Variation in benthic long-term data of transitional waters: Is interpretation more than speculation?

Area of Science:

• Marine Ecology
• Environmental Science
• Oceanography

Background:

• Long-term biological data in marine habitats are crucial for detecting anthropogenic impacts and climate-induced shifts.
• Transitional waters present challenges due to complex environmental factors like water mass dynamics, salinity, and oxygen variability, which can obscure ecological signals.
• Interpreting fluctuations in marine populations requires understanding the interplay of multiple abiotic variables.

Purpose of the Study:

• To interpret long-term macrozoobenthic data from the south-western Baltic Sea.
• To relate benthic parameters and indices to environmental fluctuations, including salinity, oxygen, and the North Atlantic Oscillation (NAO) index.
• To investigate the complexity of environmental drivers influencing benthic systems at a local scale.

Main Methods:

• Statistical analysis of 35 years of modelled and measured data from three stations.
• Examination of major macrozoobenthic parameters (abundance, biomass, species numbers).
• Calculation and analysis of derivative macrozoobenthic indices (Shannon diversity, Margalef, Pilou's evenness, Hurlbert).

Main Results:

• Long-term trends in macrozoobenthic abundance, biomass, and species numbers were successfully interpreted.
• Benthic parameters and indices were related to long-term fluctuations in salinity and oxygen levels.
• The North Atlantic Oscillation (NAO) index was incorporated into the analysis.
• Results indicate that the benthic system is influenced by multiple environmental drivers, not a single factor.

Conclusions:

• The benthic system in the south-western Baltic Sea exhibits a complex response to environmental variability.
• No single environmental driver tightly controls the benthic system.
• Spatially varying temporal responses highlight the intricate nature of marine ecosystem dynamics.