scholarly journals Trophodynamics of nekton assemblages and relationships with estuarine habitat structure across a subtropical estuary

2018 ◽  
Author(s):  
Shannon D Whaley ◽  
James J Burd ◽  
Craig W. Harmak ◽  
Colin P Shea
Keyword(s):  
Gulf Of Mexico ◽  
Food Web ◽  
Trophic Levels ◽  
Spatial Gradient ◽  
Seagrass Beds ◽  
Charlotte Harbor ◽  
Wading Birds ◽  
Benthic Production ◽  
Important Time ◽  
And Function

Understanding trophodynamics of estuarine and marine ecosystems is important in developing food-web models prevalent in ecosystem-based approaches to fisheries management, as well as assessing ecosystem condition and function. Few studies have examined seasonal and spatial trophodynamics of nekton assemblages in shallow subtropical waters on estuary-wide spatial extent. We used fisheries-independent monitoring data to examine the spatial distribution and seasonal trophodynamics of nekton assemblages in shallow waters (≤ 1.5m) of Charlotte Harbor, Florida, USA, as well as the lower Peace and Myakka Rivers. Overall nekton densities were generally high in spring (April - May), especially in the lower rivers, and declined through the summer (June – October), and fall (November – December), with small increases in mean nekton densities in winter (January – March). We found that species composition as well as trophic structure of nekton assemblages changed along a broad spatial gradient from the lower portions of the Peace and Myakka Rivers to lower Charlotte Harbor near the passes to the Gulf of Mexico. Nekton assemblages dominated by planktonic-feeding species were located in lower Peace and Myakka Rivers and extended into upper Charlotte Harbor in apparent response to seasonal fluctuations in freshwater inflow. In contrast, most of the nekton assemblages within Charlotte Harbor proper were dominated by nekton species feeding within the benthos (those feeding on benthic infauna, epifauna, seagrass, and/or detritus) throughout the year. The proportion of benthic feeders was positively correlated with landscape metrics describing the area of continuous seagrass beds mapped from aerial photography, and negatively correlated with distance to the nearest pass to the Gulf of Mexico. These relationships were consistent throughout all four seasons of the year. The proportion of benthic feeders varied seasonally, and was relatively high in the fall and winter compared with the spring and summer. The predominance of benthic feeding species during fall and winter when overall nekton densities were low, suggests that benthic production is an important in supporting populations of forage fishes for higher trophic levels, such as piscivorous fishes and wading birds during this time of year. This is an important time for overwintering wading birds, as well as several economically-important fishery species who are recruiting into shallow water areas of Charlotte Harbor. Planktonic production is often the focus of food-web models with benthic production sometimes not included. We found both planktonic and benthic production to be important in Charlotte Harbor. Therefore, both sources of production need to be included in food-web models for Charlotte Harbor, as well as similar subtropical estuaries with relatively large areas of seagrass beds.

scholarly journals Trophodynamics of nekton assemblages and relationships with estuarine habitat structure across a subtropical estuary

2018 ◽  
Author(s):  
Shannon D Whaley ◽  
James J Burd ◽  
Craig W. Harmak ◽  
Colin P Shea
Keyword(s):  
Gulf Of Mexico ◽  
Food Web ◽  
Trophic Levels ◽  
Spatial Gradient ◽  
Seagrass Beds ◽  
Charlotte Harbor ◽  
Wading Birds ◽  
Benthic Production ◽  
Important Time ◽  
And Function

