Tadpole Shrimps – A General Review of the Little Known Crustaceans of Ephemeral Waterbodies

Abstract

In time of global climate changes, astatic inland water reservoirs that contribute to water retention and alleviation of adverse effects of periodic river floods, are getting more and more important. Small, periodically drying off water reservoirs are also rich hubs of biodiversity. Animals especially connected to such ecosystems are primitive but unique crustaceans called tadpole shrimps (order Notostraca). Those animals seem to have universal significance – both ecological and economic. Though their primitive morphology and small size, they can radically affect the nature of their habitats, sometimes even helping us fight with noxious pests. Unfortunately, due to progressing global warming, intensification in agriculture, and urbanisation, habitats of notostracans are disappearing rapidly. Simultaneously, because of their rare occurences and taxonomic difficulties, tadpole shrimps have been insufficiently studied. However, protection of these crustaceans is inseparably connected with conservation of once numerous, periodically drying reservoirs as tadpole shrimps are referred as keystone species of such habitats. Thus, the aim of this review article is to sum up and disseminate current state of knowledge about Notostraca by a general overview of available international literature. This might help to engage more scientists into research and conservation of these little known, yet interesting crustaceans and their unique habitats.

The use of 18S rRNA for identification of the first record of Tadpole Shrimp Lepidurus apus (Linnaeus, 1758) from Jordan

“…This article identifies the presence of the tadpole shrimp, Lepidurus apus, for the first time in Jordan by sequencing the DNA barcode using the 18S rRNA Gene-Based PCR Assay and comparing the results with other relevant genetic markers to assess genetic distinctiveness. The genetic analysis was helpful in accurately defining the species, especially with the high morphological variability of tadpole shrimp, which makes it challenging to identify the species level (Rogacki and Brysiewicz 2021). By examining the distribution of haplotypes and identifying the positions of mutations, researchers can gain a deeper understanding of how these species have diverged over time and adapted to their respective environments.…”

“…The tadpole shrimps contain two genera: Triops and Lepidurus (Rogers et al 2019). These genera share similar ecologic niches and habitats but never co-occur (Rogacki and Brysiewicz 2021). The individuals from the two genera demonstrate different preferences related to ambient temperature, where cold water in early spring encourages Lepidurus species, and Triops species require warmer water in the spring and summer seasons.…”

“…Lepidurus has a supra-anal plate, distinguishing it from other Triops species (Sorek et al 2016). As a species that lives in temporary water pools that dry up within weeks, it has developed a unique adaptation to survive by producing "resting eggs," or cysts, that reside in the top layers of temporary water body sediments and can withstand droughts, physical damage, lack of oxygen, extreme temperatures, UV radiation, and even survive passage through the digestive system of predators (Rogacki and Brysiewicz 2021). The eggs will hatch in batches under favorable conditions (Savojardo et al 2019) and can be spread passively by several means, such as animals, wind, and floods (Sorek et al 2016).…”

Coastal Treasures of the Eastern Solway: a Species on the Edge project

“…Similar to the natterjack toad, it too has adapted to breed in ephemeral waters, albeit those that occur within a slightly different hydroperiod from those typically preferred by the natterjack toad. Unlike the natterjack toad, however, tadpole shrimp eggs are able to enter a state of diapause that can last in excess of 25 years, during which they are able to withstand freezing temperatures and prolonged periods of drought while awaiting the optimum conditions for development (Rogacki & Brysiewicz, 2021). The species was thought to have become extinct from the Solway during the middle of the 20th century.…”