scholarly journals Main characteristics of arrowworms in the Bering Sea (species composition, distribution, biomass, production)

2021 ◽  
Vol 201 (2) ◽  
pp. 416-424
Author(s):  
К. M. Gorbatenko
Keyword(s):  
Species Composition ◽  
Biomass Production ◽  
Bering Sea ◽  
Mesh Size ◽  
Zooplankton Biomass ◽  
Total Zooplankton ◽  
Composition Distribution ◽  
Total Zooplankton Biomass ◽  
Epipelagic Layer ◽  
The Bering Sea

 Zooplankton was sampled from the epipelagic layer (0–200 m) in the Bering Sea using Jedae net (mouth 0.1 m2, mesh size 0.168 mm) in 1986–2018. Arrowworms were the most numerous predators, represented with 3 species: Parasagitta elegans, Eukrohnia hamata, and Pseudosagitta maxima. Their summary biomass was 215.7 mg/m3, on average (26.3 % of the total zooplankton biomass), and varied seasonally from 105.9 mg/m3 in winter to 311.8 mg/m3 in autumn. Parasagitta elegans dominated absolutely (> 99 % WW). Mean stock of this species was 64.36. 106 t; its seasonal yield was estimated as 22.1. 106 t in winter, 78.5. 106 t in spring, 191.9. 106 t in summer, and 130.3. 106 t in autumn, so its mean production was 422.8. 106 t WW per year.

scholarly journals Influence of net-cage fish farming on zooplankton biomass in the Itá reservoir, SC, Brazil

2012 ◽  
Vol 23 (4) ◽  
pp. 357-367 ◽  
Author(s):  
Bruna Roque Loureiro ◽  
Christina Wyss Castelo Branco ◽  
Evoy Zaniboni Filho
Keyword(s):  
Fish Farming ◽  
Dry Weight ◽  
Control Area ◽  
Zooplankton Biomass ◽  
Total Density ◽  
Total Zooplankton ◽  
Net Cage ◽  
Uruguay River ◽  
Cage Fish ◽  
Total Zooplankton Biomass

OBJECTIVES: This study aimed to verify the influence of net-cage fish farming on zooplankton biomass in the Itá reservoir (Uruguay River, Brazil). METHODS: Samples were collected monthly from October/2009 to May/2010 at the surface and at the bottom in two sampling stations, the net-cage area and in a control area using a Van Dorn bottle and a plankton net (68 µm). RESULTS: The Cladocera and Copepoda biomass was estimated by dry weight using a micro-analytical balance, and the Rotifera biomass by Biovolume. Total zooplankton biomass varied between 6.47 and 131.56 mgDW.m-3 Calanoida copepod presented the highest value of biomass (127.56 mgDW.m-3) and rotifers, despite having an important contribution to total density, showed a maximum biomass of 2.01 mgDW.m-3. Zooplankton biomass at the net-cage area surface was higher when compared with the control area during the months of October to January. However, the zooplankton biomass was similar at the bottom of the two areas throughout the studied period. From February until May, zooplankton biomass decreased in both sampling stations, a fact probably associated with the flushing of the reservoir, followed by an increase in water transparency and a decrease in chlorophyll-a concentration in the following months (February to May). CONCLUSIONS: The influence of fish farming on zooplankton biomass was detected at the surface of the net-cage area only from October to January. From February to May this influence was not found, probably by the influence of the flushing of the reservoir.

scholarly journals Seasonal variation in copepod abundance in relation to other zooplanktonic groups in the northwestern Mediterranean

1993 ◽  
Vol 62 (4) ◽  
pp. 215-226 ◽  
Author(s):  
Juliana H.M. Kouwenberg
Keyword(s):  
Seasonal Variation ◽  
Coastal Region ◽  
Zooplankton Biomass ◽  
High Abundance ◽  
Total Biomass ◽  
Total Zooplankton ◽  
Copepod Abundance ◽  
Bottom Depth ◽  
Total Zooplankton Biomass ◽  
Northwestern Mediterranean

Abundance of adult copepods and late copepodid stages from the upper 50 m in the Golfe du Lion (N.W. Mediterranean) was studied by the author in 1986, 1987, and 1988 for each season. Altogether 87 stations at 22 fixed locations were sampled in the frame of the multidisciplinary French/Spanish programme Pélagolion/Leopel in the near-coastal region (≤ 25 m bottom depth), the Rhone dilution zone, the neritic region (≤ 200 m bottom depth), and the oceanic region (200–2000 m bottom depth). Abundance of other zooplanktonic groups was estimated and total zooplankton biomass was determined for the upper 50 m. Copepod abundance was highest during September 1986 (all regions) and July 1987 (neritic). Total biomass was highest during July 1987 and May/June 1988, caused by high abundance of many other zooplankters.

