High-Temperature Effects on Growth and Propagule Formation in Hydrilla Biotypes

In consecutive greenhouse studies, growth and propagule formation were examined first in monoecious hydrilla [Hydrilla verticillata (L.f.) Royle], then in dioecious hydrilla, at three temperature levels (25, 30, and 35 C) and contrasted over three periods of growth (8, 12 and 16 wks). Each biotype was grown under natural photoperiods, decreasing from 14 hrs (in Oct, Nov, and Dec). For both biotypes, total biomass and root-to-shoot ratios were significantly reduced at 35 C; greater biomass was produced both at 25 and 30C. Increases in growth period generally enhanced total biomass and shoot production; however, shoot length was unresponsive to growth periods beyond 8 wks. The 35C treatment strongly impeded tuber formation and eliminat4ed the production of axillary turions; the number and biomass of these propagules peaked at lower temperatures under short photoperiods after 12 to 16 wks. Shoot elongation was stimulated with increases in temperature and was especially pronounced in the dioecious biotype. Notably, in the monoecious biotype, the number of shoots as a potential source of fragments, and tuber production (although reduced) occurred at relatively high levels under unfavorably hihg-temperature (35C) conditions. These results suggest that monoecious hydrilla may be better adapted to high temperatures than previously shown, and that the distribution of both biotypes in the U.S. could overlap further in southern states.

Integration of technologies for understanding the functional relationship between reef habitat and fish growth and production

Functional linkage between reef habitat quality and fish growth and production has remained elusive. Most current research is focused on correlative relationships between a general habitat type and presence/absence of a species, an index of species abundance, or species diversity. Such descriptive information largely ignores how reef attributes regulate reef fish abundance (density-dependent habitat selection), trophic interactions, and physiological performance (growth and condition). To determine the functional relationship between habitat quality, fish abundance, trophic interactions, and physiological performance, we are using an experimental reef system in the northeastern Gulf of Mexico where we apply advanced sensor and biochemical technologies. Our study site controls for reef attributes (size, cavity space, and reef mosaics) and focuses on the processes that regulate gag grouper (Mycteroperca microlepis) abundance, behavior and performance (growth and condition), and the availability of their pelagic prey. We combine mobile and fixed-active (fisheries) acoustics, passive acoustics, video cameras, and advanced biochemical techniques. Fisheries acoustics quantifies the abundance of pelagic prey fishes associated with the reefs and their behavior. Passive acoustics and video allow direct observation of gag and prey fish behavior and the acoustic environment, and provide a direct visual for the interpretation of fixed fisheries acoustics measurements. New application of biochemical techniques, such as Electron Transport System (ETS) assay, allow the in situ measurement of metabolic expenditure of gag and relates this back to reef attributes, gag behavior, and prey fish availability. Here, we provide an overview of our integrated technological approach for understanding and quantifying the functional relationship between reef habitat quality and one element of production – gag grouper growth on shallow coastal reefs.

The Effects of Salinity, Temperature, and Food on the Growth and Reproductive Output of Polydora nuchalis Woodick, 1953

Polydora nuchalis Woodwick, 1953 (Polychaeta: Spionidae) is a protandric hermaphrodite commonly inhabiting intertidal mud flats in southern California. The species exhibits lecithotrophic larval development and adelphophagia. Reproduction of P. nuchalis was monitored for a year at four sites: Catalina Harbor, San Gabriel River, Huntington Harbour, and Malibu Lagoon. Females deposited from 11 to 31 egg capsules in their tubes, with up to 230 eggs per capsule. An average of 3% of the eggs developed into larvae: the remaining were nurse eggs serving as food for the developing larvae. Reproductive output was quantified by determining the number and size of larvae and nurse eggs for individual capsules. Significant differences among the four populations were found for all the quantified variables. In addition, two size classes of nurse eggs were found to exist in capsules from all of the sites. Egg capsules were found throughout the year at San Gabriel River, but none were found during the winter months at the remaining three sites. Size/frequency data for juveniles and adults of the Catalina Harbor population indicate an annual cycle of recruitment. The laboratory experiment consisted of a 3 x 3 x 2 £actor1al design with replication testing the effects of temperature, salinity, and food supply on growth and reproduction of P. nuchalis. Increasing temperature resulted in significantly increased survivorship, growth rates, and percentage reproduction. It also produced a significant decrease in the size of the nurse eggs and the volume of food per larva. The number of egg capsules was maximum at the intermediate temperature. Increasing the salinity resulted in significant increases in survivorship and Class I nurse egg size. Increaaing food availability produced a significant increase in the percentage of worms reproducing. The interactive effect of salinity and £ood level produced significant changes in the number of larvae per capsule and the number of nurse eggs per capsule. However, the number of nurse eggs per larva did not differ significantly among the experimental treatment groups. (PDF contains 129 pages)

