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Enrichment of inorganic nutrients in the Western Saronikos Gulf
Marine Pollution Bulletin the Department of Zoology, Andhra University, for excellent laboratory facilities.
American Public Health Association (1971). Standard Methods for the Examination o f Water and Wastewater, 13th Edition. American Public Health Association, Washington, D.C. Anger, K. (1975). On the influence of sewage pollution on inshore benthic communities in the South of Kiel Bay. Part 2. Quantitative studies on community structure. Helgoltlnder wiss. Meeresunters., 27, 408-438. Bagge, P. (1969). Effects of pollution on estuarine ecosystems-l. Effects of effluents from wood-processing industries on the hydrography, bottom and fauna of Saltkallefjord (W. Sweden). Merentutkimuslait. Julk./Havsforsk Inst. Skr., Helsingf., 228, 3-118. Ganapati, P. N. (1969). Biology of pollution in Visakhapatnam Harbour. Mar. Poilu& Bull., No. 16: 1-3. Ganapati, P. N. & Raman, A. V. (1973). Pollution in Visakhapatnam Harbour. Curr. Sci., 42, 490-492. Ganapati, P. N. & Raman, A. V. (1979). Organic pollution and Skeletonema blooms in Visakhapatnam Harbour. Indian J. mar. Sci., 8, 184-187. Leppakoski, E. (1975). Assessment of degree of pollution on the basis of macroznohenthos in marine and brackish-water environments.
Acta. Acad. .~bo. Ser. B. Math. Phys. Mat. Naturvetensk. Tek., 35, 1-90.
Mare, M. F. (1942). A study of marine benthic community with special reference to the microorganisms. J. mar. biol. Ass. U.K., 25, 517-554. Parrish, L. P. & Mackenthun, K. M. (1968). U.S. Department of the Interior. San Diego Bay: A n evaluation o f the benthic environment. Federal Water Pollution Control Administration, Technical Advisory and Investigations Branch Report (5555, Ridge Ave., Cincinnati, Ohio), 31 pp. Pearson, T. H. & Rosenberg, R. (1978). Macrobenthic succession in relation to organic enrichment and pollution of the marine environment. Oceanogr. mar. Biol. A. Rev., 16, 229-31 I. Reish, D. J. (1959). An ecological study of pollution in Los AngelesLong Beach harbors, California. Occ. Pap. Allan Hancock Fdn. 22, 1-119. Remane, A. (1971). Ecology of brackish water. In Biology o f Brackish water (A. Remane and C. Schlieper, eds.), pp. 1-180. John Wiley, New York. Rosenberg, R. (1975). Stressed tropical faunal communities off Miami, Florida. Ophelia, 14, 93-112. Sanders, H. L. 0968). Marine benthic diversity: A comparative study. Am. Nat., 102, 243-282. Wade, B. A. (1976). The pollution ecology of Kingston Harbour, Jamaica: I I. Benthic ecology. Scientific Report of the U. W.I. -0. D. M. Kingston Harbour Research Project, 1972-1975. 104 pp.
MarinePollutionBulletin,Vol.14,No.2, pp. 52-57,1983 PrintedinGreatBritain
0025-326X/83/020052--06$03.00/0 1983PergamonPressLtd.
Enrichment of Inorganic Nutrients in the Western Saronikos Gulf N. FRILIGOS
Institute of Oceanographic and Fisheries Research, Athens, Greece Studies of nutrient enrichment in the Western Saronikos Gulf for the period 1973-1976 are presented here. Also, a comparison of nutrient enrichment is made between the Western and Inner Gulfs and Elefsis Bay. The Western Gulf and Inner Gulf appear to hold phosphate equally. However, the tendency for silicate to be depleted in the Inner Gulf is clear, while the Western Gulf tends to accumulate silicate more than phosphate. Nitrate tends to be accumulated even more than silicate in the Western Gulf. Elefsis Bay accumulated more nutrients than the other gulfs, especially inorganic nitrogen. This was mainly due to the different sources of nutrients as well as the morphology of each area and the circulation of the waters. The water masses of the Western Gulf were renewed in Spring 1974, as can be seen from the silicate values which fell by 1/3. Nutrient ratios in the Western Gulf were close to normal.
Saronikos Gulf, the marine gateway to the metropolitan Athens area of Greece, invites the attention of marine scientists because eutrophication and other alterations are occurring in its naturally oligotrophic waters as a consequence of urban waste disposal. Domestic sewage contains a great amount of nutrients, especially chemical compounds with nitrogen and phosphorus, and consequently produces an increase in eutrophication. This manmade eutrophication can be measured in its occurrence and geographic extent by measurements of nutrients. This paper presents the chemical results found from 1973 to 1976 in the Western Saronikos Gulf. More specifically, 52
this paper examines the nutrient enrichment in the Western Saronikos Gulf from the baseline values outside the Saronikos Gulf to those values found in areas influenced by the sewage outfall and industrial effluents at the apex of the Gulf. Prior to these studies, the seasonal variation of the spatial distribution and the relationship between nutrients in the Western Saronikos Gulf had only been studied over relatively short periods, or at a limited number of stations (Dugdale & MacIsaac, 1975; Friligos, 1976).
Material and Methods The sampling area was the western part of the Saronikos Gulf, Aegean Sea, whose topography has been described elsewhere (Friligos, 1982). Stations FA, HA, JA, N, D, CA, BA (Fig. 1) were chosen in the Western Saronikos Gulf following the results and terminology used in the water masses report (Coachman & Hopkins, 1975). Samples of water were collected from 1, 10, 20, 50, 75,100, 125, 150, 200, 250, 300, 350 and 400 m using Nansen reversing water samplers. The sampling was done at seasonal intervals during 1973-1976. It should be noticed that investigations on nutrients were carried out in the Western and Inner Gulfs and Elefsis Bay during the same cruises. Measurements of inorganic nutrients were made by methods described by Friligos (1979). The same methodology was followed for calculating the level of enrichment by inorganic nutrients as in the case
Volume 14/Number 2/February 1983
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of the Elefsis Bay (Friligos, 1981) and the Inner Gulf (Friligos, 1982).
Results and Discussion The western part of Saronikos Gulf is the deeper. From west of Salamis to the Korinthos-Loutraki land bridge the basin is 130 m, which connects to the south with a deep (~400m) depression in Epidavros basin. The western Saronikos Gulf receives only biologically filtered or chemically altered pollutants from the sewage outfall. Some of the characteristics of the sewage have been described elsewhere (Friligos, 1982). Hopkins (1974) reported that the Western Basin, with its stagnant or partly stagnant conditions, is especially sensitive to pollution due to slow water exchange. Such an area presents a neutrally stable condition in winter which causes the formation of a light surface water layer, which isolates the heavier deep water from contact with the atmosphere. Two shallow sills, one in the north between Salamis and Aegina, with a sill depth of about 100 m, and the other to the south between Aegina and the Methanon peninsula, with a sill depth of 80 m, restrict the horizontal water exchange. Dugdale & MacIsaac (1975) and Friligos (1976) reported that this basin acts as a nutrient trap. Nutrients are removed from the surface water through uptake by microorganisms. When these organisms die, the whole or a part of tfiem sinks through the halocline into deep water. Through bacterial oxidation processes the nutrients of these organisms revert to the inorganic form and are dissolved. Figure 2 shows a comparison between vertical distribution of oxygen, nitrate and silicate in Epidavros (st. JA) and in the Aegean water just out from the Saronikos. The nutrient accumulation and oxygen depletion are obvious. The fact that such vertical gradients exist
throughout the neutrally stable conditions of winter suggests that the bottom waters are convectively not flushed annually. For most of the year the deep waters gain oxygen and nutrients through the weak process of vertical diffusion. With an increased organic load from the Athens outfall, it is only a matter of time before Epidavros Basin becomes anoxic, resulting in very serious consequences to the surrounding fisheries. The total nutrient of the Western Gulf was determined for sixteen cruises SSP 2-SSP 21 (January 1973-September 1976). From Fig. 1 it can be seen that in the Western Gulf
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Fig. 2 Oxygen (in ml I - I), nitrate (in ~g-at I - ]) and silicate (in ~g-at 1- 1) comparison between Epidavros Basin and the Aegean just south of Saronikos.
