Social and economic drivers affecting marine food webs
The global demand for food and energy has risen and continues to rise, resulting in intensive exploitation of marine resources and the use of the sea for the production of renewable energy. In addition to intensive fishing and the renewable energy infrastructures, accelerated climate change including atmospheric warming and changes in precipitation is projected for this region during the 21st century. Mitigating climate change increases the need for renewable energy. Furthermore, adaptation to climate change potentially drives changes in marine life by changing the seascape to provide for flood protection. Additionally, globalization and increased consumerism resulting in shipping and pollution are other important driving forces in this region as these activities influence the different trophic levels of the food web.
All social and economic drivers have the potential to influence the quality status of complex food webs.
With the world population projected to grow from 7,3 billion to approximately 9,7 billion by 2050, as consumption per capita increases and available natural resources decrease (Powlson et al., 2010), research suggests that 40% more protein from the sea will be needed by 2030. Fishing is a direct response to society’s need for food. Current policies focus on fishing at sustainable levels to protect fish stocks; however, some practices lead to adverse impacts on the marine ecosystem, and this requires management.
In addition, the growing population increases society’s need for energy. The introduction of infrastructure associated with renewable and non-renewable energy to the marine environment has the potential to either directly or indirectly affect marine life. An example of such direct impact is the localised temperature changes associated with power station outputs. Water used as a coolant may alter the distribution and abundance of organisms at different trophic levels, including food sources. Energy security activities, such as modifications to water courses or effects from renewable energy installations, might also drive impacts on marine organisms. Moreover, hydrological changes (stratification and mixing regime) from wind farms can impact both benthic and pelagic habitats and diversity in different trophic guilds.
The marine food webs leading to seafood species are among the many goods and services generated by marine ecosystems. Their utilisation has been a characteristic of human societies since the earliest times. Threats to all marine species in the food web drive public pressure for political debate and action, because of society’s needs and its appreciation of nature and biodiversity. Pelagic and benthic species play critical functional roles in biogeochemical processes. They are particularly important in secondary production, both as a direct food source (e.g. clams) and as major food sources for pelagic and bottom-feeding species that are commercially fished.
The multiple factors driving activities that can create climate change impacts include the burning of fossil fuels, industrialised farming practices and deforestation, and these also drive impacts on fish. Society’s need to mitigate the effects of climate change has led to the expansion of renewable energy technologies. The introduction of the associated infrastructure to the marine environment can either directly affect benthic trophic guilds or directly or indirectly affect fish species. In addition, coastal and flood protection, sea defences, levees and dikes are being increasingly introduced, driven by society’s need to adapt to the effects of climate change. Again, such infrastructure has the potential to either directly or indirectly affect fish species and their habitats.
The production of goods and services helps to meet society’s need for stable economies. The manufacturing and processing of goods can introduce pollutants to the marine environment which can affect lower, upper and apex trophic guilds, either directly or indirectly.
Society’s need to manufacture and process goods drives their trade and movement, their shipment by sea, and navigational dredging in support of shipping. However, each can contribute to the input or remobilisation of contaminants in the marine environment. Vessel movements may disturb fish and marine mammals.
Population demands for goods requiring manufacturing and processing, and for services such as waste treatment and disposal, are on the increase. These are driven by society’s need for health and wellbeing. However, these activities can introduce pollutants (including plastics) to the marine environment that can become concentrated in marine resources. Plastic litter is now one of the most serious threats to the marine environment. Over 690 marine species have been impacted by plastic debris, with small plastic particles being observed in the digestive tracts of organisms from all different trophic levels. Growing populations are increasing the demand for housing and utilities, and therefore increasing society’s need for materials and their processing. The manufacturing and processing of goods can introduce pollutants to the marine environment. Activities such as mineral extraction and infrastructure installation lead to the restructuring of seabed morphology, which can drive impacts on benthic and fish habitats.