Q.44 Stenohaline species can tolerate:
Correct Answer: (2) Narrow range of salinity
Stenohaline species are aquatic organisms, typically fish or invertebrates, that thrive only in stable salinity conditions and face osmotic stress if salt levels fluctuate significantly.
Option Analysis
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(1) Narrow range of temperature: Incorrect. Tolerance for narrow temperature ranges defines stenothermal species, not stenohaline ones, which specifically relate to salinity.
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(2) Narrow range of salinity: Correct. These species survive only within a limited salinity spectrum, such as freshwater fish like goldfish dying in high-salt ocean water or marine fish like haddock failing in low-salinity freshwater.
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(3) Wide range of temperature: Incorrect. Wide temperature tolerance describes eurythermal species; stenohaline refers solely to salinity limits.
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(4) Wide range of salinity: Incorrect. Wide salinity tolerance defines euryhaline species, like salmon migrating between rivers and seas, unlike stenohaline’s narrow adaptation.
Stenohaline species can tolerate only a narrow range of salinity, making them highly specialized for stable aquatic environments like freshwater rivers or open oceans. This adaptation highlights key concepts in osmoregulation and ecology, vital for biology exams such as GATE Life Sciences.
Definition and Key Characteristics
Stenohaline species, derived from “steno” (narrow) and “haline” (salt), cannot handle wide salinity fluctuations due to limited osmoregulatory mechanisms. They maintain internal salt-water balance suited to either low-salinity freshwater or consistent marine levels, leading to cell damage if exposed otherwise.
Real-World Examples
Common stenohaline species include goldfish (Carassius auratus) in freshwater, which perish in saline conditions, and haddock in marine habitats, intolerant of dilution. These examples illustrate habitat specificity in stenohaline organisms.
Comparison: Stenohaline vs. Euryhaline
| Feature | Stenohaline Species | Euryhaline Species |
|---|---|---|
| Salinity Tolerance | Narrow range only | Wide range (fresh to salt water) |
| Examples | Goldfish, haddock | Salmon, eels |
| Osmoregulation | Minimal energy for stability | High energy for adjustments |
| Habitat Flexibility | Fixed (freshwater or marine) | Variable (estuaries, migrations) |
Ecological Importance
Stenohaline species dominate uniform habitats but face threats from pollution or climate shifts altering salinity, emphasizing conservation needs. Understanding this aids in studying biodiversity and ecosystem resilience.
