Species body size distribution patterns of marine benthic macrofauna assemblages from contrasting sediment types

Author(s):  
David M. Parry ◽  
Michael A. Kendall ◽  
Ashley A. Rowden ◽  
Stephen Widdicombe

Species body size spectra have been constructed for macrofauna assemblages from four sites with contrasting sediment granulometry and heterogeneity in and around Plymouth Sound. The number of species and species turnover (β diversity) were higher on coarse sediment. While the fauna were distinct between sites, the median geometric size-class was conservative (class 14; 0.153–0.305 mg dry blotted weight). Only one site had significantly lower heterogeneity within the species size spectrum, yet this was the most heterogeneous sediment. As such, we were unable to reject the null hypothesis that species body size distribution patterns are conservative despite differences in sediment granulometry and heterogeneity.

2016 ◽  
Vol 73 (4) ◽  
pp. 471-476 ◽  
Author(s):  
Henrique C. Giacomini ◽  
Brian J. Shuter ◽  
Julia K. Baum

This special issue honours Rob Peters’ outstanding contributions to the field of aquatic ecology. It focuses on the size spectrum approach — in which individual organisms, rather than species, are the most basic biological unit — and highlights applications of this approach to fisheries management. The 21 papers in this issue cover three subject areas: (i) the use of size spectra to characterize variation in community structure, (ii) the development of size-based models of ecosystem dynamics to address fisheries questions, and (iii) applications of size-based theory to examine the consequences of variation in predator–prey size relationships, body size – trophic level relationships, and body size – life history relationships. The empirical studies herein demonstrate the utility of size spectra as indicators of population or community structure and for detecting impacts associated with environmental change. Future research focused on refining size-based sampling methods, standardizing metrics and analytical methods, understanding model sensitivity to the underlying assumptions, and comparative studies across ecosystems will enhance our ability to reliably interpret changes in size spectrum characteristics, thus facilitating their use as indicators of ecological change.


2008 ◽  
Vol 65 (1) ◽  
pp. 189-205 ◽  
Author(s):  
Christopher P. Woods ◽  
Mark T. Stoelinga ◽  
John D. Locatelli

Abstract Particle size spectra collected by the University of Washington’s Convair-580 research aircraft at a variety of altitudes and temperatures in winter frontal and orographic precipitation systems during the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE) are analyzed in this study. The particle size spectra generally appeared to conform to an exponential size distribution, with well-correlated linear fits between the log of the number concentration and particle diameter. When the particle size spectra were grouped according to the habit composition as determined from airborne imagery, significantly improved correlations between the size spectrum parameters and temperature were obtained. This result could potentially be exploited for specifying the size distribution in a single-moment bulk microphysical scheme, if particle habit is predicted by the scheme. Analyses of “spectral trajectories” suggest that the rime-splintering process was likely responsible for the presence of needle and column habit types and the positive shift in both N0s and λs at temperatures warmer than −10°C.


Author(s):  
Freddie Heather ◽  
Rick Stuart-Smith ◽  
Julia Blanchard ◽  
Kate Fraser ◽  
Graham Edgar

Amongst the more widely accepted general hypotheses in ecology is that community relationships between abundance and body size follow a log-linear size spectrum, from the smallest consumers to the largest predators (i.e., “bacteria to whales”). Nevertheless, most studies only investigate small subsets of this spectrum, due to extreme size classes that deviate from these linear expectations. In this study, we fit size spectra to field data from 45 rocky and coral reef sites along a 28° latitudinal gradient, and spanning 11 orders of magnitude in body size, from 3 μg to 150 kg. We found that 97% of the variation in abundance along this ‘extended’ size gradient was described by a single linear function across all sites. Moreover, consistent ‘wobbles’ were also observed, with subtle peaks and troughs in abundance along the spectrum, that related strongly to sea temperature and local site conditions.


