scholarly journals SECONDARY PRODUCTION OF Scolelepis goodbodyi (POLYCHAETA: SPIONIDAE) IN A TROPICAL SANDY BEACH IN THE SOUTHWESTERN ATLANTIC, BRAZIL

2020 ◽  
Vol 24 (04) ◽  
pp. 819-833
Author(s):  
Luciana Sanches Dourado Leão ◽  
◽  
Abílio Soares-Gomes ◽  
José Roberto Botelho de Souza ◽  
Cinthya Simone Gomes Santos ◽  
...  
Keyword(s):  
Growth Rate ◽  
Secondary Production ◽  
Environmental Variability ◽  
Trophic Levels ◽  
Southwestern Atlantic ◽  
Web Studies ◽  
Marine Habitats ◽  
Production Values ◽  
Annual Biomass ◽  
Density And Biomass

The secondary production is the result of the functional response of populations subject to various environmental factors. Marine habitats vary in terms of quantity and quality of food supply, and the use of secondary production values, as well as renewal rates (P/B), may be used as estimates for understanding the incorporation of organic matter and energy per unit, population or community in each area. This estimative was performed for the population of Scolelepis goodbodyi in a tropical beach in the Southwestern Atlantic, located in an upwelling area. A comparison of Spionidae and non-spionid populations from different latitudes was also done. The Mass Specific Growth Rate method (MSGR) and the Production/Biomass ratio (P/B) were used to estimate the somatic annual production and average annual biomass. The mean density and biomass were 16.38 ind. m-2 and 2.78 g AFDW m-2,respectively. The secondary production and P/B were 8.3 g AFDW m-2 y-1 and 2.98 y1, respectively. The growth rate in weight was greater for the small size than the large size classes. The largest individuals (W3C = 1.0 mm) showed the lowest biomass and secondary production values. The observed high rates of secondary production and P/B suggest that this S. goodbodyi population can transfer large amounts of biomass to higher trophic levels of the local food web. Studies of the secondary production of spionidae populations in different latitudes, including the population of S. goodbodyi in the beach of Manguinhos, showed variability in their rates probably due to the differences of several factors such as life history and environmental variability

Cephalopod populations: definition and dynamics

1996 ◽  
Vol 351 (1343) ◽  
pp. 985-1002 ◽  
Keyword(s):  
Environmental Variability ◽  
Marine Ecosystem ◽  
High Mobility ◽  
Marine Ecology ◽  
Trophic Levels ◽  
Commercial Fishing ◽  
Mortality Factors ◽  
High Turnover ◽  
Short Lifespan ◽  
Marine Habitats

The study of cephalopod populations currently lacks the means to define populations adequately and to resolve basic systematic confusions. Quantitative data are usually only available from indirect sources such as commercial fisheries and from estimates of consumption by higher predators. Despite these methodological difficulties it is clear that cephalopods comprise a major component of biomass globally, throughout all fully marine habitats. Life-cycle characteristics common to the coleoids - early and/or semelparous breeding, rapid growth, short lifespan, little overlap of generations, vulnerability to predation and environmental variables - result in wide inter-annual fluctuations in abundance. Most of the pelagic forms also undertake large- or meso-scale migrations which, coupled to shifting patterns of oceanographic variables, contribute to the unpredictability of distribution and density associated with many cephalopod species. Temporal and spatial patterns of breeding, seasonality, growth, recruitment and mortality are clearly evident in most of the better-studied species. But exceptions to pattern (e.g. variable growth rates, extended breeding, complex recruitment) also seem to be important intrinsic characteristics. Levels of genetic variation in cephalopods are relatively low, and their population dynamics appear to be influenced principally by phenotypic plasticity in response to environmental variability. In such universally short-lived species the maintenance of this diversity balances the risks of mortality factors combining at any one time to cause periodic local extinction. The extent and scale of the interactions between cephalopod populations and other trophic levels suggests that major ecological perturbations such as environmental shifts, or imposed effects such as commercial fishing, whether directed at cephalopods or other species, are likely to have an impact on their populations. As short-lived species with high turnover of generations, plastic growth and reproductive characteristics, high mobility and catholic predatory habits, they are always poised to respond to changed balances in their environment. Studies on cephalopod populations have expanded considerably in numbers and scope in the last 25 years, driven by increased interest in and recognition of their roles in the marine ecology, as well as their increasing value as globally exploited resources. Despite these recent advances, the information and concepts arising from their study is only slowly entering mainstream biological thought and becoming accommodated in broad-scale models of the marine ecosystem.

