AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS

Aquatic Conser6: Mar. Freshw. Ecosyst. 9: 97 – 109 (1999)

Functional analysis and restoration of Mediterranean

lagunas in the Mancha Húmeda Biosphere Reser7e
(Central Spain)

MAXIMO FLORÍN* and CARLOS MONTES

Department of Ecology, Uni6ersidad Autónoma de Madrid, 28049 Madrid, Spain

ABSTRACT
1. The Mancha Húmeda Biosphere Reserve includes approximately 50 lakes, most of them
shallow and temporary (lagunas).
2. Despite their international importance, numerous impacts affect them, including pollution in
lagunas located near villages and the partial or total desiccation of most sites due to river
channelization and groundwater over-exploitation.
3. Restoration attempts over a period of years failed because they aimed to improve living
conditions for only unrepresentative indicator taxa and neglected the temporal dynamics of aquatic
systems.
4. Key recommendations are discussed for restoration, based on functional analysis: i) Restoring
and/or preserving the original hydroperiod (including drought) and the diversity of water input; ii)
protecting the structure and function of sediments, considering nutrient availability to assess water
quality; iii) categorizing the environments in terms of the dominant primary producers; iv)
complementing estimates of production by considering its fate and form of consumption; and v)
identifying key events triggering the main patterns of ecosystem organization (either episodical or
periodical, abiotic or biotic).
Copyright © 1999 John Wiley & Sons, Ltd.

KEY WORDS: lake restoration; lagunas; wetlands; conservation value

INTRODUCTION

The most important threat to Spanish lentic systems is a lack of water. When they are not deliberately
drained, channelization or groundwater exploitation deprive them of their surface or subsurface water
inputs. Spanish lentic systems also suffer from many other impacts that eventually become important at
a regional or local scale. In recent years, the oddest impact was caused by waterfowl farming activities or
‘zootechnical’ projects, which are pretentiously considered as wetland restoration by their authors
(Casado et al., 1992). These projects seek to transform aquatic ecosystems to create favourable conditions
for the breeding, nesting, feeding or resting of the highest possible numbers of waterfowl. Moreover, they
disregard the difference in environmental features between the natural and the ‘restored’ situation
(Molina, 1990). Many experts, however, demand that restoration projects have an ecosystem-based

* Correspondence to: Department of Plant Ecology and Evolutionary Biology, Utrecht University, P.O. Box 800.84, 3508 TB
Utrecht, Netherlands.

CCC 1052–7613/99/010097–13$17.50 Received 3 September 1997

Copyright © 1999 John Wiley & Sons, Ltd. Accepted 15 October 1998
98 M. FLORÍN AND C. MONTES

approach, i.e. operating within a framework which attempts to restore the various functions and general
values of aquatic ecosystems and not simply to create habitats for particular species (Montes et al., 1995).
Identifying these functions is the object of the latest generation of wetland evaluation techniques (Brinson
et al., 1994; Maltby et al., 1996).
Essentially, the procedure for the functional assessment of wetlands aims to identify abiotic and biotic
features of wetlands that are either easily measurable or available from the literature and serve to predict
the probability that a wetland site performs certain functions. Wetland functions are deduced from the
analysis of hydrogeomorphic features of wetlands and their correspondences with functional profiles of
the main wetland classes as defined by previous scientific studies. These procedures have been applied to
river marginal wetlands in Europe and a diversity of North American wetlands, but none of them is
representative of the Mediterranean regions.
The essential characteristic of Mediterranean wetlands is the particular temperature and rainfall rhythm
resulting from their opposition in seasonal timing, so that the minimum water availability coincides with
the period of maximum evaporation and demand. This general trend varies greatly, both among and
within the Mediterranean-type regions of the world (di Castri, 1991; Gonzalez Bernaldez, 1992).
Moreover, all climates of the Mediterranean type are characterized by the irregular distribution and
scarcity of rainfall through time. As a result, the principal feature of Mediterranean inland aquatic
ecosystems is the annual and inter-annual variation in water level, with a sharp and unpredictable
alternation of wet and dry periods.
Spain is the driest country in western Europe, and its climate is Mediterranean in most regions. Most
natural lentic systems in Spain are lagunas, i.e. small, shallow lakes where the length of the annual dry
period often experiences marked deviations from the average dry period of 3–4 months, particularly in
the summer (Florı́n et al., 1993). These diverse Spanish lagunas are probably the most valuable in Europe,
partly because of their spatial and temporal variability, but also for two additional reasons: 1) the rate of
loss of natural lentic habitats has been slower in Spain than in the rest of Europe due to a lower
population density and a slower rate of economic development until recent times; and 2) the privileged
location of Spain at a biogeographical crossroads for many different groups of organisms.
This paper proposes a set of guidelines for the restoration of Mediterranean wetlands based on recently
developed procedures of functional assessment. It also uses case studies to compare this approach with
that of recent waterfowl farming activities, referring to key indicators for the functioning of selected
lagunas that have a high conservation value and that suffer impacts of different types and intensities.

