Artificial waterway design affects fish assemblages in urban estuaries

Abstract

Fishes were collected from residential canal estates leading directly off natural estuaries and artificial lakes with control tidal exchange in south-east Queensland, Australia, to test the model that the difference in artificial waterway design affects fish assemblages. A total of 17 779 fish representing 52 species was caught, including 23 species of economic importance (45% of the catch). Total fish abundance and species richness differed little among sites within or between the two artificial habitats (canals and lakes) in either of the seasons sampled (winter and spring). Multivariate analysis showed, however, that assemblages differed among sites within the same artificial habitat. The differences were best explained by the distance sites were from open water, while salinity, water temperature and dissolved oxygen explained little of the variability. Most species were found in canals and lakes, but there were enough differences in composition between the habitats to detect a difference in both seasons (significant ANOSIM tests). Salinity was lower in lakes because of the tidal restrictions, and while this was only weakly correlated with differences in fish assemblages, it had the most explanatory power of any environmental variable. New recruits arrived later in lakes than canals, perhaps because of the barriers to tidal flow. A survey the following year showed that differences among individual lakes were consistent through time, offering insights into the influence of different tidal barriers on fish assemblages. The design change from canals to lakes has a minor influence on fish assemblages and alters the timing of recruitment.

Natural or Artificial? Habitat-Use by the Bull Shark, Carcharhinus leucas

“…In the GCS, the differences in use of natural and artificial habitats by bull sharks was likely influenced by the spatial and temporal variation in the physical and hydrological characteristics of the river and the adjoining canals [23], [60], [57]. While the species composition of the estuarine fish community in the canals mirrors that found in the river [61], there are often lower abundances of prey and small fish mainly associate with artificial structures, e.g. jetty pilings for refuge rather than food [93] and this may affect predatory search images [94] and reduce movements into the canals.…”

Estuarine canal estate waters: Hotspots of CO2 outgassing driven by enhanced groundwater discharge?

“…1). Australia has the largest expanse of canal systems worldwide with approximately 440 linear km of artificial urban waterways and canal estate construction with 90% of residential canal estates in the broader Gold Coast region (Waltham and Connolly, 2007). In total there are~300 km of canals in the study area (Waltham and Connolly, 2011).…”

“…In total there are~300 km of canals in the study area (Waltham and Connolly, 2011). The artificial canals provide habitat to aquatic organisms, drainage of stormwater and flood mitigation (Waltham and Connolly, 2007).…”

Canal estate development in an acid sulfate soil—Implications for human metal exposure

“…Australia has the greatest expanse of residential canal estates in the world, with around 440 km of urban waterways (Waltham and Connolly, 2007). According to Stein et al (2002), almost all Russell and Helmke, 2002;Stephens and Ingram, 2006;White et al, 2006).…”