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In the high seas, regional fishery management organisations are required to implement measures to prevent significant adverse impacts on vulnerable marine ecosystems (VMEs). Our objectives were to develop habitat suitability models for use in the spatial management of bottom fisheries in the South Pacific and to evaluate these and existing models using independent data from high‐quality seafloor imagery. Presence‐only models for seven VME indictor taxa were developed to complement previous modelling. Evaluation of habitat suitability models using withheld data indicated high mean True Skill Statistic scores of 0.44–0.64. Most habitat suitability models performed adequately when assessed with independent data on taxon presence and absence but were poor surrogates for abundance. We therefore advocate caution when using presence‐only models for spatial management and call for more systematically collected data to develop abundance models. [ABSTRACT FROM AUTHOR]

Abstract: Macrocystis pyrifera (L.) C. Agardh provides biogenic habitat for species of significant commercial, cultural and recreational value; however, the floating surface canopies of M. pyrifera are particularly vulnerable to physical and biological disturbance (e.g., herbivory, storm events and harvesting). Given the key ecological roles of M. pyrifera, it is important to identify the impacts of photosynthetic tissue loss on growth and reproduction. I hypothesized that canopy removal would result in compensatory regeneration of the surface canopy. As life history theory posits a tradeoff between growth and reproduction, I also hypothesized that canopy removal would involve a reduction in reproductive investment, as either: (i) reduced production of reproductive structures; or (ii) changes in reproductive condition from fertile to sterile. To evaluate these hypothesizes I conducted two field experiments. In the first experiment, there was no significant difference in the generation of vegetative fronds or reproductive blades between controls (no loss of photosynthetic tissue from surface canopies) and treatments where photosynthetic tissue in surface canopies was thinned by either 30% or 70%. Relative to controls, the removal of entire surface canopies to a depth of 1.2m (i.e., simulated commercial harvesting) did not affect the generation of new vegetative fronds; however, the generation of reproductive blades was reduced by an average of 86%, suggesting that without the organic production supplied by the canopy, reproduction, but not growth, suffers. Further, the lack of evidence for compensatory growth despite reductions in reproduction suggests that M. pyrifera has little tolerance to canopy loss. The second experiment, which examined the effect of removing surface canopies on rate and longevity of changes in reproductive condition, found that although no control algae became sterile, 89% of algae with their surface canopies removed became sterile 50d after canopy removal, with effects persisting for up to 83d. As the supply of M. pyrifera propagules in the center of kelp forests can be tightly coupled to local reproductive output, induced sterility via the loss of photosynthetic tissue could affect the long-term stability of M. pyrifera beds. Further investigation into the scalability of these results and implications for long-term stability of M. pyrifera beds is warranted. [Copyright &y& Elsevier]

The article discusses research done on the impact of heterospecifics and structural refuge on the survival of the coral reef fish Thalassoma (T.) hardwicke collected in Moorea, French Polynesia. The quantification of the habitat association for juvenile T. hardwicke and several sympatric labroid species was conducted using surveys. The identification of the impact of the sympatric labroid species on the survival of focal individuals was done using a field assay. Information on the establishment of social dominance hierarchies between T. quinquevittatum and T. hardwicke is also presented.

Many communities experience repeated periods of colonization due to seasonally regenerating habitats or pulsed arrival of young-of-year. When an individual's persistence in a community depends upon the strength of competitive interactions, changes in the timing of arrival relative to the arrival of a competitor can modify competitive strength and, ultimately, establishment in the community. We investigated whether the strength of intracohort competitive interactions between recent settlers of the reef fishes Thalassonia hardwicke and T. quinquevittatum are dependent on the sequence and temporal separation of their arrival into communities. To achieve this, we manipulated the sequence and timing of arrival of each species onto experimental patch reefs by simulating settlement pulses and monitoring survival and aggressive interactions. Both species survived best in the absence of competitors, but when competitors were present, they did best when they arrived at the same time. Survival declined as each species entered the community progressively later than its competitor and as aggression by its competitor increased. Intraspecific effects of resident T. hardwicke were similar to interspecific effects. This study shows that the strength of competition depends not only on the identity of competitors, but also on the sequence and timing of their interactions, suggesting that when examining interaction strengths, it is important to identify temporal variability in the direction and magnitude of their effects. Furthermore, our findings provide empirical evidence for the importance of competitive lotteries in the maintenance of species diversity in demographically open marine systems. [ABSTRACT FROM AUTHOR]