• 検索結果がありません。

The contribution of excretion by demersal zooplankton, to nitrogen flux across the sediment/water interface in a coral reeflagoon : a preliminary account

N/A
N/A
Protected

Academic year: 2021

シェア "The contribution of excretion by demersal zooplankton, to nitrogen flux across the sediment/water interface in a coral reeflagoon : a preliminary account"

Copied!
8
0
0

読み込み中.... (全文を見る)

全文

(1)

uRull. .va.[ar. Sci. FisJ".., Kocai i Univ. No. 14, pp.15-22, 1994

Proceedings of the Concluding WorkshoP on Coral ReefStudies, Kochi, November 1993

The Contribution of Excretion by Demersal Zooplankton,

to Nitrogen FIux Across the SedimentlWater Interface in a

Coral Reef Lagoon: A Preliminary Account.

John W. BIsHopi and jack G. GREENwooD

School ofMarine Scienee & Department ofZoology, The University ofQueenstand, Queensland 4072, Australia

Abstract: Preliminary findings are presented on nitrogen levels in sediment pore-water and overlying seawater at two iocations on the Great Barrier Reef, and the contribution to nitrogen fiux via amrnonia excretion from de-mersal zooplankters (ostracods, copepods, mysids, cumaceans, amphipods, isopods and decapods). Full details wi11 be presented and discussed elsewhere once all data are analysed. Ammonia excretion rates increased pro-portionally with dry body weight of the zooplankters (2-107ng NH4-N ind'i h'i). ArTimonia accounted for 609o of DIN in the water column. DIN was 23-45 times more concentrated in pore water than in overlying water, pro-moting eenuxes. Prelirninary estimates of ammonium flux across the sediment!water interface through demersal zooplankton excretion, using the present rate-data and published population density estimates, suggest a mean rate of 46 ,uM NH4 m2 h'i. This represents approximateiy 19o and 249o of the ammonia stock in the lower water column and upper substrate respectively. Values exceed those detemimed for meiofauna, and are approximately 30e/o of those estimated for heterotrophs in the water column.

Key words: Demersal plankton, Nitrogen fiux, Great Barrier Reef

Introduetion

Coral reef lagoons can be nutrient limited (Kinsey and Domm, 1974; Cook et al., 1992),

greatly influencing benthic communities which themselves may be central to nutrient recycling (Andrews and Muller, 1983). Pelagic zooplankters release little of the nitrogen required by phytoplankters, most in the inshore waters of the Great Barrier Reef probably coming from sediments (Ikeda et al., 1982a). Kowever, Alongi (1989a) reported only a moderate nitrogen flux between benthic and pelagic regimes, fluxes from coral reef sediments being iow compared with those from temperate latitude sediments (Alongi, 1989b).

The roles of organisms that move across the interface has not previously been examined. Although benthic communities regenerate nitrogen and transport pore-water across the inter-face (Gray, l985; Colin et al., 1986; Kristensen, 1988), they also utilize dissolved nitrogen and consume phytoplankton (Alongi, 1989b; Cloern, 1982), resulting in a decreased net flux to the water columm.

By contrast, many zooplankters in coral reef waters are demersal (Sale et al., 1976), living in, on or near sediments but having a diel pattern of migration between the sediments and

wa-ter column (McWi-am et al., 1981; Alidredge and King, 1985; Jacoby and Greenwood, 1988;

] Perinanent address: Department of Biology, University of Richmond, VA. 23173, USA.

(2)

16

J. W. BISHOP AND J. G. GREENWOOD

Madhupratrap et aL, 1991). Despite their implied importance in the nutrition of corals (Porter and Porter, 1977; Jakubczak, 1989), and recycling of nitrogen (Carleton and Hamner, 1989), there have been no studies which quantify the latter.

This study measures rates of ammonium excretion by common demersal zooplankters, and

compares fluxes of ammonium from these organisms with fluxed rates reported previously in coral reef lagoons in the Great Barrier Reef. A more detailed account of the study and its methods is to be published elsewhere (Bishop and Greenwood, in press).

