Flying fishes (Exocoetidae) are commonly found in the epipelagic zone and play an important role in Taiwan in maintaining the stability of the marine ecosystem, local culture and coastal fisheries. However, little is known about their biology and life history, even though several species are of important commercial value in western Pacific countries. Overexploitation of one of the dominant species, the bony flying fish Hirundichthys oxycephalus, is a critical issue in the fishery management and resource assessment of this species. In the present study, H. oxycephalus eggs were harvested off northeastern Taiwan, while adult fish were collected mainly off the southeastern coast of Taiwan. We validated the daily periodicities of the growth increments in 3 otolith pairs based on the successive otolith examination of fish reared in the laboratory from fertilized eggs. The asteriscus was determined to be the most suitable otolith for age determination of the fish. Age (in days) was calculated by counting the number of growth increments on the mounted otolith and adding 11. By using a growth coefficient of 0.0075 d−1, the asymptotic length of these fish was estimated to be 253.86 mm. Back-calculated hatching dates indicated that an occurrence of the summer spawning cohort coincided with the known egg-fishing season off the northeastern coast. On the other hand, the source of the adult fishery off the southeastern coast originated from a new winter spawning cohort. The cohort dynamics of this species were found to be more complicated than previously thought. Our findings could be added to the information already known about the reproductive ecology of H. oxycephalus and used to improve the fisheries management of these fish.

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 15:187-194 (2012) - DOI: https://doi.org/10.3354/ab00430 Fish are not safe from great cormorants in turbid water David Grémillet1,2, Theodoros Nazirides3, Harris Nikolaou4, Alain J. Crivelli5,* 1Centre d’Ecologie Fonctionnelle et Evolutive, UMR 5175 du CNRS, 1919 Route de Mende, 34293 Montpellier cedex 5, France 2Percy FitzPatrick Institute of African Ornithology, DST/NRF Centre of Excellence at the University of Cape Town, Rondebosch 7701, South Africa 3Vironia, N Petritsi 62043, Greece 4Society for the Protection of Prespa, Prespa, Agios germanos 530 77, Greece 5Station Biologique de la Tour du Valat, 13200 Le Sambuc, France *Corresponding author. Email: a.crivelli@tourduvalat.org ABSTRACT: Great cormorant populations have shown near-exponential increase in Western Europe over recent decades, generating wildlife management conflicts across the region. It is essential to detail the foraging strategies of this piscivorous predator to understand the functional mechanisms determining its actual impact upon freshwater fisheries. Great cormorants have been shown to be highly efficient predators, yet their underwater vision is limited in turbid water. We therefore tested the hypothesis that the predatory performance of great cormorants will be lower in turbid than in clear water. We used parallel data sets on water turbidity, great cormorant diet, great cormorant population size, fish biomass and fish-cormorant co-occurrence collected over 3 decades, with a focus on 1997 and 1998, in 2 Macedonian lake systems with contrasting features. In one lake system, water turbidity was lower, fish abundance was also lower, and the local great cormorant population did not increase markedly in size. Local populations of Alburnus belvica, which is the preferred prey of great cormorants in this region, increased over the study period. In the second lake system, water turbidity was higher, fish abundance was also higher, and the local great cormorant population has increased exponentially since the 1980s. Along the highly turbid affluent of this lake, great cormorants foraged en masse at the time of highest fish abundance, and local fish biomass decreased over the study period. Overall, our data strongly suggest that great cormorants remain highly efficient fish predators even in the most turbid water. We propose that they switch from visual to tactile cues to maintain high foraging efficiency when diving in water above a certain turbidity threshold. KEY WORDS: Cormorant · CPUE · Piscivorous bird · Predation · Secchi depth · Avian vision · Wildlife conflict Full text in pdf format PreviousCite this article as: Grémillet D, Nazirides T, Nikolaou H, Crivelli AJ (2012) Fish are not safe from great cormorants in turbid water. Aquat Biol 15:187-194. https://doi.org/10.3354/ab00430 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 15, No. 2. Online publication date: May 15, 2012 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2012 Inter-Research.

