Prevalence of Argulus indicus, histopathology and hematological properties of infected wild fish in Lake Towuti, Indonesia

Amriana, Sari DK, Sriwulan, Anshary H. 2021. Prevalence of Argulus indicus, histopathology and hematological properties of infected wild fish in Lake Towuti, Indonesia. Biodiversitas 22: 3578-3584. Parasites are disease agents that can threaten the health and survival of wild fish as individuals and at a population level. This study aimed to improve knowledge on the prevalence of Argulus indicus, infestation rates and the pathological effects of parasite infestation on hosts as well as hematological properties of infected fish. This study can inform future studies on the prevention and control of the cases of Argulus indicus infestation. Fish from Lake Towuti (20 45? 0? S, 1210 30? 0? E) were caught from February to May 2019 using traps and gill nets. The total of 373 specimens obtained comprised 102 climbing perch (Anabas testudineus), 74 three-spot cichlids (Cichlasoma trimaculatum), 84 Nile tilapia (Oreochromis niloticus), and 113 striped snakeheads (Channa striata). The prevalence, mean intensity and abundance of A. indicus were highest in C. striata with a prevalence of 81%, mean intensity of 5.17 parasites/fish and abundance of 4.06 parasites/fish. The lowest parasite infection level was seen in C. trimaculatum with a prevalence of 4.1%, mean intensity 1.66 and mean abundance of 0.06. Histological analysis showed inflammatory responses in the skin of snakeheads (hemorrhage, increased spread of melanomacrophage and leukocyte cells), melanomacrophage and the spread of leukocyte cells were observed in climbing perch. In contrast, melanomacrophage was often observed in tilapia and trimac cichlid. Blood imaging analysis showed significant differences (P <0.05) in the number of leukocytes and percentage of monocyte cells between uninfested fish and those infested with A. indicus.

Ichthyofauna of Endemic Fish in Towuti Lake, Luwu Timur Regency, South Sulawesi, Indonesia

Aims: The aims of this study to determine the biodiversity of endemic fish in Lake Towuti, Luwu Timur Regency South Sulawesi, Indonesia. Study Design: The research was conducted by survey Place and Duration of Study: The research was carried out in February until March 2021 in Tanjung Timbala; Tanjung Lengkobutanga; Tanjung Bakara; Tanjung Saone and. Tanjung Tominanga at Lake Towuti, Luwu Timur Regency South Sulawesi, Indonesia. Methodology: Fish samples were carried out every week using a trap net for 8 weeks. Fish samples obtained from each station were separated according to species. Fish samples were preserved with 4% formalin and then immersed in 70% alcohol before species identification was conducted. Data analysis in this research used descriptive statistics. Results: The endemic fish species was found is telamtherina bonti Telmatherina bonti, Telmatherina celebensis, Paratherina striata, Tominanga sanguicauda, Tominanga aurea Oryzias profundicola, Oryzias matanensis, Oryzias marmoratus, Mugilogobius hitam, Glossogobius flavipinnis, Glossogobius matanensis and Dermogenys megarhamphus. The percentage of endemic fish caught at each station on Lake Towuti was different. The water quality parameters obtained are as follows Temperature: 26.40⁰C-30.30⁰C, pH: 6.35-9.03, dissolved oxygen (DO):6.25-8.95 mg/L and NO3-N: 0.023-0.066 mg/L.This water quality were suitable for the survival and growth of endemic fish. Conclusion: Endemic fish families were obtained such as Telmatheridae, Adrianichthyidae, Gobiidae and Hemiramphidae and a total of twelve endemic fish species were found in this study. The number of endemic fish was found to be different at the station. Water quality parameters play an important role in the distribution and existence of endemic fish in Lake Towuti.

Organic matter mineralization in modern and ancient ferruginous sediments

Deposition of ferruginous sediment was widespread during the Archaean and Proterozoic Eons, playing an important role in global biogeochemical cycling. Knowledge of organic matter mineralization in such sediment, however, remains mostly conceptual, as modern ferruginous analogs are largely unstudied. Here we show that in sediment of ferruginous Lake Towuti, Indonesia, methanogenesis dominates organic matter mineralization despite highly abundant reactive ferric iron phases like goethite that persist throughout the sediment. Ferric iron can thus be buried over geologic timescales even in the presence of labile organic carbon. Coexistence of ferric iron with millimolar concentrations of methane further demonstrates lack of iron-dependent methane oxidation. With negligible methane oxidation, methane diffuses from the sediment into overlying waters where it can be oxidized with oxygen or escape to the atmosphere. In low-oxygen ferruginous Archaean and Proterozoic oceans, therefore, sedimentary methane production was likely favored with strong potential to influence Earth’s early climate.

