Integrated treatment of farm effluents in New Zealand’s dairy operations

Maintaining growth through intensification in the New Zealand dairy industry is a challenge for various reasons, in particular sustainably managing the large volumes of effluent. Dairy farm effluents have traditionally been treated using two-pond systems that are effective in the removal of carbon and suspended solids, however limited in their ability to remove nutrients. In the past these nutrient-rich two-pond treated effluents were disposed of in surface waters. Current environmental concerns associated with the direct discharge of these effluents to surface waters has prompted in developing technologies to either minimise the nutrient content of the effluent or apply effluents to land. Here, we discuss various approaches and methods of treatment that enable producers to sustainably manage farm effluents, including advanced pond treatment systems, stripping techniques to reduce nutrient concentration, land application strategies involving nutrient budgeting models to minimise environmental degradation and enhance fodder quality. We also discuss alternative uses of farm effluents to produce energy and animal feed.     

Hypersaline waters in salterns - natural ecological niches for halophilic black yeasts

Hypersaline waters in salterns have so far been considered to be populated only with halophilic algae and bacteria and completely lacking halophilic fungi. In this paper we present population dynamics of polymorphic black yeasts, isolated from hypersaline waters (3-30% NaCl) of a saltern, in relation to different physicochemical parameters. Hortaea werneckii, Phaeotheca triangularis, Trimmatostroma salinum, Aureobasidium pullulans and Cladosporium spp. were detected with the highest frequency just before the peak of halite (NaCl) concentration. Since H. werneckii, P. triangularis and T. salinum are not known outside saline environments, these results suggest that hypersaline water is their natural ecological niche.     

Seasonal changes on two different spatial scales： response of aquatic invertebrates to water body and microhabitat

Knowledge about the spatial and temporal scales of both habitat use and the functional significance of different adaptations is essential for an understanding of the population dynamics of invertebrate assemblages. This fundamental knowledge is not only interesting from an academic point of view, but is sorely lacking and needed in the field of restoration ecology. Many species are threatened due to degradation. Knowing what environmental conditions are needed dtLring the life cycle of these species is important in the design of restoration measures which aim to lift existing bottlenecks for threatened species. To assess the relative importance of water type and microhabitat in structuring the invertebrate assemblage during different seasons, invertebrates were sampled in three water bodies differing in trophic level and acidity. Different parts within a water body （microhabitats） were sampled separately and each water body was sampled in all four seasons. Results show that water body is an important factor structuring the invertebrate assemblage early in the season, whereas microhabitat became more important later in the season. Structural complexity of microhabitats was related to the type of locomotion employed by invertebrates. Seasonal differences could be related to population dynamics （reproduction, mortality）. Moreover, fluctuations in resource availability were expected to differ between the water bodies, with highest fluctuations in the eutrophic water body and with fluctuations becoming less predictable later in the season. This was confirmed by the data： species synchronization to pulses in food availability was strongest in the eutrophic water body. Moreover, synchronization was strongest in summer, while in autumn waters were invaded by dispersive species. Based on these results a synthesis is presented on the functioning of the different waters during the different seasons.     

Limnological Features of Different Acidic Drinking Water Reservoirs in the Erzgebirge (Germany)

The biological and chemical investigations of three drinking water reservoirs differing in their acidic and trophic conditions (neutral/meso-eutrophic; circumneutral/oligotrophic; acid/oligomesotrophic) and of some of their tributaries in the Erzgebirge (Germany) are presented. It is shown that the chemistry of acidic waters is very different from circumneutral ones, particularly with respect to hardness, acid neutralizing capacity, pH and aluminium. As acidity in running and stagnant waters increases, the filtrable aluminium concentration also rises. A consequence of the changed chemical and biological conditions and their direct and indirect effects on the organisms is an overall decrease in the number of species (despite the fact that also some species newly appear in the acidified waters). Furthermore, a loss of food web complexity is observed and the trophic structure changes, e.g. fish have disappeared and invertebrate predators have become more numerous. In the acidic reservoir, species well adapted to waters low in pH and hardness (e.g. Synura sphagnicola) are more abundant and commonly benthic animals (e.g. Chydorus sphaericus) are able to extend their habitat to the open waters.     

