Finding the boundary between Eurosiberian and Mediterranean salt marshes

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(1)Journal of Coastal Research. SI 56. 1340 - 1344. ICS2009 (Proceedings). Portugal. ISSN 0749-0258. Finding the Boundary between Eurosiberian and Mediterranean Salt Marshes J.C. Costa†, P. Arsénio†, T. Monteiro-Henriques†, C. Neto‡, E. Pereira‡, T. Almeida† and J. Izco∞ † Instituto Superior de Agronomia Technical University of Lisbon (TULisbon) Tapada da Ajuda 1300-049 Lisboa, Portugal jccosta @isa.utl.pt; arseniop@isa.utl.pt; tmh@isa.utl.pt. ‡ Department of Geography University of Lisbon Alameda da Universidade 1600-214 Lisboa, Portugal carlosneto@fl.ul.pt; estevao@fl.ul.pt. ∞ Departamento de Botánica University of Santiago de Compostela Campus de Santiago 15704 Santiago de Compostela, España jesus.izco@usc.es. ABSTRACT COSTA, J.C., ARSÉNIO, P., MONTEIRO-HENRIQUES, T., NETO, C., PEREIRA, E., ALMEIDA T. and IZCO, J., 2009. Finding the Boundary between Eurosiberian and Mediterranean Salt Marshes. Journal of Coastal Research, SI 56 (Proceedings of the 10th International Coastal Symposium), 1340 – 1344. Lisbon, Portugal, ISSN 0749-0258. In continental Portugal it is generally recognized that the Ria de Aveiro is the coastal limit between Mediterranean and Eurosiberian regions. Considering salt marshes flora and vegetation communities, the Tagus River estuary seems typically Mediterranean, while the Ria de Aveiro lagoon seems typically Eurosiberian, therefore the boundary between the two regions might be found among the smaller salty areas existing between the two referred wetlands (namely the Óbidos Lagoon, the Tornada and Mondego rivers). Although tide height is a sound explanation for the floristic differences between Eurosiberian and Mediterranean saltmarshes, the fact is that the southwest Portuguese Atlantic salt marshes present Mediterranean climate and flora, despite its greater tide heights if compared to the Mediterranean Basin. Conversely, Mediterranean climate by its own is not enough to explain those florisitc differences, as it exits north of Aveiro. We introduced the importance of seasurface temperature in order to detail the boundary between the two regions. Despite climate and hydrologic regime being Mediterranean between the Tagus and the Ria de Aveiro, the cold Atlantic waters seem to influence the flora and the vegetation of the present salt marshes. It is proposed to classify as Eurosiberian all salt marshes north of the Tagus Basin. ADDITIONAL INDEX WORDS: Biogeography, Flora, Plant communities, Sea-surface Temperature. INTRODUCTION The frontier between the Mediterranean and the Eurosiberian regions converge to the Portuguese northwest coastline, where Eurosiberian and Mediterranean coastal species come across and migrate between the two regions (IZCO, 1989, 1992). Regarding salt marshes particularly, it is difficult to establish this limit sharply, since an evident physical barrier is lacking. Anyway, the biogeographical coastal terrestrial borderline was established on the Ria de Aveiro by COSTA et al. (1999). Several taxa contributed for that separation, as, for instance, Elytrigia juncea subsp. juncea, Armeria welwitschii, Lotus creticus, Juniperus turbinata, Stauracanthus genistoides, Daucus halophilus, Limonium virgatum, L. multiflorum, L. plurisquamatum, which are typical Mediterranean species that do not appear north of the Ria, or Honkenya peploidis, Jasione lusitanica, Coincya johnstonii, Armeria pubigera, Festuca rubra subsp. pruinosa and Romulea clusiana, which instead are absent below that limit (COSTA, 2001). A number of syntaxa also helped to locate this frontier, among which Juniperion turbinatae, Osyrio quadripartitae-Juniperetum turbinatae, Elytrigietum junceo-boreoatlanticae, Armerio welwitschii-Crucianelletum maritimae, Corynephorion canescentis, Herniario maritimae-Corynephoretum maritime, Herniario robustae-Corynepheretum maritimi, Rubio longifoliaeCorematetum albi, Stauracantho genistoidis-Halimietalia commutati and Stauracantho-Corematetum. These syntaxa are. only encountered south of the Ria, while Euphorbio paraliaeElytrigietum boreoatlanticae, Iberidetum procumbentis, Koelerion arenariae, Jasiono sabulariae-Corynephoretum maritimi, Cisto salviifolii-Ulicetum humilis are typical Cantabrian-Atlantic communities (COSTA et al., 1999; COSTA et al., 2000; NETO et al., 2008; LOMBA et al., 2008). Salt marsh physiognomy differs among tropical, mediterranean and temperate climates. In the tropics, arboreal vegetation (Raunkiaer phanerophytes) is dominant leading to communities known as mangroves; in Mediterranean and desert tropical territories shrubs dominate (vegetation types are essentially nanophanerophytes, microphanerophytes, accompanied by chamaephytes and hemicryptophytes); in temperate climates vegetation is generally short, such as rushlands or halophytic grasslands (hemicryptophytes dominate, along with a few chamaephytes) (COSTA, 2001). Halophytic communities only establish themselves where the coast is protected from the direct action of waves and maritime currents and if fresh water influence, sediments deposition and gentle slopes exist, thus occurring merely in estuaries and quiet bays (CHAPMAN 1960, RANWELL, 1972). Vegetation plays a fundamental role in the sedimentation process, on one hand providing vegetal debris, which is transported by tide flows, on the other hand, holding the same debris and consequently creating a dense felt which slows down water and retains suspended sediments (TEIXEIRA and ALVIM, 1978).. Journal of Coastal Research, Special Issue 56, 2009 1340.