Unlocking the power of lake multiproxy analyses by understanding subsurface biosphere processes

&lt;p&gt;Lake sediments bear valuable information allowing multidisciplinary research to address paleoclimatic and paleoenvironmental reconstructions at regional to global scales. Sedimentological, geochemical, paleontological and biological tools are commonly used to tackle these questions, which are generally driven by a set of intricated parameters. Among them, the importance of biogeochemical cycling is largely acknowledged in the lake (paleo-) water columns and has been at the heart of most paleolimnological studies. The way these signals are transferred to lake sediments has largely been studied. However, microbial communities - the principal actors in the biogeochemical cycling framework - keep being active in the sediment, and continue to influence the preservation and retention of organic and inorganic matter while buried. Gathered within the &amp;#8220;early diagenesis&amp;#8221; black box, these processes, once qualified, can help better interpret the proxies they may influence, and even constitute new ones. Within this work, we provide examples showing that the integration of studies of the subsurface biosphere within geo- and paleo-limnology investigations can help unlock or secure the potential of multiproxy analysis for reconstructing the paleoenvironments, paleoclimates and paleo-ecology of lake basins. The use of now well-developed OMICS methods, through the analysis of environmental and/or ancient DNA and lipids in particular has been coupled to mineralogical, isotopic and magnetic information in the Dead Sea (Levant) to demonstrate the differential preservation of mineralogic and sedimentologic signals along the last two glacial-interglacial cycles (Thomas et al., 2015, 2016; Ebert et al., 2018). Similar signals have been unlocked in Lake Towuti (Indonesia) and in Laguna Potrok Aike (Argentina) (Vuillemin et al., 2015, 2017). In Lake Ohrid (North Macedonia/Albania), environmental DNA has provided limited inputs on that perspective (Thomas et al., 2020), but has shown that ancient/fossil DNA could provide valuable information regarding the lake primary productivity and the status of its watershed land-cover. Integrating OMICS methods to tackle the identity and activity of the ancient and modern subsurface biosphere of lakes therefore holds an immense potential not only for microbiology investigations, but also for paleoclimatic and paleoenvironmental reconstructions.&lt;/p&gt;&lt;p&gt;Ebert et al. (2018) Overwriting of sedimentary magnetism by bacterially mediated mineral alteration. Geology &lt;strong&gt;46&lt;/strong&gt;, 2&amp;#8211;5.&lt;/p&gt;&lt;p&gt;Thomas et al. (2016) Microbial sedimentary imprint on the deep Dead Sea sediment. The Depositional Record 1&amp;#8211;21.&lt;/p&gt;&lt;p&gt;Thomas et al. (2020) Weak influence of paleoenvironmental conditions on the subsurface biosphere of lake ohrid over the last 515 ka. Microorganisms &lt;strong&gt;8&lt;/strong&gt;, 1&amp;#8211;20.&lt;/p&gt;&lt;p&gt;Thomas et al. (2015) Impact of paleoclimate on the distribution of microbial communities in the subsurface sediment of the Dead Sea. Geobiology &lt;strong&gt;13&lt;/strong&gt;, 546&amp;#8211;561.&lt;/p&gt;&lt;p&gt;Vuillemin et al. (2015) Recording of climate and diagenesis through fossil pigments and sedimentary DNA at Laguna Potrok Aike, Argentina. Biogeosciences Discussions &lt;strong&gt;12&lt;/strong&gt;, 18345&amp;#8211;18388.&lt;/p&gt;&lt;p&gt;Vuillemin et al. (2017) Preservation and Significance of Extracellular DNA in Ferruginous Sediments from Lake Towuti , Indonesia. Frontiers in Microbiology &lt;strong&gt;8&lt;/strong&gt;, 1&amp;#8211;15.&lt;/p&gt;

A 1 Ma record of climate-induced vegetation changes using sed aDNA and pollen in a biodiversity hotspot: Lake Towuti, Sulawesi, Indonesia

