Differences In Food Supply Research Articles

High regenerative capacity is a general feature within colonial dendrophylliid corals (Anthozoa, Scleractinia).

The regenerative capacity of cnidarians plays an essential role in the maintenance and restoration of coral reef ecosystems by allowing faster recovery from disturbances and more efficient small-scale dispersal. However, in the case of invasive species, this property may contribute to their dispersal and success in nonnative habitats. Given that four Indo-Pacific members of the coral genus Tubastraea have invaded the Atlantic, here we evaluated the ability of three of these species (Tubastraea coccinea, Tubastraea diaphana, and Tubastraea micranthus) to regenerate from fragments of undifferentiated coral tissue to fully functional polyps in response to differences in food supply and fragment size. For comparative purposes, another colonial dendrophylliid (Dendrophyllia sp.) was included in the analyses. All dendrophylliids displayed regenerative ability and high survival rates that were independent of whether or not food was supplied or fragment size. However, regeneration rates varied between species and were influenced by fragment size. Temporal expression of key genes of the regenerative process (Wnt and FGF) was profiled during whole-body regeneration of T. coccinea, suggesting a remarkable regenerative ability of T. coccinea that points to its potential use as a laboratory model for the investigation of regeneration in colonial calcified anthozoans.

Seasonal and large-scale spatial variability of the energy reserves and the feeding selectivity of Meganyctiphanes norvegica and Thysanoessa inermis in a Subarctic environment

Krill, as forage species, play a pivotal role in marine food webs by linking lower to upper trophic levels. Despite their ecological relevance, processes affecting their physiological condition and their feeding selectivity remain not well known. Here, we hypothesize that significant spatial fluctuations of environmental conditions in a Subarctic region affect the energy reserve content and feeding strategies of krill. To test this hypothesis, we assessed the fatty acid content and composition of two dominant northern krill species Meganyctiphanes norvegica and Thysanoessa inermis on a seasonal basis over more than 1000 km in the Estuary and Gulf of St. Lawrence (eastern Canada) and for the first time during the ice covered winter. M. norvegica exhibited large spatial variation of its energy reserve lipids, which were similar to seasonal variations found in a previous study in the same environment. In contrast, lipid content of T. inermis was much less affected by the spatial variations of environmental conditions but showed high seasonal variability. Feeding preferences assessed using fatty acid trophic markers highlight that the zooplankton standing stock could be more critical than phytoplankton to fulfill the metabolic requirements of these krill species and to build lipid energy reserves. In addition, diet comparison between both species highlights that trophic niche partitioning is present in the Gulf of St. Lawrence, however, modulated by spatial differences in food supply and oceanographic conditions.

A polyp from nothing: The extreme regeneration capacity of the Atlantic invasive sun corals Tubastraea coccinea and T. tagusensis (Anthozoa, Scleractinia)

The azooxanthellate sun corals Tubastraea coccinea and T. tagusensis have invaded and dramatically changed rocky reef habitats along the Brazilian coast. Management of invaded areas has brought discussions on its potential negative effects regarding species dispersal, including those related to fragmentation. Although fragmentation has been observed in unmanaged localities, here we experimentally tested the sun coral ability to regenerate from undifferentiated coral tissue to fully functional polyps in response to differences in food supply, temperature, and fragment size. In general, survival and successful regeneration were high and markedly similar for both species. However, while percent of tissue retraction/reorganization (a proxy of metabolic cost) responded to fragment size and temperature, mouth development was faster in fed fragments. Together, our findings indicate that sun coral fragments may regenerate at temperatures that lead to extensive bleaching in native scleractinians that harbor Symbiodinium. Although no doubts remain about the necessity and efficacy of the management of invasive Tubastraea spp., recovery of undifferentiated coral tissue to fully functional polyps may contribute to their invasion success and should be taken into account during management efforts.

