Cnidaria constitute an important phylum of venomous animals, several of which have a significant impact on human health and activities. Cnidarian venoms are included in a special capsule called nematocyst, and are known to consist of peptides, proteins, phospholipids, glycoproteins, sterols, bioactive amines and carbohydrates. Cnidarian venoms are used for hunting and defence, and have paralytic, neurotoxic, cytotoxic, dermotoxic and hemolytic effects on other living organisms. In this study, the neurological and behavioural effects of different doses of venom obtained from the nematocysts of Alicia mirabilis and Aurelia aurita were observed on blue crabs (Callinectes sapidus) individuals. For this purpose, various doses of venoms were injected on the linkage between merus and carpus parts of the cheliped of blue crab individuals. The most common effects of A. mirabilis and A. aurita venoms were observed to be stiffness and trembling behavior in the legs. These symptoms indicate that venom causes neural paralytic syndrome. It has been observed that the effect of venom increases with time and paralysis occurs before death.

Biological invasions are increasingly recognised as a major global change that erodes ecosystems, societal well-being, and economies. However, comprehensive analyses of their economic ramifications are missing for most national economies, despite rapidly escalating costs globally. Türkiye is highly vulnerable to biological invasions owing to its extensive transport network and trade connections as well as its unique transcontinental position at the interface of Europe and Asia. This study presents the first analysis of the reported economic costs caused by biological invasions in Türkiye. The InvaCost database which compiles invasive non-native species’ monetary costs was used, complemented with cost searches specific to Türkiye, to describe the spatial and taxonomic attributes of costly invasive non-native species, the types of costs, and their temporal trends. The total economic cost attributed to invasive non-native species in Türkiye (from 202 cost reporting documents) amounted to US$ 4.1 billion from 1960 to 2022. However, cost data were only available for 87 out of 872 (10%) non-native species known for Türkiye. Costs were biased towards a few hyper-costly non-native taxa, such as jellyfish, stink bugs, and locusts. Among impacted sectors, agriculture bore the highest total cost, reaching US$ 2.85 billion, followed by the fishery sector with a total cost of US$ 1.20 billion. Management (i.e., control and eradication) costs were, against expectations, substantially higher than reported damage costs (US$ 2.89 billion vs. US$ 28.4 million). Yearly costs incurred by non-native species rose exponentially over time, reaching US$ 504 million per year in 2020–2022 and are predicted to increase further in the next 10 years. A large deficit of cost records compared to other countries was also shown, suggesting a larger monetary underestimate than is typically observed. These findings underscore the need for improved cost recording as well as preventative management strategies to reduce future post-invasion management costs and help inform decisions to manage the economic burdens posed by invasive non-native species. These insights further emphasise the crucial role of standardised data in accurately estimating the costs associated with invasive non-native species for prioritisation and communication purposes.

Electronic decision-support tools are becoming an essential component of government strategies to tackle non-native species invasions. This study describes the development and application of a multilingual electronic decision-support tool for screening terrestrial animals under current and future climate conditions: the Terrestrial Animal Species Invasiveness Screening Kit (TAS-ISK). As an adaptation of the widely employed Aquatic Species Invasiveness Screening Kit (AS-ISK), the TAS-ISK question template inherits from the original Weed Risk Assessment (WRA) and related WRA-type toolkits and complies with the ‘minimum requirements’ for use with the recent European Regulation on invasive alien species of concern. The TAS-ISK consists of 49 basic questions on the species’ biogeographical/historical traits and its biological/ecological interactions, and of 6 additional questions to predict how climate change is likely to influence the risks of introduction, establishment, dispersal and impact of the screened species. Following a description of the main features of this decision-support tool as a turnkey software application and of its graphical user interface with support for 32 languages, sample screenings are provided in different risk assessment areas for one representative species of each of the main taxonomic groups of terrestrial animals supported by the toolkit: mammals, birds, reptiles, amphibians, annelids, insects, molluscs, nematodes, and platyhelminths. The highest-scoring species were the red earthworm Lumbricus rubellus for the Aegean region of Turkey and the New Zealand flatworm Arthurdendyus triangulatus for Croatia. It is anticipated that adoption of this toolkit will mirror that of the worldwide employed AS-ISK, hence allowing to share information and inform decisions for the prevention of entry and/or dispersal of (high-risk) non-native terrestrial animal species – a crucial step to implement early-stage control and eradication measures as part of rapid-response strategies to counteract biological invasions.

