Studying the Environmental Impact of Small Craft Harbours

With hundreds of public and private marinas and small craft harbours dotting the British Columbia coast, it is no wonder that most residents don't give them too much thought. They are just another part of the geography and landscape of this part of Canada. But like many other development activities they can be a cause for concern from an ecological perspective. That's where The Centre for Aquaculture & Environmental Research (CAER) comes into the picture. CAER is a specialized centre for aquaculture and environmental research with staff from Fisheries and Oceans Canada, the University of British Columbia and the Vancouver Aquarium. With laboratory facilities located in West Vancouver, CAER is recognized internationally as a centre dedicated to innovative research and education in aquaculture and the marine environment.

Research scientist Steve Macdonald is the Senior Officer at CAER and leads a staff of 30 students, technicians and scientists. In recent years Dr. Macdonald, along with colleagues such as research biologist Dr. Herb Herunter, has taken on a number of coastal habitat research programs. One such program is a long-term examination of the environmental impact of small craft harbours.

The idea of using small craft harbours was a strategic choice because they are the responsibility of Fisheries and Oceans Canada  and Transport Canada. There are more than 1,000 of them across the country, with about 114 on the west coast. Most of the facilities have been developed and funded to support the inshore fishing industry and recreational boaters who live in the area.

A Ponar sampling device was used to grab sediment from harbour sites. Bottom samples from harbour sites were examined to identify infauna (animals living within the sediments), contaminants, and toxicity levels.

Credit: DFO

Dr. Macdonald: "Our program is generally interested in coastal development, not just the specific impact of small craft harbours.  However, they really are tiny petri dishes - microcosms that are representative of coastal development in general. Plus they are convenient for us to look at because of our jurisdictional responsibility and we have complete control over setting up experimental designs." Dr. Macdonald points out that, "This work is critical because you can't regulate something you don't understand. And the way we are tackling this project is to try to understand the ecological processes that go on in coastal environments that have been perturbed by harbour development. We are trying to get to the point where we provide informed advice to the folks who make decisions about how development will proceed."

There are a number of fundamental questions they are trying to answer. Such as: what sort of habitat alteration are these harbours imposing on the environment? And, are they being constructed in such a manner that they are at least ecologically benign or even perhaps creating habitat?

The first thing they did was review the number of harbours in existence, how old they were, what sorts of features they had, and how large they were. They decided to focus on three harbours, based on ease of access, and the range of breakwater types being used since breakwaters are invariably part of small harbour infrastructure. Their initial selection included  the harbours at Lund, Cowichan Bay and Port Hardy.

There are two major types of breakwaters. One is riprap or the rubble mound breakwater, which is simply a wall of  piled  rocks. Their construction will frequently smother soft-bottom communities but also create habitat for sub-tidal and inter-tidal communities that adhere to consolidated rock. Another type used in  deeper water is the floating breakwater. Some of these are made with old propane tanks or hulls of old vessels but the best ones are  concrete barges with draughts of three to four meters. They float with perhaps a  half meter of freeboard and involve a maze of anchors. These too can smother or at least  shade the bottom environment but their placement can also provide a substrate for aquatic communities.

The balance between the value of habitat that is lost to that being created is a complicated equation but ultimately will inform management outcomes. Harbour construction generally reduces unconsolidated habitats with soft-bottom communities and creates vertical environments more suited for communities that adhere to solid substrate. However, the communities created may be very rich and self-supporting.

By many measures the  breakwaters can result in additional productivity. Dr. Macdonald: "Both Herb and I have been impressed with the amount of growth that appears very quickly on breakwaters - as well as on docks. You will get animals that come and create habitat for other animals because there is new food and shelter. One of the things that I get a kick out of is just looking at how thick these mats (communities that grow along breakwaters and docks) are - and how the thickness of these mats changes with time and exposure. There is pretty good evidence that these mats, with their large invertebrate growths, are creating habitat for other animals. Harbour construction promotes the development of communities that engineer the ecosystem in their own right."

Credit: DFO

A sampling device attached to a long cable allows the collection of a three dimensional portion of the bottom environment from the research vessel. Once the retrieved material is filtered with a pump and water, a sample of macro invertebrates is ready for observation and identification with the aid of a microscope back in the laboratory.  Another devise takes scrapings off the rock breakwaters to get some idea of what is growing on the hard substrate. These are also sorted and identified. All in all, there is quite a demand for taxonomic knowledge, knowing how to identify large numbers of invertebrates from many different taxonomic groups.

Dr. Macdonald adds, "Our experimental design is based heavily on having reference sites adjacent to the harbour treatments where physical conditions such as exposure, salinity, current and temperature are similar but the harbour structures are absent. In other words, for every sample in the harbour, we take another at an undisturbed location close by, where physical characteristics are the same as the survey site. In addition to the influence of breakwaters we also consider boat launches, and docks and the urban development that services the marine  industry. As we gather information from an increasing number of reference locations a more complete picture emerges of the invertebrate communities in unperturbed shallow coastal sub-tidal environments around the Pacific Coast. Having a general sense of natural community structure and variability is a precursor to evaluating impact severity."

He also notes that they are developing an experimental design that they hope will allow them to - in addition to looking at the fine taxonomic detail in a few harbours - to do synoptic surveys. These surveys would sample with less resolution, focusing on indicators proven sensitive to habitat impact, freeing up the time to sample on a wider spatial and temporal scale. For example, species diversity or the presence of an easily sampled, identifiable and sensitive species may provide interpretable statistical patterns and have biological meaning over a broad area or time period. Both time and money can be saved in the process.

Dr. Macdonald noted, "We are not trying to stand in the way of the development. We know the value of harbours to the marine industry – and we also know with climate change and sea level rise there will be a lot of pressure to protect communities with riprap and dikes at the expense of natural lowlands. We hope to be in a position to make recommendations as to how to protect people's property and build the infrastructure necessary to service the recreational and coastal fishing industry while at the same time preserving the natural values that are initially responsible for attracting people to these coastal habitats."

With all the activity and development going on - above and below the water in small craft harbours – it is clear these surveys provide important feedback to policy makers as they wrestle with the twin objectives of protecting the marine environment and promoting sustainable use and development.

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