SUMMARYAnthropogenic and climate factors increase the frequency of problematic cyanobacterial blooms in freshwater. Among other toxins, some cyanobacteria produce microcystins (MCs), which inhibit phosphatases type 1 and type 2A and provokes oxidative stress. Toxic cyanobacteria affect the growth, survival and reproduction of zooplankton, particularly those from the genus Daphnia, which have a central position in pelagic food webs. However, one possibility to ameliorate effects is to biotransform MC via glutathione S transferase (GST) to a less toxic glutathione conjugate. This process was hypothesised to underlie the ability of Daphnia to withstand MC and to explain the enhanced tolerance of the offspring from mothers exposed to toxic cyanobacteria. Thus we conducted multigenerational experiments with D. magna, exposing the parental generation to MC for 1 or 7days and determining the enzyme-mediated tolerance to MC in their offspring by assessing the acute effect of MC on biotransformation and antioxidant and metabolism enzymes, and through 21day chronic tests on toxicity and growth. Seven days of exposure of the parental generation to MC induced higher activity of GST and malate dehydrogenase in the offspring and enabled them to increment the catalase activity when challenged with MC, whereas 1day of exposure of the parental generation did not. Offspring from non-exposed and 1-day-exposed mothers suffered decreased survival when exposed to MC compared with offspring from 7-day-exposed mothers; survival was correlated with the elevated activity of GST, malate dehydrogenase and catalase, suggesting maternal transfer of activation factors. However, increased survival occurred at the expense of individual growth. These results suggest that transgenerational effects are provoked by MC in D. magna, which may explain the observed acquirement of enhanced tolerance over generations.Key words: microcystin, cyanobacterial toxin, transgenerational effect, Daphnia, zooplankton. THE JOURNAL OF EXPERIMENTAL BIOLOGY 2796 cyanobacteria on Daphnia are reflected by, for example, reduced growth, survival and reproduction (Lampert, 1981; Demott et al., 1991;Hietala et al., 1995;Nogueira et al., 2004;Trubetskova and Haney, 2006; Dao et al., 2010). However, one possible way to reduce toxic effects is to biotransform the toxin MC-LR by conjugation to the tripeptide glutathione (GSH) via the enzyme glutathione S transferase (GST) (Pflugmacher et al., 1998). MCs are conjugated to GSH through the terminal methylene of N-methyldehydroalanine (Kondo, 1992), which is the moiety that binds to the active center of protein phosphatases (MacKintosh, 1995). The resulting conjugate is less toxic (Metcalf et al., 2000) and more hydrophilic, for easier transportation or excretion (Pflugmacher et al., 2001). This MC-LR detoxification process has been described in several aquatic organisms ranging from plants to invertebrates (including Daphnia magna) to fish (Pflugmacher et al., 1998;Wiegand and Pflugmacher, 2005). Three major families of prote...

No abstract

Small scale fisheries are critically important for the provision of food security, livelihoods, and economic development for billions of people. Yet, most of these fisheries appear to not be achieving either fisheries or conservation goals, with respect to creating healthier oceans that support more fish, feed more people and improve livelihoods. Research and practical experience have elucidated many insights into how to improve the performance of small-scale fisheries. Here, we present lessons learned from five case studies of small-scale fisheries in Cuba, Mexico, the Philippines, and Belize. The major lessons that arise from these cases are: (1) participatory processes empower fishers, increase compliance, and support integration of local and scientific knowledge; (2) partnership across sectors improves communication and community buy-in; (3) scientific analysis can lead fishery reform and be directly applicable to co-management structures. These case studies suggest that a fully integrated approach that implements a participatory process to generate a scientific basis for fishery management (e.g., data collection, analysis, design) and to design management measures among stakeholders will increase the probability that small-scale fisheries will implement science-based management and improve their performance.

Cyanobacterial blooms affect aquatic ecosystems due to their capability of producing cyanotoxins (e.g., microcystins, MC; cylindrospermopsin, CYN) and other bioactive compounds. Filter feeding zooplankton are amongst the first organisms affected and research has mainly focused on their interactions with toxic cyanobacteria. We investigated oxidative stress, biotransformation and energetic responses of Daphnia magna after exposure to cyanobacterial extracts and behavioral changes of the animals exposed to living cells of non‐MC and non‐CYN producing strains. Enzyme and energetic responses were measured in time kinetic experiments, using extracts of Microcystis botrys, M. wesenbergii, Aphanizomenon aphanizomenoides, Cylindrospermopsis raciborskii, corresponding to 10 mg DW L−1. In behavioral experiments, D. magna was exposed to living cells of Microcystis aeruginosa, A. aphanizomenoides, Dolichospermum circinalis, C. raciborskii, at the density of 400 000 cells mL−1 using a Daphnia toximeter equipment. Despite not producing MC or CYN, some cyanobacterial extracts caused significant increase of biotransformation enzyme, especially catalase, activities from the exposed D. magna after a longer incubation. Total carbohydrates and glycogen contents were increased but the activity of one of the involved enzymes, the malate dehydrogenase, was not changed. Animals' behavior (e.g., swimming, position within water column) was altered in exposures to cultures of C. raciborskii and D. circinalis. These physiological and behavioral alterations indicate stress, which may impair overall performance of zooplankton at the environmental realistic chronic exposure scenario.

The Upper Gulf of California is a diverse and highly productive ecosystem supporting some of the most important fisheries in Mexico, yet a history of weak fishery management and illegal fishing threatens the area’s biodiversity and undermines human well-being in the communities along its shores. The vaquita (Phocoena sinus) is endemic to these waters and is on the brink of extinction due to incidental entanglement in gillnets used by small-scale fishers. The resurgence of an illegal gillnet fishery for totoaba (Totoaba macdonaldi), whose swim bladders are highly prized in Hong Kong and continental China has exacerbated the decline of vaquita. Vaquita is one of a growing number of cases linking illegal wildlife trade, organized crime, and biodiversity decline. This paper provides a summary of key reflections of a panel of fisheries economists gathered at the ninth forum of the North American Association of Fisheries Economists (NAAFE) to evaluate the policies implemented in the Upper Gulf through an economic lens and updated to reflect more recent developments. The panel found that poor fisheries management, lack of effective enforcement, distant demand for an illegal product, corruption, and few viable economic alternatives were key challenges in addressing vaquita bycatch. The complexity of these problems requires a holistic, multidisciplinary approach, combining top-down (direct regulation) and bottom-up, participatory and incentive-based approaches, to improve governance and enhance community participation and therefore strengthen compliance. Enforcement is a key component of ensuring top-down policies are implemented, and equally crucial are actions to support legal fishermen able to make a good living—with a stake or ownership of their own resources—as important components of policies to address bycatch and also to reduce wildlife trafficking. The situation in the Upper Gulf of California is dire, yet similar threats to other marine mammals and wildlife trafficked species may benefit from the experience of the vaquita.