High Diversity Of Invertebrates Research Articles

Plant and invertebrate diversity in grassland field margins

This study investigates three treatment methods to establish field margins of high botanical and invertebrate diversity within an intensively managed grassland system. Field margin treatments were: fenced only, rotavated and allowed to regenerate naturally, reseeded with a grass and wildflower seed mixture. Control plots were unfenced and grazed. Field margin widths were established at 1.5, 2.5 and 3.5 m. The botanical composition of the plots was examined on four occasions between 2002 and 2004 using permanent nested quadrats. Emergence traps were installed in each of the treatments to investigate invertebrate abundance response to treatment. Results showed that (1) reseeding had a positive effect on resultant botanical diversity when compared with other establishment treatments investigated, (2) natural regeneration after rotavation could not be recommended as an effective means of restoring diversity under these environmental conditions, due to the abundance of undesirable weed species, (3) exclusion of fertiliser inputs alone resulted in a very slow change in the botanical composition, (4) width of plot did not have a significant influence on plant species richness and (5) treatment and time of sampling had highly significant impacts on overall invertebrate abundance.

Intensified grazing affects endemic plant and gastropod diversity in alpine grasslands of the Southern Carpathian mountains (Romania)

Alpine grasslands in the Southern Carpathian Mts, Romania, harbour an extraordinarily high diversity of plants and invertebrates, including Carpathic endemics. In the past decades, intensive sheep grazing has caused a dramatic decrease in biodiversity and even led to eroded soils at many places in the Carpathians. Because of limited food resources, sheep are increasingly forced to graze on steep slopes, which were formerly not grazed by livestock and are considered as local biodiversity hotspots. We examined species richness, abundance and number of endemic vascular plants and terrestrial gastropods on steep slopes that were either grazed by sheep or ungrazed by livestock in two areas of the Southern Carpathians. On calcareous soils in the Bucegi Mts, a total of 177 vascular plant and 19 gastropod species were recorded. Twelve plant species (6.8%) and three gastropod species (15.8%) were endemic to the Carpathians. Grazed sites had lower plant and gastropod species richness than ungrazed sites. Furthermore, grazed sites harboured fewer gastropod species endemic to the Carpathians than ungrazed sites. On acid soils in the Fagaras Mts, a total of 96 vascular plant and nine gastropod species were found. In this mountain area, however, grazed and ungrazed sites did not differ in species richness, abundance and number of endemic plant and gastropod species. Our findings confirm the high biodiversity of grasslands on steep slopes in the Southern Carpathian Mts and caution against increasing grazing pressure in these refuges for relic plants and gastropods as well as for other invertebrates.

Effects of abandonment of subalpine hay meadows on plant and invertebrate diversity in Transylvania, Romania

Recent changes in agriculture (intensification or abandonment) have resulted in a critical reduction of semi-natural grasslands in Eastern Europe. Subalpine semi-natural grasslands in Transylvania, Romania, harbour a high diversity of plants and invertebrates, including endemics, and are considered refugia for numerous threatened open-land species. We investigated effects of land abandonment by examining species richness, species abundance, proportion of open-land, endemic and threatened vascular plants, gastropods, and diurnal and nocturnal Lepidoptera in extensive hay meadows (initial stage), and three seral stages of succession (early stage of abandoned hay meadow, naturally growing birch forest, and mature forest) in the mountainous region of Baisoara in Transylvania. A total of 626 species (225 vascular plants, 16 gastropods, 68 diurnal and 317 nocturnal Lepidoptera) were found in the 16 study sites (four replicates per successional stage). The four taxonomic groups differed in their response to the abandonment of hay meadows. Each stage of succession harboured the maximum species richness for one taxonomic group: extensive hay meadows for vascular plants, abandoned hay meadows for diurnal Lepidoptera, birch forests for nocturnal Lepidoptera, and mature forests for gastropods. In all four taxonomic groups the complementarity of species composition increased with successional age, whereas the number of characteristic open-land species decreased with successional age. The four successional stages did not differ in proportion of red-listed plant and diurnal Lepidoptera species. In nocturnal Lepidoptera, however, the proportion of red-listed species increased with successional age. Furthermore, successional stages did not differ in number of plant species endemic to the Carpathians and Eastern Europe. Our results indicate the high conservation value of all stages of subalpine grassland succession for the indigenous biodiversity of Transylvania. To prevent losses of characteristic species, we suggest a rotational grassland management program that maintains different successional stages.

