Algae - Data Information

Methodology

Essentially, the project sought to create an Internet platform that could be used to display the distribution of various marine seaweed species and allow resource managers and users from the research field and the industry to consult the data. The historical data sets were obtained by consulting publications and the archives of researchers. For the more recent data, researchers and their graduate students as well as the organisations that have conducted macroalgae surveys were contacted directly and they kindly shared their data (Table 1).

Table 1. List of sources and data providers and characteristics of the main datasets.

Data provider Data type Species Year(s) Site(s) Reference
Dr Mathieu Cusson (UQAC) Coverage % All 2010-2013 North Shore, Sainte-Flavie  
Dr Ladd Johnson (ULaval) Biomass Laminariales 2012-2013 Mingan Islands  
AMIK Density, biomass Fucales 2011-2012 North Shore Report
Louise Gendron (MAPAQ) Density, biomass Laminariales 1981 Chaleurs Bay Report
André Cardinal Presence All 1960-1971 St. Lawrence Estuary and Gulf Reports and published artices
Marcelle Gauvreau Presence All 1934-1939 St. Lawrence Estuary and Gulf Thesis and report
Divers Presence Laminariales, Fucales 2010-2013 St. Lawrence Estuary and Gulf Survey

The data obtained from archives or articles published prior to 2000 were entered manually into Excel files while the more recent data were obtained already in this format from each of the suppliers. The data were then standardised and compiled in two large files: a qualitative file in which the species lists were assembled (presence) and a quantitative file compiling all the abundance data (density, biomass, coverage %, etc.) and when available, the associated parameters (substrate, fauna). These data are now disseminated in the Biodiversity application of SLGO, however some of the quantitative data is not available directly in this application but may be accessible by contacting Éric Tamigneaux from Merinov.

Sampling

As for field data collection, for most of the studies consulted, the brown seaweed abundance data were obtained by transect and quadrat sampling (Béland, 2012, Hurd and colleagues, 2014; Côté-Laurin and Tamigneaux, 2016). In the case of mediolittoral-level seaweed beds, measurement was done by operators walking along the tidal flats at low tide; in contrast, for the survey work on brown seaweed beds in the continually submerged infralittoral level, the quadrats were sampled by scuba divers.

Results

For the two major seaweed groups and the 8 species indicated in Table 2 above, the data base contains nearly 3,000 elements and covers an area from Île d'Orléans to Anticosti Island and the Magdalen Islands. Of these, 2,660 elements come from quadrats with quantitative abundance values for several species as well as information on the substrate and community associated with the seaweed population.

An examination of the data base reveals, first of all, that the floristic surveys conducted in the 1930s and 1960s by Marcelle Gauvreau and André Cardinal thoroughly covered Québec's various coastal zones (north and south shores of the maritime estuary, Middle North Shore, the Gaspé Peninsula and the Magdalen Islands) (Merzouk, 2016). In contrast, there is less information for the 1980s, 1990s and 2000s and there are gaps. Moreover, it was not possible to find data for the shores of Anticosti Island or for the north shore of the Gaspé Peninsula from Matane to Gaspé. In general, except for the thorough surveys conducted by AMIK in the area between Les Escoumins and Sept-Îles in 2012, there is no recent information on seaweed bed extent, composition or biomass. To facilitate surveying in Québec, work is currently underway to test seaweed bed cartography methods using airborne optical sensors or acoustical sounders (see Publications section: Perrot 2015; Grant and colleagues, 2015).

Several of the zones surveyed on the Gaspé Peninsula, on the North Shore and in the Lower St. Lawrence show that the brown seaweed biomasses in those areas compare advantageously to those observed in the maritime provinces and in Europe, and are abundant enough (≥ 2 kg m-2) to support commercial harvest. In the case of knotted wrack, for instance, biomasses of 3.5 to 12 kg m-2 have been reported for the south shore of the St. Lawrence Estuary while biomasses of 1 to 16 kg m-2 have been reported for the north shore of the St. Lawrence Estuary.

In some places, such as at the Mingan Islands, a comparison between recent and historic data shows that kelp bed biomasses and composition have remained stable over time. In contrast, in the Lower St. Lawrence anecdotal information indicates that although rockweed beds are stable, kelp beds are declining or have disappeared at several sites. The data with the highest quality and best spatial coverage are the most recent (post-2010) and they include quantitative data (density and biomass) for Fucales and Laminariales.