@article{,

title = {Variability of water properties, heat and salt fluxes in the Arabian Sea, between the onset and wane of the 1995 southwest monsoon},

author = {Beal,L.M.,Chereskin,T.K.,Bryden,H.L.,Ffield,A.},

year  = {2003},

date = {2003-01-01},

journal = {Deep-Sea Research Part II},

volume = {50},

number = {42},

pages = {2049-2075},

abstract = {We investigate the variability of the circulation,water masses,heat and salt fluxes in the Arabian Sea over the course of the southwest monsoon. Two zonal sections taken along 8§30'N in 1995 as part of the Indian Ocean WOCE hydrographic program are used. The first was occupied in early June at the onset of the southwest monsoon winds,the second in late September,at the wane of the monsoon. The September section was found to be generally warmer (+0.32§C) and saltier (+0.04) than in June,despite a 50mm drop in mean sea level. Therefore,the common assumption that an increase in sea-surface height follows an increase in heat content (the hydrostatic response) does not hold. Instead,we conclude that the heat content increases due to the advection of Arabian Sea Surface Water and Red Sea Water onto the section from the north,and the drop in sea level is due to a loss of mass,rather than heat,from the water column. There are large uncertainties involved in diagnosing the heat-flux divergence across the Arabian Sea, because the seasonal variability of the water masses and circulation in the basin mean that our data are not representative of a steady state. We treat each section separately and find an oceanic heat export of -0.72PW in June and -0.19PW in September,implying a basin cooling rate of about -0.36PW in June and a slight heating of 0.12PW in September. In June the mass and heat balances are dominated by the Ekman transport and the Somali Current,with very flat density surfaces resulting in a small interior geostrophic transport. By September the Ekman transport has reduced,and it is primarily the interior transport that balances a strong Somali Current. There are two main overturning cells in June and September: A shallow one of approximate magnitude 15 Sv in June and 0 Sv in September, which reaches depths of no more than 500m and is driven by Ekman divergence at the surface; and a deep cell of magnitude 1 Sv representing a weak inflow and subsequent upwelling of Circumpolar Deep water. The deep cell implies a basin-averaged upwelling velocity of 3.2x10-5 cm s-1 through 2200 m.},

keywords = {Arabian Sea, density, depth, Indian Ocean, Oceanic, Red Sea, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Temporal variability of deep-sea zooplankton in the Arabian Sea},

author = {Koppelman,R.,Fabian,H.,Weikert,H.},

year  = {2003},

date = {2003-01-01},

journal = {Marine Biology},

volume = {142},

number = {138},

pages = {959-970},

abstract = {Mesozooplankton samples from two stations in the Arabian Sea (W AST, 4,050 in, 16 degrees 15'N, 60 degrees 20'E; CAST, 3,950 in, 14 degrees 30'N, 64 degrees 30'E) were collected from the surface down to 20 in above bottom during three monsoon periods: the autumn inter-monsoon in October 1995, the spring inter-monsoon in April 1997 , and the NE monsoon in February 1998. The main goal of this study is to enhance our knowledge on the effect of spatial and temporal differences in primary production and particle flux rates on the abundance and distribution of  mesozooplankton, with special attention to the deep sea. Literature data indicate episodically high rates of primary production and particle flux in the region during the sw monsoon and the autumn intermonsoon. Set in this context, the zooplankton showed an in-phase coupling in biomass and abundance with the primary production in the surface 150 in. In the mesopelagic realm (150-1,050 in), the seasonal coupling was less clear. In the bathypelagic zone, below 1 ,050 m, there was no evidence of in-phase coupling, though temporal differences in the distribution of zooplankton abundance and biomass with depth between seasons could be shown by an analysis of covariance and an a posteriori test. The results suggest that the bathypelagic community responds to increased particle flux rates, but with longer time gaps than in the epipelagic zone. This is probably due to longer development and response times of zooplankton in the cold, deep-water environment independent of possible lateral advection processes.},

keywords = {abundance, Arabian Sea, depth, Distribution, zooplankton},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Lipid biomarker  fluxes in the Arabian Sea, with a comparison to the equatorial Pacific Ocean},

