Inter-annual variation in the cephalopod component of the diet of the wandering albatross, <Emphasis Type="Italic">Diomedea exulans</Emphasis>, breeding at Bird Island,South Georgia

Cephalopods play an important role in the diet of many predators of the Southern Ocean. We investigated the cephalopod component of the diet of the wandering albatross, during breeding at South Georgia, from 269 boluses containing more than 34,000 beaks (corresponding to 19,452 individual cephalopods), collected between 1989 and 1999, and assessed the inter-annual variability of the cephalopod species, the level of scavenging on cephalopods by wandering albatrosses and the relationships between cephalopod availability and wandering albatross breeding parameters (breeding period, breeding success, fledging period, fledging success, egg mass and chick mass). We also proposed possible foraging areas of wandering albatrosses based on the cephalopods eaten. The cephalopod component of the diet of wandering albatrosses was relatively stable over the 11 years of the study. By number of lower beaks, three species predominated in the cephalopod component of the diet: Kondakovia longimana (29.5% of the total number of lower beaks; family Onychoteuthidae), Taonius sp. (20.4%; family Cranchiidae) and Histioteuthis sp. B (19.5%; family Histioteuthidae). K. longimana was consistently the predominant cephalopod species by mass in every year of the study (range 60.2-88.7% of mass contribution to diet). A minimum estimate of 30% of the number of cephalopods scavenged corresponded to 85% of the total mass of the cephalopods that contributed to the diet. Wandering albatrosses fed consistently more on "Antarctic" cephalopods than on "sub-Antarctic" or "subtropical" cephalopods in all years of the study, suggesting that Antarctic waters are an important foraging area for wandering albatrosses. Although some significant correlations between cephalopod abundance and wandering albatross breeding parameters existed (e.g. correlation between Taonius sp. by number and fledging success), none included K. longimana. When comparing groups of variables (using canonical analysis), no correlations were found between the most important cephalopod species (by number and by mass), total mass of squid consumed, cephalopod diversity index (H) for each year, and wandering albatross breeding parameters. This may reflect the possibility that other components in the diet (e.g. fish and carrion) are more important or, more likely, that the consistency across years of the wandering albatross breeding performance indicates that it is well buffered against fluctuations in prey availability.     

Cephalopod prey of the grey-headed albatrossDiomedea chrysostoma

Cephalopod remains were collected, at regular intervals throughout the fledging period, from the stomach contents of chicks of the grey-headed albatrossDiomedea chrysostoma at Bird Island, South Georgia, in 1984 and 1986 and from regurgitations of adults at the nest in 1986. The 1984 sample was taken during a season characterised by abnormal local oceanographic conditions in which the breeding success was very low; in 1986 conditions were normal and breeding success was high. Cephalopod beaks (289 from adults; 5 651 from chicks) were identified, and allometric equations were used to estimate the biomass represented. Five cephalopod species belonging to five families (Gonatidae, Onychoteuthidae, Psychroteuthidae, Ommastrephidae and Cranchiidae) contributed 98% by number and 97% of the biomass fed to chicks. The most important species was the ommastrephidMartialia hyadesi, contributing 68.9 to 77.4% by number and 72.5 to 79.3% of the total biomass fed to chicks. The relative proportions of cephalopod species in the chicks' diet were similar between 1984 and 1986, but the total number and biomass was significantly less in 1984. There is evidence of growth ofM. hyadesi between January and June.     

Cephalopod remains from sperm whales caught off western Canada

Of 379 cephalopod beaks sampled from stomachs of 20 sperm whales caught to the west of Vancouver Island, Canada, 152 beaks were sorted and measured. Thirteen types of beak were identified as belonging to eleven families. The most numerous species represented are Berryteuthis magister and Moroteuthis robusta comprising 28.9 and 24.3% respectively. These species were estimated to comprise 17.6 and 61.9% respectively of the weight of flesh represented by beaks.     