STUDY AREA

UNESCO’s Mancha Húmeda Biosphere Reserve includes a selection of about half of the 100 lagunas and
other wetlands of the most important wetland district in Spain. These valuable systems are located in the
natural region known as La Mancha, that covers an area of 8000 km2 in the northern part of the Upper
Guadiana river basin (Central Spain) (Figure 1). The climate is typically Mediterranean, with the lowest
average monthly rainfall occurring in summer, but with a high inter-annual variability.
There are many types of standing waters in Mancha Húmeda (Florı́n et al., 1993), from lakes to
floodplains, episodically flooded to permanent, subsaline to hypersaline and natural to artificial. Sulphate
is often the dominant anion in these waters (Florı́n et al., 1989), and this allows sulphide accumulation
in sediments under conditions of long-term waterlogging. A number of lagunas receive wastewater inputs,
resulting in the artificial attraction of large populations of waterfowl for two reasons: i) the increase in the
magnitude (intensity and duration) of flooding periods with respect to the natural hydroperiod; and ii) an
excessive increase in the provision of food resources.

Copyright © 1999 John Wiley & Sons, Ltd. Aquatic Conser6: Mar. Freshw. Ecosyst. 9: 97 – 109 (1999)
 FUNCTIONAL ANALYSIS AND RESTORATION OF MEDITERRANEAN LAGUNAS 99

The conservation status and human impacts on the lagunas and wetlands of La Mancha were described
in detail by Florı́n et al. (1993), ASHUMAN (1994) and Oliver and Florı́n (1995) (Figure 1). According
to these sources, only 12 sites are currently threatened with disappearance (Figure 1), but they account for
about half of the remaining wetland surface area (3138 ha). The eight relatively well-conserved sites
(Figure 1) account for only 295 ha, while both impacted and strongly impacted sites account for a similar
wet surface area (2051 and 1586 ha, respectively). Sites that have now disappeared account for 3419 ha.
Water-table reduction is the main threat to the Mancha Húmeda lagunas, affecting both the quantity and
the quality of their water budgets. Causes of water-table lowering include river channelization, direct
drainage of the site or its surroundings, and overall groundwater abstraction. Over-exploitation of
aquifers has become the major environmental problem for La Mancha; groundwater is the main source
for domestic water supply, but also the basis of economic development (through irrigation for agricul-
ture). However, recent restoration activities have not focused on the problem of water shortage, but on
the few eutrophic systems because of their importance for waterfowl.

Conservation value
The designation of the Mancha Húmeda as a UNESCO Biosphere Reserve in 1980 is only one among the
many international acknowledgements of the conservation value of its wetlands. Five of them are included

Figure 1. Location and conservation status of lagunas and wetlands in La Mancha. Modified from ASHUMAN (1994).

Copyright © 1999 John Wiley & Sons, Ltd. Aquatic Conser6: Mar. Freshw. Ecosyst. 9: 97 – 109 (1999)
100 M. FLORÍN AND C. MONTES