2016 ◽  
Vol 96 (5) ◽  
pp. 1113-1118 ◽  
Author(s):  
Zheng Wang ◽  
Guanjian Xu ◽  
Henglong Xu

As an inherent function of a community, body-size spectrum has been increasingly used as a useful indicator in global ecological research. The colonization dynamics of biofilm-dwelling protozoa with regard to body-size spectrum were studied based on a 1-month baseline survey in coastal waters of the Yellow Sea, northern China. Samples were collected at time intervals of 1, 3, 7, 10, 14, 21 and 28 days from depths of 1 and 3 m. A total of seven body-size ranks were identified based on a trait hierarchy. The individual abundance of the protozoa at each body-size rank was well fitted to the logistic model equation. The body-size spectra showed a clear shift in probability density during the colonization period at both depths. The multivariate approach demonstrated that the temporal dynamics in body-size spectra of the protozoa may be divided into initial (1 day), transitional (3–7 days) and stable (10–28 days) stages during the colonization period. These results provide useful information for ecological research and monitoring programmes using biofilm-dwelling protozoa in marine ecosystems.


2021 ◽  
Author(s):  
Lisa-Marie Braun ◽  
Sandra Brucet ◽  
Thomas Mehner

AbstractTrophic interactions in the pelagic area of lakes and the opposing effects of fish feeding (top-down) and phytoplankton biomass (bottom-up) on zooplankton communities are central topics in limnology. We hypothesized that zooplankton size distributions should be a more sensitive approach to disentangle top-down and bottom-up effects than the commonly measured zooplankton biomass. We examined zooplankton size distributions from 148 samples collected during summer months in the upper and lower pelagic layers of a deep mesotrophic lake among 13 years of sampling. Top-down effects, namely fish size and biomass, and bottom-up effects, including water temperature and total phosphorus and chlorophyll a concentrations, were considered. To add robustness to our analyses, we expressed the zooplankton size distributions as size spectra based on log-binning, as continuous size spectra and by the size diversity, a measure that has been developed to mimic taxonomic diversity indices. Among numerous regressions tested, significant top-down or bottom-up effects could rarely been detected. Our results indicate that the overall zooplankton size distribution was not significantly affected by fish predation and lake productivity measured as total phosphorus or chlorophyll a concentration. However, we found negative correlations between fish biomass and the preferred zooplankton prey, including Bosmina longirostris, Daphnia cucullata and nauplii in the upper depth layer. However, due to their small body size, low biomass and therefore relative small contribution to the zooplankton size distribution, predation on preferred zooplankton species did not translate into a statistically significant modification of the entire size spectrum. Consequently, the size spectrum seems to be relatively robust against predation effects, but might reflect the lake-wide energy availability and transfer efficiency in the food web.


2020 ◽  
Vol 36 (5) ◽  
pp. 234-242
Author(s):  
Reuber Antoniazzi ◽  
Arleu B. Viana-Junior ◽  
Jaime Pelayo-Martínez ◽  
Liliana Ortiz-Lozada ◽  
Frederico S. Neves ◽  
...  

AbstractBoth decreases in compositional similarity with increasing geographic distances between sites (i.e. distance–decay relationship) and vertical stratification of species composition are key issues in ecology. However, the intersection between these two trends has scarcely been investigated. Here we use identical sampling methods in the canopy and at ground level in a tropical rainforest remnant on the coast of the Gulf of Mexico to evaluate, for the first time, a distance–decay relationship within vertical strata in insect assemblages. We found that the ant assemblage was vertically stratified; ant species richness was higher at ground level than in the canopy, and the species composition differed between the two vertical strata. Moreover, we observed that β-diversity increased with geographic distance at ground level, but not in the canopy strata. However, contrary to our prediction, there was less species turnover (lower β-diversity) between vertical strata than between trees. These findings may reflect differences in the dispersal capacity and nest habit of ants from each vertical stratum, and also habitat heterogeneity on the horizontal scale, e.g. the species of sampled trees. Our results illustrate the importance of sampling more than one vertical stratum to understand the spatial distribution patterns of biological diversity in tropical rainforests.


