Steeper size spectra with decreasing phytoplankton biomass indicate strong trophic amplification and future fish declines

Under climate change, model ensembles suggest that declines in phytoplankton biomass amplify into greater reductions at higher trophic levels, with serious implications for fisheries and carbon storage. However, the extent and mechanisms of this trophic amplification vary greatly among models, and validation is problematic. In situ size spectra offer a novel alternative, comparing biomass of small and larger organisms to quantify the net efficiency of energy transfer through natural food webs that are already challenged with multiple climate change stressors. Our global compilation of pelagic size spectrum slopes supports trophic amplification empirically, independently from model simulations. Thus, even a modest (16%) decline in phytoplankton this century would magnify into a 38% decline in supportable biomass of fish within the intensively-fished mid-latitude ocean. We also show that this amplification stems not from thermal controls on consumers, but mainly from temperature or nutrient controls that structure the phytoplankton baseline of the food web. The lack of evidence for direct thermal effects on size structure contrasts with most current thinking, based often on more acute stress experiments or shorter-timescale responses. Our synthesis of size spectra integrates these short-term dynamics, revealing the net efficiency of food webs acclimating and adapting to climatic stressors

Steeper size spectra with decreasing phytoplankton biomass indicate strong trophic amplification and future fish declines

Under climate change, model ensembles suggest that declines in phyto�plankton biomass amplify into greater reductions at higher trophic levels, with serious implications for fisheries and carbon storage. However, the extent and mechanisms of this trophic amplification vary greatly among models, and validation is problematic. In situ size spectra offer a novel alternative, com�paring biomass of small and larger organisms to quantify the net efficiency of energy transfer through natural food webs that are already challenged with multiple climate change stressors. Our global compilation of pelagic size spectrum slopes supports trophic amplification empirically, independently from model simulations. Thus, even a modest (16%) decline in phytoplankton this century would magnify into a 38% decline in supportable biomass of fish within the intensively-fished mid-latitude ocean. We also show that this amplification stems not from thermal controls on consumers, but mainly from temperature or nutrient controls that structure the phytoplankton baseline of the food web. The lack of evidence for direct thermal effects on size structure contrasts with most current thinking, based often on more acute stress experiments or shorter-timescale responses. Our synthesis of size spectra integrates these short-term dynamics, revealing the net efficiency of food webs acclimating and adapting to climatic stressor

‘This is a beautiful school.’ ‘This school is useless!!’ Explaining disengagement in a Greek vocational school through the examination of teacher ideologies

This multi-method case study of a Greek vocational school explored teachers’ culture (including beliefs about education, teachers’ role, and students’ nature) using the concept of pupil control ideology to explain problems of disengagement and low morale among staff and students, as well as tensions in relationships. A prominent custodial culture was identified in the school using a functional/apolitical pedagogy to transmit ‘legitimate’ knowledge to students whose working-class background did not produce desired outcomes. This generated deficit views of students, teachers’ sympathy, and a seemingly caring school ethos which was, nevertheless, oppressive. Students’ failings were naturalised and vocational education misinterpreted as merely a streaming device in a system honouring academic achievement and middle-class ways. Teachers were blind to these cultural subtleties, believing they acted ‘rationally’ and altruistically. A humanistic subculture emphasising student empowerment and social transformation consisted of a minority of teachers and was rather marginalised. This disallowed meaningful dialogue and the identification of an alternative rationale for the sector, generating strong feelings of futility. Positive change in this school necessitated the deconstruction and (subsequent) reconstruction of custodial teachers’ world views as embedded in their practice. © 2016 Association for Research in Post-Compulsory Education (ARPCE)

Length–Weight relations of 22 fish species from the littoral zone of the Eastern Ionian Sea, Greece

Length–weight relations are presented for 22 fish species caught in the littoral zone of the eastern Ionian Sea. Mean values of b ranged from 2.58 to 3.43. For Greek waters no information regarding the LWR existed for 2 of the recorded species. This is the first study on the LWR for species of the littoral zone of the eastern Ionian Sea which may be helpful in future fisheries studies in this area

The “MetaCopepod” project: Designing an integrated DNA metabarcoding and image analysis approach to study and monitor the diversity of zooplanktonic copepods and cladocerans in the Mediterranean Sea

The timely and accurate analysis of marine zooplankton diversity is a challenge in ecological and monitoring studies. Morphology-based identification of taxa, which requires taxonomy experts, is time consuming and cannot provide accurate resolution at species level in several cases (e.g. immature stages, cryptic species, broken specimens). The “MetaCopepod” project is aimed at overcoming these limitations by developing a high-throughput and cost effective methodology that integrates DNA metabarcoding and image analysis. Utilizing the accuracy of DNA metabarcoding in species recognition and the quantitative results of image analysis, zooplankton diversity (mainly of copepods and cladocerans) is assessed both qualitatively (species' composition) and quantitatively (abundance, biomass and size-distribution). To achieve this goal, bulk zooplankton samples are first scanned and analyzed with ZooImage and then massively sequenced for a selected fragment of the mitochondrial 16S rRNA gene. Through a bioinformatic pipeline, sequences are compared to a reference genetic database, constructed within the project, and identified at species- level. The methodology was calibrated by using both mock and taxonomically identified samples and demonstrated on samples collected monthly from monitoring stations across the Mediterranean Sea. It is currently optimized for higher integration and accuracy and is expected to become a powerful tool for monitoring zooplankton in the long term and for early warning of bioinvasions and other ecosystem change