in the Ramsar List of Wetlands of International Importance. One of them, Las Tablas de Daimiel, also
represents the only Spanish National Park located in an inland wetland (Figure 1).
The high conservation value of the Mancha Húmeda lagunas in international terms is due to many
reasons. Their landscape and associated socio-economic features are unique in Western Europe (Jessen,
1946), as are their geochemical processes (de la Peña et al., 1982). The contribution of the Mancha
Húmeda wetlands to global and European biodiversity is also very important, according to standard
criteria (Table 1). However, red lists and international conventions disregard other conservation values.
This is the case for the rare aquatic herb Althenia orientalis (Zannichelliaceae), a species with a very
restricted geographical distribution that the present authors collected there in 1986, as well as for the
riparian beetle fauna, which includes the Iberian endemic Orthomus expansus (Pterostichidae) and two
species with a North African – Iberian distribution, namely Cicindela maroccana (Cicindelidae) and
Harpalus microthorax (Harpalidae) (Rueda, 1990).
The lagunas studied are also important for conservation at a habitat or community level. Six types of
habitats that are extensively represented in the Mancha Húmeda are considered to be of interest within
the European Union (Directive 92/43/EEC, adapted 97/62/EC): inland salt meadows, Mediterranean
halophilous bush formations (Sarcocornetea fruticosi ), Mediterranean salt steppes (Limonietalia), olig-
otrophic calcium-carbonate waters with a benthic vegetation of Chara spp., Mediterranean temporary
lagunas, and calcium-carbonate wetlands of Cladium mariscus. However, other valuable communities not
officially acknowledged were described by Margalef (1947) as being unique in western Europe, and
comparable to only a few other wetland districts elsewhere in the world (notably in North Africa and
Central Asia). This also applies to the microbial mats dominated by the cyanobacteria Microcoleus
chtonoplastes, the communities of submerged macrophytes dominated by Ruppia drepanensis (Potamoge-
tonaceae), the crustacean community Arctodiaptometum salini (Alonso, 1996), and the communities of
riparian carabids (Rueda, 1990).

METHODS

Guidelines for restoration were developed using the assessment process described by Brinson et al. (1994),
with particular reference to three steps in their approach: 1) hydrogeomorphological classification of
wetlands; 2) definition of relationships between hydrogeomorphological features and wetland functions;
and 3) description of the functional profiles for each wetland class. These assessment procedures have a
clear scientific rationale, as proposed by Maltby et al. (1996). However, there were also differences
between this approach and those of Brinson et al. (1994) and Maltby et al. (1996).
The first difference refers to the classification of lagunas that differ greatly from the North American
wetlands and European floodplains where the most recent procedures for functional assessment were
developed. Although in these cases the definition of hydrogeomorphological units is fundamental, it
would be ineffective in Spain where sites are smaller and discontinuous. As a result, the hydrogeomorpho-
logical classification of La Mancha lagunas used was that developed by Florı́n et al. (1993), that treats
sites as the lowest-order units. The most important predictors in this classification are: 1) the ratio of
surface area to maximum water level, which provides information about the water retention capacity of
lake basins; and 2) the proximity of main watercourses, which is related to the existence of natural, large
sources of water by association with either the fluvial water table or the areas of regional groundwater
discharge. This descriptive classification was then integrated with the functional analysis of hydroperiod
dynamics and sediment features made by Florı́n et al. (1994).
Second, the functional assessment of lagunas was complemented by a comparative analysis between
relatively well-conserved and artificially enriched lagunas. This was carried out using the following series
of descriptors: maximum water level, hydroperiod, sediment features, salinity, concentration of or-

Copyright © 1999 John Wiley & Sons, Ltd. Aquatic Conser6: Mar. Freshw. Ecosyst. 9: 97 – 109 (1999)
 FUNCTIONAL ANALYSIS AND RESTORATION OF MEDITERRANEAN LAGUNAS 101

Table 1. Some biota of international importance in the Mancha Húmeda wetlands

Group, species and (Family) Assessment source and conservation status or measurements

