Banner Photo Credit and Description: Neil Fisher; Pacific prawn, Pandalus platyceros
Monitoring provides valuable knowledge on success and progress at a given location and can inform techniques and methods for future projects. Developing effective long-term monitoring and management strategies is therefore an investment in current and future project costs. Monitoring plans should be devised before project construction occurs, have project specific goals and questions to be addressed, and be developed with an appropriate assessment of available resources and capacity. Where possible, the requirements of post-construction monitoring should be considered in developing the baseline data collection program required as part of the AR site selection, design criteria development and environmental permitting processes (Section 3).
Monitoring plans for restoration projects can be grouped into three broad categories: research-level investigations conducted by scientists who have the expertise, time, and resources needed to address in-depth estimations of habitat restoration efficacy or performance of innovative design concepts; simple audit or compliance surveys conducted by experts who can assess project impacts on fish productivity, habitat/ecosystem function, and structural performance; and those that fall in between these two extremes. The last category is where restoration monitoring plans tend to fall short of their goals, and fail to provide adequate data that can be used in comparing project impacts. Trying to do too much with limited resources can result in unusable or ambiguous data. Collecting simple and repeatable metrics can produce reliable predictions of environmental health and allow for project performance assessment over time.
Finally, monitoring plans should extend beyond the project boundaries to include the area of influence of the project. Monitoring plans designed to achieve an in-depth analysis of project impacts should involve thorough data collection, such as fish and invertebrate use of the restored habitat, long-term measurement of the relevant physical parameters (see Section 2), and interpretation of the project’s effects and successes.
Shore Zone Monitoring Considerations
Shore zone habitat monitoring consists of assessing site and project stability, changes in physical properties, vegetation coverage, and habitat use by target species at the compensation and reference sites. This should occur annually for approximately five years, and use transects and quadrats to record species coverage. After this amount of time most shore zone ecosystems will generally reach a stable biological composition and equilibrium. Some monitoring parameters and indicators include: water quality; seagrass distribution, cover, and density; sediment deposition and/or erosion rates; changes to the site morphology; species at risk; fish and invertebrate abundance, behaviour, and distribution; forage fish community composition, spawning distribution, and biomass; changes in community composition; and habitat destruction by fishing, anchoring, dumping, construction, or other development actions.
Monitoring efforts need to specify a purpose in order to determine the overall cost and direction of monitoring efforts. Some goals include:
- To ensure habitat provides ecosystem function and services that mitigate or compensate for habitat lost through development activity
- To demonstrate habitat use by specific species
- To demonstrate habitat structure obtains similar composition and productivity levels to pre development region and surrounding natural habitats
- To confirm a lack of adverse impacts on area of influence for the project
- To assess and monitor the structural integrity of the project
For example, if demonstrating that fish are using the restored habitat is a project goal, fish sampling should be included in the monitoring plan. This will significantly increase the cost of project monitoring and therefore must be accounted for in the project objectives stage of project delivery.
Artificial Reef Monitoring Considerations
AR design needs to be coupled with an appropriate management strategy that considers ownership, liability, regulation, user conflict, environmental assessment, and long-term management needs. It also needs to assess and regulate harvesting pressure and account for physical processes that affect species abundance and distribution and community succession patterns, including the effects of climate cycles such as ENSO and long-term climate change. Improper management can lead to over-exploitation of limited stocks that concentrate around the AR, especially if this concentration is mistaken for increased productivity.
It is important to understand that since ecosystem recruitment and succession take place over decades, monitoring programs must understand and work within this time-frame. In order to ensure permanent effectiveness of the AR, long-term monitoring of reef integrity and function need to be guaranteed either by the development company or a contracted group. Current monitoring patterns in California fall into four year monitoring procedures for community colonization and structure. In Washington state monitoring is mandated to occur quarterly for two years after construction.
Long-term monitoring and pre-construction surveys must integrate diel and seasonal fish movement into assessment efforts in order to obtain accurate results. Seasonal and ontogenic population fluctuations may skew monitoring results unless they are properly understood and accounted for. Other recommended indicators of success include: benthic fish species composition, abundance, and diversity; macro-invertebrate species composition, abundance, and diversity; macro-algae species composition, abundance, and diversity; and the age and size structure of rockfish and lingcod.
Survey techniques include visual censuses (diving), still and video photography, fishing surveys, acoustics, tagging, and telemetry. Surveys should monitor for: reef use classification (horizontal and vertical use), length of occupancy, fidelity to reef, life cycle stage that uses the reef, and the behavioural response to the reef. A striking challenge to formulating management plans for ARs is determining how to measure productivity. One method for assessing productivity changes is quantifying the total regional catch or standing stock in some proportion to the amount of AR material deposited, while accounting for fishing effort, recruitment from surrounding areas, and changes in year class strength.
Another example of quantifying habitat productivity using an ecosystem approach involves selecting indicators from varying trophic levels. For example, quantifying the biomass of algae, invertebrates, fish, and riparian vegetation gives a more comprehensive picture of how habitat alterations affect ecosystem productivity than using one surrogate species. Quigley and Harper (2006) suggest that indicators from lower trophic levels, such as invertebrates and algae, are less variable than higher trophic level indicators and thus better represent gross differences in habitat productivity.
It is imperative to ensure that management coordination occurs with fisheries managers, and to understand how fishing activity in the reef vicinity influences an AR’s success. Reef fish are particularly easy to exploit since they have a low mobility, slow growth rates and concentrated populations. A key component regarding the interaction of fisheries and AR success involves educating local fisheries about the reef purpose and presence in order to decrease illegal fishing activity.
- Ensure that an integrated management approach is used for shore zone project design, construction and management. Understand the interactions between physical parameters and ecological functions and services of the habitat under consideration. In addition, pre-impact baseline data must be collected that includes species assemblage, temporal and spatial abundance and distribution, species’ habitat use and requirements, physical and oceanographic data, human influences, and overall ecosystem productivity for the target ecosystems. This information is vital in assessing whether the restored habitat succeeds at achieving minimal HADD to habitat and NL of habitat productivity.
- Ensure that shore zone projects are designed with a long-term focus that considers the dynamic nature of physical and biological processes on structural integrity and function. In coastal system, this includes the effects of physical processes, such as winds, waves, storm events, and coastal flooding on habitat integrity and species assemblage.
- Ensure that construction occurs at an appropriate time relative to species abundance and vulnerability.For example, construction should not coincide with periods of spawning (varies per species) or peak biomass (summer). In addition, habitats should be constructed before peak colonization occurs (often the spring), since this influences community structure through primary colonization and succession. Construction should also be initiated before development activity occurs in order to diminish temporal losses of habitat productivity that occurs as a result of the time lag between habitat disruption or destruction, compensation development, and compensation functionality.
- Understand that project design criteria and habitat designs are not extensible to other regions or sites due to inherently local ecosystem and physical processes