Temporal succession of a macrofaunal community associated with kelp fragment accumulations in an in situ experiment

2020 ◽  
Vol 656 ◽  
pp. 109-121 ◽  
Author(s):  
F de Bettignies ◽  
P Dauby ◽  
G Lepoint ◽  
P Riera ◽  
E Bocher ◽  
...  
Keyword(s):  
Food Web ◽  
Decay Process ◽  
Kelp Forests ◽  
Community Succession ◽  
Storm Events ◽  
Laminaria Hyperborea ◽  
In Situ Experiment ◽  
Sandy Bottom ◽  
Species Dominance ◽  
Macrofaunal Community

A large part of the production of Laminaria hyperborea kelp forests is not directly consumed by grazers, but is exported during storm events or natural annual blade erosion. Drifting kelp fragments are transported and can accumulate temporarily over subtidal benthic habitats. The decay process is particularly slow (>6 mo for complete decay during spring-summer) and L. hyperborea fragments are able to maintain their primary production function for several months. If they accumulate in low subtidal habitats, fragments can have a long residence time, thus modifying habitat structure. Based on a 6 mo cage experiment, we investigated macrofaunal colonization and community succession within accumulations of L. hyperborea fragments on a low subtidal (-10 m) sandy bottom ecosystem. Stable isotope (δ13C and δ15N) measurements were carried out to describe the structure and development of the trophic food web and the role of detritus as a food source. Kelp tissues were rapidly and abundantly colonized by macrofauna, and a classical ecological succession occurred, with changes in species dominance and increase in diversity during decay. The food web was based on 2 main sources: particulate organic matter from the water column and decaying kelp tissues. Kelp contributed significantly to the diet of numerous species that are commonly consumed by local predators (fish, shrimp). Following community succession, diets diversified and the food web became more complex during the decay process. Our results indicate that drift kelp accumulations structure their associated communities and food web during the whole decay process.

scholarly journals The other ocean acidification problem: CO 2 as a resource among competitors for ecosystem dominance

2013 ◽  
Vol 368 (1627) ◽  
pp. 20120442 ◽  
Author(s):  
Sean D. Connell ◽  
Kristy J. Kroeker ◽  
Katharina E. Fabricius ◽  
David I. Kline ◽  
Bayden D. Russell
Keyword(s):  
Coral Reefs ◽  
Ocean Acidification ◽  
Atmospheric Carbon Dioxide ◽  
Environmental Changes ◽  
Kelp Forests ◽  
Direct Effects ◽  
Species Dominance ◽  
Tropical Conditions ◽  
Near Future

Predictions concerning the consequences of the oceanic uptake of increasing atmospheric carbon dioxide (CO 2 ) have been primarily occupied with the effects of ocean acidification on calcifying organisms, particularly those critical to the formation of habitats (e.g. coral reefs) or their maintenance (e.g. grazing echinoderms). This focus overlooks direct and indirect effects of CO 2 on non-calcareous taxa that play critical roles in ecosystem shifts (e.g. competitors). We present the model that future atmospheric [CO 2 ] may act as a resource for mat-forming algae, a diverse and widespread group known to reduce the resilience of kelp forests and coral reefs. We test this hypothesis by combining laboratory and field CO 2 experiments and data from ‘natural’ volcanic CO 2 vents. We show that mats have enhanced productivity in experiments and more expansive covers in situ under projected near-future CO 2 conditions both in temperate and tropical conditions. The benefits of CO 2 are likely to vary among species of producers, potentially leading to shifts in species dominance in a high CO 2 world. We explore how ocean acidification combines with other environmental changes across a number of scales, and raise awareness of CO 2 as a resource whose change in availability could have wide-ranging community consequences beyond its direct effects.

Spatiotemporal variation in the structure of reef fish and macroalgal assemblages in a north-east Atlantic kelp forest ecosystem: implications for the management of temperate rocky reefs

2018 ◽  
Vol 69 (4) ◽  
pp. 525 ◽  
Author(s):  
Pablo Pita ◽  
Diana Fernández-Márquez ◽  
Juan Freire
Keyword(s):  
Reef Fish ◽  
Fish Assemblages ◽  
Kelp Forest ◽  
Habitat Destruction ◽  
Kelp Forests ◽  
Rocky Reef ◽  
Laminaria Hyperborea ◽  
East Atlantic ◽  
North East ◽  
Rocky Reefs

