Browsing by Subject "Human impact"

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    Functional redundancy as a tool for bioassessment: A test using riparian vegetation
    (Elsevier, 2016-06-05) Bruno, Daniel; Gutiérrez Cánovas, Cayetano; Velasco, Josefa; Sánchez Fernández, David; Ecología e Hidrología
    There is an urgent need to track how natural systems are responding to global change in order to better guide management efforts. Traditionally, taxonomically based metrics have been used as indicators of ecosystem integrity and conservation status. However, functional approaches offer promising advantages that can improve bioassessment performance. In this study,we aimto test the applicability of functional redundancy (FR), a functional feature related to the stability, resistance and resilience of ecosystems, as a tool for bioassessment, looking at woody riparian communities in particular. We used linear mixed-effect models to investigate the response of FR and other traditional biomonitoring indices to natural (drought duration) and anthropogenic stress gradients (flow regulation and agriculture) in a Mediterranean basin. Such indices include species richness, a taxonomic index, and the Riparian Quality Index, which is an index of ecological status. Then, we explored the ability of FR and the other indices to discriminate between different intensities of human alteration. FR showed higher explanatory capacity in response to multiple stressors, although we found significant negative relationships between all the biological indices (taxonomic, functional and ecological quality) and stress gradients. In addition, FRwas the most accurate index to discriminate among different categories of human alteration in both perennial and intermittent river reaches, which allowed us to set threshold values to identify undisturbed (reference condition), moderately disturbed and highly disturbed reaches in the two types of river. Using these thresholds and the best-fitting model, we generated a map of human impact on the functional redundancy of riparian communities for all the stretches of the river network. Our results demonstrate that FR presents clear advantages over traditional methods, which suggests that it should be part of the biomonitoring toolbox used for environmental management so as to obtain better predictions of ecosystem response to environmental changes.
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    Quotas regulation is necessary but not sufficient to mitigate the impact of SCUBA diving in a highly visited marine protected area
    (Elsevier, 2021-10-21) Caló, Antonio; Hernández Andreu, Ramón; García Charton, José Antonio; Pereñíguez López, José Manuel; Ecología e Hidrología
    When effectively managed, Marine Protected Areas (MPAs) can produce wide ecosystem benefits that can foster, directly and indirectly, local economies. Tourism is one of the sectors mainly benefited by the effect of conservation. SCUBA diving represents an important tourism activity, especially in the context of MPAs, where it is one of the few activities often fostered rather than limited, for its capacity to integrate environmental and socio-economic sustainability. However, SCUBA diving can also produce negative impacts on the environment when tourism frequentation exceeds a sustainable threshold, these potentially generating negative effects on the sector itself. In this study, we (1) investigated the impact of SCUBA diving in one of the most frequented diving areas of the Mediterranean Sea (Cabo de Palos – Islas Hormigas marine reserve), and (2) assessed the potential benefits over time related to the adoption of a regulation change for the diving activity (i.e., formally adoption of diving quotas). Specifically, we compared demographic (density of alive and dead colonies) and morphometric (height, width and complexity) characteristics of the false coral (Myriapora truncata) between dived and fully protected (non-dived) locations over four diving seasons (one before and three after the change in diving quotas). The density of alive colonies of the false coral was, on average, six times lower in dived locations compared to controls, highlighting a clear impact of SCUBA diving (consistent over time). Colonies were also significantly smaller in dived locations. The diving quotas produced a significant reduction of the ratio dead/total colonies in the dived locations soon after their adoption, but these benefits disappeared over the following years, possibly due to a gradual decline in operators' and divers’ observance and concern, rather than an increasing number of dives. This suggests that the adoption of effective regulations is crucial for the environmental sustainability of diving tourism in protected areas and can provide positive effects, but an effort is needed to ensure that compliance is consistent over time, and that low-impact diving practices are adopted by this important recreational sector.