complex geometry: Nooks and crevices provide microclimates in which a variety of plants and animals can live, and in which animals can hide from predators. While barnacles and mussels stick to almost any solid material, the plants and animals that follow–such as snails and then crabs, sea stars and worms–require more complicated surfaces to create refuge from breaking waves and predators.
• Specify natural and locally sourced materials: Scientific studies have shown that artificial substrates tend to favor invasive species in the long-run, perhaps because the new surface type provides a level playing field on which new species can compete with native animals. Natural and familiar materials reinforce the existing ecological balance.
• Create pools: Ledges at varying heights between high and low tide will capture sea water in tidal pools and host a special subset of sea life, such as crabs, anemones and sponges.
• Restore Tidal Currents: Creating opportunities for increased tidal action improves nutrient flows that will nourish plant and animal life – as an example, this can be done by restoring tidal creeks with the side benefit that the cut may be used as fill elsewhere for lifting buildings above sea level rise.

• Design pedestrian paths: Intentionally created trails and overlooks will keep visitors from tramping on delicate organisms while providing opportunities to safely experience or view the water’s edge from new levels and angles.
• Build higher: Design for heights that will allow organisms to climb to a higher zone as sea levels rise. Rocky shore zones are distinguished by their exposure to elements, with the highest being the splash zone typically dominated by lichen, the high intertidal zone at mid-level, and the lower intertidal zone dominated by algae at the bottom. As the climate changes, slow-moving flora and fauna will need zones of retreat to maintain this balanced ecosystem.
• Plant for the full ecosystem: Above and adjacent to the seawalls, grow indigenous coastal vegetation, including pollinator gardens at building terraces and roofs, or Miyawaki forests including mosses and lichens to support animals that participate in the coastal food chain. Planted zones adjacent to the sea edge can also help to filter and clean runoff from urban ground surfaces

  

   

• Protect sea life and shorebirds, such as through lighting that is shielded so that it is not directly visible from the shore and emits long wavelengths of light – appearing amber, orange, or red in color. These colors are less disturbing to sea turtles and attract fewer insects – causing less disturbance to the waterfront food chain. Bird-friendly glass should be used in buildings and landscape elements such as guardrails.
• Elevate the building: Locate heavily occupied spaces and critical services above the predicted 2070 storm surge level, and provide breakaway panels allowing for intentional flooding to minimize damage to the building and adjacent structures from storm surges – all while creating more views to the ocean and creating new, sheltered public gathering spaces.

Finally, we should celebrate – through views to and from sea walls, harborfront interpretive graphics, and controlled opportunities to access the water – the abundance of life at the edge of the sea. If we welcome and highlight the plants and animals living next to and around our waterfront architecture, we can create a new generation of advocates for restoring our marine ecosystems.

All too often, people think of the shore as desolate stretches of sand or piles of rocks; our urban waterfront architecture too often neglects the moment when water meets land. However, this zone is a critical link between terrestrial and marine life and a “strange and beautiful place” for which we at CambridgeSeven are collaborating with clients to create designs for a range of waterfront conditions – from Gloucester’s Harborwalk to granite wharves at the New England Aquarium to a beach-front lab on Virginia Key in Florida – each inspired by the sites’ specific ecological needs and unique place at the edge of our world.