Understanding trophodynamics of estuarine and marine ecosystems is important in developing food-web models prevalent in ecosystem-based approaches to fisheries management, as well as assessing ecosystem condition and function. Few studies have examined seasonal and spatial trophodynamics of nekton assemblages in shallow subtropical waters on estuary-wide spatial extent. We used fisheries-independent monitoring data to examine the spatial distribution and seasonal trophodynamics of nekton assemblages in shallow waters (≤ 1.5m) of Charlotte Harbor, Florida, USA, as well as the lower Peace and Myakka Rivers. Overall nekton densities were generally high in spring (April - May), especially in the lower rivers, and declined through the summer (June – October), and fall (November – December), with small increases in mean nekton densities in winter (January – March). We found that species composition as well as trophic structure of nekton assemblages changed along a broad spatial gradient from the lower portions of the Peace and Myakka Rivers to lower Charlotte Harbor near the passes to the Gulf of Mexico. Nekton assemblages dominated by planktonic-feeding species were located in lower Peace and Myakka Rivers and extended into upper Charlotte Harbor in apparent response to seasonal fluctuations in freshwater inflow. In contrast, most of the nekton assemblages within Charlotte Harbor proper were dominated by nekton species feeding within the benthos (those feeding on benthic infauna, epifauna, seagrass, and/or detritus) throughout the year. The proportion of benthic feeders was positively correlated with landscape metrics describing the area of continuous seagrass beds mapped from aerial photography, and negatively correlated with distance to the nearest pass to the Gulf of Mexico. These relationships were consistent throughout all four seasons of the year. The proportion of benthic feeders varied seasonally, and was relatively high in the fall and winter compared with the spring and summer. The predominance of benthic feeding species during fall and winter when overall nekton densities were low, suggests that benthic production is an important in supporting populations of forage fishes for higher trophic levels, such as piscivorous fishes and wading birds during this time of year. This is an important time for overwintering wading birds, as well as several economically-important fishery species who are recruiting into shallow water areas of Charlotte Harbor. Planktonic production is often the focus of food-web models with benthic production sometimes not included. We found both planktonic and benthic production to be important in Charlotte Harbor. Therefore, both sources of production need to be included in food-web models for Charlotte Harbor, as well as similar subtropical estuaries with relatively large areas of seagrass beds.

scholarly journals The rise of the three-spined stickleback – eco-evolutionary consequences of a mesopredator release

2020 ◽  
Author(s):  
Britas Klemens Eriksson ◽  
Casey Yanos ◽  
Sarah Bourlat ◽  
Serena Donadi ◽  
Michael C. Fontaine ◽  
...  
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Stomach Content ◽  
Ecological Effects ◽  
Trophic Levels ◽  
Predatory Fish ◽  
Series Data ◽  
Food Web Structure ◽  
Benthic Production ◽  
Invertebrate Herbivores

AbstractDeclines of large predatory fish due to overexploitation are restructuring food webs across the globe. It is now becoming evident that restoring these altered food webs requires addressing not only ecological processes, but evolutionary ones as well, because human-induced rapid evolution may in turn affect ecological dynamics. In the central Baltic Sea, abundances of the mesopredatory fish, the three-spined stickleback (Gasterosteus aculeatus), have increased dramatically during the past decades. Time-series data covering 22 years show that this increase coincides with a decline in the number of juvenile perch (Perca fluviatilis), the most abundant predator of stickleback along the coast. We studied the interaction between evolutionary and ecological effects of this mesopredator take-over, by surveying the armour plate morphology of stickleback and the structure of the associated food web. First, we investigated the distribution of different stickleback phenotypes depending on predator abundances and benthic production; and described the stomach content of the stickleback phenotypes using metabarcoding. Second, we explored differences in the relation between different trophic levels and benthic production, between bays where the relative abundance of fish was dominated by stickleback or not; and compared this to previous cage-experiments to support causality of detected correlations. We found two distinct lateral armour plate phenotypes of stickleback, incompletely and completely plated. The proportion of incompletely plated individuals increased with increasing benthic production and decreasing abundances of adult perch. Stomach content analyses showed that the completely plated individuals had a stronger preference for invertebrate herbivores (amphipods) than the incompletely plated ones. In addition, predator dominance interacted with ecosystem production to determine food web structure and the propagation of a trophic cascade: with increasing production, biomass accumulated on the first (macroalgae) and third (stickleback) trophic levels in stickleback-dominated bays, but on the second trophic level (invertebrate herbivores) in perch-dominated bays. Since armour plates are defence structures favoured by natural selection in the presence of fish predators, the phenotype distribution suggest that a novel low-predation regime favours sticklebacks with less armour. Our results indicate that an interaction between evolutionary and ecological effects of the stickleback take-over has the potential to affect food web dynamics.

scholarly journals Perspectives on marine zooplankton lipids

2007 ◽  
Vol 64 (11) ◽  
pp. 1628-1639 ◽  
Author(s):  
G Kattner ◽  
W Hagen ◽  
R F Lee ◽  
R Campbell ◽  
D Deibel ◽  
...  
Keyword(s):  
Food Web ◽  
Trophic Levels ◽  
Future Research ◽  
Ocean Climate ◽  
Marine Food Web ◽  
Storage Lipids ◽  
Marine Zooplankton ◽  
Lipid Dynamics ◽  
And Function

