Can the effects of anthropogenic pressures and environmental variability on nekton fauna be detected in fishery data? Insights from the monitoring of the artisanal fishery within the Venice lagoon

Nekton communities in transitional ecosystems are naturally adapted to stressful conditions associated with high environmental variability. Human activities in these systems are likely to determine additional stress with a possible effect on fish fauna, hence on fisheries. In order to test the relative importance of natural and anthropogenic factors in determining changes in nekton community, catches (incl. bycatch) from artisanal fisheries (fyke nets) were monitored seasonally in different areas of the Venice lagoon (Italy) between 2001 and 2013. Changes in nekton community composition and in the biomass of target and non-target species/groups were analysed, and the results were related to temporal factors, environmental characteristics and to the variability in anthropogenic pressures. Statistical tests were carried out using a model-based analysis of both univariate and multivariate data. Results highlighted that temporal factors and environmental conditions (i.e. the main chemico-physical descriptors) are more relevant than anthropogenic pressures in explaining spatial and temporal changes in the lagoon nekton assemblage, but that several characteristics of the assemblage, in particular the biomass of some particular categories and of the whole assemblage, are sensitive to human impacts. A particularly negligible effect seemed to be associated with fishing effort, thus suggesting that the monitoring of the local artisanal fishery is suitable also to provide useful information on the evaluation of the status of nekton assemblage

Spatial Diversity in Composition and Structure of Nekton in Ngenep Spring and Its Channels, Karangploso - Malang

Water springs and its channel degradation due to anthropogenic pollution may alter the community structure of aquatic organisms. Water spring degradation tehrefore affect the quality of water as tourism resources. This study aims to investigate the changes in community structure of nekton and determine the relationships between water quality characteristics to the diversity of nekton. The field survey was set up in Ngenep spring and its channels. Results showed that nekton species found in Ngenep spring and its channels consists of 4 classes, 4 orders, 6 families, and 7 species with total 627 nekton samples. It is comprises of fishes, shrimp, frogs and waterstriders. Nekton diversity index (H) in the spring and irrigation channel were in moderate level (1<H<3) while in settlement channel was low (0,67). Evenness values of nekton ranged 0,24 0,53, whereas dominancy index of nekton ranged 0,41 0,74. Evenness value in settlement channel was very low (0, 24) with high dominancy index (0, 74); it indicates that nekton species were spread not evenly in the channel, it dominated by fish Rasbora sp. (highest IVI, 184,95). There were spatial variations of physico-chemical water qualitiy parameters in Ngenep springs and its channels (temperature, stream velocity, turbidity, conductivity, pH, DO, BOD and TOM) which affected to nekton diversity and community structure. Clustering analyses and PCA result shows correlation pattern between nekton distribution with physico-chemical water quality parameters. However, physico-chemical water quality parameters in Ngenep springs and its channel were still optimum as nekton habitat (PP No. 82/ 2001). Keywords: Community structure, Nekton, Spatial diversity, Spring, Water channe

STUDI KEANEKARAGAMAN NEKTON BERDASARKAN KONDISI FISIK KAWASAN KONSERVASI KURA-KURA di UNIVERSITAS BENGKULU

Tujuan dari penelitian ini adalah untuk mengetahui struktur, komposisi, keragaman, kelimpahan dan kekayaan nekton serta hubungan antara faktor lingkungan fisik dengan keragaman nekton di area konservasi kura-kura Universitas Bengkulu. Penelitian dilakukan pada bulan Januari sampai April 2017 menggunakan tehnik purposive sampling dengan pengambilan sampel menggunakan metode line transek. Data yang dikumpulkan dari area konservasi kura-kura masingmasing dengan menggunakan alat tangkap jala insang dan tangkap bubu dengan 2 kali pengulangan. Hasilnya menunjukkan bahwa oganisme aquatik golongan nekton yang ditemukan pada 2 lokasi yang berbeda terdapat 7 spesies dan 4 Spesies. Dari analisis hasil indeks shanon menunjukkan tingkat keanekaragaman spesies nekton pada kedua area konservasi termasuk kategori rendah dengan nilai H’ Kolam Taman Pintar=0,28 dan H’ Kolam Pipi Putih=0,17. Hasil analisis regresi menunjukkan bahwa terdapat hubungan antara faktor lingkungan fisik dengan kekayaan nekton di area konservasi. Kata kunci: keragaman, nekton, area konservasi, lingkungan fisi