author = {Wakeham,S.G.,Peterson,M.L.,Hedges,J.I.,Lee,C.},

year  = {2002},

date = {2002-01-01},

journal = {Deep-Sea Research Part II},

volume = {49 },

number = {495},

pages = {2265-2301},

abstract = {Fluxes and distributions of organic carbon (OC) and lipid biomarkers were measured in the western Arabian Sea as a function of season, depth, and distance from the coast of Oman during the US JGOFS Arabian Sea Process Study in 1994-1995. A strong seasonal pattern in OC and lipid flux is related to the annual monsoon cycle in the western Arabian Sea, with the highest fluxes measured during the Southwest Monsoon. Fluxes were greatly attenuated with depth in the water column and in surface sediments as remineralization effectively consumed particulate organic matter. A comparison of water-column fluxes with OC and lipid accumulation rates in sediments confirms that the water- sediment interface is a ''hot-spot'' for organic matter degradation. Biomarker compositions also varied seasonally and with distance offshore, reflecting seasonal and spatial succession of their biological sources and their subsequent export through the water column. Degradation of OC and biomarkers was extremely efficient, with only a tiny fraction (<1%) of their water-column flux preserved in sediments, although a range of compound-specific degradation efficiencies was apparent. This intense degradation has strong implications for contemporary carbon cycling and for interpreting sediment records for paleoceanographic reconstructions.},

keywords = {Arabian Sea, depth, Distribution, efficiency, Oman, Pacific Ocean},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Moored observations of upper-ocean response to the monsoons in the Arabian Sea during 1994-1995},

author = {Weller,R.A.,Fischer,A.S.,Rudnick,d.l.,Eriksen,C.C.,Dickey,T.D.,Marra,J.,Fox,C.,Leben,R.},

year  = {2002},

date = {2002-01-01},

journal = {Deep-Sea Research Part II},

volume = {49},

number = {253},

pages = {2195-2230},

abstract = {The role of surface forcing in the semiannual evolution of the upper-ocean temperature, salinity, and velocity fields in the Arabian Sea is examined. To do so, variability in the upper ocean in the central Arabian Sea was observed from an array of moorings deployed from October 1994 to October 1995. The Northeast (NE) Monsoon was characterized by moderate winds, clear skies, and dry air; sea-surface temperature (SST) dropped by 3§C; the ocean lost an average of 19.7Wm-2 and the mixed layer deepened by 100m in response. The Southwest (SW) Monsoon was accompanied by strong winds, cloudy skies, and moist air; the ocean gained an average of 89.5Wm-2 but SST dropped by 5.5§C and the mixed layer deepened to almost 80 m. The response to the NE Monsoon included daily cycling in the depth of the mixed layer in response to the diurnal cycle in the buoyancy forcing and a weak local, wind-driven response. Stronger windforcing during the SW Monsoon dramatically reduced diurnal restratification, and a clearer signal of local, wind-driven flow in the upper ocean was found. The strongest velocity signal in the upper ocean, however, was the flow associated with mesoscale geostrophic features that passed slowly through the moored array, dominating the current meter records in the first part of the NE Monsoon and again in the latter part of the SW Monsoon. One-dimensional heat and freshwater balances, which held at other times through the year, broke down during the passage of these features.},

keywords = {Arabian Sea, depth, salinity, temperature},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {An annual cycle of phytoplankton biomass in the Arabian Sea, 1994-1995, as determined by moored optical sensors},

author = {Kinkade,C.S.,Marra,J.,Dickey,T.D.,Weller,R.},

year  = {2001},

date = {2001-01-01},

journal = {Deep-Sea Research Part II},

volume = {48},

number = {137},

pages = {1285-1301},

abstract = {A surface-to-bottom mooring in the central Arabian Sea (15.5§N, 61.5§E) deployed from October 1994 to October 1995, included fluorometers, PAR irradiance sensors, Lu683 sensors, and a spectral radiometer. An annual cycle of phytoplankton biomass was determined by transforming signals from the optical sensors into chlorophyll a (chl a). Half-yearly phytoplankton blooms with water-column stratification were observed near the end of each monsoon, as well as biomass increases in response to mesoscale #ow features. During the Northeast Monsoon, the integrate water-column chl a rose from 15 to 25mg m-2, while during the Southwest Monsoon, chl a increased from 15 to a maximum >40mg m-2. We present an empirical relationship between the ratio of downwelling Ed443/Ed550 (blue to green wavelength ratio) and integral euphotic zone chl a determined by moored fluorometers (r2 = 0.73). There is a more significant relationship between Ed443/Ed550 measured at one depth in the water column (65 m) and the average vertical attenuation cofficient for PAR (KPAR) between 0 and 65m (r2 = 0.845). Because biofouling was a significant problem at times, data return from any one sensor was incomplete. However, optical sensor/data intercomparison helped fill gaps while permitting investigation of the temporal variability in observed phytoplankton biomass.  },

keywords = {Arabian Sea, chlorophyll, depth},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Physical forcing of biological productivity in the Northern Arabian Sea during the Northeast Monsoon},

