Homa Lagoon Research Articles

Assessment of origin and abundance of beach litter in Homa Lagoon coast, West Mediterranean Sea of Turkey

The pollution of beach litter was seasonally evaluated in a selected beach in the West Mediterranean Region of Turkey between December 2019 and September 2020. Beach litter survey was carried out seasonally according to ‘Guidance on Monitoring of Marine Litter in European Seas’ published by European Marine Strategy Framework Directive Technical Subgroup on Marine Litter. During the study, a total of 2.324 items and 105.44 kg were collected. The average litter density was 581.0 ± 60.04 items/m2 and 26.36 ± 0.85 g/m2. The results indicated that the most common type of litter were plastic/polystyrene (35%), unidentifiable (18%) followed by cloth/textile (16%). Litter density showed significant seasonal differences with the highest in summer (P < 0.05). Homa beach was classified as “dirty” according to Clean Coast Index. It was observed that the litter in the region averagely consisted of mixed packaging litter (24.25%), fisheries related litter (19%) and unclassified litter (15.25%) items. Our results show that the coast of Homa Lagoon exposed to a significant amount of marine litter pollution originated from land-based sources. This study provides further evidence that there is a significant litter pollution in the West Mediterranean Sea of Turkey and that the main component are plastics, which pose a great treat to the Mediterranean Sea environments.

Effect of Different Media on Short Term Storage of Leaping Mullet (Liza saliens (Risso, 1810)) Sperm

The present study aimed to evaluate the activation characteristics of the leaping mullet spermatozoa and diluted with four different media (D1, D2, D3, D4) for 250 h at 4±2°C. The semen was collected from nine wild fish in Homa Lagoon, İzmir, Turkey in July, during reproductive season. In each trial (n = 9), semen samples were collected and mixed to reduce sperm quality variation to obtain the required gametes for the experiment. The semen was activated with natural seawater (salinity of 34, pH 7.9 and 4±2°C) to determine: motility time, motility rate and viability of sperm. Dilution with inactivation media 1:3 increased motility time of diluted semen than control group. At the end of the experiment, no significant difference was found for the duration of survival in the D2 and D4 groups. The highest survival rate was found in D2 group.

Homa Dalyanı’nda sülüneslerde (Solen marginatus) Hg, Cd, Pb ve Cr birikimlerinin incelenmesi

In this study; the accumulation of Hg, Cd, Pb, and Cr were investigated seasonally in razor clams (Solen marginatus) from the Homa Lagoon. The highest heavy metal concentrations were found in summer which is spawning period. When detected Hg, Cd and Pb levels were compared with provisional tolerable weekly intake (PTWI), Turkish Food Codex and European Regulations values, no potential health risk was found. However, heavy metal pollution in razor clam from the Homa Lagoon should be monitored due to excessive Cr concentrations in respect to PTWI value.

Seasonal variations of multi-biomarker responses to metals and pesticides pollution in M. galloprovincialis and T. decussatus from Homa Lagoon, Eastern Aegean Sea

Biomarkers (CAT, SOD, GPx, and AChE) were investigated in hepatopancreas and soft tissues of mussels (Mytilus galloprovincialis) and clams (Tapes decussatus) in response to metal and pesticide pollutions in Homa Lagoon. Mussel and clam samples were seasonally collected in January, May, August and November 2015. According to the results, higher metal concentrations determined in the soft tissues of both species in January. Hepatopancreas was found to accumulate higher levels of metals than soft tissue. Metal deposition potential in clams were higher than mussels. Pesticide levels were below detection limits in clams. In mussels, only 4,4′-DDE was detected in soft tissues and hepatopancreas in November. Highest AChE, CAT, SOD and GPx activities in mussels were determined in January. On the other hand, maximum AChE and CAT activities in clams were found in November. Seasonal variations of metals and biomarker levels might be related to species-specific physiology and environmental conditions.

Consecutive repetition of lordosis-kyphosis in silverside Atherina boyeri Risso, 1810 collected from a wild population in Homa Lagoon, Izmir, Turkey

Abstract The incidence of severe consecutive repetition of lordosis-kyphosis involving three flexions was reported in a specimen of the atherinid fish Atherina boyeri Risso. The values for the angles lay between the lines passing through the sides of the vertebral column and enclosing the curvatures, and the depth of the curvatures of the angles was obtained. Also, the ratio of the vertebral column to the fish total length of deformed and normal specimens of this species was calculated. Possible causes for these anomalies are discussed.