Age, growth and life history of Klamath River Basin steelhead trout (Onchorhynchus mykiss irideus) as determined from scale analysis

Adult steelhead (Oncorhynchus mykiss irideus) scales were analyzed from eight fall-run, two spring-run, and one winter-run stocks within the Klamath-Trinity River system, from 1981 through 1983, to provide basic information on age, growth, and life history. The higher degree of half-pounder occurrence of upper Klamath River steelhead stocks (86.7 to 100%) compared to Trinity River steelhead stocks (32.0 to 80.0%) was the major life history difference noted in scale analysis. Early life history was similar for all areas sampled with most juveniles (86.4%) remaining in freshwater during the first two years of life before migrating to sea. Repeat spawning ranged from 17.6 to 47.9% for fall-run, 40.0 to 63.6% for spring-run, and 31.1% for winter-run steelhead. Mean length of adults at first spawning was inversely related to percent half-pounder occurrence in each stock. Ages of returning spawners, back calculated lengths at various life stages, and growth information are presented. (PDF contains 22 pages)

Survival, growth, and yield of brown trout stocked as fingerlings in Hot Creek, California

Four groups of fin clipped brown trout (Salmo trutta) fingerlings were planted in Hot Creek over a six year period. Survival and growth were estimated by fall and/or spring mark-and-recapture surveys. Yield to the angler for two of the tour groups stocked was estimated by stratified random creel surveys. Fingerling survival from the midsummer stocking period to fall averaged 51 %. Overwinter survival from young-of-the-year to yearling fish averaged 49%. Angler harvest of two groups of fingerlings stocked at densities of 16,082 fish/mile averaged 1,704 trout/mile (10.6%) and 194 lbs/acre. Abundant cover and microhabitat suitable tor young trout, ice-free winters, and rapid growth were factors viewed as contributing to high yields. Results do not suggest a change is needed in the general policy of not stocking brown trout fingerlings in California streams. Results do show that fingerlings stocked in Hot Creek, and presumably other productive streams with abundant cover, can effectively fill a void created by limited recruitment. (PDF contains 24 pages.)

Size composition, growth and sexual maturity of bigeye tuna, Thunnus obesus (Lowe), from the Japanese long-line fishery in the Eastern Pacific Ocean

Size composition data of bigeye tuna taken from the eastern tropical Pacific Ocean by Japanese Prefectural experimental training vessels from 1958 to 1964 are examined. A gradient of increasing fish size from east to west is noted. Males increase in ratio over females for the entire range of lengths examined, and beyond 170 cm comprise more than 75 per cent of the total. The first semester of the year is important as a bigeye spawning season. A general relationship between sexual maturity and thermal structure of the water is discussed. At the end of their 12th quarter of life bigeye are about 114 cm long, by the 16th quarter, 137 cm and at the end of 20 quarters, about 153 cm. The long-line fishery in the eastern Pacific has had a marked effect on the size composition of the stocks of bigeye, but whether the fishing has driven the stocks below a point which could afford a maximum sustainable yield could not be determined. (PDF contains 55 pages.)