author = {Kumar,S.P.,Ramaiah,N.,Gauns,M.,Sarma,V.V.S.S.,Muraleedharan,P.M.,Raghukumar,S.,Kumar,M.D.,Madhupratap,M.},

year  = {2001},

date = {2001-01-01},

journal = {Deep-Sea Research Part II},

volume = {48 },

number = {139},

pages = {1115-1126},

abstract = {Time-series observations at a nominally fixed location in the northern Arabian Sea (21§N, 64§E) during the Northeast Monsoon (winter, February) of l997 showed the prevalence of cold sea-surface temperatures (SST) and deep mixed layers resulting from winter cooling and convection. The covariation of nitrate concentrations in the surface layers and concentrations of chlorophyll a and primary production in the euphotic zone with mixed-layer depth (MLD) and wind suggests that carbon fixation was controlled primarily by physical forcing. Cooler waters during winter 1997 relative to winter 1995 were associated with deeper MLDs, higher nitrate concentrations, elevated primary productivity, and higher chlorophyll a concentrations, leading to the inference that even a 1§C decrease in SST could lead to significantly higher primary productivity. Satellite data on sea surface temperature (advanced very high-resolution radiometer; AVHRR) and TOPEX/POSEl- DON altimeter data suggest that this interannual variation is of basin-wide spatial scale. After the termination of winter cooling and subsequent warming during the Spring Intermonsoon, the Arabian Sea has low primary production. During the latter period, micro-organisms, i.e. heterotrophic bacteria and microzooplankton)-proliferate, a feeding mode through the microbial loop that appears to be inherent to mesozooplankton for sustaining their biomass throughout the year in this region.},

keywords = {Arabian Sea, chlorophyll, depth, feeding, lead, location, productivity, spatial scale, surface temperature, temperature},

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 = {Phycoerythrin-containing picocyanobacteria in the Arabian Sea in February 1995: diel patterns, spatial variability, and growth rates},

author = {Sherry,N.D.,Wood,A.M.},

year  = {2001},

date = {2001-01-01},

journal = {Deep-Sea Research Part II},

volume = {48 },

number = {225},

pages = {1263-1283},

abstract = {The abundance of phycoerythrin-containing picocyanobacteria in the surface mixed layer was measured both along-shore and offshore between 8 and 23 February 1995 in the Northwestern Arabian Sea. Water samples from 3m depth were taken at 2-h intervals and picocyanobacterial abundance and frequency of dividing cells were determined by epifluorescence microscopy. Cell counts showed an average diel change from a mid-day minimum of ~50'103 cells ml-1 to an evening maximum of ~180'103 cells ml-1. The diel change was greater than the differences observed between physically and spatially discrete water masses. By counting the frequency of dividing cells (FDC) and using a novel approach to estimating the length of time required to complete cell division, growth and loss rates were both estimated to be ~2.9 d-1 with daily turnover being 140% of the mean standing stock. If differences in the intrinsic population growth rate (æ) and the net rate of change in cell number (r) are assumed to be due to grazing, then grazing occurred throughout the day at a relatively constant rate (reflecting phytoplankton loss rates of ~0.12 h-1). Cell division rates peaked in the late afternoon and early evening. FDC decreased throughout the night, suggesting that dark-inhibition of cell division is weak or nonexistent in the picocyanobacteria we studied. While all cell types included in this study would be identified as Synechococcus by flow cytometry because they were small unicells with bright phycoerythrin fluorescence, morphological variability suggests that the community was actually taxonomically diverse and included cells other than Synechococcus, including Synechocystis. Despite this diversity, the strong diel patterns we observed persisted throughout the study region, suggesting that great care should be taken when interpreting picocyanobacterial survey data and experimental results that do not account for the e!ects of time-of-day.},

keywords = {abundance, Arabian Sea, depth, diel, growth, length, population, survey},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Geographical differences in seasonality of CZCS-derived phytoplankton pigment in the Arabian Sea for 1978-1986},

author = {Banse,K.,English,D.C.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47},

