Differential growth of the barnacle Notobalanus flosculus (Archaeobalanidae) onto artificial and live substrates in the Beagle Channel, Argentina

In the Beagle Channel, southern South America (ca. 55°S 67°W), about 20% of false king crabs (Paralomis granulosa) >80 mm carapace length are fouled with the barnacle Notobalanus flosculus. To evaluate differences in growth rates of barnacles attached to artificial and live substrates, clay tiles were anchored as collectors to the bottom at two different sites in the Beagle Channel in September 1996: in Ushuaia harbour (low currents and high levels of suspended matter) and around the Bridges Islands (strong currents and low level of suspended matter). Another set of collectors was deployed at the same sites in October 1998 to collect barnacles for histological studies. Tiles were removed from each place, approximately, on a monthly basis. Carapaces of P. granulosa with the epizoic N. flosculus were sampled between November 1996 and 1997, and between March 1998 and September 1999, to study sexual maturation of barnacles. Growth of barnacles was compared between the collectors and P. granulosa carapaces following a qualitative approach. A sexual maturity scale was defined, based on the stage of development of the female reproductive apparatus of N. flosculus. Growth rate of barnacles was highest in the harbour, intermediate on P. granulosa, and lowest around the Bridges Islands. Presence of oocytes was registered only in epizoic barnacles, suggesting that at least a proportion of these individuals is able to spawn on the carapaces. The potential advantages of settling on a living substrate, namely increased availability of food particles and decreased predation risks are discussed. © Springer-Verlag and AWI 2005.Fil:Venerus, L.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Calcagno, J.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Lovrich, G.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Nahabedian, D.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

First Assessment of the Impacts of the COVID-19 Pandemic on Global Marine Recreational Fisheries

This work is the result of an international research effort to determine the main impacts of the COVID-19 pandemic on marine recreational fishing. Changes were assessed on (1) access to fishing, derived from lockdowns and other mobility restrictions; (2) ecosystems, because of alterations in fishing intensity and human presence; (3) the blue economy, derived from alterations in the investments and expenses of the fishers; and (4) society, in relation to variations in fishers’ health and well-being. For this, a consultation with experts from 16 countries was carried out, as well as an international online survey aimed at recreational fishers, that included specific questions designed to capture fishers’ heterogeneity in relation to behavior, skills and know-how, and vital involvement. Fishers’ participation in the online survey (5,998 recreational fishers in 15 countries) was promoted through a marketing campaign. The sensitivity of the fishers’ clustering procedure, based on the captured heterogeneity, was evaluated by SIMPER analysis and by generalized linear models. Results from the expert consultation highlighted a worldwide reduction in marine recreational fishing activity. Lower human-driven pressures are expected to generate some benefits for marine ecosystems. However, experts also identified high negative impacts on the blue economy, as well as on fisher health and well-being because of the loss of recreational fishing opportunities. Most (98%) of the fishers who participated in the online survey were identified as advanced, showing a much higher degree of commitment to recreational fishing than basic fishers (2%). Advanced fishers were, in general, more pessimistic about the impacts of COVID-19, reporting higher reductions in physical activity and fish consumption, as well as poorer quality of night rest, foul mood, and raised more concerns about their health status. Controlled and safe access to marine recreational fisheries during pandemics would provide benefits to the health and well-being of people and reduce negative socioeconomic impacts, especially for vulnerable social groups.Versión del edito

Differential growth of the barnacle Notobalanus flosculus (Archaeobalanidae) onto artificial and live substrates in the Beagle Channel, Argentina

In the Beagle Channel, southern South America (ca. 55°S 67°W), about 20% of false king crabs (Paralomis granulosa) >80 mm carapace length are fouled with the barnacle Notobalanus flosculus. To evaluate differences in growth rates of barnacles attached to artificial and live substrates, clay tiles were anchored as collectors to the bottom at two different sites in the Beagle Channel in September 1996: in Ushuaia harbour (low currents and high levels of suspended matter) and around the Bridges Islands (strong currents and low level of suspended matter). Another set of collectors was deployed at the same sites in October 1998 to collect barnacles for histological studies. Tiles were removed from each place, approximately, on a monthly basis. Carapaces of P. granulosa with the epizoic N. flosculus were sampled between November 1996 and 1997, and between March 1998 and September 1999, to study sexual maturation of barnacles. Growth of barnacles was compared between the collectors and P. granulosa carapaces following a qualitative approach. A sexual maturity scale was defined, based on the stage of development of the female reproductive apparatus of N. flosculus. Growth rate of barnacles was highest in the harbour, intermediate on P. granulosa, and lowest around the Bridges Islands. Presence of oocytes was registered only in epizoic barnacles, suggesting that at least a proportion of these individuals is able to spawn on the carapaces. The potential advantages of settling on a living substrate, namely increased availability of food particles and decreased predation risks are discussed. © Springer-Verlag and AWI 2005.Fil:Venerus, L.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Calcagno, J.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Lovrich, G.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Nahabedian, D.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Acoustic telemetry and accelerometers: a field comparison of different proxies for activity in the marine environment

Different proxies for activity are used in the field of acoustic telemetry, a leading technology for the study of behaviour in the aquatic environment. Acoustic telemetry poses some shortcomings that may condition data interpretation. Here, we assessed some approaches commonly used to infer activity from acoustic telemetry data using acceleration biologgers as a benchmark. Specifically, we assessed (1) the performance of internal acceleration transmitters, (2) the consequences of averaging acceleration data into increasing time bins, (3) the occurrence of sampling bias in telemetry data acquisition, and (4) the performance of the number of detections and the depth range as proxies for activity. Despite some constraints of acoustic telemetry, acceleration transmitters had a good performance. Conversely, the number of detections and the depth range did not match well the activity estimates provided by acceleration biologgers. Besides, our results pointed to some issues in models concerning the predictive power of acceleration transmitters (linear predictor) over acceleration biologgers, warned about potential sampling bias associated with data acquisition with acoustic telemetry, and highlighted the relevance of considering inter-individual differences in behavioural studies. Finally, we provided some methodological perspectives that should be considered to plan fieldwork, analyse data, and interpret results on animal activity obtained with acoustic telemetry