What are invasive species? Are they always bad for our ecosystems?

Discover how the University is researching the possible benefits – and not just the negative impact – non-indigenous species can bring to new environments
Close-up view of a common lionfish (Pterois miles) courtesy of Shutterstock, Copyright: Henner Damke

What are invasive species?

An invasive or non-indigenous species is an organism that typically causes ecological or economic harm in a new environment where it is not native. 

A few examples of invasive species are green crab, killer algae, sea walnut, lionfish and Pacific oysters.

How are they causing problems?

Invasive species are non-native species that have colonised a new area to the point of damaging the surrounding environment and are seen as one of the top five major threats to our ecosystem today.

They can be brought into a new environment from pathways such as ships, fishing equipment or accidental releases. This is worrying for us as invasive species can damage the services the ecosystems provide us with.

Invasive species are capable of causing extinctions of native plants and animals, reducing biodiversity, competing with native organisms for limited resources, and altering habitats.

Invasive species can have impacts on our marine industries, such as growing on marine structures, killing or competing with marine aquaculture species and by spreading disease.

According to Department for Environment, Food and Rural Affairs (DEFRA) tackling invasive species cost the UK roughly 1.8 billion pounds per year globally. The cost could be over 100 billion per year exceeding the cost of all natural disasters.

How can we manage invasive species?

The UK is taking action to improve the way invasive species are tackled. This is done through the prioritisation of the most harmful species and preventing invasions before they cause irreversible damage by cutting off pathways.

It's thought that costs can be reduced by hundreds to thousands of times with this new preventative approach, in turn protecting our economy and the stability of our valuable ecosystems.

At the University, researchers from the Marine Conservation Research Group based in our Marine Biology and Ecology Research Centre are studying ways to help prevent various evasive species from causing further damage to marine ecosystems. 

One of these is RELIONMED, an on-going EU LIFE project involving Professor Jason Hall-Spencer, Dr Siân Rees and Periklis Kleitou, who are researching ways to deal with a lionfish invasion in the Mediterranean.

However, they are also investigating how some invasive species could also be appreciated for their potential benefits – such as fishery-related tourism, enhanced ecosystem services and food production – and propose a perspective that links fisheries management with conservation and investment strategies.

 

Taming the lionfish

Rising sea temperatures in the Mediterranean are encouraging alien lionfish species to invade and colonise new territories with potentially serious ecological and socioeconomic impacts.

Lionfish are generalist carnivores and can feed on a variety of fish and crustaceans. They spawn every four days, year-round, producing around two million buoyant gelatinous eggs per year, which can ride the ocean currents and cover large distances for about a month before they settle.

Their success at invading new territories stems from a combination of factors such as early maturation and reproduction, and venomous spines that deter predators, and they can quickly colonise reefs and reduce biodiversity in the area.

Evidence collated from divers and fishermen reveals that in the space of a year, the venomous predators have colonised Cyprus – and these may be at the vanguard of a pan-Atlantic Ocean invasion following the widening and deepening of the Suez Canal.

In 2015, a 35km long section of the Suez Canal was deepened and expanded from 61 to 312m wide. This doubled shipping capacity and decreased transit time, but led to urgent calls for improved canal biosecurity in 2016. 

Within just four years, lionfish from the Red Sea have become established over far too wide an area for eradication to be feasible.

The RELIONMED project

RELIONMED is a four-year project (2017-2021), funded by €1,676,077 from the European Union’s LIFE programme, seeking to stem the lionfish invasion in the Mediterranean Sea. 

Working with the University of Cyprus, Jason and his team are helping to coordinate different activities, including the development and implementation of an early surveillance and detection system, and a removal response strategy.

Jason, Principal Investigator for Plymouth said:

“The lionfish is the most ecologically harmful species in the Atlantic. Our aim is to make Cyprus the first line of defence against the invasion in the Mediterranean. It is vital that we help the region to develop the necessary capacity and mechanisms to do this otherwise the spread will continue, risking a range of ecological and economic impacts for Mediterranean countries.”