Materials and Methods

Nitrogen excretion by zooplankters was measured on Heron Reef in August and November 1991 and One Tree Reef in November 1991. Nitrogen concentrations in the water column and

sediments of both reefs were measured in November 1991. Sampling sites were in the Shallow and Blue Lagoons of Heron Reef, and the eastern side of the First Lagoon of One Tree Reef. Nitrogen excretion

Zooplankters were collected at night near lagoon sediments at depths of 14 m by rneans of a battery-operated pump (Dixon and Robertson, 1986), and an epibenthic sledge both at night and by day. The pump had a pumping capacity of 40-45 I min-i. The collecting chamber of the pump (9.5 cm i.d. x 16.5 cm 1) housed a removable polycarbonate plankton bucket fitted along the sides with plankton netting (O.2, O.5 or 1.0 mm mesh). During sampling, the pump inlet was lowered to the desired level for 10-15 min of pumping. The collecting chamber contents were carefully transferred to a partially filled container for return to the laboratory.

The sledge net (200 #m mesh, mouth O.3 x O.5 m) was towed 3 cm above the sediments

for 5-10 min. Captured organisms were transferred to a lightshielding container and returned to the laboratory.

Nitrogen excretion experiments began 1-4.5 h, after collections. Acid washed glassware was used throughout. Larger zooplankters known to be captured in demersal trap-nets Uacoby and

Greenwood 1988) were selected for experimentation. Actively swirnming specimens of each

taxon were pipetted into containers and rinsed three times in sea water previously filtered through combusted GFIF pads or Whatman # 1 qualitative filter paper. 1-16 individual zoo-plankters were then transferred into 50 ml glass vials with filtered sea water brought to a volume of 20 ml. The optimal number of individuals of each taxon necessary to release

detect-able amounts of ammonium had been previously determined. Control vials contained no

zoo-plankters. All vials were incubated in the dark for 6-7 h at 22-230C on Heron Reef and 24-270C

on One Tree Reef. About 909o of the data were obtained from studies on Heron Reef.

Addi-tional vials (without animals) were used to determine ammonium levels in the experimenta1 wa-ter medium prior to incubation. Following incubation, a wawa-ter subsample from each vial was passed through a precombusted GFIF pad into a nutrient tube and frozen. Test animals were carefu11y rinsed on a filter paper with distilled water and the paper wrapped in precombusted aluminium foi and frozen.

Aiitrogen concentrations in the water column and sediments

Water samples were syringed from approximately 2 and 20 cm above the sediments, stored

temporarily in a laboratory freezer, then filtered (precombusted GFIF pads) into nutrient tubes and frozen.

Triplicate sediment samples were taken at each site using a (2.9 cm i.d.) corer. The corer plus sediment was carefully stoppered and stored in a laboratory freezer for about 1 h.

(3)

Sub-DEMERSAL PLANKTON AND NITROGEN FLUX

17

samples from these samples were used for measurements of pore-water volume, particle size, and concentrations of nitrogen in the sediments and pore-water as follows.

The upper 2 cm of all sedirnent samples from each site were pooled, and portions frozen for later analyses of total nitrogen. Known volumes of the remainder were centrifuged at 2000 rpm

for 10 min. The resultant pore-water extract was measured for volume, fltered through a

GFIF pad into a nutrient tube, and frozen. The centrifugate and a solution of 1 N KCI (10 mYIO ml) were shaken for 5-30 min and centrifuged. The filtrate was filtered through a pre-viously combusted GFIF pad into a nutrient tube and frozen for later analyses of exchangeable nitrogen. Samples for particle size analyses were dried at 1050 for 24 h, shaken through a series of sieves (63-1180 ,am) and the fractions weighed.