Diet composition of fish species from the southern continental shelf of Colombia

The diet composition of 30 fish species belonging to 16 families from the Pacific Coast of Colombia is described. Benthic crustaceans (37.5%) and bony fishes (23.7%, chiefly demersal) were the most important food items for the fish species analyzed. Data on diet composition of the fish species are presented for the first time which can be a source of information for trophic modeling

Nekton utilization of restored habitat in a Louisiana marsh

Marsh terracing and coconut fiber mats are two restoration techniques currently being implemented at Sabine National Wildlife Refuge. We tested two hypotheses related to these restoration techniques: (1) marsh terracing enhances nekton assemblages, so that nekton use is similar to those at natural marsh edges, and (2) coconut matted marsh edges enhance SAV recruitment, so that nekton use is similar to those found at natural marsh edges. Samples from terraces and coconut matted marsh were compared to samples from the natural marsh and open water habitats. We measured the following variables at each habitat: (1) nekton density and abundance, (2) nekton biomass, (3) nekton size, (4) nekton diversity, and (5) nekton species composition. Using a collapsible throw trap with 3 mm mesh and a 3 x 2 m straight seine, 180 nekton samples were collected at four sampling dates from winter 2001 to fall 2002. Six habitat types were sampled: (1) natural marsh edge (\u3c 1 m from marsh - water interface), (2) coconut matted marsh edge, (3) terrace edge, and (4), (5), (6) open water (50 m from marsh - water interface for all 3 edge types). Environmental variables that may be influenced by restoration status were also monitored at each habitat. Samples from terraces and coconut matted marsh were compared to samples from the natural marsh edge and open water habitat. Results indicated that nekton variables at coconut matted edge and open water, natural edge, and terrace edge were not significantly different (p \u3e 0.332). Nekton density, biomass, and diversity were lower in open water habitats associated with natural marsh and terraces than in the other four habitats (p \u3c 0.0001). Coconut matted and natural marsh edges had significantly higher numbers of some benthic dwelling species (e.g. blue crab Callinectes sapidus, white shrimp Litopaenaus setiferous, naked goby Gobiosoma bosc, clown goby Microgobius gulosus, Gulf pipefish Syngnathus scovelli) than terrace marsh edges (p \u3c 0.0004), potentially due to differences in substrate caused by construction of the terraces. Researchers have suggested that decreased benthic habitat quality at dredged material marshes is related to an impaired infaunal community and differences in sediment texture. At Sabine NWR, terracing and coconut matting increased nekton utilization 4.5 times above that in open water habitat by enhancing and increasing marsh edge relative to open water. The value of terrace and coconut matted marsh habitat for individual species may vary depending on their niche requirements. Future research on terrace success at providing nekton habitat should address nekton growth rates and correlate nekton composition to the infaunal community

Ecological equivalency of living shorelines and natural marshes for fish and crustacean communities

Salt marshes provide valued services to coastal communities including nutrient cycling, erosion control, habitat provision for crustaceans and fish (including juvenile and forage fish), and energy transfer from the detrital based food web to the greater estuarine system. Living shorelines are erosion control structures that recreate natural shorelines, such as fringing marshes, while providing other beneficial ecosystem services. Living shorelines are expected to provide fish and crustacean (nekton) habitat, but few comprehensive studies have evaluated nekton habitat use across a range of living shoreline settings and ages. We sampled the intertidal marsh and subtidal shallow water nekton community at 13 paired living shoreline and reference marsh sites, with living shorelines ranging in age from 2 to 16 years from construction. We compared nekton diversity, nekton community abundance, nekton community biomass, forage abundance, and juvenile abundance at reference marshes and living shorelines. Our results indicate that living shorelines are providing suitable marsh habitat for nekton communities, including juveniles and forage base species. The difference in living shoreline construction (rock sill, soil composition) did not appear to diminish habitat quality in the marsh or in nearshore waters, and rock sills may provide enhanced structural shoreline habitat. Living shorelines have the potential to combat marsh habitat loss and provide resilient nekton nursery habitat

