Differences in the distributions of freshwater fishes and decapod crustaceans in urban and forested streams in Auckland, New Zealand

Abstract

Using data from existing studies, assem blages of freshwater fishes and decapod crustaceans were examined at 39 sites in urbanised catchments and 57 sites in forested (reference) catchments within the greater Auckland region, New Zealand. Eleven native and 1 exotic fish species and 2 native decapod crustacean species were recorded. Species richness and fish index of biotic integrity (ibi) scores were lower overall in streams in urbanised catchments. Shortfin eel (Anguilla australis) and mosquitofish (Gambusia affinis) were more dominant in urban streams; all other commonly occurring species were found significantly more often in reference streams. Nondiadromous native species (cran's bully (Gobiomorphus basalis) and freshwater crayfish (Paranephrops planifrons)) were absent from urban streams, but relatively abundant in reference streams. This absence of nondiadromous species, together with the urban occurrence of five diadromous species suggests that migratory barriers pose less of a threat to freshwater communities than physicochemical disturbance in streams in the Auckland urban region.

Stream or discharge? Analysing hydrosocial relations in the Waimapihi Stream to innovate urban water politics

“…The inhabitants of the p a regarded the Waimapihi Stream as a sacred waterway; it was an important mahinga kai site and a source of water for drinking and irrigation of k umara and flax cultivations (Waitangi Tribunal, 2003). From observations of native fish present in similar streams, the Waimapihi could plausibly have had greater abundance than the contemporary state of aquatic fauna, including inanga and toitoi in addition to the banded k okopu, k oaro and k oura that currently inhabit the Waimapihi (McEwan & Joy, 2009).…”

Evaluating the effectiveness of freshwater fishes as bio-indicators for urban impacts in the Crocodile (West) catchment, South Africa

“…To obtain the upstream land cover classes surrounding each river, a 1 km buffer was placed around them. To assign each river study site an urban category, a standardised rule was formulated, following McEwan and Joy (2009). The rule classified sites with less than 10%, between 10% and 60%, and greater than 60% upstream urban land covers to be rural, peri-urban and urban, respectively.…”

Stream or Discharge: Using the Hydrosocial Cycle to Explore the Meanings of the Waimapihi Stream in Te Whanganui-a-Tara-Wellington, Aotearoa-New Zealand

“…Providing a diverse range of habitats to support multiple species is important to improve the ecology of the stream, and can include introducing boulders, woody debris, and riparian planting (Neale and Moffett, 2016). During spotlighting in the headwaters, we saw two species of freshwater fish and one decapod, seeing this few species is indicative of what McEwan and Joy (2009) found, that species richness is lower in urbanised streams than forested streams in Aotearoa-New Zealand. However, stream biodiversity is not just about fish, it is the complex interactions between multiple species in stream ecosystems (Paul and Meyer, 2001).…”

“…Contaminants in stormwater that enters the pipes, such as heavy metals and hydrocarbons, have health impacts for the fish, reducing their ability to pass safely through the pipe to the headwaters (McEwan and Joy, 2009). Phill demonstrated the importance of considering the water within the pipe when he suggested that it should be considered as the habitat of the fish.…”

“…Understanding the past intersecting processes occurring in the stream signals some of the processes happening both now and into the future, and how they influence perceptions of the Waimapihi and its place in the city. This is important as most of Aotearoa-New Zealand's major cities are coastal and stream burial is not unique to Te Whanganui-a-Tara-Wellington, consequently, coastal streams are threatened ecosystems (McEwan and Joy, 2009). Furthermore, the modification of these streams has reduced their resilience to heavy rainfall events, leaving Te Whanganui-a-Tara-Wellington, and other cities, increasingly vulnerable to flooding (McConchie, et al, 2000).…”