Near-bottom Zooplankton Research Articles

Visible Fidelity Collector of a Zooplankton Sample from the Near-Bottom of the Deep Sea

The multi-net visible fidelity zooplankton collector is designed to obtain near-bottom fidelity zooplankton. The collector is sent to the designated sampling location based on the information provided by the camera and altimeter. The host computer sends instructions to control the opening of the net port for sample collection and closing of the sampling cylinder cover after sampling. The collector contains three trawls so that three samples can be collected for each test, and environmental parameters can be collected simultaneously. After sampling, The sample maintains its fidelity, that is, maintaining the temperature and pressure of the seabed sample after sampling. Two experiments were carried out in the Western Pacific, and six bottles of zooplankton samples were successfully obtained. The development of a multi-net visible zooplankton collector is of great significance for the collection of near-bottom zooplankton.

New data on the diet of juvenile fish in the eastern Chukchi Sea

Data on feeding of underyearlings of arctic cod Boreogadus saida , pacific cod Gadus mac­rocephalus , saffron cod Eleginus gracilis , sand lance Ammodytes hexapterus , capelin Mallotus villosus , and other fish species were collected in the Chukchi Sea in August-September, 2017 in the framework of Arctic Integrated Ecosystem Survey (Arctic IES). In the time of survey, the eastern Chukchi Sea was free of the sea ice to 72о30′ N. Large aggregations of arctic cod were observed in the surveyed area. The diet of arctic cod juveniles and youngsters of other investi­gated species included both pelagic and near-bottom zooplankton, mainly copepods, euphausiids, oikoplevres, and juvenile decapods. The copepods Calanus glacialis and Calanus. hyperboreus dominated in the northern part of the surveyed area, being typical for the Arctic Ocean and Beau­fort Sea, and the species usual for the Bering Sea, as the copepods Calanus glacialis + Calanus marshallae , Eucalanus bungii , and Neocalanus cristatus , were in predominance in its southern part. Besides of these large-sized species, the species typical for the Alaska coastal waters were presented in the diet of juveniles, as the copepods Pseudocalanus spp., Centropages abdominalis , Acartia longiremis , Podon sp., Tortanus discaudatus , Epilabidocera amphitrites , and Eurytemora herdmani , as well as larvae of Polychaeta, Echinodermata, Cirripedia and veligers of Bivalvia. The arctic cod juveniles used the whole spectrum of prey but consumed mainly smalland medium-sized zooplankton, which biomass was relatively low in 2017: 21.8–243.5 mg/m3 in the southern part of the surveyed area and 5.1–83.0 mg/m3 in its northern part. Correspondingly, their feeding intensity was higher in the south: their stomach fullness was 98.7–67.5 ‱ in the south and 76.9–46.9 ‱ in the north; the mean daily ration was 4.2 % of the body weight in the south and 3.4 % in the north. These values are considered as low or medium, possibly the stock of arctic cod was too high for the feeding base, particularly in the northern area. From the other hand, the diets of arctic cod, saffron cod and sand lance were very similar in the areas of joint habitation, so competitive relations between these species could be assumed.

High temporal variability of zooplankton, but only weak evidence for a near-bottom effect on composition and distribution in the deep Levantine Basin, eastern Mediterranean

ABSTRACTAbundance and composition of the near-bottom zooplankton between 10 and 100 metres above the bottom (mab) were studied in the Levantine Basin, eastern Mediterranean, during four cruises of RV Meteor in June 1993, January 1998, April/May 1999 and October 2001. Copepoda made up 91% of all zooplankton caught. A strong dominance of one single species was observed on all cruises, with Lucicutia longiserrata reaching 50–90% of all Copepoda except in 1993, when Subeucalanus monachus was the most abundant species, with more than 90% of all Copepoda. The year 1993 was also exceptional in terms of total zooplankton abundance, being more than one order of magnitude higher than in the other years. Vertical differences in abundance and composition were small and did not indicate a near-bottom effect or a specialized benthopelagic zooplankton community in the layers sampled.