Production of the Euphausiid Crustacean Thysanoëssa raschii in the Gulf of St. Lawrence

1977 ◽  
Vol 34 (3) ◽  
pp. 443-446 ◽  
Author(s):  
F. Berkes
Keyword(s):  
Field Data ◽  
Zooplankton Biomass ◽  
Total Zooplankton ◽  
Loss Of Weight ◽  
Annual Biomass ◽  
The Mean ◽  
Total Zooplankton Biomass ◽  
Population Numbers

From field data on growth and population numbers, production of Thysanoëssa raschii, excluding molts, was calculated to be about 1.8 mg dry wt∙m−3∙yr−1 in the Gulf of St. Lawrence. The mean annual biomass of T. raschii was 0.47 mg dry wt∙m−3, comprising about 1% of the total zooplankton biomass in the Gulf, and giving a production to biomass (P:B) ratio of about 4. Production and biomass were probably underestimated due to some sampler avoidance, lack of egg to nauplius–metanauplius interval of population production and loss of weight due to leaching in preserved samples.

Zooplankton and Trophic State Relationships in Florida Lakes

1983 ◽  
Vol 40 (10) ◽  
pp. 1813-1819 ◽  
Author(s):  
J. S. Bays ◽  
T. L. Crisman
Keyword(s):  
Trophic State ◽  
Size Structure ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Crustacean Zooplankton ◽  
Trophic State Index ◽  
Total Zooplankton ◽  
Eutrophic Lakes ◽  
Florida Lakes ◽  
Total Zooplankton Biomass

Zooplankton, including ciliated protozoans, were collected from 39 Florida lakes of widely ranging trophic state. Annual mean biomass values for different zooplankton groups were regressed against Carlson's Trophic State Index based on annual mean chlorophyll a concentration. Whereas total zooplankton biomass yielded a significant regression with increasing trophic state, microzooplankton (ciliates, rotifers, and nauplii) accounted for more of the relationship than macrozooplankton (cladocera, calanoids, and cyclopoids). Within the microzooplankton, the regression improved with decreasing body size. Macrozooplankton biomass exhibited a weak statistical relationship with lake trophic state, but the different component groups were variable in their response. The dominance within the zooplankton community shifts from macrozooplankton to microzooplankton with increasing trophic state, and the microzooplankton can constitute between 50 and 90% of the total zooplankton biomass in eutrophic lakes. Changes in zooplanktivore community structure with increasing trophic state show that whereas total fish biomass increases, dominance shifts from visually oriented predators, such as bass and bluegill, to pump filter-feeding planktivores, such as gizzard shad (Dorosoma cepedianum). While Florida zooplankton communities are similar in size structure to tropical communities, no statistically significant differences were found between empirical equations of crustacean zooplankton biomass and trophic state determined from temperate and Florida data bases.

scholarly journals Feeding of smoothtongue Leuroglossus schmidti in the Bering, Okhotsk Seas and adjacent waters of the Pacific Ocean

2016 ◽  
Vol 184 (1) ◽  
pp. 150-157
Author(s):  
Alexander Ya. Efimkin
Keyword(s):  
Bering Sea ◽  
Mesopelagic Fish ◽  
The North ◽  
Important Prey ◽  
The Pacific ◽  
Upper Epipelagic Layer ◽  
The Pacific Ocean ◽  
The North Pacific ◽  
Epipelagic Layer ◽  
The Bering Sea

Smoothtongue Leuroglossus schmidti is a small mesopelagic fish species common for subarctic waters. It rises to the upper epipelagic layer at night for feeding and preys mainly on euphausiids, copepods and amphipods. Its mean index of stomach fullness reaches 68 ‱ in the epipelagic layer, but it almost doesn’t feed deeper than 200 m, judging by a little food in the stomach. In the Bering Sea, euphausiids dominate in its diet and the portion of copepods is small. In the ​​Okhotsk Sea, each of these two groups provides a half of the diet. In the North Pacific, the portion of copepods is 63 % on average, euphausiids are the second important prey, and amphipods occur in the diet occasionally. Daily ration of smoothtongue is about 1.4 %.

scholarly journals Impact of changing oceanographic conditions on species composition and abundance of zooplankton on the fishing grounds at Cape Navarin and their importance for the Russian pollock fishery in the Bering Sea

2017 ◽  
Vol 189 (2) ◽  
pp. 103-120
Author(s):  
Yury I. Zuenko ◽  
Eugene O. Basyuk
Keyword(s):  
Species Composition ◽  
Bering Sea ◽  
Cold Water ◽  
Zooplankton Abundance ◽  
Zooplankton Species ◽  
Shape Dependence ◽  
Spawning Areas ◽  
Species Specific ◽  
Bering Sea Shelf ◽  
The Bering Sea

