A Sponge-Eating Worm from Bermuda: Branchiosyllis oculata (Polychaeta,Syllidae)*,†

Abstract. Branchiosyllis oculata is a small, errant polychaete that lives only on the surface of sponges: among inshore Bermudian sponges, 9 out of 16 species surveyed were infested. All of these sponges were conspicuously colored, but the bodies and gut contents of associated polychaetes matched the sponge color only for Tedania ignis (red), Cinachyra alloclada (yellow) and Sphecio-spongia othella (brownish-black). For the remaining 6 sponge species, the polychaete bodies were uncolored and the polychaete gut contents were inconspicuously brown or grey. Uncolored polychaetes with grey gut contents were removed from a dark green Tethya actinia and placed on a red Tedania ignis: 2 days later, the polychaete gut contents were red, although the tissues were still uncolored. Acetone extractions of Tedania ignis and Cinachyra alloclada were prepared from sponge tissue and from the gut-free tissue of their respective polychaetes: absorption spectra matched for each sponge/polychaete pair. To test the influence of ingested sponge pigments on polychaete body color, red polychaetes from Tedania ignis were induced to autotomize their posterior ends, transplanted to other sponge species and allowed to regenerate new posterior segments for 20 days. At the end of the experiment the original segments were still red, but the regenerated ones were either yellow (for polychaetes transplanted onto Cinachyra alloclada, on which resident worms are yellow) or colorless (for polychaetes transplanted onto Chondrilla nucula or Tethya actinia, on which resident worms are uncolored). The foregoing observations suggest that (1) the polychaetes consume the soft parts of the sponges on which they live and (2) the pigments vary among sponge species: pigments from some sponges are stored in the polychaete body, while pigments from other sponges are not. Additional information on the morphology, distribution and natural history of Branchiosyllis oculata is presented and discussed.     

Seasonal Analysis of Zoobenthos Associated with a Zostera marina L. Bed in Gulbahce Bay Aegean Sea, Turkey

Abstract. seasonal sampling of three stations in Gulbahce Bay Aegean Sea for the zoobenthic organisms associated with a Zostera marina bed was carried out during 1993–94. Temperature, salinity and oxygen were recorded each sampling period. A total of 7 taxonomic groups were determined: Polychaeta was the dominant group comprising 77 % of the total taxa and individuals, followed by Crustacea, Bivalvia and other groups such as Nemertea. Sipuncula, Turbellaria and Phoronida. Of the 108 taxa encountered, the polychaetes Notomastus latericeus and Caulleriella alata accounted for 49 % of the total populations. The species abundance did not show major changes among seasons, with highest values in fall 982 indiv. ·m^-2 and lowest in spring 754 indiv. ·m^-2. Diversity and evenness of the samples were relatively high and fairly constant, and were affected by the dominance levels of the species.     

Nutrients, Chlorophyll a and Phytoplankton in the İskenderun Bay (Northeastern Mediterranean)

Abstract. The monthly changes in chlorophyll a , phytoplankton abundance and nutrient concentrations at two stations, one at the inshore and the other at the deep waters of the northern part of İskenderun Bay, were investigated between 1994 – 1995. The vertical distribution of nutrients and phytoplankton biomass were also studied at the deep station. The concentrations of NO₃+NO₂-N, PO₄-P and SiO₄-Si of surface water at both stations were 0.31 – 1.63 µg-at · l^-1, 0.08 – 0.60 µg-at · l^-1 and 0.50 – 2.7 µg-at · l^-1, respectively. The highest concentrations were measured at the inshore station and clear differences were found between the inshore and deep-water stations. Chlorophyll a concentrations ranged from 0.17 to 2.78 µg · l^-1 and the highest value was measured in March. At the inshore station, which was affected by land run-off, phytoplankton abundance reached the highest value (21,308 cells · l^-1) in October 1995, with a marked dominance of Pseudonitzschia pungens (20,200 cells · l^-1). The nutrient and chlorophyll a concentrations at the inshore station were higher than those at the deep station. One reason for this is the land-based nutrient input into the coastal area here. In spite of these effects, the bay is not eutrophicated because of circulation events in the northeastern Mediterranean.     

