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Marine defaunation: Animal loss in the global ocean

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Science  16 Jan 2015:
Vol. 347, Issue 6219, 1255641
DOI: 10.1126/science.1255641
  • Timeline (log scale) of marine and terrestrial defaunation.

    The marine defaunation experience is much less advanced, even though humans have been harvesting ocean wildlife for thousands of years. The recent industrialization of this harvest, however, initiated an era of intense marine wildlife declines. If left unmanaged, we predict that marine habitat alteration, along with climate change (colored bar: IPCC warming), will exacerbate marine defaunation.

  • Fig. 1 Comparative chronology of human-associated terrestrial and marine animal extinctions.

    Green bars indicate animal extinctions that occurred on land, and blue bars indicate marine animal extinctions. Timeline measures years before 2014 CE. Only extinctions occurring less than 55,000 years ago are depicted. Defaunation has ancient origins on land but has intensified only within the last several hundred years in the oceans. See details in (8).

  • Fig. 2 Marine defaunation threat.

    Threat from defaunation is portrayed for different groups of marine fauna as chronicled by the IUCN Red List (113). Threat categories include “extinct” (orange), “endangered” (red; IUCN categories “critically endangered” + “endangered”), “data deficient” (light gray), and “unreviewed” (dark gray). Groups that contact land during some portion of their life history (green) are distinguished from species that do not (light blue). The total number of species estimated in each group is listed below the graph. Species groupings are coded as follows: ST, sea turtles; PO, pinnipeds and marine mustelids; SS, seabirds and shorebirds; SSL, sea snakes and marine lizard; CS, cetaceans and sirenians; DBRF, diadromous/brackish ray-finned fishes; CF, cartilaginous fishes; MRF, exclusively marine ray-finned fishes; MI, marine invertebrates. See further details in (8).

  • Fig. 3 Comparisons of range contractions for select marine and terrestrial fauna.

    Terrestrial (green) and marine cases (blue) include evaluations of geographical range change for: 43 North American mammals over the last ~200 years (NM) (114), 18 Indian mammals over the last 30 years (IM) (115), 201 British birds from ~1970 to 1997 (BB) and 58 British butterflies from ~1976 to 1997 (BF) (116), 12 global large pelagic fishes from the 1960s to 2000s (PF) (14), and 327 trawl-surveyed North American marine fish and invertebrates from the 1970s to 2000s (TFI). (A) Percent of species whose ranges have contracted with binomial confidence intervals and (B) distribution of percent contraction for those species that have contracted (violin plot). Sample sizes are shown above each data point, white horizontal lines (B) show the medians, and thick vertical black lines display the interquartile range. See details in (8).

  • Fig. 4 Mobility of terrestrial and marine fauna.

    Because mobility shapes defaunation risk, we compare the size-standardized home range size of a representative selection of marine (blue) and terrestrial (green) vertebrates. Data are presented for adults over a full range of animal body sizes, plotted on a logarithmic scale. Species include seabirds, marine reptiles, marine fishes, marine mammals, terrestrial birds, terrestrial reptiles, and terrestrial mammals (see details in (8); table S2 and fig. S3). Regression lines enclosed by shaded confidence intervals are plotted for all marine and all terrestrial species. The dotted red line demarcates the current median size of all marine protected areas (MPAs).

  • Fig. 5 Habitat change in the global oceans.

    Trends in six indicators of marine habitat modification suggest that habitat change may become an increasingly important threat to marine wildlife: (A) change in global percent cover of coral reef outside of marine protected areas [percent change at each time point measured relative to percent coral cover in 1988 (44)]; (B) global change in mangrove area (percent change each year measured relative to mangrove area in 1980) (117); (C) change in the cumulative number of marine wind turbines installed worldwide (118); (D) change in the cumulative area of seabed under contract for mineral extraction in international waters (119); (E) trends in the volume of global container port traffic (120); and (F) change in the cumulative number of oxygen depleted marine “dead zones.” See details and data sources in (8).

Additional Files

  • Marine defaunation: Animal loss in the global ocean

    Douglas J. McCauley, Malin L. Pinsky, Stephen R. Palumbi, James A. Estes, Francis H. Joyce, Robert R. Warner

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Materials and Methods
    • Figs. S1 to S7
    • Tables S1 and S2
    • References

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