High diversity of Ruppia meadows in saline ponds and lakes of the western Mediterranean

Abstract

Saline inland and coastal waterbodies are valuable habitats that deserve attention for the protection of their unique submerged macrophyte beds that render the water clear, stabilize sediments and provide a habitat for high biomasses of invertebrates as food for waterfowl. The 'continental seagrass' Ruppia has the widest salinity tolerance among the submerged macrophytes and occurs in a wide variety of saline saltmarsh pond and lagoon systems. Although two cosmopolitan species Ruppia maritima and Ruppia cirrhosa are recognized in Europe and Ruppia drepanensis in the western Mediterranean, their diversity and distribution are not well known. This previously held traditional idea that there are only two widespread Ruppia species suggests a uniform and very homogenized population structure following the hypothesis of long-distancedispersal through strong bird-mediated dispersal events. Therefore, the Ruppia chloroplast DNA diversity was investigated along a more than 1,000 km transect of the Iberian Peninsula. We studied 492 individuals from 11 wetland areas (17 ponds) and sequenced a 1,753-bp length of seven chloroplast introns. Eight haplotypes represented at least four distinct groups or taxa which is higher than commonly accepted. Six wetland areas contained more than one haplotype and within-pond diversity occurred within distances as small as 30 m (5 out of 17 cases). This underlines the importance of single waterbodies for harbouring haplotypic diversity in Ruppia. Unique haplotypes were observed in four wetland areas and R. maritima was detected only from a low salinity pond, suggesting the species might be more rare than previously accepted. The present results tend to minimize an overall effect of strong bird-mediated dispersal. This emphasizes the role of regional pond habitat diversity for the preservation of Ruppia taxa and their unique haplotype diversity in extreme saline habitats.

Differences in the growth cycle ofRuppia cirrhosa(Petagna) Grande in a Mediterranean shallow system

“…In temporarily flooded areas, the growth cycle of Ruppia plants is completed before the lagoon dries up, and that led to the interruption of growth and then to the death of these plants; instead, in permanently flooded areas, plants maintained their vegetative structures throughout the year, although maximum development takes place in summer (Verhoeven 1979;Brock 1982;Gesti 2000;Malea et al 2004;Gesti et al 2005). In the Mediterranean region, three species, Ruppia maritima L., Ruppia cirrhosa (Petagna) Grande and Ruppia drepanensis Tineo (considered by Zhao & Wu 2008 as synonyms of R. cirrhosa), are now recognized, the last species occurring only in the south-western Mediterranean (Comín et al 1993;Triest & Sierens 2009.…”

Lagoons and saltwater wetlands getting more diversity: A molecular approach reveals cryptic lineages of a euryhaline submerged macrophyte (Ruppia)

“…Chloroplast haplotype diversity of Ruppia at population level throughout Europe showed five different haplotype groups, with haplotype A corresponding to R. drepanensis Tineo, a species endemic to the SW Mediterranean region; haplotype groups A, B and C belong to a R. cirrhosa (Petagna) Grande species complex; haplotype D is identified as unique to R. maritima populations. Combined with nuclear ITS marker identity, an ancient hybrid, identified as haplotype E, was added to this R. cirrhosa species complex (Triest & Sierens, , , , ), and confirmed at regional level in lagoons of S.W. Europe (Martinez‐Garrido et al, ).…”

“…Chloroplast haplotype diversity of Ruppia at population level throughout Europe indicated four different haplotype groups (see Methods section). Combined with nuclear ITS marker identity, an ancient hybrid (named haplotype E in Triest & Sierens, , ), was added to this R. cirrhosa species complex; this is in addition to more recent hybrid formation across Europe (Triest & Sierens, , , , ), and subsequently confirmed at the regional level in lagoons of SW Europe (Martinez‐Garrido et al, ). Ito et al (, ) circumscribes this as a single R. maritima complex, despite maternal cpDNA referring to R. cirrhosa relationship and despite ample populations of independent studies (Martinez‐Garrido et al, ; Triest & Sierens, ; Yu et al, ) confirming the separation of R. cirrhosa as a distinct gene pool at nuclear DNA level.…”

“…This is further thwarted because of phenotypic plasticity that can be found within the genus (Mannino, Menendez, Obrador, Sfriso, & Triest, ). The number of Ruppia species and their distribution are largely unknown (Short, Carruthers, Dennison, & Waycott, ) thereby leading to misunderstandings of species identity (den Hartog & Kuo, ) and their conservation status (Triest & Sierens, ). Because of the monospecific beds, these species and their unique environmental relationships are most relevant for habitat prioritization at lagoon level.…”

Pond conservation: from science to practice

“…In the Landscape Protected Areas (LPA) of southern Estonia, the creation of several hundred ponds for the management of amphibian populations demonstrates how effectively conservation measures can be put in place (Rannap et al, 2009). The significance of conserving biodiversity at the regional scale was also demonstrated by Triest and Sierens (2009) who emphasize the role of regional pond habitat diversity for the preservation of Ruppia taxa and their unique haplotype diversity in extreme saline habitats. Ponds also provide a stepping stone for freshwater biodiversity linked to larger waterbodies providing a resting place for birds and mammals (e.g.…”