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Annual, seasonal and spatial differences in the growth rate of Baltic cod larvae and early juveniles in relation to zooplankton biomass fluctuations in 2006-2014 Cover

Annual, seasonal and spatial differences in the growth rate of Baltic cod larvae and early juveniles in relation to zooplankton biomass fluctuations in 2006-2014

Oceanological and Hydrobiological Studies
Volume 52 (2023): Issue 4 (December 2023)
By: Katarzyna Spich and  Dariusz Piotr Fey  
Open Access
|Dec 2023

Figures & Tables

Figure 1

Location of ichthyoplankton and zooplankton sampling stations between 2006 and 2014. Black circles indicate WP-2 stations. Sub-areas of the study area are indicated: BB – Bornholm Basin, yellow points; GB – Gdańsk Basin, red points; and SF – Słupsk Furrow, blue points.
Location of ichthyoplankton and zooplankton sampling stations between 2006 and 2014. Black circles indicate WP-2 stations. Sub-areas of the study area are indicated: BB – Bornholm Basin, yellow points; GB – Gdańsk Basin, red points; and SF – Słupsk Furrow, blue points.

Figure 2

Dependence of SL on larval and juvenile cod age during the 2006-2014 period described by simple linear regression separately for specimens younger and older than 60 d (A); and the same data described by a best-fit 4th order polynomial function with the aim of determining residuals reflecting the growth rates of specific individuals in comparison to the mean for the entire population (B).
Dependence of SL on larval and juvenile cod age during the 2006-2014 period described by simple linear regression separately for specimens younger and older than 60 d (A); and the same data described by a best-fit 4th order polynomial function with the aim of determining residuals reflecting the growth rates of specific individuals in comparison to the mean for the entire population (B).

Figure 3

Median (square), 25 and 75 percentile (box), non-outlier range (whiskers), and mean (diamond) values of the GR index (%) of larval and juvenile cod in the southern Baltic Sea in the 2006-2014 period: differences between seasons (spring and summer).
Median (square), 25 and 75 percentile (box), non-outlier range (whiskers), and mean (diamond) values of the GR index (%) of larval and juvenile cod in the southern Baltic Sea in the 2006-2014 period: differences between seasons (spring and summer).

Figure 4

Median (square), 25 and 75 percentile (box), non-outlier range (whiskers), and mean (diamond) values of the GR index (%) of larval and juvenile cod in the southern Baltic Sea in the 2006-2014 period: differences among geographical areas (Bornholm Basin, BB; Słupsk Furrow, SF; and Gdańsk Basin, GB).
Median (square), 25 and 75 percentile (box), non-outlier range (whiskers), and mean (diamond) values of the GR index (%) of larval and juvenile cod in the southern Baltic Sea in the 2006-2014 period: differences among geographical areas (Bornholm Basin, BB; Słupsk Furrow, SF; and Gdańsk Basin, GB).

Figure 5

Median (square), 25 and 75 percentile (box), non-outlier range (whiskers), and mean (diamond) values of the GR index (%) of larval and juvenile cod in the southern Baltic Sea by year: inter-annual differences (2006–2014). Dotted lines indicate the mean calculated separately for two periods: 2006–2011 and 2012–2014.
Median (square), 25 and 75 percentile (box), non-outlier range (whiskers), and mean (diamond) values of the GR index (%) of larval and juvenile cod in the southern Baltic Sea by year: inter-annual differences (2006–2014). Dotted lines indicate the mean calculated separately for two periods: 2006–2011 and 2012–2014.

Figure 6

Biomass of the dominant zooplankton taxonomic groups in the southern Baltic during the 2006 – 2014 period by size fraction (small zooplankton, NP+C3; large zooplankton, C4+AD) and study season (spring and summer).
Biomass of the dominant zooplankton taxonomic groups in the southern Baltic during the 2006 – 2014 period by size fraction (small zooplankton, NP+C3; large zooplankton, C4+AD) and study season (spring and summer).

