<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>Over the past few decades, Ponto-Caspian gammarids <italic>Pontogammarus robustoides, Obesogammarus crassus</italic> and <italic>Dikerogammarus haemobaphes</italic> have colonized the European inland and coastal brackish waters. Previous experimental studies of <italic>P. robustoides</italic>, <italic>O. crassus</italic> and <italic>D. haemobaphes</italic> indicated that the salinity optimum for the species is about 7 PSU. We examined whether salinities below 5 PSU in the Vistula estuary – the Vistula Lagoon and the Vistula Delta, create a favorable environment and have a positive effect on Ponto-Caspian gammarids. The objective of this work was to determine the population parameters (size structure) and biological indicators (condition) of the studied gammarid species at a low salinity level. Length–weight relationships can be considered as their body condition in the environment. These relationships were calculated for each gammarid species according to the exponential equation y = axb, where: y – wet weight, x – total length, a – intercept, b – slope. The results clearly show responses of Ponto-Caspian gammarids to the low salinity habitat and indicate that such environment provides excellent conditions. The results of analysis show that the condition of gammarids is good. The optimal strategy of the examined alien gammarids may help them to maintain a strong competitive position in the environment and affect the colonization process in non-native waters with low salinity.</p></abstract>

Over the past few decades, Ponto-Caspian gammarids Pontogammarus robustoides, Obesogammarus crassus and Dikerogammarus haemobaphes have colonized the European inland and coastal brackish waters. Previous experimental studies of P. robustoides, O. crassus and D. haemobaphes indicated that the salinity optimum for the species is about 7 PSU. We examined whether salinities below 5 PSU in the Vistula estuary – the Vistula Lagoon and the Vistula Delta, create a favorable environment and have a positive effect on Ponto-Caspian gammarids. The objective of this work was to determine the population parameters (size structure) and biological indicators (condition) of the studied gammarid species at a low salinity level. Length–weight relationships can be considered as their body condition in the environment. These relationships were calculated for each gammarid species according to the exponential equation y = axb, where: y – wet weight, x – total length, a – intercept, b – slope. The results clearly show responses of Ponto-Caspian gammarids to the low salinity habitat and indicate that such environment provides excellent conditions. The results of analysis show that the condition of gammarids is good. The optimal strategy of the examined alien gammarids may help them to maintain a strong competitive position in the environment and affect the colonization process in non-native waters with low salinity.

Size structure and body condition of Ponto-Caspian gammarids in the Vistula estuary (Poland)

Oceanological and Hydrobiological Studies

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Over the past few decades, Ponto-Caspian gammarids Pontogammarus robustoides, Obesogammarus crassus and Dikerogammarus haemobaphes have colonized the European...

Species	N	%	L (mm) ± SD	W (g) ± SD
P. robustoides	374	24	8.55 ± 4.02	0.019 ± 0.047
O. crassus	617	41	5.93 ± 1.82	0.003 ± 0.004
D. haemobaphes	530	35	7.73 ± 2.65	0.012 ± 0.011

Species	Area of occurrence	intercepts (a)	slopes (b)	individuals (n)	Reference
Pontogammarus robustoides	Vistula Lagoon and Delta Europe: Poland (brackish environment)	0.0107	3.1317	374	current study
Obesogammarus crassus		0.0041	3.5461	617
Dikerogammarus haemobaphes		0.141	2.0896	530
Pontogammarus robustoides	Gulf of Gdańsk Europe: Poland (brackish environment)	0.0367	2.852	72	Dobrzycka-Krahel et al. 2016
Obesogammarus crassus Dikerogamarus haemobaphes		0.0069	3.3477	75
Dikerogammarus villosus		0.0033	3.7855	225
		0.0674	2.852	117
Gammarus sp.	Black Sea (brackish environment)	0.0016	2.87	20	Rosati et al. 2012
Gammarus minus	North America (freshwater environment)	0.012	2.74		Basset & Glazier 1995
Gammarus pseudolimnaeus	North America (freshwater environment)	0.0049	3.001	37	Marchant & Hynes 1981
Gammaridae	Mediterranean (transiti onal and waters) Black Sea	0.0046	1.2	20	Rosati et al. 2012

Size structure and body condition of Ponto-Caspian gammarids in the Vistula estuary (Poland)

Article Category: Original research paper

Data publikacji: 14 mar 2019

Zakres stron: 23 - 30

Otrzymano: 27 lut 2018

Przyjęty: 09 lip 2018

DOI: https://doi.org/10.1515/ohs-2019-0003

© 2019 Faculty of Oceanography and Geography, University of Gdańsk, Poland

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure 1

Figure 2

Figure 3

Descriptive statistics of body length (L) and wet weight (W) of gammarid species from the Vistula Lagoon and the Vistula Delta in 2009–2011

Calculated intercepts (a) and slopes (b) in the total length–wet weight relationship regression models y = axb of gammarids from different areas and for different numbers of individuals (n)