Rapid recovery of benthic invertebrates downstream of hyperalkaline steel slag discharges

This study assesses the physical and chemical characteristics of hyperalkaline steel slag leachate from a former steelworks on two streams in England and their impacts on benthic invertebrate communities. Using multivariate methods (CCA), we related invertebrate richness and diversity with chemical parameters along the environmental gradient from point sources to less impacted sites downstream. Point discharges are characterised by high pH (10.6–11.5), high ionic strength (dominated by Ca–CO₃–OH waters), elevated trace elements (notably Li, Sr and V) and high rates of calcium carbonate precipitation. This combination of stressors gives rise to an impoverished benthic invertebrate community in source areas. The total abundance, taxonomic richness and densities of most observed organisms were strongly negatively correlated with water pH. Analysis using biological pollution monitoring indices (e.g. BMWP and Functional Feeding Groups) shows the system to be highly impacted at source, but when pH approaches values close to aquatic life standards, some 500 m downstream, complex biological communities become established. In addition to showing the rapid recovery of invertebrate communities downstream of the discharges, this study also provides a baseline characterisation of invertebrate communities at the extreme alkaline range of the pH spectrum.     

The beaver as an ecosystem engineer facilitates teal breeding

Positive interactions are important in influencing communities. Facilitation is one such influence in which a species makes the environment more suitable for others species. Ecological engineers are powerful facilitators as they physically modify habitats in a way that alters resource availability. We studied the effect of beaver flooding on breeding success of a dabbling duck, the teal. Our long-term (1988-2001) study was conducted in a boreal area where dabbling ducks face resource limitation. We focused on two aspects of facilitation: resource enhancement and habitat amelioration. We found that pond use by teal broods systematically increased upon beaver flooding. Beaver ponds harboured more resource, i.e. aquatic invertebrates than undisturbed waters, and invertebrate abundance was reflected as enhanced teal brood density. Beaver inundated shores were shallower than those of other waters, making their habitat structure more favourable to ducklings. Consequently, teal brood mortality was lower in beaver ponds than in waters unaffected by beaver. In boreal areas beaver facilitate teal breeding by enhancing both resource abundance and habitat structure.     

Effects of ship‐induced waves on littoral benthic invertebrates

1. Ship‐induced waves can affect the physical characteristics of lake and river shorelines, and laboratory studies have shown effects on littoral invertebrates. Here, we explored whether these effects could be observed under field conditions along a natural lake shore affected by wave sequences (trains) produced by boats. 2. Individuals of five invertebrate species (Bithynia tentaculata, Calopteryx splendens, Dikerogammarus villosus, Gammarus roeselii, Laccophilus hyalinus) were exposed to waves with increasing shear stress in five habitats differing in structural complexity. 3. Detachment of invertebrates increased with increasing shear stress and was best modelled using sigmoid response curves. Habitat structural complexity mitigated the effects of shear stress, and detachment rate was influenced more by habitat type than by species. A threshold (90% of the individual invertebrates unaffected) stress level of 0.64 N m^?2 was found for a structurally complex reed habitat, compared to 0.37 N m^?2 for a simple sand habitat. 4. Shear stress associated with wave trains created by recreational boating at a distance of 35 m from the shore and at a speed of 11 km h^?1 resulted in 45% detachment of littoral invertebrates. Decreasing the boat‐to‐shore distance to 20 m increased wave shear stress by 30% and invertebrate detachments up to 75%. 5. Disturbance of littoral habitats and invertebrate assemblages are widespread in inland waters used for recreational and/or commercial navigation. Our findings show that the integrity of littoral zones of navigable surface waters could be much improved by implementing management measures such as physically protecting complex habitats with dense reed belts and tree roots, and reducing boat speeds and increasing their minimum shoreline distance.     