European eel Anguilla anguilla migratory behaviour during continental life is still unclear due to the multiplicity of aquatic environments colonised by the species. In the Camargue area (NW Mediterranean), eel colonisation of the Fumemorte canal, a freshwater habitat that com- municates only with a vast brackish ecosystem (the Vaccares lagoon), offers a rare opportunity to test for freshwater habitat residence during continental life. To this end, both laser ablation inductively coupled plasma mass spectrometry and electron probe micro-analysis were used to measure chronological variations of strontium concentrations (Sr:Ca) in the otoliths of 58 silver eels captured in the canal between 1997 and 2007. Comparing mean Sr:Ca ratios measured on oto- lith edges with the 2 analytical methods indicated that they provide comparable measurement accuracies. Linear discriminant analysis (LDA), based on the otolith Sr:Ca values corresponding to the initial entrance of the fish into the brackish ecosystem and their final capture in the freshwater canal, allowed successful discrimination of the 2 habitats and reconstruction of migratory history for all individuals. Six different migratory behaviours were identified. Eels that entered the fresh- water canal did so either directly (67%) or after 1 to 2 yr spent in the lagoon (33%), with a subse- quent majority of freshwater residents (55%) until their silvering. These results indicate the value of LDA for reconstructing habitat use during continental life using Sr:Ca ratios. They confirm the occurrence of freshwater residence during continental life in European eels, even in Mediter- ranean continental areas where brackish environments are predominant. This observed seden- tary behaviour has implications for eel population management and conservation.

In the present study, we examined the variation in composition and biomass of epi- phyton growing on the bulrush Schoenoplectus californicus in a pampean lake that passed through a turbid- and a clear-water period within an annual cycle. Monthly sampling was per- formed year-round at the center and periphery of a bulrush stand. We measured the physicochem- ical parameters in the water column using standardized field and laboratory methods. The epiphy- ton was sampled by sectioning bulrush stems into segments for pigment analysis, abundance measurements, and biovolume quantification. Two different types of communities were observed during the annual cycle. In the turbid-water period, epiphyton biomass and diversity remained low despite sufficient levels of phosphates. An abrupt increase in epiphyton biomass, along with structural changes in the community, occurred after an improvement in water transparency, sug- gesting that the epiphyton was strongly dependent on underwater light conditions. Differences in epiphyton composition and biomass between the center and the periphery of the bulrush stand were negligible. We conclude that the availability of colonizing surface is not a relevant driver for the colonization and growth of these epiphyton assemblages. The epiphyton in pampean lakes may remain stable and resilient for relatively long periods, even when confronted with envi - ronmental perturbations, and changes in these communities will only occur in relation to radical alterations in light and nutrient availability.

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 15:35-45 (2012) - DOI: https://doi.org/10.3354/ab00404 Changes in propagule formation and plant growth in Potamogeton crispus induced by exogenous application of gibberellic acid (GA3) and 6-benzyladenine (6-BA) Lei Wang1, Tewu Yang1,*, Duanwei Zhu2, Junchi Xu1, Zhongnan Nie3, Guozheng Yang1 1College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China 2Laboratory of Plant Nutrition and Ecological Environment Research, Center for Microelement Research, Huazhong Agricultural University, and Key Laboratory of Subtropical Agriculture and Environment, Ministry of Agriculture, Wuhan 430070, PR China 3Department of Primary Industries, Private Bag 105, Hamilton, Victoria 3300, Australia *Email: yangtewu@mail.hzau.edu.cn ABSTRACT: Submerged aquatic macrophytes such as Potamogeton crispus can absorb large quantities of nutrients from sediment and water, and therefore mitigate pollution and improve water quality of polluted lakes. Turions are the main propagules of P. crispus; their formation is an important process in the life cycle of the plant and relates closely to the population dynamics of the species in lakes. The clarification of the physiological mechanisms specific to plant hormone regulation in propagule formation versus plant growth will help to better understand the population decline in eutrophic waters and to develop management strategies for the species. In the present study, different treatment concentrations and application frequencies of gibberellic acid (GA3) and 6-benzyladenine (6-BA), a cytokinin substances, were used to investigate their effects on propagule formation and plant growth in this plant. The results showed that, when a cultured plant was treated with GA3 or 6-BA before propagule morphogenesis, propagule production was inhibited or delayed. Under repeat applications of GA3 or 6-BA, propagule formation was arrested completely except in the treatment with 2.5 mg l−1 GA3, which led to some phylloclade turions. Plants treated with GA3 had more phylloclade turions and longer turions compared to the control, whereas less difference was observed under 6-BA treatments. This suggests that cytokinin is a more effective substance in regulating propagule differentiation in P. crispus. Morphological and physiological analysis showed that the propagule formation was more sensitive than plant growth to the plant growth regulators. Both plant growth regulators promoted photosynthetic pigments in plants but inhibited starch accumulation in propagules, which may be related closely to the changes in propagule growth and development. KEY WORDS: Turion · Cytokinin · Gibberellin · Carbohydrate accumulation · Physiological characteristics Full text in pdf format PreviousNextCite this article as: Wang L, Yang T, Zhu D, Xu J, Nie Z, Yang G (2012) Changes in propagule formation and plant growth in Potamogeton crispus induced by exogenous application of gibberellic acid (GA3) and 6-benzyladenine (6-BA). Aquat Biol 15:35-45. https://doi.org/10.3354/ab00404 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 15, No. 1. Online publication date: March 21, 2012 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2012 Inter-Research.

