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Landry, MR, Lorenzen CJ.  1989.  Abundance, distribution, and grazing impact of zooplankton on the Washington shelf. Coastal oceanography of Washington and Oregon. ( Landry MR, Hickey BM, Eds.).:175-210., Amsterdam ; New YorkNew York, NY, U.S.A.: Elsevier ;Distributor for U.S. and Canada, Elsevier Science Pub. Abstract
Landry, MR, Kirshtein J, Constantinou J.  1996.  Abundances and distributions of picoplankton populations in the central equatorial Pacific from 12 degrees N to 12 degrees S, 140 degrees W. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 43:871-890.   10.1016/0967-0645(96)00018-5   AbstractWebsite

Abundances and distributions of picoplankton were studied on two cross-equatorial transect cruises (12 degrees N, 140 degrees W-12 degrees S, 135 degrees W) during February-March (TT007) and August-September 1992 (TT011). Samples were collected in the upper 200 m from early-morning and late-afternoon hydrocasts at 15 stations on each cruise (60 depth profiles, 820 samples). Populations of heterotrophic bacteria, Prochlorococcus, Synechococcus and small autotrophic eukaryotes were enumerated by dual-beam how cytometry. At the northern end of the transect (7-12 degrees N), abundances and vertical distributions were similar to those reported for the oligotrophic North Pacific gyre, with Prochlorococcus and heterotrophic bacteria dominating in the upper euphotic zone, and Synechococccus and eukaryotes exhibiting peaks in cell abundance at depth. All populations were abundant throughout the euphotic zone close to the equator and at the southern end of the transect. Heterotrophic bacteria and Synechococcus were generally more abundant in late-afternoon hydrocasts. The diel enhancement followed the temporal pattern in beam c and suspended particulates, and was particularly strong in the equatorial upwelling region where it averaged 13.6% of the morning population for heterotrophic bacteria and 22.3% for Synechococcus. Conservative estimates of daily growth rates from these data are 0.25 and 0.40 day(-1), respectively, for the two populations. Near-surface maxima in heterotrophic bacteria were symmetrical around the equator, centered around 5 degrees S and 5 degrees N. Prochlorococcus was most abundant during local summer conditions at the respective ends of the transect. A minimum occurred in association with a dense aggregation of buoyant diatoms at the convergent front of a tropical instability wave (2 degrees N, TT011). The ratio of Prochlorococcus to total bacteria was generally in the range of 0.15-0.2 for the upper water column, but varied during TT011 from > 0.3 for the most northern stations to <0.1 at the 2 degrees N front. At higher latitudes, Synechococcus was more numerous during El Nino conditions (TT007) on both sides of the equator and at southern stations on both cruises. Autotrophic eukaryotes were more abundant during local winters at the ends of the transect and during the ''cold tongue'' conditions (TT011) at the equator. Picoplankton account for most of the chlorophyll biomass and primary production in the central equatorial Pacific. Nonetheless, their abundances and distributions are relatively stable and conservative while other populations, such as diatoms, respond more dramatically to environmental forcing. Copyright (C) 1996 Elsevier Science Ltd.

Al-Mutairi, H, Landry MR.  2001.  Active export of carbon and nitrogen at Station ALOHA by diel migrant zooplankton. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 48:2083-2103.   10.1016/s0967-0645(00)00174-0   AbstractWebsite

With a high proportion of diel migratory zooplankton and low particle fluxes, the oligotrophic subtropical Pacific is a region where migrant-mediated export of materials across the base of the euphotic zone should be particularly important for elemental budgets. To assess the magnitude of this export flux at Stn. ALOHA (22 degrees 45'N, 158 degreesW), we determined size-structured migrant biomass on 26 cruises (1994-1996) and used allometric equations to compute metabolic losses of respiratory carbon (DIC) and excreted ammonium (DIN) at the migrant's daytime depth (temperature). Depth-integrated (155m) migrant biomass varied interannually from 286 to 457 mg DW m(-2) and seasonally from 285 to 550 mg DW m(-2) (fall versus spring), with an overall average of 394 mg DWm(-2). The 2-5 mm size-fraction always dominated. Migrant fluxes varied from 0.22 to 0.37 mmol DIC m(-2) d(-1) and from 0.033 to 0.055 mmol DIN m(-2) d(-1) between years, with an overall average of 0.304 mmol C and 0.045 mmol N m(-2) d(-1) (15 and 20% of trap PC and PN fluxes). The fluxes were highest in the spring (0.405 mmol C and 0.060 mmol N m(-2) d(-1); 18 and 24% of trap PC and PN). Strong migratory taxa, defined as those that were virtually absent from the euphotic zone during the day, were dominated by Pleuromamma and Euphausia spp. and Aetideid copepods and accounted for 40% of the total biomass-derived estimates. Using mean cruise biomass structures and temperature information from Stn. ALOHA, migrant flux estimates with different literature-derived metabolic relationships and assumptions typically varied within 20% for carbon and 25% for nitrogen. When compared on the same basis, migrant flux estimates as % trap fluxes were higher for oligotrophic regions compared to the high-nutrient, low-chlorophyll equatorial Pacific. Long-term averages of migrant biomass were substantially (two- to three-fold) higher in the subtropical Pacific compared to the Atlantic, but migrant flux estimates were similar due to higher temperatures (18 versus 9 degreesC) at daytime depths in the Atlantic. Including the effects of undersampled micronekton, dissolved organic excretion, mortality losses at depth and inter-zonal fecal transport, mean flux estimates were about doubled for carbon (30% of trap PC) and approximately tripled for nitrogen (57% of trap PN) relative to those for DIC and DIN metabolic losses. (C) 2001 Elsevier Science Ltd. All rights reserved.

