Turkish Journal of Zoology Turk J Zool (2015) 39: 888-905 http://journals.tubitak.gov.tr/zoology/ © TÜBİTAK Research Article doi:10.3906/zoo-1407-8 Broad-scale ecological distribution of dominant macrozoobenthic taxa of the northern Cilician shelf, eastern Mediterranean Sea: crustaceans* Erhan MUTLU** Fisheries Faculty, Akdeniz University, Antalya, Turkey Received: 03.07.2014 Accepted/Published Online: 03.02.2015 Printed: 30.09.2015 Abstract: The distribution of crustaceans in 3 transects (İskenderun, Mersin, and Anamur bays, including depths of 10, 25, 50, 75, 100, and 200 m) located within Turkish coastal borders of the Cilician shelf was studied between 2005 and 2007 to show the association with habitat types, eutrophication level, and depth-dependent environmental parameters in representative months of each season (winter, spring, summer, and autumn). A total of 153 crustacean taxa were found. Of the specimens identified at species level, 93 species were distributed in the Mediterranean Sea and Atlantic Ocean, 12 in the Indian Ocean and the Red Sea, and 4 in the cosmopolitan waters of the oceans. Three crustacean assemblages were distinguished according to the habitat types and eutrophication levels of the study sites: 1) the crustacean community of the eutrophic regions was dominated by decapods and characterized by high biomass, low faunistic characters, and high nutrient concentrations; 2) the assemblage of the bottom, vegetated with a meadow, exhibited well-diversified assemblages mainly composed of amphipod species with high faunistic characters, low biomass, and dissolved oxygen content; and 3) the assemblage of the nonvegetated undisturbed soft bottom was associated with the sedimentary parameters along the bottom depths (10–25 m, 50–100 m, and 150–200 m). Key words: Zoobenthos, Crustacea, Cilician shelf, Turkey 1. Introduction Coastal ecosystems of the North Levantine The Cilician Basin contains a unique wide continent shelf, Basin have undergone permanent changes due to excluding the Nile Delta in the eastern Mediterranean increasing anthropogenic inputs, resulting in elevated Sea, which is ultra-oligotrophic with primary productivity eutrophication, mainly in İskenderun and Mersin bays. (Krom et al., 2004). The determinant that makes the Domestic industrial and agricultural residues resulting Cilician Basin important is the occurrence of riparian from excessive nutrient inputs cause intense outbursts of rivers discharging into the region (Figure 1). Nevertheless, monospecific phytoplankton (Uysal et al., 2003), which the Nile River influences the Cilician Basin via rim cause a negative impact on water quality, evident in the currents of the eastern Mediterranean (Uysal et al., 2008). process of decomposition, reduction of the concentration The Cilician shelf has not been well documented in of dissolved oxygen, and light penetration. In the 1970s, terms of the biophysicochemical properties of its pelagic the intensive destruction of algal communities in the waters, although basin-wise the oceanography of the Mersin port and coastal areas was observed for a few eastern Mediterranean, including the Cilician Basin, has years. The inner Gulf of İskenderun, the Mersin inner been well studied. Geological characteristics of the shelf bay, and the western coastal area were rich in terms of were published by Ergin (1996) and Ediger et al. (1997), population density of phytoplankton. In these areas, the and a few national projects have focused recently on the current regime is generally from east to west, and inputs oceanography of the shelf, including the present study area of the Seyhan and Ceyhan rivers contribute to the form (POEM, 1986a, 1986b; Salihoğlu and Mutlu, 2000; Uysal of the eutrophic region. The port of Mersin has a sewage- et al., 2008; SINHA, 2010). The present study was carried water treatment system, which is one of the factors causing out as a subtask of the project context (Uysal et al., 2008). eutrophication of the region. Chl-a concentration in the * This study was carried out at the Institute of Marine Sciences, Middle East Technical University, Erdemli, Mersin, Turkey, where the author then worked. ** Correspondence: [email protected] 888 MUTLU / Turk J Zool 37 I2I1 M0 I3 M1 M2M3 M4 M5 I4 36.5 M6 İskenderun Bay Mersn Bay I5 I6 M7 I7 A2A1A3 A4A5A7A6 Anamur Bay 36 33 33.5 34 34.5 35 35.5 36 36.5 I2I1 A1 M0 I3 A2 M1 M2M3 A3 M4 A4 M5 I4 M6 A5 A7A6 I5 I6 M7 I7 Figure 1. Study area and Turkish part of the Cilician Basin (transects: M: Mersin, I: İskenderun, A: Anamur) and location of the sampling stations (depth code: 1: 10 m, 2: 25 m, 3: 50 m, 4: 75 m, 5: 100 m, 6: 150 m, and 7: 200 m) visited in November 2005, March 2006, July 2006, and January 2007. inner Gulf of Mersin, İskenderun, and the Göksu and by induced variables (chemicals, nutrients, and energy Seyhan rivers is higher than in other open waters. Warmer consumption), direct variables (grain size of sediment and surface waters from the west to the east have been getting temperature), and indirect variables (depth and latitude) colder, and deep, cold waters with rich nutritive salts are (Meynard and Quinn, 2007). Substrates and habitat, such pumped up to the surface waters towards the end of the as hard and soft bottoms and vegetative marine beds, play continental shelf waters of the Gulf of Mersin. Therefore, a an important role in biodiversity patterns (Williams and high concentration of chl-a occurs. The Gulf of İskenderun Bax, 2001; Beaman et al., 2005; Beaman and Harris, 2007). is higher in nutrients than Cape Akıncı off the Gulf of There is richer biodiversity in seagrass beds than in sandy İskenderun (Uysal et al., 2008). and muddy soft bottoms, and this diversity drives the A current system that could derive variable increase of biodiversity in adjacent regions. Nevertheless, measurement values of the environmental parameters, and seagrasses that host many epiphytes along their leaves therefore change the response of the benthic community, are not a favored food source for grazing taxa (Jenkins prevails toward the west along the Turkish area of the and Wheatley, 1998; Fry, 2006). Other sources that have Cilician Basin. In İskenderun Bay, station I7 is located on altered the biodiversity and richness are eutrophication the westward rim current, whereas the rest of the stations and nutrient enrichment, followed by high primary are located in a constant water system. The stations of productivity, which reduce the species richness and Mersin Bay are located at a meso-scaled cyclonic eddy. increase the evenness of the benthos in near-shore waters The stations at Cape Anamur are located in a very constant (Snelgrove, 2001; Hillebrand et al., 2007), in contrast to current system, as all stations are very close to the shore oligotrophic waters (Poore et al., 2008). After detritus (Uysal et al., 2008). forms as a consequence of primary production and waste A variety of environmental gradients affect the of zooplankton, the deposited particulate organic carbon biodiversity pattern of benthic organisms. The effects (POC) drives the biodiversity of the benthos (Seiter et of those gradients occur in different ways, resourced al., 2005). One of POC’s fluxes, total organic carbon 889 MUTLU / Turk J Zool (TOC), is a powerful variable explaining the community 2. Materials and methods structure within an ecological framework of tolerant and The area of the basin is nourished by the Seyhan, Ceyhan, intolerant species to pollution and opportunistic species and Göksu rivers. Mersin and İskenderun bays are (Gogina et al., 2010). TOC alone sometimes does not show considered to having nonvegetated bottoms, while the good correlation with faunistic characters of the benthos bottoms of the shallow stations (A1 and A2) off Cape because of the effect of bacterial degradation in sediments Anamur are covered by Posidonia beds. The inner part (I1 overstocked with TOC (Danovaro et al., 1995; Cartes et and I2) of the Gulf of İskenderun is generally disturbed by al., 2002). its own nutritional dynamics derived from enclosed eddies Benthic crustaceans can potentially be consumed by and anthropogenic activities. The benthic samples of the humans and other organisms inhabiting the sea, and they study for the Levantine Sea were collected at 7 separate are also tools for monitoring the ecological status and water depths (10, 25, 50, 75, 100, 150, and 200 m) on 3 transects, quality in bioassay experiments (Cockroft et al., 1988). each located in İskenderun, Mersin, and Anamur bays of Particular to the Levantine Sea, alien benthic crustaceans the Cilician continental shelf in November 2005, March and establishing and succeeding in the sea replace or fill the July 2006, and January 2007 by R/V Bilim-2 (Figure 1). Even gaps in ecological niches left by native benthic crustacean though the continuity of the subsequent sampling seasons species. Prior to the 2000s, the last decadal benthic under the trended atmospheric and sea condition events ecological and distributional research of the eastern could have been optimized for a better understanding of Mediterranean Sea was performed only for the waters of the crustacean community, the samplings were performed Greece and Israel (Galil and Lewinsohn, 1981; Karakassis well enough for the ecological parameters to explain the and Eleftheriou, 1997; Tom and Galil, 1991; Papazacharias crustacean community structure. A Van Veen grab (0.10 et al., 1998; Conides et al., 1999; Tselepides et al., 2000). m2 surface area) was used to take one sample from each Thereafter, alien species, new records, and new species station. However, some stations (I5 in November, I5–I7 in of crustaceans were studied in the Turkish waters of the March, and the last few deep stations off Anamur) could Levantine Sea (Çinar et al., 2006; Özcan et al., 2006; Ateş not be sampled due to the bad weather and close depth et al., 2007a; Bakır et al., 2007; Yokes et al., 2007; Çinar et contours of the bay in the March–January sampling only al., 2008; Doğan et al., 2008; Ateş et al., 2009; Çinar et al., (Figure 1).