Submarine groundwater springs are characterized by distinct fish communities

The inflow of terrestrial groundwater into the ocean is increasingly recognized as an important local source of nutrients and pollutants to coastal ecosystems. Although there is evidence of a link between fresh submarine groundwater discharge (SGD)‐derived nutrients and primary producer and primary consumer abundances, the effects of fresh SGD on the productivity of higher trophic levels such as ichthyofaunal communities remain unclear. To further investigate this relationship, we sampled three sites inside a coral reef lagoon in Mauritius: One site entailing six distinct groundwater springs, a site highly influenced by freshwater influx through the springs, and a strictly marine control site. Using remote underwater video surveys, we found that fish abundances were significantly higher at the groundwater springs than at the other two sampling sites.Principal component analyses showed that the springs and the spring‐influenced part of the lagoon were best described by elevated water nutrient loadings, whereas the control site was characterized by higher water salinity and pH. Macroalgae cover was highest at the control site and the springs. Herbivores and invertivores dominated the fish community at the springs, in contrast to generalists at the control site. At the spring‐influenced site, we mainly encountered high coral/turf algae cover and high abundances of associated fish feeding groups (territorial farmers, corallivores). Our results provide evidence of a fresh SGD‐driven relationship between altered hydrography and distinct fish communities with elevated abundances at groundwater springs in a coral reef lagoon. These findings suggest that the management and assessment of secondary consumer productivity in tropical lagoons should take into account the effects of groundwater springs

Feeding behaviours of coral reef fishes in Eilat, Gulf of Aqaba, Red Sea

We used remote underwater stereo-video footage to assess the feeding behaviour of coral reef fishes. Sampling took place on the reef in front of the Inter-University Institute for Marine Sciences (IUI) (29°30'7.0N, 34°55'3.7E) in Eilat (Israel, Gulf of Aqaba) in March 2018. In preparation for the surveys, calibrated stereo-video were set up each consisting of two GoPro (4 x Hero 5 and 2 x Hero 4) cameras mounted on a total of 3 racks (Neuswanger et al., 2016, doi:10.1139/cjfas-2016-0010). For each sampling day, racks were sequentially installed at a depth between 2 to 3 m and set to record continuously. Setting up the cameras was the sole purpose of a dive to minimize the disturbance caused to the site. Sites were chosen based on the criteria that a variety of grazable substratum (not just coral) must be present, as there are a range of micro-habitats within the grazable substrate for herbivorous fishes that require specific categorisation (Green & Bellwood, 2009). Therefore, sites with a mixture of available benthic cover such as live and dead coral, rocks, rubble and sand were generally sought after. Because grazing rates in surgeonfishes are highest during midday, filming was conducted from 11:00 – 17:30 (Fouda and El-Sayed, 1994; Montgomery et al. (1989, doi:10.1016/0022-0981(89)90127-5)). At the beginning of each recording, we placed a 1 x 1 m PVC quadrat with a grid of 100 10 x 10 cm squares. We quantified the live coral cover of each quadrat (in %), and measured fish total length (mm), bite distance (mm), and bite rate (bites per min) only in the delimited area during the entirety of the recorded video footage. The initial 15-min of each video, however, were discarded to allow for fishes to resume normal behaviour after the quadrant has been removed and the divers left the site. For each individual, each bite within the square was recorded from the time of entry to the time of exit and then standardised to obtain bites per minute. We conducted all measurements in VidSync Version 1.661 (Neuswanger et al., 2016; doi:10.1139/cjfas-2016-0010)

Triglyceride concentrations in individual ova of New Zealand Snapper Chrysophrys auratus

