Restoring coastal lagoons for the conservation of a critically endangered freshwater fish
Valencia toothcarp or samaruc (Valencia hispanica) is a small freshwater fish, endemic to Eastern Iberian coastal wetlands. It is restricted to a few small areas in Catalonia and Valencia, and is on the verge of extinction because of the degradation of its habitat and because of competition with Eastern mosquitofish (Gambusia holbrooki), a highly-competitive invasive fish.
Less than 15 wild populations remain, and they are geographically isolated. Captive breeding projects are being carried out but protection of its habitat is inadequate.
This threatened species needs clean, lowland springs and does not tolerate high salinity levels. These springs have suffered intense degradation because of pollution, destruction and the introduction of non-native species.
Currently, the coastal lagoons at L’Ametlla de Mar (Baix Ebre) are a refuge for this species. These lagoons are exceptionally well preserved, and they lack problematic invasive fish. In the area there are also populations of fartet (Aphanius iberus), another endemic Iberian toothcarp, which is also threatened.
Coastal lagoons are considered habitats of priority interest by the European Union (*1150 Coastal Lagoons).
Coastal lagoons provide many valuable ecological functions, such as the buffering of sea–storms.
Many European coastal lagoons have either disappeared or are degraded. In this area, several shallow lagoons are found, populated by aquatic macrophytes such as stoneworts (Chara hispida) and fennel pondweed (Potamogeton pectinatus), and sorrounded by sedges, reeds, and a rich dune vegetation. The lagoons have both a groundwater origin and a marine influence, and are located in the mouth of Mediterranean ramblas (temporary streams).
In this area, some coastal lagoons had disappeared due sediment loading. With the funding of Andrena, the organization Paisatges Vius planned the restoration of three previously existing lagoons, with the aim of recovering habitat for the samaruc.
Specific hydrogeological studies have guided all the works, in order to guarantee the natural hydrology of the lagoons. Their environmental status is monitored using QAELS e2010 , an index of water quality assessment in Mediterranean wetlands based on crustacean and insect assemblages, and ECELS, an indicator for the general conservation status of the ecosystem, based on morphological aspects.
In order to establish new populations, captive-bred samarucs have been reintroduced in these lagoons, after an ecosystem assessment. Fishes were introduced during the mating and breeding season (late Spring).
The lagoons are surveyed twice a year by Ebro Delta Natural Park biologist. Surveys have shown that samaruc is breeding well in the newly restored lagoons, and the new populations are thriving.
- L’Estany Tort Restoration of the original lagoon, which had disappeared during the 70s. Introduction of samarucs from the breeding facilities at the Icthyological Centre in the Delta de l’Ebre Natural Park.
- Llacuna del Port de l’Estany Restoration of the lagoon, formerly disappeared due to sediment loading and disconnected from the sea by a road. Introduction of captive-bred samarucs.
- Llacuna de Torrent del Pi Restoration of two more ponds in this network, increasing habitat size. Samarucs have colonized naturally this lagoon.
- Llacuna de Cala Justell Restoration of a coastal lagoon. Introduction of captive-bred samarucs.
- Ichtyological Centre – Delta de L’Ebre Natural Park Equipment and materials have been provided to support their toothcarp captive breeding program.