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Laws, EA, Landry MR, Barber RT, Campbell L, Dickson ML, Marra J.  2000.  Carbon cycling in primary production bottle incubations: inferences from grazing experiments and photosynthetic studies using (14)C and (18)O in the Arabian Sea. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 47:1339-1352.   10.1016/s0967-0645(99)00146-0   AbstractWebsite

Estimates of photosynthesis based on the incorporation of (14)C-labeled inorganic carbon into particulate carbon were compared to estimates of gross photosynthesis based on net O(2) production and the production of (18)O(2) from H(2)(18)O during the US Joint Global Ocean Flux Study (US JGOFS) Arabian Sea process cruises. For samples incubated below the surface and at optical depths < 3, the (14)C uptake : gross photosynthesis ratio averaged 0.45 +/- 0.1. This result is in accord with theoretical considerations of the combined effects of the Mehler reaction, photorespiration, dark respiration, excretion, and grazing effects on the two estimates of photosynthesis. The (14)C uptake:gross photosynthesis ratio was distinctly higher (0.62) for samples incubated at the surface. This result is likely due to UV light effects, since the O(2) and (14)C incubations were done in quartz and polysulfone bottles, respectively. The (14)C uptake:gross photosynthesis ratio was lower (0.31) for bottles incubated at optical depths > 3. This result probably reflects an increase in the ratio of dark respiration to net photosynthesis in the vicinity of the compensation light level. (C) 2000 Elsevier Science Ltd. All rights reserved.

Stukel, MR, Kelly TB, Aluwihare LI, Barbeau KA, Goericke R, Krause JW, Landry MR, Ohman MD.  2019.  The Carbon:(234)Thorium ratios of sinking particles in the California current ecosystem 1: relationships with plankton ecosystem dynamics. Marine Chemistry. 212:1-15.   10.1016/j.marchem.2019.01.003   AbstractWebsite

We investigated variability in the C:Th-234 ratio of sinking particles and its relationship to changing water column characteristics and plankton ecological dynamics during 29 Lagrangian experiments conducted on six cruises of the California Current Ecosystem Long-Term Ecological Research (CCE-LTER) Program. C:Th-234 ratios of sinking particles collected by a surface-tethered sediment trap ((CThST)-Th-:234) varied from 2.3 to 20.5 mu mol C dpm(-1) over a depth range of 47-150 m. C:Th-234(ST) was significantly greater (by a factor of 1.8) than C:Th-234 ratios of suspended > 51-mu m particles collected in the same water parcels with in situ pumps. C:Th-234 ratios of large (> 200-mu m) sinking particles also exceeded those of smaller sinking particles. C:Th-234(ST) decreased with depth from the base of the euphotic zone through the upper twilight zone. C:Th-234(ST) was positively correlated with several indices of ecosystem productivity including particulate organic carbon (POC) and chlorophyll (Chl) concentrations, mesozooplankton biomass, and the fraction of Chl > 20-mu m. Principal component analysis and multiple linear regression suggested that decaying phytoplankton blooms exhibited higher C:Th-234(ST) than actively growing blooms at similar biomass levels. C:Th-234(ST) was positively correlated with indices of the fractional contribution of fecal pellets in sediment traps when the proportion of fecal pellets was low in the traps, likely because of a correlation between mesozooplankton biomass and other indices of ecosystem productivity. However, when fecal pellets were a more important component of sinking material, C:Th-234(ST) decreased with increasing fecal pellet content. C:Th-234(ST) was also positively correlated with the Si:C ratio of sinking particles. Across the dataset (and across depths) a strong correlation was found between C:Th-234(ST) and the ratio of vertically-integrated POC to vertically-integrated total water column Th-234 (C-v:Th-234(tot)). A mechanistic one-layer, two-box model of thorium sorption and desorption was invoked to explain this correlation. Two empirical models (one using C-v:Th-234(tot); one using depth and vertically-integrated Chl) were developed to predict C:Th-234 ratios in this coastal upwelling biome. The former regression (log(10)(C:Th-234(ST)) = 0.43 x log(10)(C-v:Th-234(tot)) + 0.53) was found to also be a reasonable predictor for C:Th-234(ST) from diverse regions including the Southern Ocean, Sargasso Sea, Subarctic North Pacific, and Eastern Tropical North Pacific.