Using an innovative analytical approach, we ascertained concentration and composition of triglycerides (TAGs) in individual ova of New Zealand snapper Chrysophrys auratus during three consecutive spawning events in one season. C. auratus broodstock were wild caught several months prior to the commencement of the study and kept in captivity at NIWA's (National Institute of Water and Atmospheric research) Bream Bay aquaculture facility, New Zealand. Thirty-six fish were split equally between two 20 m3 tanks, within the same recirculating system at a water exchange rate of 130 L min−1. Filtered (10 µm) seawater from Bream Bay was allowed to naturally increase to and then maintained at a temperature of 18°C to provide for optimum spawning temperature (Parsons et al., 2014 (doi:10.1080/00288330.2014.892013)). The photoperiod mirrored normal day light hours and fish were hand-fed to satiation daily using a diet of pilchard and squid. Eggs of C. auratus were collected on three separate dates: 21st December 2017, 11th January 2018 and 21st January 2018. Using a net, floating eggs were collected directly from the tanks after spawning and transferred into a large container with the same seawater, dried using a fine plastic mesh (150 μm), sorted and transferred into Eppendorf tubes and stored at -80°C in preparation for subsequent biochemical analysis using Liquid Chromatography-Mass Spectrometry [LC-MS]. Individual eggs were prepared and placed in glass low volume autosampler inserts. 40 μL of LC-MS grade isopropanol (Thermo Fisher NZ Ltd) containing 100 mg L-1 glyceryl tripentadecenoate [TG(15:1(10Z)/15:1(10Z)/15:1(10Z))] [TPD] as internal standard was added to the insert before the eggs were crushed. 10 μL of ultrapure water was then added to the sample and the glass insert was placed into a 1.5 ml Eppendorf tube and centrifuged at 6000 rcf for five minutes. Glass inserts were placed into 1.8 ml amber glass autosampler vials and capped for injection to LC-MS. In total, 147 eggs were prepared for TAG analysis. Triglyceride profiles were acquired using an Agilent 1200 Series liquid chromatograph with an Agilent 6420 triple quadrupole tandem mass spectrometer. An Agilent Poroshell 120 EC-C8 column measuring 150 × 2.1 mm with 2.7 μm packing material was used to separate TAGs and the injection volume was 25 μL. Three mobile phases were used: A) 89.9% ultrapure water and 10% acetonitrile [MeCN] with 0.1% acetic acid, B) MeCN with 0.1% acetic acid and 10mM NH4, and C) 80% IPA, 19.9% MeCN and 0.1% acetic acid with 10mM NH4. All mobile phase solvents and modifiers were mass spectrometry grade. The results were first visualised in TOPPView, an open-source software that is an integrated data visualisation and analysis tool for mass spectrometric data (Sturm and Kohlbacher, 2009 (doi:10.1021/pr900171m)). The m/z and retention times of each TAG peak was recorded and LIPID MAPS online tools for lipid research were used to assign carbon numbers to them, as described in Fahy et al. (2009; doi:10.1194/jlr.R800095-JLR200). TAG peaks were quantified relative to TPD using Agilent MassHunter Quantitative Data Analysis software. Quality was controlled using procedural and carryover blanks

Seasonal growth differences of larval Hyporhamphus picarti (Hemiramphidae) in the Sine Saloum estuary, Senegal

The African halfbeak Hyporhamphus picarti (Hemiramphidae) is one of the most abundant species within the ichthyoplankton community of the Sine Saloum estuary (Senegal). A year‐round occurrence of larvae suggests that the Sine Saloum is an important spawning habitat for this species. Annual fluctuations in water temperature, however, can have severe impacts on the survival probabilities of marine fish larvae. To determine whether temperature has an effect on the growth of H. picarti during its larval development, larval age at length and somatic growth rates were investigated for two contrasting spawning seasons in 2014: February (cold season, 20.8°C) and June (warm season, 26.4°C). In both months H. picarti larvae were sampled at the mouth of the Saloum River using neuston nets. Sagittal otoliths’ increments were counted to estimate the larva age at a given standard length (SL). The age of larvae ranged between 2 and 22 days, with SL of 3.86–21.68 mm, respectively. In order to describe larval age at length during the contrasting spawning seasons, two distinctive Gompertz functions were applied. Accordingly, specimens sampled in June (0.94 ± 0.17 mm per day) exhibited significantly higher somatic growth rates than those sampled in February (0.60 ± 0.06 mm per day). These findings suggest that water temperature is an important factor influencing larval growth in H. picarti. Information concerning the early life stages of H. picarti are scarce and the results of the present study may contribute to a better understanding of the species’ biology and ecology

