@article{,

title = {The relationship between algal blooms, fish kill incidents, and oxygen depletions along the Omani coast},

author = {Piontkovski, SA,Al-Gheilani, HMH,Jupp, B,Sarma, YVB,Al-Azri, AR},

issn = {0973-2667},

year  = {2012},

date = {2012-01-01},

journal = {International Journal of Oceans and Oceanography},

volume = {6},

number = {429},

pages = {145-177},

abstract = {A persistence of hypoxia is a common feature for the Sea of Oman, and the

western Arabian Sea. By using historical data complemented by ongoing

measurements, the relationship between the frequency of harmful algal

blooms, fish kill incidents, and oxygen depletions, was investigated. In the Sea

of Oman, the seasonal pattern exhibited a tendency of fish kill incidents to

increase, from January to November. In the western Arabian Sea, the pattern

was different- maximal occurrence of fish kill incidences was observed in

December and January. In 1988-2011, the number of harmful algal blooms

accompanied by fish kills was 4 times higher for the Sea of Oman (N= 91)

compared to the Arabian Sea coast (N= 22), whereas the total number of fish

kill incidents was about the same (22 versus 25). This means that the Arabian

Sea coast faced more frequent harmful blooms than the Sea of Oman. The Sea

of Oman coastal time series of the dissolved oxygen concentration implied a

steady decline throughout the year, from January to December. The fish kill

incidents in this region were mainly driven by oxygen depletions, whereas in

the Arabian Sea these incidents were mediated by the harmful algal blooms

along with the oxygen depletions. In analyzing the Omani coast as a whole,

the Ridge Multiple Regression Analysis implied the dissolved oxygen

concentration and monthly occurrence of algal blooms as the two variables

explaining 75% of the seasonal variations in fish kill incidents.},

keywords = {Arabian Sea, fish kill, Gulf of Oman, Harmful Algal Bloom, mass mortality, oxygen minimum, Sea of Oman, seasonal change, Sultanate of Oman},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Iodine chemistry reflects productivity and denitrification in the Arabian Sea: evidence for flux of dissolved species from sediments of western India into the OMZ},

author = {Farrenkopf,A.M.,Luther III,G.W.},

year  = {2002},

date = {2002-01-01},

journal = {Deep-Sea Research Part II},

volume = {49 },

number = {91},

pages = {2303-2318},

abstract = {Dissolved iodine species and total iodine concentrations were measured in the Arabian Sea during the Spring Intermonsoon of 1995. Two separate regimes of iodine chemistry are highlighted in this study: (1) the well-oxygenated surface layer (WOSL) where iodide concentrations were in the range of 158-558 nM, and (2) the oxygen minimum zone (OMZ) where total iodine concentrations [primarily as iodide and in excess to the oceanic iodine/salinity ratio of ~13] varied from ~200 to 950 nM. Iodine data in the WOSL of the Arabian Sea are contrasted with data from the Bermuda Atlantic Time-series Station (BATS), the Hawaii Ocean Time-series Station ALOHA (HOT), VERTEX in the Pacific and the Black Sea. Total iodine concentrations in excess of 400nM were observed in eastern portions of the OMZ. The eastern portion of the basin has a permanent denitrification zone as well as high concentrations of dissolved Mn2+ (d- Mn2+) and iodide. While there is precedent for high values of iodide and total iodine in several other isolated basins, this is the first report of such values in open-ocean waters. Potential sources of excess total iodine to the OMZ include advection along isopycnals, from hydrothermal vents or margin sediments; atmospheric deposition; and remineralization of sinking particulate organic iodine (POI) associated with elevated productivity in surface waters. We estimate that only 3.6% of the excess total iodine can result from remineralization of sinking POI from the WOSL to the OMZ. Advection from margin sediments off of India is the most plausible source of iodine to the OMZ and contributes ~96% of the total excess iodine to the OMZ. I- is maintained as the dominant form of iodine via in situ reduction of iodate by bacteria.},

keywords = {Arabian Sea, Atlantic, Hawaii, India, Oceanic, oxygen minimum, productivity},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Mesopelagic fishes of the Arabian Sea: distribution, abundance and diet of },

