Circadian rhythmicity of locomotor behavior and oviposition in female Teleogryllus commodus

Summary Locomotor activity of the Teleogryllus commodus is under circadian control, with _LL=25.3 h and _DD=23.4 h. In LD 12:12 h, running occurs either exclusively during darkness (57%), mainly in the dark phase (35%), or with substantial activity peaks in both phases (8%). For oviposition, _LL>24 h and _DD<24 h; in LD 12:12 h, 80% of the studied deposited their eggs mainly during the light phase and 20% primarily during darkness. In the discussion, a temporal correlation between stridulation, spermatophore formation, and locomotion, and oviposition is established, which serves to make an encounter and mating between the sexes as likely as possible.Dedicated to Prof. Dr. M. Gersch on the occasion of his 70th birthday     

Are communal pukeko caught in the prisoner's dilemma?

Summary The prisoner's dilemma of game theory provides a possible explanation for communal breeding in the pukeko (Porphyrio porphyrio, Aves) where group breeding birds are at a reproductive disavantag compared to pairs. Territorial defence is largely the realm of males. A male who defect on neighbours by taking in an extra male defender and so becoming communal stands to gain territorial area and possibly higher reproductive success. Neighbours are forced to follow suit if additional males are available or lose their territory and therefore their breeding opportunities. If neighbours also admit an extra defender, the initial defector loses his advantages and all males end up with the lower breeding success of communal groups. Such defection to a communal habit appears to be the only stable solution.     

The evolution of cheating and selfish behavior

Summary We examine the necessary conditions for the spread of genes that determine selfish and cheating behaviors and the rate of spread of these genes through structured populations, in order to address the question of the invadability of altruistic systems by anti-social mutations. We find that, although cheaters always have a higher relative fitness than altruists within groups, population structures which permit the evolution of altruism also preclude invasion by anti-social mutations. These results are related to a discussion by Hamilton (1971) concerning the limits to the evolution of altruistic and selfish behaviors.     

Song as an attractant for male and female European starlings,and the influence of song complexity on their response

Summary We tested the hypothesis that song attracts females and repels males in the European starling. We broadcast recorded song from speakers attached to nestboxes, while paired boxes with silent speakers served as controls. As predicted, females were attracted to the song boxes. Contrary to prediction, males were also attracted to the `song' boxes. Singing by male starlings may be costly because it attracts competitors for limited nesting sites, but the cost cannot be avoided due to the need to attract a mate. In a second experiment simple song (composed of 20 different phrase types) and complex song (40 phrase types) were played simultaneously. More males were captured at boxes where simple song was played. Song complexity may function as an indicator of male quality and be used by male starlings to assess potential competitors.     

Lead-based paint in dwellings: The potential for contamination of the home environment during renovation

The quantity and particle size characteristics of lead in dust released during three different paint removal techniques was determined under controlled conditions and in situ in a dwelling. Air-lead and deposited dust-lead levels were highest after sanding but burning-off and hot-air removal methods also produced significant contamination. The importance of dust particle-size and lead is discussed in relation to the potential hazard to home renovators via inhalation and to children via the hand-to-mouth route.This paper is also being published in Proceedings of the Conference on Lead in the Home Environment and is one of several selected from SEGH sponsored conferences for simultaneous publication in this journal.     

Environmental influence on the locomotor activity rhythm of the sand-shore amphipod Talorchestia deshayesi

The precision and persistence of the nocturnal, surface locomotor activity rhythm of the sand-beach amphipod Talorchestia deshayesi is described. The rhythm is expressed as a circadian activity period with no evidence of a circa-tidal component associated with the time of high tide. The rhythm is light-sensitive and entrainment occurs in response to changes in the time of an experimentally simulated dusk transition. Locomotor activity is initiated at the end of the dusk transition with cessation always occurring prior to dawn. The point of activity initiation is taken to be the position of a synchronizing cue controlling entrainment. The cue appears to be an absolute irradiance level of approximately 1.0 to 2.0×10^-4 W m^-2     

Le système assimilation-régénération des sels nutritifs dans les eaux superficielles de l'océan Austral

