Linkages between seagrass,mangrove and saltmarsh as fish habitat in the Botany Bay estuary,New South Wales

Shallow-water vegetated estuarine habitats, notably seagrass, mangrove and saltmarsh, are known to be important habitats for many species of small or juvenile fish in temperate Australia. However, the movement of fish between these habitats is poorly understood, and yet critical to the management of the estuarine fisheries resource. We installed a series of buoyant pop nets in adjacent stands of seagrass, mangrove and saltmarsh in order to determine how relative abundance of fishes varied through lunar cycles. Nets were released in all habitats at the peak of the monthly spring tide for 12 months, and in the seagrass habitat at the peak of the neap tide also. The assemblage of fish in each habitat differed during the spring tides. The seagrass assemblage differed between spring and neap tide, with the neap tide assemblage showing greater abundances of fish, particularly those species which visited the adjacent habitats when inundated during spring tides. The result supports the hypothesis that fish move from the seagrass to the adjacent mangrove and saltmarsh during spring tides, taking advantage of high abundances of zooplankton, and use seagrass as a refuge during lower tides. The restoration and preservation of mangrove and saltmarsh utility as fish habitat may in some situations be linked to the proximity of available seagrass.     

Biodegradation of 2,4,6-trinitrotoluene byPhanerochaete chrysosporium: Identification of initial degradation products and the discovery of a TNT metabolite that inhibits lignin peroxidases

Biodegradation of 2,4,6-trinitrotoluene (TNT) by the wood-rotting BasidiomycetePhanerochaete chrysosporium was studied in a fixed-film silicone membrane bioreactor and in agitated pellected cultures. The initial intermediate products of TNT biodegradation were shown to be 2-amino-4,6-dinitrotoluene (2amDNT) and 4-amino-2,6-dinitrotoluene (4amDNT). These intermediates were also degraded byP. chrysosporium. However, their rates of degradation were slow and appeared to represent rate-limiting steps in TNT degradation. The fact that 2amDNT and 4amDNT were further degraded is of importance. In most other microbial systems these compounds are typically not further degraded or are dimerized to even more persistent azo and azoxydimers. Similar to previous studies performed in stationary cultures, it was shown that substantial amounts of [¹⁴C]-TNT were degrade to [¹⁴C]-carbon dioxide in agitated pelleted cultures. Lignin peroxidase activity (assayed by veratryl alcohol oxidation) virtually disappeared upon addition of TNT to ligninolytic cultures ofP. chrysosporium. However, TNT, 2amDNT, and 4amDNT did not inhibit lignin peroxidase activity, nor were they substrates for this enzyme. Subsequent studies revealed that 4-hydroxylamino-2,6-dinitrotoluene, an intermediate in TNT reduction, was a potent lignin peroxidase inhibitor. Further studies revealed that this compound was also a substrate for lignin peroxidase H8.     

Viral and Bacterial Pathogens in Bovine Respiratory Disease in Finland

Pathogens causing bovine respiratory tract disease in Finland were investigated. Eighteen cattle herds with bovine respiratory disease were included. Five diseased calves from each farm were chosen for closer examination and tracheobronchial lavage. Blood samples were taken from the calves at the time of the investigation and from 86 calves 3–4 weeks later. In addition, 6–10 blood samples from animals of different ages were collected from each herd, resulting in 169 samples. Serum samples were tested for antibodies to bovine parainfluenza virus-3 (PIV-3), bovine respiratory syncytial virus (BRSV), bovine coronavirus (BCV), bovine adenovirus-3 (BAV-3) and bovine adenovirus-7 (BAV-7). About one third of the samples were also tested for antibodies to bovine virus diarrhoea virus (BVDV) with negative results. Bacteria were cultured from lavage fluid and in vitro susceptibility to selected antimicrobials was tested. According to serological findings, PIV-3, BAV-7, BAV-3, BCV and BRSV are common pathogens in Finnish cattle with respiratory problems. A titre rise especially for BAV-7 and BAV-3, the dual growth of Mycoplasma dispar and Pasteurella multocida, were typical findings in diseased calves. Pasteurella sp. strains showed no resistance to tested antimicrobials. Mycoplasma bovis and Mannheimia haemolytica were not found.     

Substrate-dependent inhibition of yeast enolase by fluoride

A possibly physiologically significant inhibition of yeast enolase by fluoride occurs in the absence of inorganic phosphate. The inhibition increases with time, is strongly dependent on fluoride concentration and requires substrate and “catalytic” Mg²⁺. The inhibition increases more slowly in the presence of product (phosphoenolpyruvate) than substrate (2-phosphoglycerate). The dependence on fluoride concentration and the spans of substrate analogue displacement titrations suggest the inhibition is produced by two moles of fluoride per active site.     

Habitat characteristics contributing to local occupancy and habitat use in rock pool <Emphasis Type="Italic">Daphnia</Emphasis> metapopulations

The effects of invasive macrophytes, water level fluctuations and predation on freshwater unionids Pyganodon grandis and Utterbackia imbecillis were studied in three small impoundments in Northeastern Texas in 2003–2005. Mussel density was sampled with quadrats. Mortality, associated with the water level fluctuations and predation, was estimated by collecting dead shells on the shore at about two month intervals. In two ponds, horizontal distribution of unionids was limited by dense beds of invasive and noxious macrophytes (mainly Eurasian watermilfoil Myriophyllum spicatum and American lotus Nelumbo lutea): mussel densities were significantly lower in these macrophyte beds (P < 0.001). In the third pond with the lowest density of macrophytes (stonewort Chara sp.), unionids were distributed more evenly, and the average unionid biomass was the highest among all ponds studied. Vertical distribution of unionids in all ponds was likely limited by low oxygen at depth >2 m. The total amount of shells found on the shore per year varied from 0.1% to 28% of the total population in the pond and was negatively correlated with water level (r = −0.72 to −0.81, P < 0.005). Mammalian predators consumed up to 19% of the total unionid population and predation was facilitated by water level fluctuations. Handling editor: K. Martens     

Huxley: From Devil's Disciple to Evolution's High Priest

Huxley: From Devil's Disciple to Evolution's High Priest. Adrian Desmond. Reading. MA: Addison-Wesley. 1997.820 pp.