Greene, CH, Landry MR.  1988.  Carnivorous suspension feeding by the subarctic calanoid copepod Neocalanus cristatus. Canadian Journal of Fisheries and Aquatic Sciences. 45:1069-1074.   10.1139/f88-130   AbstractWebsite

Carnivorous suspension feeding is described for the large subarctic calanoid copepod Neocalanus cristatus. This foraging mode relies on the use of a feeding current to entrain potential prey items and transport them into the copepod's capture area. The extensive use of a feeding current to entrain and transport prey into the capture area distinguishes carnivorous suspension feeding from the predatory modes typically described for other calanoid copepods. The consequences of carnivorous suspension feeding on N. cristatus' prey-selection patterns are significant. Feeding experiments reveal that the vulnerability of naupliar prey declines with increasing prey size, just the opposite result observed for other marine calanoids exhibiting more typical predatory feeding modes. The role of omnivorous feeding by N. cristatus within the pelagic ecosystem of the subarctic Pacific is also discussed. In contrast with earlier hypotheses, the results reported here are consistent with the emerging view that this large suspension-feeding copepod may be having at least as great an impact on the microzooplankton as on the phytoplankton of the region.

Liu, HB, Bidigare RR, Laws E, Landry MR, Campbell L.  1999.  Cell cycle and physiological characteristics of Synechococcus (WH7803) in chemostat culture. Marine Ecology-Progress Series. 189:17-25.   10.3354/meps189017   AbstractWebsite

The marine cyanobacterium Synechococcus spp. is one of the most abundant picoplanktonic photoautotrophs in the world's oceans. When grown in nitrogen-limited chemostat culture under continuous light, Synechococcus strain WH7803 displays a bimodal DNA histogram. Consequently, the duration of each growth phase can be computed from the proportion of cells in each cell cycle phase. We measured cellular DNA distribution, carbon and nitrogen content. and pigment composition of Synechococcus WH7803 in a series of chemostat experiments with growth rate ranging from 0.1 to 0.9 d(-1). Flow cytometric data showed that the duration of each cell cycle phase increased linearly with doubling time, and the fraction of cells in the S and G(2) phases, f(S+G2), was relatively constant at growth rates of less than 1 doubling d(-1). Cellular carbon and nitrogen contents were about 200 and 40 fg cell(-1), respectively, but were much higher for slowly growing cells. The carbon to nitrogen ratio. the carbon to chlorophyll a ratio. and the ratio of zeaxanthin to chlorophyll a all decreased with increasing growth rate. These observed relationships are useful for applying cell cycle analysis to estimate growth rate, or for using cell abundance or pigment concentrations to estimate biomass and productivity of Synechococcus in the sea.

Twining, BS, Baines SB, Fisher NS, Landry MR.  2004.  Cellular iron contents of plankton during the Southern Ocean Iron Experiment (SOFeX). Deep-Sea Research Part I-Oceanographic Research Papers. 51:1827-1850.   10.1016/j.dsr.2004.08.007   AbstractWebsite