(2) Finding the Boundary between Eurosiberian and Mediterranean Salt Marshes. «anova.cca()» were used respectively for Jaccard distance calculation, constrained correspondence analysis (CCA) and permutation test; all from «vegan» package (OKSANEN et al., 2008).. RESULTS AND DISCUSSION. © EuroGeographics for the administrative boundaries. Figure 1. Locations of analyzed salt marshes We aim to establish the coastal frontier between the Eurosiberian and the Mediterranean regions, considering the distribution of salt marshes species and communities.. METHODS To understand species and syntaxa distribution we mainly used bibliographic records: the Asón Estuary (HERRERA, 1995), the Asturian estuaries (BUENO, 1997), the Ria Ortigueira (IZCO and SÁNCHEZ, 1996), the Minho Estuary (ALVES 2004, HONRADO et al., 2004), the Ria de Aveiro (PINTO DA SILVA and TELES, 1972; ALVES, 2004), the Tagus Estuary (COSTA, 1999), the Sado Estuary (COSTA, 1999), the Ria de Alvor (Costa and Lousã, 1992), the Ria Formosa (Costa et al., 1996), the Guadiana Estuary (LOUSÃ, 1986), the Guadalquivir Estuary (RIVAS-MARTÍNEZ et al., 1980), Punta del Sabinar (ALCARAZ et al., 1989), the Mar Menor (IZCO et al., 1984; RIVAS-MARTÍNEZ et al., 1984; ALCARAZ et al., 1991) and Santa Pola (IZCO et al., 1984; RIVAS-MARTÍNEZ et al., 1984; ALCARAZ et al., 1989). For the Lima, Cávado, Mondego, Tornada and Mira estuaries, as well as the Ria de Aveiro and the Óbidos Lagoon we used original data. In the halophytic areas of the Óbidos Lagoon and the Tornada and Mondego estuaries, although the rivers have a mediterranean regime with summer droughts, its flora and vegetation seems more similar to the Eurosiberian regions. In order to explain this difference sea-surface temperature data was collected. A central coordinate (latitude/longitude) was found for each salt marsh location (see figure 1). Monthly mean sea-surface temperatures (1981-1990) were obtained from SCHWEITZER (1993) for the closest coordinate available. Monthly minimum sea-surface temperatures (MMT) and the annual mean sea-surface temperatures (AMT) were calculated, for each location, based on the sea-surface data. The biogeographic typology of COSTA et al. (1999) and RIVASMARTÍNEZ (2007) was adopted in this work. For the botanical nomenclature CASTROVIEJO et al. (1986-2006), FRANCO (1971, 1984), FRANCO and ROCHA AFONSO (1994, 1998, 2003), RIVASMARTÍNEZ et al. (2002) were followed and for phytosociological data GÉHU and RIVAS-MARTÍNEZ (1981); RIVAS-MARTÍNEZ et al. (2001, 2002); RIVAS-MARTÍNEZ (2005). For the statistical analysis R software was used (R DEVELOPMENT CORE TEAM, 2008). Hierarchical clusters were obtained using «agnes()» function from «cluster» package (MAECHLER et al., 2005). On both presented dendrograms, UPGMA was used as cluster strategy and Jaccard distance as dissimilarity measure. Functions «vegdist()», «cca()» and. The dendrograms displayed in figures 2 and 3 show the existence of two strongly segregated groups: the first group is from the north of the Tagus River and clearly corresponds to the Eurosiberian Region salt marshes; the second, corresponds to salt marshes from the Mediterranean Region (including the Tagus River estuary). Moreover, within the Mediterranean branch two quite distinct subgroups, whose boundary is thought to be located next to the Straits of Gibraltar, can be observed. This separation may be related to the fact that salinization processes in the Mediterranean Sea are greatly influenced by the saline solution movements and by the presence of a saline phreatic sheet during summer time (CORRE, 1978), since tides are practically insignificant. On the Atlantic coast the main reason for the existence of halophytic areas is, on the contrary, soil submersion by seawater due to tides (SÁNCHEZ et al., 1998). Regarding the southwestern Iberian Peninsula, plant communities’ distribution has been influenced by both the depth and salt content of the phreatic sheet and the