Regulation of primary productivity rate in the equatorial Pacific

Journal Article · Sun Dec 01 04:00:00 EST 1991 · Limnology and Oceanography; (United States)

DOI:https://doi.org/10.4319/lo.1991.36.8.1803· OSTI ID:6994271

Barber, R T ^[1]; Chavez, F P ^[2]

---

1. Duke Univ. Marine Lab., Beaufort, NC (United States)
2. Monterey Bay Aquarium Research Inst., Pacific Grove, CA (United States)

Analysis of the Chl-specific rate of primary productivity (P{sup B}) as a function of subsurface nutrient concentration at >300 equatorial stations provides an answer to the question: What processes regulate primary productivity rate in the high-nutrient, low-chlorophyll waters of the equatorial Pacific In the western Pacific where there is a gradient in 60-m (NO{sub 3}) from 0 to {approximately}12 {mu}M, the productivity rate is a linear function of nutrient concentration; in the eastern Pacific where the gradient is from 12 to 28 {mu}M, the productivity rate is independent of nutrient concentration and limited to {approximately}36 mg C(mg Chl){sup {minus}1} d{sup {minus}1}, or a mean euphotic zone C-specific growth rate ({mu}) of 0.47 d{sup {minus}1}. However, rates downstream of the Galapagos Islands are not limited; they are 46.4 mg C(mg Chl){sup {minus}1} d{sup {minus}1} and {mu} = 0.57 d{sup {minus}1}, very close to the predicted nutrient-regulated rates in the absence of other limitation. This pattern of rate regulation can be accounted for by a combination of eolian Fe, subsurface nutrients, and sedimentary Fe derived from the Galapagos platform. In the low-nutrient western Pacific the eolian supply of Fe is adequate to allow productivity rate to be set by subsurface nutrient concentration. In the nutrient-rich easter equatorial region eolian Fe is inadequate to support productivity rates proportional to the higher nutrient concentrations, so in this region eolian Fe is rate limiting. Around the Galapagos Islands productivity rates reach levels consistent with nutrient concentrations; sedimentary Fe from the Galapagos platform seems adequate to support increased nutrient-regulated productivity rates in this region.

• OSTI ID: 6994271
• Journal Information: Limnology and Oceanography; (United States), Journal Name: Limnology and Oceanography; (United States) Vol. 36:8; ISSN LIOCA; ISSN 0024-3590
• Country of Publication: United States
• Language: English

Related Subjects

29 ENERGY PLANNING, POLICY, AND ECONOMY
290301 -- Energy Planning & Policy-- Environment
Health
& Safety-- Regional & Global Environmental Aspects-- (1992-)
54 ENVIRONMENTAL SCIENCES
540320* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
560300 -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AQUATIC ORGANISMS
BIOGEOCHEMISTRY
BIOLOGICAL AVAILABILITY
CARBOXYLIC ACIDS
CHEMISTRY
CHLOROPHYLL
ECOLOGICAL CONCENTRATION
ELEMENTS
GEOCHEMISTRY
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
IRON
METALS
NITRATES
NITROGEN COMPOUNDS
NUTRIENTS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PACIFIC OCEAN
PHYTOCHROMES
PHYTOPLANKTON
PIGMENTS
PLANKTON
PLANTS
PORPHYRINS
PRODUCTIVITY
PROTEINS
SEAS
SURFACE WATERS
TRANSITION ELEMENTS