Effects of the 1983-El Niño on growth and carbon and nitrogen metabolism ofPleurophycus gardneri (Phaeopyceae: Laminariales) in the northeastern Pacific

Growth and compounds of carbon and nitrogen of the northeast Pacific kelpPleurophycus gardneri (Laminariales, Laminariaceae) were assessed before, during and after the 1983-El Niño Souther Oscillation event. This 2-yr study provides evidence that reduced ambient levels of nitrate and phosphate from March until August/September, 1983, in combination with elevated seawater temperature, caused a significant impairment of growth. Blade surface area, blade length, total fresh weight, and dry weight on an areal basis were significantly reduced in 1983 compared to 1982 (P<0.01). They were also significantly smaller in 1984 than in 1983 (P<0.05). The C:N values obtained both in May and July 1983 were considerably higher than in 1982, while those in May 1984 were strikingly smaller than in both 1982 and 1983. Mannitol content of the mibrid in May 1983, exhibited the highest levels recorded during the 2-yr study period, with ca. 19% dry weight and significantly exceeded mannitol content measured in May 1982 (average: 13%) and in May 1984 (average: 8%). The concentration factor for internal vs external nitrate in the midrib was 700 x ambient in May 1982 and 1984 compared with 20 x in May 1983. Ninhydrin positive substances (NPS) averaged 117 mol g dry wt^-1 in May 1984 compared with ca. 50 mol in May 1982 and 1983. The pigment ratios chlorophyllc: chlorophylla and fucoxanthin: chlorophylla in May 1983 were similar to those obtained in 1982, but were significantly different in May 1984. It is suggested that the interactive effects of temperature stress and nutrient limitation in 1983 caused a disruptive influence on C- and N-metabolism ofPleurophycus gardneri, which still affected growth performance in 1984.     

Cephalopod remains from the stomach of a sperm whale stranded off Patagonia

The stomach of a male sperm whale (Physeter macrocephalus) stranded near Comodoro Rivadavia, Argentina, on 21 March 1986, contained 247 cephalopod beaks (128 upper and 119 lower). The lower beaks were identified, their rostral lengths were measured and used to estimate the mantle lengths and wet weight of the representatives of each cephalopod taxon. Fifteen species from nine families were represented. The most numerous species, in order of decreasing abundance, were the large cranchiidMesonychoteuthis hamiltoni (32.8% of total numbers),Mastigoteuthis sp. A (16.0%), andKondakovia longimana andHistioteuthis atlantica (both 13.5%). Almost 85% of the estimated total weight was contributed by two species,Mesonychoteuthis hamiltoni (61.6%) andK. longimana (23.1%). The presence of beaks fromK. longimana, Alluroteuthis antarcticus andM. hamiltoni, which are all thought to be restricted to the Antarctic, suggests that the whale had migrated North prior to stranding.     

Cephalopod remains from the stomach of a sperm whale stranded at Rio Grande do Sul in Brazil

The stomach of a 10.2 m (34 ft) male sperm whale which became stranded at Rio Grande do Sul near Rio Grande, Brazil contained 227 upper cephalopod beaks and 255 lower cephalopod beaks. The lower beaks were identified and measured. Beaks of 14 species belonging to 9 families are present. Lower, rostral lengths are compared with those of the same species collected from stomachs of whales killed off South Africa and in the Antarctic. Estimates of the weight of flesh of the various species represented by beaks are made. Two ommastrephid species are estimated to contribute 33.1% of the weight of flesh represented by beaks while the octopoteuthids contribute 28.3% and the Onychoteuthids 18.5%. Three Antarctic species in the stomach show that the whale had migrated from south of Lat. 40°S prior to being caught and had not eaten much food during the journey which would probably have taken him more than 5 d.     

Residues of Organochlorinated Pesticides in Eggs of Water Birds from Tai Lake in China