53
Marine Pollution Bulletin
most sample line in the Eastern Gulf. All available SSP data were used in the calculation and these values were quoted by Friligos (1981) in Table 3. Mean nutrient concentrations for cruises SSP-2 and 7-21 are shown in Tables 2a and 2b for the Western Gulf, subdivided by depth ranges. The concentration of silicate and nitrate are often considerably above the background levels of Table 3 (Friligos, 1981), where accumulation of nutrient in the deep water is apparent. Mean concentrations for the various depths and cruises as shown in Tables 3 (Friligos, 1981) and 2a, 2b were multiplied by the appropriate volumes given in Table 1 to obtain an estimate of total nutrient held in dissolved form in the Western Gulf. The results are presented in Table 3 along with background values. The latter were computed from the mean concentrations for the Outer Gulf water (Table 3; Friligos, 1981) and the appropriate volumes (Table 1). All five nutrients are present in all areas at levels well above background. From these data it appears that total nutrients do not vary widely from cruise to cruise, although after SSP-8 the amounts of silicate and phosphate declined, while total inorganic nitrogen increased. Between cruises 8 and 11 (December 1973-June 1974), there was massive transport of deep Western Gulf water (Coachman & Hopkins, 1975), probably the cause of such changes.
TABLE 1 Volumes of Western Gulf. Total surface = 1 i 17 x 106 m 2. Depth interval (m)
V( x l06 m 3)
0-100 100-200 200-300 300--400 400-428 Total
85 287 39 859 13 878 4518 294 143 836
there is a considerable area with depths below 100 m, providing the possibility for trapping of nutrients. The Epidavros depression has a maximum depth of more than 400 m. The approximate volumes of the respective basin, divided into appropriate depth ranges, are given in Table 1. Current levels of circulatory nutrients were estimated by computing mean values for the depth intervals indicated in Table 2a and 2b, station by station (FA, HA, JA, N, D, CA, BA), and combining these to give mean values. The mean values were multiplied by the appropriate volumes to give quantitative estimates of total nutrients contained in the basin (Table 3). The mean values for the Outer Gulf water, the source water for the region, were obtained from 0-100m samples at stations LA, MA and NA, located along the southern-
TABLE 2A Mean nutrient concentrations in the Western Gulf; water column averages in ~g-at I - I Cruise
Date
PO4-3p SiO~-4-Si NO~- - N SSP- 2 SSP- 7 SSP- 8 SSP- 9 SSP-10 SSP-I l SSP-12 SSP-13 SSP-14 SSP-15 SSP-16 SSP-17 SSP-18 SSP-19 SSP-20 SSP-21
Jan. 73 Oct. 73 Dec. 73 Feb. 74 Apr. 74 Jun. 74 Nov. 74 Dec. 74 Feb. 75 Apr. 75 Jun. 75 Sept. 75 Dec. 75 Mar. 76 Jun. 76 Sept. 76
Depths 100-200 m
Depths 0-100 m
0.20 0.14 0.21 0.10 0.19 0.22 0.12 0.20 0.84 . 0.19 0.11 0.23 0.20 0.12 0.11
3.72 2.31 1.84 2.50 2.47 1.42 2.01 1.46 2.39 .
0.17 0.14 0.20 0.17 0.19 0.21 0.17 0.13 0.42 .
1.13 1.38 1.38 3.72 1.94 1.71
. 0.09 0.29 0.11 0.61 0.18 0.07
NO~- - N 0.40 1.48 1.09 1.59 3.48 2.44 2.18 0.77 1.24 . 0.83 0.70 0.90 2.44 1.25 1.10
NH~- - N P O ~ - 3 - P SiO~-4-Si NO~- - N 0.57 0.83 0.54 0.76 0.63 0.83 1.59 2.25 2.48 . 0.40 1.25 0.75 0.94 0.56 0.67
0.44 0.44 0.50 0.41 0.20 0.24 0.14 0.23 0.67 .
8.25 7.95 7.29 10.66 3.36 3.59 2.43 5.00 2.61 . 4.00 5.79 4.33 4.94 5.29 5.14
. 0.31 0.25 0.33 0.28 0.20 0.24
NOr -N
NH2- - N
6.88 4.12 4.40 7.83 3.98 3.14 2.58 3.83 2.22
0.32 0.81 0.46 0.37 0.86 0.54 1.25 1.71 1.83
3.45 4.30 4.10 3.79 4.18 4.70
0.25 0.81 0.55 0.46 0.59 0.72
0.04 0.08 0.16 0.03 0.31 0.13 0.14 0.08 0.46 . 0.06 0.13 0.11 0.24 0.13 0.06
TABLE 2B Mean nutrient concentrations in the Western Gulf; water column averages in gg-at I - I. Cruise
pOi3-P SSP- 2 SSP- 7 SSP- 8 SSP- 9 SSP-10 SSP-11 SSP-12 SSP-13 SSP-14 SSP-15 SSP-16 SSP-17 SSP-18 SSP-19 SSP-20 SSP-21
54
Jan. 73 Oct. 73 Dec. 73 Feb. 74 Apr. 74 Jun. 74 Nov. 74 Dec. 74 Feb. 75 Apr. 75 Jun. 75 Sept. 75 Dec. 75 Mar. 76 Jun. 76 Sept. 76
Depths 300-400 m
Depths 200-300 m
Date
0.76 0.79 0.47 0.43 0.42 0.20 0.28 0.23 0.38 . 0.24 . 0.31 0.37 0.32 0.26
SiO~-4-Si NO~- - N 9.09 10.13 10.89 12.46 2.40 3.01 4.36 4.76 1.89 . 3.29 . 3.95 10.50 6.95 5.80
0.04 0.04 0.07 0.01 0.11 0.29 0. l I 0.05 0.26 .
. 0.03
.
. 0.11 0.29 0.10 0.02
N O ~ - - N NH4~ - N P O ~ - 3 - P SiO~-4-Si N O ~ - - N NO~- - N 9.52 5.66 3.87 7.64 7.83 5.44 4.99 4.13 1.94 . 3.15 . 4.18 6.50 5.43 4.90
0.01 0.14 0.33 0.34 1.40 1.95 1.33 0.80 2.54 . 0.15 . 0.59 0.50 0.17 0.37
1.33 0.62 0.88 0.81 0.58 0.19 . 0.34 0.51 .
17.25 12.11 25.69 28.33 3.20 2.28 .
. 0.26
.
. 0.30 0.36 0.30 0.28
. 7.58 1.98 . 4.39 . 4.22 7.26 7.30 7.00
0.04 0.00 0.05 0.03 0.43 0. l 1 . 0.10 0.32 . 0.06 . 0.11 0.11 0.12 0.02
NH2 -N
12.54 5.73 5.76 10.63 8.29 2.57
0.08 0.48 0.00 0.33 1.35 ! .30
4.98 1.76
2.25 3.16
2.94
0.22
4.05 3.70 4.97 5.31
0.47 0.24 0.27 0.39
.
