Status of aquatic and riparian biodiversity in artificial lake ecosystems with and without management for recreational fisheries: Implications for conservation

1. Humanity is facing a biodiversity crisis, with freshwater-associated biodiversity in a particularly dire state. Novel ecosystems created through human use of mineral resources, such as gravel pit lakes, can provide substitute habitats for the conservation of freshwater and riparian biodiversity. Many of these artificial ecosystems are subject to a high intensity of recreational use, however, which may limit their biodiversity potential.
2. The species richness of several taxa (plants, amphibians, dragonflies, damselflies, waterfowl, and songbirds) was assessed and a range of taxonomic biodiversity metrics were compared between gravel pit lakes managed for recreational fisheries (n = 16) and unmanaged reference lakes (n = 10), controlling for non-fishing-related environmental variation.
3. The average species richness of all the taxa examined was similar among lakes in both lake types and no substantial differences in species composition were found when examining the pooled species inventory. Similarly, there were no differences between lake types in the presence of rare species and in the Simpson diversity index across all of the taxa assessed.
4. Variation in species richness among lakes was correlated with woody habitat, lake morphology (surface area and steepness), and land use, but was not correlated with the presence of recreational fisheries. Thus, non-fishing-related environmental variables had stronger effects on local species presence than recreational fisheries management or the presence of recreational anglers.
5. Collectively, no evidence was found that anglers and recreational fisheries management constrain the development of aquatic and riparian biodiversity in gravel pit lakes in the study region; however, the conservation of species diversity in gravel pit lakes could benefit from an increasing reliance on habitat enhancement activities.

     

Whole‐community facilitation by beaver: ecosystem engineer increases waterbird diversity

1. Wetlands are rich in biodiversity, but globally threatened. After a long period of regional extirpation, beavers have recently returned to many European areas and are now restoring wetlands. The beaver is remarkable regarding the large impacts it has not only on individual species but on entire communities and ecosystems. In fact, beavers are referred to as ‘ecosystem engineers’.
2. The facilitative effect of the beaver Castor canadensis on a waterbird community of seven species of waders and ducks in boreal ponds was studied by using the before–after control–impact method (BACI) and analysing the effect of the duration of flooding. The before–after setting could be used since beavers had caused disturbance by flooding several forest ponds during the course of this long‐term study (1988–2009). The study took place in southern Finland, where waterbirds were surveyed four times during the breeding season.
3. The number of waterbird species per pond per year was significantly higher during beaver inundation than before beaver activity, as was the waterbird abundance per survey. Changes were negligible in the controls. The numbers of all seven species increased during flooding, although the increase was significant in only three species. Common teal Anas crecca and green sandpiper Tringa ochropus showed the most positive numerical response to flooding. Mallard Anas platyrhynchos and wigeon Anas penelope were new species entering the duck guild in the flooded wetlands. The beneficial effect of the flood lasted the whole period of inundation, although the most substantial increase in species number appeared during the first two years of flooding.
4. The beaver acted as a whole‐community facilitator for waterbirds. It was inferred from previous studies that this was done by modifying the habitat to make it more productive and structurally favourable. It is concluded that favouring beavers is a worthwhile tool in restoring wetlands to promote waterbird communities.

Copyright © 2014 John Wiley & Sons, Ltd.     

Biodiversity values of remnant freshwater floodplain lagoons in agricultural catchments: evidence for fish of the Wet Tropics bioregion,northern Australia

1. Tropical floodplain wetlands are among the world's most threatened and poorly documented freshwater ecosystems. This paper describes patterns of fish diversity in remnant freshwater lagoons in relation to natural environmental gradients and impacts of agriculture in the Tully–Murray catchment, Queensland Wet Tropics bioregion (QWT), in north‐eastern Australia.
2. Floodplain lagoons supported 21 of 29 native fish species recorded from freshwater habitats of these rivers, including three species not typically found in main river channels or tributaries, and six that require access to saline areas for spawning or larval development. Eight species favoured lagoons during their early life history, highlighting the vital role of these water bodies in providing nursery habitat.
3. Assemblage composition differed with distance from the coast, position on the floodplain, water quality and habitat. Aquatic vegetation discriminated lagoons and habitat patches within lagoons, and fish species richness was lower in patches of exotic ponded‐pasture grasses.
4. Although the lagoons are surrounded by intensive agriculture, especially sugarcane plantations, they are in good ecological condition, largely because of retention of some riparian vegetation, and frequent flushing by high stream flows. They offer opportunities to conserve taxonomic and functional biodiversity that is at present poorly protected by terrestrial reserves focused mainly on forested uplands. Of the 21 native species recorded, only one has >20% of its QWT distribution protected in IUCN category II protected areas (National Parks), and nine species have <10% of their QWT distribution in protected areas.
5. Opportunities to protect tropical freshwater fish diversity may be lost if threatening processes are not held in check through maintenance of natural flow regimes and floodplain connectivity, protection of riparian vegetation and aquatic habitat structure, continued application of best management farming practices and off‐reserve protection of freshwater habitats on public and private lands.