Macrozoobenthos patterns along environmental gradients and hydrological connectivity of oxbow lakes

Hydrological connectivity and the frequency and intensity of floods are the key factors determining the structure of macroinvertebrates inhabiting wetland ecosystems in river valleys. In 2007, water and macroinvertebrate samples were collected on four occasions in the middle course of the S?upia River and in five oxbow lakes (Northern Poland) to determine the hydrological relations in a regulated lowland river environment marked by a moderate climate. The water bodies selected for the study featured different types of connections with the main river valley: two of them were completely cut off from the valley, one was connected via a single branch, one featured a forced-flow connection through drainage pipes, and one was connected by a system of drainage channels. Macroinvertebrates, mostly Chironomidae larvae, were predominant in the eutrophic waters of the river. The prevalent macroinvertebrates found in the eutrophicated oxbow lakes isolated from the river were Chironomidae larvae and Crustacea (mainly Asellus aquaticus). In unobstructed oxbow lakes, the main component of benthic fauna was Crustacea, while Ephemeroptera were found mostly in the water body connected to the river via a drainage channel. A canonical correspondence analysis (CCA) showed that hydrological connectivity was the main factor responsible for the structure of invertebrate populations, followed by the physical and chemical parameters of the local environment. A non-conformance analysis revealed that hydrological connectivity enhanced invertebrate abundance and biological diversity, while the overall abundance was marked by unimodal distribution. The developed general model indicates that in the group of measured environmental variables, nitrite concentrations were highly correlated with Shannon diversity and invertebrate composition, while sulphate levels were closely associated with invertebrate abundance in the waters of the analyzed ecosystems.     

Diet composition of larval Leiostomus xanthurus in and about the Mississippi River plume

The diet of the larvae of the sciaenid fish Leiostomus xanthuruscollected within the Mississippi River plume differs from thatof larvae collected in adjacent Gulf of Mexico shelf waters.Larvae collected in plume water had eaten twice as many foodorganisms as had larvae collected in shelf waters. Larvae collectedwithin the plume had eaten mostly small food organisms (tintinnids,copepod nauplii, pelecypod veligers and invertebrate eggs),whereas larvae collected in shelf waters had eaten mostly largerfood items (copepodite and adult copepods). Differences in theabundance of food organisms in and differences in the photicenvironments of these water masses may account for the differencesin diet.     

Copenhagen 1996-Variation in physical, chemical and biological components in the subantarctic lakes of South Georgia

Physical, chemical and biological variables were quantified in 19 subantarctic lakes (South Georgia) as a prelude to comparing these pristine systems with temperate lakes and to improve the knowledge of spatial and temporal variation in water chemistry and abundances of organisms. Lakes close to the sea had higher phosphorus concentrations, contained higher abundances of most organisms, and had higher number of invertebrate species than lakes situated further from the sea. Differences were attributed to higher nutrient input from marine organisms, such as penguins, seals and petrels, and probably also to a somewhat longer ice-free period. Since the lakes of South Georgia lack fish, the pelagic invertebrate fauna is dominated by herbivorous macrozooplankton. Rotifers are rare in the open water and are restricted to the vegetation (mainly mosses) in shallow areas and to the sediment surface. Generally, the algal abundance at the sediment surface is high in subantarctic lakes, indicating that the main part of the primary production is provided by benthic algae, which is in contrast to what is normally the case in temperate waters.     

Individual and combined effects of fish predation and bed disturbance on stream benthic communities: a streamside channel experiment

1. The composition and spatiotemporal dynamics of biological communities are influenced by biotic processes, such as predation and competition, but also by physical disturbances, such as floods in running waters. However, the interplay of disturbance with predation is still poorly understood, especially in frequently disturbed streams. Further, different predator species can affect prey communities in different ways depending on their feeding mode and efficiency. 2. We investigated the individual and combined effects of flood‐induced bed disturbance and fish predation on the benthos for 4 weeks in 18 streamside channels fed by a flood‐prone New Zealand river. Bed movements caused by floods were simulated by tumbling the substratum in half the channels. Six channels each were stocked with introduced brown trout (Salmo trutta) or native upland bully (Gobiomorphus breviceps) or had fish excluded. We studied algal biomass and both invertebrate density and daytime activity on surface stones on several dates after the disturbance, invertebrate community composition in the substrata of the entire channels on day 28 and leaf decomposition rates over the 28‐day period. 3. Disturbance affected algal biomass and density, richness and activity of surface stone invertebrates, and overall density and richness of channel invertebrates. Presence or absence of fish, by contrast, did not influence overall invertebrate standing stocks when subsurface substrata were included but did affect invertebrate densities on surface stones in 45% of all analysed cases and invertebrate activity on surface stones in all cases. Leaf decomposition rates were not influenced at all by the experimental manipulations. 4. Native upland bullies featured more often than exotic brown trout in causing invertebrate density changes and equally often in causing changes to grazer behaviour. Overall, our results imply that fish predation can have strong effects on the benthic invertebrate community in frequently disturbed streams, especially via behavioural changes.     