The effects of supplemental feeds containing different protein: Energy ratios on the growth and survival of Tilapia nilotica (Oreochromis niloticus) in brackishwater ponds

A research was conducted in thirty approximately 100 sq.m earthern ponds of the Brackishwater Aquaculture Centre (BAC), College of Fisheries, University of the Philippines, Leganes Iloilo from November 7, 1982 to March 7, 1983 to evaluate the effects of nine supplemental feeds containing different protein: energy ratios on the growth and survival of Tilapia nilotica in brackishwater ponds. Nine supplemental feeds formulated were with protein levels of 20%, 25%, and 30% each at three energy levels of 3,000 kcals; 3,500 kcals; and 4,000 kcals. There was a control treatment with no feeding so that mean weight gain growth rate, feed conversion rate, and survival were determined. Fish fingerlings were acclimated from 0-29 ppt. salinity before the experiment and 20% of fish in each treatment were sampled after every 30 days. Growth rates were significantly different and increased with increasing energy level at the 30% protein feeds but decreased at high energy levels in the 20% and 25% protein feeds. Feed conversion was significantly different due to interaction between protein and energy levels in the feeds, and was better at the 30:3,500 kcals feeds having a feed conversion of 1.55 g. Survival was not significantly different

Growth and age composition of northern bluefin tuna, Thunnus thynnus, caught in the Eastern Pacific Ocean, as estimated from length-frequency data, with comments on trans-Pacific migrations

ENGLISH: The spawning of Pacific northern bluefin tuna, Thunnus thynnus, takes place only in the western Pacific Ocean (WPO), but substantial numbers of the juveniles migrate to the eastern Pacific Ocean (EPO), where they remain for several months, or longer, and the.n return to the WPO. Lengthfrequency and tagging data show that many bluefin arrive in the EPO as 1-and 2-year olds, and remain there for one or two fishing seasons before returning to the WPO. The proportion of the fish which make the west-to-east migration varies among years. The numbers of 1-, 2-, 3-, 4, and >4 –year olds in the catches of the EPO are estimated for most years of the 1952-1991 period. SPANISH: EI desove del atun aleta azul del norte del Pacifico, Thunnus thynnus, ocurre solamente en el Océano Pacifico occidental (WPO), pero números substanciales de los juveniles migran al Océano Pacifico oriental (OPO), donde permanecen unos meses, 0 mas, antes de regresar al WPO. Datos de marcado y frecuencia de talla indican que muchos aletas azules llegan al OPO a 1 o 2 anos de edad, y permanecen alIi una 0 dos temporadas de pesca antes de regresar al WPO. La proporcion de los peces que migra del oeste al este varia entre anos. Se estima el numero de peces de 1, 2, 3, 4, Y>4 anos de edad en las capturas del OPO para la mayoria de los anos del periodo de 1952-1991. (PDF contains 40 pages.)

Preliminary studies on the effects of light duration on the growth and performance of Clarias gariepinus fingerlings

The effects of light duration on the growth and performance of Clarias gariepinus fingerlings were investigated using artificial methods to simulate continuous day length and absolute darkness. The normal day length (12-H Light and 12-H Darkness) served as the control. Among some of the factors affected by the varying photoperiods there were body coloration, feeding efficiency, survival rate and Specific Growth Rate (SGR). There was notably no significant difference between the SGR of the 0-photoperiod culture and the control (P>0.05) but there was significant difference between the 0-photoperiod and the 24-H photoperiod experiment (P<0.05). The haematological profile analysed showed various degrees of changes in the blood parameters of fish cultured under different photoperiods. These changes however, did not show significant differences when subjected to statistical analysis

The growth and survival rate of Oreochromis niloticus fries fed (private) with varying percentages of Leucaena leucocephala leaf meal based diets

A-ten-week feeding trial was carried out to evaluate the growth and survival rate of Oreochromis niloticus fed with varying percentage levels of Leucaena leucocephala leaf meal based diets. The substitution rates of L.leucocephala leaf meal for groundnut cake in the various diets were 0% - Diet 1, 25% - Diet 2, 50% - Diet 3 and 75% - Diet 4. Ten fries with an average weight of 0.44g were stocked at the rate of 10 fish per bowl and fed at 5% body weight. Diet 1 with 0% inclusion of Leucaena leaf meal gave a significant difference (P>0.05) in growth and survival rate compared with diets 2, 3 and 4. The water quality parameters recorded were appropriate for fish culture