Temperate rocky reefs and kelp forest ecosystems have been severely affected by overfishing, pollution and habitat destruction, and climate change is a major driver of kelp decline in many regions. Although necessary for management, ecological interactions between kelp and fish remain largely unknown in the north-east Atlantic. In the present study, underwater visual censuses (UVC) and univariate and multivariate multiple regression models were used to analyse the spatiotemporal variations in the abundance and habitat use of the rocky reef fish and macroalgae assemblages of Galicia (north-west Spain). The underwater seascape was dominated by large rocks and kelp forests of Laminaria hyperborea, L. ochroleuca and Saccorhiza polyschides. Fish assemblages were ruled by gadids, labrids and sparids. The most frequent fish species were Labrus bergylta (counted in 90% of UVC) and Pollachius pollachius (in 100% of UVC), whereas the most abundant were Boops boops (mean±s.d., 556.4±39.7 individuals ha–1) and L. bergylta (432.10±440.05 individuals ha–1). Fish and macroalgal assemblages showed different spatial preferences and responded strongly to seasonality, wave exposure and depth. To a lesser degree, fish and macroalgal assemblages showed preferences for habitat structure. Moreover, because the findings of the present study indicate that L. bergylta is a good indicator species of the health of rocky reef and kelp forests ecosystems, monitoring of this fish can be helpful for management and conservation actions.

scholarly journals Importance of wave and current exposure to fauna communities in Laminaria hyperborea kelp forests

2014 ◽  
Vol 502 ◽  
pp. 295-301 ◽  
Author(s):  
KM Norderhaug ◽  
H Christie ◽  
E Rinde ◽  
H Gundersen ◽  
T Bekkby
Keyword(s):  
Kelp Forests ◽  
Laminaria Hyperborea ◽  
Current Exposure

scholarly journals Variation in Population Structure and Standing Stocks of Kelp Along Multiple Environmental Gradients and Implications for Ecosystem Services

2021 ◽  
Vol 8 ◽  
Author(s):  
Hege Gundersen ◽  
Eli Rinde ◽  
Trine Bekkby ◽  
Kasper Hancke ◽  
Janne K. Gitmark ◽  
...  
Keyword(s):  
Ecosystem Services ◽  
Environmental Gradients ◽  
Standing Stock ◽  
Morphological Characteristics ◽  
Wave Exposure ◽  
Kelp Forests ◽  
Laminaria Hyperborea ◽  
Plant Weight ◽  
Carbon Sequestration Potential ◽  
Sequestration Potential

There is an increasing focus on ecosystem services provided by macroalgae worldwide, many which depend on its structural and morphological characteristics. Here we investigated how characteristics of canopy kelp plants of Laminaria hyperborea varies along the Norwegian part of the NE Atlantic. Ten characteristics related to size, allometry, density, biomass and epiphytes were analyzed along wide gradients of depth, wave exposure and latitude. The analyses were performed on a compiled dataset of 630 scuba samples from different research and monitoring projects along the Norwegian coast (58-71°N). The largest kelps, highest biomass, and highest biomass of epiphytic algae was found in Mid-Norway (63-65°N). While most size-related kelp characteristics were reduced with water depth, they were enlarged with wave exposure. The developed statistical models can be used to calculate site-specific values (and their variation) of the different characteristics at any location based on latitude, depth and wave exposure. These can further be used to map kelp derived ecosystem services. We predicted region-specific estimates of total plant weight, kelp density and kelp biomass. Moreover, the models were applied to estimate living biomass (56 million tonnes fresh weight), carbon standing stock (2.6 million tonnes carbon or 9.5 million tonnes CO2), and carbon sequestration potential (0.46 million tonnes per year) for the Norwegian kelp forests, that were estimated to cover about 5 355 km2. The site- and region-specific estimates are relevant to kelp forest management and for blue carbon accountings.

scholarly journals Climate-driven shifts in species' distributions may exacerbate the impacts of storm disturbances on North-east Atlantic kelp forests

2016 ◽  
Vol 67 (1) ◽  
pp. 65 ◽  
Author(s):  
Dan A. Smale ◽  
Thomas Vance
Keyword(s):  
Kelp Forest ◽  
Species Distributions ◽  
Wave Action ◽  
Saccharina Latissima ◽  
Kelp Forests ◽  
Storm Damage ◽  
Laminaria Hyperborea ◽  
East Atlantic ◽  
North East ◽  
The North

Physical disturbance through wave action is a major determinant of kelp forest structure. The North-east Atlantic storm season of 2013–14 was unusually severe; the south coast of the UK was subjected to 6 of the 12 most intense storms recorded in the past 5 years. Inshore significant wave heights and periods exceeded 7m and 13s with two storms classified as ‘1-in-30 year’ events. We examined the impacts of the storm season on kelp canopies at three study sites. Monospecific canopies comprising Laminaria hyperborea were unaffected by storm disturbance. However, at one study site a mixed canopy comprising Laminaria ochroleuca, Saccharina latissima and L. hyperborea was significantly altered by the storms, due to decreased abundances of the former two species. Quantification of freshly severed stipes suggested that the ‘warm water’ kelp L. ochroleuca was more susceptible to storm damage than L. hyperborea. Overall, kelp canopies were highly resistant to storm disturbance because of the low vulnerability of L. hyperborea to intense wave action. However, if climate-driven shifts in kelp species distributions result in more mixed canopies, as predicted, then resistance to storm disturbance may be eroded.