Unexpectedly High Detections of Wolverine (Gulo gulo) in Southwestern British Columbia

We conducted an inventory of Wolverines (Gulo gulo) in southwestern British Columbia in winter 2012, using a multi-method approach of non-invasive genetic tagging and camera trapping. We detected a minimum of 4 females and 2 males at 5 hair-snag stations within an area of approximately 225 km2, which exceeded expectations based on predictions of low habitat quality and density from a broad-scale provincial model. Results were consistent with known adult intrasexual spacing patterns, suggesting that individuals were unlikely to represent members of a family group; however, overlap of territories could be a possible explanation of our results given the presence of potentially high-quality habitat features in our study area. Another possibility is that Wolverine density is higher in this part of the province than predicted by the model, potentially due to differences in food supply and key landscape features between this area and the areas where the model was developed. Further research is recommended to allow us to distinguish among competing hypotheses and fill data gaps on Wolverine ecology in this poorly studied coastal-transitional mountainous ecosystem.

Partitioning the contributions of mega-, macro- and meiofauna to benthic metabolism on the upper continental slope of New Zealand: Potential links with environmental factors and trawling intensity

Understanding and predicting change in deep-sea benthic ecosystem function remains a major challenge. Here, we conducted analyses combining data on the abundance and biomass of benthic fauna and sediment community oxygen consumption (SCOC) on New Zealand’s continental margin to estimate and compare the contributions of meio-, macro-, and megafauna to total benthic metabolism and identify potential links with environmental factors and trawling intensity. We focussed on two regions in close proximity-the high surface primary productivity Chatham Rise and low surface productivity Challenger Plateau. Mean megafauna biomass was twenty times greater on Chatham Rise than Challenger Plateau, likely reflecting differences in food supply between the two regions; this contrast in megafaunal biomass was mainly due to differences in mean body weight rather than abundance. Meio- and macrofauna made similar contributions to SCOC and together accounted for 12% of benthic metabolism on average. In contrast, the estimated contribution of megafauna never exceeded 1.5%. Significant positive correlations between faunal respiration and food availability indicate a link between food supply and benthic community function. Our analyses also show that fauna made a greater contribution to SCOC in conditions of high food availability, and that microorganisms (i.e., the proportion of SCOC not accounted for by the fauna) tended to be more dominant at sites with low food availability. These findings provide support for the concept that large organisms are more strongly affected by a reduction in food resources than small organisms, which in turn underlies one of the most widely described patterns in the deep-sea benthos, i.e., the reduction in organism body size with depth. Because metabolism in deep-sea sediments is typically dominated by microorganisms and small fauna, the absence of a relationship between bottom trawling intensity and the respiration of benthic fauna in the present study may be explained by benthic communities shifting towards smaller body size following physical disturbance. Future studies of deep-sea benthic ecosystem function will need to quantify the indirect influence of fauna on microbial metabolism through activities such as feeding and bioturbation in order to better understand the total contribution of benthic fauna to benthic processes.

Contrasting patterns of α- and β-diversity in deep-sea bivalves of the eastern and western North Atlantic

We analyzed patterns of α- and β-diversity in deep-sea bivalves collected by epibenthic sleds from the western North Atlantic south of New England, and from the eastern North Atlantic in the Rockall Trough, Porcupine Seabight and Porcupine Abyssal Plain. In the western North Atlantic, species diversity, measured as the normalized expected number of species, shows a unimodal bathymetric trend peaking at mid-bathyal depths. In the eastern North Atlantic, diversity increases monotonically with depth reaching a maximum at abyssal depths. We used Baselga's (2010) metrics to distinguish two separate components of β-diversity along depth gradients, species dissimilarity among sites due to spatial replacement (turnover) and species loss leading to nestedness. We also examined the rank order of nestedness with depth using Rodríguez-Gironés and Santamaría's (2006) BINMATNEST. The primary difference in β-diversity between west and east centers on the composition of abyssal communities. In the western North Atlantic, abyssal assemblages are nested subsets of bathyal assemblages. In the eastern North Atlantic, turnover dominates at all depths. These very fundamental differences in community structure between the basins may be attributable to differences in food supply, which is greater in the eastern North Atlantic region sampled. POC-flux to abyssal depths in the east may not reach levels low enough to depress species diversity as it does in the west. In the west, the abyssal fauna is largely an impoverished nested subset of the bathyal fauna that shows less endemism and may be maintained partly by source–sink dynamics.