author = {Butler,M.,Bollens,S.M.,Burghalter,B.,Madin,L.P.,Horgan,E.},

year  = {2001},

date = {2001-01-01},

journal = {Deep-Sea Research Part II},

volume = {48},

number = {61},

pages = {1369-1383},

abstract = {Four species of predatory fishes - Chauliodus pammelas, Chauliodus sloani, Stomias afffnis and Stomias nebulosus - were collected on two cruises to the Arabian Sea during 1995. We present data on the abundances, horizontal and vertical distributions, and diet of these fishes. We also discuss briefly the importance of the oxygen minimum zone and predation on myctophid fishes to the ecology of these mesopelagic predators. Chauliodus pammelas and C. sloani appear to have only partially overlapping horizontal distributions in the Arabian Sea, with C. pammelas more common to the north and C. sloani more common to the south. Our data support previous results suggesting that diel vertical migration is the norm for these species, with smaller individuals usually nearer to the surface and larger individuals tending to stay deeper. In contrast to Chauliodus, Stomias affinis and S. nebulosus appear to have largely overlapping horizontal distributions in the Arabian Sea. However, they may have slightly di!erent vertical distributions, with S. affinis living slightly shallower (especially at night) than S. nebulosus. All four species spend most of their time in the oxygen minimum zone, entering the surface oxygenated waters (100-150 m) only at night (if at all). The diets of C. pammelas, C. sloani, and S. affinis consisted mainly of lantern fishes, Myctophidae, and other fishes. In contrast, S. nebulosus, the smaller of the two Stomias species, ate mostly copepods and other crustaceans. This differential feeding may allow the two Stomias species to co-occur. Three of these four stomiids appear to play an important role in predation on myctophid fish populations in the Arabian Sea.},

keywords = {abundance, Arabian Sea, diel, diet, diets, Distribution, ecology, feeding, migration, oxygen minimum, population, populations, predation, south},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Northern Arabian Sea variability from TOPEX/Poseidon altimetry data: an extension of the US JGOFS/ONR shipboard ADCP study},

author = {Kim,H-S,Flagg,C.N.,Howden,S.D.},

year  = {2001},

date = {2001-01-01},

journal = {Deep-Sea Research Part II},

volume = {48},

number = {134},

pages = {1069-1096},

abstract = {Sea-level anomalies (SLA) derived from the TOPEX/Poseidon (T/P) altimetry and inferred geostrophic currents within the northern Arabian Sea were examined for the period from March 1993 through November 1996. The primary objective of this study was to confirm and extend our understanding of the upper-ocean mesoscale variability observed in the shipboard acoustic Doppler current profiler (ADCP) data collected during the US JGOFS/ONR Arabian Sea Expedition (September 1994-January 1996). The accuracy of the T/P altimetry data (~3 cm rms) results in an uncertainty in the altimeter-derived velocities comparable to the ADCP measurement error. Thus the T/P data provide a reasonable method for extending studies of the mesoscale dynamics for the region. Comparison of the T/P-derived geostrophic velocities with concurrent ADCP data showed good correlation, with an r2 between 0.7 and 0.9 and rms di!erences of 10 cm s-1. The T/P data con"rm both the overall spatial and seasonal current patterns observed by the ADCP. The monsoonally averaged rms sea-level anomalies indicate a high degree of intraseasonal variation due to the generation of squirts, jets and eddies all along the coast, the variability of which increases in both intensity and areal extent during the Southwest Monsoon. The SLA data indicate amuch reduced degree of variability over the shelf. The SLA-derived eddy kinetic energy (EKE) fields are consistent with those derived earlier from the ADCP data in both distribution and magnitude. There is a large increase in EKE to the west and southwest and to a lesser extent to the south and a large area of relatively reduced eddy activity over much of the eastern and northern Arabian Sea. The area of reduced eddy activity coincides with the location of the most intense portions of the oxygen minimum zone found in the northern Arabian Sea. The spatial scales of the eddies responsible for the EKE distribution over the study area range between 200 and 500km in the nearshore region, decreasing to 100-200km o!shore. While there is significant energy variability in annual and semi-annual time scales, a substantial portion of the energy is found between 50 and 120 days, and the relative importance of this frequency band increases offshore. Spectra indicate a distinct break in the frequency content of the eddy field at about 15§N, with little energy at less than annual periods south of this latitude.},

keywords = {acoustic, Arabian Sea, Distribution, location, nearshore, oxygen minimum, south, spatial scale},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Mesozooplankton biomass, composition and distribution in the Arabian Sea during the Fall Intermonsoon: implications of oxygen gradients},