BIVALVE CONTRIBUTION TO SHALLOW SANDY BOTTOM FOOD WEB OFF MAR DEL PLATA (ARGENTINA): INFERENCE FROM STOMACH CONTENTS AND STABLE ISOTOPE ANALYSIS

2006 ◽  
Vol 25 (1) ◽  
pp. 51-54 ◽  
Author(s):  
PABLO E. PENCHASZADEH ◽  
FLORENCIA ARRIGHETTI ◽  
MAXIMILIANO CLEDÓN ◽  
JUAN PABLO LIVORE ◽  
FLORENCIA BOTTO ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Food Web ◽  
Stable Isotope Analysis ◽  
Isotope Analysis ◽  
Stomach Contents ◽  
Sandy Bottom

scholarly journals A food web including parasites for kelp forests of the Santa Barbara Channel, California

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Dana N. Morton ◽  
Cristiana Y. Antonino ◽  
Farallon J. Broughton ◽  
Lauren N. Dykman ◽  
Armand M. Kuris ◽  
...  
Keyword(s):  
Food Web ◽  
Kelp Forest ◽  
Kelp Forests ◽  
Life Stages ◽  
Santa Barbara Channel ◽  
Santa Barbara ◽  
Free Living ◽  
Predator Prey ◽  
Research Questions ◽  
System Nodes

AbstractWe built a high-resolution topological food web for the kelp forests of the Santa Barbara Channel, California, USA that includes parasites and significantly improves resolution compared to previous webs. The 1,098 nodes and 21,956 links in the web describe an economically, socially, and ecologically vital system. Nodes are broken into life-stages, with 549 free-living life-stages (492 species from 21 Phyla) and 549 parasitic life-stages (450 species from 10 Phyla). Links represent three kinds of trophic interactions, with 9,352 predator-prey links, 2,733 parasite-host links and 9,871 predator-parasite links. All decisions for including nodes and links are documented, and extensive metadata in the node list allows users to filter the node list to suit their research questions. The kelp-forest food web is more species-rich than any other published food web with parasites, and it has the largest proportion of parasites. Our food web may be used to predict how kelp forests may respond to change, will advance our understanding of parasites in ecosystems, and fosters development of theory that incorporates large networks.

scholarly journals Biogeochemical fluxes and fate of diazotroph derived nitrogen in the food web after a phosphate enrichment: Modeling of the VAHINE mesocosms experiment

2016 ◽  
Author(s):  
A. Gimenez ◽  
M. Baklouti ◽  
S. Bonnet ◽  
T. Moutin
Keyword(s):  
Primary Production ◽  
Food Web ◽  
N2 Fixation ◽  
New Caledonia ◽  
Mechanistic Model ◽  
In Situ Experiment ◽  
Planktonic Food ◽  
Biogeochemical Fluxes

Abstract. The VAHINE mesocosm experiment in the oligotrophic waters of the Noumea lagoon (New Caledonia) aimed to assess the role of the nitrogen input through N2 fixation on carbon production and export, and to study the fate of diazotroph-derived nitrogen (DDN) throughout the planktonic food web. A 1D-vertical biogeochemical mechanistic model was used in addition to the in situ experiment to complement our comprehension of the dynamics of the planktonic ecosystem and the main biogeochemical carbon (C), nitrogen (N), phosphate (P) fluxes. The mesocosms were intentionally enriched with 0.8 μmol.L−1 of P to trigger the development of diazotrophs and amplify biogeochemical fluxes. Two simulations were run, one with and the other without the phosphate enrichment. In the P-enriched simulation, N2 fixation, primary production and C export increased by 201, 208 and 87 %, respectively, consistent with the observed trends observed in the mesocosms (+ 124 %, + 141 %, + 261 % for N2 fixation, PP and C export, respectively). The increase in primary and export productions became significant 10 days after the DIP enrichment, indicating that i) several days were necessary to obtain a significant response at the population scale, and ii) classical methods (short-term microscosms experiments) used to quantify nutrient limitations of primary production may not be relevant. The model allowed to follow the fate of fixed N2 by providing over time the proportion of DDN in each compartment (mineral and organic) of the model. At the end of the simulation (25 days), 43 % of the DDN was found in the non-diazotroph organisms, 33 % in diazotrophs, 16 % in the dissolved organic nitrogen pool, 3 % in the particulate detrital organic pool and 5 % in traps, indicating that N2 fixation efficiently benefitted to non-diazotrophic organisms and contributed to C export.