Iron (Fe) availability limits phytoplankton biomass and production in large regions of the Southern Ocean and influences community composition and size structure, which may affect C export and other system-level functions. To improve our understanding of Fe partitioning within communities and the response of different components to fertilization, we assessed the cellular Fe contents of individual diatoms, autotrophic flagellates, and heterotrophic flagellates during the recent Southern Ocean Fe Experiment using synchrotron-based X-ray fluorescence (SXRF). Dual Fe-55/C-14 radioisotope incubations were also conducted to estimate Fe:C ratios in size-fractionated plankton. Cellular Fe quotas determined by the two techniques were in close agreement when low amounts of Fe-55 (0.2 nM) were added, but Fe-55 additions of 2 nM resulted in 2-3-fold higher quotas. SXRF assessments of cellular Fe quotas (normalized to C) were generally in good agreement with prior bulk analyses of natural assemblages, but revealed compositional differences among protistan taxa not previously detected. Mean Fe:C ratios for diatoms, autotrophic flagellates, and heterotrophic flagellates from unfertilized waters were 6.0, 8.7, and 14.1 mumol mol C-1, respectively. Smaller cells had higher Fe:C ratios than larger cells. Fertilization enhanced Fe quotas in all cell types, with mean Fe:C ratios increasing approximately 4-fold (from about 10 to about 40 mumol mol C-1) after two Fe additions. This study provides some of the first measurements of Fe quotas in phytoplankton cells from natural communities and the first measurements of Fe quotas in natural protozoa. (C) 2004 Elsevier Ltd. All rights reserved.

Scheinberg, RD, Landry MR.  2005.  Clearance rates and efficiencies of Oikopleura fusiformis on the natural prey assemblage of a subtropical coastal ecosystem. Response of marine ecosystems to global change: ecological impact of appendicularians. ( Gorsky G, Youngbluth MJ, Deibel D, Eds.).:214-230., Paris: Contemporary Publishing International Abstract
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Landry, MR, Beckley LE, Muhling BA.  2019.  Climate sensitivities and uncertainties in food-web pathways supporting larval bluefin tuna in subtropical oligotrophic oceans. Ices Journal of Marine Science. 76:359-369.   10.1093/icesjms/fsy184   AbstractWebsite

Compared with high-latitude seas, the ecological implications of climate change for top consumers in subtropical regions are poorly understood. One critical area of knowledge deficiency is the nature of food-web connections to larvae during their vulnerable time in the plankton. Bluefin tuna (BFT) are highly migratory temperate species whose early life stages are spent in ultra-oligotrophic subtropical waters. Dietary studies of BFT larvae provide evidence of prey-limited growth coupled with strong selection for specific prey typescladocerans and poecilostomatoid copepodswhose paradoxical or poorly resolved trophic characteristics do not fit the conventional understanding of open-ocean food-web structure and flows. Current knowledge consequently leaves many uncertainties in climate change effects, including the possibility that increased nitrogen fixation by Trichodesmium spp. might enhance resiliency of BFT larvae, despite a projected overall decline in system productivity. To advance understanding and future predictions, the complementary perspectives of oceanographers and fisheries researchers need to come together in studies that focus on the trophic pathways most relevant to fish larvae, the factors that drive variability in spawning regions, and their effects on larval feeding, growth, and survival.

Macias, D, Landry MR, Gershunov A, Miller AJ, Franks PJS.  2012.  Climatic control of upwelling variability along the western North American coast. Plos One. 7   10.1371/journal.pone.0030436   AbstractWebsite

The high biological production of the California Current System (CCS) results from the seasonal development of equatorward alongshore winds that drive coastal upwelling. While several climatic fluctuation patterns influence the dynamics and biological productivity of the CCS, including the El Nino-Southern Oscillation (ENSO), the Pacific Decadal Oscillation index (PDO) and the North Pacific Gyre Oscillation (NPGO), the mechanisms of interaction between climatic oscillations and the CCS upwelling dynamics have remained obscure. Here, we use Singular Spectral Analysis (SSA) to reveal, for the first time, low-frequency concordance between the time series of climatic indices and upwelling intensity along the coast of western North America. Based on energy distributions in annual, semiannual and low-frequency signals, we can divide the coast into three distinct regions. While the annual upwelling signal dominates the energy spectrum elsewhere, low-frequency variability is maximal in the regions south of 33 degrees N. Non-structured variability associated with storms and turbulent mixing is enhanced at northerly locations. We found that the low-frequency signal is significantly correlated with different climatic indices such as PDO, NPGO and ENSO with the correlation patterns being latitude-dependent. We also analyzed the correlations between this upwelling variability and sea surface temperature (SST) and sea level pressure (SLP) throughout the North Pacific to visualize and interpret the large-scale teleconnection dynamics in the atmosphere that drive the low-frequency coastal winds. These results provide new insights into the underlying mechanisms connecting climatic patterns with upwelling dynamics, which could enhance our prediction and forecast capabilities of the effects of future oceanographic and climatic variability in the CCS.

