Su Ürünleri Fakültesi

Predicting the potential implications of perch (Perca fluviatilis) introductions to a biodiversity-rich lake using stable isotope analysis

Sun, 01 Jan 2023 00:00:00 GMT

Predicting the potential implications of perch (Perca fluviatilis) introductions to a biodiversity-rich lake using stable isotope analysis Tarkan, Ali Serhan; Haubrock, Phillip J.; Aksu, Sadi; Mol, Oğuzcan; Balzani, Paride Biological invasions, particularly of fish species, significantly threaten aquatic ecosystems. Among these invaders, the introduction of the European perch (Perca fluviatilis) can have particularly detrimental effects on native communities, affecting both ecosystem functioning and human well-being. In this study, carbon and nitrogen stable isotope analysis was employed, using perch originating from five different ecosystems, to model the effects of their hypothetical introduction into İznik Lake, an economically and ecologically important, biodiversity-rich lake in northern Turkey, to ultimately assess their potential predation impact and competition with native predators. The results revealed that if perch were introduced to the community, they would - considering gape size limitations - primarily prey upon Vimba vimba and Rutilus rutilus, indicating a significant feeding pressure on these species. Furthermore, the study identified a potential overlap and competition for resources between commonly mesopredator perch and the European catfish Silurus glanis, the current top predator in the ecosystem. Both species would occupy top predatory positions, emphasizing the potential disruption of predator-prey dynamics. Our findings underscore the potential ecological repercussions of perch invasions. The selective predation on V. vimba and R. rutilus, with the latter being consumed to a lesser extent by perch, could lead to cascading effects throughout the food web, altering the community structure, and ecosystem dynamics. Additionally, the competition between perch and S. glanis raises concerns about effects on the stability and functioning of the fish community. These results highlight the need for proactive management strategies to mitigate the risk of perch introductions. Strict regulations on the movement and introduction of invasive species, along with comprehensive monitoring, are crucial for preserving native communities and maintaining the ecological integrity of freshwater ecosystems. Our study demonstrates the potential predation impact of perch on vulnerable fish species and the competition with the established apex predator, emphasizing the importance of considering the ecological consequences of perch invasions and informing management decisions to ensure the conservation and sustainability of aquatic ecosystems.

The neglect of nonnative orthopterans as potential invaders: A call for awareness

Sun, 01 Jan 2023 00:00:00 GMT

The neglect of nonnative orthopterans as potential invaders: A call for awareness Kulessa, Anna K.; Balzani, Paride; Soto, Ismael; Kouba, Antonín; Renault, David; Tarkan, Ali Serhan; Haubrock, Phillip J. Despite the potential ecological and economic impacts of invasive species, there is a dearth of data on the presence, impacts, and management implications of potentially invasive Orthoptera species. This lack of research and inconsistent data, including risk screenings and impact assessments, is especially evident in Europe. Consequently, assessing the status, distribution, and potential threats of nonnative Orthoptera in Europe remains challenging, impeding the development of effective management strategies. To address this gap, we call for increased efforts to collect and curate data on non-native and possibly invasive Orthoptera in Europe. Such efforts will improve our understanding of this order's invasion dynamics, facilitate the identification of priority areas for conservation, and support the development of effective management policies and preventive measures.

Critical temperatures and aerobic metabolism in post-larvae of Pacific white shrimp Litopenaeus vannamei (Boone, 1931)

Sun, 01 Jan 2023 00:00:00 GMT

Critical temperatures and aerobic metabolism in post-larvae of Pacific white shrimp Litopenaeus vannamei (Boone, 1931) Topuz, Mustafa; Kır, Mehmet Increasing water temperature because of climate change decreases the oxygen concentration while increasing the oxygen requirement of species in aquatic environments. Temperature is one of the most important environmental factors affecting the physiological functions of organisms, especially poikilothermic animals, such as shrimp at all levels. In intensive shrimp culture, it is of great importance to know the tolerable temperature range of cultured species and their metabolism since this affects the physiological condition. In this study, critical temperatures (CTM: CTmin and CTmax) of Pacific white shrimp, Litopenaeus vannamei, post-larvae (PL), were determined at different acclimation temperatures of 15, 20, 25, and 30 °C. Lower and upper incipient lethal temperatures (ILT: LILT and UILT) were also calculated for the PL. The thermal windows of the PL were developed using the CTM and ILT values. The standard metabolic rate (SMR) of the PL was determined based on the oxygen consumption rate (OCR) at the different acclimation temperatures mentioned above. The acclimation temperature had a subsequent effect on the thermal tolerance and SMR of the PL (P < 0.01). The PLs of Pacific white shrimp have high thermal tolerance and can survive at extreme temperatures (CTmin and CTmax: 8.2–43.8 °C) with their large dynamic and static thermal window areas of 1128 and 931 °C2, respectively. The optimal temperature range for Pacific white shrimp PLs is the 25–30 °C range, where a decrease in SMR is determined with increasing temperature. The result of this study reveals that a range of 25–30 °C is optimal for effective PL culture of Pacific white shrimp

Is the Nutritional Composition of Safflower Oilseed Meal Sufficient for Alternative or Complementary Aqua Feeds-raw Material? Send mail to Yildirim Ö.;

Sun, 01 Jan 2023 00:00:00 GMT

Is the Nutritional Composition of Safflower Oilseed Meal Sufficient for Alternative or Complementary Aqua Feeds-raw Material? Send mail to Yildirim Ö.; Yıldırım, Önder; Çantaş, İsmail Berat Safflower (Carthamus tinctorius L.) is grown in many countries, even in arid regions. Due to its important nutrients, safflower has the potential to be used as raw material for the nutrition of many animals and aquaculture species. For this reason, the objective of this study is to determine crude protein, crude oil, ash, and nitrogen-free extract (NFE) values, as well as amino acid, fatty acid, and mineral values in safflower seed meal. In addition, fish meal, soybean meal, wheat, and canola meal values are compared with safflower seed. On a dry matter basis, the crude protein, crude oil, crude ash, and NFE values were found at 19.42% ±0.32, 8.76% ±0.21, 2.82% ±0.1, and 62.68% ±0.88 respectively. Safflower meal contains significant arginine, histidine, and phenylalanine levels, with C18:2 n-6 being one of the most abundant fatty acids. According to the fatty acid values examined, the total saturated fatty acid values were to be 9.79%; the total monounsaturated fatty acid values are 27.58%; total n-6 PUFA values are 61.49%; total n-3 fatty acid values are 0.55% and total n-3 HUFA values are 0.22% in safflower oilseed meal. The potassium and magnesium content in safflower seed meal is similar to that of soybean meal and fishmeal. Safflower oilseed meal or oil can be used as complementary feedstuff in both marine and freshwater fish feeds. In future studies, observing the balance of essential amino acids and polyunsaturated fatty acids and conducting detailed studies will be effective in closing the gap in this area.