Population Density, Distribution and Consumption Rates of Three Corallivores at Cabo Pulmo Reef, Gulf of California, Mexico

Abstract. The influence of corallivores on coral community structure of eastern Pacific reefs has been considered less important then that of abiotic oceanographic factors. The data that support this assumption, however, are only available for Central American reefs. To assess the role of predation on hermatypic corals in a different regional reef environment, the abundance, spatial distribution and consumption rate of three corallivores: the echinoid Eucidaris thouarsii (Valenciennes), the asteroid Acanthaster planci (Linnaeus) and the teleostean fish Arothron meleagris (Bloch & Schneider), were estimated at Cabo Pulmo reef, Gulf of California, México (23°25' N, 109°25' W). Statistically, the abundances of the species did not change in any sections of the reef (mean values: E. thouarsii , 0.17 indiv. · m⁻²; A. planci , 1.9 indiv. · m⁻²; A. meleagris , 39 indiv. · ha⁻¹). The average daily individual consumption rates of coral were calculated at 1.83 g CaCO₃· m⁻² for E. thouarsii , 118.4 cm² for A. planci , and 16.38 g CaCO₃· m⁻² for A. meleagris , and were lower than those reported for Central American reefs. Considering the mean estimated carbonate production (7.9 kg CaCO₃· m⁻²· a⁻¹), corallivores eliminate less than 4% of the coral standing stock of Cabo Pulmo reef. The low corallivore population density and consumption rates, together with high local coral cover, indicate that corallivores are not key factors determining scleractinian abundance in this marginal reef.     

The Importance of Posidonia oceanica and Cymodocea nodosa as Contributors of Free Amino Acids in Water and Sediment of Seagrass Beds

Abstract. Dissolved free amino acids (DFAA) were measured in sediment porewater and overlying sea water in seagrass beds of Posidonia oceanica and Cymodocea nodosa at a water depth of 8–10 m in Corsica, France. In the sea water, DFAA concentrations from 0.5 to 1.9μM were found. Lowest concentrations occurred in the afternoon in surface water samples, while higher concentrations were measured in morning surface samples and in all bottom samples. The most abundant amino acids were serine, glycine, and alanine. In the sediment, the upper 4cm contained the highest concentrations of DFAA (177nmol cm^-3 or 367 μM), while lower concentrations (<50nmol cm^-3 or 104 μM) prevailed deeper in the sediment. Glycine, glutamic acid, alanine, and β-alanine were the major components of the DFAA. The photosynthetic activity of the seagrasses influenced sediment porewater pools of DFAA. When a Posidonia bed was covered with a black polyethylene shield, the interstitial amino acids were reduced at a rate of 16nmol cm^-2 h^-1 (0-10cm depth). Conversely, extended daylight (floodlight) increased the DFAA pool in sediment depths below 4 cm. Free amino acids were released to the overlying sea water from both seagrass sediment and individual shoots, the rates being highest in the dark. The present investigation indicates that a substantial portion of the N-cycling of the seagrass sediment includes free amino acids.     

Primary Production and Growth Dynamics in Posidonia oceanica

Abstract. Studies on leaf growth and production were performed in two stands, at depths of 5 m and 22m, in the Posidonia oceanica (L.) D elile bed off Lacco Ameno, Ischia (Gulf of Naples). Experiments were carried out in situ from May 1988 to August 1989 at monthly intervals.
Leaf growth and production profiles differed in the two stands investigated. Growth rates were higher at 5 m, with a peak in autumn (5.8 mg · shoot^-1· d^-1) and another in March (3.8 mg · shoot^-1· d^-1). At 22 m the maximum rate occurred in May (3.9 mg · shoot^-1· d^-1). These differential growth rates resulted in a delayed maximum leaf surface and biomass at the deep stand, where lower irradiance values and different temperature patterns were also found. The biomass of epiphytic algae showed trends similar to those of leaves; however, there were remarkable differences in the values between the two stations and for the two investigated years.
The production data of the present study are compared with those of other reports, and it is shown that growth processes are greatly influenced by physical factors.     

