Assessing the Fisheries and Ecosystem Structure of the Largest Greek Lake (Lake Trichonis)

Olga Petriki,Roberta Barbieri,Georgia Papantoniou,Konstantinos Tsagarakis,Irene Mantzouni,Ioanna Tsionki,Dimitrios K Moutopoulos,Maria Th Stoumboudi

doi:10.3390/w13233329

Olga Petriki, Roberta Barbieri + Show 6 more

Open Access

https://doi.org/10.3390/w13233329

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Abstract

An Ecopath with Ecosim (EwE) modeling approach was used to explore the ecological structure of the largest lake in Greece (Lake Trichonis). Until the mid-1990s, the lake was receiving a high level of pollution and the fishing pressure was intense, while since the early 2000s, fisheries and other human pressures gradually declined. Nowadays, the lake’s fisheries mainly target Atherina boyeri due to the absence of market demand for the other fish species in the lake, resulting in a low overall fisheries pressure on the fish stocks. The model was built with data collected through: (a) field samplings, (b) in-depth targeted interviews of professional fishermen and (c) historical archive information. The model considered 22 functional groups, while fishing activities were represented by three classes according to the used gears. The outputs of the model revealed that the ecosystem is dominated by low trophic level species (also identified as keystone species), indicating the significance of bottom-up control in the regulation of food web processes. Ecological indicators depicted that the lake’s ecosystem is mature and resilient to external disturbances. The methodological approach used in this study was shown to be helpful for studies addressing ecosystem structure, in particular with limited data availability.

Highlights

Habitat loss and degradation, species invasions, pollution, overexploitation and climate change have raised concern for the management of freshwater ecosystems and the protection of the life that they support (e.g., [1–3])
Ecopath with Ecosim (EwE) models have been developed for quantifying the impact of fisheries management strategies, such as changes in fisheries regulations and enhancement of fish stocks on the aquatic community
EwE models have been applied to a wide variety of ecosystems worldwide [6], their application in freshwater ecosystems and especially in lentic European water bodies remains scarce (Ijsselmeer in Netherlands: [7], Lake Aydat in France: [8], Lake Volvi in Greece: [9])

Summary

Introduction

Species invasions, pollution, overexploitation and climate change have raised concern for the management of freshwater ecosystems and the protection of the life that they support (e.g., [1–3]). Within this framework, the Ecopath with Ecosim (EwE) methodology gained attention by providing a useful tool for depicting freshwater food webs and evaluating the impacts of anthropogenic stressors on specific groups of organisms or the whole ecosystem [4]. EwE models have been developed for quantifying the impact of fisheries management strategies, such as changes in fisheries regulations and enhancement of fish stocks on the aquatic community Their use aims to determine the appropriateness of particular management actions [5] and establish more effective and feasible strategies by incorporating interspecific interactions of all involved organisms and their habitat. EwE models have been applied to a wide variety of ecosystems (i.e., open sea, coastal areas, estuaries, lakes, rivers) worldwide [6], their application in freshwater ecosystems and especially in lentic European water bodies remains scarce (Ijsselmeer in Netherlands: [7], Lake Aydat in France: [8], Lake Volvi in Greece: [9]). 4.0/).

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