seawater submersion period (COSTA et al., 1996), which may explain the original combination of some Atlantic and Mediterranean plants and communities present on this area. Also within the Cantabrian-Atlantic Region branch two slightly different subgroups exist, although not consistently in the two dendrograms. The two referred main groups contain several exclusive species, in fact, Salicornia obscura, Armeria pubigera subsp. depilata, A. maritima, Baccharis halimifolia, Limonium humile, Puccinellia fasciculata, Salicornia dolichostachya, Suaeda maritima, Limonium binervosum, Matricaria maritima, Zostera marina, Plantago maritima, Festuca rubra subsp. pruinosa, Glaux maritima, Paspalum vaginatum, Puccinellia maritima, Elymus pycnanthus, Triglochin maritima, among others, only appear north of the Tagus River, while Arthrocnemum macrostachyum, Artemisia gallica, Cistanche phelypaea, Juncus subulatus, Puccinellia iberica, P. festuciformis, Triglochin bulbosa subsp. barrelieri, Cymodocea nodosa, Elytrigia elongata, Limoniastrum monopetalum, Salsola vermiculata, S. soda Beta macrocarpa, Frankenia boissieri, Limonium diffusum, Cressa cretica, Frankenia pulverulenta occur only southward. The halophytic areas between the Ria de Aveiro and the Tagus River host several. Figure 2. Cluster analysis using species data.. Journal of Coastal Research, Special Issue 56, 2009 1341.

(3) Costa et al.. Figure 3. Cluster analysis using sintaxa data. transitional elements: typical Mediterranean elements occur, e.g. Tamarix africana, Sarcocornia perennis subsp. alpini, Limonium ferulaceum, Polygonum equisetiforme, Suaeda splendens, while Eurosiberian species disappear, e.g. Puccinellia maritima, Glaux maritima, Festuca rubra subsp. pruinosa. However, the occurrence of Triglochin maritima, Elymus pycnanthus compels us to include them in the Cantabrian-Atlantic Region, as revealed by the cluster analyses. Salicornia ramosissima, S. patula, Sarcocornia perennis, Spartina maritima, Limonium vulgare, Frankenia laevis are Atlantic species that appear below the Tagus River but do not occur in the Mediterranean Sea. On the contrary, Suaeda vera is a Mediterranean element very rare in Eurosiberian territories. Frankenia corymbosa, Halocnemum strobilaceum, Limonium eugeniae, L. angustebracteatum, L. insigne, L. delicatulum, L. caesium, L. cossonianum, L. furfuraceum, L. santapolense, Puccinellia caespitosa, Suaeda spicata, Tamarix boveana, T. canariensis, Posidonia oceanica and Lygeum spartum only occur in the Mediterranean Basin. Aeluropus littoralis and Ruppia cirrhosa also appear in that area, although they can occur beyond the Straits of Gibraltar. Aster tripolium, Atriplex prostrata, Bolboschoenus maritimus var. maritimus, Bolboschoenus maritimus var. compactus, Carex extensa, Juncus acutus, J. maritimus, Halimione portulacoides, Sarcocornia fruticosa, Inula crithmoides, Ruppia maritima and Phragmites australis are instead examples of salt marsh ubiquitous species. The analyses of communities distribution coincides with that of the species distribution: Spergulario-Paspalenion vaginati, Glauco-Puccinellietalia, Elytrigietalia repentis, only appear north of the Tagus River, while Arthrocnemion macrostachyi, Salicornion patulae, Limonietalia, Juncetalia maritimi, Halodulo wrightii-Thalassietea testudinum, Frankenion pulverulentae, Pegano-Salsoletea, Stellarietea mediae show up southward. As for the Atlantic Zosteretea marinae communities, Zosteretum marinae occur only north of the Ria de Aveiro, whereas Zosteretum noltii has been encountered as far as Gibraltar. Differences can also be found in the Phragmitetea class: Scirpetum compacti, Scirpo compacti-Phragmitetum australis, Scirpetum compacti-tabernaemontani, Scirpetum pungentis are observed north of the Tagus River, though Scirpetum compactolittoralis occur south of this river. The two Spartinetea maritimae communities that occur in the Iberian Peninsula show a slightly different distribution: