How pondscapes function: Connectivity matters for biodiversity even
across small spatial scales in aquatic metacommunities
Abstract
Habitat loss and fragmentation are growing global threats to natural
habitats and their networks, posing significant challenges to
biodiversity conservation. Among the most vulnerable ecosystems, ponds
stand out due to their small sizes exhibiting global declines in numbers
and extent. While it is generally agreed that connectivity in habitat
networks is crucial for sustaining biodiversity, the effect of
connectivity on biodiversity patterns over small-scaled habitat networks
has so far received less attention given the general assumption that
metacommunities lack spatial structuring on small scales. In this study,
we tested whether this holds for multiple passively and actively
dispersing organism groups in a well-delineated pond metacommunity of 54
bomb crater ponds situated within 1 km. We investigated the influence of
space and environment on species richness and metacommunity structure in
these ponds, which share similar age, size, and shape and are subject to
strong environmental gradients, making it an ideal study system. We
specifically examined the impact of network centrality on species
richness and eigenvector-based spatial arrangement on metacommunity
structure across different organism groups, including prokaryotes,
microeukaryotes, zooplankton, macroinvertebrates, and amphibians. We
found that while environmental filtering is the primary driver of
community dynamics, there is also a significant spatial signal,
particularly for passively dispersing groups, demonstrating the role of
the central-peripheral connectivity gradient. These findings highlight
the importance of studying and protecting ponds as parts of a network
rather than focusing on individual ponds.
Keywords: multi-group, spatial network, centrality, zooplankton,
microbe, invertebrate, dispersal