Reproductive phenology of submerged macrophytes: A tracker of year‐to‐year environmental variations

Abstract

Aims Phenological shifts are useful trackers of climate change effects on species and communities, but few datasets focus on the climate‐driven phenological responses of aquatic ecosystem vegetation. We aimed to analyse the reproductive seasonality of a submerged macrophyte community, the synchrony among coexisting species, and their responses to several environmental factors. Location A Mediterranean coastal pond in Valencia, Spain. Methods We analysed three years of data on a submerged macrophyte community. Plants were collected biweekly or monthly (57 collection dates) to quantify the intensity of flowering/fruiting per species. The reproductive seasonality of the community was tested with circular statistics. The reproductive synchrony of species was calculated with the Augspurger and the Freitas and Bolmgren indexes. The environmental factors driving reproduction in macrophytes were analysed with redundancy analyses. Results The reproductive activity of the community was seasonal (peaking in spring–summer) or non‐seasonal (peaking in spring–summer and autumn) depending on the year‐to‐year variations of precipitations after the summer drought. The synchronization among species in flowering and fruiting (overlap in time and intensity) was low, because the species‐specific reproductive patterns were spread throughout the long Mediterranean growing season. Temperature, water level, and conductivity were the variables that best explained flowering variability in the community, indicating that these factors affected each species differently. Fruiting was temporally correlated to flowering, with different lags depending on the species life cycle. Conclusions The species‐specific responses suggest that a warming climate may act as an environmental filter, gradually changing the community structure. The reproductive phenology of submerged macrophytes could act as an early indicator of a changing climate, with charophytes (Characeae) as suitable tracker candidates. Further studies concerning their phenology are needed to assess the resilience of submerged macrophyte communities to drought and assure the long‐term functioning of Mediterranean aquatic ecosystems.

Sediment underneath charophyte meadows is enriched in viable ephippia and enhances the benthic periphytic biofilm

“…Its smaller oospores will ripen before those of CH. A study on sexual reproduction phenology of CH in an interdunal pond within the Albufera de Vale`ncia Natural Park reported that oospore ripening, after which the oospores detach from the plant and fall down to the sediment, took place predominately in July (Calero & Rodrigo, 2019). The samples in our study were taken in June when the ripening period had not reached its maximum.…”

Changing phenology of benthic primary producers in inland waters: Current knowledge and future directions

“…Being sessile and located at the sediment–water interface, often close to the land–water edge, BPP are also sensitive to human pressure and have been recognized as sentinels of land use change because both biomass and community composition act as indicators of eutrophication (Schneider 2007). Recent studies additionally suggest that long‐term trends and seasonal dynamics in BPP abundance and reproductive traits are sensitive to climate change (Calero and Rodrigo 2019; Vadeboncoeur et al 2021; Botrel and Maranger 2023). The complex interactions among eutrophication, climate change, and food web perturbations have been suggested as an explanation for the mysterious seasonal proliferation of benthic filamentous algae in clear, iconic large lakes such as Baikal and Tahoe (Vadeboncoeur et al 2021).…”

“…Despite the clear temperature effect, other climate‐related factors additionally explained phenology. This was mostly hydrologic regime altering water level, velocity, chemistry, and hydroperiod (e.g., Fernandez‐Zamudio et al 2018; Brahney et al 2021), or the interaction of temperature with hydrology (Calero et al 2018; Calero and Rodrigo 2019). The variability of explanatory factors is analogous to the high variability in the magnitude of shifts per degree observed for phytoplankton (Thackeray et al 2016), reflecting the complex nature of climate impacts on inland waters.…”

Phenological patterns in ecology: Problems using circular statistics and solutions based on simulations

“…Consequently, considerable research has focused on the description of reproductive phenologies and the development of quantitative approaches for uncovering the nature of annual patterns for plants (e.g. Calero & Rodrigo, 2019; Gomes et al., 2019; Lima et al., 2021; Sheldon & Nadkarni, 2015) and animals (e.g. Eghbali & Sharifi, 2023; Hazard et al., 2022; Lima et al., 2021; Nurul‐Ain et al., 2017; Willig, 1985a; Wilson, 1973).…”