Assessment of trace metal concentrations and human health risk in clam (Tapes decussatus) and mussel (Mytilus galloprovincialis) from the Homa Lagoon (Eastern Aegean Sea).

Seasonal variations of trace metal concentrations (Hg, Cd, Pb, Cr, Zn, and Cu) were investigated in the hepatopancreas and soft tissues (remaining parts of bivalves such as gill, mantle, foot, and muscle) of Tapes decussatus and Mytilus galloprovincialis from the Homa Lagoon. The highest metal concentrations were recorded frequently in February and July in M. galloprovincialis and T. decussatus, respectively. Trace metal levels (except Zn) in the hepatopancreas were higher than those in soft tissue for both bivalves. The results showed that the mean concentrations of Hg, Cd, and Zn for M. galloprovincialis were higher compared to T. decussatus in both tissues. The metal concentrations in both bivalves from the Homa Lagoon were generally below the values of provisional tolerable weekly intake (PTWI) estimates, in terms of human health risk. According to hazard quotient (HQ), Cr values for both species and Cd values for only M. galloprovincialis were found greater than one. Also, total hazard index (THI) values were greater than one in both bivalves, having a potential risk for consumers.

Homa Dalyan'ında (İzmir Körfezi) dağılım gösteren Mytilus galloprovincialis ve Tapes decussatus (Bivalvia) türlerinde ağır metal birikimlerinin incelenmesi

Homa Dalyan'ında (İzmir Körfezi) dağılım gösteren Mytilus galloprovincialis ve Tapes decussatus (Bivalvia) türlerinde ağır metal birikimlerinin incelenmesi

Homa Dalyan'ında (İzmir Körfezi) dağılım gösteren Mytilus galloprovincialis ve Tapes decussatus (Bivalvia) türlerinde ağır metal birikimlerinin incelenmesi

Homa Dalyan'ında (İzmir Körfezi) dağılım gösteren Mytilus galloprovincialis ve Tapes decussatus (Bivalvia) türlerinde ağır metal birikimlerinin incelenmesi

Seasonal variation in reproductive activity and biochemical composition of flat oyster (&lt;em&gt;Ostrea edulis&lt;/em&gt;) in the Homa Lagoon, Izmir Bay, Turkey

The reproductive cycle of the flat oyster, Ostrea edulis Linnaeus, 1758, in Homa Lagoon, Izmir Bay, Turkey was examined from August 2008 to July 2009. Gonad samples were analysed histologically in order to determine the sex ratio and gonad development stage. Overall, the sex ratio was recorded as 2.2% female, 42.6% male, 37% hermaphrodite and 17.9% inactive. Glycogen content showed considerable variations between August and February, but decreased gradually thereafter. However, glycogen did not directly affect the reproductive cycle. Total lipid content was positively correlated with temperature and inversely correlated with salinity. In addition, this parameter was influenced by the reproductive activity, which is correlated with the fluctuation of the condition index and gonad index (P < 0.05). However, the relationship between the protein index and the gonad index was negative (P < 0.05). The results of this study showed that protein was the major energy resource. The condition index varied between 2.69±0.91 (February) and 12.29±1.45 (April) during the year. With respect to meat yield, oyster quality changed from “fine” to “special”, except in December and February.