number = {322},

pages = {1623-1677},

abstract = {In situ measurements of phytoplankton chlorophyll in the Arabian Sea were taken largely along temporally and spatially unevenly distributed sections, scarce especially prior to the operation of NASA's Coastal Zone Color Scanner (CZCS). Herein, the CZCS pigment observations between late 1978 and mid-1986 north of 10§N, including the outer Gulf of Oman, are depicted for 14 subregions beyond the continental shelves as daily means, often only five days apart. To eliminate bias from electronic overshoot, the data were reprocessed with a more conservative cloud screen than used for NASA's Global Data Set. The pattern, derived from the older in situ observations, of one period with elevated chlorophyll almost everywhere during the Southwest Monsoon (SWM) and one additional late-winter bloom in the north, is confirmed. The differing nitrate silicate ratios in freshly entrained water in the central and northern Arabian Sea seem to lead to different succession and perhaps to differing vertical fluxes, and during winter favor blooms only in the north. The spatial pigment pattern in the outer Gulf of Oman is not an extension of that of the northwestern Arabian Sea. The seasonal physical forcing explains much of the timing of pigment concentration changes, but not the levels maintained over long periods. From the CZCS observations it is unclear whether the period of high phytoplankton productivity expected during the SWM in the open Arabian Sea lasts for about two or four months. During this entire season, chlorophyll values in the upper layers rarely exceed 1-2 mg m-3 outside the zone influenced by the Arabian upwelling. Near 15§N, however, fluxes into sediment traps at 3 km depth indicate an onset of high primary production very soon after the arrival of the SWM and suggest a long period of high production in the open sea. The partial temporal disconnect during the SWM between pigment changes in the upper part of the euphotic zone and of fluxes into the traps is disconcerting. For future modeling of plankton production in the open Arabian Sea, the use of two size classes of phytoplankton is recommended. The utility of satellite-derived pigment concentrations (as opposed to temporal changes of pigment) for testing such models is questioned.},

keywords = {Arabian Sea, chlorophyll, depth, Gulf of Oman, lead, Oman, plankton, productivity, timing, trap, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {The upper-ocean response to monsoonal forcing in the Arabian Sea: seasonal and spatial variability},

author = {Lee,C.M.,Jones,B.H.,Brink,K.H.,Fischer,A.S.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47},

number = {398},

pages = {1177-1226},

abstract = {Observations from four towed profiler surveys undertaken between December 1994 and October 1995 examine the seasonal and spatial variability of the upper ocean response to the Monsoon cycle in the Arabian Sea. Although observed atmospheric forcing agrees well with modern climatologies, cross-basin patterns of mixed-layer depth and water properties observed in 1994-1995 are not entirely consistent with an upper-ocean response dominated by Ekman pumping. During the winter monsoon, the mixed-layer deepens dramatically with distance offshore. Surface cooling intensifies with offshore distance, and a one-dimensional response dominated by convective overturning could explain observed wintertime mixed-layer depths. Except for waters associated with a filament extending o!shore from the Omani coast, mixed-layer depths and water properties show only modest cross-basin contrasts during the Southwest Monsoon. Filament waters differ from surrounding mid-basin waters, having shallow mixed-layers and water properties similar to those of waters upwelled near the Omani coast. In September, following the Southwest Monsoon, waters within 1000 km of the Omani coast have cooled and freshened, with marked changes in stratification extending well into the pycnocline. Estimates of Ekman pumping and wind-driven entrainment made using the Southampton Oceanographic Center 1980-1995 surface flux and the Levitus mixed-layer climatologies indicate that during the Southwest Monsoon wind-driven entrainment is considerably stronger than Ekman pumping. Inshore of the windstress maximum, Ekman pumping partially counters wind-driven entrainment, while offshore the two processes act together to deepen the mixed-layer. As Ekman pumping is too weak to counter wind-driven mixed-layer deepening inshore of the windstress maximum, another mechanism must act to maintain the shallow mixed-layers seen in our observations and in climatologies. Offshore advection of coastally upwelled water offers a mechanism for maintaining upper ocean stratification that isconsistent with observed changes in upper ocean water properties. Ekman upwelling will modulate wind-driven entrainment, but these results indicate that the primary mechanisms acting inshore of the windstress maximum are wind-driven mixing and horizontal advection.},

keywords = {Arabian Sea, depth, survey, Upwelling},

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 = {Pigment absorption and quantum yields in the Arabian Sea},

author = {Marra,J.,Trees,C.C.,Bidigare,R.R.,Barber,R.T.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47},

number = {149},

pages = {1279-1299},

abstract = {Carbon assimilation and optical properties were measured at several stations in the Arabian Sea, during the Spring Intermonsoon (March-April 1995) and the Northeast Monsoon (December 1995). Biological measurements, as a function of depth (z), included: 14C uptake (P), total daily (photosynthetically active) irradiance (EPAR), spectral irradiance, spectral absorption by phytoplankton, and a variety of HPLC-determined phytoplankton pigments. Phytoplankton absorption (aph) was optically weighted to the spectral quality of submarine irradiance. Absorption spectra based on particulates collected on filters were compared with spectra reconstructed from phytoplankton pigments. These two methods generally agreed, except in the blue region of the spectrum at intermediate and shallow depths. Quantum yield (f, on a daily basis) was estimated by non-linear regression from the relationship, P(z)/ ph(z)=f(EPAR)EPAR(z). Absorption by non-photosynthetic pigments in most cases causes a decrease in maximum realized quantum yield ranging from 30% to a factor of four. Generally, stations, with higher non-photosynthetic pigment absorption had lower maximum quantum yields but a greater ability to utilize high irradiances. The data suggest the hypothesis that adaptation, through absorption properties, is the primary determinant of the magnitude of photosynthetic quantum yield in phytoplankton.  },