&lt;p&gt;Several studies have shown that ancient plant-derived DNA can be extracted and sequenced from lake sediments and complement the analysis of fossil pollen in reconstructing past vegetation responses to climate variability and anthropogenic perturbations. The majority of such studies have been performed on Holocene lakes located in cooler higher latitude regions whereas similar studies from tropical lakes are limited. Here, we report a ~1 Ma record of vegetation changes in tropical Lake Towuti (Sulawesi, Indonesia) through parallel pollen and sedimentary ancient DNA (sed aDNA) analysis. Lake Towuti is located in a vegetation biodiversity hotspot and in the centre of the Indo Pacific Warm Pool (IPWP), which comprises the world&amp;#8217;s warmest oceanic waters and influences globally important climate systems. In the context of global change, the surface area of the IPWP is rapidly expanding. Lake Towuti is of particular interest since it provides a unique opportunity to obtain a long-term record of IPWP-controlled climate-ecosystem interactions and ecosystem resilience. Stratigraphic analysis of fossil pollen vs. sequencing of preserved chloroplast DNA (cpDNA) signatures (i.e., trnL-P6) both revealed that Lake Towuti experienced significant vegetation changes during the transition from a landscape initially characterized by active river channels, shallow lakes and swamps into a permanent lake ~1 Ma ago. Both proxies marked a predominance of trees or shrubs during most of Lake Towuti&amp;#8217;s history, but the trnL-P6 barcoding approach revealed a much higher relative abundance of remote montane conifers, which likely have produced large amounts of chloroplast-rich airborne pollen that were subsequently buried in the sedimentary record. The pollen record showed a higher relative abundance of evergreen tropical forest vegetation, whereas the trnL-P6 record revealed a higher relative abundance of predominantly wetland herbs that must have entered the lake from the local catchment in the form of chloroplast-rich litter. Furthermore, the sedimentary record was rich in presumably wind-derived chloroplast-lacking fern spores, while fern trnL-P6 was only sporadically detected. Only through trnL-P6 barcoding, fern-derived biomass in the sedimentary record could be identified as Schizaeaceae, which is a primitive tropical grass-like fern family often associated with swampy or moist soils. Unlike pollen, trnL-P6 could identify grasses at clade and subfamily levels and confirmed that the majority of grasses in the area represented wet climate C3 grasses or those that can switch between C3 and C4 carbon fixation pathways, whereas grasses that can only perform C4 carbon fixation, indicative of dry climate conditions, were not detected. At least for sediments deposited prior to the Last Glacial Maximum, neither pollen nor trnL-P6 revealed significant vegetation changes between alternating layers of lacustrine green and red sideritic clays thought to have been deposited during orbitally controlled wetter vs. drier periods. These preliminary results suggest that vegetation in this tropical biodiversity hotspot may be relatively resilient to long-term variations in IPWP hydrology.&lt;/p&gt;

Seismic event stratigraphy of tectonic Lake Towuti, Sulawesi, Indonesia: a 15 kyrs record of seismo-turbidites

&lt;p&gt;Located at the triple junction of the Pacific, Eurasian and Sunda plates, the island of Sulawesi in Indonesia is one of the most tectonically active places on Earth. This is highlighted by the recurrence of devastating earthquakes such as the 2018 Mw 7.5 earthquake that destroyed the city of Palu and caused several thousand deaths in central Sulawesi. The majority of large magnitude earthquakes on Sulawesi are related to stress release along major strike-slip faults such as the Palu-Koro fault and its southern extensions the Matano and Lawanopo faults. To date, information on the frequency and magnitude of major events on these faults is limited to instrumental records, whereas information from historical sources and natural archives is completely lacking. Considering the increase in population density and its extension into distant areas, it is important to better quantify the seismic hazard. Therefore, a systemic catalogue of past earthquakes is essential for the understanding of tectonic dynamics of the area.&lt;/p&gt;&lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; Lake Towuti, situated in Eastern Sulawesi, is a key site to study the paleoseismology on the island. The lake lies close to the Matano strike-slip fault and is hence an ideal archive for past earthquakes that have occurred in the surrounding area. Moreover, its morphology allows a temporally continuous sedimentary succession. The large and deep central basins of the lake preserve the deposits linked to seismic activity. We combine high-resolution Chirp seismic data with sedimentary analyses of sediment piston cores to assess the recurrence of major earthquakes (Mw &gt; 6) in the area, which are expressed by earthquake-triggered Mass Wasting Deposits (MWD). Five major seismic-stratigraphic units are identified in the upper 200 milliseconds TWT and show different depositional mechanisms. MWD&amp;#8217;s and associated seismoturbidites can be easily distinguished in seismic data and are well preserved in the cored sedimentary successions in the topmost Unit 1.1. Chronologically Unit 1.1 covers the last 15 kyrs and enables the establishment of an event chronostratigraphy for Lake Towuti&amp;#8217;s recent past. The most recent MWD likely corresponds to an AD 1924 Mw 6.5 earthquake, which was recorded to the south of Lake Towuti. In addition, 11 seismoturbidites have been observed in the Late Glacial to Holocene (~15 kyrs) sediment succession. These results tentatively suggest an average recurrence of major events every 1300 to 1400 years.&lt;/p&gt;