Ponto-Caspian gammarids: Change salinity of the water

Overall effectiveness category Likely to be beneficial
Number of studies: 2
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How is the evidence assessed?

Effectiveness

40%
Certainty

50%
Harms

not assessed

Calculating overall effectiveness category

Background information and definitions

Freshwater gammarid shrimps are sensitive to increased levels of salt in the water. Addition of salt to the water, or exposure to sea water therefore offers a potential management tool.

Study locations

Key messages

One of two replicated laboratory studies (one controlled) in Canada and the UK found that increasing the salinity level of water killed the majority of invasive shrimp within five hours. One found that increased salinity did not kill invasive killer shrimp.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A replicated, controlled laboratory experiment in 2009, on specimens taken from a river in Canada (Ellis & McIsaac 2009) found that invasive freshwater shrimp Echinogammarus ischnus, were killed when salt was added to water. Within five hours, 66% of shrimp died from exposure to saline water (30% salinity). It did not make a difference if the water salinity was increased gradually or immediately. Only 33% of shrimp treated survived for up to two days and 0% beyond two days. Ten shrimp were placed in each of 12 glass jars. The water in four of the jars had 30% salinity from the beginning (using unfiltered river water). The salinity in another four jars was 4% at the start of the experiment and increased every hour to 8, 14, 24 and 30%. Four jars were controls (freshwater only). Every hour for five hours, and after 24 and 48 hours, dead animals were removed and live animals counted.
Study and other actions tested
Referenced paper
Ellis S. & McIsaac H.J. (2009) Salinity tolerance of Great Lakes invaders. Freshwater Biology, 54, 77-89.
A controlled laboratory study conducted in 2011 in England, UK (Stebbing et al. 2011) found that adding salt to freshwater did not kill the killer shrimp Dikerogammarus villosus. None of the shrimp died during the test period. This included shrimp exposed to salinity levels 3.5 times more saline than normal seawater. Tests were conducted on 5 captive shrimp immersed for 15 minutes in de-chlorinated water of different salinities ranging from 5 to 160 grams of salt/litre. Artificial marine salt was used to adjust the salinity in the test solutions. Dead and live shrimp were counted.
Study and other actions tested
Referenced paper
Stebbing P.D., Sebire M. & Lyons B. (2011) Evaluation of a number of treatments to be used as biosecurity measures in controlling the spread of the invasive killer shrimp (Dikerogammarus villosus). CEFAS report, Final contract report C5256, 40pp.

Please cite as:

Aldridge, D., Ockendon, N., Rocha, R., Smith, R.K. & Sutherland, W.J. (2020) Some Aspects of Control of Freshwater Invasive Species. Pages 555-87 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

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This Action forms part of the Action Synopsis:

Control of Freshwater Invasive Species

Related Actions

Actions	Effectiveness	Studies	Category
Ponto-Caspian gammarids: Exchanging ballast water Action Link	No evidence found (no assessment)	0	Synopsis Link
Ponto-Caspian gammarids: Change water pH Action Link	Unlikely to be beneficial	1	Synopsis Link
Ponto-Caspian gammarids: Biological control using predatory fish Action Link	No evidence found (no assessment)	0	Synopsis Link