scholarly journals Biogeochemical fluxes and fate of diazotroph-derived nitrogen in the food web after a phosphate enrichment: modeling of the VAHINE mesocosms experiment

2016 ◽  
Vol 13 (17) ◽  
pp. 5103-5120 ◽  
Author(s):  
Audrey Gimenez ◽  
Melika Baklouti ◽  
Sophie Bonnet ◽  
Thierry Moutin
Keyword(s):  
Primary Production ◽  
Food Web ◽  
N2 Fixation ◽  
New Caledonia ◽  
Mechanistic Model ◽  
In Situ Experiment ◽  
Planktonic Food ◽  
Biogeochemical Fluxes

Abstract. The VAHINE mesocosm experiment in the oligotrophic waters of the Nouméa lagoon (New Caledonia), where high N2 fixation rates and abundant diazotroph organisms were observed, aimed to assess the role of the nitrogen input through N2 fixation in carbon production and export and to study the fate of diazotroph-derived nitrogen (DDN) throughout the planktonic food web. A 1-D vertical biogeochemical mechanistic model was used in addition to the in situ experiment to enrich our understanding of the dynamics of the planktonic ecosystem and the main biogeochemical carbon (C), nitrogen (N) and phosphate (P) fluxes. The mesocosms were intentionally enriched with  ∼  0.8 µmol L−1 of inorganic P to trigger the development of diazotrophs and amplify biogeochemical fluxes. Two simulations were run, one with and the other without the phosphate enrichment. In the P-enriched simulation, N2 fixation, primary production (PP) and C export increased by 201, 208 and 87 %, respectively, consistent with the trends observed in the mesocosms (+124, +141 and +261 % for N2 fixation, PP and C export, respectively). In total, 5–10 days were necessary to obtain an increase in primary and export productions after the dissolved inorganic phosphate (DIP) enrichment, thereby suggesting that classical methods (short-term microcosms experiments) used to quantify nutrient limitations of primary production may not be relevant. The model enabled us to monitor the fate of fixed N2 by providing the proportion of DDN in each compartment (inorganic and organic) of the model over time. At the end of the simulation (25 days), 43 % of the DDN was found in the non-diazotroph organisms, 33 % in diazotrophs, 16 % in the dissolved organic nitrogen pool, 3 % in the particulate detrital organic pool and 5 % in traps, indicating that N2 fixation was of benefit to non-diazotrophic organisms and contributed to C export.

scholarly journals Kelp-Associated Microbes Facilitate Spatial Subsidy in a Detrital-Based Food Web in a Shoreline Ecosystem

2021 ◽  
Vol 8 ◽  
Author(s):  
Charu Lata Singh ◽  
Megan J. Huggett ◽  
Paul S. Lavery ◽  
Christin Säwström ◽  
Glenn A. Hyndes
Keyword(s):  
Food Web ◽  
Reproductive Output ◽  
Bacterial Abundance ◽  
C:N Ratio ◽  
Reproductive Development ◽  
Nutrient Content ◽  
Kelp Forests ◽  
Spatial Subsidy ◽  
Associated Bacteria ◽  
Marine Systems

Microbes are ubiquitous but our knowledge of their effects on consumers is limited in benthic marine systems. Shorelines often form hotspots of microbial and detritivore activity due to the large amounts of detrital macrophytes that are exported from other coastal ecosystems, such as kelp forests, and accumulate in these systems. Shoreline ecosystems therefore provide a useful model system to examine microbial-detritivore interactions. We experimentally test whether bacteria in the biofilm of kelp provide a bottom-up influence on growth and reproductive output of detritivores in shorelines where detrital kelp accumulates, by manipulating the bacterial abundances on kelp (Ecklonia radiata). The growth rates for both male and female amphipods (Allorchestes compressa) were greater in treatments containing bacteria than those in which bacteria were reduced through antibiotic treatment, and this effect was greater for males offered aged kelp. The proportions of ovigerous females were greater when reared on kelp with intact bacteria, indicating a more rapid reproductive development in the presence of more bacteria. Bacterial abundance had little to no influence on nutrient content and palatability of kelp, based on tissue toughness, nitrogen and carbon content and C:N ratio. Thus, the most likely pathway for a microbial effect on detritivores was through feeding on kelp-associated bacteria. Regardless of the pathway, kelp-associated microbes have a strong influence on the fitness of a highly abundant detritivore that feeds preferentially on E. radiata in shoreline systems, and therefore form a hidden trophic step in this “brown” food web and a hotspot of secondary production.

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