The loss of seagrasses in Cockburn Sound, Western Australia. I. The time course and magnitude of seagrass decline in relation to industrial development

The areas of seagrass meadows in Cockburn Sound, a marine embayment in Western Australia, were estimated from historical aerial photographs supplemented by ground surveys, studies on meadows in adjoining areas, and coring for rhizome remains. Ten species of seagrasses with different habitat tolerances are recorded for the area, with Posidonia sinuosa Cambridge et Kuo forming the most extensive meadows. It is estimated that from 1954 to 1978 the meadow area was reduced from some 4200 to 900 ha. Based on measurements of aboveground productivity at several sites, this represents a reduction of leaf detritus production from 23 000 to 4000 t (dry wt.) y⁻¹. The major loss of seagrass occurred during a period of industrial development on the shore, and the discharge of effluents rich in plant nutrients.     

Seagrass Transplanting in Cockburn Sound, Western Australia: A Comparison of Manual Transplantation Methodology Using Posidonia sinuosa Cambridge et Kuo

Seagrass transplants (plant units [PUs]) were established to examine the feasibility of seagrass rehabilitation in Cockburn Sound, Western Australia. Five hundred and twenty plant units (plugs and sprigs) of Posidonia sinuosa Cambridge et Kuo were placed at seven locations at depths of 3, 5, and 9 m and monitored to determine the influence of transplant method, location, and depth upon survival and growth over 2 years. Depending on the site, more plugs had survived at the completion of the trial (mean survival 41%) than sprigs (mean survival 15%). Plug and sprig survival differed significantly with transplant depth, decreasing overall with increasing depth. Forty‐five percent of surviving plugs and 50% of sprigs exhibited horizontal rhizome extension. Mean rhizome extension after 2 years was 9.5 cm/plug (1–23 cm) and 18.3 cm/sprig (0.5–31 cm). Declines in PU survival and variable growth correlate with site‐specific variability in light climate. Plug transplantation was deemed the most suitable method for further manual seagrass rehabilitation, exhibiting higher survival across all sites and conditions; however, they are costly to deploy. Sprig PUs have greatest potential in shallow water with fine sands, moderate water movement, and maximum light availability. The low cost of deploying sprigs may outweigh their lower survival compared to plugs; further efforts should be directed to enhancing survival of sprig PUs under a wider range of conditions. Suitable locations for future rehabilitation efforts in Cockburn Sound were the Eastern and Western Banks and shallow areas off Woodman Point and Mangles Bay.     

Annual, lunar and diel reproductive periodicity of a spawning aggregation of snapper Pagrus auratus (Sparidae) in a marine embayment on the lower west coast of Australia

Ichthyoplankton sampling and ovarian characteristics were used to elucidate whether the reproductive cycles of a spawning aggregation of snapper Pagrus auratus in a nearshore marine embayment were temporally and spatially specific and related with environmental conditions. The reproductive dynamics of this aggregation were studied over four consecutive years (2001-2004). Spawning occurred between September and January each year, when water temperatures ranged from 15·8 to 23·1° C. In all 4 years, the cumulative egg densities in Cockburn Sound were highest when water temperatures were between the narrow range of 19-20° C. The spawning fraction of females was monthly bimodal and peaked during new and the full moons at 96-100% and c. 75%, respectively. The backcalculated ages of P. auratus eggs collected from 16 ichthyoplankton surveys demonstrated that P. auratus in Cockburn Sound spawn at night during the 3 h following the high tide. The spatial distributions of P. auratus eggs in Cockburn Sound during the peak reproductive period in all 4 years were consistent, further implying spawning was temporally and spatially specific. High concentrations of recently spawned eggs (8-16 h old) demonstrated spawning also occurred within the adjacent marine embayments of Owen Anchorage and Warnbro Sound. Water circulation in Cockburn and Warnbro Sounds resembled an eddy that was most prominent during the period of highest egg densities, thereby facilitating the retention of eggs in these areas. The reproductive cycles of P. auratus described in this study have assisted managers with the appropriate temporal and spatial scale for a closed fishing season to protect these spawning aggregations.     