Chen, BZ, Liu HB, Landry MR, Dai MH, Huang BQ, Sun J.  2009.  Close coupling between phytoplankton growth and microzooplankton grazing in the western South China Sea. Limnology and Oceanography. 54:1084-1097.   10.4319/lo.2009.54.4.1084   AbstractWebsite

We conducted 28 dilution experiments during August-September 2007 to investigate the coupling of growth and microzooplankton grazing rates among ultraphytoplankton populations and the phytoplankton community and their responses to habitat variability (open-ocean oligotrophy, eddy-induced upwelling, and the Mekong River plume) in the western South China Sea. At the community level, standing stocks, growth, and grazing rates were strongly and positively correlated, and were related to the higher abundance of larger phytoplankton cells (diatoms) at stations with elevated chlorophyll concentration. Phytoplankton growth rates were highest (> 2 d(-1)) within an eastward offshore jet at 13 degrees N and at a station influenced by the river plume. Among ultraphytoplankton populations, Prochlorococcus dominated the more oceanic and oligotrophic stations characterized by generally lower biomass and phytoplankton community growth, whereas Synechococcus became more important in mesotrophic areas (eddies, offshore jet, and river plume). The shift to Synechococcus dominance reflected, in part, its higher growth rates (0.87 +/- 0.45 d(-1)) compared to Prochlorococcus (0.65 +/- 0.29 d(-1)) or picophytoeukaryotes (0.54 +/- 0.50 d(-1)). However, close coupling of microbial mortality rates via common predators is seen to play a major role in driving the dominance transition as a replacement of Prochlorococcus, rather than an overprinting of its steady-state standing stock.

Brzezinski, MA, Baines SB, Balch WM, Beucher CP, Chai F, Dugdale RC, Krause JW, Landry MR, Marchi A, Measures CI, Nelson DM, Parker AE, Poulton AJ, Selph KE, Strutton PG, Taylor AG, Twining BS.  2011.  Co-limitation of diatoms by iron and silicic acid in the equatorial Pacific. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 58:493-511.   10.1016/j.dsr2.2010.08.005   AbstractWebsite

