Raya Bandung Sumedang Km. 21 Jatinangor

Abstract. Sunardi, Yoshimatsu T, Junianto N, Istiqamah N, DeWeber T. 2016. Long-term variability of zooplankton community under climate warming in tropical eutrophic man-made lake. Biodiversitas 17: 626-633. The climate warming is increasingly acknowledged as an important driver of lake ecosystems. However, there are no generic patterns of how the aquatic species/community responds the warming climate; instead the changes are complicated by interactions of many factors. To regard the important role of zooplankton in the lake ecosystems, this paper questions whether the climate warming affects their community structure in tropical eutrophic man-made lake. We analyzed a series of data resulted from a long water quality monitoring activities in the Cirata Lake, Indonesia. We anticipated that there would be a strong association between the climates warming with the response of zooplankton community after 19 years. Our result suggested that the lake has been becoming slightly warmer following the atmospheric temperature. Instead of decreasing, the shifting water temperature tend promotes a greater species richness, density, and diversity of the zooplankton. Relevant changes in species composition have been observed. It seems that the magnitude of the shift of the temperature, and the eutrophication status played an important role in shaping the changes of the zooplankton community structure

Long-term changes in body condition and gillnet selectivity in Lake Constance pelagic spawning whitefish (Coregonus wartmanni)

The body condition of Lake Constance pelagic spawning whitefish (Coregonus wartmanni) has changed substantially during the past century and altered the length-based selectivity of gillnets. Linked hierarchical models using Bayesian inference and error propagation were used to estimate the monthly body condition of whitefish from 1932 to 2018 and condition-dependent gillnet selectivity from 1964 to 2018. As expected, body condition followed past trends in nutrient dynamics and was highest in summer months. Body condition was clearly linked to gillnet selectivity, with a weight increase of a 300 mm whitefish from 205 to 260 g predicted to reduce the mean (from 374 to 330 mm) and standard deviation (from 30.8 to 25.1 mm) of lengths selected by a 38 mm mesh gillnet. Simulations demonstrate that such changes can reduce the mean age in harvest by over 1 year and greatly bias population age distribution estimates if selectivity changes are ignored. Similar variation in gillnet selectivity is expected where trophic conditions or other factors cause body condition differences, and accounting for these changes could reduce biases to inform fishery management.publishe

Long term changes in body condition and gillnet selectivity in Lake Constance pelagic spawning whitefish Coregonus wartmanni

The body condition of Lake Constance pelagic spawning whitefish Coregonus wartmanii has changed substantially during the past century and significantly altered the length-based selectivity of gillnets. Linked hierarchical models using Bayesian inference and error propagation were used to estimate the monthly body condition of whitefish from 1932-2018 and condition-dependent gillnet selectivity from 1964-2018. As expected, body condition followed past trends in nutrient dynamics and was highest in summer months. Body condition was clearly linked to gillnet selectivity, with a weight increase of a 300 mm whitefish from 205 to 260 g predicted to reduce the mean (from 374 to 330 mm) and standard deviation (from 30.8 to 25.1) of lengths selected by a 38 mm mesh gillnet. Simulations demonstrate that such changes can reduce the mean age in harvest by over 1 year and greatly bias population age distribution estimates if selectivity changes are ignored. Similar variation in gillnet selectivity is expected where trophic conditions or other factors cause body condition differences, and accounting for these changes could reduce biases to inform fishery management.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Long-term variability of zooplankton community under climate warming in tropical eutrophic man-made lake

Sunardi, Yoshimatsu T, Junianto N, Istiqamah N, DeWeber T. 2016. Long-term variability of zooplankton community under climate warming in tropical eutrophic man-made lake. Biodiversitas 17: 634-641. The climate warming is increasingly acknowledged as an important driver of lake ecosystems. However, there are no generic patterns of how the aquatic species/community responds the warming climate; instead the changes are complicated by interactions of many factors. To regard the important role of zooplankton in the lake ecosystems, this paper questions whether the climate warming affects their community structure in tropical eutrophic man-made lake. We analyzed a series of data resulted from a long water quality monitoring activities in the Cirata Lake, Indonesia. We anticipated that there would be a strong association between the climates warming with the response of zooplankton community after 19 years. Our result suggested that the lake has been becoming slightly warmer following the atmospheric temperature. Instead of decreasing, the shifting water temperature tend promotes a greater species richness, density, and diversity of the zooplankton. Relevant changes in species composition have been observed. It seems that the magnitude of the shift of the temperature, and the eutrophication status played an important role in shaping the changes of the zooplankton community structure

