Copepods size structure in various phases of a cold-core eddy - Normalised Abundance Size Spectra (NASS) approach.

Fluctuations in the abundance of anchovy (Engraulis spp.) and sardine (Sardinops sagax) are widespread in marine ecosystems, but the causes still remain uncertain. Differences between the planktonic prey availability, selectivity, and predation between anchovy and sardine have been suggested as factors influencing their dynamics. Using a dynamical multispecies size-spectrum model, we explore the consequences of changes in plankton size composition, together with intraguild predation and cannibalism, on the coexistence of these species. The shift towards smaller plankton has led to a reduction in the growth rate of both species. The effect was more deleterious on anchovy growth because it is unable to filter small particles. In model scenarios that included the effects of cannibalism and predation, anchovy typically collapsed under conditions favouring smaller sized plankton. The two species coexisted under conditions of larger sized plankton, although strong predation in conjunction with weak cannibalism led to the loss of sardine. The model provides new testable predictions for the consequences of plankton size structure on anchovy and sardine fluctuations. Further empirical work is needed to test these predictions in the context of climate change.

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Structure en taille des crustacés planctoniques d'un lac dimictique du Bouclier canadien

Canadian Journal of Zoology ◽

10.1139/z88-229 ◽

1988 ◽

Vol 66 (7) ◽

pp. 1570-1577

Author(s):

Lucie Martin ◽

Bernadette Pinel-Alloul

Keyword(s):

Seasonal Variation ◽

Annual Cycle ◽

Size Structure ◽

Principal Coordinate Analysis ◽

Size Spectra ◽

Fall Season ◽

Planktonic Crustaceans ◽

Bouclier Canadien ◽

Intermediate Linkage ◽

Chronological Clustering

From May 1981 to July 1982, 28 zooplankton samples were taken from the pelagic zone of Lake Cromwell, Quebec. Seasonal variation in the size structure of the planktonic crustacean community was studied using three different multidimensional analyses: intermediate linkage clustering, principal coordinate analysis, and chronological clustering. The results of these analyses showed the existence of distinct patterns in the size distribution of planktonic crustaceans during the annual cycle. During winter, the community was dominated by intermediate-sized organisms (0.51–0.60 mm), and by a few of larger size (0.96 mm). In springtime, nauplii appeared, and the larger size classes were reduced, giving the size spectra a characteristic shape. Small organisms (0.06–0.22 mm) dominated the population throughout the summer. The fall season was characterized by the opposite observation: small organisms slowly decreased in number while the intermediate classes (0.51–0.60 mm) increased in number to reach their peak in winter. These size–frequency patterns may be related to varying food levels and composition throughout the year.

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Zooplankton Community Structure in Hardwater Hypertrophic Lakes of Alberta

Water Science & Technology ◽

10.2166/wst.1993.0570 ◽

1993 ◽

Vol 27 (7-8) ◽

pp. 353-361 ◽

Cited By ~ 5

Author(s):

B. Pinel-Alloul

Keyword(s):

Phosphorus Content ◽

Size Structure ◽

Zooplankton Community ◽

Zooplankton Biomass ◽

Western Canada ◽

Zooplankton Abundance ◽

Lime Treatment ◽

Eutrophic Lakes ◽

Size Spectra ◽

Zooplankton Community Structure

Excessive concentrations of phosphorus are a common feature of hardwater eutrophic lakes in western Canada. Preliminary experimental lime treatment showed that this approach had a great potential to reduce phosphorus content and algal biomass. Therefore, two pairs of experimental and reference lakes were selected for a whole lake lime treatment and monitored for a full year prior to manipulation. This study presents the composition and size structure of the Zooplankton community of the lakes before treatment in order to assess the natural summer and inter-lake variations. Before lime treatment, seasonal means of total Zooplankton abundance and biomass ranged from 17 ± 8 to 127 ± 84 ind. L−1 and from 4 ± 2 to 138 ± 236 mg m−3, respectively. The two experimental lakes (Halftnoon and Lofty) were the richest in Zooplankton while the references lakes (Crooked and Jenkins) were the poorest. A total of 30 Zooplankton species (17 rotifers, 2 calanoids, 4 cyclopoids and 7 cladocerans) were recorded as well as 3 chaoborid species. The composition and size structure of Zooplankton varied between lakes and dates. Rotifers accounted for the majority of Zooplankton abundances (59-91%) while Cladocera (78-99%) or Copepoda (74%) in Crooked lake formed most of the Zooplankton biomass. Summer variations of the Zooplankton groups were described along with changes in size spectra. The temporal variation and the inter-lake differences in Zooplankton structure were discussed in relation to trophy, fish and invertebrate predation, and cyanophyte interactions.