Salinization consequences in running waters: use of asentinel substrateas a bioassessment method

Salinization has been disturbing increasing numbers of inland waterways, and new analytical tools are needed to survey water quality and to assess the impact of salinization. Researchers have developed new protocols that reduce the number and type of samples required to reduce the cost of existing assessment methods. Our study contributes to this effort with the primary objective of identifying a single, unique river-bottom substrate that could be sampled to detect the impact of rising salinity on macroinvertebrate assemblages. We hoped to define a new concept of sentinel substrate, a substrate with an invertebrate assemblage that would signal an environmental impact (in this case increasing salinity) and that could be used at the site scale to assess that impact. We worked on the Meurthe River, which presents a significant salinity gradient (from 0.2 to 2.6 g/L) over a 19-km section of river in which all other physicochemical variables remain stable. We sampled substrates present at each of 4 sites along the salinity gradient in 2002 and described the effects of rising salinity on the structure (richness, diversity, and dominance) of the macroinvertebrate assemblage in each substrate type. Only the assemblage in pebbles adequately reflected site-level responses. Moreover, only assemblages in pebbles satisfied important criteria such as widespread availability, low variability among seasons, and high invertebrate diversity.

The Success of a Rotational Grazing System in Conserving the Diversity of Chalk Grassland Auchenorrhyncha

A complex rotational grazing trial on a south-facing slope of chalk grassland at the Old Winchester Hill National Nature Reserve is briefly introduced. The responses of 23 numerous species of Auchenorrhyncha, and of species richness (S) and total abundance (N), from 1981 to 1985 are described. The greatest effects were those of variation between years, between positions on the hillside (top, middle and bottom) and between grazing plots within these positions. 10 (of the total of 23) species favoured the top of the slope, where the vegetation was significantly taller than in the middle or at the bottom. S, N and the numbers of 8 species were significantly lower on plots grazed in the year of sampling compared with ungrazed plots. Early (vs. late) grazing significantly reduced S, N and the abundance of two species, but increased the numbers of Macrosteles laevis. S, N and the abundance of 13 species was significantly and positively correlated with vegetation height measured early (May–June) and late (July–October); the numbers of 4 other species were so correlated with the latter height only. The significance of the results is discussed in relation to the management of grassland nature reserves for the maintenance of high invertebrate diversity. It is concluded that rotational management is an important and valuable system, but suggested that such systems should be as simple as possible whilst remaining adequate to achieve conservation objectives.

Alterations of Steppe‐Like Grasslands in Eastern Europe: a Threat to Regional Biodiversity Hotspots

Abstract: Recent changes in agriculture (intensification or abandonment) have resulted in a critical reduction of steppe‐like grasslands in Eastern Europe. These grasslands harbor an extraordinarily high diversity of plants and invertebrates, including endemics, and are considered refugia for numerous threatened open‐land species. We examined species richness, and abundance, proportion of open‐land, endemic and threatened vascular plants, gastropods, and diurnal and nocturnal Lepidoptera in six different vegetation types all originating from steppe‐like grasslands in Transylvania, Romania. Vegetation types included extensively grazed pastures (initial stage), three seral stages of succession (early stage of abandoned grassland, abandoned grassland with shrubs, and mature forest), and two human‐made grassland alterations, namely abandoned vineyards and Pinus plantations. A total of 852 species (291 vascular plants, 24 gastropods, 129 diurnal and 408 nocturnal Lepidoptera) were found in the 22 study sites. The four taxonomic groups differed in their response to the abandonment of steppe‐like grassland, except that species richness of plants and diurnal Lepidoptera were positively correlated. The complementarity of species composition increased with successional age in all taxonomic groups examined. The number of characteristic open‐land species decreased with successional age in plants and gastropods. All investigated vegetation types harbored threatened (red‐listed) species. Endemic species were found in all vegetation types except mature forests and Pinus plantations. All Transylvanian endemics and the majority of threatened species found were open‐land species. Extensively cultivated vineyards, which have been abandoned for two to three decades, also maintained high plant and invertebrate diversities, comparable to those of the corresponding stages of grassland succession. In contrast, Pinus plantations (a recent grassland alteration) have changed habitat quality and will have a devastating effect on the unique, indigenous diversity of these steppe‐like grasslands as soon as the canopy closes. To prevent losses of characteristic species, we suggest a rotational grassland management program that maintains different seral stages. Succession to mature forest and additional Pinus plantations should be prevented.

