Nitrogen acquisition and resource allocation strategies in temperate seagrass Zostera nigricaulis: Uptake, assimilation and translocation processes.

The dominant seagrass in Port Phillip Bay (PPB), Australia, Zostera nigricaulis, declined between 2000 and 2011, coinciding with the 'Millennium drought' that ended in 2009. These seagrasses are nitrogen-limited, underpinning the need to develop nitrogen budgets for better ecosystem management. Environmentally realistic measurements of specific uptake rates and resource allocation were undertaken to develop nitrogen budgets and test the hypothesis that the above-ground and below-ground compartments are able to re-mobilise ammonium and nitrate through uptake, translocation and assimilation to adapt to varying levels of nitrogen in the ecosystem. Uptake of 15N labelled ammonium and nitrate by above- and below-ground seagrass biomass, epiphytes and phytoplankton was quantified in chambers in situ. Preferential uptake of ammonium over nitrate was observed, where the uptake rate for nitrate was about one sixth of that for ammonium. Epiphytes and phytoplankton also registered an increased affinity for ammonium over nitrate. Translocation experiments demonstrated the uptake by both the above-ground and below-ground biomass, respectively from the water column and pore water, and subsequent translocation to the opposite compartment. Acropetal translocation (below- to above-ground biomass) was more prevalent than basipetal translocation. This is a unique outcome given basipetal translocation has been widely reported for Zostera by other researchers.

Influence of freshwater flows on the distribution of eggs and larvae of black bream Acanthopagrus butcheri within a drought-affected estuary.

This study tested the hypothesis that variable freshwater flow in the Gippsland Lakes, Australia, influences the location and extent of environmental conditions suitable for spawning and larval development of black bream, Acanthopagrus butcheri. Freshwater flow had a large influence on the salinity and level of stratification (difference between bottom and surface salinity) in the Gippsland Lakes. Freshwater flows throughout this study varied from no or low flows through to major flooding in 2007. Eggs of A. butcheri were found in similar concentrations throughout the lakes and rivers. More than 99% of larvae, however, were collected from within rivers, with very few larvae being collected from the lakes. A comparison of two spawning seasons revealed that the year with higher freshwater flows also had greater spawning activity and higher concentrations of larvae. Interestingly, there was a significant relationship between the distribution of eggs and larvae with the level of stratification. The highest concentrations of larvae occurred at sites with a difference in bottom and surface salinities of 15-20. This study demonstrates that despite A. butcheri spawning in the lakes and rivers, it is only locations with a halocline that function as larval nursery habitat.

Fine-scale spatial and temporal variations in diets of the pipefish Stigmatopora nigra within seagrass patches.

Diets of the pipefish Stigmatopora nigra were analysed to determine if food availability was causing S. nigra to distribute according to habitat edge effects. Gut analysis found little difference in the diets of S. nigra at the edge and interior of seagrass patches, regardless of time of day or season. Fish diets did, however, vary with seagrass density: S. nigra in denser seagrass consumed more harpacticoid copepods and fewer planktonic copepods. The lack of difference in prey eaten by S. nigra at the edge and interior of patches suggests either that food was not determining S. nigra distribution patterns within patches or that differences in fish densities across patches meant that relative fish-prey densities were similar at edge and interior positions. Alternatively, any edge effects in diet might be masked by gradients in seagrass structure.

Feeding ecology of King George whiting Sillaginodes punctatus (Perciformes) recruits in seagrass and unvegetated habitats. Does diet reflect habitat utilization?

This study investigated the feeding ecology of King George whiting Sillaginodes punctatus recruits to determine how diet composition varies between habitat types (seagrass and unvegetated habitats), and between sites separated by distance. Broad-scale sampling of seagrass and unvegetated habitats at nine sites in Port Phillip Bay (Australia) indicated the diet composition varied more by distance into the bay than by habitat. Near the entrance to the bay the diet was dominated by harpacticoids and gammarid amphipods, in the middle reaches of the bay the diet was completely dominated by harpacticoids, while at sites furthest into the bay, mysids and crab zoea were also important. Abundances of prey in guts was significantly higher between 1000 and 2200 hours compared with other times, indicating diurnal feeding. Laboratory determined gut evacuation rate (based on an exponential model) was estimated to be -0·54. Daily rations were highly variable among sites and habitat types. Sillaginodes punctatus recruits consumed much higher quantities of prey on unvegetated habitat than seagrass habitat at some middle reach sites; with prey consumption of harpacticoid copepods on unvegetated habitat approaching 3000 individuals per day at one site. The results of this study provide insight into why habitat associations of S. punctatus recruits within mosaics of seagrass and unvegetated habitat show high spatial variation.

Connectivity of a large embayment and coastal fishery: spawning aggregations in one bay source local and broad-scale fishery replenishment.

