Biodiversity... Or Not?

Steffen et al. (2015) assert that biosphere integrity has exceeded its planetary boundary. Unfortunately, as per usual, humans are the most likely culprits here. We are involved in a number processes that lead to a reduction in biodiversity, to name a few:

Plastic dumping

• Ingestion of plastics has led to a decline in particular Mediterranean species:
  o   54 less Loggerhead Mediterranean turtles (Bugoni et al. 2001)
  o   171 less Mediterranean birds across 9 species (Codina-García et al. 2013)

• Entanglement
  o   Possible 10,000 Fur Seals on Bird Island, Georgia had suffered from entanglement, which would’ve caused restricted movement and thus possible death from starvation. (Croxall et al. 1990)
  o   62 Gannet Birds in Grassholm, Wales entangled each year (Votier et al 2011)

• Absorption of pollutants
  o   Plastics can also be carriers of pollutants such as Polychlorinated Biphenyls (PCBs). Evidence of PCBs have been found in Great Shearwater birds and may have a damaging effect on them
  
  

Pollution from industrial chemical dumping

• Oil and Petroleum is very harmful to marine life and can greatly reduce biodiversity. The Gulf of Mexico British Petroleum oil spill had several impacts on various species (Biological diversity report, 2011):
  o   82,000 birds of 102 species injured or dead
  o   6,165 sea turtles injured or dead
  o   25,900 marine mammals injured or dead
• A rare species of Iguana on a Galapagos Island fell from 25,000 to 10,000 after a coastal oil spill (Revkin 2002)

What does this mean for us? Well, firstly it means less interesting wild marine life to see. It also means less marine animals available for us to consume and should we consume unhealthy marine animals, it may also have health impacts on us. As more marine species populations go into decline, there are less marine creature for other marine life to feed on, which may lead to starvation and trophic crash. As we can see from this Steffen et al. graph below, marine fish capture is already beginning to decline, which begs the question: have we already reached the peak?

The Living Planet Index shows a 39% decline in marine species between 1970 and 2010. Eutrophication, an increase in nutrients in an environment, can lead to the death of zooplankton, fish and shellfish due to their sensitivity to oxygen; this can then lead to trophic crash and a regime shift to an alternative stable state (WHO, 2002).

Due to these issues, there has been a rise in the demand for marine management and aquaculture (aquatic farming). Here, Schröder shows how the aquaculture market has grown over the past 30 years:

Steffen et al. also demonstrates how shrimp aquaculture along has seen a shocking level of growth over the same time period:

As more marine life becomes endangered, there has been increased investment in protecting marine habitats and species. An ever-increasing human population and an arguably declining marine population has led to a rise in demand and a fall in supply for aquatic organisms. This has led to exponential growth of the aquaculture market, as seen above, which is expected to reach over $195 billion by 2019 (Marine Water, Freshwater and Brackish Water, 2013).