Case Studies - Coastal Lagoons: Ecosystem Processes and Modeling for Sustainable Use and Development - page 448

the agents that increase nitrate input, usually after precipitation. Groundwater level
is high in Dalyan Lagoon, but there is a lack of information about nitrate input from
groundwater. Since nitrite (NO 2 − -N) concentrations are low, the majority of oxidized
nitrogen concentration consists of nitrate (NO 3 − -N). Total nitrogen (TN) concen-
trations were found to be high for surface and bottom waters, especially in winter
due to terrestrial input. Variations in particulate organic nitrogen (PON) along the
channel system were observed to be high, which might be the result of a settling
process that varies spatially through the system. This is also valid for TSS and other
particulate nutrients. 10 Dissolved reactive phosphorus (DRP) concentrations were in
the range of about 0.1-0.23

M, close to boundary concentrations for both surface
and bottom waters during spring and summer. Compared with the Redfield ratio (N:P

µ

=
16:1), DRP concentrations in the system were low; therefore, it is assumed that
phosphorus could be the limiting factor for plankton growth. However, this hypoth-
esis must be verified with bioassay tests. Excessively high silicate concentrations
(approximately 400

M) were observed in spring. Silt comprising the main soil
texture of the watershed causes high silicate concentrations; thus, silicate is not
considered a limiting nutrient for algal growth. 10 Chlorophyll a average concentra-
tions that can be used as an indicator for planktonic mass were generally lower than
4

µ

g/L.
This study compared chlorophyll a and nutrient concentrations in lagoon envi-
ronments, as shown in Table 9.5.3, wherever reliable data are available. It may be

µ

TABLE 9.5.3
Comparison of Dalyan Lagoon Nutrient and Chlorophyll a Concentrations
with Concentrations in Other Lagoons 11

NO 2 − -N
+

NH 4 + − N Chlorophyll a

(mg.m − 3 ) Lagoon NO 3 − -N ( µ M) DRP ( µ M) Si ( µ M) Reference

Celestun
(Gulf of
Mexico)

0.9-13
(4.82)

1-40 (7.82) 0.3-3.2

(0.82)

16-350
(54.4)

0.5-28.5 (5.8) Herrera-

Silveria
et al. 12

Chelem
(Gulf of
Mexico)

1-5 (1.89) 1-15 (7.31) 0.1-6 (0.41) 11-39 (36.8) 1.4-9 (3.8) Herrera-

Silveria
et al. 12

Dzilam (Gulf
of Mexico)

1-7.2
(4.07)

1-35 (2.5) 0.2-8.1

(1.45)

20-300
(163)

2-6 (2.7) Herrera-

Silveria
et al. 12

Rio Lagartos
(Gulf of
Mexico)

0.2-5 (0.7) 2-11 (8.5) 0.3-8 (1.55) 5-120 (24.7) 2-10 (4.9) Herrera-

Silveria
et al. 12

Mar Menor
(Spain)

0-0.55
(0.1)

0-4 (2) 0.5-4 (1) Gilabert

et al. 13

Dalyan
Channel
(Turkey)
Surface

0.62-22.94 0.45-6.66 0.07-0.26 41.48-512.8 1.21-4.18 Gürel 10

Bottom 0.49-28.43 0.89-6.46 0.08-0.39 17.31-448.5 0.02-7.47