Shallow Water Column Research Articles

Fluctuations in export productivity over the last century from sediments of a southern Chilean fjord (44°S)

Here we present the first reconstruction of changes in surface primary production during the last century from the Puyuhuapi fjord in southern Chile, using a variety of parameters (diatoms, biogenic silica, total organic carbon, chlorins, and proteins) as productivity proxies. Two sediment cores from the head and the center of the fjord were analyzed and compared to gain insights on past changes in productivity in these two different depositional environments. Higher sedimentation rates found at the head of the fjord result from the combination of a shallower water column and a restricted circulation by the occurrence of a sill. Additionally, sediment mixing depths estimated from 210Pb data suggest that suboxic conditions may dominate the bottom water and the sediment–water interface in this location. Productivity of the Puyuhuapi fjord during the last century was characterized by a constant increase from the late 19th century to the early 1980s, then decreased until the late 1990s, and then rose again to present-day values. The influence of rainfall on productivity was most noticeable during periods of low rainfall, which coincided with decreased overall productivity within the Puyuhuapi fjord. Simultaneous variations in productivity and rainfall in the study area suggest that marine productivity could respond to atmospheric–oceanic interactions at a local scale. At a regional scale, marine productivity of the area may be related to other large-scale processes such as the El Niño Southern Oscillation.

Diving ability of Anopheles gambiae (Diptera: Culicidae) larvae.

Anopheles gambiae Giles larvae usually live near the surface of shallow and temporary aquatic habitats. How deep the larvae can dive and how long they can submerge may be related to feeding efficiency and predator avoidance. This study examined diving behavior of An. gambiae larvae in the laboratory. We recorded diving depths and larval mortality of second and fourth instars in clean water and muddy water by using deep water (32-cm) and shallow water (20-cm) columns. In deep water columns with clean water, we found that 2% of second instars and 6% of fourth instars died from diving, whereas 3% of second instars and 11% of fourth instars died in muddy water. The fourth instars dived deeper in muddy water than in clean water. The mortality rates of the fourth instars subjected to diving stimulations were significantly higher than those in the shallow water columns. Therefore, larval diving behavior may offer the benefits of predator avoidance and food acquisition but also incur energetic costs and increased mortality.

Novel decomposition products of chlorophyll- a in continental shelf (Louisiana shelf) sediments: formation and transformation of carotenol chlorin esters

In April 2000, we collected box cores from five stations along a cross-shelf transect on the Louisiana (LA) continental shelf. Novel esters of carotenols and chlorins (carotenoid chlorin esters, CCEs), which are highly specific grazing markers, were identified in surface and deep sediments (>10 cm) from the LA shelf. Chlorophyll- a inventory indicated that CCEs are one of the major decay products of chlorophyll- a in shelf sediments. Abundances of total CCEs (9–18%) in surface sediments along the cross-shelf transect were comparable to the abundance of pheophytin- a, pyropheophytin- a, and total steryl chlorin esters (SCEs). Prior work has identified four CCEs which have dehydrated fucoxanthin/fucoxanthinol as a substitute alcohol of phytol. We report on four newly identified CCEs associated with nondehydrated fuxocanthin/fucoxanthinol esterified to (pyro)pheophorbide- a. These nondehydrated CCEs were generally present in lower concentrations than their dehydrated counterparts, but were detectable by atmospheric pressure chemical ionization (APCI) mass spectrometry coupled with high-performance liquid chromatography (HPLC). We attributed differences between this study and previous work to the time allowed for predepositional decay and grazing processes to occur. The rapid sedimentation of CCEs in the shallow water column (ca. 10 m) on the LA shelf allowed for effective burial of all CCEs compared to the deeper water column regions sampled by previous work. This speculation is supported by the fact that the concentrations of CCEs with nondehydrated fucoxanthin/fucoxanthinol were extremely low in sediments from the site on the outer LA shelf with a deeper (253 m) water column. We also tentatively identified an additional CCE and its isomer as fucoxanthinol didehydrate pyropheophorbide- a ester. We suggest that the formation and transformation of CCEs are primarily controlled by the following three biologically mediated reactions: demethoxycarbonylation, dehydration, and deacetylation. Our laboratory copepod grazing experiment also confirmed that CCEs can be excellent class-specific biomarkers of zooplankton grazing on phytoplankton.