Length–weight relations for 29 fish species from Homa Lagoon, Aegean Sea, Turkey

In the course of the presently reported study, covering the Homa Lagoon, Izmir Bay, Turkey, we collected a total of 2690 fish specimens belonging to 15 families and representing 29 species: Anguilla anguilla (Linnaeus, 1758); Atherina hepsetus Linnaeus, 1758; Atherina boyeri Risso, 1810; Belone belone (Linnaeus, 1761); Blennius ocellaris Linnaeus, 1758; Sardina pilchardus (Walbaum, 1792); Aphanius fasciatus (Valenciennes, 1821); Engraulis encrasicolus (Linnaeus, 1758); Gobius niger Linnaeus, 1758; Pomatoschistus marmoratus (Risso, 1810); Pomatoschistus minutus (Pallas, 1770); Zosterisessor ophiocephalus (Pallas, 1814); Dicentrarchus labrax (Linnaeus, 1758); Chelon labrasus (Risso, 1827); Liza aurata (Risso, 1810); Liza ramada (Risso, 1827); Liza saliens (Risso, 1810); Mugil cephalus Linnaeus, 1758; Mullus barbatus Linnaeus, 1758; Mullus surmuletus Linnaeus, 1758; Syngnathus acus Linnaeus, 1758; Syngnathus typhle Linnaeus, 1758; Diplodus annularis (Linnaeus, 1758); Diplodus vulgaris (Geoffroy Saint-Hilaire, 1817); Lithognathus mormyrus (Linnaeus, 1758); Sarpa salpa (Linnaeus, 1758); Sparus aurata Linnaeus, 1758; Platichthys flesus (Linnaeus, 1758); Solea solea (Linnaeus, 1758). The fish were weighed, and measured and their length&#8211;weight relations were determined. Samples were collected during 2009&#8211;2010 using four different types of fishing gear (beach seine, fyke nets, barrier trap, and trammel nets; mesh size: 25, 28, and 30 mm) that allowed both adult and juvenile specimens to be captured. Significant length&#8211;weight relations were found for all species. The exponent b varied between 2.753 for Pomatoschistus marmoratus and 3.650 for Aphanius fasciatus (mean value = 3.115). The length&#8211;weight parameters of the same species may be different in the population because of feeding, reproduction activities and fishing etc. Therefore, we need to know length&#8211;weight relations of fish, which are captured in a given place in a certain period of time. Length&#8211;weight relations for 5 out of the 29 fish species are presented for the first time from Homa Lagoon in the Turkish Aegean Sea.

Homa Lagün’ünde Mevsimsel Nutrient Zenginleştirme Denemesi (İzmir Körfezi, Ege Denizi )

In order to determine the effects of nutrient (P, Si, NH4, NO3) enrichment on the growth of phytoplankton in Homa Lagoon (İzmir Bay, Aegean Sea), experiments of enrichment with discontinuous cultures have been executed seasonally in 2007. In our study, the elements limiting the growth of phytoplankton were NO3, P and Si in spring season, N and P in summer season, and NH4 in autumn and winter seasons. So, it has been determined that the addition of nitrogen (N) and phosphor (P) has led significant change in biomass and growth of phytoplankton. It has also been observed that diatom and dinoflagellate species have grown under various concentrations of, especially, Silicate (Si) and nitrogen (N).

English

Homa lagoon found in the Izmir bay, Aegean Sea, is important because it is the last lagoon in which fishing activities are carried out. Hantzschia amphioxys species, on which this study was carried on, are benthic diatoms and they are isolated from Homa Lagoon. The Monod equation expressing the nutrient dependency of the growth rates can also be used for carrying capacity (with different parameter values; chl-a max, Ksı). Temporal changes of the calculated maximum chl-a concentrations (carrying capacity) was 115 &micro;g chl-a/L by determining the hyperbolical relations between the maximum biomass levels (biomass carrying capacity) and nutrient concentrations obtained from the phytoplankton growth graphs. &nbsp; Key words: Hantzschia amphioxys, chl-a max, Homa lagoon.

Phytoplankton Distribution and its Relationship to the Physico-Chemical Environment in a Coastal Lagoon

The spatio-temporal variation of the phytoplankton community structure and the environmental factors that affect its distribution and the changes in Homa Lagoon were examined. Sampling took place monthly at four stations between December 2006 and December 2007. During the study period, a total of 58 taxa of which 52 were used as active taxa in the numerical analysis (relative abundance>1%) were from four algal classes, Cyanophyceae, Dinophyceae, Bacillariophyceae, and Euglenophyceae. In general, the most important groups were diatoms and dinoflagellates in terms of species numbers and abundance. The mean Shannon-Weaver’s diversity index (H') and Pielou evenness index (J') values were 2.35 and 0.83, respectively. An abundance of the bloom of certain phytoplankton species, especially Cylindrotheca closterium and Navicula sp., was thought to be the cause of the low diversity index and evenness values. Although nitrogen was thought to be limiting in temperate regions, phosphorus was a limiting factor on the phytoplankton growth in the Homa Lagoon because of the correlation between the abundance and N/P ratio. The relationship between the phytoplankton communities and 10 environmental variables were researched using a canonical correspondence analysis (CCA). According to the Monte Carlo unrestricted permutation test, the temperature and nitrate concentration were the most important variables in accounting for species distribution.

