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Artificial Habitats (artificial + habitat)
Selected AbstractsMitochondrial and microsatellite DNA markers reveal a Balkan origin for the highly invasive horse-chestnut leaf miner Cameraria ohridella (Lepidoptera, Gracillariidae)MOLECULAR ECOLOGY, Issue 16 2009R. VALADE Abstract Biological invasions usually start with a small number of founder individuals. These founders are likely to represent a small fraction of the total genetic diversity found in the source population. Our study set out to trace genetically the geographical origin of the horse-chestnut leafminer, Cameraria ohridella, an invasive microlepidopteran whose area of origin is still unkown. Since its discovery in Macedonia 25 years ago, this insect has experienced an explosive westward range expansion, progressively colonizing all of Central and Western Europe. We used cytochrome oxidase I sequences (DNA barcode fragment) and a set of six polymorphic microsatellites to assess the genetic variability of C. ohridella populations, and to test the hypothesis that C. ohridella derives from the southern Balkans (Albania, Macedonia and Greece). Analysis of mtDNA of 486 individuals from 88 localities allowed us to identify 25 geographically structured haplotypes. In addition, 480 individuals from 16 populations from Europe and the southern Balkans were genotyped for 6 polymorphic microsatellite loci. High haplotype diversity and low measures of nucleotide diversities including a significantly negative Tajima's D indicate that C. ohridella has experienced rapid population expansion during its dispersal across Europe. Both mtDNA and microsatellites show a reduction in genetic diversity of C. ohridella populations sampled from artificial habitats (e.g. planted trees in public parks, gardens, along roads in urban or sub-urban areas) across Europe compared with C. ohridella sampled in natural stands of horse-chestnuts in the southern Balkans. These findings suggest that European populations of C. ohridella may indeed derive from the southern Balkans. [source] Harbour swimming nets: a novel habitat for seahorsesAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 5 2008B. G. Clynick Abstract 1.Artificial structures are becoming increasingly important in conserving biodiversity in urban ecosystems, by providing habitat for endangered or rare species. Their role in providing habitat for such species has, however, been largely unexplored. 2.In Sydney Harbour, Australia, seahorses were observed among the netting used to keep sharks out of swimming enclosures. Over a 2-year period, the relative densities of two species of seahorses observed on netting was measured at swimming enclosures with permanent netting and at swimming areas that were only enclosed with netting during the summer months. 3.The rate of colonization by seahorses to new netting was also examined over a period of 10 months. 4.Numbers of seahorses on permanent swimming enclosures were 10 to 100 times greater than numbers present on swimming enclosures that were only set up during the summer months. 5.This large difference may have been attributed to the slow rate of colonization of seahorses to new habitat. Seahorses were not observed at experimental nets that were deployed in two areas in the harbour until at least 4 months after the netting was deployed. 6.Swimming pool nets are a habitat for species of seahorses in Sydney Harbour and, consequently, the removal or disturbance of swimming nets may impact the survival of these fish. Management of these artificial habitats may therefore best be focused on providing a permanent habitat that may help to compensate for the loss of netting during winter months. Copyright © 2007 John Wiley & Sons, Ltd. [source] Assessing adult Trichoptera communities of small streams: a case study from Charnwood Forest, Leicestershire, UKAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 2 2001M.T. Greenwood Abstract 1.,Adult caddisflies were collected using non-attracting Malaise traps at four sites on a small headwater stream from May to November 1990. Sites S1 and S2 were most natural and upstream of a reservoir; where S3 was located in the bypass channel, and S4, downstream. 2.,The flight period for each species is recorded to provide baseline data. Flight activity patterns fall into two groupings: (a) species with a flight activity of 3,4 months, and (b) those species with a short flight period of up to 6 weeks. 3.,Sixty-one species from 15 families were collected, including the endangered Red Data Book species Tinodes pallidulus McLachlan. 4.,Significant differences in community parameters are shown among all sites, many species apparently having local catchment areas. The influence of artificial habitats, the open bypass channel and adjacent reservoir, is clearly demonstrated. 5.,The data illustrate the potential of using adult caddisflies in conservation assessment of small streams. Working with adults is taxonomically rigorous and they are useful bioindicators of the environmental quality of the valley floor corridor. Copyright © 2001 John Wiley & Sons, Ltd. [source] Densities of polychaetes in habitat fragments depend on the surrounding matrix but not the complexity of the remaining fragmentAUSTRAL ECOLOGY, Issue 4 2009VICTORIA J. COLE Abstract Biogenically engineered habitats are constantly changing in space and time, resulting in changes to the landscape and the ecology of associated taxa. Using patchily distributed biogenic habitats on intertidal rocky shores the influences of different aspects of the landscape were investigated, that is, the surrounding matrix and the habitat itself. Experiments to test the effect of the matrix were carried out by transplanting assemblages in artificial habitats from one type of biogenically engineered matrix (created by the tubeworm Galeolaria caespitosa) to another (created by the oyster Saccostrea glomerata). Change to the surrounding matrix resulted in the densities of polychaete worms in central fragments of habitat changing to become more similar to their new surroundings. To test how the habitat influenced predator,prey interactions, polychaetes were transplanted from a complex habitat (created by the turfing alga Corallina officinalis) to less complex habitat (created by the tubeworm G. caespitosa), with or without the presence of the predatory polychaete, Perinereis amblyodonta. This experiment also tested the influence of habitat replacement on densities of polychaetes, regardless of any new interactions between species. Despite coralline turf being a much more complex habitat than Galeolaria, P. amblyodonta successfully preyed on other species of polychaetes in both habitats. Furthermore, in the absence of P. amblyodonta, survival of polychaetes did not differ between the habitats. These types of experiments will be useful for testing similar hypotheses in different landscapes and will assist in gaining a more general understanding of habitat modification. [source] Fish assemblages associated with urban structures and natural reefs in Sydney, AustraliaAUSTRAL ECOLOGY, Issue 2 2008B. G. CLYNICK Abstract Fish ecology in urban estuaries is poorly understood. As coastal landscapes are transformed, recognizing the impact that urban structures, such as marinas, seawalls and wharfs, have on local fish populations is becoming increasingly important. The extent to which fish are able to maintain natural ecological assemblages can be measured, to a certain extent, by how closely they mimic natural habitats. In Sydney Harbour, assemblages of fish associated with artificial structures were compared with those associated with natural rocky reefs. Sampling was carried out in five locations, each with a marina, swimming enclosure and natural reef. In each location, different habitats supported different assemblages, but differences between habitats were not consistent among locations. Subsequent sampling compared artificial and natural sites in three different areas in each of three different estuaries. Results indicated that differences in fish assemblages between artificial and natural sites were greater than differences between sites within each habitat, but there were no patterns among different positions in an estuary or from estuary to estuary. This study provides initial evidence that, although artificial habitats generally support the same species as found on natural reefs, assemblages usually differed between natural and artificial habitats. In addition, without knowing if these habitats do, in fact, sustain viable populations of fish, it would be premature to label artificial structures as effective habitat for fish. [source] | ||||||||||