author = {Madhupratap,M.,Gopalakrishnan,T.C.,Haridas,P.,Nair,K.K.C.},

year  = {2001},

date = {2001-01-01},

journal = {Deep-Sea Research Part II},

volume = {48},

number = {146},

pages = {1345-1368},

abstract = {Mesozooplankton biomass and distribution of calanoid copepods were studied for the upper 500m between 3 and 21§N along an open-ocean transect in the Arabian Sea during the Fall Intermonsoon (September-October 1992, 1993). The region studied has strong gradients in the oxygen minimum zone (OMZ), being acutely deficient in oxygen in the north and with increasing concentrations towards the south. In the upper layers, mesozooplankton biomass was higher in the northern latitudes, above the thermocline, apparently avoiding the OMZ. In the deeper strata, relatively higher biomass was observed in the more oxygenated southern latitudes. Highest mesozooplankton biomass in open waters of the Arabian Sea was observed during the intermonsoon seasons. Calanoid copepods occurred at all depths, and surface-living species did not undertake conspicuous diel migrations, even when they occurred in the deeper waters of the more southern latitudes. A few species belonging to the families Metridinidae and Augaptilidae appeared to be characteristic of the poorly oxygenated mid-depths of the more northern latitudes. Seasonal variations in the composition of the copepod community were negligible. The evolution of the OMZ in the Arabian Sea and its implications are discussed.},

keywords = {Arabian Sea, depth, diel, Distribution, migration, oxygen minimum, seasonal variation, south, thermocline},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Processes controlling the distribution and cycling of manganese in the oxygen minimum zone of the Arabian Sea},

author = {Lewis,B.L.,Luther III,G.W.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47},

number = {400},

pages = {1541-1561},

abstract = {Vertical and horizontal distributions of dissolved and particulate manganese were investigated in the Arabian Sea (Northwestern Indian Ocean) during the 1995 Spring Intermonsoon period (March-April; US JGOFS Process Cruise 2; TN045). The region is characterized by an intense, basin-wide oxygen minimum zone (OMZ) that strongly influences the manganese distribution. In the OMZ, two distinct dissolved Mn (d-Mn) maxima were observed, at depths of 200-300 m and 600 m, respectively. The latter peak displayed concentration maxima of approximately 6 nanomolar and was largely confined to stations north of 19§N latitude (Stations N2-N7). This mid-depth maximum was associated with the low oxygen core of the OMZ ([O2] < ~ 2 æM), and appears to be maintained by a southward horizontal advective -diffusive flux of dissolved manganese from highly reducing Pakistan margin sediments, rather than input from the Oman Margin as previously suggested by Saager et al. (1989, Geochimica et Cosmochimica Acta, 53, 2259-2267). This signal was largely absent at stations along the southern transect, likely due to oxidative scavenging of d-Mn to the suspended particulate phase. Mid-depth particulate Mn maxima at some southern stations (Stations S4-S11) appear to be remnants of this feature. The upper d-Mn maximum (200-300 m depth) was more widely distributed than the 600 m peak, with d-Mn concentrations of ~ 3 to as high as 8 nm at most stations east of about 62§E longitude. The signal was everywhere correlated with the secondary nitrite maximum, at stations within the main denitrification zone delineated by Naqvi (1991). Nepheloid layers, presumably bacterial, also were associated with this depth interval. Particulate Mn profiles displayed corresponding concentration minima and low Mn/Al and reactive/refractory Mn ratios for this same depth interval, suggesting reductive dissolution of Mn-oxyhydroxides. These observations imply that in situ microbially mediated processes may be the predominant source of d-Mn in the upper OMZ, while horizontal advection is more important deeper in the water column.  },

keywords = {Arabian Sea, depth, Distribution, Indian Ocean, Oman, oxygen minimum, Pakistan},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Diel vertical migration of zooplankton and mesopelagic fish in the Arabian Sea},

author = {Luo,J.,Ortner,P.B.,Forcucci,D.,Cummings,S.R.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47 },