All samples of water, sediments and macrozooplankters were transported in dry ice to the laboratory where they were stored (at -140C to -190C) prior to further analyses. Zooplankters

were freeze dried, and measured for body weight and total nitrogen (ANTEK system, Model 722 Pyroreactor and Model 707 Chemilminescent Nitrogen Detector). Samp}es of water were

analyzed for dissolved inorganic arrllnonia, nitrite and nitrate and total dissolved nitrogen (Skal-er 2140 segmented fiow analyz(Skal-er). Samples for estimation of total dissolved nitrogen w(Skal-ere photo-oxidized (Ultra-violet Photo-oxidation Unit, LaJolla Scientific) for 7 h prior to analyses. Water samples were analyzed for nitrogen using standard procedures (Ryle et al., 1981).

Summed values of nitrate, nitrite and ammonium in samples that were not photo-oxidized

yielded estimates of dissolved inorganic nitrogen (DIN). The sum of values of the same para-meters for photo-oxidized samples yielded estimates of total dissolved nitrogen (TDN). Differ-ences between values of TDN and DIN yielded estimates of dissolved organic nitrogen (DON). Concentrations of ammonium nitrate plus nitrite below detection ljmits were, for statistical

estimates, assumed to be at the detection limit (O.04 ,uM for ammonium, O.02 ,uM for nitrate

plus nitrite).

Differences between ammonium levels in the experimental and control vials were assumed to

be ammonium excreted by the zooplankters. The mean concentration of ammonium was less in

the control vials than in the initial vials, indicating a loss of ammonium in the contro! vials. On

average, it was 419o less in these where the sea water had passed through GF!F pads, and

329o less in sea water that had passed through Whatman # 1 filter paper, but these differences

were not statistically significant.

Only data from vials containing animais active at the end of the experiments were used, thus avoiding errors that often are introduced through the use of injured animals (Ikeda et al., 1982b; Omori and Ikeda, 1984). Concentrations of nitrogen and excretion rates are variously expressed in units of ,aM and ng NH4-N ind-i h-i to simplify comparisons with other studies.

Results

The following crustacean taxa were utilised in experiments: Ostracoda:

Copepoda

Calanoida: Cyclopoida: MonstriNoida: Mysidacea: unident myodocopan sp. Eucalanus subcrassus PseudodiaPtomus colefaxi Temora turbinata Oithona sp. Thaumaleus longisPinus Doxomysis littoralis D. sPinata

(4)

18

J. W. BISHOP AND J, G. GREENWOOD

HaPlostylus Paci ica Sin'ella quadrisPinosa

S. Iingvura

Sin'ella sp.

Cumacea: GlyPhocuma sp.

Schi2otrema sp.

Amphipoda: unident. dexaminid

Isopoda: unident. flabelliferan

Decapoda: thalassmid larvae.

Mean body dry weights and nitrogen contents were 126-2040 ,ug ind-i and 4-119o, respec-tively. Mean ammonium excretion rates ranged from 2 ng NH4-N ind-i h-i for isopods to 107 ng NH4-N ind-i h-i for decapods.

Excretion rates (ER) increased with dry body weight (BVV) according to the relationship

logioER = -1.01 + O.92 logioBW (r2= O.53, p < O.05) where ER is in (ng NH4-N indri h"i)

and BW is in ( yg ind-i). The values of the intercept and slope coefficient for copepods alone were -O.64 and O.82, respectively.

Table 1. Concentrations of nitrogen in the water column and substrates, and pore-water contents of substrates. Samples were taken from the water column at 2 cm and 20 cm above the strates and the upper 2-4 cm of the substrates in lagoons. Mean Å} S.D. and replicates.

Parameter Value

Nitrogen in water column ( ng N-l'i)

2 cm above substrate Dissolved arnmonia Dissolved inorganic Total dissolved 20 cm above substrate Dissolved ammonia Dissolved inorganic Total dissolved Nitrogen in substrate

Total nitrogen (9o dry weight)

Pore-water nitrogen ( ,ug N-ml pore-water-i) Dissolved ammonia

Dissolved inorganic Total dissolved

Pore-water nitrogen ( xig N-mi wet substraterr i)

Dissolved ammonia Dissolved inorganic Total dissolved

Exchangeable ammonia

Pore-water content (9o wet volume of substrate)