The sandy beach macrofauna of Gulf of Gabès (Tunisia)

This study describes the macrofauna of the three beaches situated in central Gulf of Gabès (Tunisia): Ouderef, Gabès and Zarrat. The Gulf of Gabès has the largest tides in the Mediterranean and the beaches showed a wide intertidal zone. The beaches were sampled once during the spring low tides of June 2005. A transect was extended at each beach, from above the drift line to below the swash line at five sampled levels; at each level six 0.05 m² replicates were taken to a depth of 30 cm and sieved through a 1-mm mesh, and the organisms collected and preserved. The three beaches showed a different physical environment. Sediment type was medium sand at the steeper Ouderef beach, fine sands at Gàbes beach, and very fine sands at the flatter Zarrat beach. The total number of species collected was 31: 12 crustaceans, 10 polychaetes, four molluscs and five insects. The supralittoral and mediolittoral zones were very different. The supralittoral zone was dominated by Talitrus saltator and insects. The most abundant mediolittoral species were the amphipod crustacean Bathyporeia guilliamsoniana at Ouderef beach (23069 ind.m⁻¹), the surf clam Donax trunculus at Gabès beach (60711 ind.m⁻¹) and the spionid polychaete Scolelepis mesnili at Zarrat beach (18345.6 ind.m⁻¹).     

Respiratory Rate and Assessment of Secondary Production in the Holothuroid Holothuria tubulosa (Echinodermata) from Mediterranean Seagrass Beds

Abstract. Respiration in Holothuria tubulosa was investigated in individuals from the Posidonia oceanica meadow off Lacco Ameno (Ischia Island, Italy). Respiratory rates increase with increasing body weight and increasing sea water temperature. Oxygen consumption of an average individual (7g dw body wall) ranges from 0.409 (14 °C) to 1.300 (26 °C) mg O₂· h^-1. Data on population density, mean size of individuals, and annual sea water temperature variations allow an assessment of holothuroid production. Values of 45.65 and 13.75 kJ · m^-2· y^-1 were calculated for shallow (3 to 10 m) and deep (25 to 33 m) areas of the Posidonia meadow, respectively. Holothuroid production shows a bathymetric pattern similar to primary production of the Posidonia -epiphytes complex and the production of Posidonia litter.     

Polychaete Fauna of Seagrass Beds (Halodule wrightii Ascherson) Along the Coast of Rio de Janeiro (Southeast Brazil)

Abstract.  The polychaete community structure from six Halodule wrightii seagrass beds along the Rio de Janeiro coast (Southeast Brazil) was investigated. Variations in species diversity, overall density and species composition in relation to sediment grain size, seagrass biomass and selected plant structural features such as root and shoot length from the study sites were analysed. Ten core samples (0.02 m²) were randomly collected from each site. Three additional samples were taken for grain size analysis of sediment. Sixty-eight species of polychaetes belonging to 24 families were found. The dominant species as well as species composition varied greatly among sites, showing that a typical polychaete community does not exist. The number of species was positively correlated with the silt-clay percent and sorting coefficient of the sediment. A positive correlation between polychaete density and plant biomass was also obtained. Multivariate analysis indicated that polychaete communities were influenced greatly by seagrass plant features: plants with longer shoots harbour mainly surface-deposit feeders such as Magelona papillicornis , whereas plants with a higher root-shoot length relation sheltered mainly suspension or interface feeders like Fabricia filamentosa . This study demonstrates that granulometric properties as well as plant architecture play an important role in structuring the polychaete community. As the community-level response can reflect changes in local seagrass beds, the structure of the polychaete community can be an important indicator for management plans and the restoration of seagrass ecosystems.     

