Invasive crayfish are a worldwide problem for aquatic ecosystems. So far, no control method has proven successful. Field data from invaded streams have suggested that physical structures may hamper ...the spread rate of invasive crayfish into new areas. However, given the difficulties for carrying out dam construction in natural habitats, data about their effectiveness in incipient invading populations are practically nonexistent. This paper evaluates the effectiveness of small dams to contain the advance of an incipient population of the invasive
Procambarus clarkii in a mountain stream harboring the European southernmost population of the endangered
Austropotamobius pallipes. The management strategy involved the construction of 3 artificial small (<3
m high) dams that were complemented with specific design solutions to increase their theoretical efficacy. Catch Per Unit Effort (CPUE) obtained during monitoring surveys carried out for 4 years were used as an indicator of containment effectiveness. The dams successfully prevented
Procambarus clarkii from extending its range into the area occupied by
A. pallipes. In addition, regardless of whether the construction of new dams isolated the leading edge of the invading population between two dams, the CPUE declined to below detectable limits. Therefore, dams are suggested to effectively stop, or at least hinder, the advance of invasive crayfish. Long-term monitoring is recommended to verify the on-going success of the dams in preventing upstream invasion.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The increasing number of invasive species and their effects on wildlife conservation, together with a lack of public resources, make it necessary to prioritize management actions. In practice, ...management decisions are often reached on the basis of subjective reasoning rather than scientific evidence. To develop a more evidence-based and efficient management of biological invasions, decision tools (e.g. multi-criteria frameworks) that help managers prioritize actions most efficiently are key. In this paper we review to what degree such decision tools are currently available. We used a literature search to identify relevant studies. Our analysis indicates that available studies are largely biased towards risk analysis and that only a few authors have proposed cost-benefit or multi-criteria frameworks for decision making. Until now, these frameworks have only been applied at limited regional scales but they could be applied more widely. Our review also shows critical biases in the geographical focus, habitats, and taxonomic groups of available studies. Most studies have focused on Europe, North America or Australia; other continents have largely been ignored. The majority of studies have focused on terrestrial plants; other habitats and taxonomic groups have been poorly covered. Most studies have focused on a single invasive species but practical management tools should consider a wide variety of invaders. We conclude with suggestions for developing improved decision tools.
Despite the increasing number of invasive species, protocols devoted to assess the feasibility (i.e., probability of success or failure) of management actions in the field are scarce, yet success ...depends on a broad scope of issues beyond the biology of species and the ecosystem to be managed. In this paper we make a retrospective analysis of 90 actions and management proposals developed in Andalusia (southern Spain) in 2004 to 2018. Actions included 59 terrestrial and aquatic taxa. We identified items that in case of deficiency were responsible for either the rejection of action proposals (
n
= 44) or failure of implemented actions for which the goal was not achieved (
n
= 22). The most frequent deficiencies included the absence of funding during the necessary time to achieve the goals, the risk of reinvasion and an insufficient removal rate to achieve the specific objective. Based on the deficiencies found, we built a comprehensive, broad-scope compliance checklist to assist decision-makers to identify deficiencies before action. In addition, implemented actions for which the goal was achieved (
n
= 24) were used for validating the checklist. The checklist contains 40 items related to IAS features, administrative features, methodology effectiveness, efficiency and impacts of the action, and invaded ecosystem features. The checklist is valid across all taxa and habitats. The use of this checklist will help reduce the degree of arbitrariness and subjectivity of actions aimed at managing IAS, and a more efficient use of resources.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Aerial images of the high summits of the Spanish Central Range reveal significant changes in vegetation over the period 1957 to 1991. These changes include the replacement of high‐mountain grassland ...communities dominated by Festuca aragonensis, typical of the Cryoro‐Mediterranean belt, by shrub patches of Juniperus communis ssp. alpina and Cytisus oromediterraneus from lower altitudes (Oro‐Mediterranean belt). Climatic data indicate a shift towards warmer conditions in this mountainous region since the 1940s, with the shift being particularly marked from 1960. Changes include significantly higher minimum and maximum temperatures, fewer days with snow cover and a redistribution of monthly rainfall. Total yearly precipitation showed no significant variation. There were no marked changes in land use during the time frame considered, although there were minor changes in grazing species in the 19th century. It is hypothesized that the advance of woody species into higher altitudes is probably related to climate change, which could have acted in conjunction with discrete variations in landscape management. The pronounced changes observed in the plant communities of the area reflect the susceptibility of high‐mountain Mediterranean species to environmental change.
Full text
Available for:
BFBNIB, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
A rapid response action carried out against the invasion of water hyacinth (Eichhornia crassipes) in the Guadalquivir River branch in Seville (Southern Spain) is described and analyzed. Removal was ...implemented and coordinated by the regional environmental Council, National security forces and public companies. Immediately after its detection, the distribution and abundance of water hyacinth, and the possible origin of introduction were assessed as the basis for selecting a feasible removal method. Plants were scattered across 110 ha and a perimeter of 8.4 km. A total biomass of 1,931 kg (fresh weight) was removed between May and December 2021 by combining manual removal from water using inflatable boats, floating booms, wetsuits and fishing waders, as well as removal from the shore. In total, the action cost ca. €22,500. Most biomass (83%) was removed during the initial control phase (one month). However, most of the efforts and costs (83%) were made in the following seven months, especially for monitoring and follow-up treatments. Rapid response avoided the growth, blooming and spread that could be expected in summer, coinciding with the optimal growing conditions. Moreover, rapid response reduced ca. 50 times the biomass and control costs with respect to a delayed action (i.e., after summer). Despite the fact that monitoring required a higher effort and cost than the initial control phase, it altogether represented a great cost saving as the invasion was kept at bay. The coordination between the regional Council, National security forces and public companies has taken advantage of the specific strengths of each one of them, achieving the shortest possible response time.
