Barnacles as biological flow indicators.

Area of Science:

• Ecology
• Marine Biology
• Biophysics

Background:

• Hydrodynamic stress is a key factor shaping marine ecosystems.
• Quantifying hydrodynamic forces in situ is challenging due to instrumentation costs and reliability issues.
• Barnacles exhibit phenotypic plasticity in response to environmental conditions.

Purpose of the Study:

• To investigate the potential of barnacles, specifically ivory barnacles (Amphibalanus eburneus), as biological indicators of hydrodynamic flow.
• To determine if morphological changes in barnacle cirri can be used to quantify relative flow differences.

Main Methods:

• Reciprocal transplant experiments of Amphibalanus eburneus between wave-exposed and wave-protected sites.
• Transplantation of barnacles into controlled low (<5 cm/s) and high (>25 cm/s) flow environments, with some individuals shielded to reduce flow.
• Measurement of cirral dimensions to assess morphological plasticity in response to varying flow regimes.

Main Results:

• Amphibalanus eburneus exhibited significant differences in cirral morphology between high and low flow sites.
• Phenotypic changes in barnacle morphology were observed within two weeks and were reversible upon relocation.
• Flow velocity, rather than wave action alone, was identified as the primary driver of barnacle morphological changes.

Conclusions:

• Barnacles serve as effective, low-cost biological indicators for assessing relative differences in hydrodynamic flow.
• The phenotypic plasticity of barnacle cirri provides a valuable tool for ecological studies in wave-swept and estuarine environments.
• This method offers an accessible alternative to traditional instrumentation for flow measurement.