What is a macrophyte patch? Patch identification in aquatic ecosystems and guidelines for consistent delineation

Abstract

Patches are of central interest to many areas of environmental science because they provide a lower limit of structural detail in synoptic studies, and an upper limit of contextual structure for point measurement-based studies. Identification and delineation of macrophyte patches however, is often arbitrary and case-specific. In this paper we propose a widely-applicable set of guidelines for delineating a "patch" and "patch matrix"the latter implying a collection of interacting patches which could standardize future research. To support this proposal, we examine examples from eco-hydrological studies, focusing on interactions between plants, water flow, sediment, and invertebrates. We discuss three aspects that are key to the delineation of a patch: (1) constitution (variable(s) whose values define the patch), (2) spatial properties (patch boundaries), and (3) distinction (of isolated single patches from multiple separate-but-interacting patches). The discussion of these aspects results in guidelines for identifying and delineating a patch which is

Microhabitat preferences of fish assemblages in the Udzungwa Mountains (Eastern Africa)

“…Furthermore, Barbus spp. and Mormyridae usually have a clear preference for vegetated inshore microhabitats (Bell‐Cross & Minshull, ; Worthington, ), which is in agreement with the most relevant cover types indicated by the chi‐square test (see Supporting information Appendix S1) that are prone to occur near banks (Schoelynck et al, ). In contrast, we observed that C. deckenii may not follow the same habitat preferences as other related species that usually show a clear habitat preference for rapids (Eccles, ; Gaigher, ; Roberts, ; Schmidt, Bart, & Nyingi, ).…”

Environmental control of macrophyte traits and interactions with metabolism and hydromorphology in a groundwater‐fed river

“…Macrophyte patches can consist of one or multiple species, and they can be clearly or poorly delineated. More importantly, macrophyte patches can act as one hydrodynamic patch in their interaction with flow velocity, which increases their influence in river processes, that is, it is more than expected when looking at just plant coverage (Schoelynck et al, 2018). Macrophytes growing in self‐organized patches may also be less vulnerable to sudden changes in discharge than homogeneous vegetation (Cornacchia et al, 2020).…”

Biophysical Interactions in Fragmented Marine Canopies: Fundamental Processes, Consequences, and Upscaling

“…However, at times their edges are indistinct, and at others it is not clear whether a canopy distribution is a single but morphologically-complex patch, or a mosaic of several individual patches. For further discussion on this issue, the reader is directed toward Schoelynck et al (2018). Hereinafter, I will assume that patch and gap edges are clearly defined.…”

“…Although significant progress has been made in this area in recent years there still remains much to be done. Further studies are needed into the mechanics of interactions between multiple canopy patches and gaps at all scales -from interactions between two patches, through studies of patch mosaics (Schoelynck et al, 2018) and fragmented canopies with more complex spatial distributions, to whole-landscape scales. These need to take into account the roles of a wide range of different variables, including those related to hydrodynamics (waves, currents, turbulent mixing), sediment (erosion, resuspension, transport, deposition), and other physical variables such as light levels (e.g., Koch, 2001;Adams et al, 2016) and water temperature.…”