Volume 14/Number 2/February 1983
TABLE 3 Total nutrients by cruise in the Western Gulf in g-at x 106 NH~" - N % Cruise
Date
PO~- 3 _ p
SiO~- 4 _ Si
NOr - N
NOj- - N
SSP- 2 SSP- 7 SSP- 8 Means
Jan. 73 Oct. 73 Dec. 73 1973
51.55 43.43 48.59 47.87
855.27 712.94 722.25 763.49
16.84 15.68 24.65 19.06
500.80 396.57 349.77 415.71
SSP- 9 SSP-10 SSP-I I SSP-12 SSP-I 3 Means
Feb. 74 Apr. 74 Jun. 74 Nov. 74 Dec. 74 1974
34.74 32.80 32.03 19.70 31.06 30.07
947.36 403.87 322.95 328.79 426.34 485.86
15.98 32.16 27.64 21.61 15.45 22.57
SSP-14 SSP-15 SSP-16 SSP-17 SSP-18 Means
Feb. 75 Apr. 75 Jun. 75 Sep. 75 Dec. 75 1975
106.08 . 33.14 19.34 38.51 49.26
SSP-19 SSP-20 SSP-21 Means
Mar. 76 Jun. 76 Sep. 76 1976
Background*
343.63
~N
5-N
61.88 107.33 68.97 79.39
579.52 519.58 443.39 514.36
10.7 20.7 15.4 15.7
604.89 603.99 421.13 358.01 299.61 457.54
85.88 109.12 125.63 203.89 281.98 16 I. 30
706.75 745.24 574.40 583.51 597.04 641.41
12.1 14.6 22.0 34.9 47.2 26.2
334.91 . 47.21 138.90 96.34 i 54.34
623.86
53.7
324.16 399.90 429.84 444.44
14.6 34.7 22.4 31.4
322.60 348.48 365.42 345.03
10.78 29.91 15.82 28.96
229.64 . 266.17 231.09 317.68 261.15
35,68 24.09 23.90 27.88
694.83 507.89 464.89 555.87
66.14 22.50 8.73 32.46
467.18 372.49 374.71 404.79
106.52 74.94 93.25 91.57
639.84 469.93 476.69 528.82
16.7 16.0 19.6 17.4
17.26
175.48
23.01
60.41
51.78
135.20
38.31
.
59.31
NH,~ - N
.
.
.
*Value obtained by multiplying mean concentrations of 1-100m. Outer Gulf Water by volume of basin under consideration (Table l).
Furthermore, this renewal can be attributed, apart from the observed decreased values of silicate by 1/3, to the seasonal variation of dissolved oxygen and density in depths below 300 m at the Epidavros station (JA). From January 1973 to February 1974, the values of oxygen varied from 2.7 to 3.8 ml l-' at the greatest depths of the station, while from April, oxygen increased to reach the maximum value of 5 ml l-' in June 1974. The density for depths below 300 m at the Epidavros station, after being constant, increased by 0.2 o, between February and April. The seasonal variation trend shows that phosphate, silicate and nitrate (Table 3) generally increased during winter and decreased during summer and autumn.
Ammonia generally reached high values in autumn. The nitrite pattern was rather confused, with a distinct maximum in February 1975, like ammonia and phosphate, the ratio NH~" - N : 5 N was high during the autumn period of the years 1973-1976. In Table 4 the ratios of total nutrients to phosphate are presented for each cruise. The criterion used in this analysis is that the normal N:Si:P ratio for diatoms is about 15:15:1 (Richards, 1965). The ratio YN:P presented increased values in 1974, compared to the other years, due to increased values of inorganic nitrogen during 1974. The ratio Si:P generally presented, for the years 1973-1975, a gradual decrease with time, due to the decrease of silicate,
TABLE 4 Ratios of total nutrient to phosphate, by atoms in Western Gulf. Cruise
Date
PO~- - P
SiO~-4 - Si
NO2- - N
NOj- - N
NH~- N
IN
SSP- 2 SSP- 7 SSP- 8 Means
Jan. 73 Oct. 73 Dec. 73 1973
I 1 I
16.5 16.4 14.9 15.9
0.3 0.4 0.5
9.7 9.1 7.2
1.2 2.5 1.4
I 1.2 12.0 9.1 10.8
SSP- 9 SSP-10 SSP-I I SSP-12 SSP- 13 Means
Feb. 74 Apr. 74 .fun. 74 Nov. 74 Dec. 74 1974
1 I 1 1 1
27.3 12.3 10.0 16.6 13.7 16.0
0.5 1.0 0.9 1.1 0.5
17.4 18.4 13.2 18.2 9.6
2.5 3.3 3.9 10.3 9.1
20.4 22.7 18.0 29.6 19.2 22.0
SSP-14 SSP- 15 SSP-16 SSP-17 SSP-18 Means
Feb. 75 Apr. 75 Jun. 75 Sept. 75 Dec. 75 1975
1 . 1 1 1
3.2
6.0
SSP-19 SSP-20 SSP-21 Means Overall means 2-21
Mar. 76 Jun. 76 Sep. 76 1976
1 I I
3.2 .
0.6 .
2.2 .
.
.
9.7 18.0 9.5 10.1
0.3 1.5 0.4
8.0 11.9 8.2
1.4 7.2 2.5
9.8 20.7 11.2 11.9
19.5 21.1 19.5 20.0
1.9 0.9 0.4
13.1 15.5 15.7
3.0 3.1 3.9
18.2 19.5 20.0 19.2
15.2
16.5
55
Marine Pollution Bulletin
TABLE 5 Ratios of total nutrient per cruise to background nutrient, in the Western Gulf. Cruise
Date
PO~-3 _ p
SiO~-4 _ Si
NO~- - N
NO 3- - N
NH~- - N
IN
SSP- 2 SSP- 7 SSP- 8 Means
Jan. 73 Oct. 73 Dec. 73 1973
2.99 2.52 2.82 2.77
4.87 4.06 4.12 4.35
0.73 0.68 1.07 0.83
8.29 6.56 5.79 6.88
1.20 2.07 1.33 1.53
4.29 3.84 3.28 3.8 I
SSP- 9 SSP-10 SSP-11 SSP-12 SSP-I 3 Means
Feb. 74 Apr. 74 Jun. 74 Nov. 74 Dec. 74 1974
2.01 1.90 1.86 1.14 1.80 1.74
5.40 2.30 1.84 1.87 2.43 2.77
0.69 1.40 1.20 0.94 0.67 0.98
10.01 10.00 6.97 5.93 4.96 7.57
1.66 2.11 2.43 3.94 5.45 3.12
5.24 5.51 4.26 4.32 4.42 4.75
SSP-14 SSP-15 SSP-16 SSP-17 SSP- 18 Means
Feb. 75 Apr. 75 Jun. 75 Sept. 75 Dec. 75 1975
6.14 . 1.92 1.12 2.23 2.85
6.47
4.61
0.91 2.68 1.86 2.98
2.40 2.96 3.18 3.29
SSP-19 SSP-20 SSP-21 Means
Mar. 76 Jun. 76 Sept. 76 1976
Overall means 2-21
1.96 1.84 1.99 2.08 1.97
0.47 1.30 0.69 1.26
3.80 . 4.41 3.82 5.26 4.32
2.07 1.40 1.38 1.62
3.95 2.88 2.64 3.16
2.87 0.98 0.38 1.41
7.72 6.17 6.20 6.70
2.06 1.45 1.80 1.77
4.72 3.48 3.53 3.91
2.25
2.95
1.11
6.39
2.50
4.00
.
while in 1976, the ratio Si:P presented higher values due to greater silicate concentrations. Nevertheless, the mean values of all the years 1973-1976 of the ratios ~-N:P and Si:P were of the order of 16 and 15, respectively, and can be considered as normal. The tendency of the water of the Western Gulf to accumulate nutrients above the background level is shown more clearly in Table 5, where the data of Table 3 have been reduced to ratios of total nutrient to background level. The Western Gulf contained four times more inorganic nitrogen than the background. This was mainly due to the nitrate, which was about six times more than the background value. Ammonia and nitrate were 2.5 and 1.0 times, respectively, above background. Furthermore, phosphate and silicate were, respectively, about 2 and 3 times above the background. Friligos (1981, 1982) reported the level of enrichment by inorganic nutrients in Elefsis Bay and in the Inner Gulf during the same cruises following the same methodology. He found that the Elefsis Bay contained nine times inorganic nitrogen than the background. This was mainly due to the ammonia being 15 times more than the background value. Nitrate and nitrite were in quantities greater by 7 and 3 times, respectively, above background. Furthermore, phosphate and silicate were, respectively, about 5 and 4 times above background. Also, he found that the Inner Gulf contained 3 times more inorganic nitrogen than background. This was mainly due to the ammonia which was about 4 times above background. Furthermore, phosphate and silicate were, respectively, about 2.5 and 1.5 times above background values. The Inner Gulf and Western Gulf appear to hold phosphate about equally. However, the tendency for silicate to be depleted in the Inner Gulf is again clear, while the Western Gulf tends to accumulate silicate more than phosphate. Nitrate tends to be accumulated even more than silicate in the Western Gulf, to about 6 times the background. An additional difference in the gross features of the nutrient budgets of the two basins is the tendency 56
2.58 .