18.64 Å} 12.71 (47) 29.83 Å} 13.65 (47) 149.04 Å} 58.57 (47) 20.56 Å} 17.99 (22) 33.07 Å} 15.77 (22) 163.66 Å}104.30 (22) O.05 Å} O.83 Å} O.92 Å} 7.89 Å} O.25 Å} O. 28 Å} 2.39 Å} O.72 Å} 31.00 Å} O.Ol (20) O.95 (34) O.94 (34) 8.42 (34) 0.26 (32) O.26 (32) 2.48 (32) O.60 (30) 6.99 (36)

(5)

DEMERSAL PLANKTON AND NITROGEN FLTuTX

19

Differences between concentrations of each form of nitrogen on Heron and One Tree Reefs were not statistically significant so values from the two reefs were combined (Table 1). Aver-age concentrations of ammonia nitrogen in the water column were 18.64-20.56 ,ug NH4-N-I-].

Ammonia comprised about 609o of the DIN and DIN comprised about 20% of the TDN.

Sand comprised at least 929o by weight of the substrate, and silt and clay comprised the re-mainder. The average nitrogen content of the substrate was O.059o dry weight.

Mean concentrations of DIN were many times greater (23-45) in pore-water than in over-1ying water. The average concentrations were O.83 ptg NH4-N-ml pore water"i and O.25 /ig NH4-N-ml wet substrateMi Ammonia comprised about 909o of the DIN, and DIN comprised

ab-out 129o of the TDN.

The average concentration of exchangeable (associated with particles) ammonia was O.72 ,ug NH4-N-ml wet substrateri, which was about three times greater than concentrations in pore-water. Concentrations of exchangeable and pore-water ammonia were significantly correlated

(e-e.7o, p<o.os).

Conclusions and Discussion

Excretion rates, and functional relationships between excretion rates and body dry weights of demersal zooplankton were comparable to those Ikeda et al. (1982a,b) found for pelagic plankton artd Gray (1985) found for meiofauna in the GBR. Nitrogen contents of demersal plankton in Heron and One Tree Reefs (4-119o) were similar to those found for demersal zoo-plankton in Caribbean corai reefs (39o, Jakubczak 1989) and subtropical pelagic habitats (7-129o, Verity 1985). Daily turnover rates of body nitrogen in the demersal zooplankton (1-12%) were slrnilar to those of subtropical pelagic zooplankton (7-129o, Verity 1985), but lower than those of tropical pelagic zooplankton (20-5e9o, Gerber and Gerber 1979).

Concentrations of DIN and percentages of ammonia that comprised DIN in the water column were less in the present study than in previo'us studies of One Tree Reef (Hatcher and Hatch-er 1981; and HatchHatch-er and Frith 1985), but in the mid-range of DIN found at selected othHatch-er reefs (D'Elia and Wiebe 1990). Concentrations of DIN and percentages of arnmonia that com-prised DIN were 30-33 ug N-1-i and 639o in the present study ancl 62 ,ag N-1-i and 839o in

Hatcher and Frith (1985). Differences between sampling sites and seasons seem unlikely

reasons for these disparities, but differences in sample treatment might. Samples were unfil-tered in the previous studies and filunfil-tered in the present study. Exchangeable nitrogen associ-ated with particulates could have been included in previous estimates.

Ammonium concentrations in pore-water were many times greater than in the water column

(827 ,ag NH4-N-i compared with l9 ,ag ]vrI4-N-1-i). The high concentrations in pore-water indi-cate that the substrate could be a major source of nitrogen to overlying water. Mean concen-trations of pore-water nitrate and nitrite were within the midrange of previously reported

values. Exchangeable ammonia concentrations were neariy three times greater than pore-water ammonia concentrations. This ratio exceeded those reported by Garber (1984), and was within the range reported by Blackburn and Henriksen (1983). The strong gradient in nitrogen across

the sedimenVwater interface (104 ,uM porewater NH4; 2 ,aM water column NH4) would

prom-ote etifluxes. Effiux rate is also inversely related to ion exchange capacity (Blackburn and Hen-riksen, 1983). The exchange capacity of 3 found in our study would similarly promote rapid effiuxes. A considerable amount of ammonia appears to be sequestered by substrate particles. Exchangeable nitrogen could stabilize fluxes at the substrate-water interface and, in turn, sta-bilize concentrations of nitrogen in the overlying water. Rowe and Smith (1977) suggested that feedback of nutrients from substrates might help stabilize ecosystems that are dominated by

