Scientific Foundation & Data Sources

Global Acoustic Pollution Research

Silent Pollution is grounded in peer-reviewed scientific research on underwater acoustic ecology.
This section documents the global research context and our specific sources.

FOUNDATIONAL RESEARCH PAPERS

Hildebrand, J. A. (2009)

"Anthropogenic and Natural Sources of Ambient Noise in the Ocean"
Marine Ecology Progress Series, Vol. 395, pp. 5-20
> Shipping contribution to ocean ambient noise has increased by as much as 12 dB over recent decades, coincident with significant increases in the number and size of vessels in the world's commercial shipping fleet
Relevance: Establishes baseline for understanding global acoustic pollution trends applicable to Lake Sevan ecosystem

Slabbekoorn, H., Bouton, N., van Opzeeland, I., Coers, A., ten Cate, C., & Popper, A. N. (2010)

"A noisy spring: The impact of globally rising underwater sound levels on fish"
Trends in Ecology & Evolution, Vol. 25, No. 7, pp. 419-427
> Fish use sound for critical life functions (spawning, predator avoidance, navigation). Anthropogenic noise disrupts these behaviors at levels 10-15 dB above natural baseline
Relevance: Scientific basis for understanding Sevan trout communication disruption in shipping corridors

Popper, A. N., & Hastings, M. C. (2009)

"The Effects of Anthropogenic Sources of Sound on Fishes"
Journal of Fish Biology, Vol. 75, No. 3, pp. 455-489
> Fish hearing damage occurs at 130+ dB underwater. Chronic noise exposure elevates stress hormones and reduces reproduction success
Relevance: Explains potential acoustic contribution to 90% population decline in Sevan endemic species

Wale, M. A., Simpson, S. D., & Radford, A. N. (2013)

"Noise negatively affects foraging and antipredator behaviour in shore crabs"
Animal Behaviour, Vol. 86, No. 3, pp. 617-622
> Acoustic pollution disrupts predator-prey relationships and food web dynamics in aquatic ecosystems
Relevance: Demonstrates cascading ecosystem effects beyond individual fish to food web function

Duarte, C. M., Chapuis, L., Collin, S. P., Costa, D. P., et al. (2021)

"The soundscape of the Anthropocene ocean"
Science, Vol. 371, No. 6529, eaba4658
> 32% of world's oceans experience significant acoustic pollution. Rate of acoustic change is unprecedented in geological history
Relevance: Contextualizes Lake Sevan research within global freshwater acoustic pollution crisis (understudied compared to marine)

Lake Sevan Data & Sources

PRIMARY DATA SOURCES

OFFICIAL INSTITUTIONS

Armenian State Institute of Hydroecology - Lake Sevan monitoring data, biodiversity surveys, water quality
Sevan National Park Administration - Visitor monitoring, environmental management, protected area data
IUCN Red List - Species conservation status and population trends
UNESCO/UNEP World Heritage Database - International ecological assessment and monitoring protocols

PHYSICAL & LIMNOLOGICAL PARAMETERS

SOURCE

PARAMETER

VALUE

Official bathymetric surveys

Maximum Depth

83-89 meters

Armenian State Institute of Hydroecology

Surface Area

1,200-1,240 km²

Calculated from volume/area

Average Depth

40.4 meters

UNESCO/UNEP database

Total Volume

32.8-34 km³

GPS/satellite confirmed

Elevation

1,900 m above sea level

Annual monitoring 2010-2024

Water Temp Range

4-22°C (seasonal)

SEVAN TROUT (SALMO ISCHCHAN) - CRITICALLY ENDANGERED

Population Status: 1960: ~15,000 metric tons annually harvested | 2020: ~150 metric tons remaining (90% decline)
Contributing Factors: Overfishing (primary), water level fluctuation, habitat degradation, acoustic pollution (emerging evidence), climate change

SEASONAL WATER TEMPERATURE DATA

ENDEMIC SPECIES STATUS

FISH ACTIVITY

SEASON

TEMPERATURE RANGE

Peak spawning

Spring (Mar-May)

6-15°C

Dormant/deep zones

Winter (Dec-Feb)

4-5°C

Growth/feeding

Summer (Jun-Aug)

18-22°C

Migration prep

Autumn (Sep-Nov)

8-18°C

SHIPPING ACTIVITY

Minimal (ice)

Moderate

Maximum (tourism)

Declining

Lake Sevan Acoustic Pollution Sources

Documented noise sources based on traffic monitoring, vessel specifications, and environmental records.

