Human pressures

We gathered data on 14 different human activities and via expert opinion and discussion assessed the extent and strength of the pressures caused by said activities. Though eutrophication and climate change have a strong impact on the Bothnian bay, when analyzing human pressures in SEAmBOTH we chose to focus on local human pressures as they are easier to mitigate. The data was gathered from a wide variety of sources: orthophotos, HELCOM, Finnish Transport Infrastructure Agency, Swedish National Land Survey, Swedish Maritime Administration, Vahti (Compliense monitoring system), and EMODnet.

The map of human pressures digitized from the aerial photos. Map Metsähallitus.

The 14 human activities were:

• Bridges

• Coastal defense and flood protection

• Deposition of dredged material

• Dredging

• Finfish mariculture

• Harbours

• Jetties (brygga/ laituri)

• Land claim (excluding harbours, oil terminals)

• Marinas and leisure harbours

• Recreational boating and sports

• Shipping density

• Wind farms (operational)

• Anchorage sites

• Fishing effort (all gear types)

Each human activity was assessed regarding two separate effects on the marine nature: physical loss of nature values and disturbance to nature values. Here loss is defined as areas were either a total or partial destruction of nature values has occurred due to direct physical action, such as a site that has just been dredged. Disturbance is defined as areas where nature values have been affected and are under pressure from human activities but are not necessarily physically destroyed or removed, such as areas near and around dredging sites.

We created separate spatial layers for both loss and disturbance, estimating the areas affected. A so-called weight table which estimates how strongly the different pressures affect nature values was also created. By combining the weight values with the spatial layers we were able to create maps that estimate the extent and intensity of human pressures in the SEAmBOTH area.

This map is an aggregate (sum) of all weighted loss layers. (Map by Marco Nurmi, SYKE)
This map in turn is an aggregate of all weighted disturbance layers. (Map by Marco Nurmi, SYKE)
Here both maps shown above (i.e. the aggregated loss and disturbance maps) have been aggregated into a single map showing the total effects. (Map by Marco Nurmi, SYKE)

Results show that a large part of the shoreline has been affected by human activity to at least some degree in the recent past. A significant contributor to pressure near the coast is dredging. Shipping effects a very large part of the SEAmBOTH area, though the effects are more diffuse than most activities and the activity is mostly relegated to deep areas. The analysis indicates that areas near Oulu, Kemi, Haparanda, and Karlsborg are most affected by human activities. As stated previously, eutrophication and climate change were not considered in the human pressure analysis.

Unfortunately, both human activities and nature values tend to accumulate at the same area; near the shoreline. Fortunately, steps can be taken to reduce the impact our activities have so that we can ensure a healthy marine nature for the future.

Marco Nurmi, SYKE

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