We collected 1,399 striped bass Morone saxatilis from western Albemarle Sound, North Carolina, during May through October of 2002 and 2003 to characterize diet, prey type selectivity, and prey size ...selectivity. Herrings Alosa spp., Atlantic menhaden Brevoortia tyrannus, bay anchovy Anchoa mitchilli, silversides Menidia spp., and yellow perch Perca flavescens dominated the diets of age‐1 striped bass, while Atlantic menhaden dominated the diets of older striped bass. Selectivity was calculated for three categories of striped bass (ages 1, 2, and 3+ 3–7) based on fish prey collections from a 61‐m beach seine and a 76‐m purse seine. Striped bass of all ages primarily consumed fish prey regardless of the month or year. Each age category of striped bass selected for one or more species of prey from the suborder Clupeoidei. Age‐1 striped bass selectivity of Alosa spp. generally increased with the progression of each sampling season, whereas selectivity for Atlantic menhaden, Menidia spp., and yellow perch decreased over time within each season. Striped bass of all ages displayed strong selection for Atlantic menhaden and strong selection against spiny‐rayed fish prey. Striped bass displayed selection for specific prey, although the mechanisms responsible for selection appear to vary through time and may differ for different prey types. Striped bass either displayed neutral size selectivity or selected for relatively small prey. The mean and maximum sizes of fish prey increased with increases in striped bass size, but the minimum prey size changed little. Our results of seasonal and age‐specific changes in selectivity will be valuable for modeling the impact of striped bass predation on resource prey species.
We examined diet, dietary niche width, diet overlap, and prey size–predator size relationships of blue marlins Makaira nigricans, dolphinfish Coryphaena hippurus, yellowfin tuna Thunnus albacares, ...and wahoos Acanthocybium solandri caught in the western North Atlantic Ocean during the Big Rock Blue Marlin Tournament (BRT) in 1998–2000 and 2003–2009 and dolphinfish captured outside the BRT from 2002 to 2004. Scombrids were important prey of blue marlins, yellowfin tuna, and wahoos; other frequently consumed prey included cephalopods (for yellowfin tuna and wahoos) and exocoetids (for yellowfin tuna). Dolphinfish diets included exocoetids, portunids, and conspecifics as important prey. Blue marlins and wahoos consumed relatively few prey species (i.e., low dietary niche width), while dolphinfish had the highest dietary niche width; yellowfin tuna had intermediate niche width values. Maximum prey size increased with dolphinfish size; however, the consumption of small prey associated with algae Sargassum spp. occurred across the full size range of dolphinfish examined. Most interspecific diet overlap values with dolphinfish were not significant; however, blue marlins, yellowfin tuna, and wahoos had significant diet overlap due to their reliance on scombrid prey. Prey types found in blue marlins, dolphinfish, and wahoos were more consistent among BRT years than prey found in yellowfin tuna. The prey of yellowfin tuna and wahoos collected during BRT years correlated with historic (early 1980s) diet data from North Carolina, the Gulf of Mexico, and the Bahamas. Based on principal components analysis, diets from several oceans clustered together for blue marlins, dolphinfish, yellowfin tuna, and wahoos. Although differences were found, the diets of each predator were largely consistent both temporally (e.g., over the past three decades in the Gulf Stream) and spatially (among oceans), despite potential effects of fishing or environmental changes.
Gafftopsail catfish Bagre marinus were collected at various locations in the eastern half of Tarpon Bay, FL, in the spring of 2000, and mercury levels were measured and compared with results from a ...similar study conducted in 1990. The mean Hg concentration measured in specimens in 2000 was 0.228 ppm, and only one specimen had a Hg concentration that exceeded the consumption advisory of 0.5 ppm. Overall, no significant difference was found between the 2000 and 1990 data, but a considerably lower mean Hg concentration was found in 2000 when comparing groups of fish between years that were similar in mean body weight. All specimens of B. marinus collected in 2000 had Hg concentrations above the level believed to be harmful to fish-eating birds.
Excluder sizes that could simultaneously reduce sizes and numbers of sponge crabs relative to control pots while maintaining sizes and numbers of nonsponged crabs were identified. Male crabs were ...separated by size and female crabs were separated by level of maturity. Brood color and percent fullness were recorded for sponge crabs. Median and mean carapace widths of mature female crabs were similar among treatments. There were no significant pairwise differences in the median carapace width of mature female crabs between treatments. Each excluder treatment caught significantly smaller male crabs than the control, although there was no difference between the two-excluder treatments. The analysis of catch-per-pot data indicated that larger openings permitted the entry of greater number of mature female, legal male, and sponge crabs.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We captured 32 gafftopsail catfish, Bagre marinus, from J.N. 'Ding' Darling National Wildlife Refuge located in Sanibel, Florida in April-May, 2000 to determine the concentration of mercury in muscle ...tissue, and if mercury concentrations had reached the minimum state health advisory level (0.5ppm; wet weight), and to establish a data set for future comparison. We also compared year 2000 mercury levels against those of a 1990 study conducted in the refuge.
