Distribution of lipids between the zooxanthellae and animal compartment in the symbiotic sea anemoneAnemonia viridis: Wax esters,triglycerides and fatty acids

The temperate sea anemoneAnemonia viridis (Forskäl) contained about 11% lipid on a dry weight basis when maintained at light levels of about 10µE m^–2 s^–1 and a temperature of 10°C. Aposymbiotic forms of the anemone had similar lipid levels. These values are very low compared with tropical symbiotic Anthozoa in which lipid levels constitute up to 50% of dry weight. In symbioticA. viridis, <6% of total lipid consisted of the storage lipids, wax esters and triglycerides. Most of the triglyceride was stored in the animal tissues rather than the zooxanthellae. Zooxanthellae contained only small amounts of wax esters. An analysis was made of the wax ester, triglyceride and fatty acid composition of symbiotic anemones, isolated zooxanthellae and aposymbiotic anemones. Wax ester composition was similar in symbiotic and aposymbiotic forms. However, triglyceride composition differed. In particular trimyristin (C42) was found only within the symbiotic association. Fatty acids showed a high degree of unsaturation, and acids with both even and odd numbers of carbon atoms were found. The most abundant fatty acid was 16:0 in all samples, except for the total lipids from zooxanthellae in which the major fatty acid wastrans-18:1.     

A comparative analysis of the photobiology of zooxanthellae and zoochlorellae symbiotic with the temperate clonal anemone <Emphasis Type="Italic">Anthopleura elegantissima</Emphasis> (Brandt). III. Seasonal effects of natural light and temperature on photosynthesis and respiration

The sea anemone Anthopleura elegantissima hosts two phylogenetically different symbiotic microalgae, a dinoflagellate Symbiodinium (zooxanthellae, ZX) and a chlorophyte (zoochlorellae, ZC). The photosynthetic productivity (P), respiration (R), and contribution of algal carbon translocated to the host (CZAR) in response to a year’s seasonal ambient changes of natural light and temperature are documented for both ZX- and ZC-bearing anemones. Light and temperature both affect photosynthesis, respiration, and CZAR, as well as various algal parameters; while there are evident seasonal differences, for the most part the relative effects on P, R, and CZAR by the two environmental variables cannot be determined. Net photosynthesis (P_n) of both ZX and ZC was significantly higher during spring and summer. During these seasons, the P_n of ZX was always greater than that of ZC. Regardless of algal symbiont, anemone respiration (R) was significantly higher during the spring and summer. The annual net carbon fixation rate of anemones with ZX and ZC was 325 and 276 mg C anemone⁻¹ year⁻¹, respectively, which translates to annual net community productivity rates of 92 and 60 g C m⁻¹ year⁻¹ for anemones with ZX or ZC, respectively. CZAR did not show a clear relationship with season; however the CZAR for ZX was always significantly greater than for ZC. Lower ZX growth rates, coupled with higher photosynthetic rates and higher CZAR estimates, compared to ZC, suggest that if A. elegantissima is simply carbon limited, ZX-bearing anemones should be the dominant symbiont in the field. However ZC-bearing anemones persist in low light and reduced temperature microhabitats, therefore more than the translocation of carbon from ZC must be involved. Given that global climate change will increase water temperatures, the potential for latitudinal range shifts of both ZC and ZX (S. californium and muscatinei) might be used as biological indicators of thermal shifts in the littoral zone of the Pacific Northwest.     

Daily photosynthesis,respiration, and carbon budgets in a tropical marine jellyfish (Mastigias sp.)

From measured diel photosynthesis and respiration rates, using oxygen electrodes, estimates of carbon flux between symbiotic algae (zooxanthellae) and host animal are presented for the marine scyphomedusan Mastigias sp. from a marine lake in Palau, Western Caroline Islands, during February and March 1982. The carbon budgets calculated for these lake medusae indicate that carbon fixed photosynthetically by zooxanthellae and made available to the host may satisfy up to 100% of the host's daily metabolic carbon demand (CZAR). The stable carbon isotope (¹³C) signature of the mesogleal carbon of lake Mastigias sp. was close to that of the zooxanthellae, supporting the interpretation that while these medusae may feed holozoically, some of their carbon comes from their symbionts. The diel photosynthesis, respiration, and preliminary estimates of carbon budgets of three individuals of another ecotype of Mastigias sp. collected from nearby oceanic lagoons are also given. Photosynthesis of lagoon medusae was generally greater than that for lake medusae of similar size, and lagoon medusae were phototrophic with respect to carbon, with commensurately greater CZAR values. Carbon translocated from the symbiotic algae also may contribute to the growth requirements of both lake and lagoon medusae. From carbon flux data, the lake jellyfish were estimated to contribute about 16% to the total primary productivity of their marine lake habitat.     

