Search

DNA can be preserved in marine and freshwater sediments both in bulk sediment and in intact, viable resting stages. Here, we assess the potential for combined use of ancient, environmental, DNA and timeseries of resurrected long-term dormant organisms, to reconstruct trophic interactions and evolutionary adaptation to changing environments. These new methods, coupled with independent evidence of biotic and abiotic forcing factors, can provide a holistic view of past ecosystems beyond that offered by standard palaeoecology, help us assess implications of ecological and molecular change for contemporary ecosystem functioning and services, and improve our ability to predict adaptation to environmental stress., Ellegaard et al. discuss the potential for using ancient environmental DNA (eDNA), combined with resurrection ecology, to analyse trophic interactions and evolutionary adaptation to changing environments. Their Review suggests that these techniques will improve our ability to predict genetic and phenotypic adaptation to environmental stress.

Zooplankton in temporary ponds is often collected with gear originally designed for lakes, and mostly unsuitable for sampling shallow habitats. We describe a new simple and inexpensive device for sampling zooplankton in very shallow, vegetated temporary ponds. We tested the sampling efficiency by comparing species composition and density of cyclopoid copepods, an important component of the zooplankton, by sampling with both the new bag sampler and a plastic beaker frequently employed for collections of zooplankton in small waterbodies. With the bag sampler we collected a larger number of species and higher densities of copepods due to its higher efficiency in vegetated areas and near the sediment. The beaker appeared to sample almost only the water surface. The samples collected with the bag sampler revealed a distinct distribution of copepod life cycle stages in a shallow pond, which differed between depths and microhabitats. Additional advantages of the bag sampler are its small size and weight, and the possibility of fast exchange of sample bags between sample locations, thus preventing accidental faunal exchange between sample locations. We conclude that the bag sampler is a device especially useful for sampling zooplankton of shallow ponds and wetlands rich in vegetation, for diversity studies as well as for quantitative sampling. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

1. The survival of cyclopoid copepods was investigated in a floodplain for 2 years where flooding occurred during the cold season. The cyclopoid community was studied in three waterbodies with distinct hydroperiods: a permanent pond connected to the flooded area during inundation, a temporary pool that is part of the flooded area and an isolated temporary pool. 2. Field studies, including data obtained from samples of water, sediment and soil, showed the overall predominance of species with a summer diapause over those with a winter diapause or without diapause. Emergence of cyclopoid copepods at the onset of flooding, examined using emergence traps and data from recently filled or still isolated temporary pools, showed that some species can survive several months of drying. 3. The ability of the diapausing fourth copepodid stages of Cyclops strenuus and C. insignis, the two cyclopoids most abundant during winter and spring flooding, to survive terrestrial conditions was tested in laboratory experiments. Both species survived for several months, but rates differed among the species. A higher percentage of C. strenuus survived for a longer period, possibly explaining why this species was relatively more abundant in more temporary habitats. 4. Both dormancy and dispersal facilitated survival of cyclopoid copepods in transient habitats connected to each other during flood periods. Dormancy was the most important survival strategy, whereas dispersal could be more important following prolonged periods without flooding.

Over 30 years after drainage for agricul- ture, a 2700 ha temporary marshland was recently restored in Don˜ ana National Park. We describe the recovery of zooplankton communities (copepods, cladocerans and rotifers) in 47 new temporary ponds excavated as part of the restoration project during the first two hydroperiods (April 2006 and 2007), and compare them to those of eight reference sites in the surrounding marshland. Major changes in the species composition and abundance occurred in new ponds between years. While rotifers and cyclopoid cope- pods dominated in terms of number of individuals in 2006, calanoid copepods and cladocerans were the most abundant groups in 2007. Rotifer species richness was significantly lower in 2007, but there was an increase in Simpson and b-diversity in 2007 owing largely to a dramatic decline in the abundance of Hexarthra cf. fennica (rare in reference sites) from 93% of all rotifer individuals in new ponds in 2006 to only 32% in 2007. In contrast, species richness of copepods and cladocerans was significantly higher in new ponds in 2007, but there were no changes in Simpson diversity. b-Diversity of cladocerans was also significantly higher in 2007. In 2006, the species richness of cladocera and copepods was significantly lower in new ponds than in reference sites, but by 2007 there were no differences in richness or Simpson diversity. Overall, 7 copepod, 13 cladoceran and 26 rotifer taxa were recorded in new ponds, including 80% of taxa recorded in reference sites. These results indicate that zooplankton communities can be rapidly restored in Mediterranean temporary wetlands, at least when large source populations in the surrounding area reduce dispersal limitation. They also illustrate the importance of comparing different metrics of richness and diversity in studies of zooplankton restoration.

