Conjunctival dermoid in two guinea pigs: a case report

Clinical and histologic findings of conjunctival dermoids in two unrelated guinea pigs are described. The dermoids were treated surgically by resection with superficial lamellar keratectomy and corneal epithelial debridement. Histologically the dermis underneath a stratified squamous keratinized and variably pigmented epithelium consisted of multiple hair follicles, with clearly visible arrectores pilorum muscles, sebaceous glands and loose vascularized fatty tissue.     

Die Anwendung von Nützlingen im biologischen Pflanzenschutz in Deutschland

Zusammenfassung Die Anwendung von Nutzarthropoden und entomopathogenen Nematoden hat in den letzten Jahren stetig zugenommen. Die Anfänge des biologischen Pflanzenschutzes mit Nützlingen in Deutschland liegen schon einige Jahrzehnte zurück. Im Freiland werden Trichogramma-Schlupfwespen seit über 25 Jahren gegen den Maiszünsler eingesetzt. Der Einsatz von Nützlingen unter Glas geht in die beginnenden 1970er zurück. Seit Anfang der 1980er werden in Deutschland Nützlinge produziert und kommerziell angeboten.Die etwa 60 eingesetzten Nützlinge sind zu mehr als 50% heimische Arten. Die von deutschen Firmen angebotenen nichtheimischen Arten sind nur an das Gewächshausklima angepasst und können dadurch nicht zur Gefahr in heimischen Ökosystemen werden. In Gewächshauskulturen, besonders in Tomaten und Gurken, ist zu fast 100% Pflanzenschutz durch Nützlinge möglich. In anderen Kulturen, wie Zierpflanzen, ist ein integrierter Schutz mit nützlingsschonenden Pflanzenschutzmitteln notwendig. Besonders Imidacloprid und verwandte, systemisch wirkende Pflanzenschutzmittel zeigen starke Nebenwirkungen auf Nützlinge.Der biologische Vorratsschutz mit Nützlingen ist seit über 6 Jahren in der Praxis erfolgreich. Biologische Bekämpfungskonzepte ermöglichen vom Getreidelager bis zum Haushalt einen verbraucherfreundlichen Schutz der Lebensmittel.In 2001 wurde der Verein der Nützlingsanbieter in Deutschland e. V. gegründet, um gemeinsame Interessen der Firmen zu vertreten. Eine Homepage soll als Informationsplattform der interessierten Öffentlichkeit die Möglichkeiten der biologischen Schädlingsbekämpfung mit Nützlingen näher bringen.     

Effects of biological,economic and management factors on tuna and billfish stock status

Commercial tunas and billfishes (swordfish, marlins and sailfish) provide considerable catches and income in both developed and developing countries. These stocks vary in status from lightly exploited to rebuilding to severely depleted. Previous studies suggested that this variability could result from differences in life‐history characteristics and economic incentives, but differences in exploitation histories and management measures also have a strong effect on current stock status. Although the status (biomass and fishing mortality rate) of major tuna and billfish stocks is well documented, the effect of these diverse factors on current stock status and the effect of management measures in rebuilding stocks have not been analysed at the global level. Here, we show that, particularly for tunas, stocks were more depleted if they had high commercial value, were long‐lived species, had small pre‐fishing biomass and were subject to intense fishing pressure for a long time. In addition, implementing and enforcing total allowable catches (TACs) had the strongest positive influence on rebuilding overfished tuna and billfish stocks. Other control rules such as minimum size regulations or seasonal closures were also important in reducing fishing pressure, but stocks under TAC implementations showed the fastest increase of biomass. Lessons learned from this study can be applied in managing large industrial fisheries around the world. In particular, tuna regional fisheries management organizations should consider the relative effectiveness of management measures observed in this study for rebuilding depleted large pelagic stocks.     

Temporal dynamics of snags and development of snag habitats in wet spruce–fir stands in east-central British Columbia

Patterns of tree mortality, rates and type of tree and snag fall, and relationships between snag characteristics and potential wildlife habitat value were estimated for hybrid spruce (Picea glauca (Moench) Voss × engelmannii Parry ex Engelm.) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) in east-central British Columbia in order to provide important parameters for deadwood modelling. We sampled 172 snags (52 spruce and 120 fir) for species, size, morphological, and habitat attributes, and used dendroecological techniques on a subsample of these (n = 158) to estimate year of death. Input of snags appeared to occur at a nearly constant rate in these stands. Estimated annual tree fall, including live trees and snags, was 5.3% for hybrid spruce and 6.1% for subalpine fir and stem breakage was more frequent than uprooting. Long-term annual snag fall rates were 4.6% for hybrid spruce and 2.9% for subalpine fir. Discriminant analysis based on time since death correctly classified snags into three decay classes for 85% and 72% of spruce and fir, respectively. Snags that potentially could provide important functions for wildlife habitat were more prevalent in fresh and intermediate classes for hybrid spruce and in intermediate and old classes for subalpine fir. The results provide valuable parameters for further development of deadwood models, which are an important tool for development of best practices for deadwood management.     