Alongside climate change, the introduction of non-native species (NNS) is widely recognized as one of the main threats to aquatic biodiversity and human wellbeing. Non-native species and biodiversity are generally low priority issues on the political agendas of many countries, particularly in European countries outside the European Union (EU). The objectives and tasks of this study were to address the policy regulation, education level, education practices, and socioeconomic perceptions of NNS in the Balkans. A questionnaire-based survey was conducted in Albania, Bosnia and Herzegovina, Montenegro, North Macedonia and Turkey (Balkan EU candidate and potential candidate members), in Croatia and Greece (Balkan EU Member States) and Italy (non-Balkan EU Member State). The EU Alien Regulation (1143/2014) concerning NNS is implemented in EU Member States and Montenegro, whereas Albania, Bosnia and Herzegovina and Turkey have not reported specific policy regulations for NNS. Permanent monitoring programmes specifically designed for NNS have not yet been established in the EU Member States. Most countries tackle the issue of NNS through educational activities as part of specific projects. Education level is indicative of the implementation of NNS policy regulation, and efforts are needed for the proper development of relative study programmes. Public awareness and educational preparedness concerning NNS in the Balkans were identified as poor. Strong programmes for management and education should be developed to increase public awareness to prevent further biodiversity losses in the Balkan region.

Human-induced biological introductions pose a major threat to global biodiversity, and this is especially frequent in the eastern Mediterranean region, which is a globally important biodiversity hotspot area of high conservation value. To predict at which level introduced species in this region might become invasive under current and projected climate conditions, 232 non-native aquatic organisms were screened using the Aquatic Species Invasiveness Screening Kit. Based on receiver operative characteristic curve analysis, thresholds were identified to distinguish between low, medium and high risk species. The “top invasive” (very high risk) species identified were: brown bullhead Ameiurus nebulosus, blue crab Callinectes sapidus, gibel carp Carassius gibelio, Philippine catfish Clarias batrachus, Chinese mitten crab Eriocheir sinensis, bluespotted cornetfish Fistularia commersonii, silver carp Hypophthalmichthys molitrix, silver-cheeked toadfish Lagocephalus sceleratus, half-smooth golden pufferfish Lagocephalus spadiceus, Suez pufferfish Lagocephalus suezensis, signal crayfish Pacifastacus leniusculus, fathead minnow Pimephales promelas, channeled applesnail Pomacea canaliculata, red swamp crayfish Procambarus clarkii, devil firefish Pterois miles and European catfish Silurus glanis. The risk of being invasive of more than half of the screened species increased after taking global warming predictions into account, and several species considered to be globally invasive (cf. high risk) were classified as posing only a medium risk for the eastern Mediterranean region. Region-specific risk screenings, as implemented in this study, are therefore essential for setting priorities in preventative management for the conservation of key biodiversity hotspots and the optimal allocation of resources in view of full risk assessment for the species identified as (very) high risk.

