To sum up, I will be researching the abundance and potential impacts of microplastics on a species of sea cucumber found in Antarctica. This is important for several reason: Firstly, Antarctica has been known to be a pristine environment. Unfortunately, this is no longer the case due to plastic pollution and anthropogenic impacts. Secondly, this specific species of sea cucumber stops eating for several months at a time. This means that the microplastics that have been ingested can leach harmful toxins and potential cause blockages and other serious health issues. The money raised will be used for the research and my supporting costs.
The production of plastic has increased significantly, with an annual production of 336 million tonnes in 2016. Up to 12.7 million metric tons of this plastic waste was shown to be entering the marine environment, suggesting that plastic pollution is a problem on a global scale. Microplastics can be defined as particles less than 5mm in diameter, although there is currently no agreed standard size, and have been shown to make up the majority of plastic pollution within the marine environment. Litter, discards, wind inputs, river inputs and accidental release can all lead to plastic ocean pollution.
Microplastics can originate from either primary or secondary sources. Primary microplastics are manufactured to be under 5mm in size for use in cosmetics and toothpastes. Microplastic fibres can originate from clothing and fishing nets. Secondary microplastics originate from macroplastics, of which can be degraded and worn down by physical, biological and chemical processes. UV-induced photooxidation and physical weathering by wave action can cause the breakdown of macroplastics and production of secondary microplastics.
Due to the increasing quantities and residence times of microplastics, chances of ingestion are increasing and it is important to consider the effects of this on marine life. Persistent organic pollutants and heavy metals use plastics as a transport vector. This includes bisphenols, phthalate plasticisers and polybrominated diphenyl ether flame retardants. Microplastics themselves can release toxic monomers and plasticizers, used for increased durability and antifouling, can leach into the environment or organism. Due to the large surface area to volume ratio of microplastics, high quantities of these pollutants are adsorbed with evidence of hepatic stress being directly linked to this. The ingestion of microplastics can also lead to entanglement within the intestinal tract, blockages, increased in gut-retention time, reduction in reproduction, drowning and even death.
There have been many studies worldwide into the distribution of microplastics. However, there is less research into the presence of microplastics in the Southern Ocean. Antarctica is thought to be a pristine environment and isolated from external stressors and pollutants due to its unique oceanography, often described as ‘The Last Ocean’. Antarctica is highly seasonal with low primary production in the winter, and much higher primary production in the summer. This is due to the expansive pack ice cover in winter causing a reduction in light. Ice will melt during the austral summer, releasing microbiota of which sinks to benthic communities.
Recent studies have highlighted the presence of macroplastic and microplastics in surface and pelagic waters, as well as within the sediments of the Southern Ocean. The Southern Ocean is a cold environment with specifically adapted organisms and ecosystems. The trophic transfer of microplastics can pose a threat to these species, with potential long-term impacts such as the blockage of digestive tracts, internal abrasion and suppressed feeding.
Antarctic organisms are well adapted to extreme conditions. One example of this is the echinoderm, Heterocucumis steineni, of which is found throughout the Southern Ocean. This species is usually found at depths of 20 to 30m and suspension feeds on particles found in the water column. Echinoderms in the Southern Ocean have the ability to reproduce and grow in periods where food availability and light levels are low. During austral winter, Heterocucumis steineni ceases feeding for a period of up to 6 months and will frequently retreat in order to avoid predation. There is evidence of benthic holothurians ingesting microplastic with a significant preference shown towards microplastic fibres, with up to 517 microplastic fibres found per individual. Fibres are more likely to sink and be present within benthic communities. This is of interest as, if Heterocucumis steineni ingest microplastics prior to the austral winter in which ingestion ceases, there is an opportunity for these particles to remain within the digestive tract for up to 6 months. This provides more of an opportunity for microplastics to pose a threat to these organisms due to leaching of toxins, entanglement and a wide range of other complications.
The objective of this research is to identify any temporal patterns in the abundance and potential source of microplastics found within Heteocucumis steineni. It is hypothesised that there will be a greater abundance of microplastics found within species collected during the austral winter, due to the potential retention of particles when feeding ceases. It is also hypothesised that there will be a higher abundance of microplastic fibres over other microplastics. such as fragments and beads. A British Antarctic Survey data set, dating back to 1998, will be used in order to make comparisons between summer and winter periods as well as comparisons between potential years of interest.