Relationships between body burdens of trace metals (As, Cu, Fe, Hg, Mn, Se, and Zn) and the relative body size of small tooth flounder (Pseudorhombus jenynsii)

Several studies have described strong relationships between body size and the accumulation of trace metals in animal tissues. However, few of these studies have utilized aging techniques to control for age related effects. We utilized relative body size (gy−1) of a model flounder species, Pseudorhombus jenynsii, in order to control for age related effects on growth and size measurements. We investigated links between relative body size, concentrations of trace metals in flounder muscle tissue, physico-chemical variables (temperature, salinity, pH, and turbidity), and levels of trace metals in the sediment. Flounder were sampled using an otter trawl net in the inner areas of eight estuaries that were either heavily modified or relatively unmodified by urbanization and industrial activity. Our results indicate that this commonly eaten fish is accumulating significant levels of some trace metals in their muscle tissue, both in relatively unmodified and heavily modified estuaries. Concentrations of Cu, Zn and Fe in muscle tissue, as well as temperature, showed a negative relationship to the relative body size of flounder. In contrast, Se and Hg in muscle showed a positive relationship to relative body size. Observed growth patterns indicate that these effects are not driven by age related differences in metabolic activity. Instead, our results suggest that differences in food supply or toxicological effects may be responsible for the observed relationships between relative body size and concentrations of Cu, Zn, and Se in muscle tissues. The use of otolith aging and growth measurement techniques represents a novel method for assessing the relationships between trace metal accumulation and the relative body size of fish in a field environment.

Impact of the Middle Miocene climate transition on elongate, cylindrical foraminifera in the subtropical Pacific

Fifty-eight species of elongate, cylindrical benthic foraminifera (here referred to as the Extinction Group) belonging to genera that became extinct during the mid-Pleistocene Climate Transition (MPT), were documented (similar to 50 kyr resolution) through the early middle Miocene (15-13 Ma) in two sites on opposite sides of the subtropical Pacific Ocean (ODP Sites 1146, South China Sea; ODP Site 1237, southeast Pacific). The study was undertaken to investigate the response of the Extinction Group (Ext. Gp) to the major cooling during the middle Miocene Climate Transition (MCT) to look for clues that might explain the causes of the extinction during the glacials of the mid-Pleistocene Climate Transition. Ext. Gp faunal differences between the two sites (attributed to regional and bathymetric differences in food supply to the seafloor) are greater than those that occurred through the 2 myr time span at either site. The middle Miocene Climate Transition was not an interval of enhanced species turnover or a decline in Ext. Gp abundance, in contrast to the major extinctions that occurred during the mid-Pleistocene Climate Transition. Distinct changes in the composition of the Ext. Gp faunas did occur through this time (more pronounced in Site 1237). At both sites the pre-middle Miocene Climate Transition faunas were transformed into their post-middle Miocene Climate Transition composition during the period of major cooling (14.0-13.7 Ma). During this transition interval the faunal composition swung back and forth between the two end member faunas. These faunal changes are attributed to changes in productivity (decrease in South China Sea, increase in southeast Pacific), brought about by major changes in global climate and continental aridity. (C) 2010 Elsevier B.V. All rights reserved.

Lipid biomarkers reveal geographical differences in food supply to the cold-water coral Lophelia pertusa (Scleractinia)

Despite its importance as an ecological engineer, little is known about the feeding eco- logy of the widespread reef framework-forming cold-water coral Lophelia pertusa. This is the first study to compare lipid signatures of L. pertusa from different areas in the North Atlantic using sam- ples from 2 sites in the eastern Atlantic and 2 seamounts in the western Atlantic. Lipid samples were collected in February, May, July and November from the Mingulay reef complex off western Scot- land, but no clear seasonal pattern was observed. High lipid content and large wax ester fractions were recorded from all sites, with the highest values recorded at the shallowest site (Mingulay). Here the prevalence of copepod lipid biomarkers — monounsaturated fatty acids 20:1(n-9) and 22:1(n-11) and their fatty alcohols — indicates L. pertusa feeds predominantly on calanoid copepods. At deeper offshore sites, the abundance of the fatty acid 18:1(n-9) and fatty alcohol 16:0 suggest a significant dietary input from non-calanoid copepods. Our results imply that the shallow Mingulay site is likely to receive a greater input of fresh surficial material and a higher abundance of herbivorous calanoid copepods, while at the deeper sites, carnivorous or omnivorous non-calanoid copepods are likely to be more abundant. L. pertusa therefore appears to be an opportunistic feeder capable of taking a variety of zooplankton prey. Further investigation is required to assess site-specific dependence on prey sources.

