Dani Boix

Succession of the animal community in a Mediterranean temporary pond

Abstract Successional changes in the animal community of a temporary pond on the Iberian Peninsula were analyzed based on taxon abundance and the biomass–size spectrum. Changes in the community were studied over 6 hydroperiods during 1996 and 1997. Community dynamics were analyzed using multivariate analysis and a new statistical approach based on the Pareto probability distribution. Three successional phases could be distinguished on the basis of changes in taxon abundance. This pattern is consistent with the 3-phase model reported in other temporary ponds in temperate latitudes. The 1st and 3rd phases corresponded to changes in hydrological factors (pond drying, water turnover) and to seasonality, whereas the 2nd phase corresponded to more stable hydrological conditions. Five successional phases could be distinguished on the basis of biomass–size spectra with similar structure. These phases were consistent with variations over time of parameter c of Pareto Model I. The 3 middle phases (II, III, and IV) identified using the size-spectrum approach corresponded to the single middle phase identified using the taxonomic approach. Thus, community changes during the middle phase were better resolved by analysis of the biomass–size spectrum than by analysis of taxon abundance.

Zooplankton structure and dynamics in permanent and temporary Mediterranean salt marshes : taxon- based and size-based approaches

Differences between zooplankton structure (species abundance and size distribution) and dynamics of permanent and temporary basins of a Mediterranean salt marsh (Emporda Wetlands, NE Spain) were analysed by means of taxon-based and size-based approaches. These basins are shallow bodies of water which are occasionally connected. They were isolated after water retreat from a broadly flooded, low-lying area close to the open sea. Although temporary and permanent basins show no differences in the most abundant zooplankton species, they differ in their zooplankton diversity, temporal pattern and size structure. The zooplankton assemblages of temporary basins exhibit a temporal pattern with six phases, which are conditioned to the hydrological cycle, each one dominated by one species, whereas in the permanent basin this temporal pattern shows only two phases. Zooplankton size distribution of the temporary basins is dominated by large sizes (copepodites and copepods) while the permanent basin is dominated mainly by small sizes (rotifera and nauplii of copepods). In the temporary basins, the shape of the biomass size spectrum changes according to the hydrological cycle and reflects the dynamics of the ecological interactions among zooplankton species. Differences in the zooplankton composition and dynamics of the permanent basin are not a consequence of water permanence but of the ecological interactions among species involved. The presence of a stable fish population in the permanent waters may explain the high values of zooplankton diversity and the low densities of large zooplankton.

The ecological role of ponds in a changing world

The fifth conference of the European Pond Conservation Network (Luxembourg, June 2012) brought together researchers, environmental managers, and other stakeholders with the aim to share state-of-the-art knowledge on the ecology, management, and conservation of ponds in the context of the many challenges facing the wider water environment. Although well-known ecological patterns apply to most ponds in Europe and elsewhere, recent data highlight that part of the environmental variables governing pond biodiversity remain specific to climatic/biogeographic regions and to elevation ranges, suggesting that, in addition to common practice, management plans should include range-specific measures. Beyond the contribution of individual ponds to the aquatic and terrestrial life, connected networks of ponds are vital in the provision of new climate space as a response to global climate change, by allowing the observed northward and/or upward movements of species. In terms of services, ponds offer sustainable solutions to key issues of water management and climate change such as nutrient retention, rainfall interception, or carbon sequestration. While the ecological role of ponds is now well-established, authoritative research-based advice remains needed to inform future direction in the conservation of small water bodies and to further bridge the gap between science and practice.

Spatial and temporal patterns of pioneer macrofauna in recently created ponds: taxonomic and functional approaches

Man-made ponds are often created to compensate for the loss and degradation of wetlands, but little is known about the processes taking place in these artificial environments, especially at a community level. The macrofaunal assemblage and water chemistry of newly created ponds in three nearby areas in the NE Iberian Peninsula were studied during the first year of life of these ponds in order to (i) detect if any invertebrate assemblage structure change was taking place, (ii) evaluate the effect of local factors on the invertebrate assemblage in each site, and (iii) compare the information obtained by taxonomic and functional approaches. Although invertebrate colonization was rapid, no relevant changes in assemblage parameters were related to time, implying that more time may be needed to detect successional changes in invertebrate assemblages. Local factors—especially those related to hydrological stability—produced notable differences both in the assemblage parameters and in the taxonomic and functional compositions of the invertebrate fauna. Finally, information provided by the functional approach was redundant with respect to that obtained by the classical taxonomic approach: in these newly created systems, the high dominance of a small number of taxa makes the functional approach a simple biological traits analysis of the few dominant species.

