Spatial, temporal and ontogenetic variation in the association of fishes (family Labridae) with rocky-reef habitats

Habitat variability is an important factor structuring fish assemblages of rocky reefs in temperate Australia. Accepting the generality of this model requires that habitat-related variation is consistent through time, across multiple spatial scales, and applies to all life-history stages. We used repeated underwater visual surveys at multiple spatial scales over a 22-month period to test whether three distinct rocky-reef habitats had different wrasse assemblages and whether these assemblages were subject to spatial, temporal and ontogenetic variability. Overall, the strongest and most consistent habitat association was with sponge gardens, which had the most distinct assemblage, and the greatest species richness and density of individuals. Habitat associations in fringe and barrens were less consistent. A substantial increase in the abundance of small individuals, coinciding with warmer sea temperatures, contributed to temporal fluctuations in the density of wrasses. Overall, habitats were not strongly partitioned among larger individuals of the most abundant species, suggesting that adults are largely habitat generalists whereas small, recruiting individuals showed greater habitat specialisation. The present study emphasises the importance of incorporating spatial, temporal and ontogenetic variability into surveys of fish assemblages to understand more fully the dynamics of temperate rocky-reef systems. © CSIRO 2011

Changes in rocky reef fish assemblages throughout an estuary with a restricted inlet

Rocky reef habitat is common in many estuaries, yet its role as a habitat for fishes is poorly understood. There is also limited understanding of how access of coastal species into estuaries and habitat quality can affect the distribution of rocky reef fishes within estuaries. This study used baited remote underwater video stations to determine spatial patterns in fish assemblages associated with rocky reef habitat throughout a barrier estuary with a permanently open but restricted inlet. Estuarine rocky reefs provided habitat for a diverse assemblage of fishes, many of which were large juveniles and subadults. In the absence of a pronounced salinity or temperature gradient, a clear transition in fish assemblages occurred from coastal waters, through the inlet channel, to the central estuary, and into the inner estuary. The inlet channel, notably its narrowness and length, limits tidal input into this estuary, which acts as a significant impediment to the dispersal of many coastal fishes, and insufficient habitat excludes many coastal rocky reef species from the inner estuary. This study highlights the need to recognise estuarine rocky reefs as providing habitat for diverse fish assemblages and the role inlets play in restricting access of coastal species. © 2013 Springer Science+Business Media Dordrecht

Impacts of docks on seagrass and effects of management practices to ameliorate these impacts

© 2013 Elsevier Ltd. Seagrasses have high conservation and human-use values, but around the world they are being damaged by human activities. Compared to the larger spatial scale at which some human activities affect estuaries and their seagrasses (e.g. catchment disturbance, dredging, pollution, trawling), recreational boating and infrastructure of moorings and docks act at smaller scales. However, the cumulative effects contribute to stresses acting on seagrass beds. This study assessed the effects of docks on the native seagrass Zostera muelleri subsp. capricorni in an estuary in south-east Australia and of current management practices designed to reduce dock impacts on this seagrass. A field survey found that seagrass biomass was significantly reduced below docks, and the effects were not influenced by dock orientation. Management practices requiring the use of a mesh decking to provide greater light penetration reduced, but did not eliminate, the reduction in seagrass biomass caused by docks. A modified beyond BACI experiment provided evidence for a causal link between the installation of wooden or mesh docks and reductions in biomass of seagrass. The reduction in biomass was apparent 6 mo after dock installation, and by 26 mo seagrass biomass had declined by at least 90%. Faced with increasing coastal populations, increases in recreational use, and continued pressures from other human activities, alternative management practices that further minimize the effects of docks are needed

Methods of social assessment in Marine Protected Area planning: Is public participation enough?

