Phytoplankton functional group dynamics explain species abundance distribution in a directionally changing environment

Summary Flower and seed production of plants can be greatly influenced by both natural climatic oscillations and local weather extremes. However, owing to the rarity of long‐term monitoring studies conducted at a sufficient temporal scale to capture climatic oscillations and the unpredictability of extreme weather events, evidence that demonstrates how these two external forcings act in concert to drive plant reproduction remains scarce. In addition, considerable variation in species' phenological responses to the external climatic forcings was often observed. Phylogenetic relationships may mediate this interspecific variation, but previous studies yielded inconsistent results when testing this hypothesis. We monitored the flower and seed production in a subtropical rain forest, Fushan, Taiwan (24°45′N, 121°35′E), for over 10 years (since September 2002). In March 2005, a record low temperature (−1.3 °C) occurred at Fushan and caused great frost damage to plants. We used weekly phenological records and long‐term meteorological data to assess the effects of climatic fluctuations and extreme weather event on plant reproductive output. We show that the El Niño Southern Oscillation (ENSO) indices, which integrated local climatic variables at Fushan over several months, were strongly associated with flower and seed production. The 2005 spring frost also had long‐lasting effects on the flower and seed production of several species. In particular, we detected phylogenetic signals in the relationships between phenological responses of flowering production and several climatic variables (maximum temperature, irradiance and ENSO34 index). By contrast, the relationships between seed production and climatic variables, as well as phenological responses to the frost event, did not exhibit a phylogenetic signal. Synthesis. Our findings add to the growing evidence that together the natural climatic oscillation (ENSO) and the extreme weather event (frost) determined the temporal variation in flower and seed production. In addition, phylogenetically closely related species resembled each other in their flowering responses to abiotic variation in this subtropical rain forest. Improved understanding of these abiotic and biotic interactions may help predicting population‐ and community‐level phenological responses under future climate changes.

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“…; Patton, Politis & White ; Tsai et al . ). The bootstrap procedure starts from randomly drawing a number X 1 from the original time series.…”

Section: Methodsmentioning

confidence: 97%

ENSO and frost codetermine decade‐long temporal variation in flower and seed production in a subtropical rain forest

et al. 2015

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“…According to previous dietary analyses, the fish feeds mainly on zooplankton and zoobenthos (gammarids) (Nakanishi & Nagoshi 1984;Briones et al 2012). A major advantage of using this fish species is that unique long-term data were available on prey compositions in both predator diet and the environment (Ishikawa, Narita & Urabe 2004;Nakazawa et al 2010;Hsieh et al 2011;Briones et al 2012;Tsai et al 2014).…”

Section: P R E D a T O R S P E C I E Smentioning

confidence: 99%

“…Long-term data were compiled on individual body size of G. isaza (Nakazawa et al 2010), relative composition and body sizes of its major prey (zooplankton and gammarids) in the guts (Briones et al 2012), and relative prey abundances in the environment (Ishikawa, Narita & Urabe 2004;Hsieh et al 2011;Tsai et al 2014), as described below.…”

Section: A T a C O L L E C T I O Nmentioning

confidence: 99%

“…These prey types comprised about 94% of all recorded predation events and, therefore, the exclusion of other minor preys is unlikely to have affected our conclusion. To evaluate relative prey compositions in the environment, literature data on annual average abundances of gammarids (Ishikawa, Narita & Urabe 2004) and six categories of zooplankton (Hsieh et al 2011;Tsai et al 2014) were used, which were available for the period of 1966-2004 (excluding 2000) and 1962-2004 for gammarids and zooplankton, respectively. Although fish samples were collected in winter and prey abundances were annually averaged, it would not really matter in our analysis because annually averaged and seasonal measurements show similar interannual variations due to the general robustness of seasonality and effects of seasonality can be ignored in long-term data analysis such as ours (Chatfield 2003).…”

Section: A T a C O L L E C T I O Nmentioning

confidence: 99%

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Predator–prey mass ratio revisited: does preference of relative prey body size depend on individual predator size?