Decima, M, Landry MR, Bradley CJ, Fogel ML.  2017.  Alanine delta(15) N trophic fractionation in heterotrophic protists. Limnology and Oceanography. 62:2308-2322.   10.1002/lno.10567   AbstractWebsite

We evaluated differences in the N-15 isotopic enrichment factors of trophic amino acids (AA) for protistan (microzooplankton) and metazoan (mesozooplankton) consumers, testing the hypothesis that delta N-15 of alanine (ala) increases in both consumer types, while glutamic acid (glu) enriches mainly in mesozooplankton. AA delta N-15 values were measured for dinoflagellate and ciliate grazers and their respective algal prey (Oxyrrhis marina/Dunaliella tertiolecta and Favella sp./Heterocapsa triquetra) in four two-stage chemostat experiments, including treatments with different nitrogen : phosphorous nutrient ratios and light/dark recycling conditions. Propagation of AA N-15 enrichment to a metazoan consumer was also assessed in two-and three-stage chemostat experiments simulating simple "classical" (Calanus pacificus and the diatom Thalassiosira weissflogii) and "multivorous" (C. pacificus, O. marina, and D. tertiolecta) food chains. We found small or negligible 15 N-enrichment of glu for both protistan grazers, while ala enrichment was consistently greater and similar to that in metazoan consumers. Ala and glu delta N-15 values were both highly elevated in C. pacificus relative to prey, and enrichment was higher with autotrophic diets. These laboratory results suggest that ala may be used as an alternate, accurate isotopic proxy for quantifying protistan contributions to trophic structure in aquatic systems.

Vedernikov, VI, Bondur VG, Vinogradov ME, Landry MR, Tsidilina MN.  2007.  Anthropogenic influence on the planktonic community in the basin of Mamala Bay (Oahu Island, Hawaii) based on field and satellite data. Oceanology. 47:221-237.   10.1134/s0001437007020099   AbstractWebsite

The anthropogenic impact on the biomass of coastal plankton communities caused by submerged disposal of urban sewage waters (dumping) was studied. The observations were carried out in August-September of 2002-2004 in Mamala Bay (Oahu Island, Hawaii) using satellite and sea truth methods. An analysis of the variability of the integral indicators of the water column determined on the basis of shipborne measurements allowed us to divide them into two groups: the elements most sensitive to the pollution (heterotrophic bacteria (H-Bact), the phototrophic cyanobacteria Synechococcus spp. (SYN), and chlorophyll a (CHLa)) and the elements that manifested episodic positive dependence on the inflow of the polluted waters (heterotrophic unicellular eukaryotes, small unicellular algae, the phototrophic green bacteria Prochlorococcus spp., as well as the total biomass of microplankton). It was shown that the submerged wastewater disposal in the region of the diffuser of the dumping device led to an insignificant (1.2-1.4 times, on the average) local increase in the integral biomass of H-Bact, SYN, and in the content of CHLa. A similar but sharper (1.5-2.1, on the average) increase in these parameters was found in the water layers with maximal biomasses. The possible pathways of disposed waters (under the pycnocline, at its upper boundary, and in the entire mixed layer) were analyzed on the basis of studying the vertical displacement of the biomasses of H-Bact, SYN, and prochlorophytes. The possibility of using the optical anomalies distinguished from satellite data as markers of anthropogenic eutrophication caused by dumping was confirmed. Application of such markers depends on the water transparency and on the shapes of the curves of the vertical distribution of autotrophic organisms.

Ohman, MD, Rudnick DL, Chekalyuk A, Davis RE, Feely RA, Kahru M, Kim HJ, Landry MR, Martz TR, Sabine CL, Send U.  2013.  Autonomous ocean measurements in the California Current ecosystem. Oceanography. 26:18-25. AbstractWebsite

Event-scale phenomena, of limited temporal duration or restricted spatial extent, often play a disproportionately large role in ecological processes occurring in the ocean water column. Nutrient and gas fluxes, upwelling and downwelling, transport of biogeochemically important elements, predator-prey interactions, and other processes may be markedly influenced by such events, which are inadequately resolved from infrequent ship surveys. The advent of autonomous instrumentation, including underwater gliders, profiling floats, surface drifters, enhanced moorings, coastal high-frequency radars, and satellite remote sensing, now provides the capability to resolve such phenomena and assess their role in structuring pelagic ecosystems. These methods are especially valuable when integrated together, and with shipboard calibration measurements and experimental programs.