All day-long : Sticklebacks effectively forage on whitefish eggs during all light conditions

The three-spined stickleback Gasterosteus aculeatus invaded Lake Contance in the 1940s and expanded in large numbers from an exclusively shoreline habitat into the pelagic zone in 2012. Stickleback abundance is very high in the pelagic zone in winter near the spawning time of pelagic whitefish Coregonus wartmanni, and it is hypothesized that this is triggered by the opportunity to consume whitefish eggs. Field sampling has qualitatively confirmed predation of whitefish eggs by stickleback, but quantification has proven difficult due to stormy conditions that limit sampling. One fundamental unknown is if freshwater stickleback, known as visual feeders, can successfully find and eat whitefish eggs during twilight and night when whitefish spawn. It is also unknown how long eggs can be identified in stomachs following ingestion, which could limit efforts to quantify egg predation through stomach content analysis. To answer these questions, 144 individuals were given the opportunity to feed on whitefish roe under daylight, twilight, and darkness in controlled conditions. The results showed that stickleback can ingest as many as 100 whitefish eggs under any light conditions, and some individuals even consumed maximum numbers in complete darkness. Furthermore, eggs could be unambiguously identified in the stomach 24 hours after consumption. Whitefish eggs have 28% more energy content than the main diet of sticklebacks (zooplankton) based on bomb-calorimetric measurements, underlining the potential benefits of consuming eggs. Based on experimental results and estimates of stickleback abundance and total egg production, stickleback could potentially consume substantial proportions of the total eggs produced even if relatively few sticklebacks consume eggs. Given the evidence that stickleback can feed on eggs during nighttime spawning and may thereby hamper recruitment, future studies aimed at quantifying actual egg predation and resulting effects on the whitefish population are urgently needed.publishe

Differentiation of two swim bladdered fish species using next generation wideband hydroacoustics

Abstract Monitoring fish populations in large, deep water bodies by conventional capture methodologies requires intensive fishing effort and often causes mass mortality of fish. Thus, it can be difficult to collect sufficient data using capture methods for understanding fine scale community dynamics associated with issues such as climate change or species invasion. Hydroacoustic monitoring is an alternative, less invasive technology that can collect higher resolution data over large temporal and spatial scales. Monitoring multiple species with hydroacoustics, however, usually requires conventional sampling to provide species level information. The ability to identify the species identity of similar-sized individuals using only hydroacoustic data would greatly expand monitoring capabilities and further reduce the need for conventional sampling. In this study, wideband hydroacoustic technology was used in a mesocosm experiment to differentiate between free swimming, similar-sized individuals of two swim-bladdered species: whitefish ( Coregonus wartmanni ) and stickleback ( Gasterosteus aculeatus ). Individual targets were identified in echograms and variation in wideband acoustic responses among individuals, across different orientations, and between species was quantified and visually examined. Random forest classification was then used to classify individual targets of known species identity, and had an accuracy of 73.4% for the testing dataset. The results show that species can be identified with reasonable accuracy using wideband hydroacoustics. It is expected that further mesocosm and field studies will help determine capabilities and limitations for classifying additional species and monitoring fish communities. Hydroacoustic species differentiation may offer novel possibilities for fisheries managers and scientists, marking the next crucial step in non-invasive fish monitoring

High-resolution app data reveal sustained increases in recreational fishing effort in Europe during and after COVID-19 lockdowns

It is well recognized that COVID-19 lockdowns impacted human interactions with natural ecosystems. One example is recreational fishing, which, in developed countries, involves approximately 10% of people. Fishing licence sales and observations at angling locations suggest that recreational fishing effort increased substantially during lockdowns. However, the extent and duration of this increase remain largely unknown. We used four years (2018-2021) of high-resolution data from a personal fish-finder device to explore the impact of COVID-19 lockdowns on angling effort in four European countries. We show that relative device use and angling effort increased 1.2-3.8-fold during March-May 2020 and generally remained elevated even at the end of 2021. Fishing during the first lockdown also became more frequent on weekdays. Statistical models explained 50-70% of the variation, suggesting that device use and angling effort were relatively consistent and predictable through space and time. Our study demonstrates that recreational fishing behaviour can change substantially and rapidly in response to societal shifts, with profound ecological, human well-being and economic implications. We also show the potential of angler devices and smartphone applications for high-resolution fishing effort analysis and encourage more extensive science and industry collaborations to take advantage of this information