Effects of boating activities on aquatic vegetation in the Stockholm archipelago, Baltic Sea

The aquatic vegetation in 44 similar shallow and sheltered inlets exposed to different kinds of disturbances by boating was studied in a rocky archipelago in the Baltic Sea. The results indicate that both recreational boating activities and traffic by medium sized ferryboats may cause significant changes in community composition and have significant negative effects on species richness and the development of the macrophytic vegetation at greater depth. Changes in inlet morphology by dredging and increases in resuspension and turbidity by wave-action from boats were most probably the major factors contributing to the demonstrated differences in the vegetation between inlets. In inlets used as harbours for private boats (marinas) or adjacent to ferryboat routes, vegetation cover and species richness declined significantly more with depth than in reference inlets not exposed to disturbance by boating activities. In marinas, turbidity was significantly higher than in reference inlets. Accordingly, a canonical correspondence analysis showed that the abundance of species sensitive to poor light conditions, such as Chara spp. and Ruppia spp. were negatively correlated with marinas while Myriophyllum spicatum and Ceratophyllum demersum that are common in nutrient rich turbid habitats were positively correlated with marinas. Mechanical disturbance by propellers may also have contributed to the results, disfavouring Potamogeton pectinatus compared to similar caulescent species in marinas. Chara tomentosa and Najas marina that are exposure sensitive mud thriving species were negatively correlated with inlets adjacent to ferryboat routes, while the macroalga Fucus vesiculosus that is dependent on clean substrate for successful recruitment was positively correlated with inlets adjacent to ferryboat routes. It is important to explore further the effects of boating activities in these habitat types, since the studied inlets sustain a high diversity of both plants and invertebrates and provide highly significant recruitment areas for coastal fish in the Baltic Sea.

Mysid crustaceans as potential test organisms for the evaluation of environmental endocrine disruption: a review.

Anthropogenic chemicals that disrupt the hormonal systems (endocrine disruptors) of wildlife species recently have become a widely investigated and politically charged issue. Invertebrates account for roughly 95% of all animals, yet surprisingly little effort has been made to understand their value in signaling potential environmental endocrine disruption. This omission largely can be attributed to the high diversity of invertebrates and the shortage of fundamental knowledge of their endocrine systems. Insects and crustaceans are exceptions and, as such, appear to be excellent candidates for evaluating the environmental consequences of chemically induced endocrine disruption. Mysid shrimp (Crustacea: Mysidacea) may serve as a viable surrogate for many crustaceans and have been put forward as suitable test organisms for the evaluation of endocrine disruption by several researchers and regulatory bodies (e.g., the U.S. Environmental Protection Agency). Despite the long-standing use of mysids in toxicity testing, little information exists on their endocrinology, and few studies have focused on the potential of these animals for evaluating the effects of hormone-disrupting compounds. Therefore, the question remains as to whether the current standardized mysid endpoints can be used or adapted to detect endocrine disruption, or if new procedures must be developed, specifically directed at evaluating hormone-regulated endpoints in these animals. This review summarizes the ecological importance of mysids in estuarine and marine ecosystems, their use in toxicity testing and environmental monitoring, and their endocrinology and important hormone-regulated processes to highlight their potential use in assessing environmental endocrine disruption.

Distribution of Cladoceran Zooplankton Among Prairie Pothole Wetlands in Northwest Iowa

ABSTRACT Cladoceran zooplankton were collected and identified from spring and summer samples from vegetated and open water areas of 26 remnant glacial lakes in Dickinson County, Iowa. The purpose of the study was to determine the factors influencing the structure and composition of zooplankton assemblages as a tool for aiding environmental management of the region's prairie pothole wetlands and ponds. The ponds were assorted into five categories based on morphometric features and productivity: ‘chain lakes’ defined large, deep, interconnected lakes; ‘algal potholes’ were small pothole wetlands dominated by algal primary producers; ‘weedy potholes’ denoted similar ponds dominated by macrophytic vegetation; ‘sloughs’ were similarly dominated by macrophytes, but found along intermittent waterways subject to drying; and ‘walleye ponds’ were kettle-hole ponds modified for the production of gamefish. Multivariate analyses and similarity indices were used to determine the relationship between cladoceran assemblages and the five major lake types. Each lake type contained a distinct cladoceran assemblage that was influenced by the abundance of macrophytes and probably also by fish, although fish species composition was not directly measured. Cladoceran diversity also increased with increased predominance of macrophytes among lakes, and within the same lake in different seasons and sampling locations. A model was built to describe the relationship between cladoceran assemblages and macrophytes that could be used in management or paleoecological applications. If prairie potholes are to be managed for high invertebrate diversity to support waterfowl, our results promote plans that diversify benthic structure within ponds. Advanced eutrophication and conversion of existing potholes to game fish rearing ponds severely limit the abundance and composition of microcrustaceans, which is likely to alter upper levels of the food web.

