The Response of Experimental Rocky Shore Communities to Nutrient Additions

Bokn, Tor; Duarte, Carlos M.; Pedersen, Morten Foldager; Marbà, Núria; Moy, Frithjof E.; Barrón, Cristina; Bjerkeng, Birger; Borum, Jens; Christie, Hartvig; Engelbert, Silke; Fotel, Frank Leck; Hoell, E.; Karez, Rolf; Kersting, Kees; Kraufvelin, Patrik; Lindblad, Cecilia; Olsen, Marianne; Sanderud, Knut Arvid; Sommer, Ulrich; Sørensen, Kai

doi:10.1007/s10021-002-0108-6

Cited by 63 publications

(47 citation statements)

References 61 publications

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“…According to the P/B ratios given by Alongi (1990) and Brey (1990), a secondary production of more than 30 kg wet weight may be estimated for each basin per year. With a total basin area of about 15 m 2 , a macroinvertebrate production of 2 kg ww per m 2 per year is realistic as it makes about 10% of the macroalgal production reported by Bokn et al (2003). Considering our estimate that about 8 m 2 per basin are fouled by macroalgae, the production estimate per unit area will be almost twice that amount.…”

Section: Discussionmentioning

confidence: 80%

“…Only few significant effects due to the differences in nutrient addition between the basins were detected at the community level (Bokn et al, 2002(Bokn et al, , 2003Kraufvelin et al, 2002). Slightly higher abundance values were obtained in the small isopod Jaera spp.…”

Section: Discussionmentioning

confidence: 95%

“…As long as the macroalgal community persisted in all the basins, annual grazing could not exceed annual macroalgae production. Further, any grazing preferences could not be detected as long as algal species composition did not undergo dramatic changes throughout the years (Bokn et al, 2002(Bokn et al, , 2003. With high food abundance and high temperatures, other factors may be responsible for the decreasing grazer abundance starting in late summer each year.…”

Section: Discussionmentioning

confidence: 96%

“…As found here, macroalgal associations often have high primary production (Mann, 1982). The system exports both plant biomass (see Bokn et al, 2002Bokn et al, , 2003 and a considerable amount of animals, and the system must be a net exporter of energy (see Hawkins et al, 1992). This high production and export may therefore be important for adjacent systems.…”

Section: Discussionmentioning

confidence: 99%

“…An overall conclusion from running these mesocosms for 5 years was that community structure did not change much, neither throughout time nor due to differences in nutrient supply (Bokn et al, 2002(Bokn et al, , 2003Kraufvelin et al, 2002). The macroalgal assemblages in all basins were dominated by Fucus vesiculosus and F. serratus, while a few species of green algae (mainly Ulva lactuca) and seasonal red algae were common.…”

Section: Introductionmentioning

confidence: 96%

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Mechanisms regulating amphipod population density within macroalgal communities with low predator impact

Christie¹,

Kraufvelin²

2004

Sci. Mar.

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SUMMARY: In eight mesocosms (land based basins) macroalgae communities with associated fauna were transplanted from the sea and established during two years. Then, different doses of nutrients (N and P) were added to the basins throughout the following three years. During the period of nutrient addition, macroinvertebrate grazers showed seasonal fluctuations with densities usually between 500,000 and 1 million individuals per mesocosm during summer and to a level of about 100,000 during winter. The macroinvertebrate grazers mainly consisted of about 10 species of amphipods and isopods, among which the amphipod Gammarus locusta dominated strongly by biomass. Although the number of predators was very low, the grazer populations never reached a density where considerable grazing impact could be found on the macroalgae. No increase in grazer density was found in the basins with improved nutrient conditions. Thus food quality may be insufficient for further population growth, or density dependant regulation mechanisms may have prevented the grazers from flourishing and overgrazing the system. In aquarium experiments we showed that G. locusta could grow and reproduce on Fucus serratus, Ulva lactuca, periphyton and detritus, and that cannibalism by adult G. locusta on juveniles may have great impact on the population growth. The basins were run with a water flow through system. Nets were placed in front of the inflow and outflow tubes to measure immigration and emigration. Only few individuals (and no Gammarus sp.) were recorded in the inflowing water, while high numbers of both amphipods and isopods were found in the outflowing water. Emigration reached peak values during night-time, and it was then two to three times as high as during day-time. Emigration of mobile grazers from the basins amounted to 1-2% of the standing stock daily. These mechanisms that regulate grazers do contribute to maintenance of the seaweed dominance and thus the stability of the seaweed community.Key words: Mesocosm, macroalgae, grazers, Gammarus locusta, population regulation, eutrophication. RESUMEN: MECANISMOS QUE REGULAN LA DENSIDAD DE POBLACIONES DE ANFÍPODOS EN COMUNIDADES DE MACROALGAS CONBAJO IMPACTO DE DEPREDACIÓN. -En ocho mesocosmos (depósitos situados en tierra) se trasplantaron comunidades de macroalgas con fauna asociada procedentes del mar y se establecieron durante dos años. Posteriormente se añadieron diferentes dosis de nutrientes (N y P) a los depósitos a lo largo de los tres años siguientes. Durante el período de adición de nutrientes, los macroinvertebrados herbívoros mostraron fluctuaciones estacionales con densidades que por lo general se encontraban entre 500.000 y 1 millón de individuos por mesocosmos durante el verano y hasta un nivel de unos 100.000 ind. en invierno. Los macroinvertebrados herbívoros eran principalmente unas 10 especies de anfípodos e isópodos, entre los cuales el anfípodo Gammarus locusta dominaba mucho por la biomasa. Aunque el número de depredadores fue muy bajo, las poblaciones de herbívoros no...

