Thea Linke

This study has explored the extent to which the predominant faunal component of the diet (benthic macroinvertebrates) of the large, long-lived estuarine-resident Acanthopagrus butcheri is related to particular prey and predator traits. Focus is placed on the location (infaunal vs epifaunal) and species size category (small vs medium vs large) of the prey and feeding behaviour of A. butcheri. Data on the benthic macroinvertebrates in the stomach contents of A. butcheri in a microtidal estuary (Swan-Canning, Western Australia) are compared with those of macroinvertebrates sampled in the benthos at the same sites and times in eight consecutive seasons using an Ekman grab. The eight most abundant small macroinvertebrate species in the benthic samples were infaunal and, apart from the bivalve Arthritica semen that was ingested by only a few fish, were not fed on by A. butcheri. In contrast, the three most abundant medium and large-sized species in the benthos, the epifaunal bivalves Xenostrobus securis and Fluviolanatus subtortus and infaunal nereidid polychaete Simplisetia aequisetis, were preyed on substantially, with the first ingested by 54% of A. butcheri and contributing over 51% to dietary volume. Although the eunicid polychaete Marphysa sanguinea occurred in only 7% of benthic samples and contributed <0.1% to abundance, this large infaunal species ranked second in contribution to dietary volume (12%). This species and S. aequisetis were preyed on when they emerged in part or wholly above the substrata. The above results imply that, in terms of prey, A. butcheri selects predominantly medium and large epifaunal macroinvertebrate species and those medium to large infaunal polychaetes which, at times, move out of the substrata. This reflects non-emergent infauna being present in essentially all benthic samples and contributing 66% to total abundance, whereas this group was found in only 8% of stomach samples of A. butcheri and contributed only 2% to dietary volume. In contrast, emergent infauna and epifauna contributed 12 and 22%, respectively, to abundance in the benthos, but as much as 22 and 75%, respectively, to the diets of A. butcheri. It is concluded that the marked selectivity of A. butcheri for prey was related to certain prey and predator traits, i.e. size category of prey species, and prey located above the substrata, either permanently or at frequent intervals, and to visual acuity and a fast-swimming angled attack by the predator.

Expectations and patterns of publication have changed markedly with evolving online availability and associated development of new citation gathering databases. Perhaps the most vulnerable components of the scientific literature to ongoing change are books and book chapters, given their elongated publication timelines and generally more limited online availability. To test this, we applied citation analyses and assessments of library holdings to determine the use of the natural history books published by Surrey Beatty & Sons between 1987 and 2010. We (i) evaluated the relative use of book chapters and journal papers by comparing citations to chapters in the five books of the Nature Conservation series by Surrey Beatty & Sons to citations of journal chapters in four Australian journals published in the same years, (ii) determined the efficacy of four different databases in retrieving citations to book chapters by comparing their recovery of citations to the five books of the Nature Conservation series, and (iii) quantified noncitation measures related to library holdings to evaluate the use of the books on the entire Surrey Beatty & Sons list. Mean citations/chapter to the first three books in the Nature Conservation series were similar to the mean citations/paper in four Australian journals published in the same years. However, the mean citations/chapter of the last two books declined relative to citations/paper for the journals, suggesting a fall in book use evident by early this century. Citation retrieval varied across databases; Google Scholar retrieved most citations, followed by Scopus, Web of Science (Cited Reference Search) and Web of Knowledge. Contrary to published concerns, no citations retrieved by Google Scholar were in questionable sources such as contents pages - many were from highly ranked journals. Each book in the full Surrey Beatty & Sons list was held by an average of 45.3 libraries in Australia and 36.1 in the USA, and less than five in each of the UK, New Zealand, Hong Kong, Canada, Germany and South Africa. This was a similar coverage to another Australian publisher, the Royal Zoological Society of New South Wales, and indicated strong markets in Australia and the USA. It was less, though, than the number of libraries with current or past subscriptions to five Australian journals publishing nature conservation content. We conclude that citation data for books and book chapters are available and that library holdings provide another measure of use. The online ‘visibility’ of books may be a problem, but can be improved through better marketing and improved author search techniques.

Six abundant fish species were collected from a large embayment during both day and night and at bimonthly intervals for a year. Gerres subfasciatus and Upeneus tragula occurred mainly over bare sand, while Psammoperca waigiensis, Centrogenys vaigiensis and Apogon victoriae lived mainly in seagrass (Amphibolis antarctica) and A. rueppellii often migrated from seagrass to over bare sand at night. All species except U. tragula fed at night, as well as during the day. The overall dietary compositions of the six species were significantly different from each other, even when the species occurred in the same habitat. G. subfasciatus and U. tragula consumed greater volumes of errant polychaetes, which could be readily targeted in a substrate that does not contain dense rhizome mats. In contrast, P. waigiensis, C. vaigiensis and A. victoriae ingested greater volumes of carid decapods, which are particularly abundant in seagrass and, thus, within the water column. Furthermore, when A. rueppellii moved at night from seagrass to over sand, the consumption of carid decapods declined, whereas that of polychaetes and particularly mysids, which are very abundant over bare sand, increased. However, the composition of the prey consumed by different species within the same habitat also often varied markedly. For example, unlike U. tragula, G. subfasciatus ingested not only sedentary polychaetes, but also considerable volumes of errant polychaetes, reflecting its ability to use a combination of vision and its highly protrusible mouth to target prey both on and just below the substrate surface. Differences in the types and range of prey ingested by the six species could often be related to differences in the overall size, width and/or protrusibility of the mouth. Furthermore, dietary breadth was greatest in species with the largest mouth dimensions. The diets of three species underwent diel changes that could be related to differences in foraging mode and/or prey availability. Thus, a use of vision to detect prey would account for the greater consumption during the day of copepods by G. subfasciatus and of small teleosts by A. rueppellii, while the nocturnal emergence of amphipods and/or tanaids from the substrate explains their greater ingestion by G. subfasciatus, A. victoriae and A. rueppellii at night. Although the smaller individuals of each species consumed larger volumes of prey, such as copepods and mysids, and the larger fish ingested greater volumes of prey, such as decapods and teleosts, the extent of the size-related changes in diet varied markedly amongst species.