Metabolism of shallow and deep-sea benthic crustaceans and echinoderms in Hawaii

Little is known about the metabolism of deep-living, benthic invertebrates, despite its importance in estimating energy flow through individuals and populations. To evaluate the effects of depth and broad taxonomic group/locomotory mode, we measured the respiration rates of 25 species of benthic decapod crustaceans and 18 species of echinoderms from the littoral zone to the deep slope of Hawaii. Specimens were collected by hand, trap, or submersible and maintained in the laboratory at temperatures close to ambient temperatures recorded at the time of collection. After acclimatization to laboratory conditions, oxygen consumption was measured for each individual in closed chambers. Overall, crustaceans had higher metabolic rates than echinoderms, and within the crustaceans, caridean shrimps had higher rates than crabs and lobsters. These differences are probably related to locomotory mode and general levels of activity. At in situ environmental temperatures, metabolic rates of deeper-living invertebrates are much lower than those of shallower living species, but this decline is explained by changes in temperature. When the data were compared with similar data sets collected off California and in the Mediterranean, Hawaiian crabs, lobsters, and echinoderms had lower metabolic rates than similar species in the other regions after adjustments for temperature were made. Some of these differences could be methodological. Regional food web models should use broad taxonomic groupings and region-specific data when possible.     

Role of microorganisms and macrofauna in benthic phosphorus dynamics in the po river--Adriatic Sea frontal system: An experimental approach

Sediment biotic and abiotic attributes were determined during the PRISMA II oceanographic campaigns in the northern and central Adriatic Sea. The radiotracer orthophosphate 32 P was used under laboratory conditions to analyse the role of micro- and macrofauna in phosphorus dynamics at the water-sediment interface. Effects of infaunal suspensivores on microfungal growth were also investigated. Our findings emphasised: 1) significant differences in sediment 32 P uptake as related to the sampling area, occurrence of the pelagic frontal system, sediment grain size, microbial activity, and anoxia; 2) the crucial role played in 32 P dynamics by different tropho-functional groups r - r i.e ., infaunal filter-feeders and epifaunal detritivore characterising the benthic community of the northern Adriatic basin. The significant changes in ergosterol concentration (adopted as an index of microfungal growth) observed in sediments subjected to infaunal activity, eventually provided a comprehensive insight into macrofauna-microorganism interactions. The potential impact of macrofaunal activity in phosphorus dynamics in the Adriatic benthic system is discussed.     

Ecology and distribution of the benthic fauna in the shallow waters of the Red Sea

Approximately 500 animal species and plants are listed as being the most typical for the infratidal and shallow subtidal benthic fauna of the Red Sea. Most of them are divided into communities typical for various soft and hard substrata, and at different water depths. The oceanographic conditions and the development of several of the communities are discussed in general terms.Supported partly by grants 62558-4556 and F 671052 67C 0043 of the US Office of Naval Research and Grant SFC-7-0074 of the Smithsonian Institution.     

Microplastics in the benthic invertebrates from the coastal waters of Kochi,Southeastern Arabian Sea

This study examined microplastic particles present in the benthic invertebrates Sternaspis scutata, Magelona cinta (deposit feeders) and Tellina sp. (suspension feeder) from the surface sediments of off-Kochi, southwest coast of India. The microplastic particles and thread-like fibres detected in these organisms were identified to be polystyrene by using DXR Raman microscope. Examination of the microplastic particle in Sternaspis scutata by epifluorescent microscopy showed fragmentation marks on the surface suggesting that the microplastic particle was degraded/weathered in nature. The study provides preliminary evidence of the presence of microplastics in benthic fauna from the coastal waters of India. However, further studies are required to understand the sources, distribution, fate and toxicity of the different types of microplastics in benthic invertebrates in order to identify any potential threats to higher trophic level organisms.     

Submarine experiments on benthic colonization of sediments in the western Baltic Sea. II. Meiofauna

From July, 1972 to February, 1973, meiofauna samples were taken from submerged platforms. Substrates were gravel, fine sand, and clayey mud. The individual samples consisted of 20 cm² 100 cm³. A diver collected the samples by hand. Some days after submersion of the platforms, colonization by meiofauna began. The submerged substrates were colonized almost exclusively by nematodes and harpacticoids; gastrotrichs were never present. In general, the harpacticoid fauna can be classified into two groups: the first, confined to the mesopsammon, did not colonize the platforms; the second, not limited to the interstitial habitat, did colonize. Two harpacticoid species, Ameira parvula and Danielssenia typica, were markedly dominant. The main migration route to the submerged platform was up the securing lines.Contribution no. 35 from the Sonderforschungsbereich 95, Kiel.     