IUCN Red Bern Birds Habitats

Lists Convention Directive Directive

Plants
Puccinelia fasciculata (Gramineae) Vulnerable
Microcnemum coralloides (Chenopodiaceae) Vulnerable Strict
protection
Dorycnium pentaphyllum (Leguminosae) Rare Control activities
Linum muelleri (Linaceae) Strict protection
Lythrum flexuosum (Lythraceae) Vulnerable Strict Priority interest
protection
Birds
Marmaronetta angustirostris (Anatidae) Vulnerable Strict Habitat
protection conservation
Netta rufina (Anatidae) Protection
Ardea purpurea (Ardeidae) Strict Habitat
protection conservation
Botaurus stellaris (Ardeidae) Strict Habitat
protection conservation
Nycticorax nyoticorax (Ardeidae) Strict Habitat
protection conservation
Recur6irostra a6osetta (Recurvirostridae) Strict Habitat
protection conservation
Himantopus himantopus (Recurvirostridae) Strict Habitat
protection conservation
Gelochelidon nilotica (Laridae) Strict Habitat
protection conservation
Chlidonias hybrida (Laridae) Strict Habitat
protection conservation
Podiceps nigricolis (Podicipedidae) Strict
protection
Otis tarda (Otididae) Vulnerable Protection Habitat
conservation
Tetrax tetrax (Otididae) Near-threatened Protection Habitat
conservation
Other vertebrates
Emys orbicularis (Emydidae) Near-threatened Strict Strict protection
protection
Triturus marmoratus (Salamandridae) Protection Strict protection
Lutra lutra (Mustelidae) Not evaluated Strict Strict protection
protection

Assessment sources: 1996 and 1997 IUCN Lists of Threatened Animals and Plants, the Bern Convention on the Conservation of
European Wildlife and Natural Habitats, and the Directives 79/409/EEC and 92/43/EEC (adapted 97/62/EC) of the European
Communities. Species citations: Cirujano (1980), Oliver and Florı́n (1995) and unpublished data.

thophosphate, nitrate, nitrite, planktonic chlorophyll-a and dominant primary producers. These features
were selected because they were identified as being salient predictors of the functioning of the Mancha
Húmeda laguna ecosystems (Florı́n, 1994). Information on these and other descriptors was collected in the
Mancha Húmeda lagunas during three extensive limnological surveys (in the winter and spring of
1984–1985 and 1985 – 1986, and in 1989). Fortnightly to monthly monitoring was undertaken between

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102 M. FLORÍN AND C. MONTES

1991 and 1993 in a few sites of different functional types. Hydrochemical sampling and analysis were
performed using standard techniques (American Public Health Association et al., 1985). The collection of
hydrochemical data and information on biota was not possible when lagunas were dry at times of
inter-annual fluctuations and hydrological impacts.

RESULTS

Classification of lagunas
Four classes of lagunas were identified (Table 2). Three of them include natural lagunas that show good
relationships between hydrological regime and the dominant type of primary producers; the fourth
consists of lagunas receiving wastewater inputs.
The ratio of surface area to maximum water level (S:Zmax) serves to distinguish between lagunas
receiving wastewater inputs together with those characterized by microbial mats, (average S:Zmax = 1.02),
and lagunas characterized by submerged macrophytes and phytoplankton (average S:Zmax = 1.38 and
2.35, respectively). The only well-conserved laguna with microbial mats is also much shallower than
eutrophic systems (Table 2).
The distance to the nearest stream (LNS) is even shorter for phytoplankton lagunas (average LNS = 3.80
km) than for eutrophic lagunas (average LNS = 4.26 km), but the former are the most temporary systems,
while the latter are the most permanent ones. Lagunas characterized by microbial mats and submerged
macrophytes are farther from watercourses (average LNS = 4.67 and 5.36 km, respectively). An exception
is the Masegar laguna, representative of the numerous floodplain wetlands and shallow lakes associated
with rivers in Mancha Húmeda.

Relationships between hydrogeomorphological features and key functions of lagunas

Submerged macrophytes are favoured in the lagunas that have alternating large floods and dry periods.
In these lagunas, sediment anoxia and subsequent accumulation of organic matter and sulphide (toxic to
macrophytes) are limited by the occurrence of dry periods. However, flooding events that are long enough
still occur to enable macrophytes to complete their life cycles (Figure 2a). On the other hand, a succession
of frequent short flood and dry periods leads to phytoplankton- or microbenthic-dominated communities
of primary producers (Figure 2b and c). This is also the case when ephemeral flooding occurs during a
long, dry period in a macrophyte-dominated laguna.
Box-and-whisker plots of sediment features (Figure 2d) show that differences between sediment
moisture in flood and dry periods of some lagunas (Figure 2a and b) are highly significant; however, this
is not the case in the laguna shown in Figure 2c. The stability of sediment waterlogging in this laguna
allows a well structured microphytobenthic community to resist the superficial desiccation of the laguna.