The relative roles of silicon (Si) and iron (Fe) as limiting nutrients in the eastern equatorial Pacific (EEP) were examined in a series of nine microcosm experiments conducted over two years between 110 degrees W and 140 degrees W longitude. Si and Fe additions had consistently different but synergistic effects on macronutrient use, phytoplankton biomass and phytoplankton community structure. Silicon addition increased silicic acid use and biogenic silica production, but had no significant effect on the use of inorganic nitrogen or orthophosphate, chlorophyll accumulation, particulate inorganic (PIC) carbon accumulation, or plankton community composition relative to controls. That result, together with observations that Si addition increased the cellular Si content of the numerically dominant diatom by similar to 50%, indicates that the main effect of Si was to regulate diatom silicification. Like the effect of Si, Fe addition increased the rate of silicic acid use and biogenic silica production and had no effect on PIC production. Unlike the effect of Si, Fe addition also enhanced rates of organic matter production, had no effect on cellular Si content of diatoms, and resulted in the growth of initially rare, large (> 40 mu m) diatoms relative to controls, indicating that Fe limitation acts mainly through its effects on growth rate and phytoplankton community composition. A pennate diatom of the genus Pseudo-nitzschia dominated the diatom assemblage in situ, grew readily in the controls and did not show a strong growth response to either Fe or Si addition suggesting that its growth was regulated by other factors such as grazing or light. Addition of germanium, an inhibitor of diatom cell division, eliminated the effects of Fe on macronutrient use, biogenic silica production and chlorophyll accumulation and phytoplankton community composition, consistent with a predominantly diatom response to Fe addition. The lack of a response of PIC production to Fe suggests that coccolithophores were not Fe limited. Addition of Fe and Si together resulted in the greatest levels of nutrient drawdown and biomass accumulation through the effect of Fe in promoting the growth of large diatoms. The results suggest a form of co-limitation with Si regulating diatom silicification and the rate of biogenic silica production while Fe regulates the production of organic matter through limitation of phytoplankton growth rates, in particular those of large diatoms. The results argue against Si regulation of new production in the EEP under average upwelling conditions. Iron addition was necessary and sufficient to stimulate complete removal of nitrate within the equatorial upwelling zone suggesting that new production was restricted by low ambient dissolved Fe consistent with results from in situ Fe fertilization experiments conducted to the south of the equator outside of the equatorial upwelling zone. (C) 2010 Elsevier Ltd. All rights reserved.

Herman, AJ, Landry MR, Hickey BM, Winter DF.  1989.  Coastal upwelling dynamics. Coastal oceanography of Washington and Oregon. ( Landry MR, Hickey BM, Eds.).:211-254., Amsterdam ; New YorkNew York, NY, U.S.A.: Elsevier ;Distributors for the U.S. and Canada, Elsevier Science Pub. Co., Abstract

The Washington-Oregon coastal zone is a classical Eastern Boundary Current region. The area is extremely productive, the productivity dependent on near-shore infusions of nutrients into surface layers during wind-driven coastal upwelling. The Washington-Oregon coastline is much more regular than areas off California or off the East Coast, where large capes lend complexity to both the physical environment and the ecosystem response. The relatively straight coastline and broad, deep shelf greatly simplify the physical environment, so that processes responsible for much of the variance are more easily identified. The system response from mid-Oregon northward, although not strictly two-dimensional, is more so than many other coastal areas. Consequently, the system is amenable to the testing of relatively simple models integrating wind forcing with physical, chemical and biological responses in the upper water column. This book is an integrated synthesis of physical, chemical, geological and biological research in a dynamic shelf ecosystem characterized by seasonal, wind-driven upwelling, major river influences, extensive silt deposits, productive pelagic and demersal fisheries, and unique surf-zone communities. The broad scope of the book includes: detailed analyses of physical circulation and sediment transport; production and utilization of organic matter in the marine food web; river influences on regional hydrology and sediment deposition; inputs and inventories of anthropogenic chemicals in the water column and sedimentary deposits. Much of the book is based on primary analyses of previously unpublished data sets. Interdisciplinary approaches are emphasized in models and discussions of coastal upwelling dynamics, hydrographic patterns and anomalies, benthic boundary-layer processes and larval transport, oceanographic influences on commercial stocks, mechanics of chemical cycling and accumulation, and surf-zone production. An extensive index and references complete the book. The book is intended both to document and explain specific regional features of the Washington/Oregon shelf system and, more generally, to illustrate the complexities of interactive influences on the dynamics of coastal ecosystems. Oceanographers, both researchers and students, will be very interested in this book, and it can also be used by governmental agencies and industries dealing with coastal zone management and planning.