.
.
for ammonia concentrations to compare with nitrate in the Inner Gulf, and for nitrate to predominate over ammonia in the Western Gulf. Elefsis Bay shows a tendency to concentrate all nutrients, but especially inorganic nitrogen. This was mainly due to the different sources of nutrients in Elefsis Bay (sewage, industrial effluents and anoxic conditions in summer) and in the Inner Gulf (sewage), as well as the morphology of each area and the circulation of the waters. The challenging but really difficult questions of this research lie in the area of prediction. The advent of a rapidly altered ecosystem is being observed. To a certain extent these changes are directly correlated to the increase of the urban waste discharge of the Athens Metropolitan area. On first thought, one would expect that diminishing the discharge at some future date would likewise diminish the marine pollution problem. On closer scrutiny, one finds that after a certain exposure many of these pollution processes are irreversible or only slowly reversible. For example, the generation of an anoxic basin in Epidavros Bay, a sulphide pond in Elefsis, would have serious long-term consequences. Nearly all marine-related activities will be vitally affected by one or more of those marine ecosystem changes. One exceedingly critical factor now under consideration is the location and design of a new marine outfall for the area. The major concern of the present marine research into Saronikos is to provide sufficient data, process description, and predictive capability to facilitate sound engineering and managerial decisions regarding the future of the Saronikos.
Coachman, L. K. & Hopkins, T. S. (1975). Description, analysis and conclusions on water masses of the Saronikos Gulf. Report to the Greater Athens Environmental Pollution Control Project. Dugdale, R. C. & Maclsaac, J. J. (1975). Interpretation of 02 nutrients and primary and secondary production data. Report to the Greater Athens Environmental Pollution Control Project. Friligos, N. (1976). On eutrophication in the Western Basin of the Saronikos Gulf, January 1973. Thalassia Yugosl., 12, 455---462.
Volume 14/Number 2/February 1983 Friligos, N (1979). An index of marine pollution in the Saronikos Gulf. Mar. Pollut. Bull, 12, 96-100. Friligos, N. (1981). Enrichment by inorganic nutrients and oxygen utilization rates in Elefsis Bay (1973-1976). Mar. Pollut. Bull, 12, 431--436. Friligos, N. (1982). Enrichment of inorganic nutrients in the Inner Saronikos Gulf (1973-1976). Mar. Pollut. Bull, 13, 154-158.
Hopkins, T. S. (1974). A discussion of the marine pollution problems in the Saronikos Gulf as disclosed by current research. Technical report 3, IQKAE. Richards, F. A. (1965). Anoxic basins and fjords. In Chemical Oceanography (J. P. Riley & G. Skirrow, eds), Vol. 1, pp. 611-645. Academic Press, New York.
Marine Pollution Bulletin, Vol. 14, No. 2, pp. 57-60, 1983 Primed in Great Britain
0025-326X/83/020057-04$03.00/0 1983 Pergamon Press Ltd.
Burrowing and Avoidance Behaviour in Marine Organisms Exposed to Pesticidecontaminated Sediment FLEMMING M O H L E N B E R G and THOMAS KIORBOE* Marine Pollution Laboratory, National Agency of Environmental Protection, Kavalergi~rden 6, DK-2920 Charlottenlund, Denmark *Present address: R oskilde University Center, Institute o f Biology, P. O. Box 260, DK-4000 R oskilde, Denmark
Behavioural effects of marine sediment contaminated with pesticides (6000 ppm parathion, 200 ppm methyl parathion, 200 ppm malathion) were studied in a number of marine organisms in laboratory tests and /n s/tu. The burrowing behaviour in Macoma balaca, Cerastodenna edule, Abra alba, Nereis diversicolor and Scoloplos arm/get was impaired in the contaminated sediment compared to control. The impairment was most pronounced in the laboratory tests, where almost no burrowing occured. In a very simple laboratory set-up, highly significant avoidance of the contaminated sediment was demonstrated for Crangon crangon and Solea solea, but not for Carc/nus maenas and Pomatoschistus minutus. The validity of both behavioural tests was supported by/!1 s/tu observations and investigations on the distribution of the species. It is concluded that both tests are useful tools in the assessment of the impact of contaminated sediments. The ability of marine organisms to sense certain pollutants is well documented (e.g. Olla et ai., 1980), even though the mechanisms involved are poorly understood. Chemical pollutants in the sea may cause changes in animal behaviour and may lead to avoidance of the pollutant. Compared to effect studies on physiology and metabolism, only minor attention has been paid to the effects of pollutants on behaviour, even though they may be of crucial importance in the overall assessment of the effects of the pollutants (McIntyre & Pearce, 1980). Previous studies have shown that normal burrowing behaviour in the deposit-feeding bivalves Macoma baltica and Tellina tenuis become impaired when the bivalves are exposed to heavy metals, oil or phenol (Stephenson & Taylor, 1975; Stirling, 1975; Linden, 1977; Eldon & Kristoffersson, 1978; McGreer, 1979; Eldon et aL, 1980). In most of these studies the sediment was clean and the pollutants were added to the water; hence the situation bore little resemblance to many pollution incidents in nature. This work reports on the effects of pesticide and herbi-
cide-contaminated sediments on the burrowing behaviour in a number of infaunal polychaetes and bivalves in the laboratory as well as in situ. Further, tests on avoidance behaviour in crustaceans and fish were carried out in the laboratory and the results compared to catches of fish in the contaminated area.
Materials and Methods Laboratory experiments were carried out during August 1981 at the Marine Biological Station, RCnbjerg, Denmark. Test sediment (sand with an organic content of about 1°70) was collected in the littoral zone close to a demolished chemical plant formerly (1953-1962) producing pesticides, herbicides and mercury-containing fungicides. The plant was located at HarboCre Tange in the western part of Limfjorden, Denmark. Recently, a substantial ooze-out of waste products deposited in the basement of the demolished plant and contamination of the littoral sediment close to the plant was observed by the authorities. Control sediment came from an uncontaminated part of the littoral zone near the plant. After termination of the behavioural tests the sediments were stored at 0°C until chemical analysis. Concentration of contaminants in the test sediment are given in Table 1.