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Warming alters community size structure and ecosystem functioning

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2012.0394 ◽

2012 ◽

Vol 279 (1740) ◽

pp. 3011-3019 ◽

Cited By ~ 102

Author(s):

Matteo Dossena ◽

Gabriel Yvon-Durocher ◽

Jonathan Grey ◽

José M. Montoya ◽

Daniel M. Perkins ◽

...

Keyword(s):

Size Structure ◽

Benthic Communities ◽

Taxonomic Composition ◽

Decomposition Rates ◽

Community Size ◽

Size Spectra ◽

Community Biomass ◽

Level Shifts ◽

Aquatic Mesocosms ◽

Total Community

Global warming can affect all levels of biological complexity, though we currently understand least about its potential impact on communities and ecosystems. At the ecosystem level, warming has the capacity to alter the structure of communities and the rates of key ecosystem processes they mediate. Here we assessed the effects of a 4°C rise in temperature on the size structure and taxonomic composition of benthic communities in aquatic mesocosms, and the rates of detrital decomposition they mediated. Warming had no effect on biodiversity, but altered community size structure in two ways. In spring, warmer systems exhibited steeper size spectra driven by declines in total community biomass and the proportion of large organisms. By contrast, in autumn, warmer systems had shallower size spectra driven by elevated total community biomass and a greater proportion of large organisms. Community-level shifts were mirrored by changes in decomposition rates. Temperature-corrected microbial and macrofaunal decomposition rates reflected the shifts in community structure and were strongly correlated with biomass across mesocosms. Our study demonstrates that the 4°C rise in temperature expected by the end of the century has the potential to alter the structure and functioning of aquatic ecosystems profoundly, as well as the intimate linkages between these levels of ecological organization.

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Analysis of size spectra off northwest Africa: a useful indicator in tropical areas?

ICES Journal of Marine Science ◽

10.1016/j.icesjms.2005.01.014 ◽

2005 ◽

Vol 62 (3) ◽

pp. 424-429 ◽

Cited By ~ 10

Author(s):

Kim A. Stobberup ◽

Cheikh A.O. Inejih ◽

Sory Traoré ◽

Carlos Monteiro ◽

Patrícia Amorim ◽

...

Keyword(s):

Size Structure ◽

Unit Area ◽

Demersal Fish ◽

Cape Verde ◽

Strong Increase ◽

Size Spectra ◽

Northwest Africa ◽

High Species Diversity ◽

Tropical Areas ◽

The Tropics

Abstract Changes in the size spectra of demersal fish communities off Cape Verde (1988, 1994), Guinea (1985–1995), and Mauritania (1987–2001) were studied. Intercepts and slopes showed opposite trends for Guinea and Mauritania, but were relatively stable in spite of a strong increase in landings per unit area. For Cape Verde, there were marked changes in size structure, seemingly inconsistent with the more moderate fishing pressure there. Changes in size structure do not seem to be suitable indicators of the effects of fishing in areas characterized by faster growth rates, small sizes, high species diversity, and complex interrelationships, such as the tropics.

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Response of Zooplankton Size Structure to Multiple Stressors in Urban Lakes

Water ◽

10.3390/w13162305 ◽

2021 ◽

Vol 13 (16) ◽

pp. 2305

Author(s):

Reliana Lumban Toruan ◽

Liah X. Coggins ◽

Anas Ghadouani

Keyword(s):