Description of the functional profiles for four classes of lagunas

Although the previous descriptions do not include all types of the Mancha Húmeda lagunas, they provide
the basis for classifying a few functional profiles in terms of the descriptors previously selected (Table 2).
Four main groups of lagunas may be distinguished, three of them being relatively well-conserved. The
fourth type consists of eutrophic systems that receive wastewater inputs; all of these, with the exception
of the Laguna Larga, are Ramsar sites and targets for restoration. It is noteworthy that eutrophic lagunas
have a higher NO2− concentration, together with a higher water level and lower salinity. Nitrate
concentrations are not markedly different between eutrophic and unenriched lagunas, but the highest
concentrations of PO34 − and consistently high concentrations of chlorophyll-a were recorded in the

Copyright © 1999 John Wiley & Sons, Ltd. Aquatic Conser6: Mar. Freshw. Ecosyst. 9: 97 – 109 (1999)
Copyright © 1999 John Wiley & Sons, Ltd.
Table 2. Range of key descriptors of different functional types of the Mancha Húmeda lagunas

Laguna LNS S:Zmax Zmax Salinity PO3−

4 NO−3 NO−2 Chlorophyll-a Hydroperiod, sediment type and
(km) (cm) (g L−1) (mg L−1) (mg L−1) (mg L−1) (mg L−1) dominant primary producers

FUNCTIONAL ANALYSIS AND RESTORATION OF MEDITERRANEAN LAGUNAS

Masegar — — 59 3–15 0.01–0.04 0.18–1.4 0.01 0.84–2.7 Inter-annual, high-magnitude flood and
Altillo II 4.5 1.2 15 4 0.00 4.7 0.06 2.29 dry periods (Masegar is dammed).
Albardiosa 2.9 3.2 80 5–147 0.00–1.2 0.00–0.39 0.00–0.09 0.56–57 Sandy sediments. Ruppia drepanensis,
Pajares 7.7 1.0 7 11–39 0.24–0.89 0.28–1.2 0.11–0.13 1.2–4.5 except in Masegar and Dehesilla, with
Dehesilla 4.2 0.7 40 27–45 2.4 0.31–3.4 0.21 4.2–10 Chara spp. and Lamprothamnium
Salobral 3.7 0.3 30 30–314 0.02–0.41 0.05–0.43 — 1.8–80 papulosum, respectively. Masegar also
Sánchez-Gómez 4.5 1.6 40 35–95 3 1.7 0.34 9.4 with Cladium mariscus and Phragmites
Altillo 1 5.1 1.4 4 45 0.24 0.24 0.13 9.7 australis, Altillo I also with Althenia
Salicor 10 1.7 63 66–440 0.00–5.0 0.00–4.6 0.00–0.69 0.46–131 orientalis. Eventually, macrophytes are
replaced by phytoplankton during short
flooding periods.
Alcahozo 4.7 1.0 18 68–460 0.04–1.8 0.01–8.7 0.00–0.21 0.92–19 Irregular alternation of short periods
of flooding and desiccation. Sandy
sediments rich in organic matter.
Microbial mats characterized by
Aquatic Conser6: Mar. Freshw. Ecosyst. 9: 97 – 109 (1999)

Microcoleus chtonoplastes.
Mermejuela 5.1 0.2 14 39–427 0.00–2.1 6.7–9.0 0.00–0.37 7.2–18 Irregular alternation of short periods
Tirez 4.0 2.4 20 163–231 4.4–19 0.62–1.4 0.08–0.49 11 of flooding and desiccation. Clay
Grande de Quero 4.0 1.9 8 217 7.9 — 0.53 3.7 sediments. Only phytoplankton is
Peña Hueca 2.1 5.0 20 86–460 0.00–8.4 0.00–1.3 0.00–0.41 2.5–228 present, typically Dunaliella spp.
El Pueblo 6.9 0.8 50 6–14 0.02 0.36 0.21 1.7–14 Main water inputs are relatively
Manjavacas 5.2 3.6 60 11–12 0.02–31 0.00–0.14 0.26–0.61 58–21 constant flows of wastewater
Camino Villafranca 4.6 4.6 40 18–29 — — — 72 throughout the year. Organic sediments
Larga Villacañas 2.4 2.1 80 46 5.2 — — 99 up to 40 cm deep, accumulated
Yeguas 2.2 3.2 11 41–119 35.7 1.3 0.77 85 during years. Hardly any macrophytes,
phytoplankton typical of wastewater.