Investigations of carotenoids in some fauna of the Adriatic Sea. II. Anemonia sulcata and Actinia equina (Coelenterata: Anthozoa)

Investigations have been carried out on the carotenoids in Anemonia sulcata (Pennant) and Actinia equina (L.) (Coelenterata: Anthozoa) from the Adriatic Sea. The presence of the carotenoids was determined by means of columnar and thin-layer chromatography. The following carotenoids were found: Anemonia sulcata: β-carotene, lutein-like (epoxy and free) and astaxanthin; Actinia equina: α-carotene, β-carotene, actinioerythrin, lutein-like (?) and astaxanthin (ester and free).     

Symbiont photosynthesis increases both respiration and photosynthesis in the symbiotic sea anemone Anemonia viridis

Dark respiration of the symbiotic sea anemone Anemonia viridis (Forskäl) was observed to increase by 34% when anemones were exposed to hyperoxic sea water (150% oxygen saturation) overnight, and by 39% after exposure to 6 h in the light at a saturating irradiance of 300 E m^-2 s^-1 at normoxia (100% oxygen saturation). No increase due to light stimulation was observed in aposymbiotic control anemones. In darkness, the oxygen concentration of the coelenteric fluid was hypoxic. However, within 10 min of anemones being illuminated, coelenteric fluid was hyperoxic, and it remained elevated throughout a 12 h light period. When measured over a 24 h period (12 h light: 12 h dark), the dark respiration rate increased gradually over the first 6 h of the light period until it was 35% above the dark night-time resting rate. It remained elevated throughout the remaining light period and for 2 h into the following dark period, after which it fell back to the resting rate. Gross photosynthesis (P ^gross) increased significantly when anemones were exposed to either hyperoxia (150% oxygen saturation) or 300 E m^-2 s^-1 at normoxia. This increase was not observed when symbiotic anemones were illuminated at a low-light intensity of 100 E m^-2 s^-1. The results of this study suggest that respiration in the dark is limited by oxygen diffusion and that normal respiration is restored in the daytime by utilisation of the oxygen released by photosynthesis. Furthermore, it appears that the increased respiration following exposure to high-light intensities provides a CO₂-rich intracellular environment which further enhances the photosynthetic rate of the zooxanthellae.     

Cellular and ultrastructural changes in the endoderm of the temperate sea anemone Anemonia viridis as a result of increased temperature

Exposure of the temperate sea anemone Anemonia viridis Forskål to increased seawater temperature (from 16 to 26°C) reduced the lysosomal latency of coelenterate tissues. Lysosomes in the mesenterial filaments of anemones were destabilised by increased temperature, with greater destabilisation in heat-shocked symbiotic anemones than in heat-shocked aposymbiotic anemones in the early stages of the experiment. Lysosomal enzyme activity in zooxanthellae from heat-shocked symbiotic anemones was associated with the algal membranes and the cytoplasm of degenerate algal cells. While the relationship between host coelenterate and symbiotic alga may confer many benefits under normal conditions, comparison of the responses of symbiotic and aposymbiotic anemones to heat shock suggests that there may be disadvantages for symbiotic anemones under stress.     

