Size-dependent winter mortality of age-0 pikeperch (Stizostedion lucioperca) in Pärnu Bay, the Baltic Sea

2000 ◽  
Vol 57 (2) ◽  
pp. 451-458 ◽  
Author(s):  
Jyrki Lappalainen ◽  
Vaike Erm ◽  
Jakob Kjellman ◽  
Hannu Lehtonen
Keyword(s):  
Baltic Sea ◽  
Water Temperature ◽  
Ice Cover ◽  
Winter Mortality ◽  
The Baltic Sea ◽  
Size Dependent ◽  
The Baltic ◽  
Stizostedion Lucioperca ◽  
Dependent Mortality

Winter mortality of pikeperch (Stizostedion lucioperca) at age 0 is dependent on size, based on samples collected with trawls during 1961-1994 in Pärnu Bay, Estonia. Mortality increased as mean length of pikeperch in the first autumn decreased. The size-dependent mortality was analysed as correlation between mean lengths at age 0 in autumn and changes in mean lengths between age 1 and age 0. When the varying lengths at age 0 were taken into account, the duration of winter also affected mortality; longer durations of ice cover resulted in less size-dependent winter mortality. Since mean length at age 0 in autumn correlated positively with summer water temperature, winter mortality can be expected to decrease the warmer the summer.

scholarly journals One hundred years of atmospheric and marine observations at Utö Island, the Baltic Sea

2018 ◽  
Author(s):  
Lauri Laakso ◽  
Santtu Mikkonen ◽  
Achim Drebs ◽  
Anu Karjalainen ◽  
Pentti Pirinen ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Temperature ◽  
Sea Water ◽  
Seawater Temperature ◽  
Ice Cover ◽  
Atmospheric Temperature ◽  
Research Station ◽  
The Baltic Sea ◽  
Marine Research ◽  
The Baltic

Abstract. Utö Atmospheric and Marine Research Station is located on Utö Island (59°46’50 N, 21°22’23 E) at the outer edge of the Archipelago Sea, Baltic Sea towards the Baltic Sea Proper. Meteorological observations at the island started in 1881 and vertical profiling of sea water temperature and salinity in 1900. In this study, we analyze long-term changes of atmospheric temperature, cloudiness and sea salinity, temperature and ice cover. Our main dataset consists of 248 367 atmospheric temperature observations, 1632 quality assured vertical seawater temperature and salinity profiles and 8565 ice maps, partly digitized for this project. We also use North Atlantic Oscillation (NAO) and Major Baltic Inflow (MBI) data from the literature as reference variables to our data. Our analysis is based on statistical method utilizing dynamic linear model. The results show an increase in the atmospheric temperature at Utö, but the increase is significantly smaller than on land areas and takes place only since early 1980's, with a rate of 0.4 °C/decade during the last 35 years. We also see an increase on sea water temperatures, especially on the surface, with an increase of 0.3 °C/decade for the last 100 years. In deeper water layers the increase is smaller and influenced by vertical mixing, which is modulated by inflow of saline water from the North Sea and fresh water inflow. Date when air temperature in the spring exceeds +5 °C has become 5 days earlier from the period 1951–1980 to period 1981–2010 and date when sea surface water temperature exceed +4 °C has changed 9 days earlier. Sea ice cover duration at Utö shows a decrease of approximately 50 % during the last 35 years. Based on the combined results, it is possible that the climate at Utö may have changed into a new phase, in which ice do not reduce the local effects of global temperature increase.

Effects of lure type, fish size and water temperature on hooking location and bleeding in northern pike (Esox lucius) angled in the Baltic Sea

2014 ◽  
Vol 157 ◽  
pp. 164-169 ◽  
Author(s):  
M. Stålhammar ◽  
T. Fränstam ◽  
J. Lindström ◽  
J. Höjesjö ◽  
R. Arlinghaus ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Temperature ◽  
Northern Pike ◽  
Esox Lucius ◽  
The Baltic Sea ◽  
Fish Size ◽  
Pike Esox Lucius ◽  
The Baltic

scholarly journals Numerical modelling of thermodynamics and dynamics of sea ice in the Baltic Sea

Ocean Science ◽  
2011 ◽  
Vol 7 (2) ◽  
pp. 257-276 ◽  
Author(s):  
A. Herman ◽  
J. Jedrasik ◽  
M. Kowalewski
Keyword(s):  
Sea Ice ◽  
Baltic Sea ◽  
Air Temperature ◽  
Ice Cover ◽  
Surface Fluxes ◽  
Rate Of Change ◽  
The Baltic Sea ◽  
Ice Dynamics ◽  
Ice Concentration ◽  
The Baltic

Abstract. In this paper, a numerical dynamic-thermo-dynamic sea-ice model for the Baltic Sea is used to analyze the variability of ice conditions in three winter seasons. The modelling results are validated with station (water temperature) and satellite data (ice concentration) as well as by qualitative comparisons with the Swedish Meteorological and Hydrological Institute ice charts. Analysis of the results addresses two major questions. One concerns effects of meteorological forcing on the spatio-temporal distribution of ice concentration in the Baltic. Patterns of correlations between air temperature, wind speed, and ice-covered area are demonstrated to be different in larger, more open sub-basins (e.g., the Bothnian Sea) than in the smaller ones (e.g., the Bothnian Bay). Whereas the correlations with the air temperature are positive in both cases, the influence of wind is pronounced only in large basins, leading to increase/decrease of areas with small/large ice concentrations, respectively. The other question concerns the role of ice dynamics in the evolution of the ice cover. By means of simulations with the dynamic model turned on and off, the ice dynamics is shown to play a crucial role in interactions between the ice and the upper layers of the water column, especially during periods with highly varying wind speeds and directions. In particular, due to the fragmentation of the ice cover and the modified surface fluxes, the ice dynamics influences the rate of change of the total ice volume, in some cases by as much as 1 km3 per day. As opposed to most other numerical studies on the sea-ice in the Baltic Sea, this work concentrates on the short-term variability of the ice cover and its response to the synoptic-scale forcing.

