Photo-identification, site fidelity, and movement of female gray seals (Halichoerus grypus) between haul-outs in the Baltic Sea

The growing gray seal population in the Baltic Sea has led to increased conflicts with fisheries. Despite limited data on gray seal ecology, management measures, such as culling, have been implemented recently. We studied movements and site fidelity of Baltic gray seals using mark-recapture analysis based on photographic identification of individuals (photo-id). Seals were photographed at the major summer haul-out sites. Profile photographs of the head and neck were matched using purpose-written software to generate a database of capture histories from 1995-2000. The haul-outs were grouped into seven areas. Darroch's method (20) for a two-sample capture-recapture census was adapted to estimate rates of movement between the areas. The majority of seals were estimated to remain within the same area, suggesting that Baltic gray seals exhibit a high degree of site fidelity during the summer, and that fidelity to a site lasts for more than one season.     

Simulations of stomatal conductance and ozone uptake to Norway spruce saplings in open-top chambers

A simulation model was developed to estimate the stomatal conductance and ozone flux to Norway spruce saplings in open-top chambers. The model was parameterized against needle conductance measurements that were made on 4-6-year-old spruce saplings, grown in open-top chambers, in July-September during three different seasons. The spruce saplings were either maintained well watered or subject to a 7-8 week drought period in July-September each year. The simulated conductance showed a good agreement with the measured conductance for the well-watered as well as the drought stress-treated saplings. The simulations were significantly improved when different vapour pressure deficit (VPD) functions were applied for well-watered and drought-stressed spruce saplings. The cumulated ozone uptake which was calculated from the conductance simulations showed less variation between years, compared to the cumulative ozone exposure index AOT40 (accumulated exposure over a threshold of 40 ppb or nl l(-1)) for the corresponding time periods. Measurements in May 1995 demonstrated the occurrence of long-term 'memory-effects' from the drought stress treatments on the conductance. Memory-effects need to be considered when simulation models for stomatal conductance are to be applied to long-lived forest trees under a multiple stress situation.     

PREDICTING THE SUMMER PEAK BIOMASS OF FOUR SPECIES OF BLUE-GREEN ALGAE (CYANOPHYTA/CYANOBACTERIA) IN SWEDISH LAKES1

ABSTRACT: Stepwise multiple regression analysis was used to develop models predicting the summer peak biomass of Aphanizomenon flos-aquae, Anabaena flos-aquae, Oscillatoria agardhii, and Microcystis aeruginosa in four Swedish lakes. These analyses suggest that while epilimnetic total phosphorus concentration is the principal predictor of their peak biomass, other factors such as station mean depth, water temperature, total nitrogen, and total CO₂ concentration are also important.     

Ethics and biodiversity offsetting

Biodiversity offsetting is an increasingly applied tool aiming to compensate for environmental damage caused by exploitation projects. Critics, however, raise concerns over the purported effectiveness of offsetting and question the ethical underpinnings and implications of offsetting. These ethical dimensions have largely been overlooked in research, which may lead to offsetting systems that fail to respect the values intended to be safeguarded. To address these dimensions, 5 ethical objections in the scientific literature were identified: offsetting violates nature's intrinsic value; losses of nature cannot be compensated for by human interventions; too little is known to make adequate trades; offsetting impedes virtuous dispositions toward nature; and offsetting has negative justice implications. We examined these objections and arguments against them based on the ethical concepts of intrinsic and instrumental values, anthropocentrism, nonanthropocentrism, and deontological, consequentialist, and virtue-ethical paradigms. Both nonanthropocentric and anthropocentric concerns were expressed in deontological, consequential, and virtue-ethical framings. Objections mostly had a deontological or virtue-ethical basis, whereas counterarguments were based on consequential reasoning, but common ground in practice is often conceivable. Based on our findings, we formulated 10 recommendations for policy makers and 5 questions for practitioners to consider. We propose, for example, that policy makers clarify aims, legislate on no-go areas, and govern the use of multipliers. We suggest that practitioners consider, for instance, how to improve case-specific knowledge and promote learning and stakeholder engagement. We hope these recommendations and questions will encourage further discussion of the ethics of biodiversity offsets and ultimately strengthen the respect for biodiversity and human-welfare values at stake in offsetting projects.