scholarly journals Survival probability of Baltic larval cod in relation to spatial overlap patterns with their prey obtained from drift model studies

2005 ◽  
Vol 62 (5) ◽  
pp. 878-885 ◽  
Author(s):  
H-H. Hinrichsen ◽  
J.O. Schmidt ◽  
C. Petereit ◽  
C. Möllmann
Keyword(s):  
Three Dimensional ◽  
Growth And Survival ◽  
Predator Prey ◽  
Spatial Overlap ◽  
Model Studies ◽  
Hatching Time ◽  
Drift Model ◽  
The Baltic ◽  
Prey Overlap ◽  
Baltic Cod

Abstract Temporal mismatch between the occurrence of larvae and their prey potentially affects the spatial overlap and thus the contact rates between predator and prey. This might have important consequences for growth and survival. We performed a case study investigating the influence of circulation patterns on the overlap of Baltic cod larvae with their prey. A three-dimensional hydrodynamic model was used to analyse spatio-temporally resolved drift patterns of larval Baltic cod. A coefficient of overlap between modelled larval and idealized prey distributions indicated the probability of predator–prey overlap, dependent on the hatching time of cod larvae. By performing model runs for the years 1979–1998 investigated the intra- and interannual variability of potential spatial overlap between predator and prey. Assuming uniform prey distributions, we generally found the overlap to have decreased since the mid-1980s, but with the highest variability during the 1990s. Seasonally, predator–prey overlap on the Baltic cod spawning grounds was highest in summer and lowest at the end of the cod spawning season. Horizontally variable prey distributions generally resulted in decreased overlap coefficients. Finally, we related variations in overlap patterns to the variability of Baltic cod recruitment success.

Operational Model and its Validation with Drift Tests in Water Areas Around the Baltic Sea

1994 ◽  
Vol 29 (2-3) ◽  
pp. 293-308
Author(s):  
J. Koponen ◽  
M. Virtanen ◽  
H. Vepsä ◽  
E. Alasaarela
Keyword(s):  
Three Dimensional ◽  
Fast Response ◽  
Velocity Measurements ◽  
Short Term ◽  
Large Lakes ◽  
Operational Model ◽  
Water Currents ◽  
Emergency Situations ◽  
Sensitivity Tests ◽  
The Baltic

Abstract Three-dimensional (3-D) mathematical models of water currents, transport, mixing, reaction kinetic, and interactions with bottom and air have been used in Finland regularly since 1982 and applied to about 40 cases in large lakes, inland seas and their coastal waters. In each case, model validity has been carefully tested with available flow velocity measurements, tracer studies and water quality observations. For operational use, i.e., for spill combatting and sea rescue, the models need fast response, proven validity and illustrative visualization. In 1987-90, validated models were implemented for operational use at five sea areas along the Finnish coast. Further validation was obtained in model applications from nine documented or arranged cases and from seven emergency situations. Sensitivity tests supplement short-term validation. In the Bothnian Sea, it was nescessary to start the calculation of water currents three days prior to the start of the experiment to reduce initial inaccuracies and to make the coastal transport estimates meaningful.

Three-dimensional predator–prey interactions: a computer simulation of bird flocks and aircraft

1986 ◽  
Vol 64 (11) ◽  
pp. 2624-2633 ◽  
Author(s):  
Peter F. Major ◽  
Lawrence M. Dill ◽  
David M. Eaves
Keyword(s):  
Computer Simulation ◽  
Prey Species ◽  
Three Dimensional ◽  
Aircraft Engine ◽  
Aquatic Environments ◽  
Aircraft Engines ◽  
Predator Prey ◽  
Simulation Techniques ◽  
Computer Simulation Techniques ◽  
Individual Prey

Three-dimensional interactions between grouped aerial predators (frontal discs of aircraft engines), either linearly arrayed or clustered, and flocks of small birds were studied using interactive computer simulation techniques. Each predator modelled was orders of magnitude larger than an individual prey, but the prey flock was larger than each predator. Expected numbers of individual prey captured from flocks were determined for various predator speeds and trajectories, flock–predator initial distances and angles, and flock sizes, shapes, densities, trajectories, and speeds. Generally, larger predators and clustered predators caught more prey. The simulation techniques employed in this study may also prove useful in studies of predator–prey interactions between schools or swarms of small aquatic prey species and their much larger vertebrate predators, such as mysticete cetaceans.The study also provides a method to study problems associated with turbine aircraft engine damage caused by the ingestion of small flocking birds, as well as net sampling of organisms in open aquatic environments.