LNS, distance to the nearest stream; S:Zmax, ratio between the surface area divided by the maximum water level; Zmax, maximum water level.

103
104 M. FLORÍN AND C. MONTES

eutrophic lagunas. There does not appear to be any particular difference between the Laguna Larga and
the other eutrophic but restored lagunas in terms of PO34 − and chlorophyll-a concentrations.
The functional groups of non-eutrophic lagunas are characterized by the complex interaction of several
factors, adding to the other differences in hydrology, sediment features, and dominant primary producers
(Table 2). Alcahozo, the unique laguna dominated by the microphytobenthos, is very shallow and has
relatively low concentrations both of nutrients and chlorophyll-a, and intermediate to high salinity.
Lagunas dominated by macrophytes experience wide fluctuations in the concentration of phytoplanktonic
chlorophyll-a and salinity, and have relatively high water levels. Finally, phytoplankton-dominated
habitats have low water levels, high to very high salinities, and wide fluctuations in the concentration of
chlorophyll-a.

Figure 2. Variation of hydrological descriptors between December 1990 and March 1993 in three lagunas with different dominant
types of primary producer: a) Albardiosa, characterized by submerged macrophytes; b) Peña Hueca, characterized by phytoplank-
ton; and c) Alcahozo, characterized by microbenthos; d) shows their sediment features both in dry and flooded periods (number of
sampling visits, 22; three replicates per site and per sampling visit). These lagunas represent three of the functional profiles described
in Table 2 (i.e. the non-eutrophic lagunas).

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 FUNCTIONAL ANALYSIS AND RESTORATION OF MEDITERRANEAN LAGUNAS 105

DISCUSSION

Implications of functional analysis for restoration

The Mancha Húmeda lagunas are small, shallow systems with a strongly fluctuating water level (Figure
1). This explains the wide variability in the concentration of chlorophyll-a and (in some cases) nutrients
(Table 2). In effect, the alternation of flooding and desiccation exposes ecological communities to an
intense recycling of nutrients and organic matter.
Within the overall definition of Mediterranean lagunas, there is an important variability that results in
the existence of quite different trophic patterns, but also high conservation values (Table 1). Waterfowl
and other vertebrates — indeed animals in general and even higher plants—are absent from some of the
most unusual functional profiles that were found among the Mancha Húmeda lagunas. Therefore, site
restoration should be planned more on the basis of constant features throughout the different functional
types. The dominant group of primary producer is the most appropriate for this purpose, since each one
builds specific trophic patterns that should be assessed at the same level of priority.
These general principles can best be applied to restoration by using well-defined protocols, particularly
with reference to the controlling variables that define key relationships between hydrogeomorphological
classes and functions of lagunas, e.g. the water retention capacity of lakes and the occurrence and quality
of water inputs. These were assessed in Mancha Húmeda using lake descriptors such as the ratio of
surface area divided by the maximum water level, the proximity of main watercourses and the sediment
water content. Their integrated analysis seems to serve well to distinguish between the functional profiles
of natural lagunas described in Table 2, but also between natural and eutrophic systems. Therefore, these
variables may be used as predictors of the functional integrity of lagunas. Florı́n et al. (1993) consistently
found abnormal relationships between the values of the two former descriptors and the expected
hydrological regime for impacted sites, both when the sites were drier and wetter than predicted.
Once laguna types and restoration priorities are fixed, functional profiles, such as those described in
Table 2, may serve to identify ecological targets for restoration. These profiles show the specific
correspondences between ecological functions and ranges of the predictors mentioned above, and also
show links with the timing, frequency, duration, intensity and long-term pattern of hydrological
fluctuations (Figure 2). These profiles should not be taken as being definitive for two reasons: i) many
episodically flooded and strongly impacted lagunas on which information is still lacking are not likely to
be represented; and ii) the functional predictors proposed should first be calibrated against independent
sets of representative reference sites for each profile (Brinson et al., 1994). Filling these gaps in knowledge
is a question of time, rather than an unsuitability of the approach proposed.
The application of the above guidelines may be extended beyond the scope of the Mancha Húmeda
district. The broad validity of the approach is supported by the theoretical formulations of Margalef
(1987) concerning the connections between hydrogeomorphological features and the functions of primary
producers in systems characterized by a fluctuating water-level. These are typical of Mediterranean and
semi-arid regions, where water shortage is common (Williams and Aladin, 1991; Williams, 1993a).
Frequently, these wetlands or lakes are also threatened by hydrological impacts, but they still maintain
their high conservation value (Williams, 1993b).