Sea ice microbial production supports Ross Sea benthic communities: influence of a small but stable subsidy

Diversity in guilds of primary producers enhances temporal stability in provision of organic matter to consumers. In the Antarctic ecosystem, where temporal variability in phytoplankton production is high, sea ice contains a diatom and microbial community (SIMCO) that represents a pool of organic matter that is seasonally more consistent, although of relatively small magnitude. The fate of organic material produced by SIMCO in Antarctica is largely unknown but may represent an important link between sea ice dynamics and secondary production in nearshore food webs. We used whole tissue and compound-specific stable isotope analysis of consumers to test whether the sea ice microbial community is an important source of organic matter supporting nearshore communities in the Ross Sea. We found distinct gradients in delta13C and delta15N of SIMCO corresponding to differences in inorganic carbon and nitrogen acquisition among sites with different sea ice extent and persistence. Mass balance analysis of a suite of consumers demonstrated large fluxes of SIMCO into the nearshore food web, ranging from 5% to 100% of organic matter supplied to benthic species, and 0-10% of organic matter to upper water column or pelagic inhabitants. A delta13C analysis of nine fatty acids including two key biomarkers for diatoms, eicosapentaenoic acid (EPA, 20:5omega3), and docosahexaenoic acid (DHA, 22:6omega3), confirmed these patterns. We observed clear patterns in delta13C of fatty acids that are enriched in 13C for species that acquire a large fraction of their nutrition from SIMCO. These data demonstrate the key role of SIMCO in ecosystem functioning in Antarctica and strong linkages between sea ice extent and nearshore secondary productivity. While SIMCO provides a stabilizing subsidy of organic matter, changes to sea ice coverage associated with climate change would directly affect secondary production and stability of benthic food webs in Antarctica.     

Submarine experiments on benthic colonization of sediments in the western Baltic Sea. I. Technical layout

Submarine sedimentary substrates have been exposed in a new-style special arrangement for benthic colonization. The experiment has been running for 2 years and is planned to continue as a long-term test for several more years, with the purpose of studying independently both the effects of hydrographic and biotic factors as well as those of substrate type. This is accomplished by 3 floating platforms. Each carries 3 open containers filled with clayey mud, sand, and gravel (70 cm diameter, 25 cm deep). The platforms are anchored close together at 11, 15 and 19 m water depths. Their distances from the sea floor vary between 5.5 and 2.0 m. The sediments were obtained from sand pits on land. Substrate samples are continuously taken by divers. Hydrographic data are available by direct measurements from a ship and automatic sensors. The characteristic sources of error of the experiment seem to exert no decisive influence on the benthic production data.     

Daphne: a new multimetric benthic index for the quality assessment of marine coastal environment in the Northern Adriatic Sea

A new benthic index, named Daphne, is proposed for the Northern Adriatic coastal area, near the Po river delta. It is based on six characteristics of the community that do not require in-depth taxonomic expertise: number of mollusc species, % of bivalves, % of polychaetes, abundance of the opportunistic species Corbula gibba, % of amphipods and number of 'typical mollusc species' that are individuated by multivariate analysis. The application of the index in selected stations along a gradient of decreasing disturbance shows that it is simple to use in regular monitoring campaigns and that the results are consistent with environmental quality data in the special conditions of this area subjected to considerable river runoff. The index can be used in addition and as a complement to more widespread indices (such as M-AMBI); a comparison of the two indices performance is discussed.     