Reproductive differences between woodpeckers and secondary hole-nesters

Woodpeckers differ from most birds in several ways. They have powerful bills and excavate nesting cavities, and compared with most other birds of equivalent size they have relatively small clutches, relatively small eggs, and short incubation periods whereas the chicks remain in the nest for a relatively long time. Based upon the literature, I have compared the reproductive patterns of seven «true» Nordic woodpeckers (Picinae) with that of eight secondary hole-nesting species (particularly five passerines). The mean incubation period of the woodpeckers (12.4 ± 2.2 days) does not differ significantly from that of the secondary hole-nesters (17.6 ± 6.3 days; t-test, p=0.057). However, the incubation period of Picus canus and P. viridis (15.5 days) differs from the mean of the remaining woodpeckers (11.1 days; p<0.001). If the two Picus species are omitted from the analysis, the mean incubation period of the woodpeckers is shorter than that of the secondary hole-nesters (2.3 days; p=0.045). The secondary hole-nesting woodpecker species Jynx torquilla also has a shorter incubation period (12 days) than any of the other secondary hole-nesters. The mean nestling period of the woodpeckers (24.3 ± 2.9 days) does not differ from that of the secondary hole-nesters (22.7 ± 6.9 days; p=0.57). However, the woodpeckers have a longer nestling period (p=0.013) than the five passerines (mean 18.5 days). The ratio nestling period:incubation period differs, being 2.01 in woodpeckers and 1.31 in secondary hole-nesters (p<0.001). Woodpecker eggs are small and thin-shelled with a mean weight, related to the body mass of females, of 6.2 ± 2.0, and they are significantly lighter than those of the eight secondary hole-nesters (9.5 ± 2.0; p=0.007). The mean eggshell thickness in relation to egg volume is less in woodpeckers (1.3 ± 0.5) than in the secondary hole-nesting passerines (2.4 ± 0.7; p=0.01). The mean clutch size of the woodpeckers (5.5 ± 1.5 eggs) does not differ from that of the eight secondary hole-nesters (5.9 ± 2.2 eggs; p=0.15). However, if the two Picus species are omitted because of their tendency to reuse nest holes and their clutch size (mean 7.3 ± 1.1) that is larger than that of the other woodpeckers (mean 4.9 ± 0.9; p=0.03), the woodpeckers have a smaller clutch size than the secondary hole-nesters (p=0.04). The mean clutch weight related to the female body mass is lower in woodpeckers (0.33 ± 0.11) than in the secondary hole-nesters (0.57 ± 0.24, p=0.03). Hypotheses proposed to explain why reproduction in woodpeckers differs from that of other hole-nesters are differences in nest predation, limitation in nest sites of the secondary hole-nesters, energy costs expended in excavation, differences in food supply, adult survival and life duration.

P4.013 Effects of donepezil on behavioral andpsychological symptoms in Korean patients with Alzheimer's disease

We analyzed patterns of α- and β-diversity in deep-sea bivalves collected by epibenthic sleds from the western North Atlantic south of New England, and from the eastern North Atlantic in the Rockall Trough, Porcupine Seabight and Porcupine Abyssal Plain. In the western North Atlantic, species diversity, measured as the normalized expected number of species, shows a unimodal bathymetric trend peaking at mid-bathyal depths. In the eastern North Atlantic, diversity increases monotonically with depth reaching a maximum at abyssal depths. We used Baselga's (2010) metrics to distinguish two separate components of β-diversity along depth gradients, species dissimilarity among sites due to spatial replacement (turnover) and species loss leading to nestedness. We also examined the rank order of nestedness with depth using Rodríguez-Gironés and Santamaría's (2006) BINMATNEST. The primary difference in β-diversity between west and east centers on the composition of abyssal communities. In the western North Atlantic, abyssal assemblages are nested subsets of bathyal assemblages. In the eastern North Atlantic, turnover dominates at all depths. These very fundamental differences in community structure between the basins may be attributable to differences in food supply, which is greater in the eastern North Atlantic region sampled. POC-flux to abyssal depths in the east may not reach levels low enough to depress species diversity as it does in the west. In the west, the abyssal fauna is largely an impoverished nested subset of the bathyal fauna that shows less endemism and may be maintained partly by source–sink dynamics.

