Seasonal abundance and movement of the invasive round goby (Neogobius melanostomus) on rocky substrate in the Duluth–Superior Harbor of Lake Superior

Abstract – Despite its small size [adult: 60–130 mm, total length (TL)] and limited home range, the round goby (Neogobius melanostomus) has quickly become established throughout the Laurentian Great Lakes. Little information is available, however, on the natural dispersal pattern of this species. This capture–mark–recapture study utilised alphanumeric tags subcutaneously inserted into round gobies (n = 1228) along a 550‐m stretch of the Duluth–Superior Harbor shoreline to observe their movement over a 13‐month period. Recaptured round gobies (n = 415) exhibited highly leptokurtic movement distributions, and movement events were not correlated with fish size, gender or month. Our work indicates that round gobies >50 mm (TL) generally occupy an area less than the minimum sampling interval (25 m); however, occasional movement up to 50 m per day could facilitate range expansion in the Laurentian Great Lakes.     

Implications of recreational fishing for elasmobranch conservation in the Great Barrier Reef Marine Park

• 1. 309 Great Barrier Reef Marine Park recreational fishers were surveyed to examine recreational catch and harvest of elasmobranchs and to explore recreational fishers' handling behaviour and attitudes.
• 2. Elasmobranchs represented 6% of fishers' total catch of all fish (including released individuals), and 0.8% of fishers' total harvest (i.e. retained individuals) across all survey days. The majority of elasmobranchs caught by fishers were released, primarily because they were perceived as being inedible.
• 3. Recreational fishers' self‐reported handling and release behaviour for elasmobranchs is largely consistent with ‘best practice’ guidelines except that fishers had low use of circle hooks and barbless hooks, and a significant proportion (33%) reported using stainless steel hooks.
• 4. Most fishers had positive attitudes towards elasmobranchs, placing high importance on releasing sharks and rays in good condition (86%), high value on their existence (84%), and low value on catching them (63%).
• 5. Results indicate that post‐release mortality is probably the largest source of recreational fishing mortality of elasmobranchs in the Great Barrier Reef. Future research should be targeted at obtaining better estimates of species‐specific post‐release mortality levels, understanding how post‐release survival can be increased by changing fishing techniques or fisher behaviour, and developing more effective methods of engaging fishers in elasmobranch conservation. Copyright © 2009 John Wiley & Sons, Ltd.

     

Soil enzyme activities in the rhizosphere of field-grown sugar beet inoculated with the biocontrol agent Pseudomonas fluorescens F113

Pseudomonas fluorescens F113, which produces the antimicrobial compound 2,4-diacetylphloroglucinol, is a prospective biocontrol agent. Soil enzyme activities were used to investigate the ecological impact of strain F113 in the rhizosphere of field-grown sugar beet. There were distinct trends in rhizosphere enzyme activities in relation to soil chemistry [determined by electro-ultrafiltration (EUF)]. The activities of enzymes from the P cycle (acid phosphatase, alkaline phosphatase and phosphodiesterase) and of arylsulphatase were negatively correlated with the amount of readily available P, whereas urease activity was positively correlated with the latter. Significant correlations between nutrient levels determined by EUF and enzyme activities in the rhizosphere were obtained, highlighting the usefulness of enzyme assays to document variations in soil nutrient cycling. Contrary to previous microcosm studies, which did not investigate plants grown to maturity, the biocontrol inoculant had no effect on enzyme activities or on soil chemistry in the rhizosphere. The results showed the importance of using homogenous soil microcosm systems, also employed in previous work, for risk assessment studies, whereby the effects of inherent soil variability were minimised, and effects of the pseudomonad on soil enzymology could be detected. Received: 3 February 1997     

Multi-year evaluation ofClavibacter michiganensis subsp.sepedonicus disease symptoms in cultivated potato genotypes

The expression of foliar and tuber bacterial ring rot (BRR) symptoms in 108 cultivated potato genotypes inoculated withClavibacter michiganensis subsp.sepedonicum was examined in field experiments during 1986 to 1996. Considerable variation in the incidence of foliar BRR symptoms was observed in all plant cultivars, ranging from no detectable symptoms to complete necrosis of the leaves. Similar variability was observed in the incidence of tuber BRR symptoms, and severity of tuber symptoms ranged from no detected symptoms to complete breakdown of the vascular ring that extended throughout the tuber. A decline in the incidence and severity of tuber, but not foliar symptoms, was observed in the later years of the study (P<0.05). Foliar and tuber BRR symptoms generally were positively correlated (P<0.01) prior to 1993 but not in subsequent years (P>0.05) when tuber symptoms declined. Strong correlations were observed between the incidence and severity of foliar BRR symptoms (r=0.41, P<0.01) and between the incidence and severity of tuber BRR symptoms (r=0.96, P<0.001). During the 11 year period, no BRR symptoms were observed in 2,620 uninoculated control plants.     