The viable propagule banks of a tempo- rary stream were studied from sections with different agricultural history. Hatching of zooplankton (cope- pods, rotifers and cladocerans) was recorded in the laboratory under controlled temperature and light conditions from an agriculturally modified area with average hydroperiods of about a week per year and two semi-natural reference areas with average hyd- roperiods of more than 3 weeks per year. We found significant differences in both taxon richness and abundance of zooplankton hatching between areas, which were lower in the agriculturally modified section, compared to the reference sections. Another factor likely to have influenced hatching in our experiment was conductivity, which differed between the two reference sections and might have affected hatching at high conductivities. For restora- tion purposes, hydrological reconnection of stream segments is important to facilitate dispersal from the high diversity upstream segments to the depleted sites downstream

The sequence in which new colonists reach an empty habitat can be crucial for future development and species structure of communities. It is therefore important to assess species composition and abundance in the initial stages of habitat existence. In the present study we focussed on colonization of newly constructed temporary ponds in Doñana, Southwest Spain, created by removing 30 or 60 cm of top soil. To confirm that no egg-bank was present, we conducted hatching experiments using sediment cores from six new ponds and two reference sites. Hatching was not recorded in the sediment of the new ponds with the exception of two rotifer individuals. In contrast, in the reference sites a maximum of 103 individuals per sample hatched, including cyclopoids, cladocerans, ostracods and rotifers. In the field, water samples were collected from seven ponds after 19 days of their first hydroperiod. Cyclopoid copepods, mostly Metacyclops minutus, had arrived and dominated all sampled ponds. Other taxa were the monogonont rotifer Brachionus plicatilis in four ponds, and the cladoceran Moina brachiata in one pond. The abundance of zooplankton was negatively correlated with conductivity, suggesting that ponds with higher conductivity undergo delayed colonization. We suggest that fast dispersal and dominance of certain cyclopoid copepods during early colonization is related to their ability to store sperm and fast individual development. Given that cyclopoid copepods can survive drought periods in the sediment of temporary ponds, first and early colonization by cyclopoids is likely to have a profound effect on the propagule bank and future plankton communities when the ponds refill.

Speculation about the role of waterbirds in the dispersal of aquatic invertebrates pre-dates Dar- win. However, there is a critical shortage of field studies quantifying such dispersal. We quantified the viability of aquatic invertebrates in the faeces of different waterfowl species collected in the field at different times during winter. Faeces were collected from four duck species (Northern Pintail Anas acuta, Mallard A. platyrhynchos, Shoveler A. clypeata, Eurasian Teal A. crecca) and Eurasian Coot Fulica atra in November 2004 and January 2005. We also collected soil samples from resting sites as an indicator of what may be transported on birds< feet and plumage. Faecal and soil samples were incubated using two treatments (0.4 and 4.0 mS cm–1) to quantify the potential for dispersal between aquatic habitats of different salinities. We found that viable Nematoda, Rotifera, Copepoda, Ostracoda, Insecta (Tipulidae), and Daphnia and Moina cladocerans were trans- ported internally by birds in the wild. We also found evidence that nematodes, rotifers, ostracods, cope- pods, tipulids, chironomids and hemipterans can be dispersed on birds< feet and feathers. The overall incidence of hatching from all samples was higher in January (59.4 %) than in November (11.5 %). With the exception of bdelloid rotifers, we found no evidence that the potential for dispersal between two habitats would be impeded by salinity in the range tested. Our data suggest that the taxonomic range of dispersed invertebrates and the frequency of their dispersal via waterfowl has previously been underestimated

Twenty-five sites located in five wetland zones within Donana, south-west Spain were studied for copepod and cladoceran species richness and composition in relation to habitat characteristics from January to March 2004. The c-diversity of copepods and cladocerans combined varied between wetland zones, which differed significantly in conductivity, surface area and abundance of vegetation. However, there were no significant differences between zones in local species richness of either copepods or cladocerans or the two combined. Species richness was significantly higher in sites with intermediate hydroperiods (duration between 3 and 5 months) than in sites with shorter or longer hydroperiods. CCA analyses performed separately for copepods and cladocerans extracted conductivity, surface area, and vegetation cover as the main factors structuring species composition of both groups. Ours is one of the first studies of zooplankton in the natural marshes of the Donana World Heritage Site, and we recorded five species new to the Donana area

The magnitude of community-wide dispersal is central to metacommunity models, yet dispersal is notoriously difficult to quantify in passive and cryptic dispersers such as many freshwater invertebrates. By overcoming the problem of quantifying dispersal rates, colonization rates into new habitats can provide a useful estimate of the magnitude of effective dispersal. Here we study the influence of spatial and local processes on colonization rates into new ponds that indicate differential dispersal limitation of major zooplankton taxa, with important implications for metacommunity dynamics. We identify regional and local factors that affect zooplankton colonization rates and spatial patterns in a large-scale experimental system. Our study differs from others in the unique setup of the experimental pond area by which we were able to test spatial and environmental variables at a large spatial scale. We quantified colonization rates separately for the Copepoda, Cladocera and Rotifera from samples collected over a period of 21 months in 48 newly constructed temporary ponds of 0.18–2.95 ha distributed in a restored wetland area of 2,700 ha in Don˜ ana National Park, Southern Spain. Species richness upon initial sampling of new ponds was about one third of that in reference ponds, although the rate of detection of new species from thereon were not significantly different, probably owing to high turnover in the dynamic, temporary reference ponds. Environmental heterogeneity had no detectable effect on colonization rates in new ponds. In contrast, connectivity, space (based on latitude and longitude) and surface area were key determinants of colonization rates for copepods and cladocerans. This suggests dispersal limitation in cladocerans and copepods, but not in rotifers, possibly due to differences in propagule size and abundance.