Burrowing behaviour Burrowing behaviour was tested in perspex aquaria (22 × 30 x 12 cm) filled to 5 cm depth with sediment. Sediment was either the contaminated test sediment (A), control sediment (C) or test sediment diluted to one-tenth by control sediment (B). At least 1 h prior to and during the tests, each aquarium received a continuous throughflow of sea water from the laboratory system at a rate of approx. 100 ml min -1. Salinity (25°,) and temperature (17°C) were similar to the conditions at the animal collecting site. Test organisms were Cerastoderma edule (15-30 mm), Abra alba (10-15 mm), Macoma baltica (12-25mm), Nereis diversicolor and Scoloplos armiger. All organisms were collected in the same area as the 57
American Public Health Association (1971). Standard Methods for the Examination o f Water and Wastewater, 13th Edition. American Public Health Association, Washington, D.C. Anger, K. (1975). On the influence of sewage pollution on inshore benthic communities in the South of Kiel Bay. Part 2. Quantitative studies on community structure. Helgoltlnder wiss. Meeresunters., 27, 408-438. Bagge, P. (1969). Effects of pollution on estuarine ecosystems-l. Effects of effluents from wood-processing industries on the hydrography, bottom and fauna of Saltkallefjord (W. Sweden). Merentutkimuslait. Julk./Havsforsk Inst. Skr., Helsingf., 228, 3-118. Ganapati, P. N. (1969). Biology of pollution in Visakhapatnam Harbour. Mar. Poilu& Bull., No. 16: 1-3. Ganapati, P. N. & Raman, A. V. (1973). Pollution in Visakhapatnam Harbour. Curr. Sci., 42, 490-492. Ganapati, P. N. & Raman, A. V. (1979). Organic pollution and Skeletonema blooms in Visakhapatnam Harbour. Indian J. mar. Sci., 8, 184-187. Leppakoski, E. (1975). Assessment of degree of pollution on the basis of macroznohenthos in marine and brackish-water environments.
Acta. Acad. .~bo. Ser. B. Math. Phys. Mat. Naturvetensk. Tek., 35, 1-90.
Mare, M. F. (1942). A study of marine benthic community with special reference to the microorganisms. J. mar. biol. Ass. U.K., 25, 517-554. Parrish, L. P. & Mackenthun, K. M. (1968). U.S. Department of the Interior. San Diego Bay: A n evaluation o f the benthic environment. Federal Water Pollution Control Administration, Technical Advisory and Investigations Branch Report (5555, Ridge Ave., Cincinnati, Ohio), 31 pp. Pearson, T. H. & Rosenberg, R. (1978). Macrobenthic succession in relation to organic enrichment and pollution of the marine environment. Oceanogr. mar. Biol. A. Rev., 16, 229-31 I. Reish, D. J. (1959). An ecological study of pollution in Los AngelesLong Beach harbors, California. Occ. Pap. Allan Hancock Fdn. 22, 1-119. Remane, A. (1971). Ecology of brackish water. In Biology o f Brackish water (A. Remane and C. Schlieper, eds.), pp. 1-180. John Wiley, New York. Rosenberg, R. (1975). Stressed tropical faunal communities off Miami, Florida. Ophelia, 14, 93-112. Sanders, H. L. 0968). Marine benthic diversity: A comparative study. Am. Nat., 102, 243-282. Wade, B. A. (1976). The pollution ecology of Kingston Harbour, Jamaica: I I. Benthic ecology. Scientific Report of the U. W.I. -0. D. M. Kingston Harbour Research Project, 1972-1975. 104 pp.
MarinePollutionBulletin,Vol.14,No.2, pp. 52-57,1983 PrintedinGreatBritain
0025-326X/83/020052--06$03.00/0 1983PergamonPressLtd.
Enrichment of Inorganic Nutrients in the Western Saronikos Gulf N. FRILIGOS
Institute of Oceanographic and Fisheries Research, Athens, Greece Studies of nutrient enrichment in the Western Saronikos Gulf for the period 1973-1976 are presented here. Also, a comparison of nutrient enrichment is made between the Western and Inner Gulfs and Elefsis Bay. The Western Gulf and Inner Gulf appear to hold phosphate equally. However, the tendency for silicate to be depleted in the Inner Gulf is clear, while the Western Gulf tends to accumulate silicate more than phosphate. Nitrate tends to be accumulated even more than silicate in the Western Gulf. Elefsis Bay accumulated more nutrients than the other gulfs, especially inorganic nitrogen. This was mainly due to the different sources of nutrients as well as the morphology of each area and the circulation of the waters. The water masses of the Western Gulf were renewed in Spring 1974, as can be seen from the silicate values which fell by 1/3. Nutrient ratios in the Western Gulf were close to normal.
Saronikos Gulf, the marine gateway to the metropolitan Athens area of Greece, invites the attention of marine scientists because eutrophication and other alterations are occurring in its naturally oligotrophic waters as a consequence of urban waste disposal. Domestic sewage contains a great amount of nutrients, especially chemical compounds with nitrogen and phosphorus, and consequently produces an increase in eutrophication. This manmade eutrophication can be measured in its occurrence and geographic extent by measurements of nutrients. This paper presents the chemical results found from 1973 to 1976 in the Western Saronikos Gulf. More specifically, 52
this paper examines the nutrient enrichment in the Western Saronikos Gulf from the baseline values outside the Saronikos Gulf to those values found in areas influenced by the sewage outfall and industrial effluents at the apex of the Gulf. Prior to these studies, the seasonal variation of the spatial distribution and the relationship between nutrients in the Western Saronikos Gulf had only been studied over relatively short periods, or at a limited number of stations (Dugdale & MacIsaac, 1975; Friligos, 1976).
Material and Methods The sampling area was the western part of the Saronikos Gulf, Aegean Sea, whose topography has been described elsewhere (Friligos, 1982). Stations FA, HA, JA, N, D, CA, BA (Fig. 1) were chosen in the Western Saronikos Gulf following the results and terminology used in the water masses report (Coachman & Hopkins, 1975). Samples of water were collected from 1, 10, 20, 50, 75,100, 125, 150, 200, 250, 300, 350 and 400 m using Nansen reversing water samplers. The sampling was done at seasonal intervals during 1973-1976. It should be noticed that investigations on nutrients were carried out in the Western and Inner Gulfs and Elefsis Bay during the same cruises. Measurements of inorganic nutrients were made by methods described by Friligos (1979). The same methodology was followed for calculating the level of enrichment by inorganic nutrients as in the case
Volume 14/Number 2/February 1983
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Fig. 1 Location of the stations, oceanographic subregions and bathymetry of the Saronikos Gulf.
of the Elefsis Bay (Friligos, 1981) and the Inner Gulf (Friligos, 1982).
Results and Discussion The western part of Saronikos Gulf is the deeper. From west of Salamis to the Korinthos-Loutraki land bridge the basin is 130 m, which connects to the south with a deep (~400m) depression in Epidavros basin. The western Saronikos Gulf receives only biologically filtered or chemically altered pollutants from the sewage outfall. Some of the characteristics of the sewage have been described elsewhere (Friligos, 1982). Hopkins (1974) reported that the Western Basin, with its stagnant or partly stagnant conditions, is especially sensitive to pollution due to slow water exchange. Such an area presents a neutrally stable condition in winter which causes the formation of a light surface water layer, which isolates the heavier deep water from contact with the atmosphere. Two shallow sills, one in the north between Salamis and Aegina, with a sill depth of about 100 m, and the other to the south between Aegina and the Methanon peninsula, with a sill depth of 80 m, restrict the horizontal water exchange. Dugdale & MacIsaac (1975) and Friligos (1976) reported that this basin acts as a nutrient trap. Nutrients are removed from the surface water through uptake by microorganisms. When these organisms die, the whole or a part of tfiem sinks through the halocline into deep water. Through bacterial oxidation processes the nutrients of these organisms revert to the inorganic form and are dissolved. Figure 2 shows a comparison between vertical distribution of oxygen, nitrate and silicate in Epidavros (st. JA) and in the Aegean water just out from the Saronikos. The nutrient accumulation and oxygen depletion are obvious. The fact that such vertical gradients exist
throughout the neutrally stable conditions of winter suggests that the bottom waters are convectively not flushed annually. For most of the year the deep waters gain oxygen and nutrients through the weak process of vertical diffusion. With an increased organic load from the Athens outfall, it is only a matter of time before Epidavros Basin becomes anoxic, resulting in very serious consequences to the surrounding fisheries. The total nutrient of the Western Gulf was determined for sixteen cruises SSP 2-SSP 21 (January 1973-September 1976). From Fig. 1 it can be seen that in the Western Gulf
mr/L,
,u.g-a'(IL JO
I 50
\
--- - February74,Epidovros March,Saronikosmouth
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ioo ~. E
15
,\\ \\
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t~ 200 ~-/
II
"~\N ',\
\\
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Fig. 2 Oxygen (in ml I - I), nitrate (in ~g-at I - ]) and silicate (in ~g-at 1- 1) comparison between Epidavros Basin and the Aegean just south of Saronikos.