The distribution and spread of quagga mussels in perialpine lakes north of the Alps

The dreissenids, quagga mussel Dreissena bugensis and zebra mussel D. polymorpha, are invasive freshwater mussels in Europe and North America. These species strongly impact aquatic ecosystems, such as the food web through their high abundance and filtration rate. They spread quickly within and between waterbodies, and have the ability to colonize various substrates and depths. The zebra mussel invaded and established in Swiss lakes in the 1960s, whereas the quagga mussel was not detected until 2014. We collected all available data from cantonal as well as local authorities and other institutions to describe the colonization pattern of quagga mussels in perialpine lakes north of the Alps. We also collected data regarding the distribution of larval stages of the mussels, the so-called veliger larvae. We observed that in lakes colonized by the quagga mussel, veligers are present the whole year round, whereas they are absent in winter in lakes with only zebra mussels. Additionally, we present detailed information about the invasion and colonization pattern of quagga mussels in Lake Constance. Quagga mussels colonized the lakeshore within a few years (~ 2016–2018), outcompeted zebra mussels, and have reached densities > 5000 ind. m-2 in the littoral zone, even at 80 m densities above 1000 ind. m-2 were found at some locations. At the end of the article, we discussed possibilities on how the spread of quagga mussels within and among northern perialpine lakes should be monitored and prevented in the future.publishe

The distribution and spread of quagga mussels in perialpine lakes north of the Alps

The dreissenids, quagga mussel Dreissena bugensis and zebra mussel D. polymorpha, are invasive freshwater mussels in Europe and North America. These species strongly impact aquatic ecosystems, such as the food web through their high abundance and filtration rate. They spread quickly within and between waterbodies, and have the ability to colonize various substrates and depths. The zebra mussel invaded and established in Swiss lakes in the 1960s, whereas the quagga mussel was not detected until 2014. We collected all available data from cantonal as well as local authorities and other institutions to describe the colonization pattern of quagga mussels in perialpine lakes north of the Alps. We also collected data regarding the distribution of larval stages of the mussels, the so-called veliger larvae. We observed that in lakes colonized by the quagga mussel, veligers are present the whole year round, whereas they are absent in winter in lakes with only zebra mussels. Additionally, we present detailed information about the invasion and colonization pattern of quagga mussels in Lake Constance. Quagga mussels colonized the lakeshore within a few years (~ 2016–2018), outcompeted zebra mussels, and have reached densities > 5000 ind. m-2 in the littoral zone, even at 80 m densities above 1000 ind. m-2 were found at some locations. At the end of the article, we discussed possibilities on how the spread of quagga mussels within and among northern perialpine lakes should be monitored and prevented in the future.ISSN:1818-5487ISSN:1798-654

The distribution and spread of quagga mussels in perialpine lakes north of the Alps

The dreissenids, quagga mussel Dreissena bugensis and zebra mussel D. polymorpha, are invasive freshwater mussels in Europe and North America. These species strongly impact aquatic ecosystems, such as the food web through their high abundance and filtration rate. They spread quickly within and between waterbodies, and have the ability to colonize various substrates and depths. The zebra mussel invaded and established in Swiss lakes in the 1960s, whereas the quagga mussel was not detected until 2014. We collected all available data from cantonal as well as local authorities and other institutions to describe the colonization pattern of quagga mussels in perialpine lakes north of the Alps. We also collected data regarding the distribution of larval stages of the mussels, the so-called veliger larvae. We observed that in lakes colonized by the quagga mussel, veligers are present the whole year round, whereas they are absent in winter in lakes with only zebra mussels. Additionally, we present detailed information about the invasion and colonization pattern of quagga mussels in Lake Constance. Quagga mussels colonized the lakeshore within a few years (~ 2016–2018), outcompeted zebra mussels, and have reached densities > 5000 ind. m-2 in the littoral zone, even at 80 m densities above 1000 ind. m-2 were found at some locations. At the end of the article, we discussed possibilities on how the spread of quagga mussels within and among northern perialpine lakes should be monitored and prevented in the future.ISSN:1818-5487ISSN:1798-654