Justification
The Trichonida Spined Loach is endemic to the lower Achelous River system in southwestern Greece. It has a restricted range (extent of occurrence (EOO) c. 2,563 km2), which meets the threshold for the Endangered category under Criterion B1 (EOO < 5,000 km2). The extent and quality of habitat are estimated to be declining due to habitat modification, pollution and water abstraction, but the number of locations is unknown and it is unclear whether the extant subpopulations are severely fragmented. There is no evidence that this species demonstrates extreme fluctuations. No explicit area of occupancy (AOO), population size or trend data are available and the probability of extinction has not been quantified, so the remaining criteria are presently inapplicable. Therefore, this species is assessed as Near Threatened because it is close to qualifying for Endangered under Criterion B.
Geographic Range Information
This species is endemic to the lower Achelous (el. Αχελώος) River system in southwestern Greece, including Lakes Trichonida (el. Τριχωνίδα), Lysimachia (el. Λυσιμαχία), Ozeros (el. Οζερός) and Amvrakia (el. Αμβρακία). It may also be present in the adjacent Evinos (el. Εύηνος) river system.
Population Information
This species' current population size and trend have not been quantified, and the number of subpopulations is unknown.
The results of recent field surveys are suggestive of declining abundance in lakes Trichonida and Lysimachia, plus the lower Achelous River downstream of the Stratos hydroelectric dam (S. Zogaris pers. comm.).
Habitat and Ecology Information
This small, benthic species primarily inhabits lentic environments such as lake shorelines and marshes, but also occurs in streams and artificial channels with still to moderately-flowing clear water and sand or silty substrata, sometimes with aquatic vegetation.
Like other Cobitis species, it feeds by filtering mouthfuls of fine material through the gills, from which minute organic particles and small benthic organisms are extracted and consumed. It is also a facultative air-breather that makes use of its hindgut as an accessory air-breathing organ.
Little is known of its life history, but related species tend to spawn among submerged vegetation, where the eggs are retained until they hatch.
Threats Information
This species is threatened by habitat modification, pollution, water abstraction, and introduction of non-native fish species.
In particular, the lower Achelous River is intensively exploited for irrigated agriculture, and this has led to overexploitation of local aquifers and the modification of wetlands for drainage and flood control purposes. Pollution due to runoff of nutrients, herbicides and pesticides from agriculture has driven eutrophication and a reduction in the extent of suitable habitat. Soil and river bank erosion has led to an increase in siltation which can negatively impact aquatic vegetation and this species' preferred spawning sites.
Lakes Trichonida, Lysimachia and Ozeros were all once oligotrophic, but their trophic levels are increasing due to human activities. Lake Trichonida is the least affected, but eutrophication is ongoing due to discharge of organic pollution from local agriculture, olive oil producers and livestock facilities, plus untreated domestic wastewater from nearby villages. In addition, a number of sites around the lake are used for illegal dumping of solid waste.
Lake Lysimachia has been classified as eutrophic for decades, having received untreated domestic wastewater from the city of Agrinio until the year 2000. Although this no longer occurs (see 'Conservation'), the lake retains high concentrations of phosphorous and other nutrients, and runoff from agricultural land is ongoing.
Lake Ozeros is undergoing a transition towards eutrophication driven by an increased phosphorous load, which has been attributed to runoff from surrounding agriculture and livestock facilities.
The surface area of Lake Amvrakia has been significantly reduced due to a combination of drought and drainage of the northern portion of the basin. There is a degree of pollution due to pesticide runoff from surrounding agriculture, but this appears to have reduced since the mid-2000s.
Water is also pumped directly from all four lakes to surrounding irrigated land and, in combination with the projected decrease in rainfall linked to climate change, there is a danger that the extent of shorelines inhabited by the Trichonida Spined Loach could be reduced. This species is also threatened by land reclamation for agricultural use in the riparian zone of the lakes.
A series of hydroelectric dams have been constructed on the Achelous River since the 1960s, and these have adversely affected downstream flow regimes, siltation rates and habitat quality for benthic fishes throughout much of the river's main stem.
A partially-completed dam and water transfer system, designed to divert up to 1.5 billion m3 of water annually eastwards from the Achelous to supplement irrigated agriculture on the Thessalian Plain, has been on hold since 2010 following a series of environmental and legal challenges. Within this scheme, a dam at Mesochora in the upper Achelous was completed in 2001, and could soon be made operational according to reports published in 2021.
A number of non-native fish species have been introduced and become established within the range of the Trichonida Spined Loach. These include Topmouth Gudgeon (Pseudorasbora parva), Eastern Mosquitofish (Gambusia holbrooki), Prussian Carp (Carassius gibelio) and Common Carp (Cyprinus domestic strain), all of which are documented to exert negative impacts on native freshwater fauna.
Use and Trade Information
This species is not used or traded.
Conservation Actions Information
This species is listed in Appendix III of the Bern Convention and Annex II of the European Habitats Directive.
No species-specific management scheme is in place, but it occurs within the boundaries of several protected areas. In particular, the Achelous River delta and all four of the lakes to which it is native are included within the European Union's Natura 2000 network (sites GR2310001, GR2310008, GR2310009 and GR2310016). It is included as a target species at three of these sites, but detailed management plans have not yet been completed for any of them. Measures to prevent the discharge of untreated domestic wastewater at Lake Lysimachia have however driven an improvement in water quality since their implementation in 2000.
Research investigating this species' distribution, population trend, life history and response to the identified threats is recommended in order to determine whether direct conservation actions are required.
