Fairy shrimps of Andalusia (Crustaceans: Branchiopods)
“Ghost” species locally common: an opportunity to discover this mythical group of crustaceans.
The branchiopods: arthropods, that is, invertebrates with exoskeletons, whose abdominal legs serve as gills, and are mostly restricted to continental aquatic environments. Likewise, they make up the most primitive class of the large group of crustaceans, who are especially diverse and abundant in the sea while insects are so on the continents.
“Surprising” is possibly the best word to define the branchiopods, an animal group whose natural history is often an exception and “breaks the rules”. Of course, they attract the attention because of their scarcity, but also for the curiosity of species which seem to survive against common sense.
The group is divided into four orders. A few macroscopic species are much rare but easy to notice in the field and informally coined as the Large Branchiopods. They include the tadpole shrimps, or notostaceans (literally “shell-swimmer”), represented by the genus Triops of really primitive aspect, the clam shrimps, or concostraceans (“crustaceans-clam”) with protective bivalve shell, and the most diverse and defenseless fairy shrimps, or anostaceans (“without-shell”). To complete this picture, add the broader order of water fleas, or cladocerans (“spiny branch”), which are microscopic and highly modified planktonic organisms within the class, are also bivalves and provided with a terminal spine.
Along with amphibians and various atypical ferns (Marsilea, Isoetes), the Large Branchiopods are the true specialists of temporary Mediterranean ponds and lagoons. This habitat, more abundant in arid regions, is highly threatened by changes in land use and currently considered a priority for conservation.
With 15 detected species, Andalusia represents a diversity hotspot for the group in Europe. The Andalusian Fairy Schrimp (Linderiella baetica) is the rarest and most threatened species by far, known from a single peri-urban locality and developing under specific hydrological conditions of low mineralization. Other notable species are the Iberian Clam shrimp (Cyzicus grubei), the Moorish Clam shrimp (Maghrebestheria maroccana), the aggregate of Mediterranean Triops species (Triops mauritanicus aggr.) and the Iberian Fairy Shrimp (Branchippus cortesi). We must also mention the Brine shrimps (Artemia spp) well known to the public and restricted to salt flats and salty lagoons.
Spectacular Mediterranean tadpole shrimp (Triops mauritanicus agg.).
We have been passionate about Mediterranean temporary pools and have carried out multiple inventories of large branchiopods in Andalusia.
Dynamics in temporary pools
A miniature ecosystem where to observe an ecological succession developing on a scale of days. This extraordinary dynamism and the effect of chance turn the wetlands in Andalusia into exciting environments for the nature observer.
Puddle Fairy schrimp (Branchipus schaefferi): .
How long can the eggs last in the substrate? What is the preference of the species depending on the depth of the water column and salinity? How many species can live in the same pond? How do these apex species colonize new bodies of water, by air and by land? Why is there especially bright coloration on the abdomen of females?
Stage 1: After prolonged rains throughout the fall and winter, the endorheic terrestrial depressions, that is, those that do not flow into streams, are saturated with water. Depending on the size of the drainage basin, ponds and even lagoons are formed on otherwise barren land, mostly characterized by sparse terrestrial vegetation, and where the seed bank of plants and branchiopod eggs goes unnoticed.
Stage 2: These habitats are little more than masses of low mineralized water, which cools overnight, and are devoid of vegetation. After a few days, the eggs hatch and the first branchiopods massively colonize the pond, feeding on algae and organic debris. Finally, the first winged insects and amphibians colonize the ponds in order to start a reproductive cycle.
Stage 3: Very variable period, depending on factors such as the volume of the water body, the physical-chemical conditions and the precipitation regime of the year. As for large branchiopods, typical deep-water and saline species develop later in season. For other species, mature females have allready layed eggs that settle to the bottom and require a drying period to hatch. In shallow ponds, the water becomes warmer, without getting so cold at night. A veritable explosion of life fills the ponds with organisms: aquatic plants have grown very vigorously, a new generation of predatory insect larvae and tadpoles have become abundant, and aquatic birds frequently visit wetlands to feed. In particular, the ardeidae (storks, egrets or herons) take advantage of abundant food of amphibians and perhaps Triops. Meanwhile, large branchiopods are increasingly scarce, being predated or not supporting maximum water temperatures.
Stage 4: The pond has passed its peak and is beginning to dry out very noticeably. The branchiopods are already very scarce, although isolated individuals achieve a considerable size. Aquatic insects and amphibians have metamorphosed in great numbers, plants have completed their life cycle. New rains could bring back the previous stage, but the end of a season is already noticeable.
Stage 5: the pond is dry, although at first humidity favors dense herbaceous vegetation, at least in non-salty soils. Quickly, the aridity gains ground and the surfaqce becomes barren again concealing its riches … until the next rains.
Large branchiopods: List of species present in Andalusia
Identification of adults
|Anostraca||Artemiidae||Artemia franciscana||San Francisco Brine shrimp||Tricky||Exotic||Hipersaline||Scarce|
|Artemiidae||Artemia parthenogenetica diploide||Diploid Brine shrimp||Tricky||Paleartic||Hipersaline||Rare|
|Artemiidae||Artemia parthenogenetica tetraploide||Tetraploid Brine shrimp||Tricky||Paleartic||Hipersaline||Rare|
|Artemiidae||Artemia salina||Brine shrimp||Tricky||Paleartic||Hipersaline||Rare|
|Branchipodidae||Branchipus cortesi||Iberian Fairy Shrimp||Easy||Iberian||Shallow Ponds||Scarce|
|Branchipodidae||Branchipus schaefferi||Puddle Fairy Schrimp||Easy||Paleartic||Shallow Ponds||Common|
|Branchipodidae||Tanymastix stagnalis||Marsh Fairy Shrimp||Unmistakable||Western Paleartic
|Chirocephalidae||Branchinectella media||Mediterranean Fairy Schrimp||Tricky||Mediterranean, Central Asia
|Chirocephalidae||Chirocephalus diaphanus||Diaphanous Fairy Schrimp||Easy||Paleartic||Shallow Ponds||Most Common
|Linderiellidae||Linderiella baetica||Andalusian Fairy Schrimp||Tricky||One pond in Cadix||Shallow Ponds|| Very Rare (CR)
|Streptocephalidae||Streptocephalus torvicornis||Tweezers Fairy Schrimp||Unmistakable||Paleartic||Deep ponds||Rare|
|Thamnocephalidae||Phallocryptus spinosa||Spiny Fairy Shrimp||Easy||Circummediterránea||Hipersaline||Rare|
|Notostraca||Triopidae||Triops mauritanicus aggr.||Mediterranean tadpole shrimp agg.||Unmistakable/ Dificult||Ibero-maghrebian||Shallow Ponds||Common|
|Spinicaudata||Cyzidae||Cyzicus grubei||Iberian Clam shrimp||Tricky||Ibero-balear||Shallow Ponds||Rare|
|Leptestheriidae||Maghrebestheria maroccana||Moorish Clam shrimp||Tricky||Ibero-maghrebian||Shallow Ponds||Very Rare|
1: Publicación de referencia:
IUCN: Riesgo de extinción, teniendo en cuenta los Libros Rojos de Andalucía (criterios regionales de la UICN), España (criterios nacionales de la UICN) y la Lista Roja UICN (análisis global). LR: Lower Risk. NT: Near Threathened. VU: Vulnerable. EN: Endangered. EX: Extinct.