number = {145},

pages = {1451-1473},

abstract = {Acoustic (153 kHz ADCP and 12 kHz hull-mounted transducers) data and MOCNESS (MOC01 and MOC10) net tow samples collected in the Arabian Sea during the Spring Intermonsoon (April/May) and Southwest Monsoon (August) in 1995 documented substantial diel migrations of fish and zooplankton despite the year-round presence of an oxygen minimum ((0.2 ml l-1 at 125-150 m). Fish and zooplankton layers were distinguished by comparing 12 kHz sonar and 153 kHz ADCP backscatter data, which indicated that the strongly migrating layers were predominantly composed of fishes. Fish vertical migration speeds were independently estimated from the slopes of the volume scattering layers and from the vertical velocity components of the ADCP, yielding average speeds of 4 and 3 cm s-1 and maximum speeds of 13 and 10 cm s-1, respectively. A few migrating zooplankton layers were identified with an average speed of about 2 cm s-1 and maximum speeds as high as 8 cm s-1. Migration depths for both zooplankton and fish differed somewhat amongst stations and appeared to be related to local hydrographic conditions (principally the vertical gradients in DO and water temperature). Zooplankton displacement volumes at individual sites suggested that zooplankton biomass during the Southwest Monsoon could be as much as fivefold greater than during the Spring Intermonsoon. This observation was confirmed for the region in general by first deriving a relationship between ADCP backscatter intensity and daytime zooplankton biomass and then comparing the latter between cruises using daytime ADCP data taken along a 1500 km transect that extended from the coast of Somalia to the center of the northern basin.},

keywords = {acoustic, Arabian Sea, depth, diel, displacement, fish, migration, oxygen minimum, sonar, temperature, zooplankton},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Distribution, abundance, and feeding ecology of decapods in the Arabian Sea, with implications for vertical flux},

author = {Mincks,S.L.,Bollens,S.M.,Madin,L.P.,Horgan,E.,Butler,M.,Kremer,P.M.,Craddock,J.E.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47},

number = {158},

pages = {1475-1516},

abstract = {Macrozooplankton and micronekton samples were collected on two cruises in the Arabian Sea conducted during the Spring Intermonsoon period (May) and the SW Monsoon period (August) of 1995. Discrete depth samples were collected down to depths of 1000-1500 m. Quantitative gut content analyses were performed on four species of decapod shrimps, Gennadas sordidus, Sergia filictum, Sergia creber, and Eupasiphae gilesii, as well as on the pelagic crab Charybdis smithii. Of the shrimps, only S. filictum and S. creber increased significantly in abundance between the Spring Intermonsoon and SW Monsoon seasons. These four species were found at all depths sampled, and most did not appear to be strong vertical migrators. G. sordidus and S. filictum did appear to spread upward at night, especially during the SW Monsoon, but this movement did not include the entire population. S. creber showed signs of diel vertical migration only in some areas. All four shrimp species except, to some degree, S. creber lived almost exclusively within the oxygen minimum zone(150-1000 m), and are likely to have respiratory adaptations that allow them to persist under such conditions. Feeding occurred at all depths throughout these species' ranges, but only modest feeding occurred in the surface layer (0-150 m). G. sordidus appeared to feed continuously throughout the day and night. Estimated contribution of fecal material to vertical flux ranged from < 0.01-2.1% of particulate flux at 1000 m for the shrimps and 1.8-3.0% for C. smithii. (C) 2000 Published by Elsevier Science Ltd. All rights reserved. .},

keywords = {abundance, Arabian Sea, depth, Distribution, ecology, feeding ecology, migration, oxygen minimum, population, zooplankton},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Iron speciation in the Arabian Sea},

author = {Witter,A.E.,Lewis,B.L.,Luther III,G.W.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47},

