The goal of our project was to identify the location of a new marine protected area through the consideration of a multitude of factors through a multiple criteria evaluation process: the distribution of marine mammals, the distribution of vegetation, the locations of biologically significant areas, bathymetry, and sea surface temperature. The first three factors were used in order to select the location and area of our final marine protected area, while the last two factors were used to create an output of suitable locations from the suitability modeller.
Current marine protected areas in British Columbia focused on a variety of specific goals, such as the preservation of glass sponge reef areas, the protection of habitats surrounding hydrothermal vents, and the conservation of ecosystems surrounding seamounts (Department of Fisheries and Oceans, 2020). Instead, our marine protected area was to target the conservation of habitats that upheld the highest overlapping distribution of marine mammal ranges, as British Columbia has yet to dedicate a marine protected area tailored towards the protection of pinnipeds and cetaceans. Additional consideration was also given to vegetation and biologically significant areas as determined by the Department of Fisheries and Oceans.
As stated in the methodology, we used the ‘Count Overlapping Features’ tool and the ‘Select’ tool in order to determine our proposed marine protected area. Our marine protected area is located on the southern side of Vancouver Island, right along the shore between Carmanah Walbran Provincial Park and Port Renfrew. The perimeter of our marine protected area is 21,668.88 meters, with an area of 17,816,952.45 meters squared. The projected coordinate system of our marine protected area is NAD 1983 BC Environment Albers.
Our marine protected area contains the overlapping habitats of the northern fur seal, harbour seal, harbour porpoise, gray whale, Dallas porpoise, and the California sea lion, all of which are native to British Columbia. The marine protected area also overlaps the ranges of kelp and eelgrass beds, and is located in a region that is deemed biologically significant in general. Furthermore, our MPA also covers the salmon trawling ground. Trawling has caused tremendous disturbance to the marine ecosystem, because bycatch of other unwanted species may occur, especially rare and protected species (Wainwright et al., 2019). If our MPA were established, disturbance to the local ecosystem will be eliminated as all kinds of fishery practices like trawling will be banned within that area.
Afterwards, we wanted to determine whether the location of our marine protected area was reasonable in consideration of key environmental factors. These environmental factors were sea surface temperature and bathymetry, which were also two of the physical features used to examine marine mammal hotspots off the coast of British Columbia in recent literature (Harvey et. al, 2017). More specifically, colder sea surface temperatures, as well as regions of shallow bathymetry, were identified as being most favourable for the increased presence of marine organisms (Harvey et. al, 2017). The sea surface temperature used for this project was computed as the average temperatures from May to August.
Colder sea surface temperatures relative to nearby regions indicate areas of upwelling (Harvey et. al, 2017). Upwelling is a physical process of great importance within the field of oceanography as regions of upwelling yield the greatest rates of primary production (Peterson et. al, 2007). In the summertime, southeasterly winds will drive the warmer water on the sea surface away from the coast. As masses of surface water move off shore, colder and nutrient-rich waters from the deep rise in order to replace this loss, resulting in upwelling. This massive input of nutrients is what leads to increases in primary production of the sea surface, and therefore a higher presence of marine life (Peterson et. al, 2007). In addition, shallower bathymetry, on the other hand, is most favourable for a variety of reasons. Firstly, areas of shallow depths are associated with structures such as banks, seamounts, and continental shelves, which are all important sites of enhanced marine productivity such as zooplankton (Yen et. al, 2004). Prey species are consequently greatly concentrated within these shallow regions, leading to an increase in abundance of predator species as well (Yen et. al, 2004) which includes top predators such as pinnipeds, whales, and dolphins.
For the weightings of both variables, we decided that bathymetry should be weighted heavier than sea surface temperature (see Table 1 for our weights). We decided to include SST (sea surface temperature) and depth as our criteria, and the weightings of SST (63%) is heavier than that of bathymetry (37%). Scientific literature have illustrated that sea depth will have a greater influence than SST. For instance, according to Gagné et al. (2020), bathymetry is more accountable in explaining marine species richness than SST. McHenry et al. (2019) also illustrated that the habitat of a wider range of species depends more on bathymetry than SST. We initially also included rugosity as our third factor, but we later decided to remove it from the MCE (see the Limitations section for further discussion).
In the end, we compared our marine protected area with the top three regions that have the most suitable sea surface temperature and bathymetry for marine species. Our MPA overlaps with the region of the highest suitability. Our MPA also does not overlap with current MPAs.
Most importantly, the fact that it was perfectly situated amongst the areas of suitable locations supports the fact that our MPA was reasonably chosen and located with all of the factors, both biological and physical, having been considered.
One possible benefit of this result is that using a simple method (i.e. overlapping layers to create MPA) can yield desirable results especially if sufficient biological features are taken into consideration, as biological features are often the reflection of suitable environmental factors. As shown, our MPA did overlap regions of the highest suitability. This might indicate that in the future, we can use simple special join methods like overlapping to find areas with the greatest conservation values that already have suitable abiotic conditions.
Continue to our discussion on limitations.