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Narrandera, Australia

Stoffels R.J.,CSIRO | Stoffels R.J.,La Trobe University | Rehwinkel R.A.,New South Wales Fisheries | Price A.E.,La Trobe University | Fagan W.F.,University of Maryland University College
Aquatic Sciences | Year: 2016

In river-floodplain ecosystems, overbank flows interact with floodplain geomorphology to generate a network of transient inter-waterbody connections. Heterogeneity in the characteristics of these connections may interact with species-specific dispersal capacity to affect the maintenance of diversity and community assembly on the floodplain. We modelled the immigration and emigration rates of nine species of fish entering and leaving a large floodplain lake during a hydrological connection with the parent river. Dispersal rates were modelled as a continuous function of time-since-connection over 3 months, with the aim of testing for species-specific patterns in (a) the timing and magnitudes of lateral dispersal, and (b) the balance between total immigration into, and emigration from, the lake. Significant interspecific variation in the timing and magnitude of lateral dispersal was evident. Magnitude of lateral dispersal was not a function of local abundance for all species. Further, the balance between immigration to, and emigration from, the lake varied significantly across species, and over time within species. The immigration–emigration balance of a species was not related to its magnitude of lateral dispersal, but may be related to its behavioural and life-history traits. Spatial heterogeneity in the duration of inter-waterbody connections may interact with species-specific dispersal functions to shape assembly of floodplain communities. Accordingly, habitat heterogeneity among floodplain waterbodies is not strictly necessary for heterogeneity in fish community composition. These dynamics have implications for the maintenance of diversity in river-floodplain fish metacommunities under both natural and managed connectivity regimes. © 2015, Springer Basel. Source


Kelaher B.P.,Southern Cross University of Australia | Page A.,New South Wales Fisheries | Dasey M.,New South Wales Fisheries | Maguire D.,New South Wales Fisheries | And 4 more authors.
Global Ecology and Conservation | Year: 2015

Marine sanctuaries are areas where the extraction of biota is not permitted. Although most marine sanctuaries have a positive influence on biotic communities, not all sanctuaries are meeting their conservation objectives. Amidst possible explanations (e.g., size, age and isolation), insufficient enforcement is often speculated to be a key driver of marine sanctuary underperformance. Despite this, there are few studies directly linking quantitative enforcement data to changes in biotic communities within marine sanctuaries. Here, we used an asymmetrical-BACI experimental design from 2006-2012 to test whether new enforcement initiatives enhanced abundances of target fishes and threatened species in an existing large sub-tropical marine sanctuary relative to areas open to fishing. Implementation of the new enforcement initiatives in 2010 was associated with a 201% increase in annual fine rate and a significant increase in target fish and elasmobranch abundance, as well as sightings of a critically-endangered shark, in the marine sanctuary relative to areas open to fishing. Overall, these results demonstrate that strengthening enforcement can have a rapid positive influence on target fish and perhaps threatened species in a subtropical marine sanctuary. From this, we contend that increased enforcement guided by risk-based compliance planning and operations may be a useful first step for improving underperforming marine sanctuaries. © 2015 The Authors. Source

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