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Zooplankton are key ecological components of the marine food web. Currently, laboratory-based methods of zooplankton identification are manual, time-consuming, prone to human error and require expert taxonomists. Therefore, alternative methods are needed. In this study, we describe, implement and compare the performance of six state-of-the-art single-stage deep learning models for automated zooplankton identification. The highest prediction accuracy achieved is 99.50%. The fastest detection speed is 285 images per second, making the models suitable for real-time zooplankton classification. We validate the predictions of the generated models on unseen images. The results demonstrate the capabilities of the latest deep learning models in zooplankton identification. [ABSTRACT FROM AUTHOR]

Great personalities of the Indian subcontinent are associated with our legends, folklore, traditions, rituals and regional songs. Similarly, mountains, trees, cows, fishes, etc. are also linked with the above aspects. Among fishes, these aspects are associated with hilsa or ilisha (Tenualosa ilisha; family Clupeidae). Because hilsa is associated with traditions, scholars have studied this in detail. Hilsa is generally found during the monsoon season between Rivers Ganges and Godavari in India and in Bangladesh. Past several years hilsa has drawn attention because of low production and escalating costs. Therefore, fishermen along the Odisha coast in eastern India require information on hilsa with regard to fishing season and techniques. The catch statistics indicated an increase in the hilsa landings for the past few years. This note discusses information collected from fishing communities of Odisha and compared it with the published literature. It is important to formulate specific guidelines for non-destructive fishing methods for its sustainable management, along with proper scientific assessments to manage the stock by the concerned agencies, which can help in preserving this fish for future generations. [ABSTRACT FROM AUTHOR]

In this study, Soda Lime Glass (SLG) and Stainless Steel (SS316L) substrata coated with Titanium oxide (TiOx) were tested for their efficacy in the laboratory microcosms and in field against micro- and macrofouling. Laboratory microcosm studies were conducted for five days using natural biofilms, single-species diatom (Navicula sp.), and bacterial biofilms, whereas field observations were conducted for 30 days. The TiOx-coating induced change in the mean contact angle of the substratum and rendered SS316L more hydrophilic and SLG hydrophobic, which influenced the Navicula sp. biofilm, and bacterial community structure of the biofilm. Overall, the TiOx-coated SS316L showed minimal microfouling, whereas non-coated SLG exhibited greater efficacy in deterring/preventing macrofouling organisms. Moreover, the reduction in macrofouling could be attributed to high abundance of Actinobacteria. Unraveling the mechanism of action needs future studies emphasizing biochemical processes and pathways. [ABSTRACT FROM AUTHOR]

Identification of marine invertebrate larvae using morphological characters is laborious and complicated by phenotypic plasticity. Balanus amphitrite is a dominant barnacle, important in the context of intertidal ecology and biofouling of manmade structures. Morphological identification of barnacle larval forms in a mixed population is difficult because of their intricacy and similarity in size, shape and developmental stages. We report the development and application of a nucleic acid-based Polymerase Chain Reaction (PCR) method for the specific identification of the barnacle, B. amphitrite, from the heterogeneous zooplankton sample. This method is reliable and accurate thereby overcoming taxonomic ambiguity. Sequence alignment of the 18S rRNA gene region of selected species of barnacles allowed the design of B. amphitrite-specific PCR primers. Assay specificity was evaluated by screening DNA obtained from selected species of barnacles. The oligonucleotide primers used in the study flanked a 1600 bp region within the 18S rRNA gene. The primer is specific and can detect as few as 10 individuals of B. amphitrite larvae spiked in a background of ~186 mg of zooplankton. This technique facilitates accurate identification and the primer can be used as a marker for enumeration of B. amphitrite larvae in the plankton. [ABSTRACT FROM PUBLISHER]

Benthic communities form an important component of the marine food chain. Their occurrence also provides information on the health of the ecosystem. A study was carried out to understand the distribution and abundance of macrobenthos along with sediment characteristics and physicochemical parameters in Visakhapatnam Harbour, a major port along the east coast of India. In all 84 macrobenthic taxa were reported from the port area of which 60 were polychaetes and 24 were other invertebrate taxa. Our observations revealed an increase in the number of polychaete species observed over the last 20 years from this region. An earlier study reported 38 polychaete species in 1975 and a year later the number of polychaete species reported was 12, indicating an increase in the number of polychaete species in the present study by about 150%. The macrobenthic abundance and dominance of species varied with the seasons. Pre-monsoon was dominated by Cirratulus sp., during monsoon tanaids were dominant indicating a seasonal shift in the occurrence and dominance of macrobenthos. During post-monsoon, Cossura coasta was dominant followed by Nephtys dibranchis and amphipods. Sediment characteristics (sand, silt and clay), organic carbon and dissolved oxygen were the important factors influencing the abundance and species diversity. The abundance of macrobenthic forms also varied with inner and outer harbour region. Higher species diversity was observed in the outer harbour suggesting the outer harbour has semi-polluted conditions such as higher dissolved oxygen (DO) and salinity, low nutrients (nitrite, nitrate and silicate) and low organic carbon in the sediment. [ABSTRACT FROM PUBLISHER]

The effect of Irgarol 1051 on the biofilm-forming diatom, Amphora coffeaformis, and on natural biofilm (NBF) was assessed. A reduction in the number of A. coffeaformis cells within a biofilm was observed after treatment with Irgarol 1051, confirming its role as an inhibitor of photosynthetic activity. The impact of this compound on the development of nauplii of Balanus amphitrite was evaluated through its impact on Chaetoceros calcitrans, which was provided as food for the larvae. A reduction in the number of cells of C. calcitrans was observed when treated with Irgarol 1051. When larvae of B. amphitrite were reared using C. calcitrans in the presence of Irgarol 1051, their mortality increased with an increase in the concentration of Irgarol 1051 (13% at 1 µg l-1 to 40% at 1000 µg l-1) compared with the control (6%). Nauplii reared in the presence of Irgarol 1051 developed more slowly (6-7 days) compared with control larvae (4-5 days). Cyprid bioassay results indicated an increase in percentage metamorphosis (76%) when NBFs were treated with the highest concentration of Irgarol 1051, compared with untreated biofilm (28%). The enhanced rate of metamorphosis appeared to be related to an increase in bacterial numbers in the biofilm, which may have been due to lysis of diatoms caused by Irgarol 1051. A. coffeaformis biofilms grown in the presence of antibiotics showed a significant reduction in cell numbers, which on further treatment with Irgarol 1051 showed an increase in cell numbers. Thus, it can be hypothesised that A. coffeaformis cells that were subjected to stress twice may have expressed resistant genes. Furthermore, if plasmids are present in the biofilms, they may enhance transfer to the surviving cells making them more resistant to hostile conditions. [ABSTRACT FROM AUTHOR]