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Movement (ecology)In ecology, movement can be defined as the process of biota travelling from one place to another and helps explain random, regular or aggregated patterns of distribution[3]. The modes of movement (often termed dispersal modes) can be classified into two main groups: active or passive The routine movement of an individual within an area is known as its home range and is where it would undertake its normal activity. Dispersal is where an individual moves to an area outside its home range with no predictable direction or return. Dispersal may be driven by processes such as tides, currents, winds and gravity. For example dispersal of pelagic larvae relies on currents and eddies that maintain the larvae either close to their source or disperse them across the currents. 
In sessile organisms (such as plants or oysters which are attached to a substrate) passive movement can occur using the mechanisms of gravity, wind, water, and animals. For example, many mangroves have seeds that float away on the water to germinate elsewhere[7] and freshwater mussels can move around at their larval stage (glochidia) by attaching to fish gills and fins[2]. The movement of mobile or active organisms (such as waterbirds, insects, mammals, fish) occurs using other mechanisms such as flying, swimming and walking. Animals move to enhance their reproductive opportunities and to increase access to necessary resources or avoiding exposure to adverse biotic or abiotic conditions[5]. The nature and degree of movement represents a balance between costs and benefits. Moving is energetically expensive and exposes individuals to substantially elevated risks of mortality. However, movement to exploit abundant resources or to avoid stressors within the home range can result in energetic and survival advantages. Connectivity of habitat and hydrology is vitally important for movement of aquatic biota. In highly variable aquatic environments, like Queensland’s many intermittently flowing rivers and streams, it is sometimes advantageous to move, and at other times remain in an area, depending on environmental conditions. Due to the range of variables involved there is large individual variation in movement behaviour within populations, for example of fishes in dryland rivers[8]. Diversity of movement behaviours between individuals in a population living in a variable environment is an example of the ecological concept of ‘portfolio effects’ whereby a subset of individuals adopt suitable behaviours to benefit under a diversity of possible future conditions. This allows populations to remain viable in variable environments and fluctuating advantage maintains the diversity of individual movement behaviours[9]. Wetland biota move in response to environmental influences including daylight, precipitation, inundation, shading and temperature. Most living things have a body clock with fundamental movements around day and night, for example the plankton which rise from the deep to the shallows at night. As well as responding to the above environmental influences, intertidal and subtidal biota movements are influenced by the tides and the lunar cycle. The rising tide activates intertidal periwinkle snails to creep up the rocky shores to feed on algae, retreating to crevices to avoid desiccation and predators as the tide recedes[11]. High tide provides an opportunity for fish such as coral reef fish to feed across adjacent seascapes including seagrass and mangroves and tidal flats[10]. Juvenile fish such as whiting move into the shallows on rising tides, when it retreats remaining in shallow pools that provide a refuge from predators[6]. Some aquatic species migrate between fresh and salt water to complete their life cycle[1]. This migration is termed diadromy and there are three categories of diadromous species - catadromous, anadromous, and amphidromous. Catadromous species are spawned in marine habitats and migrate to freshwater areas for the majority of their adult life, but return to marine environments to reproduce. Examples in Queensland include barramundi (Lates calcarifer), Australian bass (Macquaria novemaculeata), sea mullet (Mugil cephalus), freshwater eels (Anguilla spp.), jungle perch (Kuhlia rupestri) and tarpon (Megalops cyprinoides)[1]. Anadromous species are spawned in freshwater habitats, and spend their juvenile lives in freshwater, but migrate to marine environments to spend their adult life. These species migrate back to the freshwater environment (upstream migration) to reproduce[1]. The time spent in either habitat varies between species, and the distance travelled also varies from short distances to hundreds of kilometres. In addition to having access to these habitats, aquatic species must also undertake physiological adjustments when moving from freshwater to salty (marine) waters. Amphidromous species are spawned in fresh, brackish or marine waters and move between water types after hatching for reasons other than reproduction. Examples of amphidromous Queensland fish species include freshwater amphidromous cling gobies (e.g. Stiphodon spp.), which are spawned in freshwater but young larvae are washed downstream to the sea and return to freshwater as juveniles, and marine amphidromous mangrove jack (Lutjanus argentimaculatus), which spawn in marine waters but juveniles often inhabit the lower freshwater reaches of rivers[1]. Most native fish species that complete their lifecycle wholly in freshwater also have a requirement for movement within river systems. This type of migration is termed potamodromous and in Queensland is undertaken by fish such as golden perch (Macquaria ambigua) and silver perch (Bidyanus bidyanus). Potamodromous species often spawn in upstream freshwater habitats and drift downstream (while remaining in freshwater) as larvae but return to upstream freshwater habitats to spawn[1]. Oceanodromous fish remain in marine environments. They spawn in particular areas, drift on ocean currents as larvae, and settle as juveniles to grow into adults. They migrate back to the spawning grounds to spawn. Tailor (Pomatomus saltatrix) are a well-known Queensland oceanodromous species.
Links and referencesMovement - managing waterbirds for ecological requirements Wetlands in the landscape—connectivity Turtle tracking research program References
Last updated: 29 August 2023 This page should be cited as: Department of Environment, Science and Innovation, Queensland (2023) Movement (ecology), WetlandInfo website, accessed 20 December 2024. Available at: https://wetlandinfo.des.qld.gov.au/wetlands/ecology/processes-systems/movement/ |
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