Data Stewards at the Data Science Center of the University of Bremen: Establishing Domain-Specific Data Stewardship

Three Data Stewards complemented the Research Data Management (RDM) support infrastructure at the University of Bremen in summer 2022. They are located at the Data Science Center (DSC), an interdisciplinary institute founded in 2019 that acts as hub for dataintensive research. The DSC’s main task is to promote excellent research, education and interdisciplinary collaboration in the field of data science. For this purpose, the DSC provides researchers from all disciplines with a wide range of services, such as computing capacities, data literacy trainings, financial support as well as technical and methodological consultancy on the implementation of data science methods (e.g. machine learning). With the three Data Stewards, these services have been extended to include the RDM aspect. The DSC's Data Stewards are discipline-specific experts acting as an interface between researchers and RDM-infrastructure. They offer trainings and consultations along the research data lifecycle following the FAIR principles. Their overarching goal is to reduce the barriers associated with RDM for scientists and to promote a cultural shift towards a FAIRdata-culture. According to their professional backgrounds, they support the following research domains: (1) Social Sciences and Humanities, (2) Natural and Marine Sciences, and (3) Natural and Health Sciences. With their diverse backgrounds and experience, the Data Stewards form a well-balanced team which will be capable of addressing a wide range of RDM-related topics. During the start-up phase, the Data Stewards gained an overview about digital services useful for RDM at the University of Bremen, participated in workshops (e.g. a DIOSI train-the-trainer workshop on European level) and conferences. They presented their services to a wider audience at the DSC’s virtual “Data Science Forum” seminar series. In addition, the Data Stewards have reached out to University of Bremen scientists, research groups, institutes and data repositories to find out first-hand about specific needs but also to identify existing expertise and already established best practice workflows. The Data Stewards provide support for researchers during the preparation of Data Management Plans (DMPs) for funding applications as well as throughout the research process. A service that is likely to become even more prominent in the work of the Data Stewards in the near future. The first discipline-specific trainings offered by the Data Stewards include an Introduction to Research Data Management in Marine Sciences and How to Write Your DMP as a Social Scientist. Sensitised by replication crises in science, especially in the fields of psychology and marine ecology, the Data Stewards have a particular interest in all things open science, especially reproducibility of research results. To raise awareness to this issue and activate the scientific community, they also hosted a Reproducibility Hackathon (ReproHack). The Data Stewards also engage with local networks like the “Research Data Working Group”, which connects initiatives in the fields of RDM and Data Science and is organised under the umbrella of the U Bremen Research Alliance (UBRA) – a cooperation network of the University of Bremen and twelve state-financed non-university research institutes. At the same time, UBRA member institutions are involved in eight of 19 consortia of the first two funding rounds of the German National Research Data Infrastructure (Nationale Forschungsdateninfrastruktur, NFDI) and therefore provide valuable networking opportunities for the Data Stewards. Another important initiative is the “Data Stewardship Network”, where UBRA scientists interested in sustainable and collaborative RDM have the opportunity to exchange with colleagues on a regular basis. In addition, the Data Stewards work closely together with the central “Research Services” unit of the University of Bremen, which provides general support on DMPs, and the library with its expertise in open-access publishing and data archiving. Links with these already existing networks and support infrastructures will not only be important for joint activities and synergies at the operational level, but also to benefit from collegial advice across disciplines. The DSC’s Data Stewards are only at the beginning of their work. For the future, they plan to advance their activities in fields of data-lifecycle support, RDM policies, best practices, data repository selection, DMP writing, and data literacy training. In order to provide the best possible support to researchers in the aforementioned disciplines and beyond, they will continue to refine their RDM services in collaboration with existing RDM structures at the University of Bremen and UBRA. The aim is to increase the visibility of their services, activate