Trophic State Evaluation of a Large Mediterranean Lake Utilizing Abiotic and Biotic Elements

Kehayias, George; Doulka, Evangelia

doi:10.4236/jep.2014.51003

Cited by 15 publications

(14 citation statements)

References 25 publications

(50 reference statements)

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“…It is a deep (Z max = 57 m, Z mean = 29 m), warm monomictic lake, exhibiting a long period of thermal stratification. It is an oligo-to mesotrophic ecosystem and has great ecological importance and is included in the Natura 2000 protection network (Kehayias and Doulka 2014). The lake is very rich in fish species, among which Atherina boyeri dominates (Leonardos 2001).…”

Section: Methodsmentioning

confidence: 99%

Fish predation in the proximity of purse seine fishing lights: The case of Atherina boyeri (Actinopterygii: Atheriniformes: Atherinidae) in a Greek Lake

Kehayias¹,

Tzavali²,

Gini³

et al. 2018

Acta Ichthyol. Piscat.

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Kehayias G., Tzavali A., Gini M., Michopoulou E., Tsounis L. 2018. Fish predation in the proximity of purse seine fishing lights: The case of Atherina boyeri (Actinopterygii: Atheriniformes: Atherinidae) in a Greek Lake. Acta Ichthyol. Piscat. 48 (1): 51-60.Background. Purse seining with the use of light is among the most common fishing practices around the world, but there is lack of studies on the effect of light on the feeding of the target species in this kind of fishery and the possible consequences for other prey species. The presently reported investigation intended to provide indications on this issue by studying the diet of Atherina boyeri Risso, 1810, which is the target species of professional purse seine fishery, conducted using light in Lake Trichonis (Greece), and by comparing the acquired results with those of previous studies where the samples were taken without using light. Materials and methods.A seven-month (June through December 2014) purse seining fishing was conducted at night around two lamp rafts: 1) a traditional lamp raft producing white LED light and 2) an autonomous photovoltaic-battery-LED lamp raft producing green LED light. Stomach content analysis was conducted on 100 randomly selected specimens from each sample and the relative prey abundance and frequency of occurrence for each prey category was estimated. Calculations of predation pressure of A. boyeri upon the fish larvae of a goby, Economidichthys trichonis Economidis et Miller, 1990, were performed. Results. The study revealed the intense effect of light on the attraction and capture of prey species rarely found in previous studies, such as the larvae of the native and endangered fish E. trichonis, amphipods, and copepod nauplii. No significant differences were observed between the two light colours. A preference shift to larger prey with the increase of ontogenetic stage of A. boyeri was observed. Several thousands of pre-recruited E. trichonis larvae may be preyed upon each night around a single lamp especially during summer. Conclusion. Fishing with light may alter the dietary preference of the target fish species and even of the entire fish community. This may have serious consequences on the younger ontogenetic stages of other fish populations, especially when it coincides with their reproductive period. Considering the lack of similar field studies, the present results may stimulate analogous investigations on the effects of fishing lights in other marine and freshwater ecosystems worldwide.

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Section: Methodsmentioning

confidence: 99%

Fish predation in the proximity of purse seine fishing lights: The case of Atherina boyeri (Actinopterygii: Atheriniformes: Atherinidae) in a Greek Lake

Kehayias¹,

Tzavali²,

Gini³

et al. 2018

Acta Ichthyol. Piscat.

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“…Lake Trichonis is Greece's largest natural lake, covering an area of 98.6 km 2 and having a catchment area of 421 km 2 . It is a warm monomictic lake with oligotrophic to mesotrophic characteristics and a maximum depth of 57 m (Doulka and Kehayias 2008;Kehayias and Doulka 2014). Lake Ozeros is a karstic lake covering an area of 10.1 km 2 and having a catchment area of 59 km 2 .…”

Section: Study Areamentioning

confidence: 99%

Alteration of the feeding behavior of an omnivorous fish, Scardinius acarnanicus (Actinopterygii: Cypriniformes: Cyprinidae), in the presence of fishing lights