DOHUBLE-PHASE PARATHYROID SCINTIGRAPHY IN DOGS USING TECHNETIUM-99M-SESTAMIBI

The purpose of this study was to evaluate the utility of double-phase parathyroid scintigraphy using 99mTc-sestamibi for detecting and localizing hyperfunctioning parathyroid glands in hypercalcemic dogs. Fifteen hypercalcemic dogs that underwent parathyroid scintigraphy were included in this study: 3 dogs with hypercalcemia of malignancy, and 12 dogs with hyperfunctioning parathyroid tissue (parathyroid adenoma or parathyroid hyperplasia). The presence of parathyroid adenoma or parathyroid hyperplasia was documented by histopathologic examination. In 3 dogs with hypercalcemia of malignancy, parathyroid scintigraphy was negative for hyperfunctioning parathyroid tissue and the scans were classified as true negative. Parathyroid scintigraphy correctly identified the presence and location of hyperfunctioning parathyroid tissue in only 1 of 6 dogs with a parathyroid adenoma. False positive and false negative results occurred in dogs with parathyroid adenomas. Parathyroid scintigraphy failed to detect hyperfunctioning parathyroid tissue in 5 of 6 dogs with parathyroid hyperplasia and were classified as false negative. False positive results were obtained in the remaining dog with parathyroid hyperplasia. Sensitivity of parathyroid scintigraphy for detecting and localizing hyperfunctioning parathyroid tissue was 11%, specificity was 50%, and overall accuracy was 27%. Positive and negative predictive value were 25% and 27%, respectively. Sensitivity for detection of parathyroid adenomas was 25%, and sensitivity for detection of hyperplastic glands was 0 %. Results of this study indicate that double-phase parathyroid scintigraphy does not appear to have acceptable accuracy in detecting hyperfunctioning parathyroid glands in dogs. Due to the poor sensitivity and specificity of the technique in dogs, parathyroid scintigraphy is not recommended for definitive identification of abnormal parathyroid glands as the cause of hypercalcemia in dogs.     

THE COMPUTED TOMOGRAPHIC APPEARANCE OF ACUTE THORACOLUMBAR INTERVERTEBRAL DISC HERNIATIONS IN DOGS

The appearance of herniated intervertebral disc material in the thoracolumbar vertebral canal was evaluated in 23 dogs using computed tomography (CT). The images were then compared with the myelographic and surgical findings. The normal spinal cord, outlined by epidural fat over intervertebral disc spaces, was of intermediate attenuation on transverse CT images. Herniated disc material was identified in all animals as a heterogeneous hyperattenuating extradural mass. The attenuation of the disc material increased with the degree of mineralization. In seven dogs, the herniated material was only slightly more attenuating than the spinal cord. In these dogs, small fragments of mineralized disc material and significant hemorrhage were found in the epidural space at surgery. In dogs with a long standing history of disc herniations, disc material identified in the vertebral canal had a more hyperattenuating and homogeneous appearance than recently herniated disc material. We conclude that mineralized, herniated disc material and hemorrhage can be identified quickly and safely in dogs using CT.     

Long-term suppression of Pythium ultimum in arid soil using fresh and composted municipal wastes

 The effect of addition of municipal solid waste (MSW) at different degrees of stabilisation on the biological properties of an arid soil was studied 24 months after application. This included effects on the indigenous soil microflora and soil enzyme activities in the presence and absence of Pythium ultimum. The addition of organic waste (fresh or composted) reduced populations of culturable bacteria and fungi and disease symptoms caused by P. ultimum, and resulted in heavier plants with longer and more extensively branched roots. Addition of organic waste increased the population size of culturable bacteria and fungi, while enzymatic activity of the soil was higher in soil amended with organic matter than in non-amended soil. Populations of biological control agents, such as Trichoderma and fluorescent pseudomonads, were larger in soil amended with organic matter. The addition of urban waste could therefore be a suitable technique with which to restore soil quality by stimulating biological control against plant pathogens such as P. ultimum. Received: 3 May 1999     

EVALUATION OF ORAL IRON GALACTAN AS A METHOD OF IRON SUPPLEMENTATION FOR INTENSIVELY HOUSED SUCKING PIGLETS

SUMMARY Iron supplementation of piglets with oral galactan given as a single dose within 24 hours of birth was evaluated in a series of on farm trials. The growth rate of piglets receiving this treatment was faster than that of piglets receiving single injections of iron dextran or iron galactan at 3 days of age, or ferrous sulphate crystals orally at weekly intervals. Mean values for red cell parameters of oral iron galactan supplemented piglets at 2 to 4 weeks of age were lower than those of injected piglets but there was no clinical evidence of anaemia in any of the piglets.