Macrofauna Communities in the Eastern Mediterranean Deep Sea

Abstract. During two expeditions with RV ‘Meteor’ in summer 1993 and winter 1997/98 the structural and functional diversity of the benthic system of the highly oligotrophic eastern Mediterranean deep sea was investigated. The macrofauna communities were dominated by polychaetes even at the deepest stations.The fauna at shallow stations was dominated by surface deposit feeders, whereas subsurface deposit feeders and predators generally increased with depth. A high percentage of suspension‐feeding Porifera was found in the Levantine Basin. Mean abundance and number of taxa of both expeditions were significantly correlated to depth and distance to the nearest coast as well as to the total organic carbon (TOC) content in sediments.Numbers of taxa and abundance decreased generally with depth, although lowest numbers were not found at the deepest stations but in the extremely oligotrophic Levantine and Ierapetra Basin. Biomass measured during the second cruise was extremely low in the Ierapetra Basin and comparable to other extreme oligotrophic seas.The significant correlations found for TOC contents and macrofauna with distance to coast during both expeditions apparently reflect the role of hydrographically governed transport of organic matter produced in coastal regions into greater and extreme depths of the Mediterranean Sea.Seasonal differences in macrofauna communities due to seasonal differences in food supply were not found. However, recent large‐scale hydrographic changes (Eastern Mediterranean Transient, EMT) might change the oligotrophy and, thus, the structure of the benthic communities in the Eastern Mediterranean deep sea.

Abundance and growth of the sea urchinEchinocardium cordatum in the central North Sea in the late 80s and 90s

Abundance and growth ofEchinocardium cordatum at 28 stations on the Dogger Bank were analysed in May 1996–1998 and compared to data from 1985–1988 in order (i) to investigate the large-scale spatial variability of abundance and size ofE. cordatum in the late 80s and 90s, (ii) to relate abundance and growth ofE. cordatum to the quantity and quality of its food and (iii) to compare differences in results from the 80s and the 90s in relation to food supply and environmental changes due to hydroclimate change. In addition, phytopigment contents in the guts of sea urchins were analysed in May 1999 and compared to those in the surrounding sediments along a transect from the German Bight towards the Dogger Bank to detect differences in food supply. Differences in growth and size of the sea urchins were found to be positively correlated with total organic carbon (TOC) contents in the sediment fine fraction (<63 µm), but negatively correlated with the sediment fine fraction as well as with TOC content and C/N ratio of the total sediments. Abundances of adultE. cordatum were positively correlated with the fine fraction and sediment bulk parameters. Phytopigment analyses showed no significant differences of chlorophylla contents in the guts between the different sites, but differences in quality of the ingested material were detected. That indicates that abundance ofE. cordatum was related to food quantity, whereas growth was dependent on food quality. With regard to the long-term comparison, the decrease in abundance ofE. cordatum in the eastern shallow part of the Dogger Bank corresponded to the increased hydrodynamics which resulted in reduced food supply for surface deposit feeders such asE. cordatum.

Influence of population isolation on genetic variation and demography in Seychelles warblers: a field experiment

AbstractBetween 1959 and 1968 the entire world population of Seychelles warblers (Acrocephalus sechellensis) comprised only 26–29 individuals entirely confined to Cousin Island (26 ha). Through conservation actions the island population has reached a carrying capacity of ca 320 birds since 1982. The warbler population has significantly lower levels of genetic variation, as determined by multilocus DNA fingerprinting, compared with its mainland relative, the Australian warbler (Acrocephalus australis) and other outbred natural bird populations (mean band sharing coefficients are 0.50, 0.22 and 0.21, respectively), and has a very low annual reproductive rate of 0.28 yearlings per breeding pair. Therefore some degree of inbreeding may have occurred in this population.The relatively low level of genetic variation is not directly responsible for this low reproductive output since breeding pairs that were transferred to the islands of Aride (68 ha) and Cousine (29 ha) with similar vegetation and climate, but with higher year‐round insect food abundance, had significantly higher fecundity and survival. In contrast, no difference in reproductive success was observed between incestuous breeding pairs and non‐incestuous breeding pairs.In addition, annual production of yearlings by pairs on Aride was on average 44 times higher than that by the same pairs on Cousin before the transfer. Annual production of yearlings by pairs on Cousine, that were as inbred as those on Aride, was on average five times higher than that by the same pairs on Cousin before the transfer. Eight years after translocation, the Aride population had grown to over 1000 birds, and six years after translocation, the Cousine population had grown to 186 birds.The experiments, controlled for group size, breeding partner, breeder age and experience, showed that the differences in reproductive success by warblers on the three islands cannot be due to genetic differences because of similar band‐sharing similarities, but seem entirely accounted for by differences in food supply. Although the amount of genetic variation in the Seychelles warblers is relatively low, the demographic parameters do not indicate apparent signs of inbreeding depression in these populations.