Production of Domoic Acid by Pseudo-nitzschia multiseries Hasle, Affected by Lithium

Abstract. Upon enrichment with lithium 385.6 μM Li, culture of Pseudo-nitzschia multiseries H asle produces substantially higher level of the neurotoxin domoic acid DA 230 fg · cell^-1 than the control 135 fg · cell^-1. We hypothesize that in Cardigan Bay, where the first domoic acid episode was reported, high levels of Li could have originated via a massive freshwater run-off involving an adjacent dump. Lithium enrichment may have played a part in enhancing DA production leading to the intoxication episodes of 1987. Thus, anthropogenic activities may play a role as a sustainer of algal blooms and should be included in habitat management considerations involving coastal and inshore algal blooms, both toxigenic and non-toxigenic.     

Benthic Fluxes of Dissolved Inorganic Nitrogen in a Coastal Lagoon of the Northern Adriatic Sea: an Interpretation of Spatial Variability Based on Sediment Features and Infauna Activity

Abstract. Dark respiration rates, dissolved inorganic nitrogen (DIN) fluxes and nitrification rates were measured at two sites in the microtidal Sacca di Goro lagoon in September 2000. DIN fluxes correlated with the biomass of the dominant macrofauna species (the amphipod Corophium spp. at station Giralda and the polychaete Neanthes spp. at station Faro). Respiration (> 6 mmol O₂ m⁻²h⁻¹) and ammonium fluxes (> 80μmol N m⁻²h⁻¹) were higher at station Giralda despite the lower organic matter content (4.5 %) and lower macrofauna biomass (4 g AFDW m⁻²). At both sites ammonium fluxes were significantly correlated with the biomass of the benthic infauna, but Corophium stimulated ammonium NH₄⁺ fluxes 3-fold compared to Neanthes. The amphipod also enhanced nitrification rates (> 300 μmol N m⁻²h⁻¹) due to the high density of its burrows, the higher NH₄⁺ regeneration rates and the enhanced oxygen supply to the bacteria.     

Feeding of the Sparid Fish Sarpa salpa in a Seagrass Ecosystem: Diet and Carbon Flux

Abstract. In Revellata Bay Gulf of Calvi, Corsica, France, the sparid fish Sarpa salpa L. is the main macro-consumer of Posidonia oceanica L. D elile leaf. Stomach contents were analysed and ¹³C/¹²C isotopic ratios were measured in fish muscle and potential food sources algae, P. oceanica leaf and its epiphytes to determine their relative contribution to the fish diet. S. salpa has an age-related mixed diet: juveniles are plankton feeders, young, sub-adults and adults are herbivorous, and, the older the individuals, the higher the relative contribution of P. oceanica to the diet. Our results and former studies of carbon stocks and fluxes in the P. oceanica bed of Revellata Bay have enabled an estimation of the general impact of S. salpa grazing on infralittoral communities: the studied species consumes 24 g C.m^-2 -a^-1 from P. oceanica leaf, 4.8 from epiphytes and 13 from epilithic algae. The fish net production and biomass turnover in that zone have been estimated to be 1.2gC.m^-2.a^-1 and 1.5 a^-1, respectively.     

Habitat Selection and Ecology of Two Speleophilic Gobiid Fishes(Pisces: Gobiidae) from the Western Mediterranean Sea

The life habits and microhabitat selection of speleophilic gobiid fishes were investigated on the Balearic Island of Ibiza (western Mediterranean Sea). Corcyrogobius liechtensteini (Kolombatović, 1891) was the most frequent species within submarine crevices, cavities and caves. Didogobius splechtnai Ahnelt & Patzner, 1995 co-occurred with C. liechtensteini in several cases but showed a clear spatial separation based on a different microhabitat preference. The microhabitat selection of both species was confirmed by habitat-choice experiments in anaquarium. Corcyrogobius liechtensteini was frequent in depths between 5 m and 25 m and attained abundances of 14.2 individuals · m⁻². This species inhabited the ceilings and upper parts of the walls within the caves. D. splechtnai was mainly found between 7 m and 11 m and showed abundances of approximately 2 indivi-duals · m⁻². This species occupied the fine sediment bottoms in the innermost parts of crevices and caves. The growth and the maximum age of both species were determined by length-frequency distributions. The overall sex ratio from catches of three different years are given for C. liechtensteini .     

