Seasonal variations in a deep aggregation of Calanus pacificus in the Santa Barbara Basin

Ke, Osgood; Checkley, DM

doi:10.3354/meps148059

Cited by 45 publications

(35 citation statements)

References 13 publications

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“…approximately above 7000 to 10 000 ind. m -2 (Osgood & Checkley 1997, Sprules et al 1998. These high abundances are more typical for freshwater systems and were only observed very rarely (< 0.5%) in the present study.…”

Section: Methodscontrasting

confidence: 56%

Habitat selection by a marine copepod during the productive season in the Subarctic

Basedow¹,

Tande²,

Stige³

2010

Mar. Ecol. Prog. Ser.

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Few studies have analysed the depth distribution of marine zooplankton at high-resolution, and knowledge obtained from theoretical modelling studies predominates over that from empirical field studies. We analysed depth selection by the marine copepod Calanus finmarchicus during spring and summer in neritic and oceanic Subarctic regions. Data on hydrography and zooplankton distribution in the upper 100 m were collected at high resolution by a towed instrument platform equipped with CTD, fluorometer and an optical plankton counter. Four extensive field data sets covering time windows from 3 to 11 d during the productive season were analysed using generalized additive mixed models. Our main findings were that: (1) mean depth of older development stages (CV and adults) of C. finmarchicus was best predicted by biotic factors (depth of the fluorescence maximum and population density), while abiotic factors (depth of the pycnocline) were of secondary importance, (2) depth selection was similar in neritic and oceanic areas, and (3) there was no evidence for synchronous diel vertical migration. Our results suggest that copepods dynamically and consistently select their habitat (depth) based on food conditions and predators in a densitydependent manner. We conclude that ecological interactions may drive habitat choice of planktonic organisms even in highly fluctuating oceanic environments.

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Section: Methodscontrasting

confidence: 56%

Habitat selection by a marine copepod during the productive season in the Subarctic

Basedow¹,

Tande²,

Stige³

2010

Mar. Ecol. Prog. Ser.

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“…Sprat may prey on dormant copepods, but they do so in the daytime (Kaartvedt et al 2009); yet this winter the hypoxia-tolerant dormant copepods (Osgood and Checkley 1997) mainly occurred deeper, and in lower oxygen concentrations, than the sprat could tolerate most of the study period.…”

Section: Discussionmentioning

confidence: 99%

Seasonal and diel patterns in sedimentary flux of krill fecal pellets recorded by an echo sounder

Røstad

Kaartvedt

2013

Limnology & Oceanography

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We used a moored upward-facing 200 kHz echo sounder to address sedimentation of fecal pellets (FPs) from dielly migrating Meganyctiphanes norvegica. The echo sounder was located on the bottom at 150 m depth in the Oslofjord, Norway, and was cabled to shore for continuous measurements during winter and spring. Records of sinking pellets were for the first time observed with an echo sounder. Seasonal patterns of sedimentation of krill FPs were strongly correlated with data from continuous measurement of fluorescence, which illustrate the development of the spring bloom. Sedimenting particles were first observed as fluorescence values started to increase at the end of February and continued to increase until the bloom suddenly culminated at the end of March. This collapse of the bloom was detected on the echo sounder as a pulse of slowly sinking acoustic targets over a 2 d period. Prior to this event, there was a strong diel pattern in sedimentation, which correlated, with some time lag, with the diel migration of krill foraging at night near the surface. Pellet average sinking speeds ranged between 423 m d 21 and 804 m d 21 , with a strong relation to pellet target strength, which is an acoustic proxy for size. This novel approach shows that echo sounders may be a valuable tool in studies of vertical pellet flux and, thereby, carbon flux, providing temporal resolution and direct observation of the sedimentation process, which are not obtained from standard methods.

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“…Mesoscale eddies just south of Point Conception have been associated with hot spots for a number of seabird species (Yen et al, 2006). In the Santa Barbara Channel the deep bathymetry and associated hydrography leads to an incredibly dense aggregation of diapaus copepods (13,000 g wet weight (ww) m −3 ) from 450 to 500 meters in the spring and summer (Alldredge et al, 1984;Osgood and Checkley, 1997;Ohman et al, 1998). These levels are orders of magnitude higher than the estimated threshold density for foraging ∼0.6 g ww m −3 in basking sharks (Sims, 1999;Sims et al, 2006).…”

Section: Geographic Movements and Essential Habitatmentioning

confidence: 99%

Basking Shark (Cetorhinus maximus) Movements in the Eastern North Pacific Determined Using Satellite Telemetry

et al. 2018

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To fill data gaps on movements, behaviors and habitat use, both near-and offshore, two programs were initiated to deploy satellite tags on basking sharks off the coast of California. Basking sharks are large filter-feeding sharks that are second in size only to whale sharks. Similar to many megafauna populations, available data suggest that populations are below historic levels. In the eastern North Pacific (ENP) Ocean, the limited information on basking sharks comes from nearshore habitats where they forage. From 2010 to 2011, four sharks were tagged with pop-off satellite archival tags with deployments ranging from 9 to 240 days. The tags provided both transmitted and archived data on habitat use and geographic movement patterns. Nearshore, sharks tended to move north in the summer and prefer shelf and slope habitat around San Diego, Point Conception and Monterey Bay. The two sharks with 180 and 240 days deployments left the coast in the summer and fall. Offshore their paths diverged and by January one shark had moved to near the tip of the Baja Peninsula, Mexico and the other to the waters near Hawaii, USA. Vertical habitat use was variable both within and among individuals and changed as sharks moved offshore. Nearshore, most time was spent in the mixed layer but sharks did spend hours in cold waters below the mixed layer. Offshore vertical movements depended on location. The shark that went to Hawaii had a distinct diel pattern, with days spent at ∼450-470 m and nights at ∼250-300 m and almost no time in surface waters, corresponding with the diel migration of a specific portion of the deep scattering layer. The shark that moved south along the Baja Peninsula spent progressively more time in deep water but came to the surface daily. Movement patterns and shifts in vertical habitat and use are likely linked to shifts in prey availability and oceanography. Data collected indicate the potential for large-scale movements and the need for international dialogue in any recovery efforts.

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Seasonal variations in a deep aggregation of Calanus pacificus in the Santa Barbara Basin

Cited by 45 publications

References 13 publications

Habitat selection by a marine copepod during the productive season in the Subarctic

Habitat selection by a marine copepod during the productive season in the Subarctic

Seasonal and diel patterns in sedimentary flux of krill fecal pellets recorded by an echo sounder

Basking Shark (Cetorhinus maximus) Movements in the Eastern North Pacific Determined Using Satellite Telemetry

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