number = {264},

pages = {1517-1539},

abstract = {Fe(III) speciation was measured in seawater collected as part of the United States Joint Global Ocean Flux (US JGOFS) Arabian Sea Process Study, Cruise TN045, March 14-April 10, 1995. The Fe-binding capacity of organic seawater ligands was measured in filtered seawater (<0.4 æm) collected from surface depths and throughout the oxygen minimum zone (OMZ). Seawaters from three stations on the southern line (S2, S9, and S11) were examined. Total Fe concentrations measured at the three sites ranged from: 1.25 ñ 0.21 nM to 1.30 ñ 0.01 nM (S2); 1.67 ñ 0.50 nM to 2.63 ñ 0.54 nM (S9); and 1.40 ñ 0.11 nM to 1.70 ñ 0.29 nM (S11). Cathodic stripping voltammetry (CSV) with 1-nitroso-2-napthol (1N2N) as the competitive ligand (pH 6.9) was used to determine conditional stability constants and Fe-binding ligand concentrations in seawater. Conditional stability constants for FeL complexes ranged from log KFeL = 21.6 ñ 0.1 to 22.5 ñ 0.9 at the three sites. Total ligand concentrations ranged from 1.47 ñ 0.06 nM to 6.33 ñ 1.16 nM over all sites, but increased by a factor of 2-3 from the surface to the oxygen minimum zone (OMZ), suggesting that Fe-binding ligands may be produced during organic matter degradation. Ligand concentrations were consistently higher than total iron concentrations at every site measured, with an average "excess" ligand concentration of 2.15 ñ 1.50 (n = 10). "Excess" ligand concentrations in the OMZ were 2 to 20 times higher than surface waters (upper 100 m). Formation-rate constants (kf ) and dissociation-rate constants (kd) between added Fe3+ and seawater ligands were measured using a kinetic approach at ambient seawater pH, allowing independent calculation of the conditional stability constant, since K = kf/kd. Using the kinetic approach, conditional stability constants ranged from log KFeL = 20.5 ñ 0.1 to 22.9 ñ 0.1. Although log K values are comparable in magnitude to those reported in the Pacific and Northwestern Atlantic Oceans, measured total ligand concentrations in the Arabian Sea are higher. This suggests that in areas that receive high Fe inputs through upwelling and/or atmospheric deposition, marine organisms may produce 'excess' ligands to keep Fe soluble in seawater for extended intervals.  },

keywords = {Arabian Sea, Atlantic, Atlantic Ocean, depth, marine, oxygen minimum, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Abundance and biomass of nano- and microplankton during the 1995 Northeast Monsoon and Spring Intermonsoon in the Arabian Sea},

author = {Dennett,M.R.,Caron,D.A.,Murzov,S.A.,Polikarpov,I.G.,Gavrilova,N.A.,Georgieva,L.V.,Kuzmenko,L.V.},

year  = {1999},

date = {1999-01-01},

journal = {Deep-Sea Research Part II},

volume = {46},

number = {87},

pages = {1691-1717},

abstract = {Phototrophic and heterotrophic nanoplankton (PNAN, HNAN; 2-20 æm protists) and microplankton (PMIC, HMIC; 20-200 æm protists and micrometazoa) are major components of the producer and consumer assemblages in oceanic plankton communities. Abundances and biomasses of these microorganisms were determined from samples collected along two transects during the Northeast Monsoon and Spring Intermonsoon process cruises of the US JGOFS Arabian Sea Program in 1995. Vertical profiles of these assemblages were strongly affected by the presence of a subsurface oxygen minimum layer. Abundances of all four assemblages decreased dramatically below the top of this layer. Depth-integrated (0-160 m) abundances and biomasses of nanoplankton and microplankton were of similar magnitude for most samples. Exceptions to this rule were primarily due to PMIC (mostly diatom) species which dominated phytoplankton assemblages at a few stations during each season. Depth-integrated biomasses for the combined nano- and microplankton averaged over all stations for each cruise were surprisingly similar for the Northeast Monsoon and Spring Intermonsoon seasons in this ecosystem (2.0 and 1.8 g C m-2 [170 and 150 m moles C m-2] for the two seasons, respectively). Nano- and microplankton biomass for these two time periods constituted a significant portion of the total amount of the particulate organic carbon (POC) in the water column. Summed over all stations, these assemblages constituted approximately 25-35% of the POC in the top 160 m of the northern Arabian Sea.},

keywords = {abundance, Arabian Sea, ecosystem, Oceanic, oxygen minimum, plankton},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {The oxygen minimum zone in the Arabian Sea during 1995},

author = {Morrison,J.M.,Codispoti,L.A.,Smith,S.L.,Wishner,K.,Flagg,C.,Gardner,W.D.,Gaurin,S.,Naqvi,S.W.A.,Manghnani,V.,Prosperie,L.,Gundersen,J.S.},

