- Pressure from all sides
- > Marine wilderness that is untouched by humans is almost a thing of the past. Be it underneath the Antarctic ice shelves or in remote deep-sea trenches, traces of human activity can be found everywhere, in the form of noise, plastic particles or rising water temperatures. What makes this so fatal is that humanity’s demands on ocean resources are increasing while the number of stressors threatening marine life is rising in tandem.
An unprecedented downward spiral
Disruptions and damage at all levels
Just like us humans, marine organisms need a safe natural resource base on which they can draw for their growth and healthy reproduction. This primarily includes an intact, unpolluted habitat, ambient temperatures within their specific comfort zone, and sufficient food. However, none of these cornerstones of marine life are considered to be secure today. The direct and indirect interventions of human societies in the global ocean are too far-reaching and severe.
The most important direct drivers of the decline in marine biodiversity are the extraction of raw materials and organisms, changes in the use of coastal areas and oceans, climate change and its consequences for marine life, coastal and marine pollution, and the migration or introduction of invasive species. Indirect impacts are caused by factors such as human population growth, demographic shifts (e.g. urbanization and migration) and socio-cultural, economic, technological and political developments. These factors influence the decisions we make as societies, which ultimately affect nature and marine life. The overexploitation of marine ecosystems in European waters began as early as the Middle Ages, driven by the growing commercialization of goods, raw materials and marine ecosystem services. This continued in other marine regions of the world in colonial times. The present development trajectory can be termed as the industrialization of marine resource use and exploitation. Its extent has increased rapidly since the 1950s, resulting in the damage, destruction or disappearance of many original marine ecosystems and a decline in the population numbers of particular animal populations by more than half since 1970. The loss of marine species diversity is now so severe that a global mass extinction can no longer be categorically ruled out.
It is also a fact that our demands on the sea and its biological communities continue to increase, despite all the species and habitat losses in the ocean. New or drastically intensifying forms of utilization include energy generation at sea, shipping traffic, and fish farming and algae cultivation in aquaculture installations. Meanwhile, marine pollution by waste, microplastics and other pollutants is also mounting.
The consequences of climate change for marine life are a significant source of uncertainty. Not only are they driving thousands of species to leave their traditional ranges, tearing apart food webs and bringing biological processes to a standstill, they are also weakening the health and resilience of many marine organisms. Weakened or stressed organisms usually lack the energy to withstand further disturbances, so the consequences of climate change exacerbate the damage caused by other stressors. Experts speak of a cascade effect, which occurs when several disturbance factors impact in the same place at the same time, reinforcing each other’s effects.
However, there is one piece of good news: selected marine organisms and biological communities in some marine regions are now being systematically monitored, with their condition being regularly assessed by means of a number of different biodiversity indicators. This enables experts to determine whether or not measures to reduce human-induced pressures are effective and whether or not marine life may slowly be recovering.