2016

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Summary Quantifying predator–prey body size relationships is key to understanding food webs. Food web models often assume that all individuals of predator species prefer the same relative body size of prey, using a single constant called preferred predator–prey mass ratio (preferred PPMR). In contrast, empirical studies have shown that relative prey body size in diet varies with individual predator size, challenging the food web models based on size‐invariant preferred PPMR and their predictions. We point out that this apparent inconsistency arises because empirical PPMR in those previous studies has been measured only through dietary data (i.e. realized PPMR rather than preferred PPMR) without considering the effects of environmental prey availability, suggesting the possibility that preferred PPMR may be in fact independent of individual predator size. Here, we present a new approach to revisit the assumption of size‐invariant preferred PPMR in food web models. The approach compares two measures of PPMR calculated from prey compositions in predator diet and environmental prey composition, respectively (i.e. realized PPMR vs. environmental PPMR). The deviations between realized and environmental PPMRs are considered as a proxy of individual variations in relative prey size preference (i.e. preferred PPMR). We apply this idea to long‐term dietary data of an omnivorous predatory fish species collected from a lake ecosystem over four decades. Our results showed that the preferred PPMR is independent of individual predator size when the foraging mode (i.e. the major prey type) of the predator is considered while the realized PPMR is size‐dependent regardless of the foraging mode, especially when analysed analogously to previous empirical studies. We suggest that the apparent inconsistency between theoretical assumption and empirical observation of PPMR is due to the conceptual and methodological confusion and could be resolved by distinguishing between preferred and realized PPMRs. Further, in contrast to the previous arguments based on realized PPMR, we provide the first empirical support for size‐invariant preferred PPMR. Future studies are encouraged to apply our ideas to other species/systems to test the robustness of size‐invariant preferred PPMR and to better describe food web models. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12680/suppinfo is available for this article.

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“…Consequently, phosphorous concentrations in many lakes have declined immensely (Anneville, Gammeter, & Straile, 2005;Pomati et al, 2012;Van Donk et al, 2008). This has, for example, been well studied in Lake Biwa, Japan, for which both biotic and abiotic variables have been tracked over 32 years, showing an increase in nutrient loading in the 1960s and 1970s, followed by a decline during the 1980s, when management practices showed effect (Hsieh et al, 2010;Tsai et al, 2014). High nutrient concentrations are often characterized by high biomass production by few dominant species (Borge et al, 2004), whereas re-oligotrophication increases species richness and community evenness (Pomati et al, 2012) coupled with a decrease in autotrophic productivity or standing stocks (Finger, Wuest, & Bossard, 2013;Verbeek et al, 2018).…”

mentioning

confidence: 99%

Warming and oligotrophication cause shifts in freshwater phytoplankton communities

Verbeek

Gall

Hillebrand

et al. 2018

Global Change Biology

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While there is a lot of data on interactive effects of eutrophication and warming, to date, we lack data to generate reliable predictions concerning possible effects of nutrient decrease and temperature increase on community composition and functional responses. In recent years, a wide-ranging trend of nutrient decrease (re-oligotrophication) was reported for freshwater systems. Small lakes and ponds, in particular, show rapid responses to anthropogenic pressures and became model systems to investigate single as well as synergistic effects of warming and fertilization in situ and in experiments. Therefore, we set up an experiment to investigate the single as well as the interactive effects of nutrient reduction and gradual temperature increase on a natural freshwater phytoplankton community, using an experimental indoor mesocosm setup. Biomass production initially increased with warming but decreased with nutrient depletion. If nutrient supply was constant, biomass increased further, especially under warming conditions. Under low nutrient supply, we found a sharp transition from initially positive effects of warming to negative effects when resources became scarce. Warming reduced phytoplankton richness and evenness, whereas nutrient reduction at ambient temperature had positive effects on diversity. Our results indicate that temperature effects on freshwater systems will be altered by nutrient availability. These interactive effects of energy increase and resource decrease have major impacts on biodiversity and ecosystem function and thus need to be considered in environmental management plans.

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Phytoplankton functional group dynamics explain species abundance distribution in a directionally changing environment

Cited by 18 publications

References 56 publications

ENSO and frost codetermine decade‐long temporal variation in flower and seed production in a subtropical rain forest

ENSO and frost codetermine decade‐long temporal variation in flower and seed production in a subtropical rain forest

Predator–prey mass ratio revisited: does preference of relative prey body size depend on individual predator size?

Warming and oligotrophication cause shifts in freshwater phytoplankton communities

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