Human‐induced marine ecological degradation: micropaleontological perspectives

Abstract

We analyzed published downcore microfossil records from 150 studies and reinterpreted them from an ecological degradation perspective to address the following critical but still imperfectly answered questions: (1) How is the timing of human-induced degradation of marine ecosystems different among regions? (2) What are the dominant causes of human-induced marine ecological degradation? (3) How can we better document natural variability and thereby avoid the problem of shifting baselines of comparison as degradation progresses over time? The results indicated that: (1) ecological degradation in marine systems began significantly earlier in Europe and North America (∼1800s) compared with Asia (post-1900) due to earlier industrialization in European and North American countries, (2) ecological degradation accelerated globally in the late 20th century due to post-World War II economic growth, (3) recovery from the degraded state in late 20th century following various restoration efforts and environmental regulations occurred only in limited localities. Although complex in detail, typical signs of ecological degradation were diversity decline, dramatic changes in total abundance, decrease in benthic and/or sensitive species, and increase in planktic, resistant, toxic, and/or introduced species. The predominant cause of degradation detected in these microfossil records was nutrient enrichment and the resulting symptoms of eutrophication, including hypoxia. Other causes also played considerable roles in some areas, including severe metal pollution around mining sites, water acidification by acidic wastewater, and salinity changes from construction of causeways, dikes, and channels, deforestation, and land clearance. Microfossils enable reconstruction of the ecological history of the past 102–103 years or even more, and, in conjunction with statistical modeling approaches using independent proxy records of climate and human-induced environmental changes, future research will enable workers to better address Shifting Baseline Syndrome and separate anthropogenic impacts from background natural variability.

Ecological selectivity of the emerging mass extinction in the oceans

“…Rather, human fishing and hunting define the dominant threat to modern marine fauna (2,19,20). Although we observed no contemporary association between threat and habitat zone in these taxa, others have documented preferential and widespread modern declines in benthic marine microfauna resulting from nutrient pollution and oxygen deprivation in bottom waters (21). The sustained proliferation of dead zones associated with nutrient pollution (22) Fig.…”

Is the meiofauna a good indicator for climate change and anthropogenic impacts?

“…Ostracods respond to pollution-induced environmental changes showing high sensitivity to heavy-metal pollution, oil discharges and anoxic conditions (Ruiz et al 2005). Some ostracod species are adapted to hypoxic conditions and can dominate in polluted environments (Alvarez Zarikian et al 2000;Yasuhara et al 2012b). In addition to changes in the Ostracoda community, morphological and geochemical changes can also be detected in ostracod shells (Ruiz et al 2005).…”

Biology in the Anthropocene: Challenges and insights from young fossil records

“…118). Diatoms and other proxy records show that estuarine and lacustrine ecosystems have become more plankton-rich and detritus-based in recent decades to centuries, depending on the timing of watershed development and/or removal of key consumers, even when systems had been naturally eutrophic and episodically hypoxic over previous millennia (123)(124)(125).…”