keywords = {Arabian Sea, depth},

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 = {The Northeast Monsoon's impact on mixing, phytoplankton biomass and nutrient cycling in the Arabian Sea},

author = {Wiggert,J.D.,Jones,B.H.,Dickey,T.D.,Brink,K.H.,Weller,R.A.,Marra,J.,Codispoti,L.A.},

year  = {2000},

date = {2000-01-01},

journal = {Deep-Sea Research Part II},

volume = {47},

number = {254},

pages = {1353-1385},

abstract = {In the northern Arabian Sea, atmospheric conditions during the Northeast (winter) Monsoon lead to deep convective mixing. Due to the proximity of the permanent pycnocline to the sea surface, this mixing does not penetrate below 125 m. However, a strong nitracline is also present and the deep convection results in significant nitrate flux into the surface waters. This leads to nitrate concentrations over the upper 100 m that exceed 4 æM toward the end of the monsoon. During the 1994/1995 US JGOFS/Arabian Sea expedition, the mean areal gross primary production over two successive Northeast Monsoons was determined to be 1.35 gC/m2/d. Thus, despite the deep penetrative convection, high rates of primary productivity were maintained. An interdisciplinary model was developed to elucidate the biogeochemical processes involved in supporting the elevated productivity. This model consisted of a 1-D mixed-layer model coupled to a set of equations that tracked phytoplankton growth and the concentration of the two major nutrients (nitrate and ammonium). Zooplankton grazing was parameterized by a rate constant determined by shipboard experiments. Model boundary conditions consist of meteorological time-series measured from the surface buoy that was part of the ONR Arabian Sea Experiment's central mooring. Our numerical experiments show that elevated surface evaporation, and the associated salinization of the mixed layer, strongly contributes to the frequency and penetration depth of the observed convective mixing. Cooler surface temperatures, increased nitrate entrainment, reduced water column stratification, and lower near-surface chlorophyll a concentrations all result from this enhanced mixing. The model also captured a dependence on regenerated nitrogen observed in nutrient uptake experiments performed during the Northeast Monsoon. Our numerical experiments also indicate that variability in mean pycnocline depth causes up to a 25% reduction in areal chlorophyll a concentration. We hypothesize that such shifts in pycnocline depth may contribute to the interannual variations in primary production and surface chlorophyll a concentration that have been previously observed in this region.},

keywords = {Arabian Sea, chlorophyll, depth, growth, impact, lead, productivity, surface temperature, temperature, 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 = {The role of seasonal and diel changes in mixed-layer depth on carbon and chlorophyll distributions in the Arabian Sea},

author = {Gardner,W.D.,Gundersen,J.S.,Richardson,M.J.,Walsh,I.D.},

year  = {1999},

date = {1999-01-01},

journal = {Deep-Sea Research Part II},

volume = {46},

number = {97},

pages = {1833-1858},

abstract = {The e!ects of changes in the mixed-layer depth on the distribution of particulate organic carbon (POC) and chlorophyll a were examined in the Arabian Sea during the Northeast Monsoon (January and December), Spring Intermonsoon (February-March), and Southwest Monsoon (July and August) of 1995. POC distributions were derived from profiles of beam attenuation calibrated with POC, and chlorophyll a distributions were derived from calibrated fluorescence profiles. Depth of the seasonal mixed layer (Då of 0.125 kg m-3  from surface density) increased with distance offshore during both monsoons, especially in the southern Arabian Sea where the range was 10-80 m nearshore to 80-120 m offshore. The deepest seasonal mixed layers occurred during the Northeast Monsoon. During the Spring Intermonsoon the seasonal mixed layer was only 10-40 m. Variations in the depth of the diel mixed layer (Då of 0.03 kg m-3  from surface density) were up to 90 m during the Northeast Monsoon, but were seldom over 20 m during the Southwest Monsoon. During the Spring Intermonsoon when mixed layers and diel variations in the mixed layer were small, nutrients became depleted, producing oligotrophic conditions plus a strong deep chlorophyll a maximum (>2 mg chl m-3) below the mixed layer. The chlorophyll a maximum was centered at ~ 50 m, which is significantly beneath the effective depth of satellite color sensing. When mixing is active throughout the diel cycle, particulate organic carbon (POC) and chlorophyll distributions are quite uniform within the mixed layer. Nighttime increases in mixed layer depths can mix POC and chlorophyll a produced during the day downward and can entrain new nutrients to enhance primary production. Although mixing from diel variations may be effective in redistributing components within the mixed layer and may be an important mechanism for removing particles from the mixed layer, regional upwelling of nutrients and diatom blooms appear to dominate over diel mixed layer dynamics in the production and export of carbon in the Arabian Sea.},