Metabolic responses to changing environmental conditions in the brackish water polychaetes Marenzelleria viridis and Hediste diversicolor

The metabolic strategies of the polychaete Marenzelleria viridis (Verrill 1873), a successful immigrant into Baltic shallow eutrophic coastal waters with meso-to oligohaline salinities since the 1980's, were determined by simultaneous calorimetry and respirometry. Resistance to oxygen deficiency under varying ecological conditions was also examined. The results of the studies with this immigrant were compared to those with the common indigeneous polychaete Nereis (Hediste) diversicolor (O.F. Müller). At 10 and 20 °C and the average habitat salinity of 5 M. viridis gradually reduced its metabolic activity with declining oxygen partial preessures (pO₂), whereas H. diversicolor maintained its metabolic activity. The metabolism of both species remained fully aerobic down to a pO₂ of 2 kPa. An additional hyposmotic stress of 0.5 salinity at a temperature of 20 °C led to a decrease in the rate of oxygen consumption in H. diversicolor below a pO₂ of 10 kPa, whereas metabolic heat dissipation remained constant. M. viridis, however, further reduced both, metabolic heat dissipation and oxygen consumption. The metabolic rates of both species under anoxia were similar, amounting to ca. 20% of the normoxic rate. The resistance of the two species to oxygen deficiency was also similar, ranging between 21 and 290 h (median survival time LT₅₀), depending on temperature and salinity. Specimens used in the present study were collected from the Southern Baltic coastal inlet of Darß-Zingster-Boddenkette during 1992 and 1993.     

In vitro establishment of continuous cell cultures and cell lines from ten colonial cnidarians

Continuous cell cultures from the ten taxa of sedentary colonial marine cnidariansStylophora pistillata, Porites lutea, Favia favus (Anthozoa, Hexacorallia, Madeporaria),Parerythropodium fulvum fulvum, Dendronephthya hemprichi, Nephthya sp.Heteroxenia fuscescence (Anthozoa, Octocorallia, Alcyonacea),Clathraria rubrinoides, Plexaura A (Anthozoa, Octocorallia, Gorgonacea) andMillepora dichotoma (Hydrozoa) were established in vitro. Primary cultures of various cell types (5 to 20 m) were obtained from colony fragments and/or planula larvae (collected in 1993 from coral reefs at Eilat, Red Sea and from the San Blas islands, Panama) using three dissociation approaches: a mechanical approach, chemical approach and a novel approach, spontaneous dissociation. Cells were cultured in a modified Leibowitz L15 medium, with 5 to 10% heat-inactivated fetal bovine serum, diluted in seawater. Cell proliferation was observed in primary cultures within 7 to 20 d following dissociation. When developed to secondary cultures, spindle-shaped cells (5 to 10 m) gradually replaced all other cell types seen in primary cultures ofS. pistillata, C. rubrinoides, P.f. fulvum andM. dichotoma. The spindle-shaped cells differentiated to several cell types when the diluted medium was replaced with a concentrated one, or when microbial contamination occurred. Secondary cultures of spindle-shaped cells from three species (S. pistillata, C. rubrinoides andM. dichotoma) were cloned. They gave rise to continuously proliferating cell lines (NIO-SPP-1, NIO-CR-1 and NIO-MD-1, respectively). A clone fromPlexaura planula, originated from one rounded cell, started to differentiate and gave rise to a heterogeneous culture. Samples of the above four cultures were frozen for future work. Rounded cells of various sizes (5 to 30 m) dominated secondary cell cultures ofH. fuscescence, D. hemprichi, Nephthya sp.,P. f. fulvum andF. favus. Several cell cultures fromP. lutea developed flattened cell interconnected by ectoplasmic networks characteristic of the eukaryotic unicellular organisms of the phylum Labyrinthulomycota. We propose that this culture methodology may be used as a ubiquitous protocol for producing tissue cultures from other cnidarians. The established cell lines may be used in a variety of disciplines in cnidarian biology and ecology.     

Copper uptake by the sea anemoneAnemonia viridis and the role of zooxanthellae in metal regulation

Anemonia viridis (Forskäl) were collected from south-west Scotland and south-west England in October 1988. When exposed to 0.05 and 0.2mg 1^–1 copper in sea water, anemones did not take up the metal in proportion to external concentrations. Results suggested thatA. viridis regulated copper by expelling symbiotic algae (or zooxanthellae) which were shown to accumulate copper. The use of aposymbiotic (non-zooxanthellate) anemones in similar metal-uptake experiments indicated that other mechanisms may also be involved in metal regulation. Mucus was produced byA. viridis when the anemone was exposed to copper, and it is proposed that mucus may be involved in the regulation process. The implication of this work on the use of coelenterates as biological indicators of environmental metal levels is discussed.     