Secondary succession, soil formation and development of a diverse community of oribatids and saprophagous soil macro-invertebrates

Investigations into different stages of secondary succession (from a wheat field to a beechwood on Threstone; Northern Germany) demonstrated the formation of a carbon rich top soil in later successional stages. Parallel to changes in plant species and soil formation, there were also changes in species composition and diversity of saprophagous macro-invertebrates (Lumbricidae, Diplopoda, Isopoda) and oribatid mites (Acari: Oribatida). Diversity of diplopod and isopod species increased after cessation of cultivation, but in a late successional stage (ca 50 y-old fallow, ash-dominated wood) species number of diplopods and isopods declined strongly. In comparison with the other soil invertebrate groups, species composition of earthworms among the sites was more similar. Accumulation of soil C was assumed to be related to wood formation and occurrence of woody debris and recalcitrant leaf litter of beech trees. Incorporation of recalcitrant litter materials by earthworm species living in the upper mineral soil presumably contributed significantly to accumulation of soil C. Accumulation of soil C was accompanied by the development of an oribatid mite community rich in species. In early successional stages oribatids predominantly colonized the litter layer, while most oribatid mites of the beechwood inhabited the upper mineral soil. Maximum diversity of oribatid mites in the beechwood is assumed to be related to instability of the mineral soil caused by earthworm activity. Changes in species composition and diversity are discussed considering succession theory. Even soil invertebrates of similar trophic groups appear to respond very differently to successional changes. It is concluded that conservation strategies to maintain high diversity of soil invertebrates are most likely to be successful if a wide range of habitats of different successional stages is included.

The Littoral Station of Aguda, in the North of Portugal

The public authorities have recently approved the building of a Littoral Station in Aguda, a small fishing village on the Atlantic coast, 15 km south of the River Douro estuary in the municipal area of Vila Nova de Gaia. The internal structure of the building involves a Fishery Museum exhibiting ancient and modern gear, a Public Aquarium displaying the local marine fauna and flora and a Research and Educational Department for marine biology, aquaculture and fishery. The project was drawn up by the architect Joao Paulo Peixoto, in collaboration with local engineers, and the author. In Aguda there is an active, small-scale fishery, based on traditional methods handed down from generation to generation. The almost unstudied local marine fauna and flora is characterized by a high diversity of invertebrates and a rich abundance of fish stocks. Easy access to a variety of marine biotopes is guaranteed by means of the local fishing-fleet, thus supporting the Station's programme of education and research.

Biodiversity of Coral Reefs: What are We Losing and Why?

SYNOPSIS. Coral reefs are threatened by numerous anthropogenic impacts, some of which have already had major effects worldwide. These unique tropical environments harbor a high diversity of corals, reef invertebrates, fish and other animals and plants. In most taxa, the species diversity of reef-associated organisms is poorly understood because many of the species have yet to be collected and described. High coral mortality has been associated with natural events such as hurricanes, predator outbreaks and periods of high temperature, but has also resulted from excess nutrients in sewage and from specific pollutants. Reef corals and associated organisms are also threatened by the possibility of global warming which will result in rising sea levels and periods of increased temperature stress, and which may also bring increased storm frequency and intensity. Although the recent extensive episodes of coral bleaching in the Caribbean and eastern Pacific cannot be causally related to global warming at this time, the close link between bleaching and temperature suggests that global warming will result in severe changes in coral assemblages. Major reef destruction has followed outbreaks of the predatory seastar Acanthaster planci in the Pacific. Although this is considered part of a natural disturbance cycle, there are indications that altered land use patterns and reduction of predators on this seastar by human activities may have increased the severity of outbreaks. Recreational and commercial use of reefs has also increased, and has caused extensive damage, especially near areas of high population density. One of the most obvious and widespread losses to reef biota is the reduction in fish populations from intense overfishing in most reef areas of the world. Coasts without adequately managed reefs have suffered intense overfishing for both local and export purposes, to the point where the positive effects of fish on those reefs have been compromised. The combination of these destructive factors has altered reefs in all localities, and many that were once considered protected by distance and low population density are now being exploited as well. On the positive side, improved understanding of ecological processes on reefs combined with concerted conservation efforts have managed to protect some extensive areas of reef for the future.