Successful mechanical eradication of spotted bass (Micropterus punctulatus (Rafinesque, 1819)) from a South African river

相似文献   

Vertebral column deformity with curved cross-stitch vertebrae in Norwegian seawater-farmed Atlantic salmon,Salmo salar L.

Pathological changes in the vertebral column of farmed Atlantic salmon in Norway have been reported since the 1990s. Based on the characteristic radiographic findings, we here present a vertebral column deformity named “curved cross-stitch vertebrae” that mainly affects the middle aspect of the vertebral column. Sixty fish, from the west/northwest coast of mid-Norway, were sampled at slaughter and examined by radiography, computed tomography (CT), necropsy, macrophotography, and histology. The vertebral deformities were radiographically graded as mild, moderate, or marked. The main differences between these grades of changes were defined by increased curving of the peripheries of endplates, reduced intervertebral spaces, and vertical displacement of the vertebrae. The curved rims of endplates were located peripheral to a continuous and approximately circular borderline. The CT studies revealed small, multifocal, hypo-attenuating, round to crescent-shaped areas in the notochord, compatible with the presence of gas. Additionally, histology revealed that the axial parts of endplates had circular zones with perforations, through which either notochordal tissue prolapsed into the vertebrae or vascularized fibrochondroid proliferations extended from the vertebrae into the notochord. Inflammation was present in many vertebral bodies. To the best of our knowledge, this is the first report of gas in the notochord of fish.     

Retention of T-bar anchor and dart tags by a wild population of African sharptooth catfish, Clarias gariepinus

A double-tagging experiment is presented that estimates tag retention by plastic dart and T-bar anchor tags in a wild population of Clarias gariepinus. It is shown that plastic dart tags are the most suitable tag as there was 100% initial retention and long-term loss of 2% per annum. T-bar anchor tags had an initial tag retention rate of 81% and no measurable long-term loss. A combination of tag design is attributed to the poor performance of T-bar anchor tags as the T-piece of the tag does not properly anchor behind the pterygiophores.     

Rapid invasion of a subtropical lake fishery in central Mozambique by Nile tilapia,Oreochromis niloticus (Pisces: Cichlidae)

• 1. Lake Chicamba, Mozambique (19°08′S; 33°08′E) is a large (116 km²) impoundment in the headwaters of the Buzi River system, which was invaded by Oreochromis niloticus in 1996 from a small (<0.3 km²) upstream reservoir.
• 2. Experimental and artisanal catch data showed no O. niloticus until January 1996; after this O. niloticus was recorded in up to 83% of experimental seine net catches, 33% of experimental gill net catches, 43% of boat angling and 23% of shore angling catches, and in 48% of artisanal gill net catches.
• 3. During the period January to March 1997, O. niloticus mean (upper, lower 95% confidence interval) yields in the artisanal fishery were 5.2 (3.6, 7.0) t month^?1.
• 4. The rapid invasion of this lake illustrates the significant invasion threat that small point‐sources of this species pose to southern African freshwater systems.
• 5. The study recommends: (1) that this species should not be used for aquaculture or fisheries enhancement in catchments that have not been invaded, and (2) that the eradication of potential point sources of O. niloticus in non‐invaded catchment systems should be considered.

Copyright © 2007 John Wiley & Sons, Ltd.     

Using occupancy models to assess the effectiveness of underwater cameras to detect rare stream fishes

1. Many conservation efforts for freshwater fishes have been undertaken; however, continuing the monitoring of both the distribution and the abundance of species to determine the effectiveness of these actions can be difficult. As species increase in rarity, they are more difficult to detect in the field, making inferences on occupancy less reliable.
2. Conventional sampling methods, such as electrofishing and seining, require the physical handling of rare fishes, which may cause stress and mortality and, consequently, compromise conservation goals and limit monitoring programmes. Non‐invasive surveillance methods, including underwater video, are playing an increasingly important role.
3. In this study, occupancy models were used to estimate the detection probability of underwater cameras as an alternative to the conventional sampling methods for rare stream fishes. Redside dace (Clinostomus elongatus), a small minnow listed as Endangered, was used as a model organism for rarity. A total of 69 historical redside dace sites were sampled using three sampling methods to determine the effect of gear type on detecting and identifying the habitat preferences of this rare minnow.
4. On average, using multiple underwater cameras is as effective at detecting a rare minnow as conventional sampling methods (backpack electrofisher and seine) and causes no harm.
5. The detection probability of both underwater cameras and backpack electrofishing were adversely affected by turbidity, whereas seining was positively affected by stream velocity. The probability of occupancy of redside dace is driven by open channels and sediment size, and this provides a strong basis for informing stream restoration projects.
6. The use of multiple underwater cameras over conventional sampling methods is recommended when sampling for rare and endangered minnows in systems with low turbidity.