Seasonal Variation of the Macrozoobenthic Community Structure at Low Salinities in a Mediterranean Lagoon (Monolimni Lagoon, Northern Aegean)

Abstract

The macrozoobenthic community structure and dynamics at low salinities (0.3 -6 psu) in a Mediterranean lagoon (Monolimni lagoon) were investigated. Samples were collected monthly from February 1998 to February 1999 at two sampling stations. Community structure was analyzed by means of uniand multivariate methods. 21 taxa were collected; the amphipod Corophium orientale and the gastropod Ventrosia maritima dominated the assemblages. Total abundance peaked (50,000 -60,000 individuals m -2 ) in mid or late autumn. Community structure showed an almost even seasonal periodicity; seasonal changes were mainly derived from the intense variation in abundance of most species and the non-occurrence of a few ones (e.g. Corophium insidiosum, Polydora ciliata) in spring and summer. Nonoccurrence, which led to a depression of the most diversity indices, was possibly the only direct impact of the extremely low salinities (~0.3 psu) on community structure. The main structuring factors of the community in the deeper outer part of the lagoon were water temperature and depth, and in the innermost part, where a Ruppia maritima meadow occurred, were water temperature and predation pressure by crabs (Carcinus aestuarii) and gobies (Knipowitchia caucasica). A temporary decline in total abundance in summer followed an increase in abundance of these predators. IntroductionCoastal brackish habitats have been the subject of extensive studies. Nevertheless, the factors determining the pattern of distribution and seasonal dynamics of the macrobenthic fauna in these habitats are not yet sufficiently known. GUELORGET and PERTHUISOT (1992) introduced the concept of "paralic ecosystem" and "confinement" and applied these concepts mainly to the study of the coastal brackish habitats of the microtidal Mediterranean Sea. The authors proposed that "confinement", which represents the turnover time of marine water, is the main factor determining the horizontal zonation of benthic assemblages in the coastal brackish ecosystems ("paralic" ecosystems); they also stated that the populations in these ecosystems remain stable despite frequent considerable environmental variations (e.g. in salinity); even more, summer dystrophic crises do not destroy the ecosystem which recovers quickly once the crisis is over.Useful information on the seasonal dynamics of the macrozoobenthic assemblages in Mediterranean coastal brackish habitats was given in some mainly recent publications (e.g. REIZOPOULOU et al., 1996;LARDICCI et al., 1997;TAGLIAPIETRA et al., 1998;KOUTSOUBAS et al., 2000); several of these studies were carried out in lagoons, which suffer from summer dystrophic crises. However, the monthly variation in macrobenthic community structure and the associated environmental factors at very low salinities in Mediterranean brackish habitats have not substantially been investigated. Monolimni lagoon, which is located in the Evros Delta (Northern Aegean), is a poikilohaline, relatively enclosed Mediterranean brackish system. Although a significant scientific...

Aquatic invertebrate's distribution in a freshwater coastal lagoon of southern Brazil in relation to water and sediment characteristics

“…In fact, studies on lentic ecosystems came to the conclusion that environmental factors such as organic matter content in sediment (Würdig et al, 1998;Cartier et al, 2010) and grain sizes (Cenzano and Würdig, 2006;Würdig et al, 2007) are considered explanatory variables for density and distribution of benthic community. In the other hand, size and habitat structure seems to play an important role on invertebrate community composition (Heino, 2000), and even water temperature and influence of macrophytes could have a key role structuring this community (Kevrekidis, 2004). p = 0.007) with negative correlation.…”

“…This community shows a different distribution in space and time, varying in accordance with water physical-chemical conditions (Pereira and De Luca, 2003), substrate type and organic matter content in sediment (Covich et al, 1999), influence of macrophytes (Kevrekidis, 2004), and local depth (Pamplin and Rocha, 2007). Because the environmental heterogeneity, these variables may differ in distinct areas of lakes, wetlands and streams, determining changes in the structure and distribution of benthos (Würdig et al, 2007).…”

Biological components of Greek lagoonal ecosystems: an overview

“…Thus, in the most enclosed lagoons, for example in Rodia of Amvrakikos, cryptophytes, such as Rhodomonas sp. and Cryptomonas sp, are the most abundant genera, while, where BAS et al, 2000b, Evros Delta: GOUVIS et al., 1997KEVREKIDIS, 1997;KEVREKIDIS, 2004a;MOGIAS 2005. Table 1 characteristics of lagoons and parameters studied.…”

“…NICOLAIDOU et al, 1983NICOLAIDOU et al, , 1985NICOLAIDOU et al, , 2006DOUNAS et al, 1998;ARVANITIDIS et al, 1999;KOUTSOUBAS et al, 2000a;GOU-VIS & KOUKOURAS, 1993;KEVREKIDIS 1997KEVREKIDIS , 2004aKEVREKIDIS et al, 2000;REIZOPOULOU & NICOLAIDOU, 2004;. The most abundant species in each lagoon are shown in Table 4.…”

“…More attention has been paid to the lagoons of Amvrakikos Bay (NICOLAIDOU & KARLOU, 1983;NICOLAIDOU et al 1985;NICOLAID-OU & KARAKIRI, 1989, REIZOPOULOU et al 1998CHRISTAKI & GOTSIS-SKRETAS, 1990;KORMAS et al 2001, REIZOPOULOU & NICOLAIDOU, 2004 while the most comprehensive study was carried out in Gialova, on the Southwest Peloponnese (ARVANITIDIS et al 1999;PETIHAKIS et al 1999;KOUTSOUBAS et al 2000a,b;McARTHUR et al 2000, TRIAN-TAFYLLOU et al 2000 (Table 2). Different aspects of the numerous eastern Macedonian and Thrace lagoons, such as phytobenthos (OR-FANIDIS et al, 2000, 2001aMALEA et al, 2003MALEA et al, , 2004, zoobenthos (KEVREKIDIS, 1997(KEVREKIDIS, , 2004aGOUVIS & KOUKOURAS, 1993, GOUVIS et al, 1997 and fishes (KOUTRAKIS & TSIKLIRAS, 2003) were also explored.…”