Near-bottom zooplankton aggregations in Kongsfjorden: implications for pelago–benthic coupling

Near-bottom zooplankton communities have rarely been studied despite numerous reports of high zooplankton concentrations, probably due to methodological constraints. In Kongsfjorden, Svalbard, the near-bottom layer was studied for the first time by combining daytime deployments of a remotely operated vehicle (ROV), the optical zooplankton sensor moored on-sight key species investigation (MOKI), and Tucker trawl sampling. ROV data from the fjord entrance and the inner fjord showed high near-bottom abundances of euphausiids with a mean concentration of 17.3 ± 3.5 n × 100 m−3. With the MOKI system, we observed varying numbers of euphausiids, amphipods, chaetognaths, and copepods on the seafloor at six stations. Light-induced zooplankton swarms reached densities in the order of 90,000 (euphausiids), 120,000 (amphipods), and 470,000 ind m−3 (chaetognaths), whereas older copepodids of Calanus hyperboreus and C. glacialis did not respond to light. They were abundant at the seafloor and 5 and 15 m above and showed maximum abundance of 65,000 ind m−3. Tucker trawl data provided an overview of the seasonal vertical distribution of euphausiids. The most abundant species Thysanoessa inermis reached near-bottom concentrations of 270 ind m−3. Regional distribution was neither related to depth nor to location in the fjord. The taxa observed were all part of the pelagic community. Our observations suggest the presence of near-bottom macrozooplankton also in other regions and challenge the current view of bentho–pelagic coupling. Neglecting this community may cause severe underestimates of the stock of pelagic zooplankton, especially predatory species, which link secondary production with higher trophic levels.

Deep-sea macroplankton distribution (at 400 to 2300 m) in the northwestern Mediterranean in relation to environmental factors

Changes in the composition and biomass distribution of deep-living zooplankton over wide gradients of depth (400–2300m) and longitude (~180km) have been analyzed in the Balearic Basin (western Mediterranean), seeking the environmental variables responsible for these changes. Zooplankton tends to aggregate at different levels of the water column (forming Deep Scattering Layers, DSL) and in the Benthic Boundary Layer (BBL). Macrozooplankton biomass and composition were analyzed along a transect performed in July 2010 in midwater (between ~350 and 450m) and near the bottom (at ~5–200mab), over soundings of 450–2263m, including the top of Valencia Seamount (at ~40° 25′ N–02° 42′ E, 1076m). Zooplankton changed significantly in composition at the mesoscale (~180km) in both the DSL and the BBL. Siphonophores and calanoid copepods were the most dominant deep zooplankton taxa, calanoids reaching higher abundance in the BBL (1761–5177 individuals/1000m3) than in the DSL (1568–1743 individuals/1000m3). There was a significant increase in near-bottom zooplankton biomass over the middle slope, at 1000–1300m, linked to an increase in scyphozoans and siphonophores (Lensia spp. and Abylopsis tetragona) with peaks of 1.5–2.0gWW/1000m3. The peak of near-bottom zooplankton at 1000–1300m coincided with the lowest temperatures (13.08°C) and maximum O2 concentration (4.40ml/l) near the bottom and below 1000m with higher records in near-bottom turbidity. Gelatinous zooplankton are the main prey in the diet of the demersal fish Alepocephalus rostratus in the western Mediterranean, fish responsible for the peak of megafauna biomass reported at around 1200–1400m in the deep Mediterranean and at similar depths in other oceanic areas (e.g. the NW Atlantic). We suggest that deep-sea environmental conditions can govern peaks of near-bottom zooplankton, as well as influence the structure of the demersal fish community.

Near-bottom zooplankton in the continental shelf and upper slope of Heraklion Bay (Crete, Greece, Eastern Mediterranean): observations on vertical distribution patterns

Near-bottom zooplankton sampled by a newly developed hyperbenthic sledge (TTSS2) on the continental shelf (50―200 m) and upper slope (300 m) of Heraklion Bay (Crete, Eastern Mediterranean) consisted of both meso- and macro-zooplankton. Meso-zooplankton was composed mainly of calanoid copepods and crustacean larvae, while macro-zooplankton consisted almost exclusively of chaetognaths. Results revealed that near-bottom zooplankton is found in very high densities close to the seabed and especially on or just a few centimetres above the sediment surface. Furthermore, near-bottom zooplankton abundance was significantly higher during the night than during the day implying that the performance of reversed diel vertical migration by these animals is probably due to the presence of predators that use tactile stimuli, rather than vision, to locate prey.