Modeling the impact of reduced sea ice cover in future climate on the Baltic Sea biogeochemistry

2013 ◽  
Vol 40 (1) ◽  
pp. 149-154 ◽  
Author(s):  
K. Eilola ◽  
S. Mårtensson ◽  
H. E. M. Meier
Keyword(s):  
Sea Ice ◽  
Baltic Sea ◽  
Ice Cover ◽  
Future Climate ◽  
The Baltic Sea ◽  
The Baltic ◽  
The Impact

scholarly journals First Application of IFCB High-Frequency Imaging-in-Flow Cytometry to Investigate Bloom-Forming Filamentous Cyanobacteria in the Baltic Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Kaisa Kraft ◽  
Jukka Seppälä ◽  
Heidi Hällfors ◽  
Sanna Suikkanen ◽  
Pasi Ylöstalo ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Wind Speed ◽  
Baltic Sea ◽  
Water Temperature ◽  
High Frequency ◽  
Filamentous Cyanobacteria ◽  
Monitoring Methods ◽  
The Baltic Sea ◽  
Imaging Flow Cytometry ◽  
The Baltic

Cyanobacteria are an important part of phytoplankton communities, however, they are also known for forming massive blooms with potentially deleterious effects on recreational use, human and animal health, and ecosystem functioning. Emerging high-frequency imaging flow cytometry applications, such as Imaging FlowCytobot (IFCB), are crucial in furthering our understanding of the factors driving bloom dynamics, since these applications provide community composition information at frequencies impossible to attain using conventional monitoring methods. However, the proof of applicability of automated imaging applications for studying dynamics of filamentous cyanobacteria is still scarce. In this study we present the first results of IFCB applied to a Baltic Sea cyanobacterial bloom community using a continuous flow-through setup. Our main aim was to demonstrate the pros and cons of the IFCB in identifying filamentous cyanobacterial taxa and in estimating their biomass. Selected environmental parameters (water temperature, wind speed and salinity) were included, in order to demonstrate the dynamics of the system the cyanobacteria occur in and the possibilities for analyzing high-frequency phytoplankton observations against changes in the environment. In order to compare the IFCB results with conventional monitoring methods, filamentous cyanobacteria were enumerated from water samples using light microscopical analysis. Two common bloom forming filamentous cyanobacteria in the Baltic Sea, Aphanizomenon flosaquae and Dolichospermum spp. dominated the bloom, followed by an increase in Oscillatoriales abundance. The IFCB results compared well with the results of the light microscopical analysis, especially in the case of Dolichospermum. Aphanizomenon biomass varied slightly between the methods and the Oscillatoriales results deviated the most. Bloom formation was initiated as water temperature increased to over 15°C and terminated as the wind speed increased, dispersing the bloom. Community shifts were closely related to movements of the water mass. We demonstrate how using a high-frequency imaging flow cytometry application can help understand the development of cyanobacteria summer blooms.

scholarly journals CLASSIFYING THE ICE SEASONS 1982-2016 USING THE WEIGHTED ICE DAYS NUMBER AS A NEW WINTER SEVERITY CHARACTERISTIC

2017 ◽  
Vol 5 ◽  
pp. 49-56 ◽  
Author(s):  
Jevgeni Rjazin ◽  
Victor Alari ◽  
Ove Pärn
Keyword(s):  
Baltic Sea ◽  
Ice Cover ◽  
The Baltic Sea ◽  
Concentration Data ◽  
Temporal Dimension ◽  
Ice Concentration ◽  
Long Time ◽  
Ice Conditions ◽  
The Baltic ◽  
Severity Degree

Sea ice is a key climate factor and it restricts considerably the winter navigation in severe seasons on the Baltic Sea. So determining ice conditions severity and describing ice cover behavior at severe seasons are necessary. The ice seasons severity degree is studied at the years 1982 to 2016. A new integrative characteristic named the weighted ice days number of the season is introduced to determine the ice season severity. The ice concentration data on the Baltic Sea published in the European Copernicus Programme are used to calculate the maximal ice extent and the weighted ice days number of the seasons. Both the ice season severity characteristics are used to classify the winters with respect of severity. The ice seasons 1981/82, 1984/85, 1985/86, 1986/87, 1995/96 and 2002/03 are classified as severe by the weighted ice days number. Only three seasons of this list are severe by both the criteria. We interpret this coincidence as the evidence of enough-during extensive ice cover in these three seasons. In the winter 2010/11 ice cover extended widely for some time, but did not last longer. At 2002/03 and a few other ice seasons the Baltic Sea was ice-covered in moderate extent, but the ice cover stayed long time. For 11 winters (32 % of the period) the relational weighted ice days number differs considerably (> 10 %) from the relational maximal ice extent. These winters yield one third of the studied ice seasons. Statistically every 6th winter is severe by the weighted ice days number whereas only statistically every 8th winter is severe by the maximal ice extent on the Baltic. Hence there are more intrinsically severe seasons than the maximal ice extent gives. The maximal ice extent fails to account with the ice cover durability. The weighted ice days number enables to describe the ice cover behavior more representatively. Using the weighted ice days number adds the temporal dimension to the ice season severity study.

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