Copyright © 2014 John Wiley & Sons, Ltd.     

Application of macroinvertebrate multimetrics as a measure of the impact of anthropogenic modification of spring habitats

1. Springs are distinct freshwater habitats that are threatened globally by human impacts, but are not included in standard freshwater assessment tools. This study analysed how the standard macroinvertebrate metrics currently used in biomonitoring programmes for running waters perform in springs with similar ecological qualities but with a different degree of hydromorphological modification. Macroinvertebrate assemblages were analysed in 50 riparian springs along the Crvcka River in the Dinaric karst.
2. Most metrics analysed (ASPT, EPT_fam, PTH_fam, BMWP, STAR_ICMi, and Spring_ICMi) showed significant differences between hydromorphologically modified and natural, i.e. unmodified, springs.
3. A self‐organizing map (SOM), an unsupervised artificial neural network, was used for patterning and visualizing 10 environmental parameters and the metrics analysed. Most macroinvertebrate metrics, besides IBE (which did not show any pattern) and PTH_fam (which showed an opposite trend), had significantly lower values in the spring group with the highest electrical conductivity and the lowest discharge.
4. The study showed that hydromorphological modification does not necessarily lead to a loss of crenobiontic species, provided that the discharge and substrate composition remain suitable. Future coordinated conservation strategies must take into account the fact that spring species assemblages are sensitive to habitat structure and organic pollution, as has been achieved in Europe for rivers assessed under the Water Framework Directive.
5. Using multimetric indices, such as the new Spring_ICMi, may help to provide a framework for assessing the response of macroinvertebrate assemblages to human impacts. They may also help in assessing the success of measures used for the conservation and restoration of these threatened but highly valuable habitats. Further investigations should verify the suitability of such metrics in assessing the deterioration of springs globally.

     

The role of lateral connectivity in the maintenance of macrophyte diversity and production in large rivers

1. Large European river floodplains have been intensively reduced through human activities over several millennia. Ecological assessments of natural large river systems remain rare and potentially flawed since they typically omit either the main channel of the river or, more commonly, aquatic habitats that occur naturally in the floodplain of dynamic systems.
2. Surveys were conducted over a longitudinal and lateral gradient to assess distribution, richness and production of macrophytes along two little‐disturbed large upland rivers in Scotland.
3. Lateral dynamics, through the creation of backwaters, underpinned the occurrence, abundance and production of macrophytes in these rivers. Indeed, backwaters, despite representing only 5% of the total area of aquatic habitat, supported a significantly higher concentration of species (65% of species recorded at the riverscape scale were unique to backwaters) than the main channel.
4. The frequency with which backwaters were connected to the main channel during flood flows influenced their species richness. Highest species richness in backwaters was typically found at low connectivity. Standing crop in backwaters was 150 times higher per unit area than in the main channel, while at the riverscape scale backwaters accounted for an average 89% of aquatic plant biomass. The highest plant biomass was found at low and medium connectivity with the main channel.
5. Backwaters appear to be crucial habitats in maintaining macrophyte diversity and production in large river ecosystems. These results emphasize the importance of river hydrodynamics and lateral connectivity in maintaining macrophyte community diversity along large rivers. The results illustrate also the potentially very significant role of backwaters as source habitats supplying propagules and organic matter to downstream reaches.
6. It is argued that the entire riverscape (floodplain plus main channel) must be considered in the holistic assessment of such systems, while protection of this resource requires greater recognition of linkages within and across habitats, both aquatic and terrestrial, to be effective.

Copyright © 2012 John Wiley & Sons, Ltd.     

Conservation of threatened species in the Galapagos Marine Reserve through identification and protection of marine key biodiversity areas

• 1. The Galapagos Marine Reserve provides refuge for numerous threatened marine species, including 16 mammals, birds, reptiles and fish currently recognized on the 2006 IUCN Red List of Threatened Species, plus an additional 25 endemic fish, mollusc, crustacean, echinoderm, coral and macroalgal species that comply with threatened species criteria because of declining extent of occurrence or highly‐localized ranges, and hence also qualify for inclusion on the Red List.
• 2. Threatened marine species with restricted ranges are not randomly distributed across the archipelago but tend to co‐occur at a limited number of sites that are predominantly located in the west. Sites at which threatened species are known to persist, particularly those with a large proportion of the global population, are here identified as sites of global conservation significance — key biodiversity areas.
• 3. The majority (27) of the 38 inshore key biodiversity areas identified are currently protected from fishing because they lie within the 17% of coastal waters that is zoned as ‘no‐take’ tourism or conservation zones. All key biodiversity areas should be protected from extractive exploitation if threatened species are to be safeguarded. This can be achieved, at the minimum, through a relatively minor amendment to the existing marine zoning scheme, whereby an additional 2% of the coastline is dedicated to conservation.

