Exploring the dynamics of herring consumption in the Baltic : applications of an energetic model of fish growth

A bioenergetic model was parameterized for herring (Clupea harengus) using information available in the literature. In this model, all components of the energy budget are functions of temperature and fish weight. The model is used to simulate herring growth and consumption in a coastal area of the northern Baltic proper. Simulated seasonal growth curves restrained to fit one weight per age class are similar to observed growth curves, indicating the importance of temperature in determining herring growth rates in the Baltic. Calculated food consumption and conversion efficiencies are compared with other published estimates

What is the impact on fish recruitment of anthropogenic physical and structural habitat change in shallow nearshore areas in temperate systems? A systematic review protocol

Shallow nearshore marine ecosystems are changing at an increasing rate due to a range of human activities such as urbanisation and commercial development. The growing numbers of constructions and other physical and structural alterations of the shoreline often take place in nursery and spawning habitats of many fish and other aquatic species. Several coastal fish populations have seen marked declines in abundance and diversity during the past two decades. A systematic review on the topic would clarify if anthropogenic physical and structural changes of near-shore areas have effects on fish recruitment and which these effects are. Methods: The review will examine how various physical and structural anthropogenic changes of nearshore fish habitats affect fish recruitment. Relevant studies include small- and large-scale field studies in marine and brackish systems or large lakes in temperate regions of the Northern and Southern hemispheres. Relevant studies may be based on comparisons between undisturbed and disturbed areas, before and after disturbance, or both. Relevant outcomes include measures of recruitment defined as abundance of juveniles of nearshore fish communities. Searches will be made for peer-reviewed and grey literature in English, Dutch, Danish, Finnish, German, Swedish and Spanish. All fish species and species groups will be considered in this review. Included relevant studies will be subject to a critical appraisal that will assess study validity. From relevant included studies, we will extract information on study characteristics, measured outcomes, exposure, comparators, effect modifiers and critical appraisal. Data synthesis will contain narrative and summary findings of each included study of sufficient quality. Meta-analysis may be possible in cases where studies report similar types of outcome

Status of the Lake Ontario Food Web in a Changing Ecosystem: the 2003 Lake Ontario Lower Aquatic Food Web Assessment (LOLA)

Understanding stressor impacts on ecological processes in Lake Ontario over the last three decades has resulted from a commitment to long-term binational studies by environmental agencies and their dedicated scientists and support staffs in both Canada and the United States. LOLA was initiated at the request of the United States and Canada Lake Ontario Lakewide Management Plan (LaMP) and the Great Lakes Fishery Commission’s Lake Ontario Committee with the following two goals: 1) assess the status of and 2) develop recommendations for the long-term comprehensive assessment of the Lake Ontario lower aquatic food web. The 2003 LOLA project incorporated seasonal sampling at a large spatial scale, providing the most comprehensive assessment of the status of Lake Ontario’s lower food web since the Lake Ontario Trophic Transfer Program in 1995. Partners from seven government agencies and six universities and colleges participated in the LOLA project. A workshop attended by LaMP representatives, government agencies, and academics was held at Cornell University on November 16-17, 2005. Discussions based on significant findings that were presented at the workshop resulted in seven recommendations for future assessment of the Lake Ontario lower aquatic food web

Heavy nuclei at the end of the cosmic ray spectrum?

We provide an account of the possible acceleration of iron nuclei up to energies $\sim300$ EeV in the nearby, metally-rich starburst galaxy NGC 253. It is suggested that particles can escape from the nuclear region with energies of $\sim10^{15}$ eV and then could be reaccelerated at the terminal shock of the galactic superwind generated by the starburst, avoiding in this way the photodisintegration expected if the nuclei were accelerated in the central region of high photon density. We have also made estimates of the expected arrival spectrum, which displays a strong dependency with the energy cutoff at the source.Comment: Revised version, to appear in Physical Review

Veterans’ civilian employment experiences: Lessons learnt from focus groups

Emerging evidence highlights employment as a key factor influencing the success of transition from military to civilian life. Historically, employment programs have focused on improving skills such as resume writing and interview skills. However, it is likely that employment challenges are more than these practical barriers. Four focus groups with employed and unemployed Gulf War Era II veterans were conducted aimed at moving past a practical perspective by gaining experiential understandings of veterans’ employment. Thematic analysis indicated that the veterans’ employment experiences were best understood temporally in two master themes: pretransition and the divergent experiences of veterans who did and did not plan ahead and living the transition and the veterans’ experiences of employment barriers and facilitators. Further to the two master themes, an underlying thread of the need for self-determination was evident. Interpretation of the results led to the development of recommendations for policy, service provision, and future research