Body Size ◽

Environmental Variables ◽

Size Structure ◽

Negative Slope ◽

Total Biomass ◽

Size Spectra ◽

Urban Lakes ◽

Chl A ◽

Zooplankton Size ◽

Density And Biomass

Urban lakes are important environmental assets that contribute significant ecosystem services in urbanised areas around the world. Consequently, urban lakes are more exposed to anthropogenic pressures. Zooplankton communities play a central role in lake processes and, as such, are very sensitive to the impacts of human activities both through in-lake and catchment processes. Understanding their ecological function in urban lakes and how they respond to urbanisation is essential for environmental sustainability. In this study, we investigated the reliability of zooplankton size structure as indicators of anthropogenic stressors in urban lakes. We examined the relationship between environmental variables and zooplankton community size spectra derived as mean body size, density, and biomass. Our study showed that the overall mean body size was within the small size group ranged from 416 to 735 µm equivalent spherical diameter (ESD). Despite no significant difference in total zooplankton density between lakes, there was variability in the total density of the five different size classes. Total biomass was characterised by a significant proportion of size >750 µm. As the specific parameter of normalised biomass size spectra (NBSS), the slopes of the NBSS varied from moderate (−0.83 to −1.04) for a community with higher biomass of the larger size zooplankton to steeper slopes (from −1.15 to −1.49) for a community with higher biomass of smaller size. The environmental variables, represented by total phosphorus (TP) and chlorophyll a (chl-a), had a strong effect on zooplankton biomass and NBSS, where TP and chl-a were significantly correlated with the increase of total biomass and corresponded well with a less negative slope. Our results indicated that the community metric was sensitive to nutrient input and that size-based metrics have the potential to serve as key indicators for the management of urban lakes.

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Density-dependent effects as key drivers of intraspecific size structure of six abundant fish species in lakes across Europe

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2014-0508 ◽

2016 ◽

Vol 73 (4) ◽

pp. 519-534 ◽

Cited By ~ 16

Author(s):

Ignasi Arranz ◽

Thomas Mehner ◽

Lluís Benejam ◽

Christine Argillier ◽

Kerstin Holmgren ◽

...

Keyword(s):

Body Size ◽

Density Dependence ◽

Fish Species ◽

Size Structure ◽

Catch Per Unit Effort ◽

Lake Productivity ◽

Size Spectra ◽

Fish Size ◽

Density Dependent ◽

Size Diversity

We studied fish size structure by using mean size, size diversity, and the slope of linear size spectra of six common European fish species along large-scale environmental gradients. We further analyzed the response of these three size metrics to environmental variables and to density-dependent effects, i.e., relative estimates of abundance (catch per unit effort, CPUE). We found differences in the strength of main predictors of size structure between the six species, but the direction of the response was relatively similar and consistent for most of the size metrics. Mean body size was negatively related to temperature for perch (Perca fluviatilis), roach (Rutilus rutilus), and ruffe (Gymnocephalus cernuus). Lake productivity (expressed as total phosphorus concentration) and lake depth were also predictors of size structure for four of six species. Moreover, we found a strong density dependence of size structure for all species, resulting in lower mean body size and size diversity and steeper size spectra slopes when density dependence increases. This suggests that density dependence is a key driver of fish size structure.

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Comparison of biomass and size spectra derived from optical plankton counter data and net samples: application to the assessment of mesoplankton distribution along the Northwest and North Iberian Shelf

ICES Journal of Marine Science ◽

10.1016/j.icesjms.2004.03.018 ◽

2004 ◽

Vol 61 (4) ◽

pp. 508-517 ◽

Cited By ~ 25

Author(s):

Enrique Nogueira ◽

Gonzalo González-Nuevo ◽

Antonio Bode ◽

Manuel Varela ◽

Xosé Anxelu G Morán ◽

...

Keyword(s):

Size Structure ◽

Size Fraction ◽

Data Sets ◽

Size Spectra ◽

Pooled Data ◽

Spherical Diameter ◽

Student’S T ◽

The Relationship ◽

Counter Data ◽

Student’S T Test

Abstract Data from vertical net hauls and from a submersible optical plankton counter (OPC) were compared in terms of biomass and slope of the normalized biomass–size spectra (NB–SS), a proxy for the size structure of the community. The relationship between the estimates of biomass in the overlapping range sampled by both methods (0.2–2 mm equivalent spherical diameter (ESD)) was linear and not significantly different to 1 (BOPC:BNET=1.1±0.1, r2=0.84). However, the relationship varied depending on the size fraction considered; the ratio BOPC:BNET was 0.10±0.04 (r2=0.30), 0.8±0.2 (r2=0.66), and 2.4±0.5 (r2=0.64) for the size fractions 0.2–0.5, 0.5–1, and 1–2 mm ESD, respectively. The discrepancies between methods were presumably due to the combined effect of the limitations of the instrument in the lower detection limit and the errors in the volume of water sampled by the net for the smallest size fraction, and to net avoidance enhanced by clogging for the largest size fraction. The agreement between methods improved when the NB–SS of the different data sets were compared. The slope (b=−1.1) and the intercept (a=14.6) of the NB–SS integrated across stations were not significantly different (Student's t-test) for the linear model fitted to net samples, OPC data, or pooled data from both methods. Station by station, the slopes of the NB–SS from the net (bNET) and the OPC (bOPC) were not significantly different in 61% of the stations. This percentage increased to 78% when the comparison was limited to the mesoplankton size range. As an example of the applicability of the OPC, we showed the distribution of mesoplankton biomass and size structure along the NW and N Iberian Shelf during the winter–spring transition of 2002 and its relationship with the hydrographic scenario.