Copyright © 2008 John Wiley & Sons, Ltd.     

Alien and endemic flora at reference and non‐reference sites in Mediterranean‐type streams in Portugal

• 1. A comparison was made between a variety of alien and endemic plant species from 272 aquatic and riparian habitats in Portuguese Mediterranean‐type streams in reference condition — i.e. near‐natural river corridors — and non‐reference condition. The objective was to detect differences in relative proportion and cover between these species groups. The differences in endemic and alien flora from siliceous and calcareous river types were also analysed. Environmental and human disturbance factors were related with the richness and cover of both species groups.
• 2. A total of 568 species were found, of which 44 were alien and 28 were endemic. Alien species were present at 91% of the surveyed locations, and were consistently more widespread at non‐reference sites than at reference ones for both river types, with calcareous sites having a higher invasibility. Endemic species occurred at 45% of the sampling sites and displayed a significantly lower richness and cover than their alien counterparts.
• 3. Alien richness and cover were positively related to direct human disturbance within the river systems, and with floodplain uses such as urban occupation, intensive agriculture, and nutrient inputs. Endemic species also respond to anthropogenic variables, rather than to climatic and geographical ones, with richness and cover increasing as human impacts on fluvial systems and related floodplains decrease.
• 4. Comprehensive control of alien invasive species and the protection of endemic plant populations will require attempts at monitoring ecological river integrity, and the achievement of ‘good ecological status’ — one of the goals of the European Union's Water Framework Directive. Portuguese riparian areas must be managed in such a way as to protect the relatively few preserved riparian habitats by lowering the direct and indirect pressures in fluvial corridors and thus preventing future alien plant invasions.

Copyright © 2006 John Wiley & Sons, Ltd.     

Niche specialization and functional traits regulate the rarity of charophytes in the Nordic countries

1. Charophytes are benthic macroalgae that live in fresh and brackish waters. Given the historic deterioration of their habitats and their competitive inferiority relative to tall rooted plants under eutrophic conditions, it is hypothesized that charophytes are among the most threatened autotrophs. Also, it is expected that charophytes with generalist niches and functional traits, such as tolerance of a broad salinity range and large height, should thrive owing to available habitats and stronger competitive ability.
2. These hypotheses were tested comparing the rarity of charophytes in the Nordic countries with other autotrophs and analysing the relationship to species niche specialization and functional traits. A value on a rarity–commonness scale was assigned to each species based on their Red List status. Niche specialization was evaluated by the Outlying Mean Index using a large Danish dataset while traits were derived from the literature.
3. Supporting the hypotheses, 50–87% of charophyte species were Red Listed, which is much greater than for vascular aquatic (30–35%) and terrestrial plants (18–28%). Commonness of charophytes decreased significantly with niche specialization in separate analyses of brackish and freshwater sites. For brackish water species, the most influential parameter determining species distribution was salinity while for freshwater species, alkalinity, lake size and chlorophyll concentration played a major role. Four functional traits: shoot height, salinity tolerance, bulbil production and flexible life cycle duration were significantly positively related to commonness.
4. In conclusion, charophytes contain a larger fraction of threatened species compared with other groups of autotrophs. The few common charophytes are generalists tolerant of a wide range of conditions, while specialists often have short stature, restricted life cycle variability and are rare in the disturbed contemporary landscape. It is thus a conservation priority to delineate accurately the environmental conditions preferred by the threatened species and protect or restore proper habitats.

Copyright © 2015 John Wiley & Sons, Ltd.     

A comparative analysis of habitat quality between artificial and natural creeks in the Mediterranean killifish Aphanius fasciatus: Implications for conservation

1. In transitional water ecosystems, habitat loss is one of the major threats to fish biodiversity. This is particularly true in the case of temperate salt marshes. Good quality artificial novel habitats may compensate for the loss of natural habitats, acting as a refuge for fish populations.
2. The aim of this study was to use coloured ornamental traits exhibited by the males of a small lagoon-resident fish, the Mediterranean killifish Aphanius fasciatus (Valenciennes, 1821), to assess habitat quality in both the natural and artificial creeks of the Venice lagoon.
3. The conspicuousness of two secondary sexual traits, the yellow/orange caudal fin pigmentation and the contrast between white and dark vertical bars on body sides, proved to be greater in artificial habitats compared to natural salt marshes, highlighting the refuge function of artificial creeks.
4. The use of secondary sexual traits could be extended to other fish species and to other aquatic habitats as a non-invasive approach. This would allow the identification of good quality habitats in the context of fish population management and conservation.