Low primary-productivity levels in high-nutrient environments of the Southern Ocean are not yet well understood. An accurate knowledge of nutrient assimilation by phytoplankton, at the base of the pelagic food-web, therefore appears to be essential. A study of the mesoscale hydrological structure and chemical observations in the upper layers of the Indian sector of the Antarctic Ocean (Cruise MD-25 FIBEX of M.S. Marion Dufresne, January–February 1981) permitted us to develop a method for estimating nutrient consumption by phytoplankton. After strong vertical mixing in winter, the homogeneous Antarctic Surface Water (ASW) is, in summer, divided into two parts by a well-formed pycnocline. In the upper layer, corresponding approximately to the photic zone, we observed nutrient depletion resulting from photosynthetic activity, while the underlaying thermal minimum layer displayed unaltered winter characteristics, including nutrient concentrations typical of winter surface-water conditions. Taking into account the nutrient depletion in summer, we calculated the assimilation ratios for Antarctic phytoplankton as follows: ([NO ₃ ^- lower]-[NO ₃ ^- upper]):([PO ₄ upper])=N:P=11.2±2.4 and N:Si=0.27±0.05. These ratios are lower than the classical Redfield ratios (N:P=16 and N:Si=1), but are in good agreement with the elementary composition of phytoplankton samples collected during the same cruise. Moreover, they agree with previously published data on stoechiometric determinations of particulate matter in surface-water samples. Besides, in the transition layer between the lower layer and Warm Deep Water (WDW), the calculated mineralization ratios were slightly higher than the assimilation ratios: N:P=14.6 and N:Si=0.37. From these ratios, it would appear that, in these surface layers of the Southern Ocean (down to 250 m), assimilation-regeneration mechanisms operate in such a way that phosphate and silicate contents decrease much more than nitrate content during the northward drift of the surface waters. The determination of assimilation ratios taking into account the nutrient depletion of the upper layer allowed us to evaluate the carbon net-production which integrates time-space variations in the photic layer over the whole early summer period. We estimated a production rate (0.4 g C m^-2 d^-1) of the same order of magnitude as the mean value obtained by the ¹⁴C method (0.2 g C m^-2 d^-1). The theoretic silicium consumption by phytoplankton along a meridian transect, calculated using an estimated assimilation ratio of C:Si=1,85, indicates that the marked south-north decrease in silicate concentration in the Antarctic Surface Water would mainly result from biological activity. The silicate concentrations thus calculated were in good agreement with concentrations measured along a previous transect across the Southern Ocean.

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Le système assimilation-régénération des sels nutritifs dans les eaux superficielles de l'océan Austral

     

The structure of plankton communities of the Indian Ocean

Species diversity and trophic structure of plankton communities have been considered as most important biological features. The Fisher () and Simpson () indices and the information index H=- pi log₂ pi (Margalef) were used for evaluation of species diversity. The indices have been calculated within the group of filter feeders by numbers ( and H) and biomass ( and H) of the species; the best results were obtained in the latter case. The index H=- pi log₂ pi is proposed for the quantitative evaluation of trophic structure, where a portion of an individual trophic group is taken as pi. The plankton material was collected by the R.V. Vityaz in the northern Indian Ocean in January through February, 1960. Analysis of characteristics of zooplankton distribution, species and trophic diversity in connection with characteristics of the water regime resulted in the definition of 3 types of the plankton communities: (a) those in intensive divergence zones; (b) those in poor divergence zones; (c) those in regions with stable water stratification or with feebly marked convergence, distiguished by different values of biomass, species diversity, and trophic group ratios.     

Digestive carbohydrases from the hepatopancreas of two Antarctic euphausiid species (Euphausia superba and E. crystallorophias)