Valuing New Hampshire Salt Marshes: An Approach to Measuring Ecosystem Services

David Burdick presented work a method for estimating the ecosystem services benefits of salt marsh restoration. The approach combines ecological valuation, which uses structural and functional indicators to measure the marshes response to restoration, and economic valuation, which uses ecosystem services valuations, to determine the net gain in ecosystem services of marsh restoration

Diet composition of fish species from the southern continental shelf of Colombia

The diet composition of 30 fish species belonging to 16 families from the Pacific Coast of Colombia is described. Benthic crustaceans (37.5%) and bony fishes (23.7%, chiefly demersal) were the most important food items for the fish species analyzed. Data on diet composition of the fish species are presented for the first time which can be a source of information for trophic modeling.Diets, Food organisms, Food preferences, Marine fish, Feeding behaviour, Colombia, Pacific coast,

Effects of Slotted Water Control Structures on Nekton Movement within Salt Marshes

Water control structures (WCSs) restrict hydrological connectivity in salt marshes and thereby impede nekton movement within the greater habitat mosaic. Transient fishery species, which spawn outside salt marshes and must get past these barriers to reach spawning areas or salt-marsh nurseries, are especially vulnerable to these structures. Water control structures incorporating slots (narrow vertical openings spanning most of the water column) are thought to improve nekton passage; however, few studies have directly examined nekton passage through WCS slots. Dual-frequency identification sonar (DIDSON) acoustic imaging was used monthly (April-September 2010) on diurnal flood tides to examine nekton movement through 15-cm-wide slots at two identical WCSs located in Louisiana tidal marsh channels. Nekton behavior was compared between these WCSs and a nearby natural salt-marsh creek. Examination of 12 h of subsampled acoustic data revealed large concentrations of salt-marsh nekton at the WCSs (n = 2,970 individuals total), but passage rates through the slots were low (\u3c= 10% of total observed individuals migrated via the slots). Most migrating fish were observed leaving the managed area and swimming against a flood tide. The mean size of migrating individuals (similar to 25 cm TL) did not differ in relation to swimming direction (going into versus exiting the managed marsh) and was similar to that reported from other studies examining similar slot widths. Nekton formed congregations in the WCS channel, but no congregations were observed in the natural salt-marsh creek, even though nekton species composition and sizes were similar among sites. The WCSs in our study appear to function as ecological hot spots, where large individuals may encounter enhanced foraging opportunities but also fishing mortality and where smaller individuals may experience greater predation rates

Gulf Estuarine Research Society 2014 Meeting

Table of Contents: Thank You to Our Sponsors! (p. 3) -- About the Gulf Estuarine Research Society (p. 4) -- Student Travel Award winners (p. 5) -- Abbreviated Schedule (p. 7) -- 2014 Plenary Speaker – Dr. Michael Osland (p. 8) -- 2014 Plenary Speaker – Dr. Maggie Walser (p. 9) -- Full Schedule (p. 10) -- Poster Session Directory (p. 17) -- Oral Presentation Abstracts (p. 21) -- Poster Presentation Abstracts (p. 38) -- Things to Do in Port Aransas (p. 52) -- Greening the Meeting (p. 53) -- Map of University of Texas Marine Science Institute (p. 54)Coastal and Estuarine Research Foundation, Port Aransas, Gulf of Mexico Foundation, Coastal Bend Bays & Estuaries Program, Lotek Wireless Fish & Wildlife Monitoring, Sea Grant Mississippi-Alabama, Sea Grant Louisiana, Sea Grant Texas, The University of Austin Marine Science Institute, Mission-Aransas National Estuarine Research ReserveMarine Scienc