The primary production of two of the most commonly distributed benthic algae in the Baltic proper was measured using different in situ methods (bottles, plastic bags, 14C and O2) during summer. Results on exudation and heterotrophic activity of these exudates have been worked out for Fucus. Low primary production and exudation values are found, while the total bacterial activity seems to be high compared to the net primary production

Guterstam, B.

Iturriaga, R.

Wallentinus, I.

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Copyright ©Es gilt deutsches Urheberrecht.  Die Schrift darf zum eigenen Gebrauch kostenfrei heruntergeladen, konsumiert, gespeichert oder ausgedruckt, aber nicht im Internet bereitgestellt oder an Außenstehende weitergegeben werden ohne die schriftliche Einwilligung des Urheberrechtsinhabers. Es ist nicht gestattet, Kopien oder gedruckte Fassungen der freien Onlineversion zu veräußern. German copyright law applies.  The work or content may be downloaded, consumed, stored or printed for your own use but it may not be distributed via the internet or passed on to external parties without the formal permission of the copyright holders. It is prohibited to take money for copies or printed versions of the free online version. 257 Kieler Meeresforschungen Sonderheft 4 Kiel 1978 In situ primary production of Fucus vesiculosus and Cladophora glomerata* B. Guterstam, 1. Wallentinus and R. lturriaga*Askö Laboratory, University of Stockholm, Stockholm, Sweden and *Institut für Meereskunde an der Universität Kiel, Kiel, Germany (FRG)Abstract The primary production of two of the most commonly distributed benthic algae in the Baltic proper was measured using different in situ methods (bottles, plastic bags, 14C and 02) during summer. Results on exudation and heterotrophic activity of these exudates have been worked out for Fucus. Low primary production and exudation values are found, while the total bacterial activity seems to be high compared to the net primary production. Zusammenfassung Primärproduktion von Fucus vesiculosus und Cladophora glomerata in situ Die Primärproduktion der beiden am weitesten verbreiteten benthischen Algen der eigentlichen Ostsee wurde unter Verwendung verschiedener in situ Methoden (Flaschen, Plastiksäcke, 14C und 02) während eines Sommers gemessen. Bei Fucus wurde auch die Exudation und die heterotrophe Aktivität der Exsudate gemessen. Dabei ergaben sich geringe Primärproduktions- und Exsudationswerte, während die Gesamtbakterienaktivität, verglichen mit der Nettoprimärproduktion hoch erscheint. lntroduction The metabolism of phytobenthic communities has been shown to be significant through the analysis of energy- and material flows in the Baltic ecosystem (JANS­SON, 1972; in press). Information on primary production, distribution of benthic plants and their sensitivity to changes in the environment has become increasingly necessary in recent years as human pollution in the Baltic has increased (NORIN and WAERN, 1973; PEKKARI, 1973; NOTINI, 1978; WALLENTINUS, 1976b). During joint investigations by Working Group 3 of the Baltic Marine Biologists in June 1975-1976 benthic algae production, as weil as the structure and function of a particular Fucus vesicu/osus community were studied. This paper gives some results of the primary production of two of the most commonly distributed algae in the Baltic. *) Baltic Marine Biologists Publication No. 4 258 B. Guterstam et al.: Primary production of macroalgae Material and Methods The experiments were carried out at the marine biological station of Kämpinge on the southcoast of Sweden (Fig. 1). The experimental site was located at the southern end of the Falsterbo channel, which is protected from storm by a con­crete wall. The salinity here is around 10°/oo, 24° Figure 1 The Baltic Sea and the location of the experimental site (E) Nr.98 --- - 64 26° 28° 30° B. Guterstam et al.: 259 In situ primary production was measured in bottles (1.2 1 at 4 and 24 h periods, WALLENTINUS, 1976 a) and in plastic bags (of sizes varying from about 50 to 100 1. for 1-2 days; Fig. 2, SCHRAMM and MARTENS, 1976; GUTERSTAM, 1977. In the former, parts of algae were incubated, while in the latter whole algae were enclosed. Figure 2 The experimental set-up for in situ studies of benthic algal metabolism. 