We developed new perspectives to identify important questions and to propose approaches for future research on marine food web lipids. They were related to (i) structure and function of lipids, (ii) lipid changes during critical life phases, (iii) trophic marker lipids, and (iv) potential impact of climate change. The first addresses the role of lipids in membranes, storage lipids, and buoyancy with the following key question: How are the properties of membranes and deposits affected by the various types of lipids? The second deals with the importance of various types of lipids during reproduction, development, and resting phases and addresses the role of the different storage lipids during growth and dormancy. The third relates to trophic marker lipids, which are an important tool to follow lipid and energy transfer through the food web. The central question is how can fatty acids be used to identify and quantify food web relationships? With the fourth, hypotheses are presented on effects of global warming, which may result in the reduction or change in abundance of large, lipid-rich copepods in polar oceans, thereby strongly affecting higher trophic levels. The key question is how will lipid dynamics respond to changes in ocean climate at high latitudes?

Ultraviolet-B Radiation Effects on the Structure and Function of Lower Trophic Levels of the Marine Planktonic Food Web

2006 ◽  
Vol 82 (4) ◽  
pp. 887 ◽  
Author(s):  
Gustavo A. Ferreyra ◽  
Behzad Mostajir ◽  
Irene R. Schloss ◽  
Khaled Chatila ◽  
Martha E. Ferrario ◽  
...  
Keyword(s):  
Food Web ◽  
Radiation Effects ◽  
Structure And Function ◽  
Ultraviolet B ◽  
Trophic Levels ◽  
Ultraviolet B Radiation ◽  
Planktonic Food ◽  
And Function

scholarly journals Antibiotics as chemical warfare across multiple taxonomic domains and trophic levels in brown food webs

2019 ◽  
Vol 286 (1911) ◽  
pp. 20191536 ◽  
Author(s):  
Jane M. Lucas ◽  
Evan Gora ◽  
Annika Salzberg ◽  
Michael Kaspari
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Antibiotic Production ◽  
Anthropogenic Activities ◽  
Microbial Community Composition ◽  
Trophic Levels ◽  
Invertebrate Composition ◽  
Antibiotic Compounds ◽  
Bacteria And Fungi ◽  
And Function

Bacteria and fungi secrete antibiotics to suppress and kill other microbes, but can these compounds be agents of competition against macroorganisms? We explore how one competitive tactic, antibiotic production, can structure the composition and function of brown food webs. This aspect of warfare between microbes and invertebrates is particularly important today as antibiotics are introduced into ecosystems via anthropogenic activities, but the ecological implications of these introductions are largely unknown. We hypothesized that antimicrobial compounds act as agents of competition against invertebrate and microbial competitors. Using field-like mesocosms, we tested how antifungal and antibacterial compounds influence microbes, invertebrates, and decomposition in the brown food web. Both antibiotics changed prokaryotic microbial community composition, but only the antibacterial changed invertebrate composition. Antibacterials reduced the abundance of invertebrate detritivores by 34%. However, the addition of antimicrobials did not ramify up the food web as predator abundances were unaffected. Decomposition rates did not change. To test the mechanisms of antibiotic effects, we provided antibiotic-laden water to individual invertebrate detritivores in separate microcosm experiments. We found that the antibiotic compounds can directly harm invertebrate taxa, probably through a disruption of endosymbionts. Combined, our results show that antibiotic compounds could be an effective weapon for microbes to compete against both microbial and invertebrate competitors. In the context of human introductions, the detrimental effects of antibiotics on invertebrate communities indicates that the scope of this anthropogenic disturbance is much greater than previously expected.