Capturing a virus while it catches its breath

The four serotypes of dengue virus present a formidable challenge for the development of efficacious human vaccines. Cockburn and colleagues, in this issue of Structure, describe the structural basis of a cross-reactive neutralizing antibody, providing greater insight into immune protection and pathogenesis.     

Thesis abstracts

Spatial and temporal heterogeneity in the epibenthic fauna of estuarine sand and seagrass beds V. A. Wadley The ecology of Pseudomys spp. in south-eastern Australia Andrew Cockburn     

Cooperate or speciate: new theory for the distribution of passerine birds

In cooperatively breeding birds, adults often forego reproduction and help care for the offspring of others. A universal explanation for this mode of breeding has eluded evolutionary biologists, who have considered it to be a rare, and largely Australian, phenomenon. In a recent paper, Andrew Cockburn reports that the number of known cooperative breeders among oscine passerine birds has more than doubled since the last substantial review, published 16 years ago. Cooperative breeding is often the ancestral trait, and predominantly cooperative genera are species poor compared with their pair-breeding counterparts. Cockburn argues that speciation is less likely in cooperative clades, because the philopatric tendencies of individuals make them poor dispersers, colonizers and migrants. This new hypothesis helps explain the distribution and composition of migrant and island avifauna. However, a major challenge remains to reconcile the roles of phylogenetic history and current ecology in promoting cooperative behaviour.     

Fish Assemblages Associated with Natural and Anthropogenically-Modified Habitats in a Marine Embayment: Comparison of Baited Videos and Opera-House Traps

Marine embayments and estuaries play an important role in the ecology and life history of many fish species. Cockburn Sound is one of a relative paucity of marine embayments on the west coast of Australia. Its sheltered waters and close proximity to a capital city have resulted in anthropogenic intrusion and extensive seascape modification. This study aimed to compare the sampling efficiencies of baited videos and fish traps in determining the relative abundance and diversity of temperate demersal fish species associated with naturally occurring (seagrass, limestone outcrops and soft sediment) and modified (rockwall and dredge channel) habitats in Cockburn Sound. Baited videos sampled a greater range of species in higher total and mean abundances than fish traps. This larger amount of data collected by baited videos allowed for greater discrimination of fish assemblages between habitats. The markedly higher diversity and abundances of fish associated with seagrass and limestone outcrops, and the fact that these habitats are very limited within Cockburn Sound, suggests they play an important role in the fish ecology of this embayment. Fish assemblages associated with modified habitats comprised a subset of species in lower abundances when compared to natural habitats with similar physical characteristics. This suggests modified habitats may not have provided the necessary resource requirements (e.g. shelter and/or diet) for some species, resulting in alterations to the natural trophic structure and interspecific interactions. Baited videos provided a more efficient and non-extractive method for comparing fish assemblages and habitat associations of smaller bodied species and juveniles in a turbid environment.     

Trace metal incorporation in otoliths of pink snapper (Pagrus auratus) as an environmental monitor

Otolith metal concentrations may be related to the environmental exposure history of fish to contamination. Otoliths of pink snapper (Pagrus auratus) collected from the marine basin of Cockburn Sound and offshore near Rottnest Island were analysed by laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) to measure the concentrations of 11 trace metals. The following metals were investigated using their respective isotopes: aluminum (²⁷Al), calcium (⁴⁴Ca), manganese (⁵⁵Mn), iron (⁵⁷Fe), copper (⁶⁵Cu), zinc (⁶⁶Zn), strontium (⁸⁸Sr), cadmium (¹¹¹Cd), barium (¹³⁸Ba), mercury (²⁰²Hg) and lead (²⁰⁸Pb). Significant differences in otolith metal concentrations were found between the sampling locations for Zn, Cd and Pb. These metals were significantly higher in the otolith edges of the pink snapper captured from the extensive industrial area bordering Cockburn Sound. Life history transects of Zn, Cd and Pb within otoliths of pink snapper sampled from Cockburn Sound typically showed temporal trends that may correspond to the movement of this fish species in and out of this contaminated area during the yearly spawning season.     