1-2. Plastic bag (50 1, 50 cm diam.) with continuously registering Orelectrodes.3. Thermistor4. Underwater light sensor5. Solarimeter 6. The electrical supply to the sensors and the recording of data on land For the bottles the 14C method was used (5 [J, Ci/1 of NaH 14C03, no correction for dark fixation was made; WALLENTINUS, 1976 a) and in the plastic bags the net 02-output was measured by continuously recording Orelectrodes (SCHRAMM and MARTENS, 1976). In June 1976 both 14C- and Ormethods were used simultaneously in two 50 1 plastic bags. Two similar specimens of F. vesicu/osus (about 10 g dry wt.), cleaned of most of the epifauna, were incubated for a 7 h period (12-19 h, 13th June 1976). A concentration of about 40 11. Ci/1 of Na H 14CQ3 was used in the plastic bags in order to measure plant photoassimilation and release of extracellular compounds (FOGG, in: VOLLENWEIDER, 1974). 260 B. Guterstam et al.: Primary production of macroalgae The contribution from the phytoplankton to primary production in the plastic bags was measured separately in 50 ml water samples. In one of the plastic bags heterotrophic activity on the exudates produced by the algae was measured using 50 ml water samples taken after the incubation period. The water samples were mixed 1: 1 with natural bacterial populations and incubated in situ for 2 h (ITURRIAGA and HOPPE, 1977). In the other plastic bag the bacterial activity was considered to have been arrested by injection of a broad spectrum antibiotic (Gentamycin 40 mg/1). Analysis of the amount of exudates, the phytoplankton 14C-assimilation and the heterotrophic uptake of exudates was done by the liquid scintillation technique (ITURRIAGA and HOPPE, 1977). Analysis of carbon assimilated by the benthic algae was done by the liquid scintilla­tion technique after washing in sea water, freezing to - 18 °C, freeze-drying and dry combustion (WALLENTINUS, 1976a). The algae used for only the 02-method were dried at 60 °C until constant weight. Light was measured continuously above the water surface with a solarimeter (KIPP and ZONEN, 300-2500 nm). The photosynthetically active part of the spectrum (400-700 nm) was calculated as 45% of the measured insolation (v. BRÖCKEL, 1975). Results The net primary production of C. glomerata and F. vesicu/osus are given in Table 1. For comparison between the 1 4C- and the Ormethod both were considered to measure net primary production (a PQ of 1.2 was used for the conversion of Or values into carbon). C. glomerata showed a net primary production over 24 h that was similar in bottlesand in plastic bags, while by F. vesicu/osus the net primary production was higherin the bottles than in the plastic bags. This difference was also found when usingthe two methods (1 4C and 02) in the same plastic bag (Table 1). For comparisonthe results of an experiment with F. vesicu/osus in the northern Baltic proper aregiven in Table 1.A good correlation between fluctuations in light intensity during the day and the net primary production could be seen for both algae (Fig. 3). The production rate per g dry wt. and hour of C. g/omerata was about 4 tim es higher than that for F. vesicu/osus. Maximum net primary production was about 3 mg C g dry wt - 1 h- 1 in C. glomerata and 0.8 in F. vesicu/osus. The higher production per gram algae by C. glomerata can be explained by its filamentous structure which results in a relatively higher metabolism (ODUM et al., 1958). The thicker thallus of F. vesicu/osus leaves many of the cells photosynthetically inactive. This could be seen in the distribution of assimilated carbon whithin the algae (Fig. 4). Most of the assimilated carbon (74 %) was found in the tips. Using the plastic bag technique the exudation rate of Fucus could be measured and also the heterotrophic utilisation of the exudates by added natural bacterial population. At an in situ temperature of 17 °C in June the exudates (measured as 1 4C) and the phytoplankton primary production each made up 3% of the C assimilatedTable 1 The net primary production of C. glomerata and F. vesiculosus comparing 14 C-and Oz-methods together with some environ-mental parameters Net primary production as m g C g dry wt 1 exp. time 1 C.glomerataF.vesicu/osusExposure-lrradiance1) Locality time 02 14 c 1 4C/02 02 1 4c1 4C/02 kJ m-2 exp. time-1Kämpinge, 750604 ��2, 79 1,07 4,02 1,80 9541 southern (00-24) 2,78 2,60 Baltic 750604-05 24,45 7,67 7813 (11-11) (29,83)2) (9,39)2) 7,223) 760613 1,84 5,21 2,83 3659 (12-19) Askö 730817 northern (00-24) 6,56 9,89 1, 18 9349 Baltic 7,943) 1 ) PAR at surface2 ) Sum of 4 hour-experiments3 ) Recalculated for whole plants from experiments with apical parts only, with 1.3 times higherproduction. Used for comparisons of 14C-and 02-methods.Temp. Sal. o c0 /ooEnclosure 12 9 plastic bags 12 9 bottles 17 10 plastic bag 19 6 plastic bag (02), bottle (14 c). � G') c (D 3 � � .. � 