Polychaete Assemblages in the San José Gulf (Chubut, Argentina), in Relation to Abiotic and Biotic Factors

Abstract. The composition and distribution of the polychaete assemblages of the San José Gulf (Chubut, Argentina) are described in relation to environmental variables using indicator species (TWINSPAN) and canonical correspondence analysis (CCA). The polychaetes were collected during a benthic cruise in October 1984. Sediments were collected at 110 sampling sites using a 0.25 m² van Veen bottom grab or by divers in near-shore areas and sieved with 1 mm mesh. A total of 73 polychaete taxa were collected and identified. Both analyses revealed the presence of four main assemblages distributed according to depth as well as bivalve and seaweed abundance gradients: ' Syllis-Eunice ' and ' Harmothoe-Eunice ' assemblages occurred at the same depths (0 –­ 185 m) and substrata (poorly sorted rock and coarse sand), but were separated by bivalve and seaweed abundance, wherby the highest abundances of bivalves and the minimum abundances of seaweeds corresponded to the ' Syllis-Eunice ' association. The ' Ninoe-Glycera ' and ' Aglaophamus- Fabriciinae indet. 6' assemblages also occurred at similar depths (0 – 60 m) and substrata (very well-sorted medium-fine sand), but differed in their composition of bivalves and seaweed abundances; the ' Aglaophamus- Fabriciinae indet. 6' association corresponded with minimum bivalve and maximum seaweed abundances.     

Diel Activity Patterns and Foraging Dynamics of the Sea Urchin Tripneustes ventricosus in a Tropical Seagrass Community and a Reef Environment (Virgin Islands)

Abstract. Feeding and movement activity patterns and the foraging behavior of the sea urchin Tripneustes ventricosus were investigated in a Thalassia testudinum seagrass bed and on a patch reef at St. Croix, U.S. Virgin Islands.
Most of T. ventricosus in the seagrass bed fed during both the day and night. Consumption of seagrass blades amounted to 1.4 g dw · individual^-1· d^-1 (mean sea urchin size 12.1 cm ambitus diameter). The population consumed approximately 3.6% of the daily seagrass production.
The movement of T. ventricosus was diel with high nocturnal activity levels and rates of locomotion, and little activity during daylight hours. Foraging activity was reduced under turbulent conditions. Movement rates were not governed by food availability. T. ventricosus travelled 3.7 m · d^-1 on the patch reef. Individuals in the seagrass bed moved 8.8 m · d^-1, most of which was accomplished during the night. The area traversed contained more than one hundred times the amount of food consumed daily. It is assumed that this behavior requires high energy expenditures for locomotion, thus yielding a low net energy profit from feeding.
The high rate of movement in seagrass beds may represent an innate behavioral adaptation to predation by night-active helmet conchs ( Cassis spp.). Fitness optimization by T. ventricosus may have been achieved by minimizing the predation risk during night hours. In an evolutionary context, survival by means of an increased energy expenditure for locomotion may compensate for the lower net energy gain from foraging.     

泉州湾及其附近海域底栖多毛类生态的初步研究

本文用2001-2002年泉州湾及其附近海域综合调查中获得的底栖多毛类资料,探讨该海域多毛类的组成、数量分布及与环境因子的关系.共鉴定出该海域多毛类68种,多数属亚热带海区常见种,其中双鳃内卷齿蚕为主要的优势种.多毛类年平均栖息密度和生物量分别为56个/m^2和1.11 g/m^2,数量分布不均匀,下洋附近海域为主要的高栖息密度和高生物量区.沉积物类型显著影响多毛类的数量分布,而底层海水的温度和盐度对其也有一定的影响.     

