‘Dead Shrimp Blues’

I woke up this mornin’ and all my shrimps was dead and gone

So sang the legendary blues artist Robert Johnson back in 1937. Sadly, it’s a lyric which resonates today, according to a study led by the Museum and the International Union for Conservation of Nature (IUCN).

Almost 28% of the world’s 762 freshwater shrimp species, a group which supports the livelihoods of some of the world’s poorest communities, are now threatened with extinction, according to the IUCN Red List of Threatened Species. The main threats include urban and agricultural pollution, human intrusions and disturbance, and invasive species.

“Freshwater shrimps are extensively harvested for human food, especially by the poorest communities in tropical regions, where they often dominate the biomass of streams and play a key role in regulating many ecosystem functions. However, little is known about the impacts the loss of these species may cause to ecosystem services,” say the Museum’s Sammy De Grave, lead author of the report, which is published in the journal PLOS ONE.

Two species were declared as Extinct and a further ten are also Possibly Extinct, but require field surveys to confirm that status. Several of these species are only known from a single cave or stream in locations which have undergone significant levels of habitat degradation and conversion, and have not been sighted for decades. For example, Macrobrachium purpureamanus is only known from peat swamps on Kundur Island, Riau Archipelago (Indonesia), an area which from 1998 has been extensively converted to an oil palm plantation.

The research, which collated distribution data for all species, identified areas containing high levels of species diversity in the Western Ghats, Madagascar, the Guyana Shield area, the upper Amazon, Sulawesi and Indo-China.  Additionally, high concentrations of cave-dwelling species were found in areas of China, the western Balkan Peninsula, the Philippines and Cuba.

Although threatened species are found across the globe, notable concentrations were found in Sulawesi (Indonesia), Cuba, the Philippines and southern China, many of which are restricted to cave habitats. As well as cave-dwelling species, those restricted to lakes and freshwater springs also face higher levels of threat. The Alabama Cave Shrimp (Palaemonias alabamae), for example, is listed as Endangered, and is known from only four cave systems in Alabama, USA that are currently under threat from groundwater abstraction and habitat change.

As well as making a number of recommendations for conservation actions, the report stresses the urgent need for field research to increase understanding of the life histories, threats and distribution of many shrimp species.

“The high levels of extinction threat that the team found for freshwater shrimps have also been found for freshwater crabs and crayfish, and these studies of global faunas highlight the fragile state of freshwater invertebrates across the world,” says Neil Cumberlidge, Chair of the IUCN Species Survival Commission (SSC) Freshwater Crustacean Specialist Group.

“Sadly, the prospect of losing these important species often goes unnoticed. The information on these threatened freshwater crustaceans is readily available on the IUCN Red List and needs to be incorporated into decision making at all levels if we are to protect the world’s rapidly deteriorating freshwater habitats and the amazing but highly threatened species that live there.”

The study, Dead Shrimp Blues: A global assessment of extinction risk in freshwater shrimp (Decapoda: Caridea), involved researchers from the UK, Australia, Austria, Brazil, Indonesia, Mexico, Singapore and Taiwan.

Sammy De Grave – Head of Research