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Ecosystem engineers often exert strong effects on the recruitment of other species through modification of the local abiotic and biotic environment. In 2015, artificial reefs in eastern Tasmania (− 42.64693, 148.01481) spanning seven different patch sizes (0.12–7.68 m2) and supporting four densities of transplanted kelp (Ecklonia radiata at 0, 4.1, 8.2 and 16.4 kelp m−2) were used to determine how the patch size and density of this ecosystem engineer influenced the recruitment of microphytobenthic (MPB) algae, and a secondary ecosystem engineer, the mussel Mytilus galloprovincialis. Increasing kelp density and patch size inhibited the establishment of subcanopy MPB algae on settlement slides and reduced the recruitment of mussels in standardised rope fibre habitats (RFHs). The productivity:biomass ratio (P:B) of mussel recruits tended to be lower on small reefs and reefs without kelp, relative to larger reefs with high densities of kelp. Canopy shading and reduced cover of turf algae appeared to negatively impact the recruitment of MPB algae and mussels, whilst reduced sediment accumulation on the reefs due to the kelp was also negatively associated with mussel recruitment. These findings highlight the role of ecosystem engineering by kelp in inhibiting the establishment of other species which may additionally impact community dynamics and primary and secondary productivity. The limited capacity of small kelp patches to inhibit the recruitment of other organisms supports the notion that fragmented patches of ecosystem engineers could be more suspectable to adverse outcomes from species interactions making them less resistant to shifts towards an alternative ecosystem state. [ABSTRACT FROM AUTHOR]

Patterns of abundance and shell morphology of intertidal gastropods are typically thought to depend on environmental conditions, but ecosystem engineers such as canopy-forming seaweeds can also influence these traits. The intertidal seaweed Hormosira banksii (H. banksii) is an abundant species and important ecosystem engineer on rocky shores and estuaries in south-east Australia, where it creates thick canopies colonized by a range of invertebrates, particularly gastropods. In Tasmania (southern Australia), H. banksii shows large variability in thallus length and structure, with different algal morphologies on coasts and in estuaries. In this study, individuals of two gastropod species were sampled from different habitats (north coast, east coast and northern estuaries) to: (1) describe the spatial variability in their abundance and shell morphology, and (2) understand if any relationship exists between H. banksii morphology and gastropod shell morphology. Gastropod abundance and morphology were variable, but multivariate analysis suggested a marginal influence of H. banksii morphological traits, particularly vesicle size, on the patterns observed. As the two gastropod species use habitat differently and that different H. banksii morphs occur in different locations, our results suggest that both algal morphology and environmental conditions may affect gastropod abundance and shell morphology across the different habitats. Hence, from these results a model can be developed and tested in subsequent experimental work to tease apart the effects of seaweed morphology from environmental conditions. [ABSTRACT FROM AUTHOR]

Seasonal variation in catchability of legal-sized male and female southern rock lobster Jasus edwardsii in a scientific reserve in south-east Tasmania, Australia, over a 15-month period was described by modelling the effects of water temperature, moulting and mating. Seasonal changes in water temperature described 62% of the variation of catchability for males, but were a poor predictor of catchability for females outside winter. Both moulting and mating was highly synchronised, although males and females moulted at different times of the year. This had a significant sex-specific effect on catchability, because the models developed here indicate that feeding and therefore catchability is decreased during moulting and mating and followed by an increased food consumption to compensate for the lack of feeding during these periods. Gaussian probability density functions were used to represent the timing and intensity of moulting, mating and subsequent compensation periods, and were combined with the description of seasonal temperature changes. Four Gaussian functions in agreement with independent biological data considerably improved the model fits for the catchability of males (R2=0.84). Adding a single Gaussian function to the temperature model, representing a combined moulting and mating period, provided a good fit to the variation in catchability of females (R2=0.90). However, the biological relevance of this model remained unclear during a second period of moulting and mating where empirical observations were missing. [ABSTRACT FROM AUTHOR]

It is widely believed that, when extrinsic conditions are similar, the likelihood of species invading established assemblages decreases with increasing species richness of the recipient community. Here we show that, for a sessile marine invertebrate community, invasion of patches increases with richness of the patch. We show that invasions can increase with local species richness by two distinct mechanisms. In the first, opportunistic colonisers with traits typical of invasive species colonise species-rich patches at higher rates because speciose patches are dominated by small colonies and mortality rates of small colonies are greater than that of large ones. Thus, mortality provides bare space for opportunists to colonise more frequently in species-rich patches. In the second, some species avoid colonising open areas of free space but preferentially associate with established colonies of particular other species, and a given preferred associate is more likely to occur in species-rich than in species-poor patches. These patterns are the result of particular properties of individual species and local species dynamics, and show that reduced risk of invasion is not necessarily an intrinsic property of species-rich communities. We conclude that resistance to invasion will be determined by the properties of the particular component species and emergent dynamics of the recipient community, and not by an aggregate community property such as richness. [ABSTRACT FROM AUTHOR]

Background. The number of American students pursuing advanced science degree continues to wane. Summer research experience programs are ideal mechanisms to introduce high school and college students to scientific lifestyles. Methods. A follow-up of participants from 1995-2003 was conducted to gauge student perception of the program and to measure outcomes. Results. Data are presented from the responses of 287 (81%) participants. The Program was successful in recruiting female (67%) and underrepresented (>35%) students. Very high percentages of trainees reported pursuing advanced scientific study (>85% of high school and>92% college students). Conclusions. Summer research experiential programs can be successful in initiating or maintaining a student's interest in science careers. [ABSTRACT FROM AUTHOR]