Centre of Expertise for Aquatic Habitat Research: Exploring the Connections Between Habitat and Aquatic Communities

Until recently, it was assumed that rocky structures introduced into coastal environments destroy fish habitat within their footprint. Now a Fisheries and Oceans Canada (DFO)-led research team is exploring the validity of this assumption by studying aquatic communities around structures in DFO's Gulf Region waters.

"This project is in response to a major issue for habitat managers across the country; namely, how do we assess changes to the productive capacity of coastal areas that experience development?" says DFO research scientist and project leader Dr. Simon Courtenay.

Team member Jordan Musetta-Lambert, an M.Sc. student at the University of New Brunswick, compiled a database of all the rocky structures built in Gulf Region waters over the past 20 years. The database will be used to select structures of similar construction but different ages to determine how long it takes to establish a stable community of plants and animals. The team, including researchers from DFO's Gulf, Newfoundland and Pacific regions, will then compare each existing community to the community that would have been there if that breakwater or other structure had not been built.

In 2010, Dr. Courtenay's team will survey the plants and animals living on and around human built rocky structures of different ages. Measurements of the aquatic community will also be made at increasing distances away from structures to determine the estimated size of the affected area relative to the physical disturbance footprint. Since biological communities change seasonally in the southern Gulf of St. Lawrence, sampling will take place in the spring, summer and fall. The findings will provide the Small Craft Harbours program and habitat managers with critical information on whether rocky structures built in the coastal environment result in larger, smaller or just different biological communities. This knowledge will aid in the design of breakwaters, coastal armouring and other rocky structures that minimize the loss of habitat, and the development of effective mitigation and compensation measures — how to avoid the loss of habitat to development and how to compensate for unavoidable loss.

The Centre of Expertise for Aquatic Habitat Research (CAHR) explores habitat-population linkages

The project is one of several being carried out under the auspices of the Centre of Expertise for Aquatic Habitat Research (CAHR), a DFO virtual Centre of Expertise (COE) established in 2008 to coordinate and conduct strategic research on habitat and population linkages. The centre's goal is to better understand the connections between habitat productive capacity, population productivity and ecosystem resilience — how vulnerable a species or habitat is to damage combined with its ability to recover from damage — and the implications of these linkages for habitat management.

CAHR mobilizes expertise across the country on broad aquatic habitat issues of national significance that are common to many or all of DFO's regions. CAHR's research addresses three focal areas:

• cumulative effects: quantifying and calibrating effects of human-induced and natural changes to habitats and the aquatic resources they support;
• mitigation and compensation: assessing the effectiveness of mitigation and compensation policies for human activities negatively affecting habitats; and
• vulnerable marine ecosystems (VMEs): providing science support in aid of VMEs in the high seas.

Cumulative effects of multiple stressors

Aquatic habitat stressors range from physical, chemical and environmental to human development of shoreline habitat. "Each stressor may be reasonably well studied in isolation, but the combined effects on habitat are almost completely unknown. This is a nationally and internationally significant issue for which there are no readily identified solutions" says CAHR Director Dr. Robert Gregory.

Part of CAHR's mission is to find ways to study those cumulative effects, which is scientifically much harder than investigations of single stressors, particularly when those effects are very dissimilar.

"Watersheds are one example for which understanding the effects of multiple stressors is especially important," notes Dr. Gregory. "A question that habitat managers encounter regularly when reviewing development proposals is: how many small streams and creeks can be taken away before the whole watershed becomes non-functional? That type of habitat change can represent the proverbial ‘death of a thousand cuts' for a formerly productive watershed."

Mitigation and compensation research

Mitigation and compensation research explores effective ways to avoid the "harmful alteration, disruption or destruction" (HADD) of fish habitat. When a particular HADD is unavoidable, one of the guiding principles of DFO habitat policy applies — "no net loss of the productive capacity of fish habitat." "No net loss" seeks to balance habitat losses with newly created and/or restored fish habitat, known as compensation.

"There are significant demands on science to provide advice to habitat managers regarding what comprises effective compensation for lost habitat. CAHR's aim is to determine empirical relationships to guide compensation plans," says Dr. Gregory. "The question is what constitutes good replacement…the ideal is like-for-like, but that isn't always possible. We often need to determine how much habitat of another type is necessary in order to be effective compensation for the lost habitat. This can be a tough issue, especially in highly productive areas."

In Newfoundland, DFO research led by biologist Keith Clarke is exploring the effectiveness of compensatory habitat built to replace salmonid habitat destroyed during the construction of the Granite Canal Hydroelectric Development. The lost habitat was primarily used by landlocked Atlantic salmon (ouanainche) and, to a lesser extent, brook trout.

Pre-development surveys suggested that the habitat destroyed was used extensively for spawning, particularly by salmon. To compensate for this loss, Newfoundland and Labrador Hydro (now Nalcor Energy) constructed a 1.6 kilometre channel (Compensation Creek) mainly to supply spawning habitat, which was very limited in tributaries of the downstream reservoir, Meelpaeg Lake. Researchers are monitoring the movements of fish between the creek and the reservoir to determine the extent to which reservoir salmonids are using the new habitat for spawning and whether this new habitat is successful in producing young fish that are able to make their way to the reservoir.

Preliminary results from the first two years of the study indicate that a large proportion of the ouananiche population of Meelpaeg Lake is using Compensation Creek for spawning, and that young fish produced in the creek distribute themselves throughout the lake. This indicates that the habitat is functioning as designed.

Exploring vulnerable marine ecosystems (VMEs)

The third key focus of CAHR's work addresses VMEs in Canadian and international waters through DFO's International Governance Strategy. This research addresses issues such as the destruction of seabed habitat due to particular fishing practices and areas that are particularly vulnerable because they have long recovery times from disturbance.

Deep sea corals and sponge reefs, for example, can have recovery times of more than 100 years because they grow very slowly. Growth rate and recovery times are measures of resilience – and many corals aren't very resilient. In contrast, fast growing habitat-defining species such as eelgrass can often recover from disturbance within five years.

"It's abundantly clear that not all areas of the seabed are created equal. Some fish species, including some commercial species, are much higher in abundance around corals and sponge reefs than anywhere else along the continental shelf," says Dr. Gregory. "We're just beginning to discover which areas are very good producers of fish, invertebrates and marine life in general." This knowledge will enable CAHR to provide science advice on fishing impacts and the ecological importance of marine habitats.

Bill Brodie, Dr. Kent Gilkinson and Dr. Ellen Kenchington are developing maps that combine the distribution of fishing effort with the distribution of coral and other vulnerable areas of the seabed. These maps will be used to explore the degree of vulnerability certain habitats have related to specific fishing practices. "We're also looking at how to mitigate the effects of certain types of fishing gear on vulnerable habitats. That may involve something as simple as avoidance," says Dr. Gregory. Advice is also provided on science considerations for the development of Environmental Plans (EP).

Tool development and testing

The centre is also developing and testing tools and methodologies to aid in aquatic habitat research. "Those include ‘tools' in the conventional sense, but also analytical ‘tools' such as better statisical and modeling methods," says Dr. Gregory.

For example, Dr. Vladimir Kostylev of Natural Resources Canada is leading research, in collaboration with DFO, to refine techniques for mapping the sensitivity of benthic (bottom) habitat to disturbance. His team will test the applicability of sensitivity mapping techniques to help guide specific management issues of the Gully Marine Protected Area (MPA). The goal is to provide a better decision support tool to assist with management and regulatory review and compliance of the MPA as well as other Canadian and international spatial management issues.