River VL 5 Flashcards
Fishes are not monophyletic. How is the term “monophyletic” defined?
Monophyletic refers to a group of organisms that includes a common ancestor and all of its descendants.
OR: A monophyletic group consists of a single evolutionary lineage and all of its branches, forming a complete and exclusive clade within a larger evolutionary tree.
- Skeletal fishes are called…?
- Cartilaginous fish are called…?
- Osteichthyes
- Chondrichthyes
What is an “adipose fin” in the fish order Salmoniformes?
- The adipose fin is a small, fleshy fin found on the backs of certain species of fish, typically located between the dorsal fin and the tail fin.
- It is most commonly observed in salmonids, such as salmon and trout, but can also be present in some other freshwater and marine fish species.
- while the precise function of the adipose fin may vary among species, it is believed to play a role in swimming performance, stability, and possibly ommunication or sensory perception in fish.
Name one fish order/family each: Salmoniformies & Percidae
Salmoniformes (order): salmon, trout (Lachs, Forelle)
Percidae (family): perch, pikeperch, ruffe (Barsch, Zander, Kaulbarsch)
Why is the first dorsal fin of the predatory Percidae fishes spiky and the second dorsal fin soft-rayed?
The spiky first dorsal fin can act as a defensive mechanism against predators by making the fish more difficult to swallow. Additionally, it may assist in stabilizing the fish while swimming, especially in fast-flowing waters.
The soft-rayed second dorsal fin is primarily involved in propulsion and maneuverability. Its flexible rays allow for precise control of movement and fine adjustments in speed and direction.
Name four native species:
- Pike (Hecht)
- Eel (Aal)
- Burbut (Quappe)
- European Catfish (Wels)
Name four non-native species:
- Topmouth Gudgeon - Dachsfisch
- Pumpkinseed - Sonnenbarsch
- Rainbow Trout - Regenbogenforelle
- Striped Bass - Gestreifter Seebarsch
Name the three naturally occurring fish colonizations (natürliche Fischbesiedlung)
- Floodings
- Egg dispersal
- Hurricanes (rare)
Is the term “anthropogenic fish introductions” rather positively or negatively connotated?
The term generally carries a negative connotation. This practice refers to the intentional or unintentional release of fish species into ecosystems where they are not native, often resulting in various ecological, economic, and social issues.
What affects fish biomass as well as fish community composition?
Nutrient level
Where is the nutrient level higher: In deep or in shallow lakes?
Deep lakes have usually a low nutrient level, because the nutrient get “stuck” in the bottom parts of the lake.
Shallow lakes often have high nutrient levels.
Name the temperature zones of a lake, their characteristics and where they occur!
Epilimnion:
* Location: This is the uppermost layer of a lake.
* Characteristics: The epilimnion is the warmest layer due to direct exposure to sunlight. It typically has higher levels of dissolved oxygen because of wind mixing and photosynthesis from aquatic plants and phytoplankton.
Metalimnion (or Thermocline):
* Location: This middle layer lies below the epilimnion and above the hypolimnion.
* Characteristics: The metalimnion is characterized by a rapid decrease in temperature with increasing depth. This layer acts as a barrier to mixing between the warmer water above and the cooler water below.
Hypolimnion:
* Location: This is the deepest layer of the lake.
* Characteristics: The hypolimnion is the coldest layer and typically has lower
levels of dissolved oxygen. It is isolated from surface mixing and sunlight, so it remains relatively stable in temperature.
- During summer, layers are more pronounced in temperate lakes due to thermal stratification.
- In autumn and spring, lakes may undergo “turnover,” where the water mixes, resulting in a more uniform temperature distribution throughout
the lake. - In winter, if the lake is ice-covered, the temperature stratification is inverted, with the coldest water just below the ice and slightly warmer water near the bottom.
Differences between meromictic, monomictic, dimictic and polymictic lakes
Meromictic Lakes:
* Mixing: Do not fully mix.
* Characteristics: Have a stable layer of dense, non-circulating bottom water that remains isolated from the upper layers.
Monomictic Lakes:
* Mixing: Mix once per year.
* Characteristics:
- Cold Monomictic: Ice-covered in winter, mix in summer.
- Warm Monomictic: Stratify in summer, mix in winter.
Dimictic Lakes:
* Mixing: Mix twice per year.
* Characteristics: Stratify in summer and winter, mix during spring and autumn turnover.
Polymictic Lakes:
* Mixing: Mix frequently, often daily.
* Characteristics: Typically shallow with frequent temperature and wind-induced mixing, preventing stable stratification.
Where can brown trouts and ruffes be found in rivers?
Brown trouts are mainly in river headwaters, bacuase they can endure the nutreint- low levels and low temperatures.
Ruffes are rather found in river estuaries; bacuse they rely on high nutreint levels and are adapted to high temperatures.
What is an “umbrella species”?
An umbrella species is a concept in conservation biology where the protection of a single species indirectly benefits a larger number of other species and their habitats within the same ecosystem.
