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Owers K.A.,Montpellier University | Albanese B.,Nongame Conservation | Litts T.,Fisheries Management
Environmental Management

Riparian zones are critical for protecting water quality and wildlife, but are often impacted by human activities. Ongoing threats and uncertainty about the effectiveness of buffer regulations emphasize the importance of monitoring riparian buffers through time. We developed a method to rapidly categorize buffer width and landuse attributes using 2007 leaf-on aerial photography and applied it to a 65 km section of the Toccoa River in north Georgia. We repeated our protocol using 1999 leafoff aerial photographs to assess the utility of our approach for monitoring. Almost half (45%) of the length of the Toccoa River was bordered by buffers less than 50 ft wide in 2007, with agricultural and built-up lands having the smallest buffers. The percentage of river length in each buffer width category changed little between 1999 and 2007, but we did detect a 5% decrease in agricultural land use, a corresponding increase in built-up land use, and an additional 149 buildings within 100 ft of the river. Field verification indicated that our method overestimated buffer widths and forested land use and underestimated built-up land use and the number of buildings within 100 ft of the river. Our methodology can be used to rapidly assess the status of riparian buffers. Including supplemental data (e.g., leaf-off imagery, road layers) will allow detection of the fine-scale impacts underestimated in our study. Our results on the Toccoa River reflect historic impacts, exemptions and variances to regulations, and the ongoing threat of vacation home development. We recommend additional monitoring, improvements in policy, and efforts to increase voluntary protection and restoration of stream buffers. © Springer Science+Business Media, LLC. Source

Morris T.,University of Cape Town | Avenant-Oldewage A.,University of Johannesburg | Lamberth S.,Fisheries Management | Reed C.,University of Cape Town
Marine Pollution Bulletin

Concentrations of metals in the tissues of the sharks Callorhinchus capensis, Rhinobatos annulatus and Rhinobatos blochii collected in False Bay and Saldanha Bay, South Africa, in 2013 were investigated. Metal concentrations in the tissue of the parasites Gyrocotyle plana infecting the spiral intestine of C. capensis and Proleptus obtusus infecting the stomach of R. annulatus and R. blochii were also analysed. G. plana showed accumulation of arsenic (4073.52. ±. 5561.54. μg/g), manganese (522.16. ±. 578.21. μg/g), lead (64.87. ±. 101.7. μg/g), titanium (1821.42. ±. 1348.16. μg/g) and zinc (12439.57. ±. 9743.60. μg/g). These results when compared to baseline values, showed that accumulation of the metals in G. plana are orders of magnitude higher than those in the surrounding environment and 2 to 6 times the concentration of the surrounding host's tissues. These results show the usefulness of marine endoparasites as early warning indicators of heavy metal pollution. © 2016. Source

Van Der Lingen C.D.,Fisheries Management | Van Der Lingen C.D.,University of Cape Town | Weston L.F.,University of Cape Town | Ssempa N.N.,University of Cape Town | Reed C.C.,University of Cape Town

A multidisciplinary approach has been applied to examine the population structure of sardine Sardinops sagax off South Africa, where this species supports significant fisheries and is also of ecological and eco-tourism importance. Observations of discontinuous sardine distribution patterns, discrete spawning grounds and significant spatial differences in a variety of phenotypic characteristics have suggested the existence of discrete western, southern and eastern sardine sub-populations or stocks. The use of parasites as biological tags to elucidate sardine population structure has recently been investigated, and strong spatial gradients around South Africa in the prevalence, mean infection intensity and mean abundance of a digenean 'tetracotyle' type metacercarial endoparasite considered to be of the genus Cardiocephaloides and found in the humours of fish eyes support and have proved particularly convincing evidence for the sardine multiple stock hypothesis. A discontinuous distribution in the occurrence of another parasite, the coccidean Eimeria sardinae found in fish testes, has provided additional but weaker evidence of discrete stocks. These results have contributed to a changed understanding of the population structure of South African sardine and have significant implications for management of the fisheries for this species. © 2014 Cambridge University Press. Source

Reed C.,University of Cape Town | MacKenzie K.,University of Aberdeen | Van Der Lingen C.D.,Fisheries Management | Van Der Lingen C.D.,University of Cape Town
Bulletin of the European Association of Fish Pathologists

The use of parasites as biological tags for stock identification of marine fish has been successfully implemented in many parts of the world but has not previously been attempted in South Africa. The present study was designed to assess the potential of the method in addressing questions concerning stock structure of the local population of sardines Sardinops sagax (Jenyns, 1842). Seven samples, totaling 102 sardines, were examined from localities ranging from south of Cape Columbine on the west coast to east of Algoa Bay on the east coast. Seven parasite taxa were recorded, including six identified to species level and three new host records. Digenean "tetracotyle" metacercariae infected the eyes at an overall prevalence of 46%, the myxozoan Kudoa thyrsites (Gilchrist, 1924) infected the musculature of 17%, while the parasitic copepods Clavellisa ilishae (Pillai, 1962) and Nothobomolochus fradei (Marques, 1965) each infected the gills of 10%. The coccidian Eimeria sardinae (Thélohan, 1890) Reichenow, 1921 infected the testes of 40% of male sardines. One sardine caught off Port Elizabeth harboured a single specimen of the monogenean gill parasite Mazocraes sardinopsi (Lebedev and Parukhin, 1969), and the muscle of another from Cape Point harboured a single plerocercoid of the trypanorhynch cestode Tentacularia coryphaenae Bosc, 1802. Initial indications are that the "tetracotyle" metacercariae have the greatest potential as biological tags. Source

Rasmussen P.W.,United Road Services | Schrank C.,Fisheries Management | Williams M.C.W.,Fisheries Management
Journal of Great Lakes Research

The manufacture and use of polychlorinated biphenyls (PCBs) was banned in the United States in 1977 after it was determined that these compounds adversely affect animals and humans. The Wisconsin Department of Natural Resources has quantified total PCB concentrations in Lake Michigan chinook (n. =. 765) and coho (n. =. 393) salmon (. Oncorhynchus tshawytscha and Oncorhynchus kisutch, respectively) filets since 1975. We analyzed these data to estimate trends in PCB concentrations in these fish (1975-2010). We used generalized linear models with a gamma error distribution and log link fit to the untransformed concentrations. Trend patterns were examined using graphical smoothing and generalized additive models. We identified a candidate set of models that included time trend and other predictor variables. Using the Akaike Information Criterion to select among models we found the best models for both species included piecewise linear time trends, total body length, % lipid, and collection season as predictor variables. The intersection of the two trends was 1985 for chinook salmon and 1984 for coho salmon. PCB concentrations in both species increased with body length and % lipid, and were higher for individuals caught in the fall. Our data reveals a dramatic decline in PCB concentrations of -. 16.7% and -. 23.9% per year for chinook and coho, respectively, up until the intersection year likely reflecting implementation of restrictions on Aroclor-based PCBs. After the intersection year to 2010, PCB concentrations declined at an annual rate of -. 4.0% (95% CI: -. 4.4% to -. 3.6%) and -. 2.6% (95% CI: -. 3.3% to -. 1.9%) for chinook and coho, respectively. © 2014 International Association for Great Lakes Research. Source

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