Population structure, growth and production of Laeonereis culveri (Nereididae: Polychaeta) in tidal flats of Río de la Plata estuary, Argentina

2006 ◽  
Vol 86 (2) ◽  
pp. 235-244 ◽  
Author(s):  
J.P. Martin ◽  
R. Bastida
Keyword(s):  
Growth Rate ◽  
Population Structure ◽  
Life Span ◽  
Secondary Production ◽  
Tidal Flats ◽  
Trophic Levels ◽  
Rio De La Plata ◽  
Estuarine Ecosystem ◽  
Río De La Plata ◽  
La Plata

A benthic survey was carried out from November 1998 to December 1999 in the tidal flats of Bahía Samborombón (Río de la Plata estuary, Argentina), in order to study the population structure, growth and secondary production of Laeonereis culveri. The samples were collected monthly in two intertidal areas with different environmental characteristics (San Clemente Creek and Punta Rasa). Growth was analysed using computer-based methods of length–frequency data (ELEFAN), and the secondary production was estimated by Crisp's and Hynes & Coleman's methods. Laeonereis culveri were recruited throughout the year, with two main peaks during spring and autumn. The autumn cohort showed growth rate (K) of 2 in San Clemente Creek and 1.8 in Punta Rasa. The seasonal oscillation of growth pointed out that worms grow very slowly during winter months. The life span of this cohort ranged from 15 to 17 months. The spring cohort showed higher growth rates in both sampled areas (K=3.3 in Punta Rasa and 3.1 in San Clemente Creek), whereas the growth oscillation showed similar values to those of the autumn cohort. The lowest growth rate was found in January and the life span was 9.5 months. The annual mean biomass in San Clemente Creek was 5.44 g m−2, with a mean production of 40.8 and 43.8 g m−2 y−1, according to the method used, and a production/biomass (P/B) ratio of 7.5 and 8 y−1 respectively. In Punta Rasa, the annual mean biomass (2.69 g m−2) and mean secondary production (19.44 and 23.61 g m−2 y−1, according to the method used) were lower than in San Clemente Creek, nevertheless the P/B ratio (7.2 and 8.7 y−1) was similar. The high secondary production and P/B ratio observed suggest that L. culveri transfer an important biomass to higher trophic levels, pointing out the very important role that this polychaete plays in the energy flux of this coastal estuarine ecosystem.

scholarly journals Robustness of life histories to environmental variability in complex versus simple life cycles

2021 ◽  
Author(s):  
Annie Jonsson
Keyword(s):  
Growth Rate ◽  
Life Histories ◽  
Environmental Variability ◽  
Life Cycles ◽  
Relative Advantage ◽  
Complex Life Cycle ◽  
Life Stages ◽  
Vital Rates ◽  
Habitat Separation ◽  
Simple Life

AbstractMost animal species have a complex life cycle (CLC) with metamorphosis. It is thus of interest to examine possible benefits of such life histories. The prevailing view is that CLC represents an adaptation for genetic decoupling of juvenile and adult traits, thereby allowing life stages to respond independently to different selective forces. Here I propose an additional potential advantage of CLCs that is, decreased variance in population growth rate due to habitat separation of life stages. Habitat separation of pre- and post-metamorphic stages means that the stages will experience different regimes of environmental variability. This is in contrast to species with simple life cycles (SLC) whose life stages often occupy one and the same habitat. The correlation in the fluctuations of the vital rates of life stages is therefore likely to be weaker in complex than in simple life cycles. By a theoretical framework using an analytical approach, I have (1) derived the relative advantage, in terms of long-run growth rate, of CLC over SLC phenotypes for a broad spectrum of life histories, and (2) explored which life histories that benefit most by a CLC, that is avoid correlation in vital rates between life stages. The direction and magnitude of gain depended on life history type and fluctuating vital rate. One implication of our study is that species with CLCs should, on average, be more robust to increased environmental variability caused by global warming than species with SLCs.

Evaluation of genomic sequence-based growth rate methods for synchronized Synechococcus cultures

2021 ◽  
Author(s):  
Julia Carroll ◽  
Nicolas Van Oostende ◽  
Bess B. Ward
Keyword(s):  
Cell Cycle ◽  
Growth Rate ◽  
Dna Replication ◽  
Growth Rates ◽  
Genomic Sequence ◽  
Niche Differentiation ◽  
Trophic Levels ◽  
Individual Species ◽  
Cell Counts