keywords = {Arabian Sea, chlorophyll, density, depth, diel, Distribution, nearshore, Oceanic, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Monsoon-controlled export fluxes to the interior of the Arabian Sea},

author = {Honjo,S.,Dymond,J.,Prell,W.,Ittekkot,V.},

year  = {1999},

date = {1999-01-01},

journal = {Deep-Sea Research Part II},

volume = {46},

number = {388},

pages = {1859-1902},

abstract = {As a part of the US-JGOFS Arabian Sea Process Study (ASPS), we deployed a mooring array consisting of 16 Mark-7G time-series sediment traps on five moorings, each in the mesopelagic and interior depths in the western Arabian Sea set along a transect quasiperpendicular to the Omani coast. The array was deployed for 410 days to cover all monsoon and inter-monsoon phases at 4.25-, 8.5- or 17-day open-close intervals, all of which were synchronized at 17-day periods. Total mass flux, fluxes of organic, inorganic carbon, biogenic Si and lithogenic Al (mg m-2 day-1) were obtained from samples representing 667 independent periods. The average total mass fluxes estimated in the interior depth along this sediment trap array at Mooring Stations 1-5 (MS-1-5) during 1994-5 ASPS were 147, 235, 221, 164 and 63 mg m-2 day-1, respectively. Mass fluxes during the southwest (SW) Monsoon were always larger than during the northeast (NE) Monsoon at all divergent zone stations, but the difference was insignificant at the oligotrophic station, MS-5. Four major pulses of export flux events, two each at NE Monsoon and SW Monsoon, were observed in the divergent zone; these events dominated in quantity production of the annual mass flux, but did not dominate temporally. Export pulses were produced by passing eddies and wind-curl events, but the direct processes to produce individual export blooms at each station were diversified and highly complex. The onset of these pulses was generally synchronous throughout the divergent zone. Export pulses associated with specific biogeochemical signatures such as the ratio of elevated biogenic Si to inorganic carbon indicate a supply of deep water to the euphotic layer in varying degrees. The variability of mass fluxes at the oligotrophic station, MS-5, also represented both monsoon events, but with far less amplitude and without notable export pulses.},

keywords = {Arabian Sea, depth, pulses, trap},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Nitrogen dynamics during the Arabian Sea Northeast Monsoon},