Review of the Mancha Húmeda restoration projects in the light of functional analysis criteria
‘Restoration’ projects developed thus far in the study area have not been based on a reliable classification
and the subsequent setting of priorities for action. The most outstanding result of this is the absolute
neglect, for restoration purposes, of the most threatened lagunas of Mancha Húmeda, i.e. those of its
northern part (Figure 1) (Florı́n et al., 1993). Any criteria of international importance (Table 1) are also
disregarded. Four of the most conspicuous projects described by Molina (1990) involve Ramsar sites

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106 M. FLORÍN AND C. MONTES

which receive wastewater inputs. However, there is no evidence of action aimed at protecting or enhancing
Ramsar values. Special attention will be paid here to these projects, because they are a responsibility of
the regional environmental authority of Mancha Húmeda.
In all cases, the projects developed tend to increase water levels and to smooth the hydrological
fluctuations that are natural in Mediterranean wetlands. Molina (1990) absurdly describes the mainte-
nance of water during summer as proof of success of a 12-hm3 trans-catchment import of water to the
National Park of Daimiel in 1988. This sort of attitude is sometimes even more harmful, for example
when the local authorities decided to restore the Salobral laguna. In 1992, solid urban waste discharges
were accumulated in its margins to deepen the natural basin, and an encircling channel was excavated to
direct subsurface run-off towards the laguna. Two other lagunas have been artificially filled with water
from wells for bathing purposes.
In some cases, restoration action had a regional impact. Hydrological restoration of the Daimiel
National Park (Sánchez, 1995) included the ‘cleaning’ (channelization) of the Cigüela river upstream of
the Daimiel wetland, just where the river crosses one of the western wetland sectors (Figure 1). This
included ditching, deepening and straightening 25–80 km of the river course. It meant breaking the
hydrological exchange between the river and its marginal wetlands, and also between the river and the
regional water cycle. The action was aimed at ensuring that all river discharge reached the Daimiel
wetland, instead of being partially lost in the Cigüela floodplains. Channelization as a restoration
measure? Not even for the Daimiel wetland, because after deepening the river channel, its bed coincided
with a layer of more porous substrata, resulting in a higher infiltration of water along its course.
In general, restoration activities include the excavation of lagunas and the transport of sediments from
one to another side of their basins in order to construct islands, ponds and beaches that favour the
presence of waterfowl (Molina, 1990). This may be acceptable in artificial ecosystems, such as the
abundant gravel pits of the neighbouring Tagus catchment (Escribano et al., 1995). Nevertheless, it is the
converse of true restoration if carried out in natural lakes, especially if they have conservation values such
as those shown in Table 1. Sediment functions are seriously threatened by its removal, dramatically
affecting the water retention capacity of laguna basins. Biogeochemical processes are disturbed, sediment
organic matter is remobilized and eutrophication may be enhanced. Microbial mat communities depend
upon the steadying influence of sediments against hydrological fluctuations (Figure 2c and d). Sediments
shelter spores, seeds, eggs or drought-resistant forms of a number of species and communities of high
conservation value (e.g. Characeae algae, the aquatic herbs Althenia and Ruppia, and zooplanktonic forms
of the Arctodiaptometum community). Damaging the sediment structure has impacts at different time
scales: i) in the short-term on the food webs involving the above processes and biota; and ii) in the
longer-term on related succession paths and on the function of sediments as biodiversity reservoirs against
hydrological fluctuations.
The restoration projects described by Molina (1990) also failed to take into account water quality. The
fact that the restored sites are polluted seems to be incidental, because no action was taken to stop
wastewater inflows. In the Daimiel National Park, the dilution of indirect wastewater inputs with
supplementary water inputs has been mentioned as a proof of success of the plan for its hydrological
regeneration because ‘undetectable pollution indexes’ were reached (Molina, 1990). It is not even true that
these projects serve to favour waterfowl populations. Recycling of organic matter is lower in lagunas that
are managed to maintain a constant water level. Thus, organic matter tends to accumulate and, what is
more, these systems tend towards dystrophy if they also receive wastewater inputs. This is probably an
abundant source of food for numerous waterfowl, mainly Anas platyrhyncos and Fulica atra. Under these
conditions, pathogenic bacteria are also likely to be favoured, according to the frequent summer
epidemics (mainly botulism) that affect waterfowl in the restored sites (Molina, 1990).
Finally, consideration of living organisms other than waterfowl are generally absent from the restora-
tion projects developed in Mancha Húmeda. When vegetation is considered, it is because ‘flora may