The levels of organochlorine compounds in eggs of water birds from the colony on Tai Lake in China were studied. The eggs were collected in 2000 and belonged to the following species: 65 samples of black-crowned night heron (Nycticorax nycticorax), 36 samples of little egret (Egretta garzetta), 26 samples of cattle egret (Bubulcus ibis) from 13 clutches and 43 samples of Chinese pond heron (Ardeola bacchus) from 17 clutches. Dichlorodiphenyltrichloroethane (DDT) and its derivates (DDE and DDD), hexachlorocyclohexane (HCH) and its isomers (-HCH, -HCH, -HCH, -HCH), heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, endrin aldehyde, -endosulfan, -endosulfan, and endosulfan sulfate were determined in the laboratory by gas chromatography. The data showed that DDE had the highest levels in all the samples, followed by -HCH. The mean levels of DDE among the water bird species were in the order as follows: black-crowned night heron (5464.26ng/g, dry weight) > Chinese pond heron (2791.12ng/g, dry weight) > little egret (1979.97ng/g, dry weight) > cattle egret (660.11ng/g, dry weight). DDT and its metabolites accounted for 90% of the total organochlorines, except that it was only 73% for cattle egret. The differences of the residue among the bird species were statistically significant and could be attributed to their variations in prey and habitat. Although the DDE burdens in Tai Lake were much lower than 8 g/g (wet weight) which are thought to have significant adverse effects on black-crowned night herons, they would be expected to increase the risk of adverse effects on survival of chicks of herons and egrets, particularly black-crowned night heron, based on the critical value of 1 g/g (wet weight) DDE. The burdens of HCHs in this study were higher and the cyclodienes were lower than those found elsewhere.     

Correlates of male mating success in the ruff Philomachus pugnax,a lekking shorebird

Summary Male ruffs (Philomachus pugnax), a lekking shorebird, can generally be divided into two morphs according to behavior and plumage coloration. Predominantly dark-colored, independent male ruffs defend small territories on a lek, whereas lighter colored satellite males are non-territorial and less site-faithful to a particular lek. The traits associated with the mating success of independent male ruffs were studied at two leks during two seasons on the island of Öland, Sweden in May and June of 1985 and 1987. Using multivariate analyses, three characteristics were found to be significantly related to mating success: high frequency of visits by satellites to an independent male's residence, consistency of lek attendance, and low rates of aggressive behavior. In contrast, mating success was unrelated to the degree of darkness of the independent male nuptial plumage, territory location on the lek, or rate of courtship displays. The use of multivariate analyses helped to resolve conflicting conclusions from previous studies which employed simple statistical analyses, or none at all. Experimental manipulations are suggested which will help to further determine the influence of female mate choice in this lekking system.     

Effect of near-bottom currents on detection of bait by the abyssal grenadier fishes Coryphaenoides spp., recorded in situ with a video camera on a free vehicle

Free vehicles carrying bait, video cameras and current meters were deployed at three sites in the abyssal North Pacific Ocean in 1983 and 1984 (at depths of 3 800, 4 400 and 5 800 m). From the recovered video recordings, we analyzed responses of the abyssal grenadier fishes Coryphaenoides spp. to the bait, and, from the recovered current meters, we determined the velocities of the nearbottom tidal currents. The grenadiers consistently arrived at the camera within minutes after it landed (7.5 to 41 min, N=9 deployments), but the times of the first arrivals tended to increase within increasing distance from shore (which was correlated with increasing depth). Faster responses occurred near times of peak, as opposed to slack, current velocities. Behavioral observations suggest that grenadiers primarily use olfaction in locating the bait, because 75% of early arrivals came from down-current. Those coming from up-current typically did not appear to sense the bait until arriving down-current from it. A wait rather than search strategy is proposed for the use of food falls by these deep-sea scavengers.     

Grazing by adult estuarine calanoid copepods of the Chesapeake Bay

Grazing by adult female Eurytemora affinis, Acartia tonsa and A. clausi on natural distributions of particles from the Chesapeake Bay has been investigated. During the course of a year's sampling, a wide variety of particle size-biomass distributions were observed as seasonal shifts in detritus, and over 150 algal species occurred. These distributions were grouped into 5 basic types in the analyses of feeding. All three species demonstrated similar capabilities for feeding over a broad range of particle size with selection (higher filtering rates) on larger particles and on biomass peaks. Feeding on multiple-peak distributions resulted in strong selection or tracking of each biomass peak with reduced filtering rates between peaks. Evidence is presented which suggests that the copepods first feed on large particles and then successively switch to biomass peaks of the smaller size categories. Comparisons of the feeding behavior of Eurytemora affinis and the Acartia species showing that the Acartia species have greater capabilities for taking large particles may be associated with modifications of their mouth parts for raptorial feeding. The results suggest considerable flexibility in copepod feeding behavior which cannot be explained solely by the mechanism of a fixed sieve.     

