Urban ponds require attention to ensure biodiversity

Date:
February 23, 2023
Source:
University of Helsinki
Summary:
New research suggests aquatic plants can be utilized as a tool to
enhance the co-existence between aquatic invertebrates and their
fish predators in urban ponds.


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FULL STORY ========================================================================== Ponds are important part of urban green-blue infrastructure. They
provide city dwellers with many ecosystem services, such as recreation
and supporting biodiversity. Recreation, however, may conflict with
supporting biodiversity.

For example, fish introduced for recreational purposes can reduce the
diversity of aquatic invertebrates, which in turn may limit the value
of urban ponds for aquatic biodiversity conservation.


==========================================================================
A research team at the University of Helsinki investigated how aquatic
plants can be utilised as a tool to enhance the co-existence between
aquatic invertebrates and their fish predators in urban ponds.

Emergent plants, such as sedges, can enhance the occurrence of diving
beetles in a pond. Diving beetles are an indicator taxon of pond
biodiversity, and they have stronger needs for emergent plants as prey
refuges when fish is present in a pond. In ponds with fish, diving
beetles occur when approximately 40% of pond margins are vegetated by
emergent plants, such as sedges and cattails.

For comparison, in ponds with fish, diving beetles already have high
chance to occur when approximately 30% of margins are vegetated. This
is because diving beetles have lower predation risk in ponds without fish.

"In urban ponds, however, aquatic plants are sometimes removed to create
tidy appearance, but it is not really good for biodiversity, because
aquatic invertebrates need plants for various purposes, such as prey
refuges to hide from predators," says researcher and corresponding author Wenfei Liao from the Faculty of Biological and Environmental Sciences, University of Helsinki.

The more aquatic vegetation, the better? Not always! Diving beetles have different needs for emergent plants at different scales. At the pond
scale, diving beetle presence is positively correlated with vegetation
cover.

However, when the team investigated diving beetle diversity in 1mx1m microhabitats in the ponds, they found different patterns: The results
show, at the microhabitat scale, the effects of emergent plant cover on
diving beetle diversity are different between ponds with and without
fish. In ponds with fish, the more vegetation a microhabitat has,
the more diving beetle species and individuals are present. Yet, in
ponds without fish, the diving beetle diversity is not correlated with
emergent plant cover; that is to say, one may find a similar number of
diving beetle species in vegetated spots and non- vegetated spots. This
is because when fish is absent, diving beetles have low predation risk
and can seek food in both vegetated and non-vegetated spots.

"Vegetated spots in urban ponds are good starting places for city people
to observe aquatic insects and understand urban nature. However, we should remember some insects, such as the larvae of some caddisfly species,
may prefer open water; therefore, in aquatic habitat management, it is beneficial to maintain both vegetated and non-vegetated microhabitats to
keep habitat heterogeneity. This is to ensure urban ponds meet the needs
of different aquatic insects and support high aquatic biodiversity,"
concludes Liao.

* RELATED_TOPICS
o Plants_&_Animals
# Ecology_Research # Fish # Endangered_Plants # Fisheries
o Earth_&_Climate
# Biodiversity # Ecology # Ecosystems # Exotic_Species
* RELATED_TERMS
o Fishery o Whale o Water_hyacinth o Fish o Tree_frog o
Algal_bloom o Frog o Phosphate

========================================================================== Story Source: Materials provided by University_of_Helsinki. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Wenfei Liao, Stephen Venn, Jari Niemel�. Microhabitats
with
emergent plants counterbalance the negative effects of fish
presence on diving beetle (Coleoptera: Dytiscidae) diversity in
urban ponds. Global Ecology and Conservation, 2023; 41: e02361 DOI:
10.1016/ j.gecco.2022.e02361 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/02/230223132904.htm

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