The loss of seagrass in Cockburn Sound,Western Australia. II. Possible causes of seagrass decline

This paper examines possible reasons for the extensive loss of seagrass in Cockburn Sound following industrial development. Transplanted seedlings survived poorly in Cockburn Sound compared with an adjoining embayment. Altered temperature, salinity, sedimentation and water movement do not explain the death of seagrass over wide areas, and there is no evidence for a role of pathogens. Oil refinery effluent reduced seagrass growth in aquaria at concentrations similar to those at the point of discharge, but could not account for the widespread deterioration observed in the field. Severe grazing by sea urchins was observed on meadows already under stress and does not appear to be a primary cause of decline; caged, transplanted seedlings also deteriorated.Increased light attenuation by phytoplankton blooms may have affected the ddepth to which seagrasses could survive, but would have had little significant effect in shallow water; marked phytoplankton blooms were recorded only after extensive seagrass decline had taken place. Light reduction by enhanced growth of epiphytes and loose-lying blankets of filamentous algae in nutrient enriched waters is suggested as the most likely cause of decline. Heavy epiphyte fouling was consistently observed on seagrasses in deteriorating meadows, as well as on declining, transplanted seedlings, and is known to significantly impair photosynthesis in other systems. Extensive seagrass decline coincided with the discharge of effluents rich in plant nutrients.     

The Cambridge History of the Native Peoples of the Americas: Vol. 2: Mesoamerica, Part 1.; The Cambridge History of the Native Peoples of the Americas: Vol. 2: Mesoamerica, Part 2.

The Cambridge History of the Native Peoples of the Americas: Vol. 2: Mesoamerica, Part 1. Richard E. W. Adams and Murdo J. MacLeod. eds. Cambridge: Cambridge University Press, 2000. 571 pp.
The Cambridge History of the Native Peoples of the Americas: Vol. 2: Mesoamerica, Part 2. Richard E. W. Adams and Murdo J. MacLeod. eds. Cambridge: Cambridge University Press, 2000. 455 pp.     

Evaluations of groundwater discharge rates from subsurface temperature in Cockburn Sound, Western Australia

Groundwater discharge rates were estimated from borehole groundwater temperature and pore water temperature under the seabed to be 0.92–3.6?cm/day in Cockburn Sound, Western Australia. Automated and manual seepage meters measured larger groundwater discharge rates of 13.7–16.3?cm/day. This difference may be because the observed seepage rates measured by seepage meters include not only terrestrial fresh groundwater discharge but also recirculated salt water. On the other hand, the discharge rates estimated from subsurface temperature may consist of only terrestrial fresh groundwater discharge.     

Reviews of publications

Evolutionary Dynamics of a Natural Population. The Large Cactus Finch of the Galapagos , by B. Rosemary Grant & Peter R. Grant.
Species Dispersal in Agricultural Habitats , edited by R. G. H. Bunce and D. C. Howard.
The Dictionary of Cell Biology , edited by J. M. Lackie and J. A. T. Dow.
The Mirror of Creation , by E. J. Ambrose.
The Fate of the Forest , by Susanna Hecht and Alexander Cockburn.     

Book reviews

Book Reviewed in this article: Statistical Methods for Environmental Pollution Monitoring R. O. Gilbert Atmospheric Pollution D. Elsom. Biology and Management of Capricornis and Related Mountain Antelopes Edited by H. Soma. Social Behaviour in Fluctuating Populations Andrew Cockburn. The Evolution of Insect Life Cycles Edited by Fritz Taylor and Richard Karban. The Pheasant: Ecology, Management and Conservation David Hill and Peter Robertson. Kangaroo Harvesting and the Conservation of Arid and Semi-arid Lands Edited by Daniel Lunney and Gordon Grigg.     

Pragmatic Women and Body Politics and Maternities and Modernities: Colonial and Postcolonial Experiences in Asia and the Pacific

Pragmatic Women and Body Politics. Margaret Lock and Patricia A. Kaufert. eds. Cambridge, UK: Cambridge University Press, 1998. xii +364 pp.
Maternities and Modernities: Colonial and Postcolonial Experiences in Asia and the Pacific. Kalpana Ram and Margaret Jolly. eds. Cambridge, UK: Cambridge University Press, 1998. xiv. 305 pp.     