Influence of population isolation on genetic variation and demography in Seychelles warblers: a field experiment

Between 1959 and 1968 the entire world population of Seychelles warblers (Acrocephalus sechellensis) comprised only 26–29 individuals entirely confined to Cousin Island (26 ha). Through conservation actions the island population has reached a carrying capacity of ca 320 birds since 1982. The warbler population has significantly lower levels of genetic variation, as determined by multilocus DNA fingerprinting, compared with its mainland relative, the Australian warbler (Acrocephalus australis) and other outbred natural bird populations (mean band sharing coefficients are 0.50, 0.22 and 0.21, respectively), and has a very low annual reproductive rate of 0.28 yearlings per breeding pair. Therefore some degree of inbreeding may have occurred in this population. The relatively low level of genetic variation is not directly responsible for this low reproductive output since breeding pairs that were transferred to the islands of Aride (68 ha) and Cousine (29 ha) with similar vegetation and climate, but with higher year-round insect food abundance, had significantly higher fecundity and survival. In contrast, no difference in reproductive success was observed between incestuous breeding pairs and non-incestuous breeding pairs. In addition, annual production of yearlings by pairs on Aride was on average 44 times higher than that by the same pairs on Cousin before the transfer. Annual production of yearlings by pairs on Cousine, that were as inbred as those on Aride, was on average five times higher than that by the same pairs on Cousin before the transfer. Eight years after translocation, the Aride population had grown to over 1000 birds, and six years after translocation, the Cousine population had grown to 186 birds. The experiments, controlled for group size, breeding partner, breeder age and experience, showed that the differences in reproductive success by warblers on the three islands cannot be due to genetic differences because of similar band-sharing similarities, but seem entirely accounted for by differences in food supply. Although the amount of genetic variation in the Seychelles warblers is relatively low, the demographic parameters do not indicate apparent signs of inbreeding depression in these populations.

Moulting and growth of the early stages of two species of Antarctic calanoid copepod in relation to differences in food supply

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 175:109-119 (1998) - doi:10.3354/meps175109 Moulting and growth of the early stages of two species of Antarctic calanoid copepod in relation to differences in food supply Rachael S. Shreeve*, Peter Ward British Antarctic Survey, Natural Environment Research Council, Madingley Road, Cambridge CB3 OET, United Kingdom *E-mail: rssh@pcmail.nerc-bas.ac.uk ABSTRACT: Instantaneous measurements of moulting and growth of the early copepodite stages of 2 species of Antarctic copepod, Rhincalanus gigas and Calanoides acutus, were made at 4 regions around South Georgia during austral summer 1996/1997. Sea surface temperature was ~3°C across the study area whereas chlorophyll a concentrations were considerably higher towards the western end of the island. Despite this, moulting rate experiments showed that stage durations of both species were invariably short with no significant regional differences. Stage durations of R. gigas CI, CII and CIII averaged 9, 28 and 15 d respectively, and those of CII, CIII and CIV C. acutus were 4, 7, and 16 d respectively. Daily mass-specific growth rates were lower and less variable in R. gigas (mean 0.05 d-1) than in C. acutus (mean 0.14 d-1), and showed no measurable regional differences. Those for C. acutus however, were higher off-shelf at the western end of the island where the copepodites were heavier than elsewhere. In addition to variations in concentration of chlorophyll a, qualitative differences in the microplankton food supply may also have influenced growth rates. Large diatoms were far more abundant off-shelf at the western end of the island compared to elsewhere, where micro-flagellates and small diatoms dominated. It is suggested that the more opportunistic feeding mode of R. gigas gave stability to its growth rate, whereas C. acutus, which is predominantly herbivorous, was affected by the fluctuations in phytoplankton concentrations and species composition. Moulting occurred within a narrow range of carbon and dry mass for both species, although this range varied between stations. KEY WORDS: Rhincalanus gigas · Calanoides acutus · Moulting rates · Growth · Production · Southern Ocean · South Georgia Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 175. Publication date: December 17, 1998 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1998 Inter-Research.

