Guillermo Curado

Contrasting strategies to cope with drought by invasive and endemic species of Lantana in Galapagos

This study compares how Lantana camara, an invasive species, and L. peduncularis, an autochthonous one, cope with drought in Galapagos. Soil surface temperature was the abiotic environmental parameter that best explained variations in photosynthetic stress. Higher soil surface temperatures were recorded in the lowlands and in rain-shadow areas, which were also the driest areas. L. peduncularis, with a shallow root system, behaved as a drought-tolerant species, showing lower relative growth rates, which decreased with leaf water content and higher photosynthetic stress levels in the lowlands and in a northwest rain-shadow area in comparison with higher and wetter locations. Its basal and maximal fluorescences decreased at lower altitudes, reflecting the recorded drops in chlorophyll concentration. In contrast, L. camara with a deep root system behaved as a drought-avoiding species, showing leaf and relative water contents higher than 55% and avoiding permanent damage to its photosynthetic apparatus even in the driest area where it showed very low chlorophyll content. Its relative growth rate decreased more in dry areas in comparison to wetter zones than did that of L. peduncularis, even though it had greater water content. Furthermore, L. camara showed higher water contents, growth rate, and lower photosynthetic stress levels than L. peduncularis in the arid lowlands. Thus, L. peduncularis maintained lower maximum quantum efficiency of photosystem II photochemistry (Fv/Fm) than L. camara even at sunrise, due to higher basal fluorescence values with similar maximal fluorescence, which indicated permanent damage to PSII reaction centres. Our results help to explain the success and limitations of L. camara in the invasion of arid and sub-arid environments.

Potential of Spartina maritima in Restored Salt Marshes for Phytoremediation of Metals in a Highly Polluted Estuary

Sedimentary abiotic environment, and concentration and stock of nine metals were analyzed in vegetation and sediments to evaluate the phytoremediation capacity of restored Spartina maritima prairies in the highly polluted Odiel Marshes (SW Iberian Peninsula). Samples were collected in two 10 –m long rows parallel to the tidal line at two sediments depths (0–2 cm and 2–20 cm). Metal concentrations were measured by inductively coupled plasma spectroscopy. Iron, aluminum, copper, and zinc were the most concentrated metals. Every metal, except nickel, showed higher concentration in the root zone than at the sediment surface, with values as high as ca. 70 g Fe kg–1. The highest metal concentrations in S. maritima tissues were recorded in its roots (maximum for iron in Spartina roots: 4160.2 ± 945.3 mg kg–1). Concentrations of aluminum and iron in leaves and roots were higher than in superficial sediments. Rhizosediments showed higher concentrations of every metal than plant tissues, except for nickel. Sediment metal stock in the first 20 cm deep was ca. 170.89 t ha–1. Restored S. maritima prairies, with relative cover of 62 ± 6%, accumulated ca. 22 kg metals ha–1. Our results show S. maritima to be an useful biotool for phytoremediation projects in European salt marshes.

Plant Zonation in Restored, Nonrestored, and Preserved Spartina maritima Salt Marshes

ABSTRACT Curado, G.; Rubio-Casal, A.E.; Figueroa, E., and Castillo, J.M., 2014. Plant zonation in restored, nonrestored, and preserved Spartina maritima salt marshes. This study analyzes the vegetation zonation and the abiotic environment (sediment elevation, pH, redox potential, and electrical conductivity) 2.5 years after salt marsh restoration using Spartina maritima and Sarcocornia perennis plantations in the Odiel Marshes (SW Iberian Peninsula) in comparison with preserved and degraded marshes. Restored marshes presented higher species richness (10 spp.) than nonrestored (6 spp.) and preserved (3 spp.) marshes, as a result of milder abiotic conditions (more oxygenated sediments than preserved marshes) and higher habitat diversity (sandy patches at higher elevations). Marshes restored using S. maritima (planted at a density of 1 clump m−2) achieved a similar relative cover to preserved marshes (ca. 50%) 2.5 years after transplanting. Spartina maritima showed higher tiller height in preserved (40 ± 2 cm) than in restored marshes (34 ± 1 cm). Sarcocornia perennis cover was similar in the three areas, being concentrated at higher elevations in the tidal gradient. Our results show the success from the point of view of vegetation of restoring European low salt marshes using S. maritima and S. perennis plantations, since they are able to reproduce, 2.5 years after restoration, the typical zonation pattern.