Standard methods for calculating microbial growth rates (μ) through the use of proxies, such as in situ fluorescence, cell cycle, or cell counts, are critical for determining the magnitude of the role bacteria play in marine carbon (C) and nitrogen (N) cycles. Taxon-specific growth rates in mixed assemblages would be useful for attributing biogeochemical processes to individual species and understanding niche differentiation among related clades, such as found in Synechococcus and Prochlorococcus . We tested three novel DNA sequencing-based methods (iRep, bPTR, and GRiD) for evaluating growth of light synchronized Synechococcus cultures under different light intensities and temperatures. In vivo fluorescence and cell cycle analysis were used to obtain standard estimates of growth rate for comparison with the sequence-based methods (SBM). None of the SBM values were correlated with growth rates calculated by standard techniques despite the fact that all three SBM were correlated with percentage of cells in S phase (DNA replication) over the diel cycle. Inaccuracy in determining the time of maximum DNA replication is unlikely to account entirely for the absence of relationship between SBM and growth rate, but the fact that most microbes in the surface ocean exhibit some degree of diel cyclicity is a caution for application of these methods. SBM correlate with DNA replication but cannot be interpreted quantitatively in terms of growth rate. Importance Small but abundant, cyanobacterial strains such as the photosynthetic Synechococcus spp. are essential because they contribute significantly to primary productivity in the ocean. These bacteria generate oxygen and provide biologically-available carbon, which is essential for organisms at higher trophic levels. The small size and diversity of natural microbial assemblages means that taxon-specific activities (e.g., growth rate) are difficult to obtain in the field. It has been suggested that sequence-based methods (SBM) may be able to solve this problem. We find, however, that SBM can detect DNA replication and are correlated with phases of the cell cycle but cannot be interpreted in terms of absolute growth rate for Synechococcus cultures growing under a day-night cycle, like that experienced in the ocean.

scholarly journals Declines in an abundant aquatic insect, the burrowing mayfly, across major North American waterways

2020 ◽  
Vol 117 (6) ◽  
pp. 2987-2992 ◽  
Author(s):  
Phillip M. Stepanian ◽  
Sally A. Entrekin ◽  
Charlotte E. Wainwright ◽  
Djordje Mirkovic ◽  
Jennifer L. Tank ◽  
...  
Keyword(s):  
Mississippi River ◽  
Animal Movement ◽  
Aquatic Insect ◽  
Terrestrial Ecosystems ◽  
Trophic Levels ◽  
Western Lake ◽  
Annual Biomass ◽  
Emergence Event ◽  
Western Lake Erie

Seasonal animal movement among disparate habitats is a fundamental mechanism by which energy, nutrients, and biomass are transported across ecotones. A dramatic example of such exchange is the annual emergence of mayfly swarms from freshwater benthic habitats, but their characterization at macroscales has remained impossible. We analyzed radar observations of mayfly emergence flights to quantify long-term changes in annual biomass transport along the Upper Mississippi River and Western Lake Erie Basin. A single emergence event can produce 87.9 billion mayflies, releasing 3,078.6 tons of biomass into the airspace over several hours, but in recent years, production across both waterways has declined by over 50%. As a primary prey source in aquatic and terrestrial ecosystems, these declines will impact higher trophic levels and environmental nutrient cycling.

scholarly journals PISCES-v2: an ocean biogeochemical model for carbon and ecosystem studies

2015 ◽  
Vol 8 (2) ◽  
pp. 1375-1509 ◽  
Author(s):  
O. Aumont ◽  
C. Ethé ◽  
A. Tagliabue ◽  
L. Bopp ◽  
M. Gehlen
Keyword(s):  
Growth Rate ◽  
Marine Ecosystem ◽  
Trophic Levels ◽  
Full Description ◽  
Biogeochemical Model ◽  
Ecosystem Studies ◽  
Ocean Biogeochemical Model ◽  
Iron Chemistry ◽  
Steady State Simulation

Abstract. PISCES-v2 is a biogeochemical model which simulates the lower trophic levels of marine ecosystem (phytoplankton, microzooplankton and mesozooplankton) and the biogeochemical cycles of carbon and of the main nutrients (P, N, Fe, and Si). The model is intended to be used for both regional and global configurations at high or low spatial resolutions as well as for short-term (seasonal, interannual) and long-term (climate change, paleoceanography) analyses. There are twenty-four prognostic variables (tracers) including two phytoplankton compartments (diatoms and nanophytoplankton), two zooplankton size-classes (microzooplankton and mesozooplankton) and a description of the carbonate chemistry. Formulations in PISCES-v2 are based on a mixed Monod–Quota formalism: on one hand, stoichiometry of C/N/P is fixed and growth rate of phytoplankton is limited by the external availability in N, P and Si. On the other hand, the iron and silicium quotas are variable and growth rate of phytoplankton is limited by the internal availability in Fe. Various parameterizations can be activated in PISCES-v2, setting for instance the complexity of iron chemistry or the description of particulate organic materials. So far, PISCES-v2 has been coupled to the NEMO and ROMS systems. A full description of PISCES-v2 and of its optional functionalities is provided here. The results of a quasi-steady state simulation are presented and evaluated against diverse observational and satellite-derived data. Finally, some of the new functionalities of PISCES-v2 are tested in a series of sensitivity experiments.