Nektonic invertebrate abundance and distribution at the emergent vegetation-open water interface in the Delta Marsh, Manitoba, Canada

The emergent vegetation-open water interface plays an important role in the use of freshwater wetlands by many species of animals. The objective of this study was to monitor the distribution and abundance of free-swimming invertebrates at the cattail (Typha × glauca Godr.)—open water interface in two bays (sheltered and unsheltered) in the Delta Marsh in south-central Manitoba during 1985. Submersed vegetation densities were higher in the open water sites of the sheltered bay during most of the summer. Water temperatures were constant across the interface through much of the year. By mid-summer, hypoxic conditions prevailed within the water column in the cattail stand. Algae levels were similar across the interface throughout much of the year, with peaks occurring just inside the interface in June and July. Early in the season, there was a trend for higher nektonic invertebrate numbers within the cattail stands of both bays. By late August, there were similar total invertebrate numbers across the interface. Cladocera and ostracod numbers were higher within the cattail stands during June and July; during the same periods, corixid levels were higher in the open water sites. The low oxygen levels within the cattail stands during the summar may reduce predation by fish and other predators that cannot tolerate low oxygen levels. This may explain the higher numbers of prey species like cladocerans and ostracods within the cattail stands during mid-summer. The presence of algal or detrital food resources seemed to have little influence on invertebrate abundance across the interface during this study. Peaks in invertebrate abundance did not occur at the emergent vegetation-open water interface during any of the sampling periods in this study. The high invertebrate diversity and abundance in interspersed wetland habitat may be related more to the mixture of habitat types rather than the amount of interface present.

Diet of the Squirrel Glider, Petaurus norfolcensis (Marsupialia: Petauridae), in Victoria.

Analysis of faecal pellets from Petaurus norfolcensis in northern and central Victoria showed that it ate insects, principally Coleoptera and lepidopteran larvae obtained from the foliage of Eucalyptus and Acacia, and plant exudates, especially Eucalyptus sap and Acacia gum. Diet was broadly similar to that of its congeners P. australis and P. breviceps but differed in the ubiquitous presence of insect remains, the preponderance of caterpillars (particularly the noxious Doratifera sp.) and the relative insignificance of spiders. Eucalyptus nectar and pollen, as well as lerps, which are important to other Petaurus spp. elsewhere, appeared to be less important components of the diet of P. norfolcensis at our main study site. This result was probably due to these food items being unavailable when we collected the pellets. The items were heavily utilised at another site. The availability of pollen and nectar may be irregular and unpredictable in eucalypt open forests of low species diversity. Absence of this rich source of protein and nitrogen may be partially compensated for by the relatively high diversity and density of foliage invertebrates.

Quantification of Wood Habitat in Subtropical Coastal Plain Streams

To assess the importance of woody debris in two relatively unaltered Coastal Plain streams in the southeastern United States, a line intersect technique, developed by foresters, was used to estimate volume, mass, surface area, and spatial distribution. The ash-free dry mass of in-channei woody material was 6.5 kg/m2 of stream channel bottom in the sixth-order Ogeechee River and 5.0 kg/m2 in the fourth-order Black Creek. Most wood is located near the erosional bank in these meandering streams. These wood mass estimates are much higher than expected for middle-order streams and are similar to those from several small headwater streams in other regions. Due to their very low slopes (<0.02%), these streams appear to have insufficient stream power to move large woody material. Snag, or woody, habitat is the major stable substrate in these sandy-bottomed streams and is a site of high invertebrate diversity and productivity. In-channel snag surface area per square metre of channel bottom was 0.249–0.433 m2 in the Ogeechee and 0.191–0.379 m2 in Black Creek, depending on the hydrograph stage. With invertebrate biomass of 6.6 g dry mass/m2 of snag surface, this results in an invertebrate biomass of at least 1.88 g/m2 of channel bottom. Wood is also important to fishes, providing a rich source of invertebrate food, habitat, and cover. In addition to its obvious biological role, wood enhances the ability of a stream to process and conserve nutrient and energy inputs and has a major influence on the hydrodynamic behavior of the river. The quantification of wood habitat seems mandatory to assess past or potential impacts of snag removal on ecosystem processes in low-gradient streams.