(6)

20

J. W. BISHOP AND J. G. GREENWOOD

nutrient inputs that are subject more to climatic than to seasonal variations. The reefs of this study were within 100 km of the mainland and could be influenced by runoff from the mainland as well as from islands in the reefs, which are inhabited by large populations of guano

produc-ing birds.

Ammonium fiuxes mediated through demersal zooplankters were estirnated by combining

data on zooplankton abundances from previous studies (e.g. McWilliam et al.; Alidredge and King 1985; Jacoby and Greenwood 1988; Jakubezak 1989; and Madhupratrap et al. 1991), with excretion rates found in this study. Estimated flux through the zooplankton was 46 "M NH4-N-m-2-h'i.This value provides only a rough idea of the nitrogen regenerated by demersal zoo-plankton, for it is based on population densities and excretion rates which vary 60 and 10 fold respectively, does not account for patchy distribution of zooplankton, which could have con-siderable effects locally, and focuses on selected zooplankters.

Preliminary calculations based on the above flux and assumptions about vertical distribution of zooplankters indicate that demersal zooplankton releases about 19o of the 20 mg

NH4-N-m-2

ammonia stock in the lower 1 m of the water column, and 249e of the 2.5 mg

NH4-N-m-2

ammonia stock in the upper 1 cm of substrate.

Our estirnate of demersal zooplankton contribution to anmionia flux in the sediments exceeds those reported for meiofauna in coral reef lagoons in the Great Barrier Reef (Gray, 1985; Capone et al., 1992) and is about 309o of reported flux from microhetereotrophs in the water column, where it could fil1 99o of the phytoplankter requirement (Hatcher and Frith, 1985; Hop-kinson et al., l987). The extent to which the demersal macrozooplankters transforrn nitrogen within the water column or sediments (e.g., consume and excrete in sediments), or transport nitrogen between the water column and sediments (e.g., consume in one location and excrete in another) remains unresolved.

Acknowledgments

We thank the Heron Island Research Station, University of Queensland and the Australian Institute of Marine Science, Townsville for the provision of facilities in both the field and laboratory to make this study possible. Many people assisted with both field and laboratory analyses, and their help and expertise is gratefu11y acknowledged, especialiy those at AIMS for assistance with chemical analysis. Financial support was provided by the Universities of

Rich-mond and Queensland, and a collaborative research grant with Kochi University Usa Marine

Biological Institute.

References

ALiDREDGE, A.L. and J.M. KiNG, 1985. The distance demersal zooplankton migrate above the benthos: tions for predation. Mar. Biol., 84, 253-260.

ALoNGi, D.M., 1989a. Benthic processes across terrigenous-carbonate sedimentary facies on the central Great Barrier Reef continental shelf. Contin. ShelfRes., 9, 629J663.

ALoNGi, D.M., 1989b. The role of soft-bottom benthic communities iri tropical mangrove and coral reef tems. Rev. Aquatic Sci. 1, 243-280.

ANDREwS, J.C. and H. MuLLER, 1983. Space-tirne variability of nutrients in a lagoonal patch reeL Limnol. Oceanogr., 28, 215-227.

BisHop, J.W. and J.G. GREENwooD, in press. Nitrogen excretjon by some demersal macrozooplankters in Heron

and One Tree Reefs, Great Barrier Reef, Australia. Mar. Biol.

(7)

DEMERSAL PLANKTON AND NITROGEN FLUX

21

Limnol. Oceanogr. 28, 477-493.