An energy budget for Porites porites (Scleractinia)

An energy budget for Porites porites (Pallas) was determined for specimens from 10 m depth on the Fore Reef of Discovery Bay, Jamaica, between July 1984 and July 1985. Evidence for habitual zooplankton ingestion was not obtained, and P. porites appears to be largely autotrophic. Out of the daily photosynthetically fixed energy, 26% is used for animal respiration and growth, 22% for zooxanthellae respiration and growth, and <1% for colony reproduction as mature planulae; 45% remains unaccounted for. Colony respiration, net photosynthesis, colony skeleton and tissue growth, zooplankton ingestion, reproductive effort and energy content of tissues were measured. Energy loss as continuous mucus secretion was not detected, but may occur by an alternative route via mucus tunics, which occur periodically in situ and in the laboratory. The energy budget suggests that a considerable excess of photosynthetically fixed energy is produced on an ideal sunny day at 10 m depth. This surplus may be required for periodic rather than continuous energy demands, or may be essential to survive less-than-ideal days, when net photosynthetic input is reduced.Contribution No. 357 of the Discovery Bay Marine Laboratory, University of the West Indies     

Alloimmune memory for glycoproteid recognition molecules in sea anemones competing for space

A highly specific recognition system, capable of distinguishing between allogeneic (non-clonemates) and syngeneic (clonemates) conspecifics, exists in Anemonia sulcata (Coelenterata: Anthozoa). During a competitive interaction between allogeneic individuals, specialized structures (acrorhagi) are exposed and used to sting opponents. This complex behavior is called the acrorhagial response. In order to quantify this behavior we measured the acrorhagial response time (period from first contact with opponent to full expansion of acrorhagi). More than 320 reciprocal histoincompatibility responses were recorded. These histoincompatibility (H) markers are free components of the sea anemone mucus: they were characterized as glyco-proteins of a molecular weight <18 KD (Kilo-Dalton) containing terminal -d-glucose and/or -d-mannose. In alloimmune memory testing experiments, the memory trace in A. sulcata was found to persist for 5 d.     

Permeability of the oral epithelial layers in cnidarians

In order to characterize the permeability of the oral epithelial layers in cnidarians, we investigated the kinetics of transport of labelled ions (⁴⁵Ca,²²Na,³⁶Cl) and organic molecules (¹⁴C-inulin-carboxyl,¹⁴C-ala) through the oral tissue of two cnidarian species,Anemonia viridis (Forsskål, 1775) andHeliofungia actiniformis (Quoy and Gaimard, 1833) using the Ussing chamber method. In both species, unidirectional Ca, Na and Cl fluxes were the same in both directions (ectoderm towards endoderm and vice versa), the net flux being equal to zero. The insensitivity of these unidirectional transepithelial fluxes to metabolic inhibitor (1 mM sodium cyanide) and calcium channel inhibitor (100 M verapamil) and their linear dependence on calcium concentration suggest that these fluxes are simple driven by diffusion via a paracellular pathway. The epithelial layers were not permeable to inulin. Low-molecular weight amino acids such as alanine did not cross the epithelia but were absorbed by the ectoderm. The permeability coefficients indicate that the oral epithelial layers are leaky. It is suggested that the coelenteric cavity represents a compartment in which the ionic pool can be entirely renewed by simple diffusion. This process seems efficient enough to meet all calcium requirements in scleractinian corals.     

Relationships between porewater nutrients and seagrasses in a subtropical carbonate environment

The feeding, diet and egg production of the copepod Acartia tonsa were dermined during ten experiments in Los Angeles Harbor, California, between November 1986 and October 1987. Copepods were incubated in situ, in quasi-natural food environments. Water temperatures ranged from 14.6 to 21.5°C. Particulate organic carbon and nitrogen (POC and PON) were high (534 to 3710 g Cl^-1, 51 to 459 Nl^-1) but dominated by small (<8 m diam) particles. Plankton (phytoplankton and microzooplankton) C-biomass composed about 10% of the total POC and was usually dominated by particles >8 m. Plankton biomass was always low. Daily ingestion rates ranged from 3 to 96% of body C; egg production ranged from 4 to 35% of body carbon. Mean ingestion and egg production rates during spring-summer were 1.9 and 1.5 times higher than average for the entire study, respectively. The average gross efficiency of egg production for the study was 80%; the spring-summer mean was 41%. Bivariate and multiple-regression analyses revealed that the ingestion rate was dependent upon both temperature and food availability, but that, below 21°C, egg production depended more upon temperature than upon food concentration. To detect dietary preferences, the composition of diet was compared with that of the food supply. Selective feeding was infrequent, but the diet was often dominated by dinoflagellates and ciliates. It would appear that within metabolic limits governed by temperature, the feeding response of A. tonsa is dependent upon food concentration, while egg production depends more on qualitative attributes of the food supply.     