researchers, as well as to pool and expand RDM resources. Three Data Stewards complemented the Research Data Management (RDM) support infrastructure at the University of Bremen in summer 2022. They are located at the Data Science Center (DSC), an interdisciplinary institute founded in 2019 that acts as hub for dataintensive research. The DSC’s main task is to promote excellent research, education and interdisciplinary collaboration in the field of data science. For this purpose, the DSC provides researchers from all disciplines with a wide range of services, such as computing capacities, data literacy trainings, financial support as well as technical and methodological consultancy on the implementation of data science methods (e.g. machine learning). With the three Data Stewards, these services have been extended to include the RDM aspect. The DSC's Data Stewards are discipline-specific experts acting as an interface between researchers and RDM-infrastructure. They offer trainings and consultations along the research data lifecycle following the FAIR principles. Their overarching goal is to reduce the barriers associated with RDM for scientists and to promote a cultural shift towards a FAIRdata-culture. According to their professional backgrounds, they support the following research domains: (1) Social Sciences and Humanities, (2) Natural and Marine Sciences, and (3) Natural and Health Sciences. With their diverse backgrounds and experience, the Data Stewards form a well-balanced team which will be capable of addressing a wide range of RDM-related topics. During the start-up phase, the Data Stewards gained an overview about digital services useful for RDM at the University of Bremen, participated in workshops (e.g. a DIOSI train-the-trainer workshop on European level) and conferences. They presented their services to a wider audience at the DSC’s virtual “Data Science Forum” seminar series. In addition, the Data Stewards have reached out to University of Bremen scientists, research groups, institutes and data repositories to find out first-hand about specific needs but also to identify existing expertise and already established best practice workflows. The Data Stewards provide support for researchers during the preparation of Data Management Plans (DMPs) for funding applications as well as throughout the research process. A service that is likely to become even more prominent in the work of the Data Stewards in the near future. The first discipline-specific trainings offered by the Data Stewards include an Introduction to Research Data Management in Marine Sciences and How to Write Your DMP as a Social Scientist. Sensitised by replication crises in science, especially in the fields of psychology and marine ecology, the Data Stewards have a particular interest in all things open science, especially reproducibility of research results. To raise awareness to this issue and activate the scientific community, they also hosted a Reproducibility Hackathon (ReproHack). The Data Stewards also engage with local networks like the “Research Data Working Group”, which connects initiatives in the fields of RDM and Data Science and is organised under the umbrella of the U Bremen Research Alliance (UBRA) – a cooperation network of the University of Bremen and twelve state-financed non-university research institutes. At the same time, UBRA member institutions are involved in eight of 19 consortia of the first two funding rounds of the German National Research Data Infrastructure (Nationale Forschungsdateninfrastruktur, NFDI) and therefore provide valuable networking opportunities for the Data Stewards. Another important initiative is the “Data Stewardship Network”, where UBRA scientists interested in sustainable and collaborative RDM have the opportunity to exchange with colleagues on a regular basis. In addition, the Data Stewards work closely together with the central “Research Services” unit of the University of Bremen, which provides general support on DMPs, and the library with its expertise in open-access publishing and data archiving. Links with these already existing networks and support infrastructures will not only be important for joint activities and synergies at the operational level, but also to benefit from collegial advice across disciplines. The DSC’s Data Stewards are only at the beginning of their work. For the future, they plan to advance their activities in fields of data-lifecycle support, RDM policies, best practices, data repository selection, DMP writing, and data literacy training. In order to provide the best possible support to researchers in the aforementioned disciplines and beyond, they will continue to refine their RDM services in collaboration with existing RDM structures at the University of Bremen and UBRA. The aim is to increase the visibility of their services, activate researchers, as well as to pool and expand RDM resources