CApoNE, D.G., S.E. DuNHAIyl, S.G. HoRRIGAN and L.E. DuGuARy, 1992. Mcrobial nitrogen transformations

consolidated coral reef sedments. Mar. Ecol. Prog. Ser., 89, 75-88.

CtxRLEToN, J.H. and W.M. HtwitNER, 1989. Resident mysids: communlty structure, abundance and small-scale tributions in a coral reef lagoon. Mar. Biol. 102, 461-472.

CLOERN, J.E., 1982. Does the benthos control phytoplankton biomass in South San Francisco Bay? Mar. EcoL

Prog. Ser., 9, 191-202.

CoLIN, P.L., T.H. SucHANEK and G. McMuR'rRy, 1986. Water pumping and particulate resuspension by

lianassids (Crustacea: Thalassinidae) at Enewetak and Bikmi Atolls, Marshall Islands. Bull. Mar. Sci., 38, 19-24.

CooK, C.B., G. MuLLER-PARKER and D.F. D'ELIA, 1992. Arnmonium enhancement of the dark carbon fixation

and nitrogen limitation in symbiotic zooxanthellae: effects of feeding and starvation of the sea anemone sia Pallida. Limnol. Oceanogr., 37, 131-139.

D'EuA, C.F. and W.J. WIEBF., 1990. Biogeochemical nutrient cycles in coral-reef ecosystems. ln, Coral reefs,

edited by Z. Dubinsky Eisevier Science Amsterdam, The Netherlands,

DixoN, P. and A.1. RoBERTsoN, 1986. A compact, self-contained zooplankton pump for use in shallow coastal

habitats: design and perfomiance compared to net samples. Mar. EcoL Prog. Ser., 32, 97-100.

GARBER, J.H., 1984. i5Ntracer study of the short-term fate of particulate organic nitrogen at the sur:face of al marine sediments. Mar. EcoL Prog. Ser., 16, 89-104.

GERBER, R.P. and M.B. GERBER, 1979. Ingestion of natural particulate organic matter and subsequent tion, respiration and growth by tropical lagoon zooplankton. Mar. Biol., 52, 33-43.

GRAy, J.S., 1985. Nitrogenous excretion by meiofauna from coral reef sediments: Mecor 5. Mar. Biol., 89, 31-35.

HA't'cHER, A.1. and C.A. FRITH, 1985 . The control of nitrate and ammonlum concentrations in a coral reef

goon. CoralReefs., 4, IOILIIO.

HATcHER, A.1. and B.G. HA'rcHER, 1981. Seasonal and spatial variation in dissolved inorganic nitrogen in One Tree Reef lagoon. Proc. 4th Int. SymP. CoralReefs, 1, 419-424.

HopKINsoN, C.S., B.F. SHERR and H.W. DucKLow, 1987. Microbial regeneration of ammonium in the water

umn of Davies Reef, Australia. Mar. Ecol. Prog. Ser., 41, 147-153

IKEDA, T., J.H. CARLEToN, A.W. MITcHELL and P. DIxoN, 1982a. Ammonia and phosphate excretion by

piankton from the inshore waters of the Great Barrier Reef. Il. Their in situ contributions to nutrient eration. Aust. 1. Mar. Freshw. Res., 33, 683-698.

IKEDA, T., E.H. FAy, S.A. HuTcHINsoN and G.M. BoTQ, 1982b. Ammonia and inorganic phosphate excretion by zooplankton from inshore waters of the Great Barrier Reef, Queensland. I. Relationship between excretion

rates and body size. Aust. 1. Mar. FreshwaterRes., 33, 55-70.

JAcoBy, C.A. and J.G. GREENwooD, 1988. Spatial, temporal and behavioural pattems in emergence of ton in the lagoon of Heron Reef, Great Barrier Reef, Australia. Mar. Biol. 97, 309-328.

JAKLBczAK, R.S., 1989. The nutrition and neurophysiology of reef corals. Ph.D. Theses. Univ. Georgia, Athens,

GA., pp. 49-74.