Effect on fishes of two toxic polypeptides isolated from Anemonia sulcata

The effects of two toxic polypeptides isolated from Anemonia sulcata Pennant (Anthozoa) were tested on Gadus morhua, Pleuronectes platess and Platichthys flesus. In tramuscular injections caused paralysis and death, with symptoms similar to those of death caused by lack of oxygen. In cod, the LD₅₀ dose of Toxin II was 50 times higher chan that of Toxin I (Toxin I=6.9 mg/kg, Toxin II=0.14 mg/kg). Flatfish were less sensitive. The LD₅₀ of Toxin II was 0.37 mg/kg for Platichthys flesus and 0.38 mg/kg for Pleuronectes platessa. Both toxins are less lethal to fishes than to crustaceans.     

Nutrition studies in the nauplius larva of Calanus pacificus (Copepoda: Calanoida)

Nauplii of Calanus pacificus were raised on a mixture of algae. Details of the mouth-parts, such as denticles, labial palps and lobes, setations and structure of the masticatory teeth were examined by scanning electron microscopy (SEM). Under the experimental conditions (15°C and 300 gC l^-1), exponential growth coefficients for the period Nauplii II–VI were 0.179 for carbon and 0.228 for nitrogen. C:N ratios dropping from 5.1 to 4.7. Growth was isochronous, each stage lasting 1.5 days. Respiratory losses were 15 to 19.6% of body carbon daily. Nauplii raised on a given alga showed higher rates of ingestion in the presence of this food, compared to nauplii switched to other algae. Minimal threshold concentrations for feeding were found, depending on the size of the food offered and ranging from 5.8 gC I^-1 for Lauderia borealis (28.7 m spherical diameter) to 47.1 gC 1^-1 for Chlamydomonas sp. (11.0 m). Unlike the Copepodite I stage, Nauplii II–VI larvae were not able to ingest small cells such as Isochrysis galbana (4.3 m), or very large ones such as Ditylum brightwellii (47.5 m) at more than maintenance rations. Below the critical concentration for maximal feeding, ingestion was clearly dependent on size of the cells offered, but the size-dependent relationship was different for diatoms and non-diatoms. Filtering rates increased from a threshold concentration to a maximal rate at about 50 gC 1^-1, and decreased at higher concentrations. Critical concentrations ranged from 125 gC 1^-1 for L. borealis to 1000 gC 1^-1 for Chlamydomonas sp. Maximal daily rations ranged between 100 and 150% of body carbon.     

Sea-water temperature and spawning behaviour in the seastar Marthasterias glacialis

The seastar Marthasterias glacialis (L.) was seen to spawn in two sea inlets, Lough Hyne (9°18W; 51°30N) and Mulroy Bay (7°42W; 55°12N), Ireland. Spawning occurred during the afternoon and early evening between 13.30 and 21.30 hrs British Summer Time (BST) on sunny days during July and August, 1978. Groups remained assembled for days prior to spawning. Solitary and grouped seastars arched themselves and released their gametes freely. Local moderate onshore winds on sunny days resulted in increases of sea temperature which often induced spawning. Males observed spawning ranged from 2.5 to 26 cm and females from 9 to 22 cm in diameter over the period 1978–1985.     

