The Quagga mussel (Dreissena bugensis rostriformis) is a non-indigenous species that has been recorded in Germany for the first time in the Main river, east of Würzburg in 2007 (VAN
DER VELDE & PLATVOET 2007). In October 2007 the Quagga mussel has been recorded at several harbors of the upper Rhine as in the Rheinhafen Karlsruhe, the Ölhafen and the
Industriehafen Mannheim (MARTENS et al. 2007), latter being the locality were samples were taken for this study. D. rostriformis bugensis is closely related to the Zebra mussel (Dreissena polymorpha), which has been recorded in the upper Rhine close to Mannheim around 1840
(REY et al. 2004).
Both species are so called “invasive species” defining them as animals, which “have entered an environment after 1492 (beginning of modern times), that has not been accessible before, to establish new potential populations. This progress happens intended or unintended with direct or indirect involvement of human being” (own translation from German; KINZELBACH 1996) Invasive species are found in many various fauna groups and they often differ in their invasive strategy. D. polymorpha and D. bugensis are both examples of r – strategy;
animal groups with a high reproductive potential, which are usually undemanding generalists (REY et al. 2004).
The origin of the Zebra and the Quagga mussel is the northwestern part of the Black Sea and some estuaries (ORLOVA et al. 2004, VAN DER VELDE & PLATVOET 2007). The natural dispersal of Dreissenidae happens mainly by larval drift enhanced by currents, or water birds which spread larvae attached to them. But human influence allows these species to cope with larger distances and to cross their natural barriers. Veliger larvae of Dreissenidae can settle on boats or they are being transported within the ballast water of ships, allowing them to move upstream. So shipping has been identified as the primary dispersal mechanism for both invasive freshwater Dreissenids (JOHNSON et al. 2001; ORLOVA et al. 2005). There are two main canals connecting the Pontocaspian region with the region of Western Europe. The navigable waterways of the interconnected rivers Dniepr, Prypet, Bug, Vistula, Oder, Rhine
and German canals (Midland canal etc.) constitute a northern invasion route, and the Danube a southern route to western Europe (MÜLLER et al. 2002)
Table of Contents
1. Abstract
2. Introduction
2.1 Ecological and economical damages
2.2 Aim of this study
3. Materials and Methods
3.1 Industriehafen Mannheim
3.2 Method of sampling
3.3 Measurement and identification
3.4 Morphological differences between Zebra and Quagga mussels
4. Results
4.1 Relative abundance of Dreissena polymorpha and Dreissena bugensis
4.2 Population density of Dreissena polymorpha and Dreissena bugensis
4.3 Vertical distribution of Dreissena polymorpha and Dreissena bugensis
5. Discussion
5.1 Methods
5.2 Results
5.2.1 Vertical distribution
5.2.2 Age structure
5.3 Conclusion
6. Didaktische Begründung
6.1 A bilingual project?
6.2 Ideen zur Gestaltung – a bilingual project
6.3 Medienkompetenz
6.4 Biologie und Sprache
Research Objectives and Main Topics
The primary aim of this study is to examine the vertical distribution and relative abundance of the non-indigenous Dreissena bugensis (Quagga mussel) in comparison to the established Dreissena polymorpha (Zebra mussel) within the Industriehafen Mannheim. The research investigates whether the observed distribution patterns provide insights into the initial phase of Quagga mussel settlement and its competitive displacement of the Zebra mussel, while also exploring the didactic potential of this topic for bilingual biology education at the secondary school level.
- Ecological and economic impacts of invasive Dreissenid species.
- Comparative analysis of population density and size-class distribution.
- Morphological identification and environmental adaptations of Quagga and Zebra mussels.
- Didactic integration of invasive species research into bilingual curricula.
- Media literacy and methodological approaches in school-based biological research.
Excerpt from the Book
3.4 Morphological differences between Zebra and Quagga mussels
The Zebra and the Quagga mussel belong to the family of Dreissenidae mussels and have their origin in the Black Sea, Pontocaspian region. The wide variability in coloration and the stripe pattern of both, the Zebra and the Quagga mussel can lead to uncertain identification of the species as long as one is not familiar with the distinguishing shape of the shell. The coloration pattern of both species has a high variability reaching from all black to all cream and brown. Both species also show a pattern of stripes in different kind of variability including smooth stripes, jagged stripes, reminding one of the zebra stripes and single, longitudinal stripes (figure 6 & 7). Quagga mussels show some different stripe patterns and variability of coloration, the characteristic “zebra stripes” are missing (MARTENS et al. 2007). There is one distinguishing pattern consisting of lateral black and white stripes, interrupted by a longitudinal white line ( MAY & MARDSEN 1992).