Macrophyte loss drives decadal change in benthic invertebrates in peatland drainage ditches

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Latitudinal and depth zonation of early Ordovician graptolites

Early Ordovician graptolites are inferred to have lived in two primary depth zones of the ocean waters. A shallow, epipelagic zone biotope contained species found preserved in all depth facies, whereas a deep, mesopelagic, zone biotope contained species now found only in deep-water facies (isograptid biofacies). An inshore biotope contained a few species that were apparently restricted to shelf-platform waters and which are now found in shelf sediments, along with members of the epipelagic biotope (didymograptid biofacies). The effects of surface water temperature on graptolite distribution, as measured by differences between high palaeolatitude (Europe/S. Britain - 'Atlantic province') and low palaeolatitude (Australasia/N. America-'Pacific province') regions, was less marked than that of depth. A survey of over 80 species and species groups shows that a surprisingly large number of graptolites were pandemic and eurythermic. In the early Ordovician, individual species were more widespread than those of any other invertebrate group, hence their great value for long-distance correlation. Biotopes, early Ordovician, depth facies, graptolite provinces, palaeolatitude.     

Tundra ponds of the Yukon Delta,Alaska, and their macroinvertebrate communities

The Yukon Delta, a low alluvial tundra in western Alaska, has more than 10⁵ thaw-basin ponds within its 70000 km² area. In 1984 and 1985, 68 ponds in three interior areas of the Delta were surveyed to determine limnological features, macroinvertebrate fauna, and trophic character. Ponds ranged up to 90 ha in area, 2 m in depth, and 17 m in elevation, and occurred in various temporal stages of growth and senescence. Among the 18 major invertebrate taxa collected, in order of decreasing frequency of occurrence, Trichoptera, Hemiptera, Diptera, Pelecypoda, Isopoda, Coleoptera, Gastropoda, and Oligochaeta were found in over 50% of the ponds. Trichoptera, the only taxon occurring in all ponds, was represented by 22 species of 6 families. The average Delta pond had 6.6 of the nine more common taxa. This measure of faunal richness was similar among study areas but was higher in low-tundra (sea level) ponds and in older ponds on raised tundra. In comparison, lentic invertebrate communities in five other areas of Alaskan and Canadian tundra had fewer taxa and also lower average richness based on occurrence of the same nine taxa.     

Chemical characteristics of pond waters in the Labyrinth of southern Victoria Land,Antarctica

A large number of fresh water and saline ponds are located in the Labyrinth (77° 33 S, 160° 50 E) of the upper Wright Valley in the Dry Valleys region of southern Victoria Land, Antarctica. It is situated near the terminus of the Wright Upper Glacier between 800–1000 m above sea level. From a limnological point of view, the most interesting problems concerning these saline ponds are the origin of their salts and their evolutional history.Chloride ion contents vary remarkably among the ponds ranging from 0.0049 to 52.4 g kg^–1. Surprisingly, more than a half of the ponds are saline with the highest chloride ion content being 2.7 times greater than that of seawater. The D and ¹⁸O values of the pond waters indicate a snow and/or glacial meltwaters origin, and that the ponds underwent subsequent alteration due to evaporation or freezing. The composition of chemical components reveal no evidence of trapped seawater. Thus the salt concentrations in the Labyrinth pond waters must be explained principally by the accumulation of atmospheric salts and subsequent repeated cycles of evaporation and freezing of the pond waters over considerable time periods.     