Ichthyoplankton sampling and otolith chemistry were used to determine the importance of transient spawning aggregations of snapper Chrysophrys auratus (Sparidae) in a large embayment, Port Phillip Bay (PPB), Australia, as a source of local and broad-scale fishery replenishment. Ichthyoplankton sampling across five spawning seasons within PPB, across the narrow entrance to the bay and in adjacent coastal waters, indicated that although spawning may occur in coastal waters, the spawning aggregations within the bay were the primary source of larval recruitment to the bay. Otolith chemical signatures previously characterized for 0+ year C. auratus of two cohorts (2000 and 2001) were used as the baseline signatures to quantify the contribution that fish derived from reproduction in PPB make to fishery replenishment. Sampling of these cohorts over a 5 year period at various widely dispersed fishery regions, combined with maximum likelihood analyses of the chemistry of the 0+ year otolith portions of these older fish, indicated that C. auratus of 1 to 3+ years of age displayed both local residency and broad-scale emigration from PPB to populate coastal waters and an adjacent bay (Western Port). While the PPB fishery was consistently dominated (>70%) by locally derived fish irrespective of cohort or age, the contribution of fish that had originated from PPB to distant populations increased with age. At 4 to 5+ years of age, when C. auratus mature and fully recruit to the fishery, populations of both cohorts across the entire central and western Victorian fishery, including two major embayments and c. 800 km of coastal waters, were dominated (>70%) by fish that had originated from the spawning aggregations and nursery habitat within PPB. Dependence of this broadly dispersed fishery on replenishment from heavily targeted spawning aggregations within one embayment has significant implications for management and monitoring programmes.

Integrating edge effects into studies of habitat fragmentation: a test using meiofauna in seagrass.

Habitat fragmentation is thought to be an important process structuring landscapes in marine and estuarine environments, but effects on fauna are poorly understood, in part because of a focus on patchiness rather than fragmentation. Furthermore, despite concomitant increases in perimeter:area ratios with fragmentation, we have little understanding of how fauna change from patch edges to interiors during fragmentation. Densities of meiofauna were measured at different distances across the edges of four artificial seagrass treatments [continuous, fragmented, procedural control (to control for disturbance by fragmenting then restoring experimental plots), and patchy] 1 day, 1 week and 1 month after fragmentation. Experimental plots were established 1 week prior to fragmentation/disturbance. Samples were numerically dominated by harpacticoid copepods, densities of which were greater at the edge than 0.5 m into patches for continuous, procedural control and patchy treatments; densities were similar between the edge and 0.5 m in fragmented patches. For taxa that demonstrated edge effects, densities exhibited log-linear declines to 0.5 m into a patch with no differences observed between 0.5 m and 1 m into continuous treatments. In patchy treatments densities were similar at the internal and external edges for many taxa. The strong positive edge effect (higher densities at edge than interior) for taxa such as harpacticoid copepods implies some benefit of patchy landscapes. But the lack of edge effects during patch fragmentation itself demonstrates the importance of the mechanisms by which habitats become patchy.

A randomized controlled trial of the effects of group psychological therapy on survival in women with metastatic breast cancer.

In order to test the effect of a psychological intervention on survival from cancer, 66 women with metastatic breast cancer, all receiving standard medical care, were randomly assigned into two groups; one group (n = 30) attended the psychological intervention, consisting of 35 weekly, 2 h sessions of supportive plus cognitive behavioral therapy; the control group (n = 36) received only a home study cognitive behavioral package. No significant difference was found in survival post-randomization between the groups as assessed by a log rank test 5 years after the commencement of the study. As expected, several prognostic factors were significant predictors of survival: metastatic site, hormonal receptor status, and chemotherapy prior to randomization. While many personal and demographic variables did not influence survival, there was a significant effect of self-reported exercise (possibly due to better health). A small subgroup of intervention subjects who attended outside support groups also survived significantly longer than those who did not. The strengths and limitations of the present study are discussed, and the results contrasted with those of a well known study by Spiegel et al. (Spiegel, D., Bloom, J.R., Kraemer, H.C. and Gottheil, E. (1989) Lancet ii, 888-891). We propose that a different experimental design (correlative) may be needed to show any effect of self-help behaviors and psychological attributes in a small minority of patients.

Implications of economic transition and demographics for financing pensions in the former socialist economies.

"This paper is concerned primarily with the financing of pensions, or the old-age income maintenance portion of the social security system. While the discussion here will be limited to Hungary and Poland, most of the post-socialist countries of East and Central Europe and of the former Soviet Union face similar problems." The author suggests "a set of alternative pension financing strategies....A novel approach is to replace the payroll tax with part of a value-added tax, which may be a good short run solution to current financial crises of the pension systems in these countries."