Addressing social and economic considerations is crucial to the success of Marine Protected Area (MPA) planning and management. Ineffective social assessment can alienate local communities and undermine the success of existing and future MPAs. It is rare to critique the success of methods used currently to incorporate social and economic considerations into MPA planning. Three Australian MPA planning processes covering three states and incorporating federal and state jurisdictions are reviewed in order to determine how potential social impacts were assessed and considered. These case studies indicate that Social Impact Assessment (SIA) is under-developed in Australian MPA planning. Assessments rely heavily on public participation and economic modelling as surrogates for dedicated SIA and are followed commonly by attitudinal surveys to gauge public opinion on the MPA after its establishment. The emergence of issues around public perception of the value of MPAs indicates the failure of some of these proposals to adequately consider social factors in planning and management. This perception may have potential implications for the long term success of individual MPAs. It may also compromise Australia's ability to meet international commitments for MPA targets to gazette at least 10% of all its marine habitats as MPAs. Indeed, this is demonstrated in two of the three case studies where social and economic arguments against MPAs have been used to delay or block the future expansion of the MPA network. © 2011 Elsevier Ltd

Application of baited remote underwater video stations to assess benthic coverage in the Persian Gulf

© 2015 Elsevier Ltd. A baited remote underwater video station (BRUVS) is generally considered an appropriate sampling tool for fish. The applicability of BRUVS to determine the substrate coverage was assessed by comparing stills from BRUVS videos to traditional point intercept transect (PIT) data to estimate percentage cover (PC) of different benthic substrate categories. Mean PCs of hard corals, rock, sand, and coral growth forms yielded statistically identical values with the two survey methods, while PCs of motile epibenthic invertebrates were underestimated by BRUVS in areas of both high and moderate relief. Yet, multivariate analyses revealed that the two methods yield similar substrate assemblage in an area of moderate relief. Results of our study suggest that the BRUVS can be effectively used to quantify both the presence/absence of a basic set of benthic habitat characteristics and diversity of coral growth forms on coral reefs in the Persian Gulf

Animal v. plant-based bait: Does the bait type affect census of fish assemblages and trophic groups by baited remote underwater video (BRUV) systems?

© 2016 The Fisheries Society of the British Isles. Coral reef fish communities were sampled at the Nayband Marine Park, Iran, using baited remote underwater video stations (BRUVSs) which incorporated animal (i.e. frigate tuna Auxis thazard and beef liver), or plant-based baits (i.e. raw dough and raw dough-turmeric powder mix). The A. thazard was found to record significantly (P < 0·05) higher species richness and number of carnivorous fishes than plant-based baits, while abundance of herbivores was maximum in raw dough-turmeric powder mix trials. There was also a significant difference in trophic composition of fish assemblages surveyed by animal- and plant-based baits which seemed to be due to variations in attraction patterns of carnivores and herbivores occurring at the earlier phases of each BRUV deployments. Meanwhile, the assemblage structure was comparable among fish assemblages sampled by different bait treatments, indicating that species-level responses to each bait type may be more complicated. In essence, the efficiency of mixed baits should also be examined in future studies

Coral reef fish assemblages along a disturbance gradient in the northern Persian Gulf: A seasonal perspective

© 2015 Elsevier Ltd. Seasonal dynamics of coral reef fish assemblages were assessed along a gradient of potential anthropogenic disturbance in the Northern Persian Gulf. Overall, the attributes of coral reef fish assemblages showed seasonality at two different levels: seasonal changes irrespective of the magnitude of disturbance level (e.g. species richness), and seasonal changes in response to disturbance level (e.g. total abundance and assemblage composition). The examined parameters mostly belonged to the second group, but the interpretation of the relationship between patterns of seasonal changes and the disturbance level was not straightforward. The abundance of carnivorous fishes did not vary among seasons. SIMPER identified the family Nemipteridae as the major contributor to the observed spatiotemporal variations in the composition of coral reef fish assemblages in the study area

Strong Enhancement of Superconducting Correlation in a Two-Component Fermion Gas

We study high-density electron-hole (e-h) systems with the electron density slightly larger than the hole density. We find a new superconducting phase, in which the excess electrons form Cooper pairs moving in an e-h BCS phase. The coexistence of the e-h and e-e orders is possible because e and h have opposite charges, whereas analogous phases are impossible in the case of two fermion species that have the same charge or are neutral. Most strikingly, the e-h order enhances the superconducting e-h order parameter by more than one order of magnitude as compared with that given by the BCS formula, for the same value of the effective e-e attractive potential \lambda^{ee}. This new phase should be observable in an e-h system created by photoexcitation in doped semiconductors at low temperatures.Comment: 5 pages including 5 PostScript figure