Variability of benthic assemblages in relation to the hydrological pattern in Mediterranean salt marshes (Empordà wetlands, NE Iberian Peninsula)

The structure and composition of benthic assemblages (organisms > 100 μm) and the main factors which control them were studied in the coastal basins of the Emporda wetlands (NE Iberian Peninsula). Five coastal basins were sampled in three different conditions during one hydroperiod (1997-1998): (1) one month after the main autumnal inundation when the water level was high; (2) in the middle of the hydroperiod; and (3) when the basins were close to desiccation. Based on the hydrological pattern, three types of basins were distinguished: non-disturbed permanent waters (type 1), non-disturbed temporary waters (type 2), and disturbed temporary waters (type 3). These three types are in agreement with the classification result from the benthic assemblage composition. The type 1 basins, where more stable environmental conditions were found, had an assemblage characterised by a high density of individuals, total biomass and diversity. The assemblage of type 2 basins had lower richness and diversity values with little temporal variability. The high frequency of freshwater inputs in type 3 basins causes a high taxonomic singularity and high temporal variability of species richness and diversity. The main environmental parameters (salinity, sand percentage, total phosphorus from the sediment, and total organic carbon from the water) related to the structure of benthic assemblages, also discriminating three groups, were coincident with the three types derived from distinct hydrological patterns. Thus, water regime summarises the physical factors which ultimately determine benthic fauna.

Identifying key environmental factors related to plant and crustacean assemblages in Mediterranean temporary ponds

The current interest in Mediterranean temporary wet habitats, considered to be habitats of European Community Interest, is mainly due to their characteristic flora and fauna. Several contributions characterize each of these two components separately, but considering them simultaneously could reveal possible interactions and a more complete view of the habitat that would be useful to improve conservation measures. This paper investigates crustacean and plant assemblages in six Mediterranean temporary ponds and their relationship with several environmental variables. Significant positive relationships were found between species richness and Shannon diversity index of plant and crustacean assemblages. Crustaceans had a higher similarity among ponds than plants and, consequently, each pond had a more characteristic assemblage of plants than of crustaceans. The two groups showed a different sensitivity to environmental factors and only two factors affected both: altitude and surface area of the wet system. Disturbances (e.g. grazing by cattle) and pond size were very important for plants, whereas they were irrelevant for crustaceans. On the other hand, distance to the nearest pond, hydroperiod length, and water nitrogen were only important for crustaceans. Although similar trends on richness and diversity were observed for both biotic groups, the use of only one of them for conservation programs would not be sufficient. Our results suggest that simultaneously taking into account several community components would result in a better understanding of ecosystem functionality.

Effects of Temperature, Salinity and Fish in Structuring the Macroinvertebrate Community in Shallow Lakes: Implications for Effects of Climate Change

Climate warming may lead to changes in the trophic structure and diversity of shallow lakes as a combined effect of increased temperature and salinity and likely increased strength of trophic interactions. We investigated the potential effects of temperature, salinity and fish on the plant-associated macroinvertebrate community by introducing artificial plants in eight comparable shallow brackish lakes located in two climatic regions of contrasting temperature: cold-temperate and Mediterranean. In both regions, lakes covered a salinity gradient from freshwater to oligohaline waters. We undertook day and night-time sampling of macroinvertebrates associated with the artificial plants and fish and free-swimming macroinvertebrate predators within artificial plants and in pelagic areas. Our results showed marked differences in the trophic structure between cold and warm shallow lakes. Plant-associated macroinvertebrates and free-swimming macroinvertebrate predators were more abundant and the communities richer in species in the cold compared to the warm climate, most probably as a result of differences in fish predation pressure. Submerged plants in warm brackish lakes did not seem to counteract the effect of fish predation on macroinvertebrates to the same extent as in temperate freshwater lakes, since small fish were abundant and tended to aggregate within the macrophytes. The richness and abundance of most plant-associated macroinvertebrate taxa decreased with salinity. Despite the lower densities of plant-associated macroinvertebrates in the Mediterranean lakes, periphyton biomass was lower than in cold temperate systems, a fact that was mainly attributed to grazing and disturbance by fish. Our results suggest that, if the current process of warming entails higher chances of shallow lakes becoming warmer and more saline, climatic change may result in a decrease in macroinvertebrate species richness and abundance in shallow lakes.