Kenitz, KM, Visser AW, Ohman MD, Landry MR, Andersen KH.  2019.  Community trait distribution across environmental gradients. Ecosystems. 22:968-980.   10.1007/s10021-018-0314-5   AbstractWebsite

Variability in community composition is often attributed to underlying differences in physical environments. However, predator-prey interactions can play an equally important role in structuring communities. Although environmental differences select for different species assemblages, less is known about their impacts on trait compositions. We develop a trait-based analysis of plankton communities of the southern California Current System across multiple trophic levels, from bacteria to mesozooplankton, and over a gradient of environmental conditions, from the oligotrophic open ocean to coastal upwelling. Across a factor of four differences in total community biomass, we observe similarities in the size structure along the environmental gradient, with the most pronounced departures from proportional variations in the biomasses found in the largest protists (> 40 mu m). Differences in the trait distributions emerge within a small range of size groups: greater biomass contribution of larger autotrophs (> 10 mu m) is observed only for the upwelling region.

Stukel, MR, Landry MR.  2010.  Contribution of picophytoplankton to carbon export in the equatorial Pacific: A reassessment of food web flux inferences from inverse models. Limnology and Oceanography. 55:2669-2685.   10.4319/lo.2010.55.6.2669   AbstractWebsite

The paradigm that carbon export is derived almost exclusively from the primary production of large phytoplankton has been challenged by inverse ecosystem modeling studies that suggest that most carbon export in the open ocean is fueled by picophytoplankton. To readdress this hypothesis, we use an inverse model to synthesize the planktonic rate measurements from a pair of recent cruises in the equatorial Pacific. The analysis based on this new experimental data, which crucially include vertically integrated taxon-specific production and grazing estimates, largely resolve the unexpected results of the previous inverse studies, including unbalanced growth and grazing processes and the dominance of production by picophytoplankton. While this very small size class does not produce the majority of phytoplankton carbon that is eventually exported to depth (only 23%, vs. 73% from a previous analysis of Joint Global Ocean Flux Study Equatorial Pacific data), our base model supports the conclusion that the role of picophytoplankton in vertical carbon flux is largely proportional to their contribution to net primary productivity (though neither is proportional to biomass). We show, however, that export-production proportionality is sensitive to the model representation of the detrital pool such that the relative export role of picophytoplankton declines substantially for an alternate model with size-structured detritus. A definitive assessment of the role of picoplankton in vertical carbon flux will thus require detailed experimental examination of the origin, composition, and fate of euphotic zone detrital material.

Stukel, MR, Ohman MD, Benitez-Nelson CR, Landry MR.  2013.  Contributions of mesozooplankton to vertical carbon export in a coastal upwelling system. Marine Ecology Progress Series. 491:47-+.   10.3354/meps10453   AbstractWebsite
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Landry, MR, Lehner-Fournier JM.  1987.  Control of diatom blooms in the Subarctic Pacific: experimental studies in microcosms. International Symposium on Marine Ecosystem Enclosure Experiments. ( Wong CS, Harrison PJ, Eds.)., Beijing: International Development Research Centre Abstract

This symposium on marine ecosystem enclosed experiments (MEEE) consists of nine review papers that describe various types of ecosystem enclosures and a series of papers resulting from enclosure experiments in Xiamen, People's Republic of China, and Saanich Inlet, BC, Canada. The reviews on types of enclosures include benthic enclosures for rocky and sandy shores and the effects of pollutants (primarily hydrocarbons) on bacteria, macroalgae, and invertebrates. The pelagic enclosures were used to study the control of phytoplankton blooms, the uptake and release of dissolved organic substances, and the effects of pesticides on freshwater ecosystems. Six enclosure experiments were conducted in China and Canada from 1986-87. Some of these experiments examined the effects of contaminated sediments, primarily heavy metals, on bacteria, phytoplankton, and zooplankton and the pathways and fates of these heavy metals in the seawater. Other experiments studied the chemistry and biological effects of chemically dispersed oil.