The abundance, vertical flux, and still-water and apparent sinking rates of marine snow in a shallow coastal water column

In Cape Lookout Bight, NC, measurements were made of marine snow (e.g., aggregates >0.5 mm in diameter) abundance and size, the vertical flux of material through the water column, the vertical flux of marine snow, and the measured still-water sinking rate of marine snow. The abundance and size of marine snow was determined from photographs taken by SCUBA divers. Sampled marine snow were used to determine aggregate dry weight. Marine snow flux and measured still-water sinking rate were made using a time-lapse camera that photographed a sediment trap mounted on a drogue. Flow over the drogue mounted sediment trap was <3 cm s −1. Knowing the flux of marine snow into the trap and the abundance of marine snow in the water column, the sinking rate of marine snow sinking freely in the water column (apparent marine snow sinking rate) was calculated. Throughout the study, marine snow was always present and usually abundant (average 125 l −1). The water-column particulate matter load ranged from 8 to 18 mg l −1. The vertical flux of particulate matter through the water column was large (average 74 g m −2 day −1). The average vertical flux was roughly equal to the sedimentation rate estimated from geochronology studies of sediment deposition in Cape Lookout Bight. More than 90% of the variation in the vertical flux of particulate matter through the water column was due to variations in the flux of marine snow. Variations in the vertical flux of marine snow were, however, not significantly correlated to the abundance of marine snow. Measured sinking rates ranged from around 10 to about 150 m day −1, increased with aggregate size, and varied little between days. The calculated apparent sinking rates of marine snow varied a great deal between days and were not similar to the measured sinking rates. The distribution and orientation of marine snow in the water column photographs appeared to delineate small (mm to cm diameter) eddies. Eddies in a random selection of water column photographs were measured. The upper limit to aggregate size appeared to have been set by the size of small turbulent eddies in the water column. The apparent sinking rate of marine snow, the total vertical flux and the flux of marine snow were all significantly correlated ( r>0.97) to the ratio of aggregate dry weight and eddy diameter. The data suggest that marine snow sinking rates were modified by turbulence in the water column.

Algal games: The vertical distribution of phytoplankton in poorly mixed water columns

Phytoplankton often face the dilemma of living in contrasting gradients of two essential resources: light that is supplied from above and nutrients that are often supplied from below. In poorly mixed water columns, algae can be heterogeneously distributed, with thin layers of biomass found on the surface, at depth, or on the sediment surface. Here, we show that these patterns can result from intraspecific competition for light and nutrients. First, we present numerical solutions of a reaction‐diffusion‐taxis model of phytoplankton, nutrients, and light. We argue that motile phytoplankton can form a thin layer under poorly mixed conditions. We then analyze a related game theoretical model that treats the depth of a thin layer of phytoplankton as the strategy. The evolutionarily stable strategy is the depth at which the phytoplankton are equally limited by both resources, as long as the layer is restricted to the water column. The layer becomes shallower with an increase in the nutrient supply and deeper with an increase in the light supply. For low nutrient levels, low background attenuation, and shallow water columns a benthic layer occurs; for intermediate nutrient levels in deep water columns, a deep chlorophyll maximum occurs; and for high nutrient levels, a surface scum occurs. These general patterns are in agreement with field observations. Thus, this model can explain many patterns of algal distribution found in poorly mixed aquatic ecosystems.

