Winter is coming: Food web structure and seasonality in a subtropical freshwater coastal lake

Abstract

Food web studies provide a useful tool to assess the organization and complexity of natural communities. Nevertheless, the seasonal dynamics of food web properties, their environmental correlates, and potential association with community diversity and stability remain poorly studied. Here, we condensed an incomplete 6‐year community dataset of a subtropical coastal lake to examine how monthly variation in diversity impacts food web structure over an idealized time series for an averaged year. Phytoplankton, zooplankton, macroinvertebrates, and fish were mostly resolved to species level (n = 120 trophospecies). Our results showed that the seasonal organization of the food web could be aggregated into two clusters of months grouped here as ‘summer’ and ‘winter’. During ‘winter’, the food web decreases in size and complexity, with the number of trophospecies dropping from 106 to 82 (a 22.6% decrease in the number of nodes) and the trophic interactions from 1,049 to 637 between month extremes (a 39.3% drop in the number of links). The observed simplification in food web structure during ‘winter’ suggests that community stability is more vulnerable to the impact of any change during this period.

Mapping Micro-Pollutants and Their Impacts on the Size Structure of Streambed Communities

“…Subsequently, we evaluated the degree to which the number and concentration of EOCs and dissolved compounds such as nutrients were associated with the ordination axis. For this, we fitted all environmental variables collected originally (Table S1) and new data on profiles and concentrations of EOCs onto the resulting two-dimensional ordination following Peralta-Maraver et al [35]. Degree correlation and significance of the association between fitted variables and the ordination axis was then assessed after a 1000 randomized permutation test.…”

Variable littoral‐pelagic coupling as a food‐web response to seasonal changes in pelagic primary production

“…Our study shows seasonal forcing is also a strong driver of littoral‐pelagic coupling. Seasonal diet switching results from temporally differentiated resource pulses (Dalu, Wasserman, Froneman, & Weyl, ; Hayden, Harrod, & Kahilainen, ; Mazumder, Saintilan, Wen, Kobayashi, & Rogers, ; Peralta‐Maraver et al., ). These dynamics need to be considered for defining trophic structure.…”

“…An increasing number of studies in a diverse range of aquatic systems have demonstrated food‐web responses to seasonal changes in productivity (see: Dalu, Wasserman, Froneman, & Weyl, ; Hayden, Harrod, & Kahilainen, ; Peralta‐Maraver et al., ). In smaller lakes, dietary shifts of predators to littoral and terrestrial resources have been observed when pelagic productivity declines (Dalu et al., ; Eloranta et al., ; Peralta‐Maraver et al., ). However, similar observations are lacking in large lakes which have a relatively high proportion of pelagic: littoral habitat with strong seasonal variations in primary production (Vadeboncoeur, Peterson, Vander Zanden, & Kalff, ) is lacking.…”

Environmental factors are the major drivers of macroinvertebrate assemblage structure in southern Brazilian coastal lakes

“…The southern Brazilian Coastal Plain harbours a large chain of freshwater shallow lakes that support high biological diversity and a variety of ecosystem services (Lanzer et al, 2017;Schäfer et al, 2013Schäfer et al, , 2017. Although macroinvertebrate diversity was inventoried (Lima et al, 2013;Schäfer et al, 2009Schäfer et al, , 2013Schäfer et al, , 2017Volkmer-Ribeiro & Rosa-Barbosa, 2007), and other studies assessed the food web structure and temporal variation of macroinvertebrate assemblages in many lakes (Lemes da Silva et al, 2016;Peralta-Maraver et al, 2017), no study assessed the drivers of macroinvertebrate assemblages in the Coastal Plain region. In addition, the southern Brazilian Coastal Plain has been increasingly subject to anthropogenic pressures (e.g.…”