Larval durations and recruitment patterns of two Caribbean gobies (Gobiidae): contrasting early life histories in demersal spawners

The population dynamics of small tiger prawns (Penaeus esculentus and P. semisulcatus) were studied at three sites around north-western Groote Eylandt, Gulf of Carpentaria, Australia, between August 1983 and August 1984. Seagrasses typical of open-coastline, reef-flat and river-mouth communities were found in the shallow depths (2.5 m) at these sites. The temperature and salinity of the bottom waters did not differ among the shallowest depths of the three sites and mean values at night ranged from 21.9 to 32.0 °C, and from 30.1 to 37.5% S. Data from fortnightly sampling with beam trawls showed that virtually all post-larvae (90%) were caught in the intertidal and shallow subtidal waters (2.0 m deep). At one site, where the relationship between seagrass biomass, catches and depth could be studied in detail, high catches were confined to seagrass in shallow water, within 200 m of the high-water mark. This was despite the fact that seagrass beds of high biomass (>100 g m^-2 between August and February) were found nearby, in only slightly deeper water (2.5 m). It is likely, therefore, that only the seagrass beds in shallow waters of the Gulf of Carpentaria act as important settlement and nursery areas for tiger prawns. In general, catches of tiger prawn postlarvae (both P. esculentus and P. semisulcatus) and juvenile P. esculentus on the seagrass in the shallowest waters at each site were higher in the tropical prewet (October–December) and wet (January–March) seasons than at other times of the year. Juvenile P. semisulcatus catches were highest in the pre-wet season. While seasonal differences accounted for the highest proportion of variation in catches of tiger prawn postlarvae and juvenile P. semisulcatus, site was the most important factor for juvenile P. esculentus. In each season, catches of juvenile P. esculentus were highest in the shallow, open-coastline seagrass, where the biomass of seagrass was highest. The fact that the type of seagrass community appears to be more important to juvenile P. esculentus than to postlarvae, suggests that characteristics of the seagrass community may affect the survival or emigration of postlarval tiger prawns. Few prawns (<10%) from the seagrass communities in shallow waters exceeded 10.5 mm in carapace length. Despite the intensive sampling, growth was difficult to estimate because postlarvae recruited to the seagrass beds over a long period, and the residence times of juveniles in the sampling area were relatively short (8 wk).     

Littoral infauna of a West African estuary: An oil pollution baseline survey

Littoral infaunal density was recorded from December 1983 to October 1984 throughout the Bonny Estuary in the Niger delta, Nigeria, to provide a baseline for the monitoring of oil pollution. Results on the most abundant faunal elements, polychaetes and the fiddler crabUca tangeri L., are presented. In the upper reaches, polychaete density peaked in January — due to increases in the abundance of the principal species. In the lower reaches, euryhaline and stenohaline polychaetes exhibited maxima in April to July and lesser peaks earlier and later in the year. There were no wide fluctuations in the middle reaches, due to the lack of truly estuarine species — exceptU. tangeri which was most abundant between December and April. Features such as the salinity/substrate zones, faunistic components and reduction of species upstream, are typical of estuaries elsewhere. Others, including the low abundance of all species in the middle reaches, and the occurrence of species minimum far downstream of 5 S, are atypical, and pollution from the Okrika oil terminal, oil from outboard engines, and substrate disturbance by shipping, are suggested as causative factors.     

