A symptom of the decline in abundance of species is loss of biodiversityWhat is the definition of biodiversity? When we ask, what is the definition of biodiversity? It depends on what we want to do with it. The term is widely and commonly misused, leading to significant misinterpretation of the importance of how animals function on Earth and why they matter a great deal, to human survival. Here I will try to More [1] which leads to a destabilisation of ecosystemsHow ecosystems function An ecosystem is a community of lifeforms that interact in such an optimal way that how ecosystems function best, is when all components (including humans and other animals) can persist and live alongside each other for the longest time possible. Ecosystems are fuelled by the energy created by plants (primary producers) that convert the Sun's heat energy More [2]. Note, the decline is in the abundance, not the number of species.
!!Species diversity DOES NOT EQUAL biodiversity!!
The capacity of animals to transport nutrientsEnergy and nutrients are the same thing. Plants capture energy from the Sun and store it in chemicals, via the process of photosynthesis. The excess greenery and waste that plants create, contain chemicals that animals can eat, in order to build their own bodies and reproduce. When a chemical is used this way, we call it a nutrient. As we More from biodiversity hotspots and spread them around the world has declined by 92% on land and 96% in the oceans (Bar-On et al 2018) and humanity has wiped out over 60% of the world’s individual fish, mammals, birds, reptiles and amphibians since 1970 (Doughty et al 2015).
The consequence is a reduction in resources and reduced predictability of resources, both of which lead to lowered carrying capacityThe population of animals that a steady-state ecosystem can support. It’s the number that results when total mortality equals total birth-rate. Populations aren’t evenly-distributed to carrying capacity depends on there being both population sources and populations sinks that balance each other out. This is why it can never be said that “animals can move somewhere else”. Loss of critical habitat More [3]. This reduction in predictability is caused by release of free surplus energyThe energy of a system that is emitted as waste and is not part of ecosystem processes. There is always some free surplus energy as this creates the basis for evolution where new species exploit gaps in the ecosystem where free energy becomes available. Surplus energy can occur as a result of disruption or disturbance. When free surplus energy reaches More [4], which upsets the ocean and atmospheric climate, by reintroducing excess heat. This is climate change and it has become the “consumer face” of biodiversity loss.
Loss of biodiversity equally affects animals and primary agriculture (e.g. fisheries and farming) because both depend on the same processes to deliver nutrients at the right time, place and concentration.
But losing animals also creates a snowball effect, because animals simultaneously feed back into the nutrientA substance that contains the raw materials for life. At a chemical level, these are contained inside compounds that are absorbed into the body and essential energy-containing molecules are extracted, so that energy can be transformed into other chemical processes that use the energy for living. More cycles. These feed back cycles are what gave us the biodiversity necessary to stabilise ecosystems and deliver fertile soil and rich oceans, in the first place. Animals give and take, whereas primary agriculture mostly just takes.
Therefore, in order to have viable fisheries and farming, you need abundant animals in the right proportions to stabilise ecosystems. Loss of animals will inevitably hasten to decline in human food security.
References
Bar-On, Y., R. Phillips, and R. Milo, The biomassThe weight of living organisms. Biomass can be measured in relation to the amount of carbon, the dry weight (with all moisture removed) or living weight. In general it can be used to describe the volume of energy that is contained inside systems, as the size of animals relates to their metabolism and therefore, how much energy they contain and More distribution on Earth. Proceedings of the National Academy of Sciences, 2018. 115: p. 201711842.
Doughty, C., et al., Global nutrient transport in a world of giants. Proceedings of the National Academy of Sciences of the United States of America, 2015. 113.
