PLANKTON ENERGETICS OF RARITAN BAY

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Abstract
Plankton production in Raritan Bay is described based on total chlorophyll data and two series of 24‐hr dark and light bottle differential oxygen experiments. Maximum chlorophyll (γ) recorded was 663 µg L‒1 in a bloom of Massartia rotundata. Utility of pigment data in estimating productivity or biomass is regarded as dubious: i) 17.3 × 106 chains of Skeletonema costatum once corresponded to only trace quantities of chlorophyll; ii) production occurred several times in absence of detectable chlorophyll.In the first (1957) series of experiments, gross production (π) at 1 ft ranged from 4.8 to 531.6 µg O2 L‒1 hr‒1. Ratios of πγ‒1 (when γ > 0) varied from ‒0.4 to 14.1 µg O2 L‒1 hr‒1 µg‒1. Respiration (ρρ) at 1 ft ranged from ‒49.1 to 230.8 µg O2 L‒1 hr‒1, and net production (π ‒ ρ) from ‒24.7 to 483.0.In the second (1959) series at a station 15 ft deep, chlorophyll in the whole water column varied from 14.68 to 173.14 µg cm ‒2 (mean 50.75). The range of π was 1.65– 13.90, of ρ 1.42–24.51, and of (π ‒ ρ) ‒14.63 to 4.53 cal cm‒2 day‒1. Compensation depths ranged from 0 to 6.3 ft (mean 3.0); compensation points varied from 37.1 to 315.7 cal cm‒2 day‒1 (mean 169.3). A model is developed which demonstrates that compensation is the critical variable in water mass metabolism, and that determination of this variable is the main reason for experimentation. Gross production per unit light intensity (I) at a given depth z, (πI‒1)z, ranged 0.3–828.6 µg O2 L‒1 cal‒1 cm‒2. Chlorophyll activity, (πI‒1 γ‒1)z, varied from 0.03 to 6.62 µg O2 L‒1 cal‒1 cm‒2 µg‒1. Total production in the water column relative to incident radiation, πo → z Io‒1, ranged from 0.17 to 1.78% (mean 0.88%). Production efficiency relative to amount of light in the water column, (πI‒1) o→z, was 0.96–28.71 cal kcal‒1 (mean 9.07 or 0.907%). Thermodynamic cost of energy procurement varied from 0.54 to 2.58 cal cal‒1 (mean 1.48), indicating a net energy loss during the study. It is concluded that even if this indicated dystrophy is widespread in the upper estuary, sufficient energy is probably introduced from Lower Bay in the form of standing planktonic biomass to bring the system into positive energy balance.