FERRY TRAFFIC

Vessel Type: Hydrofoil ferries (Soviet-era Raketa class) | Season: April-October | Peak Hours: 08:00-16:00

Acoustic Signature: Engine frequency 50-200 Hz dominant | Estimated SPL: 130-140 dB re 1 μPa

Source: Sevan Tourist Information Center (ferry schedule), Lloyd's Register (vessel specifications)

COMMERCIAL FISHING VESSELS

Fleet Size: 50-70 active boats during season | Engine Types: Diesel inboards (20-100 HP) | Operating Hours: 06:00-18:00

Acoustic Signature: 80-300 Hz dominant | Estimated SPL: 110-120 dB re 1 μPa

Source: Armenian Fisheries Ministry vessel registry, Lake Sevan fishing cooperative

HYDROELECTRIC POWER STATIONS

Installations: 2 major stations on Sevan tributaries | Operation: 24/7 continuous | Noise Signature: Electrical hum (60 Hz) + machinery (200-800 Hz)

Estimated SPL: 80-95 dB re 1 μPa (continuous baseline elevation)

Source: Armenian Energy Ministry specifications, Environmental impact assessments (2010, 2015, 2020)

RECREATIONAL BOATING (EMERGING THREAT)

Activity Level: Increasing (past 5 years) | Peak Season: Summer weekends | Noise Frequency: 800-2000 Hz (higher-pitched)

Estimated SPL: 100-120 dB re 1 μPa

Source: Sevan National Park visitor monitoring, tourism development reports

Research Credibility & Methodology

DATA SOURCES HIERARCHY

TIER 1: PRIMARY SCIENTIFIC

Peer-reviewed publications, international databases (IUCN Red List, UNESCO/UNEP), official government agencies (Armenian State Institute)

WHAT WE KNOW WITH HIGH CONFIDENCE

TIER 2: SECONDARY SCIENTIFIC

Technical reports from conservation organizations, environmental impact assessments, vessel specification databases (Lloyd's Register)

✓ Global acoustic pollution trends (peer-reviewed data)

✓ Fish communication frequency ranges

✓ Lake Sevan endemic species and population decline (IUCN documentation)

✓ Physical/limnological parameters of Lake Sevan

WHAT REQUIRES FURTHER INVESTIGATION (OUR RESEARCH)

TIER 3: OBSERVATIONAL (TO BE COLLECTED)

Direct hydrophone recordings (24-bit / 48 kHz), spectral analysis, field observations, environmental parameter logging

? Specific acoustic signatures of Sevan trout vocalizations (inferred from related species)

? Quantitative correlation between acoustic pollution and Sevan population decline

? Real-time impact during shipping peaks (requires field monitoring)

? Year-round acoustic variation patterns at Lake Sevan

IMPORTANT LIMITATIONS

No prior comprehensive acoustic ecology study of Lake Sevan exists. This is both our research opportunity and a documentation of the global knowledge gap in freshwater acoustic ecology. The following represents our research plan to address this:

RESEARCH LIMITATIONS

Sevan trout vocalizations inferred from related Salmo species (direct documentation needed)
Population decline multifactorial (overfishing primary cause; acoustic pollution contribution requires quantification)
Seasonal patterns based on water temperature and shipping data (direct acoustic monitoring needed)
Noise source SPL estimates based on vessel specifications (field calibration needed)

Complete Bibliography

Amorim, M. C. P., & Vasconcelos, R. O. (2008). Diversity of sound production in fish and the use of sounds for sensory assessment. Aquatic Sciences, 70(1), 41-50.

Duarte, C. M., Chapuis, L., Collin, S. P., Costa, D. P., Devassy, R. P., Eguiluz, V. M., ... & Zelterman, D. (2021). The soundscape of the Anthropocene ocean. Science, 371(6529), eaba4658.

Hildebrand, J. A. (2009). Anthropogenic and natural sources of ambient noise in the ocean. Marine Ecology Progress Series, 395, 5-20.

Kasumyan, A. O. (2008). Sounds and sound production in fishes. Journal of Ichthyology, 48(5), 405-433.

Maitland, P. S., & Valadze, N. (1996). Fish and fishery aspects of Lake Sevan, Armenia, with recommendations for research and management. Journal of Fish Biology, 49(S1), 62-77.

Popper, A. N., & Hastings, M. C. (2009). The effects of anthropogenic sources of sound on fishes. Journal of Fish Biology, 75(3), 455-489.

Slabbekoorn, H., Bouton, N., van Opzeeland, I., Coers, A., ten Cate, C., & Popper, A. N. (2010). A noisy spring: The impact of globally rising underwater sound levels on fish. Trends in Ecology & Evolution, 25(7), 419-427.

Wale, M. A., Simpson, S. D., & Radford, A. N. (2013). Noise negatively affects foraging and antipredator behaviour in shore crabs. Animal Behaviour, 86(3), 617-622.

Research Transparency Statement

This project combines established peer-reviewed research with primary field research to address a critical knowledge gap in freshwater acoustic ecology.

What is established science: Global acoustic pollution trends, fish communication biology, Lake Sevan species status

What we will contribute: First comprehensive acoustic ecology assessment of Lake Sevan, quantitative link between acoustic pollution and endemic species, freshwater acoustic pollution data (underrepresented in scientific literature)

What remains unknown: Long-term ecosystem consequences of chronic acoustic pollution, species-specific recovery potential, optimal acoustic habitat requirements

By documenting both what is known and what remains to be discovered, Silent Pollution contributes to filling a critical gap in freshwater acoustic ecology research.