Siân said: 

“If we can make this a sustainable practice, and one that can easily be replicated in other countries, then we will stand a better chance of slowing or halting the spread of this most harmful of invasive species.”

Can invasive species bring benefits?

A recent research study (November 2020) from Jason, Siân and Periklis now suggests that non-indigenous species need to also be appreciated for their potential benefits and not just the negative impacts they can cause.

There have been numerous examples of non-indigenous species establishing a foothold and then causing harm in new environments, but others have had benefits for fisheries or replaced lost ecological functions.

Stopping the spread of such species is virtually impossible, so a new study – led by the University and the Marine and Environmental Research (MER) Lab in Cyprus – is calling for a complete rethink of how they are considered in the future.

Focused on the Mediterranean, the research highlights species – including lionfish, clams, barracuda, rabbitfish and jellyfish – that have become resident in the region as a result of factors such as the changing climate or human introduction.

A lionfish (Pterois miles) entangled in a fishing net off the coast of Cyprus. All images on this page courtesy of Marine and Environmental Research Lab
A lionfish entangled in a fishing net off the coast of Cyprus

Time for a rethink?

The study, Fishery reforms for the management of non-indigenous species, proposes a cost-benefit analysis which will guide whether non-indigenous species should be managed in a sustainable or unsustainable way.

Where non-indigenous species are known to have positive effects on the environment and marine economies, a series of policy reforms are proposed.

However, where there are no perceived benefits, it proposes legislation to actively promote commercial over-fishing and the creation of radical non-indigenous species-specific licences for recreational fishers, which will help to meet one of the United Nations Sustainable Development Goals.

The study also recommends:

  • investment in the market and valorisation of non-indigenous species products
  • development of novel products and fishery-related tourism
  • the importance of investing in natural-based solutions such as the protection of native predators
  • the enhancement of marine protected areas (MPAs)
  • allowing SCUBA divers to remove invasive species from MPAs.

“What we are proposing is a new governance perspective that firmly links fisheries management with conservation and investment strategies. This research is set to change how non-indigenous species are managed in the Mediterranean and provide long term benefit for society.”

– Siân Rees

Find out more about the recent research in Cyprus

Discover more about the RELIONMED project

Public engagement in Mediterranean lionfish control efforts

Drawing on experiences from the western Atlantic invasion, the study An underwater clash of spears: Public engagement in Mediterranean lionfish control efforts, demonstrates the efficiency of long-term coordinated removals for the first time in the Mediterranean Sea.
The findings revealed a sustained participation and interest throughout the coordinated removal events that encouraged the organisation of future events. 
Removal Action Teams were found effective at reducing lionfish numbers in small (less than half a hectare) areas of high conservation value, when removals were repeated systematically.
Single-day lionfish derbies, operated at greater spatial scales, succeeded in a 50% reduction in lionfish abundance while removing most large (>30 cm) individuals from an area after three consecutive events.

Given the recreational character of such activities, coordinated removals are useful options for management and conservation when guided by competent authorities and supported by citizens, as they promote marine environmental awareness and help develop a sense of stewardship among members of the public.

Eat the Alien

Watch this video about eating marine invasive species to control their populations, featuring two Greek comedians in a restaurant. 
This is part of Professor Jason Hall-Spencer’s ‘Eat the Alien’ project led by iSea in Greece.
 

The Marine Biology and Ecology Research Centre (MBERC)

Members of the MBERC address a broad range of research questions, from the effects of environmental stress on microbes and developing embryos to the management of large scale impacts, such as global climate change.

Find out more about our research
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Marine biology courses at Plymouth

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BSc (Hons) Marine Biology
Anemone. Getty Images

BSc (Hons) Marine Biology and Coastal Ecology
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BSc (Hons) Marine Biology and Oceanography