An efficient method for collecting large samples of live copepods free from detritus

2010 ◽  
Vol 61 (5) ◽  
pp. 621 ◽  
Author(s):  
Carl J. Svensson ◽  
Glenn A. Hyndes ◽  
Paul S. Lavery
Keyword(s):  
Fatty Acids ◽  
Food Web ◽  
Trophic Levels ◽  
Aquatic Systems ◽  
New Method ◽  
Aquatic Environments ◽  
Web Studies ◽  
Large Samples ◽  
Large Numbers ◽  
Harpacticoid Copepods

Meiofauna are often important in the transfer of organic material to higher trophic levels in aquatic environments. However, in food web analysis the group is frequently pooled or ignored owing to the difficulty in isolating individual components of the assemblage. In this study, we developed and tested a new method for extracting photopositive and detritus-free copepod samples from sediments, and compared this method to a previous technique (Couch 1989). In our initial trials, ∼400 copepods (all orders included) were collected in 15 min compared with 60 copepods using Couch’s method. In subsequent trials that focussed on specific orders of copepods, our method was at least 10 times more efficient than Couch’s method at collecting cyclopoid and harpacticoid copepods from sediments. The new method requires very little supervision and there is no requirement for a particular intensity of light. This method can increase the collection of large numbers of photopositive copepods in aquatic systems, and thereby facilitate the inclusion of this important component into future food web studies, particularly those using biomarkers such as stable isotopes or fatty acids.

Aspects of Estimating Zooplankton Production from Phytoplankton Production

1969 ◽  
Vol 26 (2) ◽  
pp. 199-220 ◽  
Author(s):  
C. D. McAllister
Keyword(s):  
Growth Rate ◽  
Primary Productivity ◽  
Secondary Production ◽  
Relative Effect ◽  
Plant Production ◽  
Phytoplankton Production ◽  
Continuous Grazing ◽  
Different Types ◽  
Phytoplankton Growth Rate ◽  
Zooplankton Production

Primary productivity and zooplankton data from Ocean Station P are used to compare estimates of phytoplankton and herbivore production calculated on the assumption of continuous grazing by the animals with estimates obtained on the assumption of three different types of nocturnal grazing. Effective plant production, that corrected for the effects of grazing on the size of the phytoplankton stock and hence on the magnitude of the plant respiratory loss, was less than the measured production and was least under the assumption of continuous grazing. The small differences in effective production resulting from the choice of different grazing schemes resulted in large differences in estimates of secondary production. The relative effect of assuming different grazing schemes on the estimate of secondary production varied markedly with zooplankton respiration and with the phytoplankton growth rate.

scholarly journals Response of nutrients, biofilm, and benthic insects to salmon carcass addition

2006 ◽  
Vol 63 (6) ◽  
pp. 1230-1241 ◽  
Author(s):  
Shannon M Claeson ◽  
Judith L Li ◽  
Jana E Compton ◽  
Peter A Bisson
Keyword(s):  
Leaf Litter ◽  
Litter Decomposition ◽  
Headwater Streams ◽  
Dry Mass ◽  
Trophic Levels ◽  
Leaf Litter Decomposition ◽  
Ammonium Concentration ◽  
Benthic Insects ◽  
Salmon Carcass ◽  
Density And Biomass

Salmon carcass addition to streams is expected to increase stream productivity at multiple trophic levels. This study examined stream nutrient (nitrogen, phosphorus, and carbon), epilithic biofilm (ash-free dry mass and chlorophyll a), leaf-litter decomposition, and macroinvertebrate (density and biomass) responses to carcass addition in three headwater streams of southwestern Washington State, USA. We used stable isotopes (δ13C and δ15N) to trace incorporation of salmon-derived (SD) nutrients into stream food webs. SD nutrients were assimilated by biofilm, benthic insects (Perlidae and Limnephilidae spp.), and age-1 steelhead (Oncorhynchus mykiss gairdneri). SD nutrients peaked ~2 weeks after carcass addition for insects and fish feeding on carcasses, but indirect uptake of SD nutrients by biofilm and insects was delayed by ~2 months. A strong stable isotope signal did not always correspond with measurable biological change. At reaches 10–50 m downstream from carcasses, ammonium concentration, leaf-litter decomposition, and benthic insect density all increased relative to upstream control sites. The strongest responses and greatest SD-nutrient uptake were observed 10 m from decomposing carcasses, with effects generally decreasing to undetectable levels 250 m downstream. Carcass addition to headwater streams can have a transient effect on primary and secondary trophic levels, but responses may be limited to specific taxa near carcass locations.

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