The growth and survival rate of (private) Oreochromis niloticus fingerlings fed with varying percentages of Leucaena leucocephala leaf meal based diets

A-ten-week feeding trial was carried out to evaluate the growth and survival rate of Oreochromis niloticus fed with varying percentage levels of Leucaena leucocephala leaf meal as a substitute for groundnut cake. The levels in the various diets were 0% - Diet 1, 25% - Diet 2, 50% - Diet 3 and 75% - Diet 4. Ten fingerlings with an average weight of 0.44g were stocked at the rate of 10 fish per bowl and fed at 5% body weight. Diet 1 with 0% inclusion of leucaena leaf meal gave a significant difference (P>0.05) in growth and survival rate compared with diets 2, 3 and 4. The water quality parameters recorded were appropriate for fish culture

An investigation of the effect of replacing fish meal with soyabean meal, groundnut cake and blood meal at varied proportion on growth and food utilization of the Clarias anguillaris fingerlings fed in outdoor hapas

Fingerlings of Clarias anguillaris obtained from a homogenous source through induce breeding and each with a mean weight of 2.8g were stocked in ten hapas each measuring 1.0x1.0m in outdoor concrete tank and were fed for eight (8) weeks. Results shows that the best growth rate was recorded among fingerlings fed fish meal as the only protein source (TD5) while DT2 containing soya bean, groundnut cake (40%), blood meal as the protein sources came next. The growth rate of fingerlings fed DT2 (40 % groundnut cake, 10% soyabean meal and 10% blood meal) was higher than those fed DT4 containing 10% fish meal but lower than those fed DT5 which has fish meal as its sole source of protein (53.0%). Analysis of various growth parameters like SGR, FCR and PER. shows that DT5 was the overall best diet but there was no significant statistical difference in weight gained by fish fed the five diets (P <0.05)

Comparative growth and survival of fry of Clarias gariepinus (B), Clarias anguillaris (L), Heterobranchus bidorsalis (G), Heteroclarias, Clariabranchus and Clarias hybrids under outdoor nursery management system

Hybrids of Clariid catfishes; C. gariepinus (Netherlands), C. anguillaris, H. bidorsalis and their parental species were monitored for 8 weeks in 2 x 2 x 1m outdoor concrete tanks. The fry were fed NIFFR diet (40% crude protein) twice daily, 7 days of the week. Growth and survival records were taken weekly. The male HEB X female CLG hybrid showed an overall highest performance in growth rate while the lowest was recorded in male CLA X female CLG hybrid. The male HEB X female CLG hybrid grew at a faster rate than its reciprocal hybrid. In view or their growth rate, it is possible that the growth and survival rates or H. bidorsalis especially at the fry to fingerling stage could be improved through hybridization. The hybrid have potential as commercial food fish

Coastal plant growth and CO2 enrichment: Can the productivity of black needle rush keep pace with sea level rise?

The rate of sea level change has varied considerably over geological time, with rapid increases (0.25 cm yr-1) at the end of the last ice age to more modest increases over the last 4,000 years (0.04 cm yr-1; Hendry 1993). Due to anthropogenic contributions to climate change, however, the rate of sea level rise is expected to increase between 0.10 and 0.25 cm year-1 for many coastal areas (Warrick et al. 1996). Notwithstanding, it has been predicted that over the next 100 years, sea levels along the northeastern coast of North Carolina may increase by an astonishing 0.8 m (0.8 cm yr-1); through a combination of sea-level rise and coastal subsidence (Titus and Richman 2001; Parham et al. 2006). As North Carolina ranks third in the United States with land at or just above sea level, any additional sea rise may promote further deterioration of vital coastal wetland systems. (PDF contains 4 pages)