Navigating through space and time: A methodological approach to quantify spatiotemporal connectivity using stream flow data as a case study

Abstract

1. The growing interest in combining spatial and temporal patterns in nature has been fostered by the current availability of high-frequency measurements. However, we still lack a methodological framework to process and interpret spatiotemporal datasets into meaningful values, adaptable to different time windows and/or responding to different spatial structures. Here, we developed and tested a framework to evaluate spatiotemporal connectivity using two new measures: the spatiotemporal connectivity (STcon) and the spatiotemporal connectivity matrix (STconmat).2. To obtain these measures, we consider a set of spatially connected sites within a temporally dynamic network. These measures are calculated from a spatiotemporal matrix where spatial and temporal connections across sites are captured.These connections respond to a determined network structure, assign different values to these connections and generate different scenarios from which we obtain the spatiotemporal connectivity. We developed these measures by using a dataset of stream flow state spanning a 513-day period obtained from data loggers installed in seven temporary streams. These measures allowed us to characterise connectivity among stream reaches and relate spatiotemporal patterns with macroinvertebrate community structure and composition. Spatiotemporal connectivity differed within and among streams, with STconand STconmat capturing different hydrological patterns. Macroinvertebrate richness and diversity were higher in more spatiotemporally connected sites.

Characterizing Space‐Time Channel Network Dynamics in a Mediterranean Intermittent Catchment of Central Italy Combining Visual Surveys and Cameras

“…Moreover, the separation between wet/dry/ponding conditions might not be operationally simple to define in some cases. In previous works pools were either considered as part of the wet nodes (Cunillera‐Montcusí et al., 2023) or were excluded from the computation of the wet length of the network (Durighetto et al., 2020; Ilja Van Meerveld et al., 2019; Senatore et al., 2021). The latter seems to be a reasonable option, provided that only the flowing streams contribute to the active transport of water and matter downstream.…”

Integrating spatiotemporal hydrological connectivity into conservation planning to protect temporary rivers

“…A presence/absence of water dataset was utilized to calculate spatiotemporal hydrological connectivity variables (hereafter STcon) for each sampling site, and considering the two scenarios proposed in Cunillera‐Montcusí et al (2023): a binary scenario (i.e., connection between sites as 1 and no connection as 0) and a weighted scenario (i.e., connection between sites weighted by the Euclidean distance between them). In addition, two types of network structures were considered for each of these two scenarios: directed (i.e., with an upstream to downstream directionality) and undirected (i.e., where all sites are connected between each other).…”

“…As distances between sampling sites for each stream were small, and streams were relatively straight, Euclidean distances could be used to weight both Binary and Undirected scenarios. See more details about STcon in Cunillera‐Montcusí et al (2023).…”

“…TRs are one of the most common freshwater habitats in the planet (Messager et al, 2021), and they are expected to become even more widespread in the future because of water scarcity (Kumar et al, 2014;Mekonnen & Hoekstra, 2016;van Vliet et al, 2021). TRs are characterised by shifting wet and dry phases (Gallart et al, 2012), which change spatiotemporal hydrological connectivity (Cunillera-Montcusí et al, 2023), constraint species dispersal, and affect metacommunity dynamics (Cañedo-Argüelles et al, 2020). This dynamism can have challenging implications for the conservation and biomonitoring of TRs (Datry et al, 2023) because available habitats and species to be potentially protected and/or used as bioindicators change dramatically in space and through time.…”