In this study, it was aimed to determine the nematocyst types and morphologies and the relationship between the bell diameters and nematocyst numbers of some scyphozoa species in coasts, Turkey. Three scyphozoa species which are Cotylorhiza tuberculata (Macri, 1778), Phyllorhiza punctata Lendenfeld, 1884 and Chrysaora hysoscella (Linne, 1766) were sampled in coasts. Four different methods were experimented for nematocyst isolation but it was determined that the most effective method was the tissues were homogenized and then centrifuged. Four and seven nematocyst types were identified in C. tuberculata and P. punctata, respectively. Generally, euryteles were the most common nematocyst types in P. punctata and O-isorhizas were the dominant types in C. tuberculata samples. Five nematocyst types identified which were a-isorhiza, A-isorhiza, O-isorhiza, eurytele and polyspiras in C. hysoscella. In C. tuberculata, correlations between bell diameters and numbers of nematocyst types were found in A-isorhiza and O-isorhiza (r=0,95; r=0,39, respectively) in margins and in all nematocyst types except O-isorhiza in oral arms. In P. punctata, only correlation was found between the numbers of O-isorhiza and bell diameters (r=0,53) in the margin. In oral arms, numbers of a-isorhiza and O-isorhiza were correlated with bell diameters (r=0,74, r=0,56, respectively).

The threat posed by invasive non-native species worldwide requires a global approach to identify which introduced species are likely to pose an elevated risk of impact to native species and ecosystems. To inform policy, stakeholders and management decisions on global threats to aquatic ecosystems, 195 assessors representing 120 risk assessment areas across all six inhabited continents screened 819 non-native species from 15 groups of aquatic organisms (freshwater, brackish, marine plants and animals) using the Aquatic Species Invasiveness Screening Kit. This multi-lingual decision-support tool for the risk screening of aquatic organisms provides assessors with risk scores for a species under current and future climate change conditions that, following a statistically based calibration, permits the accurate classification of species into high-, medium- and low-risk categories under current and predicted climate conditions. The 1730 screenings undertaken encompassed wide geographical areas (regions, political entities, parts thereof, water bodies, river basins, lake drainage basins, and marine regions), which permitted thresholds to be identified for almost all aquatic organismal groups screened as well as for tropical, temperate and continental climate classes, and for tropical and temperate marine ecoregions. In total, 33 species were identified as posing a 'very high risk' of being or becoming invasive, and the scores of several of these species under current climate increased under future climate conditions, primarily due to their wide thermal tolerances. The risk thresholds determined for taxonomic groups and climate zones provide a basis against which area-specific or climate-based calibrated thresholds may be interpreted. In turn, the risk rankings help decision-makers identify which species require an immediate 'rapid' management action (e.g. eradication, control) to avoid or mitigate adverse impacts, which require a full risk assessment, and which are to be restricted or banned with regard to importation and/or sale as ornamental or aquarium/fishery enhancement.

Objective: A freshwater jellyfish Craspedacusta sowerbii is frequently found in disturbed or artificial bodies of water, e.g. quarry ponds and gravel pits, reservoirs, aquaria and even wastewater treatment facilities, it can also thrive in natural lentic and lotic habitats. In the present study, we present two new records for C. sowerbii which is non-native to Turkey and provide the distribution data of the species in Turkey and Europe. Materials and Methods: The jellyfish samples were obtained from two localities by fishing nets and hand net. Temperature, pH and dissolved oxygen values of the two sampling areas were measured in both of the sampling areas. Results: Non-native freshwater jellyfish Craspedacusta sowerbii is recorded from two different localities namely Akdeğirmen Reservoir (Afyon) and Atabey Reservoir (Isparta) in Turkey. Twelve individuals and two individuals of C. sowerbii were sampled in Akdeğirmen Reservoir (Afyon) and Atabey Reservoir (Isparta), respectively. Temperature, pH and dissolved oxygen values of the two sampling areas were 18.7ºC, 7.9, 6.34 mg/l in Akdeğirmen Reservoir, and 10.9ºC, 7.94, 9.36 mg/l in Atabey Reservoir. Conclusion: Many studies suggested that it could tolerate a wide range of temperatures from 10°C to 28°C and spread by fish stocking activities as well as by migratory birds in Turkey. It may have been possible for Craspedacusta sowerbii to be introduced to Akdeğirmen Reservoir where there are many actively moving cormorants colonies. Also, spread of this species may have been facilitated by fish stocking activities in Turkish inland waters.