53
Marine Pollution Bulletin
most sample line in the Eastern Gulf. All available SSP data were used in the calculation and these values were quoted by Friligos (1981) in Table 3. Mean nutrient concentrations for cruises SSP-2 and 7-21 are shown in Tables 2a and 2b for the Western Gulf, subdivided by depth ranges. The concentration of silicate and nitrate are often considerably above the background levels of Table 3 (Friligos, 1981), where accumulation of nutrient in the deep water is apparent. Mean concentrations for the various depths and cruises as shown in Tables 3 (Friligos, 1981) and 2a, 2b were multiplied by the appropriate volumes given in Table 1 to obtain an estimate of total nutrient held in dissolved form in the Western Gulf. The results are presented in Table 3 along with background values. The latter were computed from the mean concentrations for the Outer Gulf water (Table 3; Friligos, 1981) and the appropriate volumes (Table 1). All five nutrients are present in all areas at levels well above background. From these data it appears that total nutrients do not vary widely from cruise to cruise, although after SSP-8 the amounts of silicate and phosphate declined, while total inorganic nitrogen increased. Between cruises 8 and 11 (December 1973-June 1974), there was massive transport of deep Western Gulf water (Coachman & Hopkins, 1975), probably the cause of such changes.
TABLE 1 Volumes of Western Gulf. Total surface = 1 i 17 x 106 m 2. Depth interval (m)
V( x l06 m 3)
0-100 100-200 200-300 300--400 400-428 Total
85 287 39 859 13 878 4518 294 143 836
there is a considerable area with depths below 100 m, providing the possibility for trapping of nutrients. The Epidavros depression has a maximum depth of more than 400 m. The approximate volumes of the respective basin, divided into appropriate depth ranges, are given in Table 1. Current levels of circulatory nutrients were estimated by computing mean values for the depth intervals indicated in Table 2a and 2b, station by station (FA, HA, JA, N, D, CA, BA), and combining these to give mean values. The mean values were multiplied by the appropriate volumes to give quantitative estimates of total nutrients contained in the basin (Table 3). The mean values for the Outer Gulf water, the source water for the region, were obtained from 0-100m samples at stations LA, MA and NA, located along the southern-
TABLE 2A Mean nutrient concentrations in the Western Gulf; water column averages in ~g-at I - I Cruise
Date
PO4-3p SiO~-4-Si NO~- - N SSP- 2 SSP- 7 SSP- 8 SSP- 9 SSP-10 SSP-I l SSP-12 SSP-13 SSP-14 SSP-15 SSP-16 SSP-17 SSP-18 SSP-19 SSP-20 SSP-21
Jan. 73 Oct. 73 Dec. 73 Feb. 74 Apr. 74 Jun. 74 Nov. 74 Dec. 74 Feb. 75 Apr. 75 Jun. 75 Sept. 75 Dec. 75 Mar. 76 Jun. 76 Sept. 76
Depths 100-200 m
Depths 0-100 m
0.20 0.14 0.21 0.10 0.19 0.22 0.12 0.20 0.84 . 0.19 0.11 0.23 0.20 0.12 0.11
3.72 2.31 1.84 2.50 2.47 1.42 2.01 1.46 2.39 .
0.17 0.14 0.20 0.17 0.19 0.21 0.17 0.13 0.42 .
1.13 1.38 1.38 3.72 1.94 1.71
. 0.09 0.29 0.11 0.61 0.18 0.07
NO~- - N 0.40 1.48 1.09 1.59 3.48 2.44 2.18 0.77 1.24 . 0.83 0.70 0.90 2.44 1.25 1.10
NH~- - N P O ~ - 3 - P SiO~-4-Si NO~- - N 0.57 0.83 0.54 0.76 0.63 0.83 1.59 2.25 2.48 . 0.40 1.25 0.75 0.94 0.56 0.67
0.44 0.44 0.50 0.41 0.20 0.24 0.14 0.23 0.67 .
8.25 7.95 7.29 10.66 3.36 3.59 2.43 5.00 2.61 . 4.00 5.79 4.33 4.94 5.29 5.14
. 0.31 0.25 0.33 0.28 0.20 0.24
NOr -N
NH2- - N
6.88 4.12 4.40 7.83 3.98 3.14 2.58 3.83 2.22
0.32 0.81 0.46 0.37 0.86 0.54 1.25 1.71 1.83
3.45 4.30 4.10 3.79 4.18 4.70
0.25 0.81 0.55 0.46 0.59 0.72
0.04 0.08 0.16 0.03 0.31 0.13 0.14 0.08 0.46 . 0.06 0.13 0.11 0.24 0.13 0.06
TABLE 2B Mean nutrient concentrations in the Western Gulf; water column averages in gg-at I - I. Cruise
pOi3-P SSP- 2 SSP- 7 SSP- 8 SSP- 9 SSP-10 SSP-11 SSP-12 SSP-13 SSP-14 SSP-15 SSP-16 SSP-17 SSP-18 SSP-19 SSP-20 SSP-21
54
Jan. 73 Oct. 73 Dec. 73 Feb. 74 Apr. 74 Jun. 74 Nov. 74 Dec. 74 Feb. 75 Apr. 75 Jun. 75 Sept. 75 Dec. 75 Mar. 76 Jun. 76 Sept. 76
Depths 300-400 m
Depths 200-300 m
Date
0.76 0.79 0.47 0.43 0.42 0.20 0.28 0.23 0.38 . 0.24 . 0.31 0.37 0.32 0.26
SiO~-4-Si NO~- - N 9.09 10.13 10.89 12.46 2.40 3.01 4.36 4.76 1.89 . 3.29 . 3.95 10.50 6.95 5.80
0.04 0.04 0.07 0.01 0.11 0.29 0. l I 0.05 0.26 .
. 0.03
.
. 0.11 0.29 0.10 0.02
N O ~ - - N NH4~ - N P O ~ - 3 - P SiO~-4-Si N O ~ - - N NO~- - N 9.52 5.66 3.87 7.64 7.83 5.44 4.99 4.13 1.94 . 3.15 . 4.18 6.50 5.43 4.90
0.01 0.14 0.33 0.34 1.40 1.95 1.33 0.80 2.54 . 0.15 . 0.59 0.50 0.17 0.37
1.33 0.62 0.88 0.81 0.58 0.19 . 0.34 0.51 .
17.25 12.11 25.69 28.33 3.20 2.28 .
. 0.26
.
. 0.30 0.36 0.30 0.28
. 7.58 1.98 . 4.39 . 4.22 7.26 7.30 7.00
0.04 0.00 0.05 0.03 0.43 0. l 1 . 0.10 0.32 . 0.06 . 0.11 0.11 0.12 0.02
NH2 -N
12.54 5.73 5.76 10.63 8.29 2.57
0.08 0.48 0.00 0.33 1.35 ! .30
4.98 1.76
2.25 3.16
2.94
0.22
4.05 3.70 4.97 5.31
0.47 0.24 0.27 0.39
.
