By Michael Parks
The function of a seaside sanctuary is to provide an environment as natural and safe as possible for the marine animal residents and their caregivers.
In any engineering project, you first have to know what it is that needs engineering and the functions that it’s intended to provide. In the case of a seaside sanctuary, this means a marine mammal coastal containment system that uses large mesh nets as barrier boundaries.
The first, and most important, factor in engineering a seaside sanctuary is site location. This is done in two stages. The first involves compiling as much geographical data as possible to find potential sites that meet certain general criteria used to rule in and rule out various locations. Once we have a short list of potential sites, the next stage involves field surveys at each site in order to gather information about a number of critical environmental factors. The final decision is made after all available information is collected, with each factor weighted for significance and then analyzed altogether.
Here are some of the elements that a sanctuary facility would need to offer:
As much secured space for the residents as possible
- Safety and protection from natural and human-generated hazards
- Specialized areas that provide caregivers and other professionals with access to the residents for health care and feeding
- A food storage processing/wet area
- Staff and scientist housing
- Places for public viewing and education that don’t intrude on the residents
- 24/7 security
The most important aspect of a seaside sanctuary that directly affects how the engineering is done is protection from extreme surface winds, waves and currents. While this is of utmost importance, there is also a need to be near enough to consistent underwater currents so that the environment can be kept clean by natural flushing. Balancing these two factors is an important aspect of the site selection process.
Netting is also one of the first items on the engineering list. Nets are used to make boundary lines and create the enclosure needed. The nets need to be attached at calculated intervals to the sea floor and to the shore surface above the highest expected sea level. The nets have mesh sizes (diamond-shape openings) that affect the amount of force the currents and waves will exert on the net as a marine structure. Determining that force is an important factor required for engineering an adequate-sized stationary barrier net. The net has to be custom built to the profile of the sea floor, transitioning to the intertidal zones, and high tide attachment points. It will be manufactured to fit this custom section and will then be attached all along the seafloor and up each side, using suitable anchoring methods.
Engineers will need to know the type of material to which the anchor/attachments will be attaching. For example, dead weights can be used in mud and hard sand areas, while rock bolts would be drilled into bed rock areas, and concrete/steel posts might be used at intertidal or high tide lines.
The final component of the boundary net is the flotation/buoy line/surface line to hold the net vertical, attach to shore points, and provide a visual boundary for the residents. This buoy line works in harmony with lead lines, in the bottom sections of the net, to hold the net taut.
Another important issue is the relationship between the sanctuary and the land. The facility will need access to utilities (unless it is fully self-sufficient), transportation and other amenities, all requiring different types of engineering. One way to minimize the impacts of land-based structures would be to use state-of-the-art engineered floating platforms. Floating and movable support platforms could provide solutions to many of the access issues and infrastructure needs of a sanctuary facility.
Finally, any seaside sanctuary facility will need the support of the nearby communities who understand and appreciate the importance and value of such a project.
Michael Parks is a staff consultant to The Whale Sanctuary Project.