Abstract In order to understand the effects of some physical (temperature and salinity) and chemical (dissolved oxygen, nitrate and chlorophyll a) factors on the abundance and distribution of cladoceran species, zooplankton samples were seasonally collected between August 2015 and July 2016 from three stations near the entrance to the Boğaziçi Lagoon in Güllük Bay (Aegean Sea, Turkey) using a WP2 plankton net with a mesh size of 200 μm. Four cladoceran species – Penilia avirostris, Pseudevadne tergestina, Evadne spinifera and Pleopis polyphemoides – were found during all sampling events throughout the study period. They showed high abundance in August (4774 ind. m−3) and October (10 706 ind. m−3) as the dominant zooplankton group. The abundance of Penilia avirostris – the dominant cladoceran at all sampling locations – was estimated up to 10 871 ind. m−3 in October. Pseudevadne tergestina was the second dominant cladoceran. In September, only Pseudevadne tergestina and Pleopis polyphemoides were found in samples in small numbers. The abundance of cladocerans varied significantly throughout the seasons. Two physicochemical factors, temperature and dissolved oxygen, were the main drivers of changes in the cladoceran composition.

Seasonal meroplankton abundances of Köyceğiz-Dalyan Lagoon System were examined in this study. Also, changes in the diversity and abundance of meroplanktonic larvae because of the different two salinity layers of the system were investigated. Meroplankton samples were taken by Unesco standart plankton net with 200 micrometer mesh size horizontally from three stations. Temporal and spatial differences in the abundance of meroplankton groups were examined by permutational multivariate analysis of variance (PERMANOVA). Environmental parameters which are temperature, salinity and dissolved oxygen were measured from the surface. Meroplankton groups of the study area were nauplius, zoea, cyprid larva, stomatopod larva, hydrozoan larva, ephyra, polychaeta larva, fish egg, fish larva and gastropod larva. Meroplankton and holoplankton abundances showed two peaks in April and October. There were statistically significant differences in the abundance of meroplankton amongst seasons especially between summer-winter and winter-spring. In October and November Mediterranean water enters the Köyceğiz-Dalyan Lagoon System through the bottom of the system, whereas in winter and spring, the lagoon and coastal zone were under the influence of Lake Köyceğiz.

The aim of the present study was to risk screen 45 jellyfish species (30 hydromedusae, 14 scyphomedusae, one cubomedusa) for their potential invasiveness in the Mediterranean Sea to aid managers in making informed decisions on targeting appropriate species for management. Using the Aquatic Species Invasiveness Screening Kit (AS-ISK), calibrated basic and climate-change threshold assessment scores of 6.5 and 12.5, respectively, were identified for distinguishing reliably between species that pose 'low-to-medium' and 'high' risk of becoming invasive in the risk assessment area. Using these thresholds, 16 species were classified as high risk, 23 as medium risk and six as low risk under current climate conditions. Whereas, under future climate conditions, 13, 30 and two species, respectively, were classified as high, medium and low risk, respectively. Upside-down jellyfish Cassiopea andromeda, Australian spotted jellyfish Phyllorhiza punctata, sea nettle Chrysaora quinquecirrha and Rhopilema nomadica were the highest-scoring species, with the maximum increase in risk score under predicted climate change conditions being achieved by C. andromeda.