When viewed in cross-section the ventral margin is flattened, arched or concave and the ventrolateral shoulder is acute, giving D. polymorpha its characteristic triangular shape. This shape indicates the ability of D. polymorpha to be tightly attached to the substrate by its byssal threads. The Quagga mussel is more rounded and flattened and “cants over / capsizes” (figure 7). Its ventral margin is convex with a rounded ventrolateral shoulder (MACKIE & SCHLOESSER 1996). Its byssal gland is at the forefront not centric as with the Zebra mussel. It is helpful to take samples of each species between thumb and index finger; while turning the mussel one can feel the ridges of D. polymorpha.
Summary of Chapters
1. Abstract: Provides an overview of the study, noting the sampling conducted in the Industriehafen Mannheim and the observation that D. bugensis is the dominant species, displacing D. polymorpha.
2. Introduction: Outlines the origins and invasive nature of Dreissenid mussels, discussing their rapid spread via shipping and their classification as r-strategists.
3. Materials and Methods: Describes the sampling location at Industriehafen Mannheim, the collection process using a research vessel, and the morphological identification criteria used for the mussels.
4. Results: Details the findings regarding the relative abundance, population density, and size-class distribution, showing a clear dominance of D. bugensis across the sampled profiles.
5. Discussion: Evaluates the methodology, analyzes the vertical distribution patterns in relation to substrate and depth, and estimates the age structure and initial settlement phase of the Quagga mussel.
6. Didaktische Begründung: Discusses the educational relevance of teaching invasive species in bilingual secondary school settings, emphasizing the development of scientific competencies.
Keywords
Quagga mussel, Zebra mussel, Dreissena bugensis, Dreissena polymorpha, Industriehafen Mannheim, invasive species, vertical distribution, population density, bilingual education, aquatic ecology, biological research, displacement, morphology, environmental impact, r-strategy.
Frequently Asked Questions
What is the core focus of this scientific study?
The study investigates the current population dynamics, specifically the vertical distribution and abundance, of the invasive Quagga mussel compared to the Zebra mussel in the Industriehafen Mannheim harbor basin.
What are the primary thematic areas covered?
The work covers marine biological ecology, the invasive history of Dreissenid species, methods for field sampling in harbor environments, morphological classification, and pedagogical approaches for teaching these topics in bilingual biology classes.
What is the primary goal or research question?
The primary aim is to observe the vertical distribution of adult mussels in relation to their abundance to better understand the initial settlement phases of the Quagga mussel and its displacement of the Zebra mussel.
Which scientific methods are utilized?
The study utilizes field sampling with the research vessel "Max Honsell," depth profiling via sonar and pendulum, physical collection using a hydraulic shovel, and statistical analysis based on size-class categorization.
What is covered in the main body of the work?
The main body comprises a detailed materials and methods section, presentation of results through graphs and schematic profiles, and a critical discussion of findings compared to existing literature from North America and Europe.
Which keywords characterize this paper?
Key terms include Quagga mussel, Zebra mussel, invasive species, vertical distribution, population density, bilingual education, and Dreissena.
How does the Quagga mussel physically differ from the Zebra mussel?
The Quagga mussel is more rounded and flattened and tends to "capsize" when placed on a flat surface, whereas the Zebra mussel has a characteristic triangular shape with an acute ventrolateral shoulder that allows it to attach tightly to substrates.
Why is the Industriehafen Mannheim a significant site for this research?
The harbor serves as an ideal sampling site because it is an inland port with known records of both species, allowing for a concentrated comparative study of a rapidly changing local population.
What conclusion does the author draw regarding the displacement of the Zebra mussel?
The author concludes that D. bugensis has become the dominant species in the harbor and predicts that if the current displacement trend continues, D. polymorpha will become a rare species in the region within a few years.
Why does the author advocate for a bilingual approach to teaching this topic?
The author argues that research on these species is largely published in English, and using these authentic sources in a bilingual project enriches the learning experience and helps students develop both linguistic skills and scientific media literacy.
- Citation du texte
- Stephan Drescher (Auteur), 2008, The Vertical Distribution of the Quagga Mussel in Harbours. From Ecological Research to Bilingual Teaching at Secondary Level, Munich, GRIN Verlag, https://www.grin.com/document/284096