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Spring-time zooplankton size structure over the continental shelf of the Bay of Biscay

Ocean Science Discussions ◽

10.5194/osd-10-2207-2013 ◽

2013 ◽

Vol 10 (6) ◽

pp. 2207-2254 ◽

Cited By ~ 1

Author(s):

P. Vandromme ◽

E. Nogueira ◽

M. Huret ◽

Á Lopez-Urrutia ◽

G. González-Nuevo González ◽

...

Keyword(s):

Size Structure ◽

Mesh Size ◽

Trophic Levels ◽

Equivalent Diameter ◽

Special Focus ◽

Bay Of Biscay ◽

Data Set ◽

Size Spectra ◽

Explanatory Variables ◽

Zooplankton Size

Abstract. Linking lower to higher trophic levels requires a special focus on the pivotal role played by mid-trophic levels, i.e. the zooplankton. One of the most relevant information on zooplankton in term of fluxes of matter lies in its size structure. We present here an extensive dataset of size measurements covering part of the western European shelf and slope, from the Galician coast to the Ushant front, during springs from 2005 to 2012. Zooplankton size spectra were estimated using both measurements carried out in situ by the Laser-Optical Plankton Counter (LOPC, 816 records) and WP2 net (200 μm mesh size) samples scanned following the ZooScan methodology and image analysis (a total of 89 samples were analyzed). The LOPC counts and sizes all particles in the range 100 to 2000 μm of spherical equivalent diameter (ESD) whereas the WP2/ZooScan allows the counting, sizing and identification of zooplankton from ~400 μm ESD. The difference between the LOPC (all particles) and the WP2/ZooScan (zooplankton only) is assumed to provide the size distribution of non-living particles whose descriptors are further related to a set of explanatory variables (including physical, biological and geographic descriptors). A statistical correction based on these explanatory variables is then applied to LOPC measurements to removed the part due to non-living particles and estimate zooplankton size spectra. This extensive data set provides a new look at regional and inter-annual variability of the pelagic ecosystem of the Bay of Biscay.

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Fishing degrades size structure of coral reef fish communities

10.7287/peerj.preprints.2118 ◽

2016 ◽

Author(s):

James PW Robinson ◽

Ivor D Williams ◽

Andrew M Edwards ◽

Jana McPherson ◽

Lauren Yeager ◽

...

Keyword(s):

Coral Reef ◽

Reef Fish ◽

Fish Community ◽

Size Structure ◽

Fish Communities ◽

Fish Biomass ◽

Community Size ◽

Size Spectra ◽

Coral Reef Ecosystems ◽

Total Fish

Fishing pressure on coral reef ecosystems has been frequently linked to reductions of large fishes and reef fish biomass. Associated impacts on overall community structure are, however, less clear. In size-structured aquatic ecosystems, fishing impacts are commonly quantified using size spectra, which describe the distribution of individual body sizes within a community. We examined the size spectra of coral reef fish communities at 38 US-affiliated Pacific islands, spanning from near pristine to highly human populated. Reef fish community size spectra slopes ‘steepened’ steadily with increasing human population and proximity to market due to a reduction in the relative biomass of large fishes and an increase in the dominance of small fishes. In contrast, total fish community biomass was substantially lower on inhabited islands than uninhabited ones, regardless of human population density. Comparing the relationship between size spectra and reef fish biomass, we found that on populated islands size spectra steepened linearly with declining biomass, whereas on uninhabited islands size spectra and biomass were unrelated. Size spectra slopes also were steeper in regions of low sea surface temperature but were insensitive to variation in other environmental and geomorphic covariates. In contrast, reef fish biomass was highly sensitive to biophysical conditions, being influenced by oceanic productivity, sea surface temperature, island type, and habitat complexity. Our results suggest that community size structure is more robust than total fish biomass to increasing human presence and that size spectra are reliable indicators of exploitation impacts across regions of different fish community compositions, environmental drivers, and fisheries types. Size-based approaches that link directly to functional properties of fish communities, and are relatively insensitive to abiotic variation across biogeographic regions, offer great potential for developing our understanding of fishing impacts in coral reef ecosystems.

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