Distribution et synécologie des fonds à Gryphus vitreus (Brachiopoda) en Corse

In the Mediterranean Sea, the brachiopod Gryphus vitreus (Born) was collected off Corsica by dredging and trawling during three cruises (June 1983; April and July 1984) and from along the French continental coast by dredging during many cruises (1975–1985). The upper limit of its bathymetric distribution lies between 115 and 125 m (rarely, from 90 m), the lower limit between 140 and 200 m depth, forming a belt along the edge of the continental shelf. The horizontal distribution of G. vitreus varies from 250 m to >4 km, and is directly related to geomorphological and hydrodynamic variations resulting from local topography and/or geographical location. The G. vitreus bottoms are bounded on the continental slope by the bathyal mud biocoenosis and on the shelf by the coastal detritic or shelf-edge detritic biocoenosis, both circalittoral. The bottoms correspond to a bathylittoral ecosystem characterized by (1) prevailing environmental conditions which result in a biotope characterized by coarse detritic sediment clogged by fine sand and mud with a high content of small hard substrates, by constant moderate bottom-currents which become weaker with increasing depth, and by small annual variations in temperature and salinity; the occurrence of an ostreobium sp. alga in the shell of G. vitreus indicates the involvement of the phytal system, as defined by Pérès (1982); (2) the G. vitreus biocoenosis, comprised of characteristic macrobenthic stocks (particularly polychaetes, mollusks, and epifaunal species on small hard substrates). Whatever the geomorphology, neighbouring circalittoral and bathyal biocoenoses have little influence on the G. vitreus biocoenosis, which displays a comparatively greater species richness and density. However, immigration of circalittoral species is encouraged by detrital sediments and water currents. The occurrence of this ecosystem as a distinct belt intercalated between circalittoral and bathyal zones is discussed. The ecosystem is considered to be bathylittoral.     

The common jellyfish Aurelia aurita: standing stock,excretion and nutrient regeneration in the Kiel Bight,Western Baltic

The population dynamics, ammonia and inorganic phosphate excretion, and nutrient regeneration of the common jellyfish Aurelia aurita was investigated from 1982 to 1984 in the Kiel Bight, western Baltic Sea. During summer 1982, medusae abundance ranged between 14 and 23 individuals 100 m^-3, biomass was estimated at about 5 g C 100 m^-3 and the mean final diameter of individuals was 22 cm. Abundance, based on numbers, in 1983 and 1984 was an order of magnitude lower; biomass was less than 2 g C 100 m^-3 and jellyfish grew to 30 cm. During the summers of 1983 and 1984, A. aurita biomass constituted roughly 40% of that of the total zooplankton>200 m. In 1982, for which zooplankton data were lacking, it was assumed that medusae biomass was greater than that of all other zooplankton groups. Total ammonia excretion ranged between 6.5 and 36 mol h^-1 individual^-1, whereas inorganic phosphate release was 1.4 to 5.7 mol h^-1 individual^-1. Allometric equations were calculated and exponents of 0.93 for NH₄–N release and 0.87 for PO₄–P excretion were determined. Nitrogen and phosphorus turnover rates were 5.4 and 14.6% d^-1, respectively. In 1982, the medusae population released 1 100 mol NH₄–N m^-2 d^-1, about 11% of the nitrogen requirements of the phytoplankton. The inorganic phosphate excretion (150 mol m^-2 d^-1) sustained 23% of the nutrient demands of the primary producers. In the other two years the nutrient cycling of the medusae was much less important, and satisfied only 3 to 6% of the nutrient demands. It is suggested that in some years A. aurita is the second most important source of regenerated nutrients in Kiel Bight, next to sediment.     

Severe storm disturbances and reversal of community structure in a southern California kelp forest

Regular observations made over a period of 5 yr in four permanent transects provided data on plant, sea urchin, and fish densities which indicate that two unusually severe winter storms in 1980 (Storm I) and 1983 (Storm II) had different effects on a southern California kelp-forest community. Storm I removed all canopies of the giant kelp Macrocystis pyrifera, but spared most understory kelps, mainly Pterygophora californica. Hence, the previously large accumulation of detached drift kelp, mostly M. pyrifera, disappeared. Denied their preferred diet of drift kelp, the sea urchins Strongylocentrotus franciscanus and S. purpuratus then emerged from shelters to find alternative food. Without effective predators, they consumed most living plants, including the surviving understory kelps. This weakened the important detritus-based food chain, as indicated indirectly by declining abundances of algal turf and fish (Embiotocidae) that eat small animals living in turf. In 1983, Storm II reversed the process by eliminating exposed urchins, while clearing rock surfaces for widespread kelp settlement and growth. By summer 1984, the kelp grew to maturity to form extensive canopies despite elevated water temperatures during summer and fall of 1983. Thus, severe storms may have vastly different effects on community structure, depending on the state of the community before the disturbance.     