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 14:99-103 (2011) - DOI: https://doi.org/10.3354/ab00386 NOTE Diet of spring and summer spawning groups of Illex argentinus inhabiting coastal waters in San Matias Gulf (northern Patagonia, Argentina) Augusto César Crespi-Abril1,*, Maria Magdalena Trivellini2 1Centro Nacional Patagónico (CENPAT-CONICET), Boulevard Brown s/n, Puerto Madryn 9120, Chubut, Argentina 2Universidad Nacional de la Patagonia San Juan Bosco, Boulevard Brown s/n, Puerto Madryn 9120, Chubut, Argentina *Email: crespi@cenpat.edu.ar ABSTRACT: To study the diet of 2 coastal spawning groups of Illex argentinus, we analyzed the stomach contents of 3645 specimens (10 to 36 cm in mantle length). More than half (58%) of observed stomachs were empty. There were no differences in the prey consumed between specimens of different sex and maturity stages. Additionally, no differences were observed in the diet among individuals belonging to either the summer or spring spawning groups. The most frequent prey item was fishes (0.79 frequency of occurrence), followed by cephalopods (0.18) and lastly by crustaceans (0.09). The seasonal variation of empty stomach frequency and the mean stomach fullness revealed that squids fed more actively in spring and summer and mainly preyed upon small pelagic fishes. KEY WORDS: Illex argentinus · Near-shore waters · Diet · Cephalopods Full text in pdf format PreviousCite this article as: Crespi-Abril AC, Trivellini MM (2011) Diet of spring and summer spawning groups of Illex argentinus inhabiting coastal waters in San Matias Gulf (northern Patagonia, Argentina). Aquat Biol 14:99-103. https://doi.org/10.3354/ab00386 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 14, No. 1. Online publication date: December 12, 2011 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2011 Inter-Research.

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 14:87-98 (2011) - DOI: https://doi.org/10.3354/ab00377 Use of oxidative stress biomarkers in Carcinus maenas to assess littoral zone contamination in Tunisia Jihene Ghedira1, Jamel Jebali1, Mohamed Banni1, Lassaad Chouba2, Hamadi Boussetta1, Juan López-Barea3, José Alhama3,* 1Laboratory of Biochemical and Environmental Toxicology, Higher Institute of Agriculture, Chott-Mariem, 4042 Sousse, Tunisia 2Chemical Laboratory, Higher Institute of Marine Sciences and Technology, La Goulette Center, 2060 Tunis, Tunisia 3Department of Biochemistry and Molecular Biology, University of Córdoba, Severo Ochoa Building, Rabanales Campus, Highway A4, Km 396a, 14071 Córdoba, Spain *Email: bb2alcaj@uco.es ABSTRACT: Biological effects of pollutants were studied in Carcinus maenas crabs from 3 polluted sites (Bizerte, Teboulba, Gargour) along the Tunisian littoral zone using biochemical biomarkers. A metal contamination gradient was found, Bizerte standing out as the most metal-polluted area. Gargour animals nonetheless showed higher oxidative stress responses, such as glutathione reductase and 6-phosphogluconate dehydrogenase activities, as well as malondialdehyde (MDA) levels in gills. The gills showed higher lipid peroxidation than did the digestive gland, in keeping with their respiratory role. Animals were also exposed for different periods to 2 model pollutants, cadmium and chlorpyriphos-ethyl. Although cadium induces oxidative stress, mainly in gills, thus increasing lipid peroxidation, principal-component analysis indicated that metal content in sediments and crabs from in-field monitoring does not fully correlate with oxidative stress biomarker responses. Catalase and MDA were the most sensitive biomarkers, and gills the most responsive organ. A lower catalase content in gills was linked to higher MDA levels. KEY WORDS: Biomonitoring · Biochemical effects · Antioxidant enzymes · Lipid peroxidation · Multivariate analysis · Digestive gland · Gills · Metals · Organophosphates · Sediment pollution Full text in pdf format PreviousNextCite this article as: Ghedira J, Jebali J, Banni M, Chouba L, Boussetta H, López-Barea J, Alhama J (2011) Use of oxidative stress biomarkers in Carcinus maenas to assess littoral zone contamination in Tunisia. Aquat Biol 14:87-98. https://doi.org/10.3354/ab00377 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 14, No. 1. Online publication date: December 06, 2011 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2011 Inter-Research.