Selecting flagships for invertebrate conservation

Invertebrates have a low public profile and are seriously underrepresented in global conservation efforts. The promotion of flagship species is one way to generate interest in invertebrate conservation. Butterflies are frequently labeled invertebrate flagships, but clear definitions of the conservation actions they are meant to catalyze, and empirical assessments of their popularity amongst non-Western audiences are lacking. To improve the use of invertebrate flagships, we examine how butterflies compare with other taxa in terms of popularity. We then identify characteristics of individual species that are appealing and explore whether these may be used to derive a set of guidelines for selecting invertebrate flagships. We conducted questionnaire-based surveys amongst two target audiences: rural residents (n = 255) and tourists (n = 105) in northeast India. Invertebrates that were aesthetically appealing, or those that provided material benefits or ecological services were liked. Butterflies were the most popular group for both audiences, followed by dragonflies, honeybees and earthworms. A combination of large size and bright colours led to high popularity of individual species, whilst butterflies with unique features were liked by tourists but not rural residents. These results provide empirical evidence that butterflies appeal to diverse audiences and have the potential to be deployed as flagships in different contexts. However, prior to promoting invertebrate flagships, their intended uses need to be specified. Here we define an invertebrate flagship as an invertebrate species or group that resonates with a target audience and stimulates awareness, funding, research and policy support for the conservation of invertebrate diversity. In conclusion we outline a set of heuristic guidelines for selecting flagships to raise awareness of invertebrate diversity and conservation.     

APPLIED ISSUES Increasing litter retention in moorland streams: ecological and management aspects of a field experiment

1. The retention characteristics of two moorland streams in mid-Wales were manipulated for 2 years by the addition of small traps which accumulated detritus. Leaf litter was also added to these essentially treeless streams at regular intervals to simulate natural inputs to a woodland stream. 2. Leaf traps retained a significantly higher biomass of detritus - both naturally occurring and added - than either the surrounding stream bed or unmanipulated reference sections. They also supported significantly higher numbers of nemourid, leuctrid, tipulid and elminthid insect larvae. 3. Among functional feeding groups, detritivores and, to a lesser extent, predators responded to increased detritus availability. Numbers of mayfly larvae were low in leaf packs, suggesting a negative effect of detritus aggregations on their numbers. 4. The taxa which responded positively to increased detrital biomass, particularly stonefly larvae, are known to be tolerant of low pH conditions, whereas those affected detrimentally are generally absent from acid waters. It is proposed therefore that increasing detrital inputs and litter retention in culturally acidified upland streams may serve to increase their invertebrate productivity.     

Management strategies for sustainable invertebrate fisheries in coastal ecosystems of Galicia (NW Spain)

Artisanal coastal invertebrate fisheries in Galicia are socio-economically important and ecologically relevant. Their management, however, has been based on models of fish population dynamics appropriate for highly mobile demersal or pelagic resources and for industrial fisheries. These management systems focus on regulating fishing effort, but in coastal ecosystems activities that change or destruct key habitats may have a greater effect on population abundance than does fishing mortality. The Golfo Artabro was analysed as a representative example of a coastal ecosystem in Galicia, and the spider crab Maja squinado used as a model of an exploited coastal invertebrate, for which shallow coastal areas are key habitats for juvenile stages. The commercial legal gillnet fishery for the spider crab harvests adults during their reproductive migrations to deep waters and in their wintering habitats. Illegal fisheries operate in shallow waters. The annual rate of exploitation is >90%, and <10% of the primiparous females reproduce effectively at least once. A simple spatially-explicit cohort model was constructed to simulate the population dynamics of spider crab females. Yield- and egg-per-recruit analyses corresponding to different exploitation regimes were performed to compare management policies directed to control the fishing effort or to protect key habitats. It was found that the protection of juvenile habitats could allow increases in yield and reproductive effort higher than in the present system, with such protection based in the control of the fishing effort of the legal fishery. Additionally, there is an urgent need for alternative research and management strategies in artisanal coastal fisheries based on the implementation of a system of territorial use rights for fishers, the integration of the fishers into assessment and management processes, and the protection of key habitats (marine reserves) as a basic tool for the regulation of the fisheries.     

Beaver‐created successional gradients increase β‐diversity of invertebrates by turnover in stream‐wetland complexes

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