Siblicide,parent-offspring conflict,and unequal parental investment by egrets and herons

Summary O'Connor (1978) generated behavioral predictions from Trivers's (1974) theory of parent-offspring conflict (POC) in relation to avian brood reduction, especially for species using escalated sibling aggression. In general, when daily mortality rates fall between certain values (the mortality difference thresholds for parents and surviving offspring: O'Connor 1978), POC is expected. At such times parents and the early-hatching senior offspring are expected to disagree on the necessity, or at least timing, of the victim chick's death. Because that death is promoted directly by the senior chicks and because parents have realistic means of nullifying those efforts, behavioral conflict is expected. I examined the activities of all family members in one siblicidal (great egrets, Casmerodius albus) and one nonsiblicidal brood-reducing species (great blue herons, Ardea herodias) of ardeidae in Texas nesting colonies. Daily mortality rates over two breeding seasons approximated the predicted POC zone for four-chick (B/4) heron broods and three-chick (B/3) egret broods. As predicted, egret sibling aggression was significantly lower in two-chick broods. Herons seldom fought, regardless of brood size. Special attention was paid to the egret B/3 data for behavioral manifestations of POC. Parents did not interfere overtly with sibling fights (99.2% of 2,829), but parents seemed to have a subtle mollifying effect on the aggression (fewer sever fights occurred when parents were present). Parents showed no favoritism in food distribution to dying victim chicks. The mixed results are consistent with two rather different POC interpretations: (1) that significant conflict exists and the offspring are winning or (2) that there is no significant evolutionary conflict. In the latter case, parents are regarded as creating asymmetries among offspring (e.g., via hatch asynchrony), then leaving competition among siblings to run its course without further intervention (laissezfaire policy). This view explicitly recognizes that siblicide and other investment-skewing selfish chick behaviors may serve parental interests well-i.e., that equal allocation of resources is not likely to be the parental optimum. Using the relative reproductive values of each nestling as an index of the parent's unequal parental investment optimum produces a closer fit to the observed food distribution skew, but does not resolve the question of whether conflict remains.     

Fish and squid in the diet of king penguin chicks,Aptenodytes patagonicus,during winter at sub-antarctic Crozet Islands

The diet of king penguins, Aptenodytes patagonicus, rearing chicks was studied during three consecutive austral winters (1990, 1991 and 1992) at Crozet Islands. The mean stomach content mass of the 47 samples was 503 g. Percentages of wet and reconstituted masses showed that both fishes (66 and 36%, respectively) and squid (34 and 64%) are important components of the winter diet. Juveniles of the demersal onychoteuthid squid Moroteuthis ingens form the bulk of the cephalopod diet, and this was the main prey by reconstituted mass (57%). Myctophid fish (lantern-fishes) accounted for most of the fish diet, constituting together 32% by mass. The three main species of myctophids eaten in summer by king penguins were either very rare in winter (Electrona carlsbergi) or accounted for a smaller proportion of the diet (Krefftichthys anderssoni = 1.5% by mass and Protomyctophum tenisoni = 4.6%). Five other myctophids, which are rarely consumed in summer, contributed 24% of the diet by mass in winter (Gymnoscopelus piabilis = 18.1%, Lampichthys procerus = 2.4%, G. nicholsi = 1.3%, and Metelectrona ventralis and Electrona subaspera = 1.0%). The greater diversity of prey in winter suggests a more opportunistic feeding behaviour at a time probably marked by a change in prey availability. Both the known ecology of the fish and squid prey and the barely digested state of some items suggest that in winter breeding adults forage in the outer shelf, upper slope and oceanic areas in the close vicinity of the Crozet Islands to feed their chicks. Finally, using king penguins as biological samplers, the present work provides novel data on the previously unstudied mesopelagic/epibenthic marine community in waters surrounding the Crozet Islands. Seventeen myctophid fish have been identified to species level. These include several poorly known species in the southern Indian Ocean. The occurrence of small, nearly intact, cephalopods in the diet of king penguins suggests that spawning grounds of four squid species may be located near the Crozet Archipelago.     