Spring and summer growth rates of subarctic Pacific phytoplankton assemblages determined from carbon uptake and cell volumes estimated using epifluorescence microscopy

In order to determine whether phytoplankton growth rates were normal or depressed, total plant carbon (g l^–1) and in situ production rates (g C l^–1 d^–1) were measured for phytoplankton assemblages at Weathership Station P (50°N; 145°W) and at 53°N; 145°W in the subarctic Pacific in May and August 1984. Plant carbon, estimated from cell volumes determined using epifluorescence microscopy, was distributed as follow: 28% in the <2 m fraction, 38% in the 2 to 5 m size fraction, and the remainder in size classes >5 m. Carbon-specific growth rates (k), as doublings d^–1, were calculated for the phytoplankton assemblages as a whole at each sampling depth down to 100 m for three days in May and for four days in August. The populations in the upper part of the euphotic zone showed average doubling rates of 1 d^–1 and thus appeared to be growing at rates normally expected for the prevailing conditions of light and temperature. The low chlorophyll concentrations (0.3 to 0.4 mg chl a m^–3) characteristically found in this oceanic region do not seem to be due to very slow growth of algal populations.Contribution No. 1695 of the School of Oceanography, University of Washington, Seattle, Washington 98195, USA     

Importance of refractory plant material to the carbon budget of the oyster Crassostrea virginica

The ability of the oyster Crassostrea virginica (Gmelin) to filter, ingest and assimilate ¹⁴C-labeled Spartina alterniflora as a carbon source was investigated under laboratory conditions. The oyster assimilated crude-fiber carbon extracted from S. alterniflora with an efficiency of approximately 3%. Enteric bacteria did not enhance this process. The annual average (April 1984 to November 1985) of crude fiber in the Choptank River sub-estuary of the Chesapeake Bay, Maryland, USA, from which the oysters were collected, was 15.7 g l^-1 (range 4.3 to 34.3 g l^-1). The potential food value of crude fiber to oysters in this system was estimated to be less than 1% of their carbon demand. However, the potential contribution of crude fiber to the carbon requirements of other oyster populations, such as those in southeastern USA, may be as great as 20%, due to higher crudefiber concentrations in the seston.     

Phytoplankton exudate release as an energy source for the growth of pelagic bacteria

The release of dissolved organic carbon (DOC) from phytolankton during photosynthesis, and the utilization of this carbon by planktonic bacteria, was studied using ¹⁴CO₂ and selective filtration. Natural sea water samples from a coastal area of the Northern Baltic Sea were incubated in the laboratory for detailed studies, and in situ for estimation of annual dynamics. In a laboratory incubation (at +1°C) the concentration of ¹⁴C-labelled dissolved organic carbon increased for about 2 h and then reached a steady state, representing about 0. 1% of the total DOC. Labelled organic carbon in the phytoplankton and bacterial fractions continued to increase almost linearly. The continuous increase in the bacterial fraction is thought to represent almost instantaneous utilization of the DOC released from the phytoplankton during photosynthesis. As an annual average, in 4 h in situ incubations, about 65% of the labelled organic carbon was found in the phytoplankton fraction (>3 m), about 27% in the bacterial fraction (0.2 to 3 m) and the remaining 8% as DOC (<0.2 m). Large variations in these percentages were recorded. The measured annual primary production was 93 g C m^-2 (March to December), and the estimated bacterial production due to phytoplankton exudates 29 g C m^-2. This represents a release of DOC of about 45% of the corrected annual primary production of 110 g C m^-2 (assuming a bacterial growth efficiency of 0.6).     

Observations in captivity of the activity patterns and resources utilization of the spider crab <Emphasis Type="Italic">Inachus phalangium</Emphasis> (Decapoda,Majidae)

The spider crab Inachus phalangium is common in the sublitoral fringe of the Mediterranean Sea and north-eastern Atlantic Ocean, where it can be found in association with the snakelocks sea anemone Anemonia viridis. Studies concerning its activity patterns and the role of the host sea anemone are lacking. Our study aimed at investigating activity rhythms and resources utilization of I. phalangium reared in captivity. The main behavioral traits exhibited by I. phalangium are performed mostly at night. Two experiments were designed, one examined the time budget of various behavioral acts and the degree of association with the sea anemone, the other analyzed the behavioral response to algae and anemones. We showed that algae have a crucial role in the biology of I. phalangium and that crabs are ready to leave the protection of their host to obtain them. Algae represent both the major component of the diet and one of the most utilized sources of masking material of I. phalangium, which provide, together with specialized cryptic behaviors, protection against predators. Although our data suggest that the association with A. viridis is not obligatory, but the role of the snakelocks sea anemone in the life of I. phalangium is still central, both as an anti-predatory defense and as a nutritional source. The association of I. phalangium with algae and the anemone is a facultative biotrophic commensalistic symbiosis.