author = {McCarthy,J.J.,Garside,C.,Nevins,J.L.},

year  = {1999},

date = {1999-01-01},

journal = {Deep-Sea Research Part II},

volume = {46},

number = {151},

pages = {1623-1664},

abstract = {This investigation focused on the weaker and less well understood of the two Arabian Sea monsoonal wind phases, the NE Monsoon, which persists for 3-4 months in the October to February period. Historically, this period has been characterized as a time of very low nutrient availability and low biological production. As part of the US JGOFS Arabian Sea Process Study, 17 stations were sampled on a cruise in January 1995 (late NE Monsoon) and, 15 stations were sampled on a cruise in November 1995 (early NE Monsoon). Only the southern most stations (10§ and 12§N) and one shallow coastal station were as nutrient-depleted as had been expected from the few relevant prior studies in this region. Experiments were conducted to ascertain the relative importance of different nitrogenous nutrients and the sufficiency of local regeneration processes in supplying nitrogenous nutrients utilized in primary production.  Except for the southern oligotrophic stations, the euphotic zone concentrations of NO3- were typically 5-10-fold greater than those of NO2- and NH4+. There was considerable variation (20-40-fold) in nutrient concentration both within and between the two sections on each cruise.  All nitrogenous nutrients were more abundant (2-4-fold) later in the NE Monsoon. Strong vertical gradients in euphotic zone NH4- concentration, with higher concentrations at depth, were common. This was in contrast to the nearly uniform euphotic zone concentrations for both NO3- and NO2-. Half-saturation constants for uptake were higher for NO3- (1.7 æmol kg-1 (s.d.=0.88, n=8)) than for NH4+ (0.47 æmol kg-1 (s.d.=0.33, n=5)). Evidence for the suppressing effect of NH4+ on NO3- uptake was widespread, although not as severe as has been noted for some other regions. Both the degree of sensitivity of NO3- uptake to NH4+ concentration and the half-saturation constant for NO3+ uptake were correlated with ambient NO3- concentration. The combined e!ect of high affnity for low concentrations of NH4+ and the effect of NH4+ concentration on NO3- uptake resulted in similarly low f-ratios, 0.15 (s.d.=0.07, n=15) and 0.13 (s.d.=0.08, n=17), for early and late observations in the NE Monsoon, respectively. Stations with high f-ratios had the lowest euphotic zone NH4+ concentrations, and these stations were either very near shore or far from shore in the most oligotrophic waters. At several stations, particularly early in the NE Monsoon, the utilization rates for NO2- were equal to or greater than 50% the utilization rates for NO3- . When converted with a Redfield C : N value of 6.7, the total N uptake rates measured in this study were commensurate with measurements of C productivity. While nutrient concentrations at some stations approached levels low enough to limit phytoplankton growth, light was shown to be very important in regulating N uptake at all stations in this study. Diel periodicity was observed for uptake of all nitrogenous nutrients at all stations. The amplitude of this periodicity was positively correlated with nutrient concentration. The strongest of these relationships occurred with NO3- . Ammonium concentration strongly influenced the vertical profiles for NO3- uptake as well as for NH4+ uptake. Both NO2- and NH4+ were regenerated within the euphotic zone at rates comparable to rates of uptake of these nutrients, and thus maintenance of mixed layer concentrations did not require diffusive or advective fluxes from other sources.  Observed turnover times for NH4+ were typically less than one day. Rapid turnover and the strong light regulation of NH4+ uptake allowed the development and maintenance of vertical structure in NH4+ concentration within the euphotic zone. In spite of the strong positive effect of light on NO2- uptake and its strong negative effect on NO2- production, the combined effects of much longer turnover times for this nutrient and mixed layer dynamics resulted in nearly uniform NO2- concentrations within the euphotic zone. Responses of the NE Monsoon planktonic community to light and nutrients, in conjunction with mixed layer dynamics, allowed for effcient recycling of N within the mixed layer. As the NE Monsoon evolved and the mixed layer deepened convectively, NO2- and NO3- concentrations increased correspondingly with the entrainment of deeper water. Planktonic N productivity increased 2-fold, but without a significant change the new vs. recycled N proportionality. Consequently, NO3- turnover time increased from about 1 month to greater than 3 months. This reflected the overriding importance of recycling processes in supplying nitrogenous nutrients for primary production throughout the duration of the NE Monsoon. As a result, NO3- supplied to the euphotic zone during the NE Monsoon is, for the most part, conserved for utilization during the subsequent intermonsoon period.  },

keywords = {Arabian Sea, depth, development, diel, growth, productivity},

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 = {Bacterial community composition during two consecutive NE Monsoon periods in the Arabian Sea studied by denaturing gradient gel electrophoresis (DGGE) of rRNA genes},

author = {Riemann,L.,Steward,G.F.,Fandino,L.B.,Campbell,L.,Landry,M.R.,Azam,F.},

year  = {1999},

date = {1999-01-01},

journal = {Deep-Sea Research Part II},

volume = {46},

number = {205},

pages = {1791-1811},

abstract = {Horizontal and vertical variations in bacterial community composition were examined in samples collected during two Joint Global Ocean Flux Study (JGOFS) Arabian Sea cruises in 1995. The cruises, 11 months apart, took place during two consecutive NE Monsoon periods (January and December). Bacteria were harvested by filtration from samples collected in the mixed layer, mid-water, and deep sea at stations across the study area. Total bacterial community genomic DNA was analyzed by PCR amplification of 16S rRNA gene fragments, followed by denaturing gradient gel electrophoresis (DGGE). In total, 20 DGGE bands reflecting unique or varying phylotypes were excised, cloned and sequenced. Amplicons were dominated by bacterial groups commonly found in oceanic waters (e.g., the SAR11 cluster of a-Proteobacteria and cyanobacteria), but surprisingly none of the sequenced amplicons were related to c-Proteobacteria or to members of the Cytophaga-Flavobacter-Bacteroides phylum. Amplicons related to magnetotactic bacteria were found for the first time in pelagic oceanic waters. The DGGE banding patterns revealed a dominance of ÷ 15 distinguishable amplicons in all samples. In the mixed layer the bacterial community was dominated by the same ÷ 15 phylotypes at all stations, but unique phylotypes were found with increasing depth. Except for cyanobacteria, comparison of the bacterial community composition in surface waters from January and December 1995 showed only minor differences, despite significant differences in environmental parameters. These data suggest a horizontal homogeneity and some degree of seasonal predictability of bacterial community composition in the Arabian Sea.},