Spartinetum maritimae does not reach Gibraltar and Spartinetum densiflorae can only be found east of Algarve. The Cantabrian-Atlantic alliance Limonio ovalifolii-. Frankenion laevis has been found south of Galicia for the first time, with the association Puccinellio tenuifoliae-Limonietum daveaui, described below in appendix. Sarcocornietea fruticosae communities dominate from the Tagus River southward, although Sarcocornienion perennis associations are more frequent in the Atlantic coast (Puccinellio maritimae-Arthrocnemetum perennis, Obionetum portulacoidis), with just one community occurring between the Tagus Estuary and Gibraltar (Puccinellio ibericaeSarcocornietum perennis) and none in the Mediterranean Basin. Within Sarcocornienion fruticosae, Puccinellio maritimaeSarcocornietum fruticosae only appears in the coast north of the Mondego River, whereas Cistancho phelypaeae-Sarcocornietum fruticosae from the Tagus River southward. In this paper is presented the first Arthrocnemion macrostachyi, Sarcocornienion alpini association occurring north of Tagus Estuary, Triglochino maritimae-Sarcocornietum alpini, which is described in the appendix. The other association of this sub-alliance, Halimiono portulacoidis-Sarcocornietum alpini has only been observed southward. As previously referred, Arthrocnemion macrostachyi communities are typically Mediterranean and distinct associations exist in the southwestern Peninsula (Inulo crithmoidisArthrocnemetum macrostachyi, Limonio vulgare-Juncetum subulati) and in the Mediterranean Basin (Frankenio corymbosaeArthrocnemetum macrostachyi, Frankenio corymbosaeHalocnemetum fruticosi). Limonio vulgare-Juncetum subulati is an original association and is described in the appendix. Cistancho phelypaeae-Suaedetum verae has only been observed south of the Tagus River, while Agropyro pycnanthi-Suaedetum verae only in the Asturian estuaries. Limonietalia communities tend to appear mainly from Gibraltar eastward, anyway Polygono equisetiformisLimoniastretum monopetali, Limonietum ferulacei occur in the southeast of the Iberian Peninsula. The associations belonging to the halophytic alliance Carthamo arborescentis-Salsolion oppositifoliae of the Pegano-Salsoletea class are observed exclusively south of the Tagus River, often appearing east of Gibraltar. The same happens with the microforests of Nerio-Tamaricetea although Polygono equisetiformisTamaricetum africanae also occurs in two halophytic areas north of that river (Óbidos and Tornada) and extends to the Mediterranean Sea, while Inulo crithmoidis-Tamaricetum boveanae is merely observed in this basin, as well as Posidonietum oceanicae. For CCA, AMT and MMT were used as constraining variables, as expected to have direct physiologic influence on species and because they resulted significant (p<0.001) in permutation test. The presented plot uses site scores (see figure 4). A gap becomes evident between the two main groups formed by cluster analysis, which relates to AMT and MMT higher values in the Mediterranean sites, strengthening the two groups. CCA plot also confirms both the originality of Portuguese southwestern marshes (higher MMT) and the similarity between Portuguese northwest and Eurosiberian ones, showing that sea-surface temperature is noteworthy to understand the distribution of salt marshes flora.. CONCLUSION The halophytic territories of the Ria de Aveiro, the Mondego and Tornada rivers and the Óbidos Lagoon, though belonging to the Cantabrian-Atlantic Region, have a few Mediterranean species performing as a transition area between the two biogeographical regions. Our results confirm GÉHU and RIVAS-MARTÍNEZ (1983) suggestion: the authors proposed the Tagus River salt marsh as the boundary between the Eurosiberian and the Mediterranean regions, as far as the salt marshes communities are concerned. As for the Iberian Peninsula, they considered the sub-zone. Journal of Coastal Research, Special Issue 56, 2009 1342.