Comparative study of vanadium biokinetics in three species of echinoderms

Vanadium-48 (as vanadate) was used to study the uptake, tissue distribution, depuration and food-chain transfer of vanadium through 3 species of echinoderms: the seastar Marthasterias glacialis L., the sea urchin Paracentrotus lividus Lmk. and the holothurian Holothuria forskali D.Ch.; all were collected from the littoral zone near Monaco. Uptake by all species was relativelyslow; after 3 wk exposure, isotopic equilibrium had not been reached and whole-body concentration factors ranged from 5 and 7 in the holothurian and sea urchin, respectively, to 18 in the seastar. Sixty-three to 77% of the incorporated radiotracer was associated with the body wall or test, suggesting surface sorption as the principal mechanism governing uptake from water. Stable vanadium measurements confirmed the preponderance of this element in the external hard parts of the echinoderms; however, concentration factors based on stable vanadium levels were significantly higher than those measured experimentally. Subsequent vanadium depuration rates were also species-dependent, with biological half-times for loss ranging from approximately 50 d in the sea urchin and holothurian to 123 d in the seastar. Food-chain transfer experiments indicated that seastars can assimilate and retain a large fraction of the vanadium ingested with food whereas sea urchins appear to lack this capability. The relative importance of the water and food input pathway in achieving vanadium levels in echinoderms is discussed in light of results of ⁴⁸V distribution in experimental individuals and stable vanadium distribution in samples from the natural environment.     

Deposit-feeding amphipods (Monoporeia affinis) reduce the recruitment of copepod nauplii from benthic resting eggs in the northern Baltic Sea

We experimentally investigated the effect of different densities of the burrowing, deposit-feeding amphipod Monoporeia affinis on the recruitment of zooplankton from benthic resting eggs. Intact sediment cores with in situ density and species composition of zooplankton resting eggs and benthic fauna were collected in the northern Bothnian Sea, part of the Baltic Sea. We removed as many M. affinis as possible from the cores and then added different numbers of M. affinis to the cores to generate a range of densities. The cores were exposed to different densities of M. affinis for either 3 or 40 days, after which the hatched zooplankton was registered. One subset of the cores were initially incubated under low temperature (2–3 °C, to prevent hatching) for 37 days (the resting phase), to allow for effects of M. affinis on unhatched resting eggs. These cores were then incubated under higher temperature (13 °C) for 3 days (the hatching phase), to induce hatching and allow for effects on hatching or hatched specimens. In a second subset of cores with the same time and temperature schedule, the M. affinis density was experimentally reduced at the start of the hatching phase, to evaluate the effect of M. affinis during the hatching phase. To a third subset of cores, we immediately initiated the hatching phase, without an experimental resting phase, to evaluate the effects induced during the resting phase. The most common zooplankton species that hatched was Eurytemora affinis (Copepoda), followed by Bosmina longispina maritima (Cladocera). In all cores that were subjected to a resting phase, the numbers of hatched E. affinis were log-linearly negatively related to density of M. affinis. An increase of M. affinis density from 1,000 to 5,000 individuals m⁻², normal field densities, reduced the hatching by 60–70%. The negative impact was mainly exerted during the hatching phase, suggesting predation on, burial of or physical injury of hatching nauplii or eggs in a late development stage as likely mechanisms. Also, the number of B. longispina maritima that hatched was reduced by M. affinis during the hatching phase, but no clear relation to density of M. affinis could be identified. The results show that M. affinis can reduce recruitment to zooplankton from benthic resting eggs. Such impact by the benthos on resting stages of zooplankton is therefore a potentially significant link between the benthic and pelagic systems. Received: 10 August 2000 / Accepted: 13 November 2000     

Biomagnification of trace elements in a benthic food web: the case study of Deer Island (Northern Yellow Sea)

In this study, we investigated the concentrations of ten trace elements (Cu, Zn, Mn, Se, Ni, Cd, Cr, Pb, Hg, and As) and their trophodynamics in a benthic food chain of Deer Island, Northern Yellow Sea. The concentrations of Cu, Zn, Mn, Se, Ni, Cd, Cr, Pb, Hg, and As in the food chain ranged from 3.2 to 23.2, from 71 to 227, from 7.4 to 45.6, from 0.44 to 5.80, from 0.73 to 7.60, from 0.14 to 1.65, from 0.68 to 6.70, from 0.08 to 1.86, from 0.08 to 1.18, and from 0.24 to 3.92 mg kg^?1 dry weight, respectively. Among these trace elements, the linear regression between the log-transformed concentrations of Hg and Cd and δ¹⁵N values showed statistically significant increase (p<0.05) with the slopes of 0.134 and 0.144, indicating biomagnification of Hg and Cd occurred in the benthic food chain of Deer Island. While the linear regression for other eight trace elements (Cu, Zn, Mn, Se, Ni, Cr, Pb and As) were characterised by extensive scatter with non-significant correlation coefficients (R ²=0.002–0.235) and slopes (p=0.079–0.875), indicating there were not biomagnified or biodiluted of these trace elements.     