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Section: Discussionmentioning

confidence: 80%

Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

See 3 more Smart Citations

Mechanisms regulating amphipod population density within macroalgal communities with low predator impact

Christie¹,

Kraufvelin²

2004

Sci. Mar.

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Testing effects of bottom‐up factors, grazing, and competition on New Zealand rocky intertidal algal communities

Spiecker,

Menge

2024

Ecology and Evolution

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Top‐down and bottom‐up factors and their interaction highlight the interdependence of resources and consumer impacts on food webs and ecosystems. Variation in the strength of upwelling‐mediated ecological controls (i.e., light availability and herbivory) between early and late succession stages is less well understood from the standpoint of influencing algal functional group composition. We experimentally tested the effect of light, grazing, and disturbance on rocky intertidal turf‐forming algal communities. Studies were conducted on the South Island of New Zealand at Raramai on the east coast (a persistent downwelling region) and Twelve Mile Beach on the west coast (an intermittent upwelling region). Herbivory, light availability, and algal cover were manipulated and percent cover of major macroalgal functional groups and sessile invertebrates were measured monthly from October 2017 to March 2018. By distinguishing between algal functional groups and including different starting conditions in our design, we found that the mosaic‐like pattern of bare rock intermingled with diverse turf‐forming algae at Twelve Mile Beach was driven by a complex array of species interactions, including grazing, predation, preemptive competition and interference competition, colonization rates, and these interactions were modulated by light availability and other environmental conditions. Raramai results contrasted with those at Twelve Mile Beach in showing stronger effects of grazing and relatively weak effects of other interactions, low colonization rates of invertebrates, and light effects limited to crustose algae. Our study highlights the potential importance of an upwelling‐mediated 3‐way interaction among herbivory, light availability, and preemption in structuring contrasting low rocky intertidal macroalgal communities.

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Impact of multiple disturbances and stress on the temporal trajectories and resilience of benthic intertidal communities

Cimon

Cusson

2018

Ecosphere

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Coastal ecosystems face severe environmental change and anthropogenic pressures that affect both the structure and functioning of communities. Understanding the response and resilience of communities that face multiple simultaneous disturbances and stresses becomes essential. We observed the recovery of a rocky intertidal subarctic macrobenthic community dominated by a macroalgal canopy (Fucus spp.), a habitat-forming species, over a period of 14 months. Using 0.25-m 2 plots, we ran an in situ onepulse experiment (removal of all materials to bare rock and then burning of the surface) followed by a full orthogonal factorial design of three press-type disturbances or stresses: grazer reduction, canopy removal, and nutrient enrichment. We evaluated the single and interactive effects of the three disturbances and stresses on species diversity and abundance structure. Of all the main effects, canopy removal has the most severe impact, resulting in decreased biomass, richness, and diversity, as well as an altered community structure. Canopy-removed plots had fewer invertebrates and more ephemeral algae; beyond this, however, there was minimal effect from grazer reduction and nutrient enrichment acting individually. We categorized the interaction types of all significant interaction effects: Canopy removal had a dominant effect over grazer reduction on richness, and it also dominated over nutrient enrichment on diversity and evenness. Nutrient enrichment and canopy removal had a negative synergistic interaction effect on richness at the end of the experiment. Without stressors, 11 months were required to achieve full recovery. The three stressors affected recovery time differently, depending on the identity and the number of stressors. Three stressors generally increased the time of recovery or even prevented recovery from being fully attained. Moreover, community structure and composition of plots subjected to the triple-stressor treatment had not fully recovered by the end of the study. Our results suggest that multiple stressors may interact on community indices and structure and that their interaction cannot be predicted from the outcome of single stressor studies. The inclusion of multiple disturbances and stresses in field experiments provides a better understanding of the mechanisms that shape community structure and their functioning following various forms of disturbance.

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The Response of Experimental Rocky Shore Communities to Nutrient Additions

Cited by 63 publications

References 61 publications

Mechanisms regulating amphipod population density within macroalgal communities with low predator impact

Mechanisms regulating amphipod population density within macroalgal communities with low predator impact

Testing effects of bottom‐up factors, grazing, and competition on New Zealand rocky intertidal algal communities

Impact of multiple disturbances and stress on the temporal trajectories and resilience of benthic intertidal communities

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