Reproductive biology of the mediterranean green crab Carcinus aestuarii Nardo, 1847 (Crustacea, Brachyura, Portunidae) in Homa Lagoon, Aegean Sea, Turkey

Abstract The Mediterranean green crab Carcinus aestuarii Nardo, 1847 (Crustacea, Brachyura, Portunidae) is a common inhabitant of the shallow waters of Homa Lagoon in Izmir Bay, Turkey, in the eastern Mediterranean. Monthly samples were collected in Homa Lagoon from June 2006 to May 2007 using trammel nets, fyke nets, beach seines and fence traps. In total, 608 males and 559 females of C. aestuarii were collected. The highest sex ratio (81–86% females) was recorded between October and December, and in August (58% females). Ovigerous females were obtained only from November to February with the highest ratio of ovigerous females (55%) observed in January 2007. The maturation curve presenting the carapace width showed that 50% of female crabs with the carapace width of 26.84 ±1.58 mm (r= 0.72) were physiologically mature. Regression analyses indicated that the number of eggs was positively correlated with carapace width and wet weight (P &lt; 0.05, in both cases).

Phytoplankton growth and microzooplankton grazing in the Homa Lagoon (İzmir Bay, Turkey)

Phytoplankton growth and microzooplankton grazing were investigated at one station in the Homa Lagoon from February to January in 2006-2007. Our results showed significant seasonal variations in phytoplankton dynamics. Microzooplankton was mainly composed of dinoflagellates and tintinnid ciliates and nauplii. Microzooplankton grazing increased with increasing of temperature. Grazing rate was maximum levels in spring and summer. Microphytoplankton, which dominated the total algal biomass and production, were characterized by the proliferation of several chain-forming diatoms. Small heterotrophic flagellates and aloricate ciliates were the main controllers of phytoplankton. Phytoplankton represented a significant for micrograzers, which grazing represented 20–120% of diatom and cynabacteria algal production during 2006-2007. Microzooplankton has, however, a relatively high impact on microphytoplankton, as > 45% of microalgal production was consumed throughout the year. These results suggest that the low grazing was one of the factors contributing to the development of the spring bloom. All of seasonal bases, the phytoplankton production were grazed by microzooplankton in summer, autumn and winter– spring seasons have been changing between 20%-120%. The seasonal variation in the microzooplankton grazing pressure seems to result from the dominant size class of the phytoplankton community of this lagoon diatom and cynabacteria.

Carrying capacity of Chaetoceros gracilis in Homa Lagoon and the bay of Izmir

Marine diatom Chaetoceros gracilis has been investigated for its potential use as food in mariculture. In this study, we investigated the effects of temperature, salinity and nutrient on the growth of C. gracilis. The possibility for nutrient limitation to affect C. gracilis was assessed from two different ecosystems (Izmir Bay and Homa Lagoon). Our goal was to determine the growth rate of all nutrients and the maximum levels of the C. gracilis phytoplankton biomass (the maximum biomass carrying capacity) on the extent of its full growth and the level at which the nutrient restrictive growth keeps the biomass (biomass carrying capacity) and the nutrient(s) that sustain its year long growth. Nutrients significantly increased Izmir Bay and Homa Lagoon water’s carrying capacity throughout the year and it was found out that the nutrients which restricted the carrying capacity and the growth rate were nitrogenous compounds.

Factors affecting monthly variation in populationdensity of the capitellid polychaete Heteromastus filiformis in a hyperhaline Mediterranean coastal lagoon