A new quantitative analysis of ovarian development in echinoderms: the maturity stage index

This study developed an objective quantitative method for detecting small-scale temporal or spatial differences in gametogenesis in echinoderms. The method was applied to conventional monthly samples of the planktotrophic brittle star, Ophiopholis aculeata, collected at a single site in Newfoundland (eastern Canada) at 10–15 m depth. The samples were analysed to determine gonad index, oocyte size and gonadal stage using histology. The maturity stage index (MSI) was developed to integrate a measure of brittle star size (disc diameter), oocyte size and oocyte density. The MSIs ranged from 0 to 800 and had significantly different means among the four gametogenic stages (early growth, growth, mature and spent). The MSI was more sensitive in revealing significant differences between consecutive stages than any of its individual constituents. The MSI was also applied to gametogenic data from the lecithotrophic holothuroid, Mesothuria lactea, again revealing significant differences between successive oogenic stages. This method is expected to be useful in field and experimental studies of gametogenesis in echinoderms (and possibly other taxa), where it is important to detect not just the timing of annual peaks in reproduction but small differences in reproductive status among individuals or populations (e.g. from different habitats or feeding regimes).     

The Role of the Organic Particulate Matter in the Distribution of Trace Metals in Sea Water

Studies on the distribution of heavy metals in water began and developed within the framework of research which has as its main purpose the evaluation of the anthropomorphic impact upon the environment. This outlook has resulted in the investigation being directed towards a definition of the concentrations of the chemical species being examined.     

Role of salps in the flux of organic matter to the bottom of the Ligurian Sea

Sediment-trap samples were collected during and after the occurrence of a salp (Salpa fusiformis) bloom in the Bay of Villefranche, Mediterranean Sea, in April/May 1985. Large amounts of organic aggregates and faecal pellets were collected during the bloom. The aggregates were rich in carbohydrates and mineral grains and had similar rates of sedimentation (900 to 2 100 m d^-1) to those of the faecal pellets (1 000 to 2 000 m d^-1). The results of mineralogical and organic chemical analyses indicate the potential effect of these mucus-rich aggregates on local biogeochemical fluxes.     

Ecophysiology of the benthic amphipod Monoporeia affinis in an open-sea area of the northern Baltic Sea: seasonal variations in oxygen consumption and ammonia excretion

Seasonal variations in the oxygen uptake rate ( ) and ammonia excretion rate ( ) of the benthic deposit-feeding amphipod Monoporeia affinis vere studied in an open-sea population of the northern Baltic Sea during three consecutive years (1991 to 1993). In the early summer an increase in the weightspecific by 22% (standard 1-mg individual) was registered; an even more striking change was noted in the , which showed an increase in the early summer of ca. six times the extremely low winter/spring valnes. The metabolic changes observed could not be attributed to temperature, which remained at steadystate throughout the year, nor could seasonal variations in the biochemical composition of the amphipods explain the results. Therefor, it is evident that quality-food abundance following the sedimentation of the spring phytoplankton bloom induces the observed early-summer elevations in and . In turn, the marked decrease in the towards autumn reflects the gradual depletion of quality-food in the benthic environment. Atomic O: N ratios indicated that at the sampling location, M. affinis uses lipid almost exclusively for metabolic energy throughout the year, except in early summer when the use of lipid and protein was observed to be almost equal. Results also indicated a time-lag between sedimentation of the phytoplankton bloom and metabolic response in the amphipod population.     

Metabolism of two dominant epibenthic echinoderms measured at bathyal depths in the Santa Catalina Basin

Metabolism of two abundant echinoderm species constituting 99.6% of the epibenthic megafauna in the Santa Catalina Basin, off southern California, USA was measured at 1 300 m during the 1979 “Bathyal Expedition”. Specimens of the ophiuroid Ophiophthalmus normani and the holothurian Scotoplanes globosa, collected by the submersible “Alvin”, were individually placed in respirometers, and measured in situ for O₂ consumption and ammonium excretion rates. For O. normani, weight-specific O₂ consumption rates decreased with increasing weight and were of comparable magnitude to rates of deep-sea and shallow-water ophiuroids; excretion rates were highly variable. Population O₂ consumption and excretion rates for O. normani (estimated from size-frequency distribution, abundance, and rate regression equations) were 1 129.28 μl O₂ m^-2 h^-1 and 27.30 nmol NH ₄ ⁺ m^-2 h^-1. Weight-specific O₂ consumption and ammonium excretion rates of S. globosa decreased with increasing weight and were of comparable magnitude to rases of shallow-water holothurians. Population O₂ constimption and excretion rates of S. globosa were 1.38 μl O₂ m^-2 h^-1 and 4.86 nmol NH ₄ ⁺ m^-2 h^-1. Combined population O₂ consumption rates for O. normani and S. globosa are of comparable magnitude to that of the sediment community and plankton in the benthic boundary layer (sediment and overlying 50 m water column) of the Santa Catalina Basin.     