Concentration and distribution of heavy metals in tissues of two cephalopods,Eledone cirrhosa and Sepia officinalis,from the French coast of the English Channel

The concentrations of 11 heavy metals (Ag, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn) were measured in the tissues (digestive gland, branchial hearts, gills, digestive tract, kidney, genital tract, muscle, skin, shell) of the two cephalopods Eledone cirrhosa (d'Orb.) and Sepia officinalis (L.) collected from the French coast of the English Channel in October 1987. The tissues of both species displayed a similar pattern of heavy-metal accumulation: the digestive gland, branchial hearts and kidney were the major sites of concentration for all 11 metals; the digestive gland accumulated silver, cadmium, cobalt, copper, iron, lead and zinc, the branchial hearts high concentrations of copper, nickel and vanadium, and the kidney high concentrations of manganese, nickel and lead. The digestive gland, which constituted 6 to 10% of the whole-animal tissue, contained >80% of the total body burden of Ag, Cd and Co and from 40 to 80% of the total body burden of the other metals. The ratios between heavy metal concentrations in the digestive gland and those in the muscle separated the elements into three groups, those with a ratio 10 (Cr, Mn, Ni, Pb, V, Zn), those with a ratio >10 to <50 (Co, Cu, Fe), and those with a ratio 50 (Ag, Cd). The digestive gland of cephalopods (carnivorous molluscs whose age can be easily calculated with great accuracy) would seem to constitute a good potential indicator of heavy metal concentrations in the marine environment.     

Spatial and temporal variation in the diet of a high trophic level predator,the Australian fur seal (<Emphasis Type="Italic">Arctocephalus pusillus doriferus</Emphasis>)

This study quantifies the manner in which Australian fur seals, Arctocephalus pusillus doriferus, use their prey in a spatial and temporal context. We analysed 977 scat and 66 regurgitate samples collected from Tasmanian breeding colonies and haul-outs between 1994 and 2000. Diagnostic prey remains identified in the scats represented 35 fish taxa and 8 cephalopod taxa. The main taxa identified in scats, where frequency of occurrence was 10%, were leatherjacket species (family Monocanthidae), redbait (Emmelichthys nitidus), barracouta (Thyrsites atun), jack mackerel (Trachurus declivis) and red cod (Pseudophysis bachus). Regurgitates were dominated by cephalopods, primarily Goulds squid (Nototodarus gouldi), Octopus maorum, O. berrima/pallidus and Sepia apama. Discriminant function analyses indicated that there were generally no significant differences in the composition of the diet between colonies within a year, suggesting that prey distribution is fairly uniform throughout Bass Strait at those time scales. The diet at breeding colonies, however, exhibited significant inter- and intra-annual variation, determined by the presence of several key taxa, such as barracouta and a species of scorpionfish (family Scorpaenidae). The diet composition also varied regionally, between Bass Strait and southern Tasmania in spring 1999 and autumn 2000, with redbait, barracouta and a species of scorpionfish identified as the main taxa contributing to this difference. Redbait occurred in the diet only in southern Tasmania, whereas barracouta and scorpionfish occurred only in Bass Strait.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00227-003-1219-0.Communicated by G.F. Humphrey, Sydney     

Comparison of bacterial and algal utilization of orthophosphate in an estuarine environment

Bacterial utilization of orthophosphate in an estuarine environment has been differentiated from algal utilization by using flow-filters of 5.0, 1.2 and 0.45 m poresize. Examination by light microscopy showed that most of the bacterial population passed through a 5.0-m filter, whereas most algae were retained. In all experiments, bacterial and algal cell numbers and biomass were estimated. P-uptake by algae and bacteria was closely correlated with cell biomass. P-uptake by algae was high only in the summer months, whereas P-uptake by bacteria was high throughout the year. Neither algal nor bacterial P-uptake, however, was correlated with temperature or dissolved orthophosphate, total organic phosphate or total phosphate concentrations. Cell biomass of algae at a given time had a high correlation with dissolved organic phosphate levels in 2 weeks prior to sampling (r=0.830) and a low correlation in the 2 weeks following sampling (r=0.0005). Algal cell numbers had a high correlation with bacterial cell numbers (r=0.950). The biomass of algae and bacteria also had a high correlation (r=0.902). The rate of P-uptake from the water by algae and bacteria varied with season and with the species composition of the natural population.