Effect of production and biomass of intertidal microphytobenthos on meiofaunal grazing rates

• Published in: Journal of experimental marine biology and ecology Vol. 185; no. 2; pp. 149 - 165
• Main Authors: Montagna, Paul A., Blanchard, Gérard F., Dinet, Alain
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 13.02.1995; Elsevier Science
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Chlorophyll; Functional response; Fundamental and applied biological sciences. Psychology; Grazing; Intertidal mudflat; Meiobenthos; Microphytobenthos; Sea water ecosystems; Synecology; Poitou-Charente; Charente-Maritime; Bay of Biscay; Europe; Atlantic Ocean; North Atlantic; France; Chlorophyll; Meiobenthos; Functional response; Grazing; Microphytobenthos; Intertidal mudflat; Marine environment; Primary productivity; Intertidal zone; Food intake; Animal plant relation; Tidal flat; Browsing; Trophic relation; Biomass; Phytobenthos
• ISSN: 0022-0981; 1879-1697
• DOI: 10.1016/0022-0981(94)00138-4

Microphytobenthos dominate primary production in unvegetated intertidal habitats. Meiofauna are likely to be important consumers of this productivity, yet little is known about meiofauna herbivory in these environments. We studied meiofaunal grazing on microphytobenthos from an intertidal mudflat on the southwest coast of France. Meiofaunal grazing rates were measured in response to manipulations that varied microphytobenthos production and biomass to determine if meiofauna have functional responses to changes in food quality and quantity. Harpacticoid and ostracod grazing rates did not change in response to changes of microphytobenthos production, but nematode grazing rates did increase with increasing production. As microphytobenthos biomass increased, meiofauna responded with greater grazing rates, removing more biomass per unit time, yet taking longer periods of time to deplete (or clear) the microbial population. Therefore, meiofauna taxa exhibited functional responses to microphytobenthos as food, although different taxa had different responses. The impact of these responses in the laboratory could be seen in the field. For example, when chlorophyll a (Chl a) concentration in the top 1 cm of sediment increased from 31.7 mg · m −2 to 124 mg · m −2 2 wk later, the total community grazing rates increased from 32.9 ng Chl a · h −1 to 176 ng Chl a · h −1 . Harpacticoid densities also increased 2.7 times, but nematode and ostracod densities remained the same. The results of this study support the idea that intertidal meiofauna, particularly harpacticoids, have a dependent relationship with their autotrophic food resources in intertidal habitats and can regulate their behavior to maximize intake of food.