Volume 14/Number 2/February 1983
TABLE 3 Total nutrients by cruise in the Western Gulf in g-at x 106 NH~" - N % Cruise
Date
PO~- 3 _ p
SiO~- 4 _ Si
NOr - N
NOj- - N
SSP- 2 SSP- 7 SSP- 8 Means
Jan. 73 Oct. 73 Dec. 73 1973
51.55 43.43 48.59 47.87
855.27 712.94 722.25 763.49
16.84 15.68 24.65 19.06
500.80 396.57 349.77 415.71
SSP- 9 SSP-10 SSP-I I SSP-12 SSP-I 3 Means
Feb. 74 Apr. 74 Jun. 74 Nov. 74 Dec. 74 1974
34.74 32.80 32.03 19.70 31.06 30.07
947.36 403.87 322.95 328.79 426.34 485.86
15.98 32.16 27.64 21.61 15.45 22.57
SSP-14 SSP-15 SSP-16 SSP-17 SSP-18 Means
Feb. 75 Apr. 75 Jun. 75 Sep. 75 Dec. 75 1975
106.08 . 33.14 19.34 38.51 49.26
SSP-19 SSP-20 SSP-21 Means
Mar. 76 Jun. 76 Sep. 76 1976
Background*
343.63
~N
5-N
61.88 107.33 68.97 79.39
579.52 519.58 443.39 514.36
10.7 20.7 15.4 15.7
604.89 603.99 421.13 358.01 299.61 457.54
85.88 109.12 125.63 203.89 281.98 16 I. 30
706.75 745.24 574.40 583.51 597.04 641.41
12.1 14.6 22.0 34.9 47.2 26.2
334.91 . 47.21 138.90 96.34 i 54.34
623.86
53.7
324.16 399.90 429.84 444.44
14.6 34.7 22.4 31.4
322.60 348.48 365.42 345.03
10.78 29.91 15.82 28.96
229.64 . 266.17 231.09 317.68 261.15
35,68 24.09 23.90 27.88
694.83 507.89 464.89 555.87
66.14 22.50 8.73 32.46
467.18 372.49 374.71 404.79
106.52 74.94 93.25 91.57
639.84 469.93 476.69 528.82
16.7 16.0 19.6 17.4
17.26
175.48
23.01
60.41
51.78
135.20
38.31
.
59.31
NH,~ - N
.
.
.
*Value obtained by multiplying mean concentrations of 1-100m. Outer Gulf Water by volume of basin under consideration (Table l).
Furthermore, this renewal can be attributed, apart from the observed decreased values of silicate by 1/3, to the seasonal variation of dissolved oxygen and density in depths below 300 m at the Epidavros station (JA). From January 1973 to February 1974, the values of oxygen varied from 2.7 to 3.8 ml l-' at the greatest depths of the station, while from April, oxygen increased to reach the maximum value of 5 ml l-' in June 1974. The density for depths below 300 m at the Epidavros station, after being constant, increased by 0.2 o, between February and April. The seasonal variation trend shows that phosphate, silicate and nitrate (Table 3) generally increased during winter and decreased during summer and autumn.
Ammonia generally reached high values in autumn. The nitrite pattern was rather confused, with a distinct maximum in February 1975, like ammonia and phosphate, the ratio NH~" - N : 5 N was high during the autumn period of the years 1973-1976. In Table 4 the ratios of total nutrients to phosphate are presented for each cruise. The criterion used in this analysis is that the normal N:Si:P ratio for diatoms is about 15:15:1 (Richards, 1965). The ratio YN:P presented increased values in 1974, compared to the other years, due to increased values of inorganic nitrogen during 1974. The ratio Si:P generally presented, for the years 1973-1975, a gradual decrease with time, due to the decrease of silicate,
TABLE 4 Ratios of total nutrient to phosphate, by atoms in Western Gulf. Cruise
Date
PO~- - P
SiO~-4 - Si
NO2- - N
NOj- - N
NH~- N
IN
SSP- 2 SSP- 7 SSP- 8 Means
Jan. 73 Oct. 73 Dec. 73 1973
I 1 I
16.5 16.4 14.9 15.9
0.3 0.4 0.5
9.7 9.1 7.2
1.2 2.5 1.4
I 1.2 12.0 9.1 10.8
SSP- 9 SSP-10 SSP-I I SSP-12 SSP- 13 Means
Feb. 74 Apr. 74 .fun. 74 Nov. 74 Dec. 74 1974
1 I 1 1 1
27.3 12.3 10.0 16.6 13.7 16.0
0.5 1.0 0.9 1.1 0.5
17.4 18.4 13.2 18.2 9.6
2.5 3.3 3.9 10.3 9.1
20.4 22.7 18.0 29.6 19.2 22.0
SSP-14 SSP- 15 SSP-16 SSP-17 SSP-18 Means
Feb. 75 Apr. 75 Jun. 75 Sept. 75 Dec. 75 1975
1 . 1 1 1
3.2
6.0
SSP-19 SSP-20 SSP-21 Means Overall means 2-21
Mar. 76 Jun. 76 Sep. 76 1976
1 I I
3.2 .
0.6 .
2.2 .
.
.
9.7 18.0 9.5 10.1
0.3 1.5 0.4
8.0 11.9 8.2
1.4 7.2 2.5
9.8 20.7 11.2 11.9
19.5 21.1 19.5 20.0
1.9 0.9 0.4
13.1 15.5 15.7
3.0 3.1 3.9
18.2 19.5 20.0 19.2
15.2
16.5
55
Marine Pollution Bulletin
TABLE 5 Ratios of total nutrient per cruise to background nutrient, in the Western Gulf. Cruise
Date
PO~-3 _ p
SiO~-4 _ Si
NO~- - N
NO 3- - N
NH~- - N
IN
SSP- 2 SSP- 7 SSP- 8 Means
Jan. 73 Oct. 73 Dec. 73 1973
2.99 2.52 2.82 2.77
4.87 4.06 4.12 4.35
0.73 0.68 1.07 0.83
8.29 6.56 5.79 6.88
1.20 2.07 1.33 1.53
4.29 3.84 3.28 3.8 I
SSP- 9 SSP-10 SSP-11 SSP-12 SSP-I 3 Means
Feb. 74 Apr. 74 Jun. 74 Nov. 74 Dec. 74 1974
2.01 1.90 1.86 1.14 1.80 1.74
5.40 2.30 1.84 1.87 2.43 2.77
0.69 1.40 1.20 0.94 0.67 0.98
10.01 10.00 6.97 5.93 4.96 7.57
1.66 2.11 2.43 3.94 5.45 3.12
5.24 5.51 4.26 4.32 4.42 4.75
SSP-14 SSP-15 SSP-16 SSP-17 SSP- 18 Means
Feb. 75 Apr. 75 Jun. 75 Sept. 75 Dec. 75 1975
6.14 . 1.92 1.12 2.23 2.85
6.47
4.61
0.91 2.68 1.86 2.98
2.40 2.96 3.18 3.29
SSP-19 SSP-20 SSP-21 Means
Mar. 76 Jun. 76 Sept. 76 1976
Overall means 2-21
1.96 1.84 1.99 2.08 1.97
0.47 1.30 0.69 1.26
3.80 . 4.41 3.82 5.26 4.32
2.07 1.40 1.38 1.62
3.95 2.88 2.64 3.16
2.87 0.98 0.38 1.41
7.72 6.17 6.20 6.70
2.06 1.45 1.80 1.77
4.72 3.48 3.53 3.91
2.25
2.95
1.11
6.39
2.50
4.00
.
while in 1976, the ratio Si:P presented higher values due to greater silicate concentrations. Nevertheless, the mean values of all the years 1973-1976 of the ratios ~-N:P and Si:P were of the order of 16 and 15, respectively, and can be considered as normal. The tendency of the water of the Western Gulf to accumulate nutrients above the background level is shown more clearly in Table 5, where the data of Table 3 have been reduced to ratios of total nutrient to background level. The Western Gulf contained four times more inorganic nitrogen than the background. This was mainly due to the nitrate, which was about six times more than the background value. Ammonia and nitrate were 2.5 and 1.0 times, respectively, above background. Furthermore, phosphate and silicate were, respectively, about 2 and 3 times above the background. Friligos (1981, 1982) reported the level of enrichment by inorganic nutrients in Elefsis Bay and in the Inner Gulf during the same cruises following the same methodology. He found that the Elefsis Bay contained nine times inorganic nitrogen than the background. This was mainly due to the ammonia being 15 times more than the background value. Nitrate and nitrite were in quantities greater by 7 and 3 times, respectively, above background. Furthermore, phosphate and silicate were, respectively, about 5 and 4 times above background. Also, he found that the Inner Gulf contained 3 times more inorganic nitrogen than background. This was mainly due to the ammonia which was about 4 times above background. Furthermore, phosphate and silicate were, respectively, about 2.5 and 1.5 times above background values. The Inner Gulf and Western Gulf appear to hold phosphate about equally. However, the tendency for silicate to be depleted in the Inner Gulf is again clear, while the Western Gulf tends to accumulate silicate more than phosphate. Nitrate tends to be accumulated even more than silicate in the Western Gulf, to about 6 times the background. An additional difference in the gross features of the nutrient budgets of the two basins is the tendency 56
2.58 .
