As the number of introduced species keeps increasing unabatedly, identifying and prioritising current and potential Invasive Alien Species (IAS) has become essential to manage them. Horizon Scanning (HS), defined as an exploration of potential threats, is considered a fundamental component of IAS management. By combining scientific knowledge on taxa with expert opinion, we identified the most relevant aquatic IAS in the Iberian Peninsula, i.e., those with the greatest geographic extent (or probability of introduction), severe ecological, economic and human health impacts, greatest difficulty and acceptability of management. We highlighted the 126 most relevant IAS already present in Iberian inland waters (i.e., Concern list) and 89 with a high probability of being introduced in the near future (i.e., Alert list), of which 24 and 10 IAS, respectively, were considered as a management priority after receiving the highest scores in the expert assessment (i.e., top-ranked IAS). In both lists, aquatic IAS belonging to the four thematic groups (plants, freshwater invertebrates, estuarine invertebrates, and vertebrates) were identified as having been introduced through various pathways from different regions of the world and classified according to their main functional feeding groups. Also, the latest update of the list of IAS of Union concern pursuant to Regulation (EU) No 1143/2014 includes only 12 top-ranked IAS identified for the Iberian Peninsula, while the national lists incorporate the vast majority of them. This fact underlines the great importance of taxa prioritisation exercises at biogeographical scales as a step prior to risk analyses and their inclusion in national lists. This HS provides a robust assessment and a cost-effective strategy for decision-makers and stakeholders to prioritise the use of limited resources for IAS prevention and management. Although applied at a transnational level in a European biodiversity hotspot, this approach is designed for potential application at any geographical or administrative scale, including the continental one.
Ecosystem , Introduced Species , Animals , Humans , Biodiversity , Vertebrates , Invertebrates
Halophyte species growing under stressful conditions, such as the annual species of the Salicornia genus, have been recognized as a source of metabolites of pharmacological and nutraceutical interest. Therefore, planning the extraction of individual plants from wild populations in a sustainable way is especially important in the case of annual species. We studied the environmental matrix and population dynamic of four Salicornia ramosissima populations growing at two elevations in salt pans under a Mediterranean climate. In elevated areas, S. ramosissima populations presented maximum plant densities of between 628-6288 plants m-2 that remained almost constant until fruiting. In contrast, populations in depressed zones presented five-times greater soil-seed-bank densities and maximum plant densities than populations in elevated zones. In this context, populations in depressed zones lost c. 60% of their maximum plant densities from the end of spring and through summer. In whatever way the environmental matrix seemed to control the population dynamic of S. ramosissima in depressed zones, the effects of a stressful environment would interact with plant densities. In this sense, we recorded the density-dependent mortality for the densest population (max. 51,558 plants m-2). Our results are useful for planning a sustainable harvesting of natural populations of S. ramosissima.
Seed germination and seedling establishment are very sensitive plant stages to metal pollution. Many halophyte species colonizing salt marshes are able to germinate and establish in highly contaminated habitats and low marsh halophyte species seem to show higher tolerance to metals than high marsh species. We analyzed the effects of copper, zinc and nickel in concentrations up to 2000 µM on seed germination and seedling growth in two closely related species of Sarcocornia, S. perennis, a low marsh species, and S. fruticosa, a high marsh species. Germination of both halophytes was not affected by any metal concentration, and their seedling growth, mainly radicle length, was reduced by increasing metal concentrations. Seedlings of S. perennis showed higher tolerance to the three metals than those of S. fruticosa. Our results are useful for designing ecotoxicological bioassays and planning phytoremediation projects in salt marshes.
Germination , Metals, Heavy , Metals, Heavy/toxicity , Salt-Tolerant Plants , Seedlings , Seeds , Wetlands
BACKGROUND: The flowering phenology pattern of Atriplex halimus was studied in a Mediterranean habitat in order to analyze protandry effectiveness. Fruit set evolution was recorded over two years and the impact of pre-dispersal predation by insects was also evaluated. RESULTS: The flowering phenology coincided in 2006 and 2007, starting in mid-July and reaching full flowering at the end of August in both years. Inflorescences are composed of glomerules with 8.78 ± 2.79 male flowers and 4.57 ± 2.58 female flowers, with no significant differences in position on the inflorescence. The peaks of male and female flower anthesis were reached in mid-August, but the male maximum occurred one week before the female. Plants at the start of flowering only bear male flowers, but female flowers soon appear. Fruit set starts at the end of August; all the flowers were transformed into fruit by mid-September and their development continued to the beginning of October, when fruit structures had matured and began to drop. Fruit predation started at the end of September and reached maximum intensity in mid-October. CONCLUSIONS: At population level, male and female flowers seemed to open in the same weeks, but at plant and glomerule level male flowers opened one week before the females. Fruit predation levels were 62.42 and 43.14% in 2006 and 2007 respectively, with no significant differences between different parts of the inflorescence. And larvae of Coleophoridae were the most abundant predators.