3 Ol '< -0 0 0 :J s. 3 Ol 0 � (0 Ol 262 B. Guterstam et al.: Primary production of macroalgaeInsolation and primary production of Cladophora glomerata and Fucus vesiculosus QJ u 1500 § 500 u '­H "Ci � u Ol E QJ Ol c:, 0 +4 3 2 0 2 -3+1,o 0,o -1,o Figure 3 3-5 June 1975 Cladophora Fucus / I I / tips 14c uptake , bottles 1 L parts of algae 02 output, plastic bags 100 l, whole algaeThe daily fluctuations in light intensity (4-5th June 1975) and the rate of change in oxygen output (recalc. to carbon see text, plastic bags) and in carbon assimilation (14C bottles) for C. g/omerataand F. vesicu/osus B. Guterstam et al.: Primary production of macroalgae 263 Distribution of assimilated carbon in Fucus vesiculosus L. mgC/g d.wt. % of .Z:: C ass. Figure 4 7, 15 ± 1,10 74 ± 6 3,41 ± 0,54 25 ± 6 1,53 ± 0,62 1±D ( n = 2 , ± S. D.) Distribution of assimilated carbon in F. vesiculosus (mean of the two plants used) 264 B. Guterstam et al.: Primary production of macroalgae by Fucus when the heterotrophic activity in the water was 0.1 % (Table 2). The turn­over time of exudates was calculated to be 208 h. The same water samples showed a heterotrophic uptake of glucose (Vmax, ITURRIAGA, 1977) of 0.0206 (J.g C 1 1 h 1 with a turn-over time of 48 h. Table 2 The distribution of photoassimilated carbon measured as 14C (F. vesicu!osus in plastic bags, 13th June 1976, after 7 h incubation in situ at 1 m depth) Fucus (11,45 g dry wt) Fucus + antibiotics (9,67 g dry wt) mg C g dry wt- 1 % mg C g dry wt- 1 % Fucus 59,67 5,21 100 54,23 5,61 100 Exudation 1,75 0, 15 3 1,23 0, 13 2 Phytoplankton 1,76 3 1,40 3 Bacteria1) 0,06 0, 1 1) assimilation of exudates measured after 7 h incubation. This value is calculated from a bruttouptake rate of 0,48% h-1 Discussion and Conclusions The net primary production of C. g!omerata was similar to the values found by WALLENTINUS (1976a) in the northern Baltic (2.4-13.7 mg C g dry wt -1 h- 1). The large variation reflects the different ages and conditions in the population of this seasonally (summer) occurring algae. F. vesicu/osus also showed similar values to those found by GUTERSTAM (in prep.) using plastic bags and the Ormethod in the northern Baltic proper (average 0.72 mg C g dry wt- 1 h- 1 Feb.-Sept. at maximum daily insolation). Laboratory experiments with F. vesicu!osus from the western Baltic showed higher values (about 2 mg C g dry wt-1 h-1, recalc. from KING and SCHRAMM, 1976). The results on relative assimilation rate in different parts of the Fucus plants (tips: middle :base in ratio 5: 2: 1) were similar to those of WALLENTINUS (unpubl.) using 14C in plastic bags in the northern Baltic proper, although the total assimila­tion was slightly lower (0.67 mg C g dry wt.- 1 h- 1). She also found that if the pro­ductivity was calculated per unit of chlorophyll the differences in metabolic activity between the different parts were stil I more emphasized (14: 2: 1 ). Also if the different parts of the plants were separated before the experiments, about the same relations of carbon assimilation to weight (6: 2: 1) were found in glassbottle experiments in July in the northern Baltic proper, and with the assimilation of the whole plants (small specimens) about the same, too (ca. 3.5 times that of the basal parts, or 0.76 mg C g dry wt - 1 h-1, ca. 60% of the values for the tips only, calculated per weight unit). lf the middle parts were heavily covered with epiphytes, Elachista fucico!a, the productivity of those parts expressed per dry weight was almest doubled, even if the epiphytes did not comprise a major part of the weight (WALLEN­TINUS, unpubl.). The low exudation rate compared to those measured in laboratory experiments by SIEBURTH (1969) an-d KHAILOV and BURLAKOVA (1969), who measured an B. Guterstam et al.: Primary production of macroalgae 265 exudation rate of about 40% of the net primary production by F. vesicu/osus, is explained by the fact that they measured total dissolved organic carbon (DOC) released from the algae. In view of these results we could conclude that our values for exudation of newly assimilated carbon (14C method) underestimate the total exudation. On the other hand, MOEBUS and JOHNSON (1974) found no exudation (DOC) by F. vesiculosus under laboratory conditions. The heterotrophic activity measured in the surrounding water of Fucus is only a part of the total bacterial activity in a Fucus community. A higher total bacterial activity in our experiments where only Fucus was used, without the natural substrate was indicated by the difference in 02-output between the two plastic bags with and without antibiotics (0.36 and 0.26 mg C g dry wt - 1 h-1). For comparison the heterotrophic uptake of phytoplankton exudates in summer in the western Baltic was 8-17% per hour. These differences between the plastic bags reflect the import­ance of the bacteria even for the transfer of energy and recycling of nutrients in phytobenthic communities. The discrepancy between the two methods used for primary production measure­ments (especia!!y by Fucus), considering both (02 and 14C) measure net primary production (JOHNSTON and COOK, 1968), may be a result of a high 0-2-consump­tion by the heterotrophic organisms during the summer and even if the 14C-values here are not corrected for dark fixation, this cannot account for more than a very low part of the higher figures for the 14C-method. Other experiments have shown (WALLENTINUS, unpubl.) that even if the dark fixation by Fucus vesiculosus is higher than by the filamentous algae, it amounts only to about 2-6% of the light fixation du ring daytime; the highest figures for the basal parts and the lowest for the not separated tips. Higher percentage values ar.e, of c.ourse, found during dawn and dusk. References v. BRÖCKEL, K.: Der Energiefluß im pelagischen Ökosystem vor Boknis Eck(westl. Ostsee). SFB 95. Rep. 10, 1-96 Univ. Kiel (1975)FOGG, G. E.: Extracellular products of phytoplankton. In: IBP Handbook 12, pp. 97-98 Ed. by R. A. VOLLENWEIDER. Oxford, London, Edinburgh, Melbourne: Blackwell (1974) GUTERSTAM, B.: An in situ study of the primary production and the community metabolism of a Baltic Fucus vesicu/osus L. community. 11th European Symposium on Marine Biology, Galway, lreland, Oct. 1976, 311-319 (1977) ITURRIAGA, R.: Mikrobielle Aktivität des Aufwuchses von Sinkstoffen in der Kieler Bucht. Dissertation Univ. Kiel (1977) ITURRIAGA, R. and H.-G. HOPPE: Observations of heterotrophic activity on photo­assimilated organic matter. Mar. Biol. 40, 101-108 (1977) JANSSON, 8.-0.: Ecosystem approach to the Baltic problem. Bull. Ecol. Res. Comm. NFR 16, 1-82 (1972) JANSSON, 8.-0.: The 8altic - A systems analysis of a semi-enclosed sea. Joint Oceanographic Assembly 1976. General Symposia. Ed. by H. CHARNOCK and G.E.R. DEACON. Plenum Press (in press) JOHNSTON, C. S. and J. P. COOK: A preliminary assessment of the techniques for measuring primary production in macrophytic marine algae. Experientia 24, 1176-1177 (1968) 266 8. Guterstam et al.: Primary production of macroalgae KHAILOV, K. M. and Z. P. BURLAKOVA: Release of dissolved organic matter by marine seaweeds and distribution of their total organic production to inshore com­munities. Limnol. Oceanogr. 14, 521-527 (1969) KING, R. and W. SCHRAMM: Determination of photosynthetic rates for the marine algae Fucus vesicu/osus and Laminaria digitata. Mar. Biol. 37, 209-213 (1976) MOEBUS, K. and K. M. JOHNSSON: Exudation of dissolved organic carbon by brown algae. Mar. Biol. 26, 117-125 (1974) NORIN, L.-L. and M. WAERN: The zone of algal low standing crop near Stockholm. Nutrients and their influence on the algae in the Stockholm archipelago during 1970. No 5. Oikos Suppl. 15, 179-184 (1973) NOTINI, M.: Long-term effects of an oil spill on Fucus Macrofauna in a small Baltic bay. J. Fish. Res. Bd. Can. 35, 745-753 (1978) ODUM, E. P., E. J. KUENZLER and M. X. BLUNT: Uptake of P32 and primary pro­ductivity in marine benthic algae. Limnol. Oceanogr. 3, 340-345 (1958) PEKKARI, S.: Effect of sewage water on benthic vegetation. Nutrients and their influence on the algae in the Stockholm archipelago during 1970. No 6. Oikos Suppl. 15, 185-188 (1973) SCHRAMM, W. and V. MARTENS: Ein Mess-System für in situ Untersuchungen zum Stoff- und Energieumsatz in Benthosgemeinschaften. Kieler Meeresforsch. Son­derheft 3, 1-6 (1976) SIEBURTH, J. McN.: Studies on algal substances in the sea III. The production of extracellular organic matter by littoral marine algae. J. exp. mar. Biol. Ecol. 3, 290-309 { 1969) WALLENTINUS, 1.: Productivity studies on Cladophora g/omerata (L. ) Kützing in the northern Baltic proper, Proc. 10th European Symp. Mar. Biol. Ostend, Belgium, Sept. 1975, 2, 631-651 {1976a ) WALLENTINUS, 1.: Environmental influences on benthic macrovegetation in the Trosa-Askö area, northern Baltic proper 1. Hydrographical and chemical para­meters, and the macrophytic communities. Contrib. Askö Lab. Univ. Stockholm 15, 1-138 (1976b )

In situ primary production of Fucus vesiculosus and Cladophora glomerata

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In situ primary production of Fucus vesiculosus and Cladophora glomerata

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