The Cambridge Encyclopedia of Human Paleopathology

The Cambridge Encyclopedia of Human Paleopathology. Arthur C. Aufderheide and Conrado Rodriguez-Martin. Cambridge: Cambridge University Press. 1998. 478 pp.     

Speaking of Feelings

Emotions in Crosslinguistic Perspective. Jean Harkins and Anna Wierzbicka. eds. Berlin: Mouton de Gruyter, 2001. 421 pp.
Metaphor and Emotion: Language, Culture, and Body in Human Feeling. Zoltan Kövecses. Cambridge: Cambridge University Press, 2000. 223 pp.
The Navigation of Feeling:. Framework for the History of Emotions. William Reddy. Cambridge: Cambridge University Press, 2001. 308 pp.     

Complex societies and anthropology: A perspective from 1979*

The Transition to Statehood in the New World, edited by G. D. Jones and R. R. Kautz. Cambridge: Cambridge University Press, 1981. ix + 254 pp.

The Inca and Aztec States 1400–1800: Anthropology and History, edited by G. A. Collier, R. I. Rosaldo and J. D. Wirth. New York: Academic Press, 1982. xx + 475 pp.

Native Lords of Quito in the Age of the Incas: The Political Economy of North Andean Chiefdoms. Frank Salomon. Cambridge: Cambridge University Press, 1986. xviii + 274 pp.

The Origins and Development of the Andean State, edited by J. Haas, S. Pozorski and T. Pozorski. Cambridge: Cambridge University Press, 1987. vi+ 188 pp.

Peruvian Prehistory; An Overview of pre‐lnca and Inca Society, edited by R. W. Keatinge. Cambridge: Cambridge University Press, 1988. xvii + 364 pp.     

Criminal Law as It Pertains to Patients Suffering from Psychiatric Diseases

The McNaughton rules for determining whether a person can be successfully defended on the grounds of mental incompetence were determined by a committee of the House of Lords in 1843. They arose as a consequence of the trial of Daniel McNaughton for the killing of Prime Minister Sir Robert Peel’s secretary. In retrospect it is clear that McNaughton suffered from schizophrenia. The successful defence of McNaughton on the grounds of mental incompetence by his advocate Sir Alexander Cockburn involved a profound shift in the criteria for such a defence, and was largely based on the then recently published “scientific” thesis of the great US psychiatrist Isaac Ray, entitled A Treatise on the Medical Jurisprudence of Insanity. Subsequent discussion of this defence in the House of Lords led to the McNaughton rules, still the basis of the defence of mental incompetence in the courts of much of the English-speaking world. This essay considers one of these rules in the light of the discoveries of cognitive neuroscience made during the 160 years since Ray’s treatise. A major consideration is the relationship between “the power of self-control” and “irresistible impulse” as conceived by Cockburn on the one hand, and by cognitive neuroscience on the other. The essay concludes with an analysis of the notion of “free will” and of the extent to which a subject can exert restraint in the absence of particular synaptic connections in the brain.     

The Cambridge encyclopedia of human growth and development

The Cambridge Encyclopedia of Human Growth and Development. Edited by Stanley J. Ulijaszek, Francis E. Johnson, and Michael A. Preece. Cambridge, UK: Cambridge University Press. 1998. 497 pp. ISBN 0-521-56046-2. $95.00 (cloth).     

Doctors for Democracy: Health Professionals in the Nepal Revolution; East African Doctors: A History of the Modern Profession; Immigrant Physicians: Former Soviet Doctors in Israel, Canada, and the United States

Doctors for Democracy: Health Professionals in the Nepal Revolution. Vincanne Adams. Cambridge and New York: Cambridge University Press, 1998. xii. 251 pp.
East African Doctors:. History of the Modern Profession. John lliffe. Cambridge and New York: Cambridge University Press, 1998. xii+ 336 pp.
Immigrant Physicians: Former Soviet Doctors in Israel, Canada, and the United States. Judith T. Shuval and Judith H. Bernstein. eds. Westport, CT: Praeger, 1997. + 220 pp.