Figure 7

Mean biomass of the four zooplankton taxonomic groups (Acartia spp., Pseudocalanus spp., T. longicornis, C. hamatus) in the southern Baltic in the 2006–2014 period by geographical region (Bornholm Basin, BB; Gdańsk Basin, GB; Słupsk Furrow, SF) and size fraction (small zooplankton, NP+C3; large zooplankton, C4+AD).
Mean biomass of the four zooplankton taxonomic groups (Acartia spp., Pseudocalanus spp., T. longicornis, C. hamatus) in the southern Baltic in the 2006–2014 period by geographical region (Bornholm Basin, BB; Gdańsk Basin, GB; Słupsk Furrow, SF) and size fraction (small zooplankton, NP+C3; large zooplankton, C4+AD).

Figure 8

Relative (deviation from the mean) biomass of the four zooplankton taxonomic groups (Acartia spp., Pseudocalanus spp., T. longicornis, C. hamatus) in the 2006-2014 period by geographical region (Bornholm Basin, BB; Gdańsk Basin, GB; Słupsk Furrow, SF), size fraction (small zooplankton, NP+C3; large zooplankton, C4+AD), and season (spring and summer).
Relative (deviation from the mean) biomass of the four zooplankton taxonomic groups (Acartia spp., Pseudocalanus spp., T. longicornis, C. hamatus) in the 2006-2014 period by geographical region (Bornholm Basin, BB; Gdańsk Basin, GB; Słupsk Furrow, SF), size fraction (small zooplankton, NP+C3; large zooplankton, C4+AD), and season (spring and summer).

Figure 9

Long-term temperature variations (means for all stations in a given year) by two water layers (surface layer above the thermocline; deep water layer below the thermocline). (A) spring; (B) summer; T1 – average temperature from surface to thermocline, T2 – average temperature from thermocline to the bottom.
Long-term temperature variations (means for all stations in a given year) by two water layers (surface layer above the thermocline; deep water layer below the thermocline). (A) spring; (B) summer; T1 – average temperature from surface to thermocline, T2 – average temperature from thermocline to the bottom.

S2

Mean growth rates of larval and juvenile cod in the southern Baltic in the 2006-2014 period. Each point represents the values of an individual specimen.
Mean growth rates of larval and juvenile cod in the southern Baltic in the 2006-2014 period. Each point represents the values of an individual specimen.

S3

Residuals of the SL-at-age relationship described with 4th order polynomial function.
Residuals of the SL-at-age relationship described with 4th order polynomial function.

S4

Geographical differences in the GR index (%) along longitude and latitude in spring and summer.
Geographical differences in the GR index (%) along longitude and latitude in spring and summer.

S5

The relationships between the GR index and zooplankton biomass in spring and summer. Mean values for station are presented. Green squares indicate p < 0.05.
The relationships between the GR index and zooplankton biomass in spring and summer. Mean values for station are presented. Green squares indicate p < 0.05.

S6

The relationships between the zooplankton biomass and surface water temperature in spring and summer. Mean values for stations are presented. Green squares indicate p < 0.05.
The relationships between the zooplankton biomass and surface water temperature in spring and summer. Mean values for stations are presented. Green squares indicate p < 0.05.

S7

The relationships between the GR index and surface water temperature in spring and summer. Mean values for station are presented.
The relationships between the GR index and surface water temperature in spring and summer. Mean values for station are presented.