Knowledge of the adaptive ability of the highly invasive fish Gambusia holbrooki to new habitats is essential for determining its invasion potential. Our main objective was to assess the life-history of G. holbrooki in saline streams by studying its abundance, size and age structure, growth and condition. Two populations inhabiting similar streams of different salinity in the southeastern Iberian Peninsula were monitored over a 2 yr period. In both populations, the life- history of the species was characterized by a short life span, a long recruitment period with a mas- sive emergence of young-of-the-year and fast growth of individuals during the first months of their lives. The species showed a less intense recruitment (6.9% of juveniles vs. 46.4% during the recruitment period) and an earlier end of the recruitment period (at least 2 mo) in the hypersaline system, although abundance, hepatic condition and female somatic condition were higher. In addition, temporary increases in salinity diminished population abundance, recruitment, and somatic and hepatic condition. Both populations showed similar seasonal abundance variation patterns, population structures, growth rates, and somatic and hepatic condition cycles. Other environmental factors independent of salinity could have influenced the differentiation in life- history of the species between populations, thus disguising direct relationships between salinity and life-history. However, the studied parameters show that G. holbrooki presents a great ability to adapt to lotic systems with high and different levels of salinity.

In order to understand the ecological risks caused by organotin compounds (OTs) in diadromous fish migrating between sea and freshwater, tributyltin (TBT) and triphenyltin (TPT) com- pounds, and their breakdown products, were determined in the catadromous eels Anguilla mar- morata and A. bicolor pacifica, collected in Vietnam waters. Ontogenic changes in otolith strontium (Sr) and calcium (Ca) concentrations were examined along life history transects in order to determine habitat use in the eel. There were generally no significant correlations between TBT and TPT accu- mulation and various biological characteristics such as total length (TL) and body weight (BW). In A. bicolor pacifica, TBT and the total butyltin (BT) concentrations of yellow-stage eels (immature eels) were significantly higher than those in silver-stage eels (mature eels). This suggests that yellow-stage eels have a higher risk of contamination by TBT than silver-stage individuals. Positive linear relation- ships were found between Sr:Ca ratios, total BTs and total phenyltins. These results suggest that the ecological risk of OTs in these eels increases with increasing sea residence period. Thus, migratory history and maturation stage are the most important factor for OT accumulation in catadromous eels.

Studies of the regulation and importance of physiological processes such as coral photo- synthesis and respiration on coral reefs require knowledge of spatio-temporal patterns of variability at different scales. Oxygen microelectrodes were used to measure photosynthesis and dark respira- tion of 2 corals, Pocillopora damicornis and Turbinaria reniformis, in the northern (Lizard Island) and central (Davies and Broadhurst Reefs) regions of the Great Barrier Reef (GBR) in winter and summer. Genetic characterisation of Symbiodinium revealed that P. damicornis hosted a single symbiont type (Symbiodinium C1) in both regions, whereas T. reniformis harboured 2 types, dependent on location. Colonies at Lizard Island harboured Symbiodinium D, whereas colonies at Davies Reef harboured Symbiodinium C2. Rates of gross photosynthesis were greater in the central than in the northern GBR in summer. A similar pattern was detected for dark respiration rates in T. reniformis. No seasonal change in either photosynthesis or dark respiration was evident in the northern GBR, possibly due to less annual variability in light conditions, and for T. reniformis, additionally the presence of Symbio- dinium D. These results highlight that environmental conditions coupled with regional-scale distrib- ution of Symbiodinium are likely to exert important influences on respiration and photosynthetic per- formance of reef-building corals.