Marine & Aquatic Biology Calculators

Marine & aquatic biology calculators simplify computations for students, researchers, and lab technicians. Quickly estimate salinity, osmotic pressure, chlorophyll-a concentration, plankton biomass, and water stratification indices for research and monitoring.

These tools also include turbidity from Secchi depth, benthic coverage %, dissolved inorganic carbon, fish CPUE, and larval dispersal distance. Use them to optimize experimental design, field studies, and aquatic ecosystem analysis.

⚠ Disclaimer: These calculators use simplified formulas and empirical approximations. They are intended for educational and research purposes only and should not replace professional field measurements or laboratory analyses.

Salinity ↔ Conductivity

Conductivity (mS/cm)

Approx: Salinity (PSU) ≈ 0.65 × Conductivity (mS/cm)

Osmotic Pressure (seawater)

Salinity (g/L NaCl eq.) Temperature (°C)

π ≈ iCRT; assumes NaCl, i=2

Chlorophyll-a (absorbance)

Absorbance at 665 nm Pathlength (cm)

Conc ≈ (Abs × 11.9) / pathlength (µg/L)

Plankton Biomass

Cell count (cells/mL) Biovolume per cell (pg C/cell)

Biomass = count × biovolume (µg C/L)

Water Stratification Index

Surface density (kg/m³) Bottom density (kg/m³) Depth (m)

Index ≈ (ρ_bottom − ρ_surface)/depth

Secchi Depth → Turbidity

Secchi depth (m)

Turbidity ≈ 1.7 / depth (NTU approx.)

Benthic Area Coverage

Area covered (m²) Total area (m²)

Coverage = area covered / total × 100%

Dissolved Inorganic Carbon (approx.)

pH Alkalinity (meq/L)

Approx DIC ≈ Alk × 22 / (pH−6)

Fish CPUE

Fish caught Effort (net-hours)

CPUE = catch / effort

Larval Dispersal Distance

Current velocity (m/s) Duration (days)

Distance ≈ velocity × duration × 86400