JoHNsToNE, R., K. Koop and A.W.D. LARKuM, 1988 1989. Fluxes of inorganic nitrogen between sedments and

water in a coral reef lagoon. Proc. Linn. Soc. Ai.S. PIZ., 110, 219-227.

KiNsEy, D.W. and A. DoMM, 1974. Effects of fertilization on a coral reef environrnent-ptmary production dies. Proc. 2nd Int. SymP. CoralReef, Great Barrier Reef committee, Brisbane, 1, 49-66:

KRisTENsEN, R., 1988. Benthic fauna and biogeochemical processes in marine sedments: microbial activities and fiuxes. In, A[itrogen aycling in coastal man'ne environments, edited by T.H. Blackburn & S. Sorensen, John Wjley and Sons Ltd., pp. 275-299.

MADHupRATAp, M., C.T. ACHuTHANKu'M'Y and S.R. SREKuMARAN NAIR, 1991. Zooplankton of the lagoons of the

(8)

22 J. W. BISHOP AND J, G. GREENWOOD

McWiLLiAM, P.S., P.F. SALE and D.T. ANDERsoN, 1981. Seasonal changes in resident zooplankton sampled by

emergence traps in One Tree lagoon, Great Barrier Reef. f. ExP. Mar. Biol. Ecol., 52, 185-203. OMoRi, M. and T. IKEDA, 1984. Methods in man'ne zooplanleton ecology. John Wiley & Sons, N.Y.

PoRTER, J.W. and K.G. PoRTER, 1977. Quantitative sampling of demersal plankton migrating fi:om difEerent coral reef substrates. Limnol. Oceanogr., 22, 553-556.

RicKER, W.E. 1973. Linear regressions in fishery research. 1. Ftsh. Res. Bd. Canada, 30, 409-434.

RowE, G.T. and K.L. SMiTH JR., 1977. Benthic-pelagic couplmg in the mid-Atlantic bight. In, Ecology of marine benthos, edited by B.C. Coull, Univ. South Carolina Press, Columbia, S.C., pp. 55-65.

RyLE, V.D., H.R. MuELLER and P. GENTiAN, 1982. Automated analysis of nutrients in tropical sea waters. AIMS Tech. Bull. Ocean., Ser. 3.

SALE, P.F., P.S. McWiLLiAM and D.T. ANDERsoN, 1976. Faunal relationships among the near-reef zooplankton at

three Iocations on Heren Reef, Great Barrier Reef, and seasonal changes in this fauna. Mar. BioL, 49,

133-145. .

VERiTy, P.G., 1985. Ammonia excretion rates of oceanic copepods and implications for estimates of primary duction in the Sargasso Sea. Biol. Ocean,, 3, 249-283,

Table 1. Concentrations of nitrogen in the water column and substrates, and pore-water contents of          substrates

参照

関連したドキュメント

Keywords: continuous time random walk, Brownian motion, collision time, skew Young tableaux, tandem queue.. AMS 2000 Subject Classification: Primary:

We present sufficient conditions for the existence of solutions to Neu- mann and periodic boundary-value problems for some class of quasilinear ordinary differential equations.. We

In Section 13, we discuss flagged Schur polynomials, vexillary and dominant permutations, and give a simple formula for the polynomials D w , for 312-avoiding permutations.. In

Analogs of this theorem were proved by Roitberg for nonregular elliptic boundary- value problems and for general elliptic systems of differential equations, the mod- ified scale of

Then it follows immediately from a suitable version of “Hensel’s Lemma” [cf., e.g., the argument of [4], Lemma 2.1] that S may be obtained, as the notation suggests, as the m A

Definition An embeddable tiled surface is a tiled surface which is actually achieved as the graph of singular leaves of some embedded orientable surface with closed braid

Correspondingly, the limiting sequence of metric spaces has a surpris- ingly simple description as a collection of random real trees (given below) in which certain pairs of

[Mag3] , Painlev´ e-type differential equations for the recurrence coefficients of semi- classical orthogonal polynomials, J. Zaslavsky , Asymptotic expansions of ratios of