Calbet, A, Landry MR, Scheinberg RD.  2000.  Copepod grazing in a subtropical bay: species-specific responses to a midsummer increase in nanoplankton standing stock. Marine Ecology Progress Series. 193:75-84.   10.3354/meps193075   AbstractWebsite

Ingestion rates of 4 small copepod species (Oithona simplex, O, nana, Acrocalanus inermis and Parvocalanus crassirostris) were investigated in Kaneohe Bay, Hawaii, during a midsummer increase of the pico- and nanoplankton communities. There was no evidence that adult female copepods fed significantly on picoplankton-sized cells. However, all the species responded behaviorally to variations in the concentration (10 to 110 mu g C l(-1)) and size spectrum (relative increase of cells >5 mu m) of nanoplankton prey. The copepods generally behaved as opportunistic particle feeders, demonstrating higher consumption rates on the most abundant cells (2-5 mu m nanoplankton); however, autotrophs were usually selected over heterotrophs of similar size. Maximum ingestion rates were similar for the 2 calanoids and O, nana (around 120000 cells copepod(-1) d(-1)) and lower for O, simplex (around 40000 cells copepod(-1) d(-1)), but biomass-specific rates of O. simplex equaled those of the other species. At the highest nanoplankton concentrations, the ingestion rates of copepods appeared saturated, daily rations ranging from 100 % body C d(-1) for A. inermis to 260 % body C d(-1) for P. crassirostris. The differences between ingestion rates measured as cells per copepod per day and those converted to carbon suggested that ingestion might be held below potential by the cumulative handling times of individual prey rather than the physiological constraints of food consumption and digestive processing.

Piontkovski, SA, Landry MR.  2003.  Copepod species diversity and climate variability in the tropical Atlantic Ocean. Fisheries Oceanography. 12:352-359.   10.1046/j.1365-2419.2003.00250.x   AbstractWebsite

A database synthesized from 19 oceanographic expeditions conducted by the former Soviet Union was used to analyse interannual patterns in copepod species diversity in the tropical Atlantic. Mesozooplankton was collected predominately in vertical hauls through the upper 100 m with Juday nets. The samples from 744 oceanographic stations were identified and enumerated to the species level. To assess species diversity, the Shannon diversity index was used. On the interdecadal scale, no statistically confirmed trend was found in species diversity change over the years sampled ( 1963 - 89). Multiple regression analysis indicated that interannual fluctuations of the South Atlantic High ( pressure and latitude), the Azores High longitude and El Nino-Southern Oscillation (ENSO) index could explain 87% of species diversity fluctuations. Possible mechanisms that drive interannual fluctuations of species diversity are discussed.

Zhang, SW, Chan KYK, Shen Z, Cheung SY, Landry MR, Liu HB.  2017.  A cryptic marine ciliate feeds on progametes of Noctiluca scintillans. Protist. 168:1-11.   10.1016/j.protis.2016.08.005   AbstractWebsite

The dinoflagellate Noctiluca scintillans (Noctiluca) has the ability to reproduce sexually, which may help to increase or restore its population size during periods of blooms or environmental stress. Here, we documented for the first time a marine ciliate Strombidium sp. that feeds on Noctiluca's progametes undergoing stages 5 to 9 of nuclear division. This ciliate frequently swam on or around gametogenic and some vegetative Noctiluca cells. The ciliates associated with gametogenic cells had significantly lower swimming speed and changed direction more frequently than those associated with vegetative cells, which overall increased their time spent around the food patches (progametes). This trophic interaction constitutes an upside-down predator -prey link, in which ciliates within the typical size range of Noctiluca prey, become the predators. Based on the phylogenetic tree (maximum-likelihood), there are 14 environmental clones similar to Strombidium sp. found in other coastal waters, where Noctiluca presence or blooms have been reported. This novel predator-prey relationship could therefore be common in other Noctiluca habitats. Additional studies are needed to assess the magnitude of its impacts on Noctiluca population dynamics and plankton bloom succession. (C)2016 Elsevier GmbH. All rights reserved.