Remarks on marine and continental biogeography: an areographical viewpoint

1994 ◽  
Vol 343 (1303) ◽  
pp. 71-78 ◽  
Keyword(s):  
Species Richness ◽  
Baltic Sea ◽  
Three Dimensional ◽  
Wide Spread ◽  
The Baltic Sea ◽  
Biogeographical Regions ◽  
The Baltic ◽  
The Way

Differences and similarities in the way marine and continental organisms occupy space are briefly reviewed. Among them, the ‘peninsula effect’ (the decline of species richness with distance from the source) is compared with the ‘bay effect’. Two cases, corals in Mochima Bay, Venezuela and fishes in the Baltic Sea, are presented as examples. The facts that the world’s oceans are larger, continuous and three-dimensional, with fewer evident geographical barriers than there are on land, explain why marine biogeographical regions are less welldefined and geographical ranges of marine taxa more wide-spread. I his generalization has, however, been questioned following recent findings of extremely rich and highly endemic benthic faunas. This problem is discussed using an index of cosmopolitanism to compare terrestrial and marine biotas.

Improving selectivity of the Baltic cod pelagic trawl fishery: Experiments to assess the next step

2010 ◽  
Vol 103 (1-3) ◽  
pp. 40-47 ◽  
Author(s):  
Niels Madsen ◽  
Vesa Tschernij ◽  
Renè Holst
Keyword(s):  
Trawl Fishery ◽  
The Baltic ◽  
Baltic Cod

A PRELIMINARY REPORT ON MODEL STUDIES OF MAGNETIC ANOMALIES OF THREE‐DIMENSIONAL BODIES

Geophysics ◽  
1956 ◽  
Vol 21 (3) ◽  
pp. 794-814 ◽  
Author(s):  
Isidore Zietz ◽  
Roland G. Henderson
Keyword(s):  
Magnetic Fields ◽  
Rapid Method ◽  
Preliminary Report ◽  
Three Dimensional ◽  
Magnetic Anomalies ◽  
Constant Thickness ◽  
Laboratory Methods ◽  
Model Experiments ◽  
Model Studies ◽  
Different Depths

Model experiments were made to devise a rapid method for calculating magnetic anomalies of three‐dimensional structures. The magnetic fields of the models were determined using the equipment at the Naval Ordnance Laboratory, White Oaks, Md. An irregularly shaped mass was approximated by an array of prismatic rectangular slabs of constant thickness and varying horizontal dimensions. Contoured maps are being prepared for these magnetic models at different depths and for several magnetic inclinations. The fields of these three‐dimensional structures are obtained by super‐imposing the appropriate contoured maps and adding numerically the effects at each point. The equipment and laboratory methods are described. Theoretical and practical examples are given.

scholarly journals Thermomechanical modelling of the Scandinavian ice sheet: implications for ice-stream formation

1999 ◽  
Vol 28 ◽  
pp. 83-89 ◽  
Author(s):  
A. J. Payne ◽  
D.J. Baldwin
Keyword(s):  
Three Dimensional ◽  
Ice Sheet ◽  
Ice Streams ◽  
Ice Flow ◽  
Low Viscosity ◽  
Ice Stream ◽  
Scandinavian Ice Sheet ◽  
The Baltic ◽  
Stream Formation ◽  
Initial Results

AbstractThis work attempts to explain the fan-like landform assemblages observed in satellite images of the area covered by the former Scandinavian ice sheet (SIS). These assemblages have been interpreted as evidence of large ice streams within the SIS. If this interpretation is correct, then it calls into doubt current theories on the formation of ice streams. These theories regard soft sediment and topographic troughs as being the key determinants of ice-stream location. Neither can be used to explain the existence of ice streams on the flat, hard-rock area of the Baltic Shield. Initial results from a three-dimensional, thermomechanical ice-sheet model indicate that interactions between ice flow, form and temperature can create patterns similar to those mentioned above. The model uses a realistic, 20 km resolution gridded topography and a simple parameterization of accumulation and ablation. It produces patterns of maximum ice-sheet extent, which are similar to those reconstructed from the area’s glacial geomorphology. Flow in the maximum, equilibrium ice sheet is dominated by wedges of warm, low-viscosity, fast-flowing ice. These are separated by areas of cold, slow-flowing ice. This patterning appears to develop spontaneously as the modelled ice sheet grows.

