During recent decades, the Tuckahoe Creek (Virginia) watershed has been altered by human activities, including road and bridge construction, commercial and residential development, and riparian losses. We used historical (1958) and recent (1990) data to evaluate the hypothesis that long‐term, low‐intensity urbanization affects a warmwater stream fish assemblage in ways usually attributed to acute, high‐intensity perturbations. In 1990, fish species diversity of Tuckahoe Creek was significantly lower (P < 0.05) than it had been in 1958, and abundance was substantially lower for all species and trophic guilds. Four cyprinids, one ictalurid, and one percid present in 1958 were not collected in 1990. Jaccardˈs community similarity coefficient (species composition by site between 1958 and 1990) was negatively correlated with near‐stream development of the watershed at six study sites (r = –0.84; P < 0.05). Some characteristics of the feeding ecology of selected fish species, including consumption of terrestrial prey and diet overlap, exhibited slight differences between 1958 and 1990. Observed changes in the fish assemblage were consistent with our hypothesis. Our findings also suggest that the lack of invasions by exotic fishes may not always indicate undisturbed stream conditions.

Environmental and anthropogenic influences on spatiotemporal dynamics of Alosa in Chesapeake Bay tributaries.

&lt;p&gt;The intensification of dairy farming on the agricultural landscape in New Zealand has raised concerns about pollution sources from dairy faecal runoff into waterways. The transport of faecal pollution from farms into waterways is facilitated by overland flow, which can result from rain and flood events, poorly designed irrigation practices and the washing down of milking sheds.&lt;/p&gt;&lt;p&gt;An important step for mitigation of pollution is the identification of the source(s) of faecal contamination. When elevated levels of faecal indicator bacteria (FIB) such as &lt;em&gt;Escherichia coli &lt;/em&gt;are identified in a waterway, faecal source tracking (FST) tools such as microbial source tracking (MST) using quantitative polymerase chain reaction (qPCR), and faecal steroids (for example, cholesterol) provide information about the sources of faecal contamination. The understanding of the fate (degradation/persistence) and transport of these FST markers in the environment is recognised as an important requirement for the interpretation of water quality monitoring in aquatic environments.&lt;/p&gt;&lt;p&gt;This study investigated the effects of faecal decomposition on bovine faecal indicators (&lt;em&gt;E. coli &lt;/em&gt;and FST markers: bovine-associated qPCR markers and ten faecal steroids) by monitoring the effect of flood and rainfall events on simulated cowpats over a five and a half month period under field conditions. Two separate spring/summer trials were conducted to evaluate: Trial 1) the mobilisation under simulated flood conditions of the faecal indicators from irrigated versus non-irrigated cowpats, Trial 2) the mobilisation of faecal indicators from non-irrigated cowpat flood runoff versus runoff after simulated rainfall onto non-irrigated cowpats.&lt;/p&gt;&lt;p&gt;The microbial community changes within the decomposing cowpat (as illustrated by amplicon-based metagenomic analysis) were expected to impact on the survival/persistence of the bacterial targets of the MST markers, and also alter the ratio between faecal sterols and their biodegradation products, the stanols. It was hypothesised, therefore, that there would be:&lt;/p&gt;&lt;ul&gt;&lt;li&gt;Changes over time in the concentration of&lt;em&gt; E. coli &lt;/em&gt;and the bovine-associated MST markers mobilised into the cowpat runoff&lt;/li&gt; &lt;li&gt;Alterations in the FST ratio signature of the ten measured faecal steroids, resulting in a change from a bovine faecal steroid signature in fresh cowpat runoff to other animal faecal signatures in the runoff from decomposing cowpats&lt;/li&gt; &lt;li&gt;A difference in the mobilisation decline rates of all FST and microbial markers within a treatment regime and between treatments.&lt;/li&gt; &lt;/ul&gt;&lt;p&gt;Linear regression analysis was undertaken to establish mobilisation decline rates for each of the analytes in the mobilisable phase from the cowpat runoff treatments, with calculation of the time taken in days for reduction in 90% of the concentration (T&lt;sub&gt;90&lt;/sub&gt;), and statistical comparison of the regression coefficients (slopes) of all analytes. The results will include a discussion of the impacts of the study&amp;#8217;s observations on the interpretation of faecal indicator assessments for water quality monitoring in waterways influenced by sources of faecal contamination.&lt;/p&gt;