Biological invasions are a major component of global change with increasing effects on natural ecosystems and human societies. Here, we aim to assess the relationship between plant invader species ...attributes and the extent of their distribution range size, at the same time that we assess the association between environmental factors and plant invader species richness. Spain, Mediterranean region. From the species perspective, we calculated the distribution range size of the 106 vascular plant invaders listed in a recently published atlas of alien plant species in Spain. Range size was used as an estimation of the degree of invasion success of the species. To model variation in range size between species as a function of a set of species attributes, we adopted the framework of the generalized linear mixed models because they allow the incorporation of taxonomic categories as nested random factors to control for phylogenetic relationships. From the invaded site perspective, we determined invader plant species richness as the number of species for each 10 x 10 km Universal Transverse Mercator (UTM) grid. For each grid cell, we estimated variables concerning landscape, topography, climate and human settlement. Then, we performed a generalized linear mixed model incorporating a defined spatial correlation structure to assess the relationship between plant invader richness and the environmental predictors. From the species perspective, wind dispersal and minimum residence time appeared to favour invasion success. From the invaded site perspective, we identified high anthropogenic disturbance, low altitude, short distance to the coastline and dry, hot weather as the main correlates to UTM grid cell invader richness. According to these results, an increasing importance of man-modified ecosystems and global warming in the Mediterranean region should facilitate the expansion of plant invaders, especially wind-dispersed species, leading to the accumulation of invasive species in some sites (i.e. invasion hot spots).
Full text
Available for:
BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NMLJ, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
The red swamp crayfish
Procambarus clarkii
is the most widespread invasive crayfish in Europe, and responsible for a plethora of negative impacts on aquatic ecosystems. Most capture methods used for ...controlling crayfish populations have a bias towards the capture of adults, however, the removal of the young-of-the-year crayfish (YOY) may be essential for achieving effective control of invasive populations. This paper analysed the crayfish caught during a management campaign carried out in five permanent stream pools from southern Spain. We compared size structure, CPUE and sex-ratio obtained with two control methods: cylindrical traps (a method commonly used in crayfish management) and horizontal hauls using a fine-mesh net (inspired by zooplankton sampling techniques). Horizontal hauls showed a higher selectivity for catching YOY and higher efficiency (eight-fold) than traps. The combined use of both gears increased total catch by 46%. Our results suggest that YOY may be sharply underestimated if only cylindrical traps are used. The YOY cohort represented 60% of the total catch during the management campaign. Therefore, active netting with a fine mesh may be a complementary method to the use of traps in order to manage invasive populations of
P. clarkii
and may provide a better understanding of the structure and dynamics of invasive crayfish populations.
L'écrevisse rouge de Lousiane
Procambarus clarkii
est l'écrevisse invasive la plus répandue en Europe et responsable d'un large éventail d'impacts négatifs sur les écosystèmes aquatiques. La plupart des méthodes de capture utilisées pour capturer et contrôler les populations d'écrevisses ont un biais en faveur de la capture des adultes, cependant, l'élimination des jeunes écrevisses de l'année (YOY) peut être essentielle pour parvenir à un contrôle efficace des populations envahissantes. Cet article a analysé les écrevisses capturées au cours d'une campagne de gestion de deux semaines menée dans cinq bassins de cours d'eau permanents du sud de l'Espagne. Nous avons comparé la structure de taille, la CPUE et le sex-ratio obtenus avec deux méthodes de contrôle: les pièges cylindriques (une méthode couramment utilisée dans la gestion des écrevisses) et les traits horizontaux à l'aide d'un filet à mailles fines (inspiré des techniques d'échantillonnage du zooplancton). Les traits horizontaux ont montré une plus grande sélectivité pour la capture de YOY et une efficacité plus élevée (huit fois) que les pièges. L'utilisation combinée des deux engins a augmenté les captures totales de 46%. Nos résultats suggèrent que YOY peut être fortement sous-estimé si seuls des pièges cylindriques sont utilisés. La cohorte YOY représentait 60% des captures totales pendant la campagne de gestion. Par conséquent, le filet actif à mailles fines peut être une méthode complémentaire à l'utilisation de pièges afin de gérer les populations envahissantes de
P. clarkii
et peut fournir une meilleure compréhension de la structure et de la dynamique des populations d'écrevisses invasives.
We evaluated the ecological success of the manual removal of Carpobrotus species, a putative hybrid complex of a South African perennial mat-forming plant, by comparing treated, noninvaded, and ...invaded plots across coastal Andalucía in southern Spain. As a measure of the management effectiveness, we quantified the density of Carpobrotus seedlings and resprouts in treated plots one year after treatment. Response of the plant community to removal was assessed by comparing native species richness, cover, diversity, and species composition among treatments. Removal greatly reduced to a great extent Carpobrotus density. However, successful control will require repeated hand-pulling treatments. Treated plots had a significant increase in species richness, especially annual plants, compared to invaded plots, but both had the same native plant cover and diversity. We found similar species composition between removal and noninvaded plots, indicating that revegetation is not necessary. Long-term monitoring is necessary to determine whether these observed patterns of community response are transient or stable through succession.
Full text
Available for:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
PDF