Survey of the occurrence and morphology of sub-cuticular bacteria in shelf echinoderms from the north-east Atlantic Ocean

Echinoderms from the shelf seas around the British Isles were examined by epifluorescence and transmission electron microscopy for the presence of sub-cuticular bacteria (SCB). Information was obtained on SCB distribution in 63 of the 88 species known from this area, and 40 of these contained SCB. The SCB were present in all five classes. Only 39% of the holothurian species had SCB. In each of the other four classes, 60% of the species were associated with SCB. No correlation was noted between host ecology and SCB distribution or morphology. SCB distribution appeared to be related to host phylogeny. Congeneric echinoderms almost always had or lacked SCB, and this was usually also true for co-familial species. SCB showed limited morphological diversity, with all of them fitting into a classification of three general types. There was no morphological evidence suggesting that they are chemoautotrophs or methylotrophs. Some species had two morphological types of symbiont. SCB load was quantified for four species, three of which had symbiont densities >10⁹ SCB g^-1 ash-free dry wt. SCB are probably heterotrophic and may be co-evolving with their hosts.     

Settlement, recruitment and potential predators and competitors of juvenile echinoderms in the rocky subtidal zone

Recruitment patterns of marine invertebrates are affected both by settlement and early post-settlement events. This study examined the settlement and recruitment patterns of echinoderms at three sites in the rocky subtidal zone of Bocabec Cove, Bay of Fundy, Canada using artificial turf collectors and quadrats on the natural substrate. Potential predators were quantified at two of the sites along transects and in 1-m² quadrats. Both potential predators and competitors were quantified in 0.0625-m² quadrats. Settlement varied across sites (1.5–3 km apart) and two years of sampling (2004, 2005). The site of most potential settlement differed for the three groups of echinoderms: sea urchins (Strongylocentrotus droebachiensis), sea stars (Asterias spp.) and sea cucumber (Psolus fabricii). Settlement densities on the artificial turf collectors tended to be greater than the densities of settlers on the natural substrate. On the natural substrate, the only significant difference between densities of juveniles over time was that newly settled sea stars were found in July and were not found the following October. Large lobsters and carnivorous worms were potential predators with densities that varied between sites. Potential competitors that differed in abundance between sites were herbivorous gastropods and conspecifics for sea urchins; and carnivorous worms for sea stars. This study suggests that patterns of recruitment are either set up by patterns of settlement or by events during the first few weeks/months on the benthic substrate for these echinoderms.     

The Role of Suspended Matter in Assessing the Assimilative Capacity Case Study of Two Estuaries in the Adriatic Sea

Suspended particulate matter has been studied in two Adriatic river mouths to assess its role as a transport vehicle for waste disposal into the Adriatic sea.

The larger of the two, the Adige River (northwestern Adriatic coast, Italy), carries large quantities of solids and builds up a prodelta. the Krka River (eastern Adriatic coast, Croatia, Yugoslavia) is a typical karst river, and carries small quantities of suspended matter, since it drains carbonate terrains.

The resulting disposal of contaminants into the Adriatic sea is largely governed by the adsorption/desorption processes occurring in the estuarine mixing region. Surface adsorption properties, the specific surface area, and the nature and reactivity of the organic film coating determine the partitioning of pollutants between the dissolved and particulate state.

The observations reported point to the key role of particulates in transport of pollutants from land to sea. the concept of the assimilative capacity of the estuarine area requires detailed scientific knowledge on the geochemical behaviour of particulates.

In the Adige River mouth, lead, chromium, zinc, and nickel are accumulated in the prodelta sediments, and thus the loading of the sea with these metals is diminished, whereas in the Krka River estuary, desorption and mobilization of some trace metals occurs.