Evans R.D.,17 Dick Perry Avenue |
Evans R.D.,University of Western Australia |
Wilson S.K.,17 Dick Perry Avenue |
Wilson S.K.,University of Western Australia |
And 5 more authors.
Marine Biology | Year: 2014
Macroalgal fields are a feature of the shallow tropical benthos, yet their importance for coral reef fish population dynamics remains poorly understood. The abundance of fish recruits was recorded using underwater visual census at six macroalgal and 11 coral reef sites in the Montebello and Barrow Islands. Surveys identified 6,935 individual recruit fish from 105 species, 54 genera and 20 families. Of these, 1,401 recruits from 48 species, 31 genera and 14 families were observed in macroalgal sites. Sixteen of the 105 recruit species (15.2 %) were observed exclusively at macroalgal sites. Forty-two (87.5 %) of these species have been observed as adults on adjacent coral reefs. Species composition of fish recruits differed significantly between the two habitats. Corallivore, small omnivore and zooplanktivore recruits had significantly higher numbers in the coral sites, while the results clearly demonstrate that juveniles, within the genera Lethrinus and Choerodon, as well as large algal croppers, are predominantly found at macroalgal (74-100 %) rather than coral-dominated sites. High-canopy macroalgae cover was positively correlated with abundance of these taxa, particularly Lethrinids (r2 = 0.40). This study is the first to highlight the important attributes of tropical macroalgal fields and suggests that they have a similar role to seagrass meadows as essential juvenile habitat, thus warranting greater attention in conservation planning and ecological studies. © 2013 Springer-Verlag Berlin Heidelberg.
Emslie M.J.,Australian Institute of Marine Science |
Logan M.,Australian Institute of Marine Science |
Williamson D.H.,James Cook University |
Ayling A.M.,Sea Research |
And 11 more authors.
Current Biology | Year: 2015
Summary Networks of no-take marine reserves (NTMRs) are widely advocated for preserving exploited fish stocks and for conserving biodiversity. We used underwater visual surveys of coral reef fish and benthic communities to quantify the short- to medium-term (5 to 30 years) ecological effects of the establishment of NTMRs within the Great Barrier Reef Marine Park (GBRMP). The density, mean length, and biomass of principal fishery species, coral trout (Plectropomus spp., Variola spp.), were consistently greater in NTMRs than on fished reefs over both the short and medium term. However, there were no clear or consistent differences in the structure of fish or benthic assemblages, non-target fish density, fish species richness, or coral cover between NTMR and fished reefs. There was no indication that the displacement and concentration of fishing effort reduced coral trout populations on fished reefs. A severe tropical cyclone impacted many survey reefs during the study, causing similar declines in coral cover and fish density on both NTMR and fished reefs. However, coral trout biomass declined only on fished reefs after the cyclone. The GBRMP is performing as expected in terms of the protection of fished stocks and biodiversity for a developed country in which fishing is not excessive and targets a narrow range of species. NTMRs cannot protect coral reefs directly from acute regional-scale disturbance but, after a strong tropical cyclone, impacted NTMR reefs supported higher biomass of key fishery-targeted species and so should provide valuable sources of larvae to enhance population recovery and long-term persistence. © 2015 Elsevier Ltd All rights reserved.
Smith M.J.,17 Dick Perry Avenue |
Drake P.L.,17 Dick Perry Avenue |
Drake P.L.,University of Western Australia |
Vogwill R.,University of Western Australia |
McCormick C.A.,17 Dick Perry Avenue
Ecosphere | Year: 2015
Species composition and structure are important properties that can influence the extent to which people value a natural element. Hence these two properties can provide a means to directly manage natural elements to meet values-based goals. With this principle in mind, we studied soil seed bank assembly in two wetland vegetation elements recognized for their science/education, opportunity and system benefit values. Because seed banks drive the composition and structure associated with a vegetation element, which in turn influence human value satisfaction, variance partitioning modeling was used to determine which combination of filters best described patterns in the seed bank beta diversity. A combination of abiotic (soil permeability and soil salinity) and spatial filters with several interactions were the best descriptors of beta diversity, particularly for one vegetation element (wetland 1). Within the remaining vegetation element (wetland 2), a much greater diversity of weed species was observed. Based on the different patterns in diversity, including the links between these patterns, particular filters, and associated processes, we propose that the two vegetation elements, despite their close proximity to each other, are on diverging reassembly pathways. To manage the vegetation elements such that they maintain their values, we suggest hydrological processes are controlled to ensure that soil salinity does not increase dramatically. Dramatic increases in salinity will decrease element value by reducing vegetation diversity and plant community structure. We also stress the importance of understanding and managing processes that effect within-element dispersal and invasion by weeds. Here we demonstrate a general approach to inform the management of natural resources. It is important to identify, understand, and manage the filters (and associated processes) that restrict observable patterns in the properties that influence element value, sensu rules to manage the human valuation of natural elements. © 2015 Smith et al.