The hepatopancreatic extracts of Euphausia superba Dana and E. crystallorophias Holt and Tattersall collected from the Antarctic. Ocean during January 1985, are most effective in hydrolysing substrates containing (13)--glucosidic linkages. Three enzymes appear to be involved in the depolymerization of (13)--D-glucans in the euphausiid diet: (1) an exo-(13)--D-glucanase, (2) an endo-(13)--D-glucanase and (3) a -D-glucosidase. The glucanases have a pH optimum of 5.4, a temperature optimum of 50°C and are optimally extracted in bistripropane buffer, pH 7.2. Levels of (13)-D-glucanase in laboratory-cultured E. superba are inversely affected by food availability, and activities double after starvation for 12 d. The increase is due mainly to higher activities of exo-acting glucanases. -Amylase and endo-(14)--D-glucanase (cellulase) activity are also present in the extracts in addition to glycosidase activity against a range of p-nitrophenyl substrates (-and -D-glocose, - and -D-galactose, -D-xylose, - and -D-mannose). Digestive activity against several acidic polysaccharides, including the acidic mucilage polysaccharide of the ice diatom Stauroneis amphioxys, is minimal and is not induced when the polysaccharide is present in the diet of E. superba. These results indicate that some, but not all, components of the algal material in the euphausiid diet can be hydrolyzed and assimilated.     

Studies on the nutritional requirements of the larval stages of Penaeus japonicus using microencapsulated diets

Fatty acid biosynthesis in the larval stages of Penaeus japonicus Bate was examined by feeding microencapsulated diets containing (1-¹⁴C) palmitic acid, and fat-free diets supplemented with defined fatty acids. Highest larval growth rates were achieved on diets containing Tapes philippinarum lipid and, when defined fatty acids were substituted, on diets containing 20:63 fatty acid. The radioactive tracer experiments indicate that 16:17, 18:0 and 18:19 fatty acids may be synthesised from palmitic acid and that P. japonicus larvae may possess the ability to elongate 18:33 to 20:53 and 22:63, and 18:26 to 20:46. However, the rates of these reactions appear to be too slow to meet the larval requirements for essential fatty acids and the 3 series of polyunsaturated fatty acids must be provided in the diet.     

Lead Contamination of Topsoil and Vegetation in the Vicinity of a Battery Factory in Nigeria

Levels of Pb, Zn, Cu, Cr, Ni and Cd were determined in topsoil and vegetation in the vicinity of a factory manufacturing lead- batteries in Ibadan, Nigeria. The samples were collected along five transects in different directions, and varying distances up to 1000m from the factory. Soil lead levels were found to be elevated around the factory, with average levels of about 2000mgkg^–1 close to the fence that declined gradually to about 50mgkg^–1 some 750m away. Soil-lead level around a primary school located about 500m from the factory was as high as 1450mgkg^–1. Lead levels were equally elevated in the vegetation, though average levels in vegetation were slightly lower than in the soil. Cadmium concentrations in soil and vegetation, though low, were more positively correlated with lead levels than any of the other metals are with lead.     

Temporal variation and distribution of trace metals in freshwater and fish from Calabar River, S.E. Nigeria

An investigation on the abundance and distribution of trace metals (Fe, Cu, Zn, Mn, Cr, Cd and Pb) in water, and nine species of fish samples from Calabar river was carried out in 1992. The concentrations of iron (6000–7240gl^–1), zinc (4910–7230gl^–1), and cadmium (3–7gl^–1) showed moderate pollution while those of copper (420–630gl^–1), manganese (23–48gl^–1), chromium (<10–20gl^–1) and lead (<1–10gl^–1) in water were well below WHO permissible levels. Significant seasonal changes (0.001p0.25) were obtained for iron, copper, zinc, manganese and cadmium in water. Furthermore, iron, zinc and cadmium showed statistically significant spatial changes (0.005p0.10). Of the nine fish species studied, no statistically significant relationship between body weight and the concentrations of the metals was observed. The concentrations of the metals per mean total body weight apparently decreases in the order Fe>Zn>Cu>Mn>Pb>Cd=Cr and were within the limits that were safe for consumption.     

Grazing and ingestion rates of nauplii,copepodids and adults of the marine planktonic copepod Calanus helgolandicus