year  = {1999},

date = {1999-01-01},

journal = {Deep-Sea Research Part II},

volume = {46},

number = {174},

pages = {1903-1931},

abstract = {This paper focuses on the characteristics of the oxygen minimum zone (OMZ) as observed in the Arabian Sea over the complete monsoon cycle of 1995. Dissolved oxygen, nitrite, nitrate and density values are used to delineate the OMZ, as well as identify regions where denitrification is observed. The suboxic conditions within the northern Arabian Sea are documented, as well as biological and chemical consequences of this phenomenon. Overall, the conditions found in the suboxic portion of the water column in the Arabian Sea were not greatly different from what has been reported in the literature with respect to oxygen, nitrate and nitrite distributions. Within the main thermocline, portions of the OMZ were found that were suboxic (oxygen less than ~4.5 æM) and contained secondary nitrite maxima with concentrations that sometimes exceeded 6.0 æM, suggesting active nitrate reduction and denitrification. Although there may have been a reduction in the degree of suboxia during the Southwest monsoon, a dramatic seasonality was not observed, as has been suggested by some previous work. In particular, there was not much evidence for the occurrence of secondary nitrite maxima in waters with oxygen concentrations greater than 4.5 æM. Waters in the northern Arabian Sea appear to accumulate larger nitrate deficits due to longer residence times even though the denitrification rate might be lower, as evident in the reduced nitrite concentrations in the northern part of the basin. Organism distributions showed string relationships to the oxygen profiles, especially in locations where the OMZ was pronounced, but the biological responses to the OMZ varied with type of organism. The regional extent of intermediate nepheloid layers in our data corresponds well with the region of the secondary nitrite maximum. This is a region of denitrification, and the presence and activities of bacteria are assumed to cause the increase in particles. ADCP acoustic backscatter measurements show diel vertical migration of plankton or nekton and movement into the OMZ. Daytime acoustic returns from depth were strong, and the dawn sinking and dusk rise of the fauna were obvious. However, at night the biomass remaining in the suboxic zone was so low that no ADCP signal was detectable at these depths. There are at least two groups of organisms, one that stays in the upper mixed layer and another that makes daily excursions. A subsurface zooplankton peak in the lower OMZ (near the lower 4.5 æM oxycline) was also typically present; these animals occurred day and night and did not vertically migrate.},

keywords = {acoustic, Arabian Sea, density, depth, diel, Distribution, location, migrate, migration, occurrence, oxygen minimum, plankton, thermocline, zooplankton},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Feeding ecology of the copepod},

author = {Gowing,M.M.,Wishner,K.F.},

year  = {1998},

date = {1998-01-01},

journal = {Deep-Sea Research Part II},

volume = {45 },

number = {105},

pages = {2433},

abstract = {Feeding ecology of the calanoid copepod Lucicutia aff. L. grandis collected in the Arabian Sea at one station during the Spring Intermonsoon and during the Southwest Monsoon of 1995 was studied with transmission electron microscopy of gut-contents. Highest abundances of these animals occurred from 400 to 1100 m, near the lower interface of the oxygen minimum zone and at the inflection point where oxygen starts to increase. We expected that their gut-contents would include particles and cells that had sunk relatively undegraded from surface waters as well as those from within the oxygen minimum zone, and that gut-contents would differ between the Spring Intermonsoon and the more productive SW Monsoon. Overall, in both seasons Lucicutia aff. L. grandis was omnivorous, and consumed a variety of detrital particles, prokaryotic and eukaryotic autotrophs, gram-negative bacteria including metal-precipitating bacteria, aggregates of probable gram-positive bacteria, microheterotrophs, virus-like particles and large virus-like particles, as well as cuticle and cnidarian tissue. Few significant differences in types of food consumed were seen among life stages within or among various depth zones. Amorphous, unidentifiable material was significantly more abundant in guts during the Spring Intermonsoon than during the late SW Monsoon, and recognizable cells made up a significantly higher portion of gut-contents during the late SW Monsoon. This is consistent with the Intermonsoon as a time when organic material is considerably re-worked by the surface water microbial loop before leaving the euphotic zone. In both seasons Lucicutia aff. L. grandis had consumed what appeared to be aggregates of probable gram-positive bacteria, similar to those we had previously found in gut-contents of several species of zooplankton from the oxygen minimum zone in the eastern tropical Pacific. By intercepting sinking material, populations of Lucicutia aff. L. grandis act as a filter for carbon sinking to the sea floor. They also},

keywords = {abundance, Arabian Sea, depth, eastern tropical Pacific, ecology, feeding ecology, oxygen minimum, population, populations, zooplankton},

pubstate = {published},

tppubtype = {article}

}