Seasonal and interannual variability of zooplankton in the area at Cape Navarin are considered on the base of long-term surveys. This area is the main fishing grounds for Russian pollock fishery in the Bering Sea. Species composition of zooplankton changes cardinally during the feeding period: large-size copepods prevail in summer, but euphausiids, mainly the krill Thysanoessa inermis - in autumn. Year-to-year changes of the zooplankton abundance are species-specific and driven by different environmental factors. The water circulation is crucially important for such allochtonous species as krill by transporting them from the spawning areas. Advection either from the south, i.e. from the continental slope (till 2006), or from the east and west, i.e. from the shelf (in 2007-2014), was observed in the last two decades that corresponded to replacing of relatively warm oceanographic regime by relatively cold regime and could be traced by dynamics of the ice cover and the cold water pool area on the eastern Bering Sea shelf. The advection from the slope provides the krill transport to the area at Cape Navarin, but conditions of the cold regime limit the transport. From the other hand, the cold oceanographic regime is favorable for reproduction of many zooplankton species, including krill, because of higher primary productivity. As the result, the krill and some other mass zooplankton species have a bell-shape dependence of their abundance on water temperature: they have the maximal biomass in relatively warm years within the cold periods and in relatively cold years within the warm periods. In the years with severe winters, the pollock starts its back migration early, in August-September because of seasonal depletion of copepods and lack of krill, while the years with warm winters are also unfavorable for long feeding of pollock in the Navarin area because of low abundance of many zooplankton species. «Moderate» conditions are optimal for long feeding of pollock in this area, when the Russian fishery continues here longer, till November-December, with the annual landings > 500,000 t (as in 1996-1999, 2001, 2007-2008).

scholarly journals Interannual dynamics of zooplankton in the Kola Section of the Barents Sea during the recent warming period

2019 ◽  
Vol 76 (Supplement_1) ◽  
pp. i10-i23
Author(s):  
Irina P Prokopchuk ◽  
Alexander G Trofimov
Keyword(s):  
Barents Sea ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Calanus Finmarchicus ◽  
The Arctic ◽  
Zooplankton Abundance ◽  
Total Zooplankton ◽  
The Barents Sea ◽  
Warming Period ◽  
Total Zooplankton Biomass

Abstract Our research focused on the analysis of interannual variability of zooplankton in the Kola Section (the Barents Sea) in the period of current warming in the Arctic basing on previously unpublished data. The zooplankton community was investigated based on the analysis of 240 plankton samples, collected in late May–early June 2009–2017. A total of 74 zooplankton taxa of nine phyla were identified in the plankton samples, but copepods were the most diverse and numerous taxonomic group. The biodiversity index varied considerably from year to year, but a stable tendency for the index to increase since the beginning of the period studied was observed. Copepods dominated in terms of abundance and biomass, comprising on average 73–96% of the total zooplankton abundance and 81–96% of the total zooplankton biomass. Calanus finmarchicus was the main zooplankton species utterly dominated by abundance and biomass (on average 92 and 97% respectively). Considerable differences in zooplankton abundance and biomass at different stations of the section were observed. Although the investigations were carried out during a warming period, interannual differences in zooplankton abundance and biomass were observed. Zooplankton biomasses were higher in the years with higher temperatures and stronger water inflow.

Zooplankton Seasonal Dynamics and Community Structure in Severn Sound, Lake Huron

1995 ◽  
Vol 30 (4) ◽  
pp. 673-692
Author(s):  
A.F. Gemza
Keyword(s):  
Community Structure ◽  
Zooplankton Community ◽  
Zooplankton Biomass ◽  
Point Sources ◽  
Total Zooplankton ◽  
Fish Community Structure ◽  
Calanoid Copepods ◽  
Diacyclops Thomasi ◽  
Annual Means ◽  
Total Zooplankton Biomass

Abstract The limnetic zooplankton of Severn Sound, a eutrophic embayment, were studied between 1978 and 1989. Forty-one species of zooplankton were identified from samples collected in the sound. Total zooplankton biomass ranged seasonally from a minimum of 3.9 mg/m3 at less eutrophic stations to over 1,625 mg/m3 at the most eutrophic sites. Annual means ranged from 38 to 373 mg/m3. At the most eutrophic sites the zooplankton community was dominated by the cladoceran Bosmina longirostris. Cyclopoid and calanoid copepods increased in dominance as conditions approached mesotrophy. Calanoid copepods were insignificant contributors at the eutrophic sites, averaging less than 3% of the total zooplankton biomass. Total zooplankton biomass declined with distance from shore and phosphorus point sources as conditions became less eutrophic. Significant empirical relationships (r>0.79) were measured between zooplankton biomass and total phosphorus and phytoplankton biovolume. Densities of several species, Eubosmina coregoni, Daphnia retrocurva and Diacyclops thomasi declined by over 50% during the 11-year period of study and may be related to a shift in fish community structure.

Sign in / Sign up

Export Citation Format

Share Document