Spawning energetics and otolith microchemistry provide insights into the stock structure of bonga shad Ethmalosa fimbriata

The gross energy content of spawning batches and the microchemistry of sagittal otoliths in individual female bonga shad Ethmalosa fimbriata were compared between contrasting sampling sites at the Senegalese southern coast and inside the hypersaline Sine Saloum Estuary. Results show that females spawning in the estuary's middle reaches invested almost three times more energy into reproduction (115 ± 65 J g−1 body mass) than their neritic counterparts (39 ± 34 J g−1 body mass). Also, female otolith levels of Ba:Ca, Sr:Ca and Zn:Ca either differed significantly between study sites or could be linked to heterogeneous environmental variables. A quadratic discriminant function analysis provided evidence of segregated spawning populations of E. fimbriata in southern Senegalese waters

Environmental data and fish abundances for Troux aux Biches and Flic en Flac lagoon, Mauritius

Submarine inflow of freshwater from land into the ocean, (fresh) submarine groundwater discharge (SGD), is increasingly recognized as an important source of local nutrient and pollutants influx to coastal ecosystems. Still, very little is known about the effects of SGD on ecosystem functioning. Especially the effects of fresh SGD on the productivity of higher trophic levels such as ichthyofaunal communities remain unclear. We recorded nutrient, radon, and chlorophyll concentrations and benthic composition in two tropical coral reef lagoons on Mauritius, one influenced by distinctive freshwater springs inside the lagoon (Trou aux Biches) and one influenced by freshwater seepage along the shoreline (Flic en Flac). In Trou aux Biches we additionally examined the load of total suspended solids (TSS) in the water column and recorded and analyzed fish abundance and fish community across nine different stations within three different sites (spring, spring influenced, and control) of the lagoon. Depth measurements were taken using a handheld depth sounder (Plastimo Echotest 2) without consideration of benthic cover. Actual depth might be underestimated, especially in coral rich areas of the lagoon. Water samples for nutrient analysis were taken from a depth of 50 cm using a peristaltic pump, filtered, and stored frozen until measurement. Conductivity, Temperature, and Salinity were measured in situ using a handheld probe (WTW Cond 3310, TetraCon325). Water pH was determined in the laboratory using a stationary pH probe (Ohaus Starter 2100). Additionally, water samples were obtained from two oceanic stations offshore the SGD influenced and control part of the lagoon. Nutrient concentrations were determined using standard methods with a discrete analyzer (Systea Easychem Plus) equipped with a 5 cm absorbance reading unit. 222Rn concentrations were determined using an electronic radon detector (RAD 7, Durridge Co.). Benthic coverage was determined using 50 m point intersect transects. All transects were video recorded (Canon Powershot G16) for subsequent analysis. Transect videos were evaluated in the laboratory, recording benthic makeup every 50 cm (n=100) using classifications by English, Wilkinson, & Baker (1997). Total suspended solids (TSS) were sampled in triplicates along 100 m horizontal transects at the springs, the spring influenced part of the lagoon, and at the control site using a 20 µm plankton net. Per transect,a total of 4.91 m³ water (net diameter 25 cm) were filtered. All samples were kept cold in a portable cooling box and frozen at -20°C in the laboratory for subsequent analyses. Frozen TSS samples were defrosted, filtered on a pre-weighted microfiber filter (Whatman GF/F), dried, and weighed again. For Chlorophyll a determination, 1 liter of seawater were taken from a depth of 50cm, filled into a dark PVP bottle and stored in a portable cooling box. In the laboratory the water was filtered onto a microfibre filter (Whatman GF/F), wrapped in tinfoil, stored at -20°C, and shipped to the ZMT in Bremen, Germany. At the laboratory in Bremen, filters where bisected and one half was used to extract Chlorophyll a, using 96% Ethanol. The Chlorophyll a / Ethanol solutions were measured using a fluorometer (TD10AU Flouru, Ex436, Em680). To evaluate fish abundances, GoPro Hero 4 video cameras were weighted and placed at two stations close to the springs, and at three stations at the spring influenced site as well as at the control site. Video data was evaluated using the MaxN/MIN count method (Cappo et al., 2003). Furthermore, videos were used to a) compose a list of all fish species occurring in the lagoon and b) determinate abundances. Diversity was determined using three commonly used metrics, species richness, Shannon's diversity index H', and Pielou evenness J'. Functional groups were used to evaluate changes in the fish community structuring. Groupings are based on similar ecosystem functioning disregarding taxonomic relationships (Bellwood et al., 2004). Fish species were classified into feeding groups indicating feeding behavior and dietary composition (Pratchett et al., 2011). Herbivores and corallivores were further classified using definitions by Green & Bellwood (2009) and Cole et al. (2008), respectively. Commercial species were determined using an open-source dataset provided by the Mauritius Oceanography Institute (Curpen et al., 2013)