Habitat and area use by red fox Vulpes vulpes vixens in mid-Norway

During 1990 - 91, area and habitat use of three red fox Vulpes vulpes vixens were monitored by radiotelemetry in a mixed cultivated and coniferous forest in the county of Sør-Trøndelag, central Norway. When resting, the vixens occurred mostly in dense and mature spruce forest. In contrast, mixed forest and more open habitats also were visited during hunting. On average, the area used was 4.97 km2 (min. 2.03 km2 - max. 10.24 km2). We propose that individual difference in area use reflect differences in food supply, but breeding behaviour and the restricted mobility associated with it may also play a part.

An improved supra- and epibenthic sledge for catching Peracarida (Crustacea, Malacostraca)

Abstract A new type of epibenthic sledge is presented, which possesses an additional supranet above the epinet. Both nets are closed by an opening/closing device in the water column. The new construction allows a selective catch ofhigher suprafauna, which swims 1–1.33m above the seafloor, and a good discrimination between real suprafauna and epifauna. In total, 79581 Peracarida were sampled at 8 stations at about 75°N and 12°W, off Greenland. Of these, Isopoda were usually the most abundant group in the epinet, Amphipoda in the supranet. At the stations where suprafauna was abundant, the numbers of Mysidacea were usually higher in the epinet than in the supranet, probably due to differences in food supply, i.e. the enrichment of food in the benthic boundary layer.

The Seasonal Decline in Clutch Size: An Experiment with Supplementary Food in the Kestrel, Falco tinnunculus

To test whether the seasonal decline in cluth size in proximately determined by laying date or by parental quality an experiment with supplementary food was performed in the kestrel Falco tinnunculus. The experiment showed that supplemented pairs laid earlier and larger clutches than control pairs. Comparison of clutch size between supplemented and non-supplemented pairs laying on the same dates, showed that supplementary food affects clutch size independently of laying date. The seasonal decline in clutch size seems to occur when there are among-pair differences in food supply, since clutch size declines among non-supplemented pairs but not among supplemented pairs

North Sea Scyphomedusae; summer distribution, estimated biomass and significance particularly for 0-group Gadoid fish

Data on the by-catch of Scyphomedusae from pelagic trawls was collected during the routine ICES International 0-group Gadoid Surveys of the North Sea, in June and July of the years 1971–1986 (except 1984). These data are used to describe the distributions, abundances and biomasses of three common North Sea Scyphomedusae: Aurelia aurita (L.), Cyanea capillata (L.) and C. lamarckii (Péron & Lesuer). Information is also presented on inter-annual variability, size (umbrella diameter) frequencies and, for the Cyanea species, umbrella diameter: wet weight relationships. The general role and ecological significance of Scyphomedusae is discussed and, given the well known ‘shelter’ relationships between Scyphomedusae and certain 0-group fish, whiting ( Merlangius merlangus) and haddock ( Melanogrammus aeglefinus), in particular. The data were examined for evidence of such relationships. Aurelia aurita, although fairly widespread in the northern North Sea was virtually absent from the central North Sea but very abundant in coastal waters. This species was particularly abundant off the Scottish east coast and especially in the Moray Firth. Cyanea lamerckii was most abundant in the southern and eastern North Sea. More widespread than Aurelia, this species was also most abundant in coastal regions, particularly off the Danish west coast. Cyanea capillata, with a more northern distribution was also more widely distributed and abundant offshore. This species was most abundant in the area between the Orkney/Shetland Isles and the Norwegian Deep and in shelf waters of the north west approaches to the North Sea. As with C. lamarckii it was also, in some years, abundant off the Scottish east coast and west of Denmark. The abundance and the size frequency of the jellyfish show considerable inter-annual variability, and variability between regions of the North Sea. It is considered that hydrographic variability and differences in food supply to both medusae and to their sessile benthic polyps, are the major causes of the observed differences between years and areas. The impact of Scyphomedusae on fishing and recreational activities is discussed.