The fallacy of the missing middle: physics →…→ fisheries

In this paper I discuss some of the shortcomings of today's marine science in response to a recently published paper by Ann Gargett (1997). Three problem areas have been identified in the field linking climate forcing and fish production: First, the yet-to-be established observational proof for a relationship between the two; Second, the strongly neglected biology of organisms at evolutionary and ecological time scales; and thrird, the disregard for spatial and temporal scales in the discussion of mechanisms and supporting data.     

Use of low dose prostaglandin for the treatment of canine pyometra

Ten bitches with pyometra were treated with prostaglandin F_2α at a dose of 20 μg/kg bodyweight three times daily on consecutive days. Diagnosis was based on clinical signs and radiographic findings. Venous blood samples were collected for haematology and measurement of plasma progesterone levels. The response to treatment was monitored by repeated ultrasonic examinations. The treatment was continued for up to eight days. Seven out of 10 bitches responded well to treatment. The remaining three bitches underwent ovariohysterectomy and a cystic hyperplasia of the endometrium was diagnosed histologically. The results indicated that prostaglandin F_2α used at the low dose is sufficient for medical treatment of certain cases of pyometra. The treatment seems to be most effective in bitches without obvious hormonal imbalance. The aetiology of pyometra is discussed.     

Linking growth to environmental histories in central Baltic young-of-the-year sprat, Sprattus sprattus: an approach based on otolith microstructure analysis and hydrodynamic modelling

Otolith microstructure analysis and hydrodynamic modelling were combined to study growth patterns in young‐of‐the‐year (YoY) sprat, Sprattus sprattus, which were sampled in October 2002 in the central Baltic Sea. The observed ‘window of survival’, approximated by the distribution of back‐calculated days of first feeding (DFF), was narrow compared to the extended spawning season of sprat in the Baltic Sea (mean± SD = 22 June ± 14.1 days) and indicated that only individuals born in summer survived until October 2002. Within the group of survivors, individuals born later in the season exhibited faster larval, but more rapidly decreasing juvenile growth rates than earlier born conspecifics. Back‐calculated larval growth rates of survivors (0.48–0.69 mm day^?1) were notably higher than those previously reported for average larval sprat populations, suggesting that the YoY population was predominantly comprised of individuals which grew faster during the larval stage. Daily mean temperatures, experienced across the entire YoY population, were derived from Lagrangian particle simulations and correlated with (1) detrended otolith growth and (2) back‐calculated, daily somatic growth rates of survivors. The results showed that abrupt changes in ambient temperature can be detected in the seasonal pattern of otolith growth, and that higher temperatures led to significantly faster growth throughout the entire age range of YoY sprat.     

Changes in the Appalachian Wage Gap, 1970 to 2000

ABSTRACT Since at least 1960, Appalachia has had lower wages, employment rates, and educational attainment than the rest of the country. Using a sample from the Integrated Public Use Microdata Series Census project, the author identifies factors affecting the wage gap between 1970 and 2000. The author finds that increases in educational attainment in Appalachia are counterbalanced by increasing returns to observable and unobservable skill, the decline of the manufacturing industry, and rising wage dispersion, leaving the wage gap for full‐time workers in 2000 at essentially the same levels as 1970.     

Focus on ecological weed management: what is hindering adoption?

Despite increased concerns regarding the heavy reliance of many cropping systems on chemical weed control, adoption of ecological weed management practices is only steadily progressing. For this reason, this paper reflects on both the possibilities and limitations of cultural weed control practices. Cultural weed control utilises a number of principles, predominantly: (i) a reduced recruitment of weed seedlings from the soil seedbank, (ii) an alteration of crop–weed competitive relations to the benefit of the crop and (iii) a gradual reduction of the size of the weed seedbank. Compared with chemical control, the general applicability, reliability and efficacy of most measures is only moderate, and consequently, cultural control strategies need to consist of a combination of measures, resulting in increased systems complexity. Combined with the trade‐offs connected to some of the measures, this hampers large‐scale implementation. It is argued that tailoring cultural weed management strategies to the needs and skills of individual farmers would be an important step forward. Research can aid in improving the utilisation of cultural weed control strategies by focussing on a broadening of the range of available measures and by providing clear quantitative insight in efficacy, variability in outcome and trade‐offs of these measures.     

A comment on transfer efficiencies

This paper discusses the validity of several assumptions in a recent publication on the primary production required to sustain the annual world fish catch of £120 million t. A transfer efficiency between trophic levels in aquatic ecosymms of 15% results in the primary production requirement of 2.6% of the total primary production to sustain the world fish catch, not 8% as reported from calculations with a transfer efficiency of 10%. The importance of accurate estimates of predation efficiency and trophic level is shown.