Avian communities in Spartina maritima restored and non-restored salt marshes

Capsule Salt marsh restoration with the native halophytes Spartina maritima and Zostera noltii can lead to significant improvement in habitat, increasing bird diversity over a 2-year period. Aims To assess the evolution of the avian communities in S. maritima restored salt marshes 2 years after planting, in comparison with adjacent non-restored marshes in the Odiel Marshes (southwest Iberian Peninsula). Methods Bird censuses were conducted from October 2008 to September 2009 in rectangular plots in three locations in both restored and non-restored marshes during high tides and low tides. Results A total of 44 bird species, including 20 shorebird species, were recorded. Most species belonged to Charadriidae, Scolopacidae, Laridae and Sterninae. Eight threatened bird species were recorded in restored marshes. Ecological diversity of the avian communities varied between 1.13 and 1.77. Restored marshes showed higher ecological diversity and evenness and lower Simpson dominance index than non-restored marshes. Conclusion Salt marsh restoration with the native halophytes S. maritima and Z. noltii can lead to significant short-term (over 2 years) improvements in bird diversity.

Public Perceptions and Uses of Natural and Restored Salt Marshes

Abstract Only a few restoration projects incorporate public perception in their monitoring. However, participation of local people is a key process if social benefits are to be achieved. This study analyses, through a survey, citizens’ perceptions and usage of natural and restored coastal marshes in the city of Huelva (southwest Iberian Peninsula, Spain), as well as landscape preferences. Most of Huelva’s citizens recognised the benefits of coastal marshes (75%), a perception which increased with level of education. The majority of the respondents showed a low level of knowledge about the eco-lo-gical services and functions of salt marshes. In addition, visitor numbers to the studied restoration project increased by 27% after restoration. Regarding landscape preferences, most of the respondents preferred the native Chenopodiaceae salt marsh, and the native Spartina maritima landscape was chosen less often. In light of our results, environmental education campaigns should be carried out in the city of Huelva to increase its citizens’ knowledge of salt marshes.

Handling High Soil Trace Elements Pollution: Case Study of the Odiel and Tinto Rivers Estuary and the Accompanying Salt Marshes (Southwest Iberian Peninsula)

Salt marshes are being increasingly polluted by trace elements, and the design and implementation of management actions adapted to each particular situation are necessary. Salt marshes developed at one of the most heavy metal-polluted systems in the world, the Odiel and Tinto joint estuary, are threatened by high pollution levels, erosion and the invasion of the alien plant species Spartina densiflora, despite the high ecological values recognized by regional to international protection figures. Soft management on these marshes tries to preserve the equilibrium between conservation and decontamination. The ability of key native halophytes in the area to phytoextract or phytostabilizate trace elements has been taking into account. A local restoration project has resulted in a rapid recovery of the native prairies of low tidal marshes, dominated by S. maritima, becoming a promising tool to phytostabilize eroding areas in European marshes. These prairies also seem to stop the advance of the alien S. densiflora invasion and prevent erosion. On the other hand, areas invaded by S. densiflora are difficult to manage due to the acidity and pollution level of sediments preventing the establishment of any other plant species. Despite its invasive character, S. densiflora avoid at present the removal of highly toxic sediments and the trace element release to the food chain in this area.

Realized niche and spatial pattern of native and exotic halophyte hybrids

Interspecific hybridization is an important and common evolutionary mechanism, but field-based evaluations of changes in realized niches and zonation patterns of native and exotic hybrids relative to those of their parental plant species are rare. Would native hybrids forming hybrid zones between their parental species show realized niches similar to that of their parents, whereas would exotic hybrids show larger realized niches than their parents, and alter zonation patterns of native species? To address these questions, we examined key sediment characteristics in plots representing realized niches of native Sarcocornia hybrids, invasive Spartina hybrids and parental species in 14 salt marshes from four estuaries in the Gulf of Cadiz, Southwest Iberian Peninsula. In one representative marsh, the presence of plant taxa relative to intertidal plant zonation was recorded. Results documented that native and fertile hybrids of Sarcocornia had similar realized niche dimensions as their parental species and co-occurred with other plant species, supporting community diversity. However, exotic sterile hybrids of Spartina had realized niche dimensions lower than those of their parental species and occurred in monocultures. The native hybrids played a community structuring role, whereas the exotic Spartina hybrids were a disruptive influence that changed native halophyte zonation pattern and decreased diversity. This negative functional role could intensify if the sterile hybrids evolve and become fertile. Our study suggests the ecological niche dimension concept is an important tool for understanding species roles in ecosystems, incorporating many ideas from the individual to ecosystem levels.