Associations between submerged macrophytes and fish communities at two spatial scales in 88 temperate shallow lakes

Abstract

Fish community structure is affected by a range of lake characteristics, including the cover of macrophytes that provide spawning habitats, nursery area, refuge against predators, and food. We assessed fish–macrophyte relationships at both lake and point scale using an extensive dataset from 88 Danish shallow lakes (maximum depth ≤4.5 m). At lake scale, we used mean values from fish and macrophyte community samples for all lakes, in total 88 samples. The point scale data were derived from multiple points in each lake (in total 595 samples) where both macrophytes and fish were sampled, allowing us to assess within‐lake variations. We found generally negative relationships between macrophyte cover and fish abundance and biomass, which was strongest at point scale. Contrary to macrophytes, chlorophyll a showed positive relationships with fish abundance—except for perch and all fish <10 cm, which did not show significant relationships. The deeper and more eutrophic the lakes, the more the fish tended to occupy points covered by macrophytes. The abundances of species such as roach and bream were negatively related to macrophyte cover, but, for perch, this relationship was not significant. Our results suggest that fish abundance and biomass were associated with a combination of factors that are often intercorrelated and difficult to isolate. The relationship between fish abundance and biomass and macrophyte cover may depend on, among other factors, fish species, fish size, and the characteristics of the individual lakes.

Creating wetland islands to enhance shoreline habitat for fish recruitment in a modified shallow lake

“…Littoral vegetation and submerged macrophytes may also contribute to favourable benthic and pelagic food conditions for young‐of‐the‐year fishes (van Leeuwen et al, 2023b), especially for perch (Čech et al, 2012). Such habitat diversity may lead to complex interactions between food availability and predation risk, including the occurrence of diel movements of young fishes that depend on macrophyte cover and turbidity (Quirino et al, 2023). Generally, a mosaic landscape of shallow sheltered shore zones combined with shallow sheltered bays with submerged vegetation thus offers important spawning and/or nursery habitats for a variety of fish species.…”

“…Generally, a mosaic landscape of shallow sheltered shore zones combined with shallow sheltered bays with submerged vegetation thus offers important spawning and/or nursery habitats for a variety of fish species. These habitats provide suitable water temperatures for growth in spring, high food availability, and shelter both from wave action and predators (Čech et al, 2012; Jennings et al, 1999; Quirino et al, 2023; Radinger et al, 2023; Winfield, 2004).…”

“…This movement could not be further substantiated because of limited options to sample small fishes in these habitats; unstable sediments (quicksand) limited accessibility, and dense vegetation limited the use of seine nets. Many other studies, however, demonstrated that young-of-the-year fishes may benefit from submerged macrophytes as a refuge against predators ( Čech et al, 2012;Quirino et al, 2023;Radinger et al, 2023). Recent telemetry studies demonstrate that piscivorous fishes (van Leeuwen et al, 2023a) and piscivorous wading birds such as the spoonbill (Platalea leucorodia) and herons Ardea spp.…”