Diel Variability and Influence of Artificial Light on Fish and Macroinvertebrate Communities in Gulf of Mexico Seagrass Beds

2020 ◽  
Author(s):  
Charles W. Martin ◽  
Laura K. Reynolds ◽  
Whitney A. Scheffel ◽  
Samantha Tiffany ◽  
Sara Kopetman
Keyword(s):  
Gulf Of Mexico ◽  
Artificial Light ◽  
Seagrass Beds ◽  
Macroinvertebrate Communities ◽  
Diel Variability

Dominant parasitoid species diminishes food web structural complexity and function

2021 ◽  
Author(s):  
Beatriz Mariana Pedroso ◽  
Tiago Morales-Silva ◽  
Lucas Del Bianco Faria
Keyword(s):  
Food Web ◽  
Structural Complexity ◽  
Parasitoid Species ◽  
And Function

scholarly journals Tree Diversity Reduces Fungal Endophyte Richness and Diversity in a Large-Scale Temperate Forest Experiment

Diversity ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 234 ◽  
Author(s):  
Eric A. Griffin ◽  
Joshua G. Harrison ◽  
Melissa K. McCormick ◽  
Karin T. Burghardt ◽  
John D. Parker
Keyword(s):  
Phylogenetic Diversity ◽  
Large Scale ◽  
High Throughput Sequencing ◽  
Spatial Scales ◽  
Fungal Endophytes ◽  
Fungal Endophyte ◽  
Tree Diversity ◽  
Trophic Levels ◽  
Community Diversity ◽  
And Function

Although decades of research have typically demonstrated a positive correlation between biodiversity of primary producers and associated trophic levels, the ecological drivers of this association are poorly understood. Recent evidence suggests that the plant microbiome, or the fungi and bacteria found on and inside plant hosts, may be cryptic yet important drivers of important processes, including primary production and trophic interactions. Here, using high-throughput sequencing, we characterized foliar fungal community diversity, composition, and function from 15 broadleaved tree species (N = 545) in a recently established, large-scale temperate tree diversity experiment using over 17,000 seedlings. Specifically, we tested whether increases in tree richness and phylogenetic diversity would increase fungal endophyte diversity (the “Diversity Begets Diversity” hypothesis), as well as alter community composition (the “Tree Diversity–Endophyte Community” hypothesis) and function (the “Tree Diversity–Endophyte Function” hypothesis) at different spatial scales. We demonstrated that increasing tree richness and phylogenetic diversity decreased fungal species and functional guild richness and diversity, including pathogens, saprotrophs, and parasites, within the first three years of a forest diversity experiment. These patterns were consistent at the neighborhood and tree plot scale. Our results suggest that fungal endophytes, unlike other trophic levels (e.g., herbivores as well as epiphytic bacteria), respond negatively to increasing plant diversity.

Functional diversity alters the effects of a pulse perturbation on the dynamics of tritrophic food webs

2021 ◽  
Author(s):  
Ruben Ceulemans ◽  
Laurie Anne Myriam Wojcik ◽  
Ursula Gaedke
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Functional Diversity ◽  
Feedback Loop ◽  
Environmental Changes ◽  
Biodiversity Loss ◽  
Trophic Levels ◽  
Nutrient Pulse ◽  
Trade Offs ◽  
Food Web Model

Biodiversity decline causes a loss of functional diversity, which threatens ecosystems through a dangerous feedback loop: this loss may hamper ecosystems' ability to buffer environmental changes, leading to further biodiversity losses. In this context, the increasing frequency of climate and human-induced excessive loading of nutrients causes major problems in aquatic systems. Previous studies investigating how functional diversity influences the response of food webs to disturbances have mainly considered systems with at most two functionally diverse trophic levels. Here, we investigate the effects of a nutrient pulse on the resistance, resilience and elasticity of a tritrophic---and thus more realistic---plankton food web model depending on its functional diversity. We compare a non-adaptive food chain with no diversity to a highly diverse food web with three adaptive trophic levels. The species fitness differences are balanced through trade-offs between defense/growth rate for prey and selectivity/half-saturation constant for predators. We showed that the resistance, resilience and elasticity of tritrophic food webs decreased with larger perturbation sizes and depended on the state of the system when the perturbation occured. Importantly, we found that a more diverse food web was generally more resistant, resilient, and elastic. Particularly, functional diversity dampened the probability of a regime shift towards a non-desirable alternative state. In addition, despite the complex influence of the shape and type of the dynamical attractors, the basal-intermediate interaction determined the robustness against a nutrient pulse. This relationship was strongly influenced by the diversity present and the third trophic level. Overall, using a food web model of realistic complexity, this study confirms the destructive potential of the positive feedback loop between biodiversity loss and robustness, by uncovering mechanisms leading to a decrease in resistance, resilience and elasticity as functional diversity declines.

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