Tsounis¹,

Kehayias²

2021

AIeP

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Fishing with light is an old and common practice yielding a substantial catch volume globally. Despite the popularity of the method and the efforts to improve it, there is a lack of field studies on the effects of light on the feeding preferences of the attracted fishes. A previous report suggested that purse seine fishing lights can differentiate the feeding preferences of the approaching fishes, such as Atherina boyeri Risso, 1810 in Lake Trichonis (Greece). The presently reported study aims to verify these findings by investigating the diet of the endemic Scardinius acarnanicus Economidis, 1991. The feeding behavior of S. acarnanicus was studied from 2016 to 2019 through gut content analysis, in specimens from Lake Trichonis that came from purse seining with light and specimens caught without light. The same investigation was carried out comparatively in specimens taken by gillnets from two nearby lakes (lakes Ozeros and Amvrakia), where S. acarnanicus is present, but no fishing with light is exercised. The stomach content analysis conducted on 699 S. acarnanicus specimens revealed the intense effect of light on its diet resulting in the alteration of its feeding habits towards fish predation and especially Atherina boyeri. On the contrary, the specimens taken with the use of gillnets, from the three lakes, showed a typical omnivorous feeding behavior. The findings of the presently reported study support the assumption that the elevated concentration of fish close to fishing lights alters the feeding behavior of certain species making them predators. Considering that fishing with light is practiced worldwide, this could be of great ecological significance to the ichthyofauna not only of inland waters but also of marine areas, affecting perhaps several commercial species.

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“…In this respect, researches in water quality are important to increase the awareness of more efficient use of water and water resources that are the most precious treasure of humankind [6]. Several indexes have been developed to assess eutrophication and water quality in aquatic ecosystems based on chemical, physical and biological parameters [7]. Carlson's trophic state index (TSI) is the most widely used in freshwater bodies [8].…”

Section: Introductionmentioning

confidence: 99%

Water Quality Monitoring in Kpassa Reservoir (Northen Benin): Physico-Chemical Parameters, Trophic State and N: P Ratio

Boukari¹,

Bawa²,

Mama³

et al. 2018

WROS

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The study was carried out to assess the physico-chemical parameters, the trophic state and the N:P ratio of the Kpassa reservoir. The reservoir was studied at six sampling sites over the period going from August 2014 to May 2016. Water transparency was determined in situ with the secchi disk SDMO QUINIOU model F043SE. Chlorophyll a, NO 3-, NO 2-, NH 4 + , PO 4 3and total phosphorus were analyzed using the standard methods. Measures were made with the HACH DR2800 spectrophotometer. The trophic state was assessed using the Carlson's trophic state index (TSI). The N:P ratio was evaluated using NO 3-, NO 2-, NH 4 + and PO 4 3concentrations. The physico-chemical parameters investigated were: transparency (0.25-1.92m), chlorophyll a (8.2-233.46µg/L), nitrate (undetected-4.73mg/L), nitrite (undetected-0.23mg/L), ammonia (undetected-0.21mg/L), orthophosphate (0.03-1.04mg/L) and total phosphorus (0.1-3.2mg/L). The trophic state index (TSI) values oscillate between 38 and 59. The majority of the values are characteristic of mesotrophic conditions. Kpassa reservoir is eutrophic only in August 2014 at the whole studied stations. N:P ratio values vary between 0.22 and 60.46 showing that eutrophication in Kpassa reservoir is limited by phosphorus and nitrogen. Some physico-chemical parameters values are upper than the WHO and Ifremer safe limit making the reservoir water unfit for human consumption at the concerned sites and during the concerned period. It is recommended that the national company of Benin water (SONEB) sensitize the population on the rational use of the fertilizers and the adoption of water control technics in the farm. Washing and crockery activities should be also forbidden along the reservoir river. The trophic state of the reservoir seems improved compared to previous studies results. According to the N: P ratio values, measurements to be implemented for eutrophication management in Kpassa reservoir should emphasize on the control of the flow of nitrogen and phosphorus compounds.

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Trophic State Evaluation of a Large Mediterranean Lake Utilizing Abiotic and Biotic Elements

Cited by 15 publications

References 25 publications

Fish predation in the proximity of purse seine fishing lights: The case of Atherina boyeri (Actinopterygii: Atheriniformes: Atherinidae) in a Greek Lake

Fish predation in the proximity of purse seine fishing lights: The case of Atherina boyeri (Actinopterygii: Atheriniformes: Atherinidae) in a Greek Lake

Alteration of the feeding behavior of an omnivorous fish, Scardinius acarnanicus (Actinopterygii: Cypriniformes: Cyprinidae), in the presence of fishing lights

Water Quality Monitoring in Kpassa Reservoir (Northen Benin): Physico-Chemical Parameters, Trophic State and N: P Ratio

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