(4) Finding the Boundary between Eurosiberian and Mediterranean Salt Marshes. Figure 4. CCA for species data, AMT and MMT. Total inertia 1.5363; Constrained inertia 0.7110 and proportion 0.4628; Unconstrained inertia 0.8254 and proportion 0.5372; Eigenvalues CCA1 0.4338 CCA2 0.2772; Contribution to the mean squared contingency coefficient CCA1 0.2824 CCA2 0.4628; Accumulated constrained eigenvalues CCA1 0.6102 CCA2 1.0000. Cantabrian-Atlantic belonging to the Eurosiberian territory, and two other sub-zones (Mediterranean-Atlantic and Mediterranean) separated by the Straits of Gibraltar, although using only community data, confirming that salt marshes eastward and westward are distinct. It is proposed to classify all salt marshes north of Tagus Basin as Eurosiberian and those southward (including the Tagus ones) as Mediterranean.. APPENDIX Triglochino maritimae-Sarcocornietum alpini J.C. Costa, Neto, Izco ass. nova hoc loco (Sarcocornietea fruticosae, Sarcocornietalia fruticosae, Arthrocnemion macrostachyi, Sarcocornienion alpini) Halophytic community dominated by Sarcocornia perennis subsp. alpini, Triglochin maritima and Halimione portulacoides occurring in salt marshes in areas north of the Tagus River, in sandy-silty zones, occasionally flooded by brackish water, in mesomediterranean bioclimate and is a geovicariant of Halimiono portulacoidis-Sarcocornietum alpini, which belongs to the southeast of the Iberian Peninsula, south of the Tagus Estuary, in thermomediterranean territories. Differential species are Triglochin maritima, Puccinellia maritima and Plantago maritima. Typus: Barrosa/Lagoa de Óbidos (Caldas da Rainha), 2 m2: 3Sarcocornia perennis subsp. alpini, 2Triglochin maritima, 4Halimione portulacoides. Puccinellio tenuifoliae-Limonietum daveaui J.C. Costa, Neto & Portela-Pereira ass. nova hoc loco (Juncetea maritimi, GlaucoPuccinellietalia, Limonio ovalifolii-Frankenio laevis) Chamaephytic community in sandy-brackish soils, only occasionally touched by brackish water during equinoctial tides, although can be flooded by fresh water during winter or springtime. Limonium daveaui, Limonium ferulaceum, Puccinellia. tenuifolia, Halimione portulacoides, Frankenia laevis are the most reliable species. It occurs between the Óbidos Lagoon and S. Martinho do Porto (north of the Tagus River), in thermomediterranean subhumid bioclimate. Typus: Rio Tornada (Salir do Porto), 2 m2: 4Limonium daveaui, 3Puccinellia tenuifolia, 2Limonium ferulaceum, 1Frankenia laevis, 1Halimione portulacoides. Limonio vulgare-Juncetum subulati J.C. Costa, Neto, T. Almeida & Lousã ass. nova hoc loco (Sarcocornietea fruticosae, Sarcocornietalia fruticosae, Arthrocnemion macrostachyi, Arthrocnemenion macrostachyi) [Arthrocnemo glauci-Juncetum subulati sensu RIVAS-MARTÍNEZ et al. (1980, 1990), COSTA et al. (1997) non Arthrocnemo glauciJuncetum subulati Brulo & Funari 1976] Phytocoenoses dominated by Juncus subulatus, in depression or abandoned saltpans, flooded for a more or less long period by brackish water derived from autumn and winter rainfall, completely dried out during summer. It is found in saline-clayey soils, with a high sandy fraction, being the Iberian Arthrocnemion macrostachyi community that bear the longest period of flood. In its floristic characteristic composition are included: Juncus subulatus, Halimione portulacoides, Sarcocornia fruticosa, Limonium vulgare, Juncus maritimus, Aster tripolium, Arthrocnemum macrostachyum, Sarcocornia alpini, Polygonum equisetiforme, Limonium ferulaceum, Inula crithmoides, Elytrigia elongata, Triglochin barrelieri. Limonium vulgare, Limonium ferulaceum, Frankenia laevis, which are differential species of this new community distinguishing it from Arthrocnemo glauciJuncetum subulati and Elymo elongati-Juncetum subulati. It occurs in thermomediterranean dry bioclimate, within the Tagus and the Guadalquivir. Typus: Hortas, Rio Tejo (Alcochete), 4 m2: 4Juncus subulatus, 2Halimione portulacoides, 2Limonium ferulaceum, 1Limonium vulgare, 1Sarcocornia fruticosa, 1Polygonum equisetiforme, +Juncus maritimus, +Inula crithmoides.. LITERATURE CITED ALCARAZ, F., DÍAZ, T.E., RIVAS-MARTÍNEZ, S. and SÁNCHEZGÓMEZ, P., 1989. 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