Natural substances produced by venomous marine organisms are thought to be possible sources of useful compounds and new drugs having the potential to open new ways for pharmacology, nutrition and environmental applications. In this framework, cnidarians are very interesting being widely distributed and all are venomous organisms; so, a deep knowledge of their occurrence, morphology of venomous structures and of effects of venoms at cellular level is fundamental to evaluate the possible utilization of venomous compounds or extracts. In this research, the morphology and occurrence of nematocysts in two cnidarian species (Aurelia aurita, Velella velella), and the preliminary evaluation of the cytotoxicity of V. velella crude extract, of which cytotoxicity on cell cultures at present is unknown, were considered. The specimens were sampled in Güllük Bay, Southwestern coast of Turkey, and in the Gulf of Genova, Northwestern coast of Italy. Six nematocyst types (a-isorhiza, A-isorhiza, O-isorhiza, eurytele, polyspiras, birhopaloid) having different sizes, were observed in A. aurita, and two types (eurytele and stenotele) in V. velella. The crude extract from V. velella showed cytotoxic activity against cultured fibroblasts L929 at high doses, while inducing cell proliferation at low doses. The protein content in the extract increased remarkably after disruption of nematocysts.

In this study, seasonal abundances and distribution of Cladocera species were investigated in Gulluk Bay, Mugla. Sampling operations were performed in four stations during April-October 2017. Zooplankton samples were taken horizontally by WP2 UNESCO plankton net with 200 micrometer mesh size. Five Cladocera species which are P. avirostris, P. tergestina, E. spinifera, P. polyphemoides, P. intermedius were determined in the study area. Other zooplankton groups in the samples were copepods, appendicularians, chaetognaths and meroplankton. P. polyphemoides was found in all sampling months except July. Maximum mean abundance of P. polyphemoides was observed 317 ind./m³ in April. P. avirostris showed maximum abundances in May and June but these values were not very high. P. intermedius was found in September and October in the samples. P. tergestina was dominant Cladocera species in May, June, July, August and September. Maximum abundance of E. spinifera was determined in June (mean 105 ind./m3).

Cnidarians play an important role in ecosystem functioning, in the competition among species, and for possible utilization of several active compounds against cardiovascular, nervous, endocrine, immune, infective, and inflammatory disorders or having antitumoral properties, which have been extracted from these organisms. Nevertheless, notwithstanding these promising features, the main reason for which cnidarians are known is due to their venomousness as they have a serious impact on public health as well as in economy being able to affect some human activities. For this reason a preeminent subject of the research about cnidarians is the organization of proper systems and methods of care and treatment of stinging. This chapter aims to present the data about the morphological, ecological, toxicological, epidemiological, and therapeutic aspects regarding cnidarians with the purpose to summarize the existing knowledge and to stimulate future perspectives in the research on these organisms.

This study is about a questionnary developed to collect data related awareness of people about jellyfish and injury cases.The questionnary was distributed to 226 people in the touristic areas of the west and the southwest regions of Turkey, with the participants consisting of holiday-makers, people working in the tourism sector, fishermen, divers as well as local dwellers.Overall, 78% of the participants had previous awareness of the existence of jellyfish, whereas the remaining 22% had heard about jellyfish for the first time only.The most known jellyfish species were Aurelia aurita, Cotylorhiza tuberculata, Chrysaora hysoscella and Rhizostoma pulmo.In total, 42% of the participants had run into jellyfish at least on one occasion before.The most common injuries were erythema, itching and blistering, and two people retained scars caused by Pelagia noctiluca.Of the participants that were injured by jellyfish, 91% did not seek hospitalisation or health care, 76% were unaware of the measures necessary following jellyfish injury, and 96% of those who spotted jellyfish whilst swimming or from the beach did not inform any academic institution or research organisation.Since jellyfish form swarms that are usually carried around randomly by currents, it is mandatory that people be informed about jellyfish blooms and possible related injuries.This is especially important since jellyfish injury cases are generally not being recorded from hospitals and health care providers throughout Turkey.The present questionnary-based study has shown that even people affected by jellyfish injuries fail to notify relevant institutes or organisations.Further questionnaries and related projects should be implemented so as to collect data of jellyfish injuries and to increase people's awareness of jellyfish-related risks in other parts of Turkey.