Calix4arene tetraethers in the cone conformation bearing four -NH-CO-CH2-P(O)Ph2 (= CMPO) residues on their wide rim and one, two or four omega-amino alkyl residues of various lengths at the narrow ...rim were synthesized. Reaction with dichlorotriazinyl (DCT) functionalized magnetic particles led to complete coverage of the available surface by covalently linked CMPO-calix4arenes in all cases. Magnetically assisted removal of Eu(iii) and Am(iii) from acidic solutions was distinctly more efficient with these particles in comparison to analogous particles bearing the same amount of analogous single-chain CMPO-functions. The best result, an increase of the extraction efficiency by a factor of 140-160, was obtained for attachment via two propyl spacers. The selectivity Am/Eu was in the range of 1.9-2.8. No decrease of the extraction ability was observed, when the particles were repeatedly used, after simple back extraction with water.
Magnetic particles were synthesised for radionuclide removal from nuclear wastes by magnetic separation. Dendrimers with terminal amino groups attached to the particle surface were used to bind ...chelating groups for lanthanides and actinides. This led to a 50–400-fold increase of the distribution coefficients for europium and americium in comparison to the reference particles without the dendrimers. Back-extraction studies have demonstrated the possibility of multiple particle recycling.
We compared abundance, richness, diversity, and community structure of macroepifauna among the seagrasses Halodule wrightii, Thalassia testudinum, and Syringodium filiforme, and unvegetated substrate ...in Tarpon Bay, Caloosahatchee River estuary, Florida. Sampling was conducted using wire-mesh minnow traps deployed over fifty-six 24-h periods from Jan. 1999 to Jan. 2000. A total of 36, 35, 28, and 28 species were identified from Halodule, Thalassia, Syringodium, and unvegetated samples, respectively. The gastropod Nassarius vibex was the most abundant species from Halodule and unvegetated substrate, whereas the pinfish (Lagodon rhomboides) was the most abundant species from Thalassia and Syringodium. Abundance of these codominant species varied seasonally throughout the study. For all taxa combined and for codominants, each seagrass contained greater averages than unvegetated substrate in each season. Seagrasses typically had higher average species richness and diversity than unvegetated substrate in each season. Results indicate that Tarpon Bay typifies subtropical estuaries in that its epifaunal community is dominated by few species, faunal abundances vary seasonally, and more organisms are found in seagrasses than in unvegetated areas. Our results serve as a foundation to compare against future research in an understudied system.
A total of 507 gafftopsail catfish, Bagre marinus, were captured by hook and line in Tarpon Bay and neighboring Pine Island Sound, Florida from June 3, 1999 to May 6, 2000 in order to identify foods ...of this understudied species. A total of 86 (17.0%) specimens contained only unidentifiable food, and 187 (36.9%) specimens were found with empty stomachs. Based on the index of relative importance, the pink shrimp, Farfantepenaeus duorarum, was the most important food for specimens less than or equal to 200 mm fork length (FL), amphipods the most important food for specimens 201-300 mm FL, and unidentifiable fish the most important food for specimens greater than or equal to 301 mm FL. Diet of B. marinus was also compared among four seasons: June through August; September through November, December through February, and March through May. Unidentifiable fish was the most important food for June through August and September through November. Clupeid fishes were the most important food for December through February. The amphipod Ampelisca abdita was the most important food for March through May. The wide variety of foods consumed by B. marinus indicates an opportunistic feeding strategy.
A study was conducted by dipnet to compare community structure and abundance of major taxa of epifauna among Halodule wrightii, Thalassia testudinum, Syringodium filiforme, drift algae, and ...unvegetated bottom in Tarpon Bay, Sanibel, FL. Sampling was conducted roughly once per week from January, 1999, through January, 2000. Samples from unvegetated bottom contained a significantly lower average number of total organisms than any of the four macrophytes. On average, gastropods were the most abundant taxa collected from each species of seagrass, caridean shrimps were the most abundant taxa collected from drift algae, and mysids were the most abundant taxa collected from unvegetated bottom. Among the five habitats, Halodule contained the highest average number of gastropods, mysids and pink shrimp, Farfantopenaeus duorarum. Thalassia contained the highest average number of pagurid crabs and syngnathid fish. Drift algae contained the highest average number of amphipods, caridean shrimps, and the isopod, Harrieta faxoni. For each macrophyte, regression did not reveal consistent relationships between abundances of major taxa, salinity, or percent macrophyte cover. Community composition differed significantly among all five habitats. Numbers of specimens from major taxa were generally found in greater abundance in summer than in winter.
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