The average grazing and ingestion rates of all stages of the marine planktonic copepod Calanus helgolandicus (Calanoida) from nauplius stage IV to adults were measured experimentally at 15°C in agitated cultures. The chain-forming diatom Lauderia borealis and the unarmoured dinoflagellate Gymnodinium splendens were offered as food. The food concentrations were close to natural conditions and ranged from 36 to 101 g of organic carbon per liter. The medium body weights expressed in g of organic carbon of almost all larval stages raised at 49 g C/1 were identical with the weight of the same stages caught in the Pacific Ocean off La Jolla, California, USA. In a log-log system, grazing and ingestion rates increased almost linearly with increasing body weight. Grazing rates ranged from 4 to 21 ml/day/nauplius stage IV to 286 ml to 773 ml/day/female. Ingestion rates increased from 0.2 g to 0.8 g C/day/nauplius stage IV to 18 g to 69 g C/day/female. Grazing and ingestion rates per unit body weight decreased gradually with increasing body weight. The daily ingested amount of food decreased from 292 to 481% of the body weight (g C) of nauplius stage V to 28–85% of the body weight of adult females. Grazing and ingestion performances of all stages increased with increasing particle size. Grazing rates decreased and ingestion rates increased with increasing food concentrations. The published data on food intake of the different age groups of C. helgolandicus show that the young stages of herbivorous planktonic copepods can play a major part in the consumption of phytoplankton in the sea due to their high grazing and ingestion rates.     

Spatial mesoscale patterns of West Pacific picophytoplankton as analyzed by flow cytometry: their contribution to subsurface chlorophyll maxima

Vertical distributions of picophytoplankton (ppp) (<2 m) were studied by ship-board flow cytometry during two cruises in Western Pacific waters to Palau and to Australia in 1990. Weak red-fluorescing small ppp, supposed to be free-living prochlorophytes (Chisholm et al. 1988), were abundant in the area surveyed. These ppp, designated the prochlorophytes, were abundant in the surface waters (>10⁴ cells ml^-1) at the northern region (27°03N; 7°11N) in November, whereas in December at the southern tropical stations (0°23.54S; 9°20.30S; 13°50.6S), they formed subsurface maximum layers (>10⁵ cells ml^-1) on a nitracline at a depth of 3.5 to 5.4% surface irradiation. Their fluorescence intensity increased with depth below 10% surface irradiation. The prochlorophytes at a depth of 1% surface irradiation had ten times higher fluorescence than those at the surface layer. The total fluorescence intensity of the prochlorophytes accounted for 32 to 63% of the sum of the total fluorescence intensity of all fluorescing phytoplankton detected at subsurface chlorophyll maxima in the tropical area. These results suggest that distribution of the prochlorophytes is greatly affected by nitracline and by light intensity and that their chlorophyll is a major contributor to the subsurface chlorophyll maximum in the pelagic West Pacific Ocean.     

Two new records of Planctosphaera larvae (Hemichordata: Planctosphaeroidea)

Two specimens of the rarely found Planctosphaera larva have been taken in the North Atlantic near Challenger Bank north of the Azores and in the North Equatorial Current, latitude 19°33 N, longitude 40°01 W.This research was supported by Grant 6027-X from the U.S. National Science Fonndation and is Contribution No. 2380 from the Woods Hole Oceanographic Institution.     

Fouling organisms in the port of Mar del Plata (Argentina). I. Siphonaria lessoni: ecological and biometric aspects

The present paper deals with ecological aspects of the pulmonate gastropod Siphonaria lessoni (Blainville, 1824), a common member of fouling communities in Mar del Plata's port (38°0817 S, 57°3118 W). Populations on colonized panels of an experimental raft were studied during three annual cycles, to determine feeding habits, growth and various factors which restrict their distribution on floating substrata. Although S. lessoni is harmless as a fouling organism, its grazing on the algal belt clears a part of the substratum's surface, which is then quickly colonized by truly aggressive organisms such as Balanus amphitrite.     

The role of male vs male interactions in maintaining population dialect structure

Summary Nonmigratory populations of Whitecrowned Sparrows in coastal California exhibit dialects in territorial male songs that are stable in space and time. By field playback experiments, we tested a prediction from the hypothesis that male aggressive interactions prohibit mixing of song dialects. Playback of the home dialect Clear song to territorial males singing the Clear dialect resulted in less response than that given to playback of the neighboring Buzzy dialect. Response to both Buzzy and Clear dialect songs by target Clear males, however, was greater than that given to the Bodega dialect recorded 55 km away (Figs. 2 and 3). We conclude that these results are consistent with the hypothesis that male-male aggressive interactions play an important role in reducing dialect mixing.     

