(1 - 2 of 2)
- Spatial assessment of fin whale hotspots and their association with krill within an important Antarctic feeding and fishing ground
- Fin whale (Balaenoptera physalus quoyi) habitat use and its relationship to environmental conditions are generally unknown in the Southern Ocean, presenting challenges for predicting their seasonal occurrence and potential effects of fishing pressure and climate change on this endangered species. Using biological data collected during 14 shipboard surveys off the northern Antarctic Peninsula and oceanographic data from satellite remote sensing, we mapped the distribution of fin whale hotspots, Antarctic krill abundance (biomass from acoustics, concentrations from nets) and ocean conditions during mid- and late-summer to investigate the environmental determinants of whale hotspots. Generalized additive models (GAM) were used to test the hypothesis that intra-seasonal changes in fin whale hotspot distribution relate to sea surface temperature (SST), krill abundance and eddy kinetic energy (EKE). More whale hotspots (sightings and individuals) are observed during late- than mid-summer surveys. During mid-summer, hotspots occurred near Elephant Island while in late-summer they were distributed throughout the slope region in proximity to the mean location of the southern Antarctic Circumpolar Current Front. The spatial mean of EKE did not differ between mid- and late-summer surveys, but the spatial mean of SST was significantly warmer during late-summer. The GAM for mid-summer indicates that fin whale hotspots were positively related to SST, EKE and acoustically determined krill biomass. The GAM for late-summer indicates the hotspots were negatively related to net-based krill abundance and positively related to acoustic krill biomass and EKE. This study is important because environmental determinants of fin whale hotspots may be used as reference points for implementing future conservation plans for their recovering populations. © 2014 Springer-Verlag Berlin Heidelberg.
- Santora, Schroeder, Loeb
- How many organisms are in ballast water discharge?: A framework for validating and selecting compliance monitoring tools
- As regulations governing the discharge of living organisms in ships' ballast water enter into force, tools to rapidly and easily measure compliance with the discharge standards will be essential. To assess, validate, and select compliance tools, a framework-consisting of three parts-is presented: proof-of-concept, validation and verification, and final selection stages. Next, a case study describing the proof-of-concept stage is discussed. Specifically, variable fluorescence was evaluated as an approach for determining compliance with the discharge standard for living organisms ≥10. μm and <50. μm (typically protists). Preliminary laboratory experiments were conducted, which were followed by an expert workshop to gauge the feasibility of this approach and propose hypothetical thresholds indicating when the discharge standard is undoubtedly exceeded. Subsequently, field trials were conducted to assess this approach and recommended thresholds. All results were favorable, indicating the validation and verification stages are merited to further evaluate fluorometers as compliance monitoring tools. © 2014.
- Drake, Tamburri, First, Smith, Johengen