2020 ◽  
Vol 6 (16) ◽  
pp. eaay8641
Author(s):  
Graham H. Edwards ◽  
Terrence Blackburn

Chondritic meteorites, derived from asteroidal parent bodies and composed of millimeter-sized chondrules, record the early stages of planetary assembly. Yet, the initial planetesimal size distribution and the duration of delay, if any, between chondrule formation and chondrite parent body accretion remain disputed. We use Pb-phosphate thermochronology with planetesimal-scale thermal models to constrain the minimum size of the LL ordinary chondrite parent body and its initial allotment of heat-producing 26Al. Bulk phosphate 207Pb/206Pb dates of LL chondrites record a total duration of cooling ≥75 Ma, with an isothermal interior that cools over ≥30 Ma. Since the duration of conductive cooling scales with parent body size, these data require a ≥150-km radius parent body and a range of bulk initial 26Al/27Al consistent with the initial 26Al/27Al ratios of constituent LL chondrules. The concordance suggests that rapid accretion of a large LL parent asteroid occurred shortly after a major chondrule-forming episode.


2017 ◽  
Vol 63 (2) ◽  
pp. 8-16 ◽  
Author(s):  
Corrado Battisti ◽  
Marco Giardini ◽  
Francesca Marini ◽  
Lorena Di Rocco ◽  
Giuseppe Dodaro ◽  
...  

We reported a study on breeding birds occurring inside an 80 m-deep karst sinkhole, with the characterization of the assemblages recorded along its semi-vertical slopes from the upper edge until the bottom. The internal sides of the sinkhole have been vertically subdivided in four belts about 20 m high. The highest belt (at the upper edge of the cenote) showed the highest values in mean number of bird detections, mean and normalized species richness, and Shannon diversity index. The averaged values of number of detections and species richness significantly differ among belts. Species turnover (Cody’s β-diversity) was maximum between the highest belts. Whittaker plots showed a marked difference among assemblages shaping from broken-stick model to geometric series, and explicited a spatial progressive stress with a disruption in evenness towards the deepest belts. Bird assemblages evidenced a nested subset structure with deeper belts containing successive subsets of the species occurring in the upper belts. We hypothesize that, at least during the daytime in breeding season, the observed non-random distribution of species along the vertical stratification is likely due to (i) the progressive simplification both of the floristic composition and vegetation structure, and (ii) the paucity of sunlight as resources from the upper edge to the inner side of the cenote.


Author(s):  
Henglong Xu ◽  
Yong Jiang ◽  
Wei Zhang ◽  
Mingzhuang Zhu ◽  
Khaled A. S. Al-Rasheid ◽  
...  

The annual variations in body-size spectra of planktonic ciliate communities and their relationships to environmental conditions were studied based on a 12-month dataset (June 2007 to May 2008) from Jiaozhou Bay on the Yellow Sea coast of northern China. Based on the dataset, the body sizes of the ciliates, expressed as equivalent spherical diameters, included five ranks: S1 (5–35 μm); S2 (35–55 μm); S3 (55–75 μm); S4 (75–100 μm); and S5 (100–350 μm). These body-size ranks showed a clear temporal succession of dominance in the order of S2 (January–April) → S1 (May–July) → S4 (August–September) → S3 (October–December). Multivariate analyses showed that the temporal variations in their body-size patterns were significantly correlated with changes in environmental conditions, especially water temperature, salinity, dissolved oxygen concentration (DO) and nutrients. In terms of abundance, rank S2 was significantly correlated with water temperature, DO and nutrients, whereas ranks S4 and S5 were correlated with the salinity and nutrients respectively (P < 0.05). These results suggest that the body-size patterns of planktonic ciliate communities showed a clear temporal pattern during an annual cycle and significantly associated with environmental conditions in marine ecosystems.


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