Coastal Oceanography Using a Small AUV

Bathymetry, current, temperature, and depth (CTD) measurements using a small, mobile, autonomous underwater vehicle (AUV) platform are described. Autonomous surveys of a shallow water column off the east coast of Florida during December 1997 were carried out using a 2.13-m long, 0.53-m maximum diameter Ocean Explorer series AUV, equipped with a 1200-kHz acoustic Doppler current profiler (ADCP) and a CDT package. At a speed of 1‐2 m s21, this AUV can perform preprogrammed missions over a period of several hours, collecting in situ oceanographic data and storing it on an onboard datalogger. The vehicle may also carry sidescan sonar or a custom small-scale turbulence measurement package or other instruments for subsidiary measurements. The versatility of the AUV allows measurement of oceanographic data over a substantial region, the motion of the platform being largely decoupled from that of any surface mother ship. In the missions of 5 and 11 December 1997, ‘‘lawn mower pattern’’ AUV surveys were conducted over 1 km2 regions on the east coast of Florida, north of Fort Lauderdale, at depths of 7 and 3 m, respectively, in a water column where the depth ranged from 10 to 32 m. During 5 December, the region was subjected to a cold front from the northwest. Local wind measurements show presence of up to 10 m s21 winds at temperatures of up to 108‐158C below normal for the time of the year. The fixed ADCP indicates occurrence of significant internal wave activity in the region. The data collected using the mobile AUV are utilized to develop a map of the bottom topography and examine current, temperature, and density variations in the context of the background information from a fixed bottom‐mounted ADCP and Coastal-Marine Automated Network buoys. The work described here is a significant step in the development of an autonomous oceanographic sampling network, illustrating the versatility of an AUV platform. The data collected during the missions described will form part of a bank for information on the impact of a cold front on shallow subtropical waters. The authors expect to repeat the missions during other such fronts.

Source localization in a shallow water random environment

Source localization in a random ocean environment has been investigated through analysis of data from the SWARM 95 experiment. Both broadband matched-field processing and matched-mode processing have been used for localization. In particular, acoustic data collected with a vertical line array and a moving upsweep source have been analyzed, in the frequency range 275–350 Hz. The source distance varied between 2.5 and 27 km. Due to the dynamic nature of the shallow water column and in particular the presence of soliton packets, the available environmental data used in matched-field processing was not sufficiently accurate for correctly localizing the source via this method. The mismatch between data and replica fields, particularly their phase differences, was significant. Source range errors were of the order of the source distance from the array, 2 to 20 km. In contrast, matched-mode processing yielded much better results. The modal time series were first estimated from the data, mode filtering was then used to eliminate noisy or nonparticipating modes and localization was finally performed. The source range errors varied between 200 m to 5 km.

Characterization of macroaggregates and photodegradation of their water soluble fraction

The analysis of macroaggregates of phytoplankton originating from the northern Adriatic using 13C and 1H nuclear magnetic resonance (NMR) spectroscopy showed the presence of long polymethylene chains, heteropolysaccharides and carboxyl groups. It is our belief that the polymethylene chains compose a part of bound carboxylic acids. Although it is possible that they are bonded in some other way, we favour this structure because it is commonly encountered in lipids. The water soluble fraction of macroaggregates were photolyzed using a photochemical reactor and exposure to sunlight. The photochemical transformations of aqueous solutions of natural macroaggregates and model mono- (glucose), di- (maltose) and polysaccharides (pullulan, laminarin) were followed colorimetrically at regular time intervals during light exposure using 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) and also using 1H NMR spectroscopy. Concentrations of monosaccharides produced from macroaggregates, pullulan and laminarin were increased under artificial light and sunlight. The photochemical degradation of macroaggregates in sunlight exhibits similar first order degradation kinetics to that under artificial light, but with a lower reaction rate. The 1H NMR studies of the irradiation products of pullulan and laminarin revealed a decrease in the signal of polysaccharide anomeric protons, suggesting degradation of the glycoside linkage. The prolonged irradiation of macroaggregates leads to decreasing monomer concentration and also suggests the degradation of produced monomers. The irradiation experiments on glucose confirmed this conclusion. Maltose, according to 1H NMR spectra, degrades to monomers which successively degrade. Photopolymerization can also occur after cleavage of glycoside linkages. These experiments showed that the northern Adriatic macroaggregates, mostly composed of heteropolysaccharides and polymethylene chains and originating from the cell wall, are photo-labile and their degradation proceeds through the cleavage of glycoside linkage and the subsequent degradation of monosaccharides produced. This photochemical degradation is significant and competitive with microbial degradation and could be important in reducing macroaggregate concentrations in shallow water columns of the northern Adriatic during summertime. Moreover, the lower molecular weight photoproducts can be subsequently used as substrates by microbes.