Distribution patterns of interstitial polychaetes in sandy beaches of southern Brazil

This study describes the distribution patterns of interstitial polychaetes along morphodynamic gradients on six exposed sandy beaches in Santa Catarina and Paraná (South Brazil). Three random transects were sampled at two points on each beach, one at the swash and another at the surf zone, in winter and summer conditions. Six sediment replicates were collected at each sampling point using a corer of 4.6 cm internal diameter that removed 10 cm into the sediment. Abundance and composition of interstitial polychaete were correlated to wave height, slope, grain size, CaCO₃, chlorophyll a , omega indexes, temperature and relative tide range using a canonical correspondence analysis (CCA). A factorial ANOVA showed that taxa richness, mean density and Shannon's diversity were significantly higher at the reflective beaches, but average values differ significantly between transects and these differences change according to the beach zones on both sampling dates. PERMANOVA showed that polychaete associations differ among transects according to the beach zones. The composition of interstitial polychaete associations was significantly correlated to beach morphodynamics and features (P < 0.01). Polychaete associations of reflective beaches were more diverse than in other morphodynamic states. Intermediate beaches may also sustain diverse associations due to temporal variability of the morphodynamic patterns. Beaches presenting extreme dissipative morphodynamics and compacted sediments appear to be unfavourable for the occurrence of interstitial polychaetes.     

Production of the Crab Elamenopsis kempiHymenosomatidae in the Garmat-Ali Region, Basrah, Iraq

Abstract. The production of the hymenosomatid crab Elamenopsis kempi was calculated for a period of 18 months from a subtidal area of the Garmat-Ali river, southern Iraq. The highest average individual somatic energy was attained in spring. Maximum population biomass and production were attained by the summer cohort and the minimum values were exhibited by the overwintering cohort. The fluctuations of the average population biomass were followed throughout the sampling period. Average total annual population production was 13.2 g DW · m^-2· a^-1 and the P/B ratio was 5.9. These values were compared with those of the most common crustaceans in the region.     

Stock Evaluation of Three Littoral Echinoid Species on the Catalan Coast North-Western Mediterranean

Abstract. We estimated the abundances of the three common littoral echinoid species Paracentrotus lividus, Arbacia lixula and Sphaerechinus granularis in a littoral zone between 0 and 10m depth on the Catalan shores NE Spain. Densities of each species were estimated from a total number of 11 571× 1 m² sampling units deployed at 152 sites along the 13 zones into which the coast was divided. The surface area available in each of these zones was estimated at the scale of the sampling unit 1 m² taking into account the fractal dimension of the shore. The stocks individuals > 2cm test diameter of these species for the whole Catalan shore ≅ 300 km, straight-line distance were estimated to be about 279.1 × 10⁶ individuals for P. lividus , 28.9 × 10⁶ individuals for A. lixula and 10.9 × 10⁶ individuals for S. granularis. These sea-urchins are key species in the regulation of algal communities and some of them P. lividus. S. granularis are of commercial interest. This information will provide a tool for the future monitoring and management of this resource, which now faces diverse pressures of human origin.     

Sponges Inhabiting a Mediterranean Red Coral Population

Abstract. A coastal red coral [Corallium rubrum (L.)] population, whose age structure and demographic parameters have been previously analysed, harbours 10 species of endobiotic sponges. This sponge assemblage differs considerably from that inhabiting other calcareous substrata of the surrounding area, suggesting some selectivity for red coral. The two most common endobiotic species, Spiroxya heteroclita T opsent and Cliona sarai M elone , are described in detail. The percentage of infested coral colonies increases according with colony age, with a sharp increment at four years. An increase in coral colony mortality observed at this age may be related to the increment of endobiotic sponge infestation.