Independent Gradients of Producer, Consumer, and Microbial Diversity in Lake Plankton

Abstract

Abstract. Interactions between trophic levels during food web assembly can drive positive correlations in diversity between producers, consumers, and decomposers. However, the contribution of trophic interactions relative to local environmental factors in promoting species diversity is poorly understood, with many studies only considering two trophic levels. Here we examine correlations in diversity among zooplankton, phytoplankton, and bacteria in the pelagic zone of 31 lakes in British Columbia, Canada. We sampled species diversity of zooplankton and phytoplankton through morphological identification, and bacterial genetic diversity was estimated by denaturing gradient gel electrophoresis (DGGE) of 16S rDNA polymorphisms. We looked for correlations in diversity that were independent of the abiotic environment by statistically controlling for 18 limnological variables. No significant correlations were found between the diversity of zooplankton, phytoplankton, and bacteria. In addition, the physical factors that were associated with species composition in one trophic level were independent of those that were important for another. Our results provide no support for the importance of direct feedbacks between producers, consumers, and decomposers in maintaining diversity. Zooplankton, phytoplankton, and bacterial diversity and composition are regulated independently from one another and respond to different environmental variables. These results suggest that species of lake plankton show loose trophic associations with one another due to broad diets in consumers and decomposers.

Disentangling the spatial patterns in community composition of prokaryotic and eukaryotic lake plankton

“…Higher trophic levels, such as zooplankton that graze on phytoplankton, may be more strongly regulated by food-web interactions or top-down forces (McQueen et al 1989). In RDA, the finding that nutrient supply is the dominant factor influencing community composition of phytoplankton agrees with Longmuir et al (2007), who documented that trophic status of the lake was the strongest determinant of phytoplankton community structure in lakes in British Columbia, Canada. In spite of a strong correlation with the local environment, phytoplankton communities were also spatially structured.…”

“…The samples were collected at 0.5 m below the surface of the water. Our sampling protocol for bacteria followed the procedure by Longmuir et al (2007). First, a 250-mL sample of water was filtered through a 0.42-mm pore-size nitrocellulose filter (diameter 25 mm; Millipore, DuraporeH) to remove larger particles.…”

PCR‐DGGE Fingerprinting Analysis of Plankton Communities and Its Relationship to Lake Trophic Status

“…To investigate relationships between DGGE fingerprints of plankton communities and measured environmental factors, CCA was performed using the software program CANOCO, version 4.5 (TER BRAAK, 1988). CCA has commonly been used to infer speciesenvironment relationships and to find the pattern that is best explained by a particular environmental variable (TER BRAAK, 1986;LONGMUIR et al, 2007). The obtained ordination axes (based on community composition data) are linear combinations of environmental factors, assuming a unimodal species -environment relationship.…”

Distribution of cultivable bacterial communities in two eutrophic aquatic ecosystems, eastern China

“…TP, WSP, BOD 5 , and COD Mn represent the amount of phosphorus and carbon source and are usually thought to be a stimulating factor for bacterial growth. The negative correlation suggests that there must be other critical factors in controlling bacterial abundance; this role may be played by phytoplankton or zooplankton (Longmuir et al, 2007).…”

“…Mudryk and Donderski (1997) reported that most of the planktonic bacteria in shallow estuarine lakes had the abilities to hydrolyze proteins, lipids, and starch, while chitinolytic bacteria and nucleic acid-hydrolyzing bacteria were less numerous, and moreover that cellulose-hydrolyzing microbes were the least abundant group of organisms. Longmuir et al (2007) compared biotic and chemical parameters of 31 lakes in Canada and suggested that species of lake plankton show loose trophic associations with one another due to the existence of consumers. Cebron and Garnier (2005) investigated nitrifying bacteria in the Seine River (France) and found that the genus Nitrosomonas was the predominant community of ammonia-oxidizing bacteria, and the genera Nitrobacter and Nitrospira were representatives of nitrite-oxidizing bacteria.…”