An overview of the most important parameters (SL in mm and age in d) of the larval and juvenile cod caught in the 2006-2014 period, the number of individuals caught in the spring (April-May-June) and summer (July-August), and in the other sub-areas of the Baltic Sea (BB – Bornholm Basin; GB – Gdańsk Basin; and SF – Słupsk Furrow)_

YearAreaSpringSummer
SL (mm)Age (days)nSL (mm)Age (days)n
2006BB--09.9-39.214.5-105.595
GB--010.9-27.934.0-109.09
SF--08.5-25.226.0-76.021
2007BB--06.3-18.94.0-70.522
GB--0--0
SF--0--0
2008BB4.9-9.32.0 - 15.084.5-28.12.0-100.551
GB--07.5-23.910.0-86.07
SF4.1-4.52.0-3.026.8-31.710.0-136.012
2009BB10.525.51--0
GB--011.1-26.126.5-74.57
SF--021.1-22.765.5-67.52
2010BB--08.5-14.19.0-40.06
GB--012.7-15.947.5-68.06
SF--07.9-13.915.0-46.55
2011BB33.1131.016.3-24.14.0-91.568
GB--0--0
SF--08.9-16.95.0-62.011
2012BB5.3-14.54.0-56.0326.7-18.98.0-80.542
GB4.9-8.92.5-20.0512.752.01
SF5.5-5.97.0-10.027.5-9.315.0-45.08
2013BB4.9-9.94.0-24.0267.1-14.15.0-39.08
GB5.7-6.98.0-15.04--0
SF4.9-8.16.0-10.0813.115.01
2014BB4.5-7.92.0-20.0118.1-12.122.0-32.02
GB5.9-10.115.0-33.048.7-10.124.0-40.03
SF--0--0

The results of correlation analysis (r values) for the relationships between the GR index and environmental variables (zooplankton biomass and water temperature) and between zooplankton biomass and surface temperature_ Mean annual values were used for each of the relationships_ The analysis covers the period between 2006 and 2014 (spring n = 34; summer n = 60)_ Pseudocalanus spp_ (P), Temora longicornis (T), Acartia spp_ (A), Centropages hamatus (C) and temperature (T), and all four zooplankton groups together (All)_ Significance levels:

SeasonParameterZooplankton biomassT (oC)
AllPTAC
SpringNP+C1
%GR_cod0.42*0.290.40*0.240.44*0.15
T (oC)0.37*0.46*0.150.040.01
C4+AD
%GR_cod0.060.39*0.030.160.150.15
T (oC)0.58*0.150.62*0.54*0.59*
SummerNP+C1
%GR_cod0.020.010.040.050.080.13
T (oC)0.35*0.27*0.28*0.090.38*
C4+AD
%GR_cod0.220.170.140.170.130.13
T (oC)0.29*0.040.35*0.000.38*

The list of all cruises conducted during research period 2006-2014 and an inventory of collected samples_

NoYearStartStopNo of zooplankton samplesNo of ichthyoplankton samples
1.200618.04.200628.04.2006220
2.26.06.200607.07.20062225
3.14.08.200625.08.20061828
4.200714.06.200725.06.2007260
5.16.08.200727.08.20072015
6.200817.04.200828.04.2008227
7.22.08.200831.08.20082433
8.200929.04.200909.05.2009221
9.14.08.200925.08.2009164
10.201004.05.201014.05.2010180
11.16.08.201031.08.20101812
12.201105.05.201113.05.2011141
13.18.08.201128.08.20112027
14.201212.05.201216.05.20122019
15.20.08.201227.08.20122021
16.201310.05.201320.05.20132225
17.14.08.201324.08.20132010
18.201416.06.201423.06.20141810
19.18.08.201423.08.2014-5
DOI: https://doi.org/10.26881/oahs-2023.4.02 | Journal eISSN: 1897-3191 | Journal ISSN: 1730-413X
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Language: English
Page range: 399 - 419
Submitted on: Jul 30, 2023
Accepted on: Nov 15, 2023
Published on: Dec 31, 2023
Published by: University of Gdańsk
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year
Keywords:
Gadus morhua,
growth rate,
fish,
early life stages,
zooplankton,
otoliths,
microincrements
Related subjects:
Chemistry,
Chemistry, other,
Geosciences,
Geosciences, other,
Life sciences,
Life sciences, other

© 2023 Katarzyna Spich, Dariusz Piotr Fey, published by University of Gdańsk
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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