Copyright © 1999 John Wiley & Sons, Ltd. Aquatic Conser6: Mar. Freshw. Ecosyst. 9: 97 – 109 (1999)
 FUNCTIONAL ANALYSIS AND RESTORATION OF MEDITERRANEAN LAGUNAS 107

satisfy the ecological needs of aquatic fauna’ (Molina, 1990, p. 335). This author states that waterfowl
habitat may be improved by delaying ecological succession by: i) the partial clearing of dense vegetation;
and ii) controlled burning of vegetation in the wetland bed and its margins. These practices are
traditionally used in the wetland hunting sites of the region.

CONCLUDING REMARKS

Recent approaches to the functional assessment of wetlands have been successfully applied here to provide
guidelines for restoring Mediterranean lagunas. It is proposed that different models be used to assess the
functions of sites dominated by different groups of primary producers (microbenthos, plankton and
macrophytes). Functional profiles are defined using predictors that can be extensively measured in a
regional context. Major controlling variables for all functional profiles are the water retention capacity of
lake basins, the occurrence and quality of large water sources, the temporal features of hydroperiod and
the steadying influence of sediments. In the same way that natural profiles may be used to define
restoration targets, their predictors can serve as a restoration tool.
The assessment was carried out using information that is easy to measure or available from the
literature. The only requisite was to focus the analysis on the functioning of laguna ecosystems, rather
than on isolated species or communities. This was the failure of previous restoration experiences in
Mancha Húmeda, resulting in lessening or threatening various functions of the affected sites (e.g.
biodiversity maintenance, food-web and habitat support, both hydrological and biogeochemical).
If special care is taken with the inclusion in the classification of the relevant types at the relevant scale,
and in defining the relationships between the hydrogeomorphological features that defined these types and
the functions of lagunas, then the setting of restoration targets will become much more objective than the
zootechnical-based activities carried out until now. No controversy between aquatic ecologists and
wildfowl biologists is intended. If the natural functions of a diversity of lagunas are restored, birds will
certainly be conserved at the proper sites, but so also will remaining conservation values that justify the
international acknowledgement of the Mancha Húmeda wetlands.
Information gaps should be identified and filled in the short- or long-term. Meanwhile, using available
information from functional assessment procedures is an open approach that has the potential to be
improved with time, and it avoids the disadvantage of taking decisions based on subjective criteria.
Further research is needed on the functioning of the less-saline wetlands and lagunas, perhaps less
interesting from the scientific point of view, but much more threatened. This includes the investigation of
the relationships between hydrogeomorphological features of lagunas and new functions not identified
before, and also the definition of the corresponding functional profiles. Clarifying the trophic and
geographical relationships between waterfowl and primary producers will surely provide a number of
additional guidelines for restoring Mediterranean wetlands. Last, but not least, it is desirable that
zootechnical engineering creates wetlands in areas where they have been lost completely, rather than
interfering with the functioning of systems which can be restored to their former states (P. Evans, Durham
University, personal communication).

ACKNOWLEDGEMENTS
Very special thanks to Professor P. Evans (Durham University) for his corrections and valuable philosophical inputs.
Corrections by Dr C. Frid (Dove Marine Laboratory) resulted in a significant improvement to the English. This work
was possible because of the financial support from the Spanish Ministry of Education and Culture (grant
PF96-0050048879) and the Commission for Science and Technology (projects NAT90-0721-C02-01 and AMB94-
0827).

Copyright © 1999 John Wiley & Sons, Ltd. Aquatic Conser6: Mar. Freshw. Ecosyst. 9: 97 – 109 (1999)
108 M. FLORÍN AND C. MONTES

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