The ability to get everywhere: dispersal modes of free-living, aquatic nematodes

Abstract

Nematodes colonize almost all aquatic habitats worldwide. Despite their small size, restricted locomotion and lack of pelagic larvae, they can reach even isolated habitats within a short time. In this review, we examine the underlying dispersal modes, considering their active movement in substrates and water, their drift by water and wind, rafting, zoochory as well as human-mediated vectors. These modes are limited by morphology and habitat structure, ecological factors and especially by hydrodynamics. Active dispersal is effective over short distances, but with increasing water-flow velocity, passive dispersal modes, which enable long-range transfer, become important. In fact, the transport of nematodes over thousands of kilometers via ship water tanks and by hitchhiking on sea turtles has been documented. Overland dispersal vectors include wind and birds whereas rafting enables an aggregated distribution because food is available, and reproduction is possible onboard the rafts. The diversity of possible dispersal modes is high and offers a reasonably chance for gravid females or groups of nematodes to be transferred even to remote environments. Their immigration is continuous, and supported by their rapid, parthenogenetic reproduction, nematodes are effective pioneers with the ability to (re)colonize new or disturbed habitats or rebalance already existing communities.

Hadal Mud Dragons: First Insight Into the Diversity of Kinorhyncha From the Atacama Trench

“…The potential of gene flow of pan-oceanic scale has been already documented for some benthic deepsea taxa (Eustace et al, 2016;LaBella et al, 2017), including meiofaunal organisms (Pawlowski et al, 2007;Bik et al, 2010;Fontaneto, 2019 and references therein). Hence, similarities between geographically distinct species is highly possible, as a result of incomplete lineage sorting following the historicaltectonic movements (e.g., formation of the Isthmus of Panama) or dispersal over large distance, e.g., through thermohaline circulation (Pawlowski et al, 2007;Ptatscheck and Traunspurger, 2020). The latter may seem even more likely, as in the material from abyssal station at 4050 m we found E. pterus.…”

Connectivity of communities interacts with regional heterogeneity in driving species diversity: a mesocosm experiment

“…S4) either survived at very low abundances or entered a dormant stage (such as eggs) until the competitive pressure of the invaders stopped. This ability may be common for nematodes, as many species are able to at least partly resist unfavorable conditions for as long as decades (Ptatscheck and Traunspurger 2020). Generally, this result suggests that dispersal-induced diversity changes can be reversed rather quickly.…”

Diversity patterns of free-living nematode assemblages in seagrass beds from the Cuban archipelago (Caribbean Sea)

“…However, aquatic nematodes may disperse to long distances by the combination of diverse modes of dispersal (e.g. passive dispersal by currents, zoochory) with rapid reproduction ( Ptatscheck and Traunspurger 2020 ). The differences in the DDS pattern between exposed and sheltered sites suggest that dispersal by hydrodynamics plays a significant role.…”

“…Dispersal of marine nematodes is substantial at scales of 10–100 km as indicated by genetic data ( Derycke et al 2013 ). A recent review ( Ptatscheck and Traunspurger 2020 ) concluded that nematodes are effective colonisers due to the diversity of dispersal modes, continuous immigration and rapid reproduction.…”