Biodiversity of the Near-Bottom Zooplankton of the Shallow Water Zone of the Kiev Reservoir and Its Spatial and Temporal Dynamics

Biodiversity of the Near-Bottom Zooplankton of the Shallow Water Zone of the Kiev Reservoir and Its Spatial and Temporal Dynamics

Structuredness of Aquatic Organisms' Communities as a Basis of Their Existence (a Case Study of Shallow-Water Near-Bottom Zooplankton)

Structuredness of Aquatic Organisms' Communities as a Basis of Their Existence (a Case Study of Shallow-Water Near-Bottom Zooplankton)

Near-Bottom Zooplankton of the Littoral Zone of the Dnieper Reservoirs and Its Seasonal Dynamics

Near-Bottom Zooplankton of the Littoral Zone of the Dnieper Reservoirs and Its Seasonal Dynamics

The near-bottom zooplankton at the abyssal BIOTRANS site, northeast Atlantic: composition, abundance and variability

The near-bottom zooplankton of the abyssal BIOTRANS site (water depth 4500 m was studied at two stations 11 nautical miles (nm) apart. Stratified sampling was conducted by means of a double MOCNESS at three depth layers 20, 50 and 100 m above bottom. The composition of the zooplankton showed a predominance of copepods, making up >50% of the total zooplankton abundance. Ostracods and chaetognaths were the most important non-copepods, displaying a slight increase towards the bottom. The variability of abundance and biomass was analysed statistically at different scales. Logarithmic coefficients of variation ranged from 29 to 187% for various taxa. Sampling at the two stations added significantly to the total variance for some taxa. By contrast, vertical gradients were mostly weak. Possible reasons for the observed variability are discussed.

Breaking internal waves on a Florida (USA) coral reef:a plankton pump at work?

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 166:83-97 (1998) - doi:10.3354/meps166083 Breaking internal waves on a Florida (USA) coral reef: a plankton pump at work? James J. Leichter1,*, Gregory Shellenbarger2, Salvatore J. Genovese3, Stephen R. Wing4 1Woods Hole Oceanographic Institution, Department of Biology, MS #34, Woods Hole, Massachusetts 02543, USA 21 Lincoln Street, Marblehead, Massachusetts 01945, USA 3Northeastern University, Marine Science Center, Nahant, Massachusetts 01908, USA 4Department of Marine Science, University of Otago, 304 Castle Street, Dunedin, New Zealand *E-mail: jleichter@whoi.edu Temperature, salinity, flow speeds, and plankton concentrations can be highly variable on the slope of Conch Reef, Florida Keys (USA), as warm surface water is mixed with cool, subsurface water forced onshore by broken internal waves. In August 1995 the water column seaward of the reef exhibited strong temperature and density stratification with a sharp pycnocline and associated subsurface chlorophyll a maximum layer at 45 to 60 m depth. On the reef slope, near-bottom zooplankton sampling at 22 to 28 m showed high concentrations of calanoid copepods, crab zoea, and fish larvae associated with upslope flow of cool, chlorophyll-rich water. In contrast to these periods of high concentrations, zooplankton concentrations were low during periods of long-shore and offshore flow of warm surface waters. Both the frequency of internal bore arrival and the mean duration of cool water events increase with increasing depth on the reef slope. Delivery of zooplankton to the reef is, therefore, also expected to increase with depth. A short-term settlement experiment showed increased settlement of serpulid worms at 20 and 30 m depth compared with 15 m, and a 15.5 mo transplant experiment showed significantly enhanced growth rates of the suspension-feeding coral Madracis mirabilis (Scleractinia: Pocilloporidae) at 30 m depth relative to growth at 15 or 20 m. Internal tidal bores appear to be a predictable, periodic source of cross-shelf transport to Florida coral reefs and an important influence on the spatial and temporal heterogeneity of suspended food particles and larval delivery to the benthos. Internal waves · Internal bores · Zooplankton · Transport Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 166. Publication date: May 28, 1998 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1998 Inter-Research.

Prey of Deep-water Hydra in Lake Superior

Specimens of Hydra attached to a soft-substrate bottom were collected from a manned submersible at a 275-m-deep station near the Keweenaw Peninsula in Lake Superior. Near-bottom zoo-plankton were collected to assess Hydra feeding preference. We identified and counted the zooplankton samples, and identified the zooplankton prey found in the Hydra. Of 86 Hydra, 21 contained remains of 23 prey of 4 zooplankton taxa. Compared with expected numbers based on the proportions of the net samples, these Hydra appeared to be feeding selectively, with a preference for larger zooplankton. The large calanoid copepod Limnocalanus macrurus was particularly selected. A very provisional estimate of the rate of Hydra predation on the bottom of Lake Superior is one prey per 4 days. The relatively constant environmental conditions, lack of commensals and predators, and the zooplankton food source suggest that the bottom of Lake Superior is a stable habitat for Hydra.