Microbial food web responses to phosphorus supply and solar UV radiation in a subarctic lake

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 12:239-249 (1997) - doi:10.3354/ame012239 Microbial food web responses to phosphorus supply and solar UV radiation in a subarctic lake Bergeron M, Vincent WF We examined the effects of solar ultraviolet radiation (UVR) and phosphorus enrichment on microbial food web structure in a subarctic oligotrophic lake (Lac à l'Eau Claire, Canada; latitude 56°10'N, longitude 74°30'W) using replicated, 20 l polyethylene containers incubated in situ. The experiments were run for between 6 and 9 d at the surface of the lake at 3 times during the summer open water period. Chlorophyll a (chl a) production of the >2 μm fraction of the phytoplankton community was stimulated by P; this response was reduced on average by 31% in the presence of UV-A, and by an additional 29% in the presence of UV-B. Conversely the <2 μm chl a fraction declined with P enrichment, but to a lesser extent in the presence of UV-B. Cell counts of picocyanobacteria showed a decrease under P enrichment, with significantly greater declines induced by UV-A and additionally by UV-B. The nanoflagellate community increased in cell concentration in response to P addition, but only in the absence of UV-A. Bacterial cell concentrations in the P enrichments remained close to or slightly above (up to 20%) the initial values, but sharply declined in the treatments without P addition; the positive effect of enrichment was not influenced by UV-A or by UV-B. This diverse array of responses implies that shifts in underwater UVR caused by changes in spectral penetration through the atmosphere (ozone depletion) or water column (changes in dissolved organic carbon) will influence microbial trophic structure as well as productivity within subarctic lakes. Such effects, however, will be limited to aquatic environments that are naturally exposed to high UVR such as shallow water columns or surface waters during diurnal stratification. Microbial food webs · Phosphorus · Polar · Subarctic lakes · UV Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 12, No. 3. Publication date: May 29, 1997 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 1997 Inter-Research.

Observations and model predictions of daily areal primary production in a eutrophic brackish water culture pond

Observations of daily gross primary production of oxygen per unit area in a eutrophic, brackish water shrimp culture pond over a 14-day period are compared with predictions from two models in order to assess the utility of the model approaches for ponds and to refine observational protocols and techniques for pond assessment. The models predicted rates (3.2 to 37.7 g O 2 m −2 d −1) which exceeded observations (4.7 to 15.7 g O 2 m −2 d −1) at all but the lowest light levels. Observed rates were also lower than other observations at similar light levels. These shortfalls are attributed to (1) the inadequacy of the method for estimation of community respiration as a component of gross production, in the absence of direct observation; and (2) the possibility of nutrient limitation of rates in the pond ecosystem. The models are sufficiently sensitive to chosen parameter values, and the day-to-day variation of the parameters in the ecosystem likely sufficiently variable, that daily determinations of parameters should be made when possible, with particular attention to timing and use of surface water. Field observations of daytime community respiration, and improved knowledge of its controlling factors and relationships, are important needs for the advancement of model treatment of photosynthesis in ponds. Eutrophic pond ecosystems have characteristics (vertical temperature structure resembling natural water bodies, complete light extinction within the shallow water column) which make them amenable to study as microcosms of some general aspects of aquatic primary production, particularly problems involving the prediction of daily areal rates from small-scale volume-based rate data.

Distribution of Trace Metals in the Surface Sediments of Two Pristine Subalpine Lakes in Taiwan

Abstract Sediment cores were collected from two remote subalpine lakes: the rather shallow (1.5 m) Little Ghost Lake at 2040 m elevation and the deeper, Great Ghost Lake (40 m) at 2150 m elevation. Different early diagenesis of metals were observed. the seasonally anoxic hypolimnion drives the annual iron redox cycle and causes the remobilization of metals in the mobile fractions of sediments in the Great Ghost Lake. These result in the redistribution of metals in the mobile fractions of sediment and poor correlation between metal concentrations. in the Little Ghost Lake, the shallow water column is always oxic with less change of metals in the mobile fractions of sediments. As a result, most metals have strong positive correlations with each other. The distributions of metal/Al ratios, total metal contents and acid-leached metal concentrations in the near-surface sediments of these two lakes suggest that the anthropogenic inputs from the atmospheric fallouts in recent decades are one of the major factors...