Capillary supply and mitochondrial volume density in the axial muscles of the mesopelagic teleost Argyropelecus hemigymnus

Quantitative measurements have been made on the ultra-structure and capillary supply to the axial muscles of the mesopelagic hatchet fish Argyropelecus hemigymnus (Cocco, 1829). Fish were collected at Eastern North Atlantic Ocean Station 10244, 32°48N; 31°15W during November 1980, from a depth of 480 to 550 m. Mitochondria with densely packed cristae occupy 44.3% of slow-fibre volume. Each myofibril is in direct contact with a mitochondrion. Compared with other fishes studied, the capillary supply to A. hemigymnus slow fibres is poorly developed. The average number of capillaries per fibre is 0.9, such that each m of capillary contact supplies 0.011 m² of fibre cross-sectional area. The capillary surface area (m²) supplying 1 m³ of slow-fibre mitochondria is 0.17 in anchovy (Engraulis encrasicolus), 0.14 in rat-fish (Chimaera monstrosa), 0.14 in tench (Tinca tinca), 0.16 in catfish (Clarias mossambica), and only 0.025 for A. hemigymnus. It is suggested that, relative to the former species, some modifications in factors determining tissue oxygenation (e.g. myoglobin concentrations, blood flow, perfusion distribution or haemoglobin) and/or mitochondrial respiration rate are required in order to match oxygen supply and demand to the slow muscle in A. hemigymnus.     

Dependence of consumers on macroalgal (Laminaria solidungula) carbon in an arctic kelp community: δ13C evidence

Stable carbon isotope measurements (¹³C) were used to assess the importance of kelp carbon (-13.6 to-16.5) versus phytoplankton carbon (-25.5 to-26.5) to resident fauna of an isolated kelp bed community on Alaska's north arctic coast from 1979 to 1983. The predominant kelp, Laminaria solidungula, showed some seasonal variation in ¹³C which was correlated with changes in the carbon content of the tissue. Animals that showed the greatest assimilation of kelp carbon (>=50%) included macroalgal herbivores (gastropods and chitons,-16.9 to-18.2), a nonselective suspension feeder (an ascidian,-19.0) and a predatory gastropod (-17.6). Animals that showed the least incorporation of kelp carbon into body tissues (<=7%) included selective suspension-feeders (hydroids, soft corals and bryozoans,-22.8 to-25.1). Sponges, and polychaete, gastropod and crustacean omnivores exhibited an intermediate dependence on kelp carbon (15 to 40%). Within some taxonomic groups, species exhibited a broad range in isotopic composition which was related to differences in feeding strategies. In the polychaete group alone, ¹³C values identified four major feeding habits: deposit-feeders (-18.0), omnivores (-20.4), predators (-22.2) and microalgal herbivores (-23.0). Distinct seasonal changes in the ¹³C values of several animals indicated an increased dependence on kelp carbon during the dark winter period when phytoplankton were absent. Up to 50% of the body carbon of mysid crustaceans, which are key prey species for birds, fishes and marine mammals, was composed of carbon derived from kelp detritus during the ice-covered period.     

Carbon-isotope ratio gradients in western arctic zooplankton

Zooplankton from 87 stations in the Bering, Chukchi and Beaufort Seas sampled in 1985, 1986 and 1987 showed a geographic gradient in stable carbon-isotope ratios (¹³C). The zooplankton most depleted in ¹³C were found in the central and eastern Beaufort Sea and those most enriched were from the Bering and Chukchi Seas. Average ¹³C values ranged from-20.9 to-26.7 for copepods and from-19.4 to-25.1 for euphausiids. Euphausiids show a minimum of 1.0 enrichment relative to copepods throughout the study area. Relative biomasses of the major zooplankton taxa varied significantly across the Alaskan Beaufort Sea in October 1986, with euphausiids dominating in the west and copepods in the east. These differences in taxonomic composition affected the weighted ¹³C values for total zooplankton and may produce an even more pronounced geographic gradient in zooplankton ¹³C than that found within a single taxon. The bowhead whale Balaena mysticetus migrates between wintering areas in the Bering Sea and summering areas in the Beaufort Sea and feeds over this geographic range. The zooplankton ¹³C gradient is the probable source of ¹³C oscillations found along the baleen plates of this planktivore.