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Indicator name 

Cumulative Human Impacts on Marine Ecosystems

What does this data layer represent? 

This indicator measures the amount of pressure anthropogenic drivers have on marine ecosystems. There are two datasets representing the Cumulative Human Impacts on Marine Ecosystems on the Dashboard. The first dataset illustrates the most recently available conditions in 2013, which measures the impact of 19 global anthropogenic stressors on 20 different ecosystem types. The second dataset portrays the change in Cumulative Human Impacts on Marine Ecosystems between 2008 and 2013. Only 12 anthropogenic stressors were used to develop the 2008 dataset, so the same 12 stressors were considered to develop a "subset" version of the 2013 dataset to provide a consistent comparison. The Change in Cumulative Human Impacts on Marine Ecosystems represents the difference between these 2008 and 2013 (subset) datasets.

What does a trend in this indicator tell us? 

The Cumulative Human Impacts on Marine Ecosystems indicator values calculated within national exclusive economic zone (EEZ) boundaries range from 0-4.35, with higher values representing greater anthropogenic impacts on marine ecosystems. The average change in Cumulative Human Impacts on Marine Ecosystems within the EEZ boundaries ranges from -0.62 - 1.72, with higher values representing faster rates of increase in anthropogenic impacts on marine ecosystems. Negative change values represent decreasing anthropogenic impacts on marine ecosystems (i.e., improving conditions for marine biodiversity). Although the Cumulative Human Impacts on Marine Ecosystems dataset spans all areas of the ocean, the indicator as delineated on the Dashboard focuses on national exclusive economic zones (EEZs), where most human uses of the ocean are concentrated and where national policies can have the greatest influence on altering the magnitude of human impacts on marine ecosystems.

NatureServe re-analyzed the source datasets from 2008 and 2013 (subset using 12 anthropogenic stressors) to graph the annual change in the Cumulative Human Impacts on Marine Ecosystems scores to aid spatial visualization of the trends. Since the average values stated above were derived directly from the baseline 2013 dataset and change between 2008-2013 dataset, values on the pop-up line graphs may differ.

How was the indicator developed? 

B. Halpern and colleagues developed this indicator by integrating 12 global datasets of anthropogenic drivers available data the 2008 and 19 global anthropogenic stressors for 2013 (Table 1) on ecological change for 20 marine ecosystems (Table 2) at a 1 km2 resolution (Halpern et al. 2008; Halpern et al. 2015). The anthropogenic stressor datasets were rescaled to range from 0 to 1 and used to derive pressure data by adjusting for habitat pressure and vulnerability. The sum of the pressure data was then calculated to create the cumulative impact datasets for each year the indicator was measured. Of the original 19 anthropogenic stressors used to develop the latest 2013 dataset, a subset of the 12 stressors used to derive the 2008 dataset were used to develop a comparable 2013 human impact dataset. Halpern and colleagues developed the change in the Cumulative Human Impacts on Marine Ecosystems by calculating the difference between the 2008 and 2013 (subset) pressure and cumulative impacts.

Table 1. Anthropogenic stressors included in the datasets used for the 2013 baseline and change between 2008-2013 for the Cumulative Human Impacts on Marine Ecosystems indicator (adapted from Halpern et al. 2015 Supplementary Table 1). 

Type of Stressor

Anthropogenic Stressor

Years used in 2013 dataset

Years used in 2008 dataset

Land-based

Nutrient pollution

2007-2010

2003-2006

Organic pollution

2007-2010

2003-2006

*Inorganic pollution  

2000-2001

Direct human

2011

2006

Light pollution

2007-2010

2004-2006

Fishing

Demersal, destructive

2011

2006

Demersal, non-destructive, high bycatch

2011

2006

Demersal, non-destructive, low bycatch

2011

2006

Pelagic, high bycatch

2011

2006

Pelagic, low bycatch 2011

2006

*Artisanal

2006

 

Climate change

SST anomalies

1985-1990 vs. 2005-2010

1985-1990 vs. 2000-2005

UV radiation 2008-2012

1997-2001

*Ocean acidification 1870 vs. 2000-2009

 

*Sea level rise

1992-2012

 

Ocean-based

*Commercial shipping

2003-2011

 

*Invasive species

2011

 
*Ocean-based pollution

2005

 
Benthic structure

2007-2010

2004-2006

* Stressors only available for the baseline 2013 dataset. These stressors were not used to measure human impacts for the 2008 dataset, and therefore were not used in the subset 2013 dataset compared to the 2008 to calculate change.

Table 2. Marine ecosystems considered in the datasets used for the 2013 baseline and change between 2008-2013 for the Cumulative Human Impacts on Marine Ecosystems indicator (adapted from Halpern et al. 2015 Supplementary Table 1).

Type of Ecosystem

Marine Ecosystem

Year assessed

Intertidal

Rocky intertidal

Modeled

Beach

Modeled

Mud flats

Modeled

Salt marsh

Modeled

Mangroves

2006

Coastal (<60m depth)

Seagrass beds

2006

Shellfish reefs

Modeled

Coral reefs

2006

Rocky reefs

2005

Kelp forests

Modeled

Shallow soft bottom

2005

Offshore (>60m depth)

Continental shelf, hard bottom (60-200m)

2005

Continental shelf, soft bottom (60-200m)

2005

Continental slope, hard bottom (200-2000m)

2005

Continental slope, soft bottom (200-2000m)

2005

Deep benthic, hard bottom (>2000m)

2005

Deep benthic, soft bottom (>2000m)

2005

Shallow pelagic (<60m)

2013

Deep pelagic (>60m)

2013

Seamounts

2004

Limitations and caveats 

While the Cumulative Human Impacts on Marine Ecosystems global analysis measures change in anthropogenic stressors, the results do not account for possible habitat loss. The analysis also assumes that the responses of natural systems to human stressors are linear and additive, whereas marine ecosystems might display threshold responses to high levels of overlapping stressors. The potential unaccounted habitat loss and non-linear responses to anthropogenic stressors may have contributed to the results underestimating the changes in anthropogenic impacts on marine ecosystems.

Although the analysis calculated the overall change in anthropogenic stressors on marine ecosystems between the years 2008 and 2013, the raw stressor datasets slightly varied from these years. This may have resulted in measurements differing slightly from the strict 2008 and 2013 base years.

Where can I get more information about this indicator? 

More information and further resources are available in the indicator factsheet here.

Data sources 

National Center for Ecological Analysis and Synthesis (NCEAS)

References 

Halpern, B. S., Walbridge, S., Selkoe, K. A., Kappel, C. V, Micheli, F., D'Agrosa, C., Bruno, J.F., Casey, K.S., Ebert, C., Fox, H.E., Fujita, R., Heinemann, D., Lenihan, H.S., Madin, E.M.P., Perry, M.T., Selig, E.R., Spalding, M., Steneck, R., Watson, R. (2008). A Global Map of Human Impact on Marine Ecosystems. Science, 319: 948-952.

Halpern, B. S., Frazier, M., Potapenko, J., Casey, K. S., Koenig, K., Longo, C., Lowndes, J.S., Rockwood, R.C., Selig, E.R., Selkoe, K.A., Walbridge, S. (2015). Spatial and temporal changes in cumulative human impacts on the world's ocean. Nature Communications, 6(7615), 1-7.