scholarly journals Deoxygenation impacts on Baltic Sea cod: Dramatic declines in ecosystem services of an iconic keystone predator

AMBIO ◽  
2021 ◽  
Author(s):  
Alessandro Orio ◽  
Yvette Heimbrand ◽  
Karin Limburg
Keyword(s):  
Ecosystem Services ◽  
Baltic Sea ◽  
Gadus Morhua ◽  
Generalized Additive Model ◽  
Additive Model ◽  
Maximum Length ◽  
The Baltic Sea ◽  
Hypoxic Zone ◽  
The Baltic ◽  
Baltic Cod

AbstractThe intensified expansion of the Baltic Sea’s hypoxic zone has been proposed as one reason for the current poor status of cod (Gadus morhua) in the Baltic Sea, with repercussions throughout the food web and on ecosystem services. We examined the links between increased hypoxic areas and the decline in maximum length of Baltic cod, a demographic proxy for services generation. We analysed the effect of different predictors on maximum length of Baltic cod during 1978–2014 using a generalized additive model. The extent of minimally suitable areas for cod (oxygen concentration ≥ 1 ml l−1) is the most important predictor of decreased cod maximum length. We also show, with simulations, the potential for Baltic cod to increase its maximum length if hypoxic areal extent is reduced to levels comparable to the beginning of the 1990s. We discuss our findings in relation to ecosystem services affected by the decrease of cod maximum length.

scholarly journals Factors affecting rule compliance with mesh size regulations in the Baltic cod trawl fishery

2007 ◽  
Vol 64 (8) ◽  
pp. 1603-1606 ◽  
Author(s):  
Petri Suuronen ◽  
Vesa Tschernij ◽  
Pekka Jounela ◽  
Daniel Valentinsson ◽  
P-O. Larsson
Keyword(s):  
Gadus Morhua ◽  
Management Practice ◽  
Mesh Size ◽  
Factors Affecting ◽  
Trawl Fishery ◽  
Management Measures ◽  
Gradual Introduction ◽  
Minimum Landing Size ◽  
The Baltic ◽  
Baltic Cod

Abstract Suuronen, P., Tschernij, V., Jounela, P., Valentinsson, D., and Larsson, P-O. 2007. Factors affecting rule compiance with mesh size regulations in the Baltic cod trawl fishery. – ICES Journal of Marine Science, 64: 1603–1606. In this study, we evaluate the efficiency and applicability of a series of gear-based management measures, enforced since 1990, whose purpose was to improve size selectivity in the trawl fishery for Baltic cod (Gadus morhua). In general, our study revealed that these measures had no marked effect on the capture and discard of young cod. Legal and illegal manipulation of selective codends was widespread. The adoption of a codend design that offered a modest increase in selectivity, but had a good match with the legislated minimum landing size (MLS), led to greater compliance, demonstrating that a mismatch between MLS and selectivity should be avoided. It was also obvious that, generally, the fishing industry did not tolerate large short-term losses. Our evaluation is that overly ambitious rules will be circumvented, and frequent and incoherent changes in the regulations represent bad management practice. A gradual introduction of restrictions and participation by fishers in the decision-making process will increase compliance.

scholarly journals An Evaluation and Implementation of the Regional Coupled Ice-Ocean Model of the Baltic Sea

2017 ◽  
Author(s):  
Jaromir Jakacki ◽  
Sebastian Meler
Keyword(s):  
Baltic Sea ◽  
Three Dimensional ◽  
Coupled Model ◽  
Horizontal Resolution ◽  
Ocean Model ◽  
System Model ◽  
The Baltic Sea ◽  
Community Earth System Model ◽  
The Baltic ◽  
Ice Model

Abstract. A three dimensional, regional coupled ice-ocean model based on the open-source Community Earth System Model has been developed and implemented for the Baltic Sea. The model consists of 66 vertical levels and has a horizontal resolution of approx. 2.3 km. The paper focuses on sea ice component results but the main changes have been introduced in the ocean part of the coupled model. The hydrodynamic part, being one of the most important components, has been also presented and validated. The ice model results were validated against the radar and satellite data, and the method of validation based on probability was introduced. In the last two decades satellite and model results show an increase in the ice extent over the whole Baltic Sea, which is an evidence of a negative trend in air temperature in recent decades and increasing of winter discharge from the catchment area.

Sign in / Sign up

Export Citation Format

Share Document