>1-The aim of the study was to elucidate the population ecology of opportunistic species in the Mediterranean coastal lagoon environment by investigating the monthly variation in population density of the capitellid polychaete Heteromastus filiformis and the potential environmental factors affecting it in an eu- to hyperhaline (Homa lagoon, Eastern Aegean Sea) 2-Monthly samplings were conducted from January 2006 to January 2007 3-A Principal Component Analysis (PCA) was conducted using the values of several abiotic variables of the water and sediments. A randomization procedure based on eigenvalues showed the presence of only one significant axis; according to the bootstrapped eigenvector method, salinity and dissolved oxygen were found to load significan**tly on the first axis, having negative and positive weights, respectively 4-Salinity, which exceeded 40 psu all year round except for February-March, peaked in July-September (59-61.5 psu), while dissolved oxygen concentrations were lowest from July to October (2.3-3.9 mg l-1) 5-Population density of H. filiformis was low (21-58 individuals m-2) through most of the year; however, a recruitment was detected in spring (290 ind.m-2) followed by a significant decrease in density in summer 6-Density was significantly correlated with the first PCA component (positive correlation) and with salinity (negative correlation), particularly indicating that (a) relatively lower salinities ( 50 psu) during summer may have negative effects on population density, and (b) salinity effects during summer may have been increased by other simultaneously effective environmental conditions (low oxygen concentrations) 7-Our results indicate that opportunistic species experience extreme environmental conditions, particularly high salinities, during summer in eu- to hyperhaline Mediterranean coastal lagoons, which restrain them to develop highly abundant populations.

An illustrated survey on the morphological characters in three species of the diatom genus Mastogloia (Bacillariophyceae)

The valve morphology of Mastogloia braunii Grunow, Mastogloia pumila Cleve, and Mastogloia vasta Hustedt were investigated using field material. Specimens for study were collected from Homa Lagoon, İzmir Bay, Turkey (4-29 °C; salinity 35%o-54%o) as epipelic and epiphytic (Ulva lactuca L.). The valve morphological characteristics of the 3 species were measured by calibrated ocular micrometer using 20 specimens from each species per station. The valve of M. braunii was 35.15-80.20 µm in length and 12.35-19.85 µm in width, the valve of M. pumila was 13.70-31.85 µm in length and 5.75-9.00 µm in width, and the valve of M. vasta was 31.20-43.35 µm in length and 11.90-18.10 µm in width. The results of Pearson's correlation analysis revealed significant correlations among morphological features and environmental factors. All of the species display a positive correlation between valve length and valve width, and the number of transapical striae in 10 µm are invariable with changes in environmental factors. Seasonal differences in the morphological features of Mastogloia species were determined by one-way ANOVA analyses. Valve length, valve width, and total number of partecta were the common characteristics showing seasonal variation.

Relationship of epilithic diatom communities to environmental variables in Homa lagoon (Izmir, Turkey)

Spatio-temporal changes in taxonomic composition and structure of a diatom com- munity were assessed between June 2006 and June 2007 at the intertidal zone of Homa lagoon, Izmir, Turkey. The communities were composed of a mixture of epilithic, epiphytic, epipsammic, and occasionally some pelagic diatoms. In total, 87 taxa belonging to 39 genera were identified, of which 39 were used as active taxa in the numerical analysis. The Shannon-Wiener diversity index (H') values were quite variable, varying between 1.00 and 3.39 and correlated with both species richness (r = 0.93) and evenness (J'; r = 0.38). Cylindrotheca closterium, Halamphora veneta, Lic- mophora gracilis, L. lyngbyei, Navicula cryptocephala, N. cincta, and N. ramosissima var. mollis were the overall most abundant taxa throughout the sampling. The relationship between epilithic algal communities and 10 environmental variables was explored using canonical correspondence analysis. According to a Monte Carlo unrestricted permutation test, the silicate and ammonium concentrations were the most important variables in accounting for species distribution.

Sediment concentrations of heavy metals in the Homa Lagoon (Eastern Aegean Sea): Assessment of contamination and ecological risks

The concentrations of heavy metals and organic carbon in sediment of the Homa Lagoon which is one of the most productive lagoons and commercial important active fish trap in the Eastern Aegean Sea, were investigated in order to describe the temporal and spatial distributions of metals. These results were used to evaluate possible ecological risks that could be a problem for the environment of the lagoon in the future. Sediments were enriched with Cr, Ni and considered as heavily polluted per the SQG. The Cf of Ni and Cr were presented moderate level of contamination in this area. The Cd levels indicated moderate degree of contamination at station B, C, D and E due to agricultural drainage water, industrial and domestic wastewater, are transported by the Gediz River. Sediments from Homa Lagoon were most toxic for Ni due to exceedances of the TEL and PEL values.