keywords = {Arabian Sea, depth, DNA, dominance, Oceanic, PCR},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Remotely sensed features in the US JGOFS Arabian Sea Process Study},

author = {Shi,W.,Morrison,J.M.,B”hm,E.,Manghnani,V.},

year  = {1999},

date = {1999-01-01},

journal = {Deep-Sea Research Part II},

volume = {46},

number = {226},

pages = {1551-1575},

abstract = {TOPEX/POSEIDON altimeter data and wind data are used to calculate the geostrophic transport and Ekman transport in the northern Arabian Sea within the upper 500 m. In the summer, the upper 500-m layer in the northern Arabian Sea is horizontally divergent, with a transport going out of the northern Arabian Sea across 15.75§N reaching a maximum of 10 x 106 m3 s-1 in late June. In the winter, it is horizontally convergent, with a transport within the upper 500 m layer across 15.75§N reaching about 5 x 106 m3 s-1 into the northern Arabian Sea. The mean net transport for 1993-1995 out of the northern Arabian Sea across 15.75§N within the upper 500 m is estimated to be 0.74 x 106 m3 s-1. Most of the deep water upwelling across the 500 m depth, which compensates for the loss of waters in the upper 500-m layer, occurs in the eastern part of the northern Arabian Sea. The North Equatorial Current is found to deflect into the Arabian Sea during the NE Monsoon and the Spring Intermonsoon periods. In addition, estimates are made of the net transport into and out of the region encompassed by the US Joint Global Ocean Flux Study (JGOFS) Arabian Sea Process Study. The total transport out of the US JGOFS region is approximately 3.5-4.0 x 106 m3 s-1 in July of 1995 in the upper 500 m. Analysis of the mean sea surface height for the Arabian Sea shows a periodic change with the seasonal monsoon, with a typical depression of the ocean surface during the summer indicative of Arabian Sea cooling. The yearly change of the averaged sea surface height at 15.75§N is of the order of 15 cm. Rossby wave propagation also was observed at 15.75§N in the sea surface height fields.},

keywords = {Arabian Sea, depth, Upwelling},

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}

}

@article{,

title = {A southwest monsoon hydrographic climatology for the northwestern Arabian Sea},

author = {Brock,J.C.,McClain,C.R.,Hay,W.W.},

year  = {1992},

date = {1992-01-01},

journal = {Journal of Geophysical Research},

volume = {97},

number = {337},

pages = {9455-9465},

abstract = {This paper provides a detailed hydrographic climatology for the shallow northwestern Arabian Sea prior to and during the southwest monsoon, presented as multiple-year composite vertical hydrographic sections based on National Oceanographic Data Center historical ocean station data, Temperature and salinity measurements are used to infer the water masses present in the upper 500 m. The hydrographic evolution depicted on bimonthly sections is inferred to result from wind-driven physical processes. In the northwestern Arabian Sea the water mass in the upper 50 m is the Arabian Sea Surface Water. Waters from 50 to 500 m are formed by mixing of Arabian Sea Surface Water with Antarctic and Indonesian intermediate waters. The inflow of Persian Gulf Water does not significantly influence the hydrography of the northwestern Arabian Sea along the Omani coast. Nitrate has a high inverse correlation with temperature and oxygen in the premonsoon thermocline in the depth interval 5(}-150 m. During the southwest monsoon coastal upwelling off Oman and adjacent offshore upward Ekman pumping alter the shallow hydrography.},

keywords = {Antarctic, Arabian Sea, depth, oceanography, Oman, salinity, temperature, thermocline, Upwelling},

pubstate = {published},

tppubtype = {article}

}

@article{,

title = {Seasonality of phytoplankton chlorophyll in the central and northern Arabian Sea},

author = {Banse,K.},

year  = {1987},

date = {1987-01-01},

journal = {Deep-Sea Research},

volume = {34},

number = {35},

pages = {713-723},

abstract = {Marked seasonality of ship-based chlorophyll concentrations in the upper layers of the central and northern parts of the Arabian Sea is established for three hydrographically defined offshore areas.  A peak related to the southwest (summer) monsoon occurs, either with or without a northeast (winter) monsoon related peak.  Both appear to depend on the establishment of a deep mixed layer and the concomitant nutrient supply, but at any station the relation between pigment content and mixed-layer depth or nitrate concentration is usually obscure.},

keywords = {Arabian Sea, chlorophyll, depth},

pubstate = {published},

tppubtype = {article}

}