Benthic-pelagic interactions in shallow water columns: an experimentalist's perspective

Benthic-pelagic interactions in shallow water columns: an experimentalist's perspective

Immunofluorescence detection of the denitrifying strain Pseudomonas stutzeri (ATCC 14405) in seawater and intertidal sediment environments

A strain-specific immunofluorescence assay for enumeration of a marine denitrifying bacterium was developed and applied in the marine environment. The polyclonal antiserum for Pseudomonas stutzeri (ATCC 14405) did not react with other pseudomonads, other heterotrophs, or autotrophic nitrifying strains. The abundance of P. stutzeri in the shallow water column of Monterey Bay was less than 0.1% of the total bacterial abundance and decreased with depth, whereas the total bacterial abundance was variable and nearly constant with depth. P. stutzeri was also detected in the sediments of a microbial mat from Tomales Bay. The relatively low contribution of P. stutzeri to the total bacterial abundance in both environments implies that it is not a major component of the heterotrophic assemblage. This conclusion appears to hold for most other strains for which specific assays have been applied in the marine environment. The isolation of several different denitrifying strains from local marine environments implies that the culturable population is quite diverse, even in the absence of different selective enrichment media. Thus, strain specific immunofluorescence is of limited use in quantifying functional groups of bacteria. Conversely, they provide specific information on the diversity of natural populations and their relation to culturable strains.

Nitrogen cycling between sediment and the shallow-water column in the transition zone of the Potomac River and Estuary. II. The role of wind-driven resuspension and adsorbed ammonium

During periods of sediment resuspension, desorption of ammonium from sediment solids can be the major pathway for enriching the water column with the ammonium that is produced by bacterial degradation of organic matter in the bottom material. This hyopthesis is based on a three-year study of diffusive flux in the transition zone of the Potomac River at a site 35 m from the Virginia shore where the average water-column depth is approximately 1 m over sandy sediment. A diffusion-controlled sampler was used to collect water samples at the interface between the water column and sediment and at several tens of centimeters into the sediment. Interstitial water concentration gradients showed that diffusive flux of ammonium from the sandy shallow-water sediments was approximately 1% of the diffusive flux of ammonium from the silty channel sediments in the same zone of the Potomac River. Organic nitrogen and bound or adsorbed ammonium were the predominant nitrogen forms in the sediment. Adsorbed ammonium concentrations ranged from nondetectable to 3·7 μmol g −1 of sediment. Concentrations of adsorbed ammonium per gram of sediment were one to three orders of magnitude more than interstitial water ammonium concentrations. Desorption of ammonium from sediment solids appeared to be the controlling factor in the degree of water-column ammonium enrichment. In laboratory experiments that simulated sediment resuspension, 40–80% of the adsorbed ammonium predicted to desorb did so after approximately 30 min of mixing. Based on calculations for 1 m 2 to a depth of 4 cm, one resuspenion event lasting minutes could mix more ammonium into the water column from desorption of ammonium from sediment solids than could be delivered to the water column by diffusive flux from shallow-water sediments in 10–1000 days and would be comparable to enrichment by ammonium diffusive flux for 5–50 days from channel sediments in the same river zone.

Organotin concentrations in the Rivers Bure and Yare, Norfolk Broads, England

AbstractButyltin concentrations have been measured at eight freshwater sites (rivers and lakes) in the Norfolk Broads, UK, during 1986 and 1987. Tributyltin (TBT) was found in water samples from seven of the sites. Wherever TBT was present, dibutyltin and (usually) monobutyltin occurred. Levels of TBT exceeded 100 ng dm−3 in open stretches of both the Rivers Bure and Yare in 1986 and 1987. The highest concentration of TBT recorded for Wroxham Broad (a shallow lake) was 898 ng dm−3. Values of up to 3.26 μg dm−3 were measured in water samples taken from a marina. A depth profile for Wroxham Broad showed TBT to be uniformly distributed throughout the shallow water column. The results are discussed in relation to toxicity of TBT to freshwater organisms. Laboratory measurements of the degradation of TBT in freshwater from a marina gave a half‐life of six days at 20°C in the light.

The importance of a benthic ecosystem to the removal of radioactive trace elements from coastal waters

Abstract From radiotracer experiments in model ecosystems (MERL tanks), it was established that the first order removal rate constants (λw’s) of various radiotracers in shallow coastal water columns are closely related to their distribution ratios between suspended particles and seawater (Kd), the particle flux through the system and to season. The seasonal change in the removal rate constants for the different radionuclides was mainly controlled by the benthic faunal activities, which was responsible for extent and changes of bioturbation and resuspension rates of bottom sediments.