Population dynamics of Triops cancriformis (Crustacea: Branchiopoda: Notostraca) of the Espolla temporary pond in the northeastern Iberian peninsula

The population dynamics of Triops cancriformis in Espolla temporary pond (NE Iberian peninsula) were studied during 1996 and 1997, which encompassed six flooded periods. Data were collected on each individuals size, sex, and, if female, on number of eggs in the oostegopodes. Male-biased sex ratios were found only in the drying-out phase and variations in fecundity were strongly related to hydroperiod duration. Sex ratio variation during the drying-out phase can be attributed to female mortality because the very low recruitment observed does not support the hypothesis of an increase of males. Two hypotheses are advanced to account for female mortality: (1) differential reproductive effort, and (2) size selective predation by herons. This population is characterised by low values of maximum densities compared with other notostracan populations, and by higher densities in the spring–summer hydroperiods than in the winter ones.

Comparative biodiversity of crustaceans and aquatic insects from various water body types in coastal Mediterranean wetlands

Coastal wetlands are characterized by a high biodiversity. At the same time, biodiversity is one of the main criteria used to establish protection policy priorities, or to propose management actions. In this study, crustacean and aquatic insect species richness in the Emporda wetlands was investigated. These two groups contribute in an important way to the total biodiversity, and still they are seldom taken into account in the management of natural areas. Representative samples (38 points) of all aquatic water body types in the Emporda wetlands were taken monthly (dip net with 250 μm mesh). Sampling was carried out between 1996 and 2000, but until present, only qualitative data have been extracted. A rich fauna of 125 crustacean taxa and 295 aquatic insect taxa were found. Some environments were characterized by low richness and high singularity (isolated artesian freshwater springs), some by high richness and high singularity (estuarine waters, brackish and meso-eutrophic freshwater wetlands), and others by low richness and low singularity (hypertrophic freshwater wetlands and hyperhaline wetlands). Factors determining singularity and richness are discussed. Comparison with crustacean richness of other western Mediterranean wetlands showed a similar high species richness in our study sites, probably due to high spatial heterogeneity of these areas.

Functional and Phylogenetic Relatedness in Temporary Wetland Invertebrates: Current Macroecological Patterns and Implications for Future Climatic Change Scenarios

In freshwater ecosystems, species compositions are known to be determined hierarchically by large to small‑scale environmental factors, based on the biological traits of the organisms. However, in ephemeral habitats this heuristic framework remains largely untested. Although temporary wetland faunas are constrained by a local filter (i.e., desiccation), we propose its magnitude may still depend on large-scale climate characteristics. If this is true, climate should be related to the degree of functional and taxonomic relatedness of invertebrate communities inhabiting seasonal wetlands. We tested this hypothesis in two ways. First, based on 52 biological traits for invertebrates, we conducted a case study to explore functional trends among temperate seasonal wetlands differing in the harshness (i.e., dryness) of their dry season. After finding evidence of trait filtering, we addressed whether it could be generalized across a broader climatic scale. To this end, a meta-analysis (225 seasonal wetlands spread across broad climatic categories: Arid, Temperate, and Cold) allowed us to identify whether an equivalent climate-dependent pattern of trait richness was consistent between the Nearctic and the Western Palearctic. Functional overlap of invertebrates increased from mild (i.e., Temperate) to harsher climates (i.e., Arid and Cold), and phylogenetic clustering (using taxonomy as a surrogate) was highest in Arid and lowest in Temperate wetlands. We show that, (i) as has been described in streams, higher relatedness than would be expected by chance is generally observed in seasonal wetland invertebrate communities; and (ii) this relatedness is not constant but climate-dependent, with the climate under which a given seasonal wetland is located determining the functional overlap and the phylogenetic clustering of the community. Finally, using a space-for-time substitution approach we suggest our results may anticipate how the invertebrate biodiversity embedded in these vulnerable and often overlooked ecosystems will be affected by long-term climate change.