.
.
for ammonia concentrations to compare with nitrate in the Inner Gulf, and for nitrate to predominate over ammonia in the Western Gulf. Elefsis Bay shows a tendency to concentrate all nutrients, but especially inorganic nitrogen. This was mainly due to the different sources of nutrients in Elefsis Bay (sewage, industrial effluents and anoxic conditions in summer) and in the Inner Gulf (sewage), as well as the morphology of each area and the circulation of the waters. The challenging but really difficult questions of this research lie in the area of prediction. The advent of a rapidly altered ecosystem is being observed. To a certain extent these changes are directly correlated to the increase of the urban waste discharge of the Athens Metropolitan area. On first thought, one would expect that diminishing the discharge at some future date would likewise diminish the marine pollution problem. On closer scrutiny, one finds that after a certain exposure many of these pollution processes are irreversible or only slowly reversible. For example, the generation of an anoxic basin in Epidavros Bay, a sulphide pond in Elefsis, would have serious long-term consequences. Nearly all marine-related activities will be vitally affected by one or more of those marine ecosystem changes. One exceedingly critical factor now under consideration is the location and design of a new marine outfall for the area. The major concern of the present marine research into Saronikos is to provide sufficient data, process description, and predictive capability to facilitate sound engineering and managerial decisions regarding the future of the Saronikos.
Coachman, L. K. & Hopkins, T. S. (1975). Description, analysis and conclusions on water masses of the Saronikos Gulf. Report to the Greater Athens Environmental Pollution Control Project. Dugdale, R. C. & Maclsaac, J. J. (1975). Interpretation of 02 nutrients and primary and secondary production data. Report to the Greater Athens Environmental Pollution Control Project. Friligos, N. (1976). On eutrophication in the Western Basin of the Saronikos Gulf, January 1973. Thalassia Yugosl., 12, 455---462.
Volume 14/Number 2/February 1983 Friligos, N (1979). An index of marine pollution in the Saronikos Gulf. Mar. Pollut. Bull, 12, 96-100. Friligos, N. (1981). Enrichment by inorganic nutrients and oxygen utilization rates in Elefsis Bay (1973-1976). Mar. Pollut. Bull, 12, 431--436. Friligos, N. (1982). Enrichment of inorganic nutrients in the Inner Saronikos Gulf (1973-1976). Mar. Pollut. Bull, 13, 154-158.
Hopkins, T. S. (1974). A discussion of the marine pollution problems in the Saronikos Gulf as disclosed by current research. Technical report 3, IQKAE. Richards, F. A. (1965). Anoxic basins and fjords. In Chemical Oceanography (J. P. Riley & G. Skirrow, eds), Vol. 1, pp. 611-645. Academic Press, New York.
Marine Pollution Bulletin, Vol. 14, No. 2, pp. 57-60, 1983 Primed in Great Britain
0025-326X/83/020057-04$03.00/0 1983 Pergamon Press Ltd.
Burrowing and Avoidance Behaviour in Marine Organisms Exposed to Pesticidecontaminated Sediment FLEMMING M O H L E N B E R G and THOMAS KIORBOE* Marine Pollution Laboratory, National Agency of Environmental Protection, Kavalergi~rden 6, DK-2920 Charlottenlund, Denmark *Present address: R oskilde University Center, Institute o f Biology, P. O. Box 260, DK-4000 R oskilde, Denmark
Behavioural effects of marine sediment contaminated with pesticides (6000 ppm parathion, 200 ppm methyl parathion, 200 ppm malathion) were studied in a number of marine organisms in laboratory tests and /n s/tu. The burrowing behaviour in Macoma balaca, Cerastodenna edule, Abra alba, Nereis diversicolor and Scoloplos arm/get was impaired in the contaminated sediment compared to control. The impairment was most pronounced in the laboratory tests, where almost no burrowing occured. In a very simple laboratory set-up, highly significant avoidance of the contaminated sediment was demonstrated for Crangon crangon and Solea solea, but not for Carc/nus maenas and Pomatoschistus minutus. The validity of both behavioural tests was supported by/!1 s/tu observations and investigations on the distribution of the species. It is concluded that both tests are useful tools in the assessment of the impact of contaminated sediments. The ability of marine organisms to sense certain pollutants is well documented (e.g. Olla et ai., 1980), even though the mechanisms involved are poorly understood. Chemical pollutants in the sea may cause changes in animal behaviour and may lead to avoidance of the pollutant. Compared to effect studies on physiology and metabolism, only minor attention has been paid to the effects of pollutants on behaviour, even though they may be of crucial importance in the overall assessment of the effects of the pollutants (McIntyre & Pearce, 1980). Previous studies have shown that normal burrowing behaviour in the deposit-feeding bivalves Macoma baltica and Tellina tenuis become impaired when the bivalves are exposed to heavy metals, oil or phenol (Stephenson & Taylor, 1975; Stirling, 1975; Linden, 1977; Eldon & Kristoffersson, 1978; McGreer, 1979; Eldon et aL, 1980). In most of these studies the sediment was clean and the pollutants were added to the water; hence the situation bore little resemblance to many pollution incidents in nature. This work reports on the effects of pesticide and herbi-
cide-contaminated sediments on the burrowing behaviour in a number of infaunal polychaetes and bivalves in the laboratory as well as in situ. Further, tests on avoidance behaviour in crustaceans and fish were carried out in the laboratory and the results compared to catches of fish in the contaminated area.
Materials and Methods Laboratory experiments were carried out during August 1981 at the Marine Biological Station, RCnbjerg, Denmark. Test sediment (sand with an organic content of about 1°70) was collected in the littoral zone close to a demolished chemical plant formerly (1953-1962) producing pesticides, herbicides and mercury-containing fungicides. The plant was located at HarboCre Tange in the western part of Limfjorden, Denmark. Recently, a substantial ooze-out of waste products deposited in the basement of the demolished plant and contamination of the littoral sediment close to the plant was observed by the authorities. Control sediment came from an uncontaminated part of the littoral zone near the plant. After termination of the behavioural tests the sediments were stored at 0°C until chemical analysis. Concentration of contaminants in the test sediment are given in Table 1.
Burrowing behaviour Burrowing behaviour was tested in perspex aquaria (22 × 30 x 12 cm) filled to 5 cm depth with sediment. Sediment was either the contaminated test sediment (A), control sediment (C) or test sediment diluted to one-tenth by control sediment (B). At least 1 h prior to and during the tests, each aquarium received a continuous throughflow of sea water from the laboratory system at a rate of approx. 100 ml min -1. Salinity (25°,) and temperature (17°C) were similar to the conditions at the animal collecting site. Test organisms were Cerastoderma edule (15-30 mm), Abra alba (10-15 mm), Macoma baltica (12-25mm), Nereis diversicolor and Scoloplos armiger. All organisms were collected in the same area as the 57