Fish Bioenergetics 4.0: An R‐Based Modeling Application

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141352/1/fsh0586.pd

The extent and variability of storm-induced temperature changes in lakes measured with long-term and high-frequency data

The intensity and frequency of storms are projected to increase in many regions of the world because of climate change. Storms can alter environmental conditions in many ecosystems. In lakes and reservoirs, storms can reduce epilimnetic temperatures from wind-induced mixing with colder hypolimnetic waters, direct precipitation to the lake's surface, and watershed runoff. We analyzed 18 long-term and high-frequency lake datasets from 11 countries to assess the magnitude of wind- vs. rainstorm-induced changes in epilimnetic temperature. We found small day-to-day epilimnetic temperature decreases in response to strong wind and heavy rain during stratified conditions. Day-to-day epilimnetic temperature decreased, on average, by 0.28 degrees C during the strongest windstorms (storm mean daily wind speed among lakes: 6.7 +/- 2.7 m s(-1), 1 SD) and by 0.15 degrees C after the heaviest rainstorms (storm mean daily rainfall: 21.3 +/- 9.0 mm). The largest decreases in epilimnetic temperature were observed >= 2 d after sustained strong wind or heavy rain (top 5(th) percentile of wind and rain events for each lake) in shallow and medium-depth lakes. The smallest decreases occurred in deep lakes. Epilimnetic temperature change from windstorms, but not rainstorms, was negatively correlated with maximum lake depth. However, even the largest storm-induced mean epilimnetic temperature decreases were typicallyPeer reviewe

Rapid and highly variable warming of lake surface waters around the globe

In this first worldwide synthesis of in situ and satellite-derived lake data, we find that lake summer surface water temperatures rose rapidly (global mean = 0.34°C decade−1) between 1985 and 2009. Our analyses show that surface water warming rates are dependent on combinations of climate and local characteristics, rather than just lake location, leading to the counterintuitive result that regional consistency in lake warming is the exception, rather than the rule. The most rapidly warming lakes are widely geographically distributed, and their warming is associated with interactions among different climatic factors—from seasonally ice-covered lakes in areas where temperature and solar radiation are increasing while cloud cover is diminishing (0.72°C decade−1) to ice-free lakes experiencing increases in air temperature and solar radiation (0.53°C decade−1). The pervasive and rapid warming observed here signals the urgent need to incorporate climate impacts into vulnerability assessments and adaptation efforts for lakes.Peer reviewe

Environmental cues and constraints affecting the seasonality of dominant calanoid copepods in brackish, coastal waters: a case study of Acartia, Temora and Eurytemora species in the south-west Baltic

Information on physiological rates and tolerances helps one gain a cause-and-effect understanding of the role that some environmental (bottom–up) factors play in regulating the seasonality and productivity of key species. We combined the results of laboratory experiments on reproductive success and field time series data on adult abundance to explore factors controlling the seasonality of Acartia spp., Eurytemora affinis and Temora longicornis, key copepods of brackish, coastal and temperate environments. Patterns in laboratory and field data were discussed using a metabolic framework that included the effects of ‘controlling’, ‘masking’ and ‘directive’ environmental factors. Over a 5-year period, changes in adult abundance within two south-west Baltic field sites (Kiel Fjord Pier, 54°19′89N, 10°09′06E, 12–21 psu, and North/Baltic Sea Canal NOK, 54°20′45N, 9°57′02E, 4–10 psu) were evaluated with respect to changes in temperature, salinity, day length and chlorophyll a concentration. Acartia spp. dominated the copepod assemblage at both sites (up to 16,764 and 21,771 females m−3 at NOK and Pier) and was 4 to 10 times more abundant than E. affinis (to 2,939 m−3 at NOK) and T. longicornis (to 1,959 m−3 at Pier), respectively. Species-specific salinity tolerance explains differences in adult abundance between sampling sites whereas phenological differences among species are best explained by the influence of species-specific thermal windows and prey requirements supporting survival and egg production. Multiple intrinsic and extrinsic (environmental) factors influence the production of different egg types (normal and resting), regulate life-history strategies and influence match–mismatch dynamics