15N-depleted N2O as a product of nitrification

Recent interest in the role of nitrous oxide in the natural nitrogen cycle has focused on its production through the nitrification process1. Nitrous oxide depleted in 15N has been found in the shallow water column of the eastern tropical Pacific Ocean2, suggesting that 15N is depleted during N2O production. Here we report significant 15N depletion in N2O produced by bacterial nitrification, implying that N2O is produced via NO–2 rather than directly from NH+4 and that N2O should be very depleted in 15N where nitrification is the predominant production process for N2O. The magnitude of the isotope depletion is so large that this work should lead to further use of data on the natural abundance of 15N for assessing the sources and sinks of nitrogenous compounds.

Nitrogen cycling between sediment and the shallow-water column in the transition zone of the Potomac River and estuary. I. Nitrate and ammonium fluxes

A three-year study of seasonal variation in water-column and sediment nitrogen species was conducted in the transition zone of the Potomac River 35 m from the Virginia shore at a site with an average water-column depth of approximately 1 m over sandy sediment. A diffusion-controlled sampler was used to collect water samples from the water column, at the interface between the water column and sediment, and at several tens of centimeters into the sediment. Nitrate was the predominant dissolved nitrogen species in the water column. The importance of denitrification was inferred by nitrate fluxes which were directed into the sediment from the water column during approximately 75% of the sampling periods and ranged from 0·02 to 0·69 mmol m −2 day −1. Flux of nitrate from the sediment into the water column, ⩾0·1 mmol m −2 day −1, due possibly to nitrification in surficial sediment, occurred during one spring and two summer sampling periods. Ammonium fluxes were less than 0·1 mmol m −2 day −1 during 90% of the sampling periods. Of the ammonium fluxes that were >0·05 mmol m −2 day −1, all were fluxes into the sediment during sampling periods when sediment resuspension occurred, and all were into the water column during periods of calm. The mean value of ammonium flux (0·005 ± 0·05 mmol m −2 day −1) from the sandy, shallow-water sediments was two orders of magnitude less than the ammonium fluxes from the deeper, silty channel sediments in the same reach of the river. Diffusive flux calculations suggest that approximately one order of magnitude more nitrate than ammonium is cycled between the shallow-water column and the sandy sediment in the transition zone of the Potomac River.

Validating the Use of Radiotracers as Analogs of Stable Metal Behaviour in Enclosed Aquatic Ecosystem Experiments

Radiotracer experiments were carried out in enclosures in two lakes at the Experimental Lakes Area, North-western Ontario, to study the pathways of trace metal removal from the shallow water columns to the sediments of these lakes. As part of the larger experiment, stable carriers of Fe, Mn, and Zn were added individually to each of three enclosures. Rates of removal to sediments at pH 6.3 and backdiffusion after HCl addition to pH 4.8 of radiotracer 59Fe, 54Mn, and 65Zn were compared to the respective rates of their stable counterparts. Tracer removal and backdiffusion rates in enclosures which received stable carrier additions were further compared with the tracer behaviour in enclosures which received no carrier additions. Radiotracers and stable carriers were removed from the water column at similar rates at pH 6.3, and were remobilized at similar rates from the sediments when the pH of the water column was lowered to 4.8. The presence of the added stable carriers had no effect on the removal or remobilization of Mn or Zn. However, the removal of 59Fe from the water column was slowed slightly by the addition of Fe(III) carrier compared to removal in the other tubes, possibly due to the formation of colloidal phases. These results show that information on the rates of trace metal transport obtained using radiotracers is applicable to stable metal behavior in these freshwater systems. The use of radiotracers to study trace metal geochemistry under natural conditions is preferred to the addition of stable metals which may alter the physical and chemical properties of the suspended particulate matter as occurred after the addition of stable iron. Speciation studies showed that adsorption to ion exchange resins does not provide a reliable indication of the ionic form of metals in lake water.

Changes in chlorophyll a concentrations in a shallow water column during a solar eclipse : Vecchione, Michael, R.S. Maples and Richard Donahoe, 1986. Contr. mar. Sci. Univ. Texas, 29:37–44

Changes in chlorophyll a concentrations in a shallow water column during a solar eclipse : Vecchione, Michael, R.S. Maples and Richard Donahoe, 1986. Contr. mar. Sci. Univ. Texas, 29:37–44