Population Biology and Growth of Ozark Cavefish in Logan Cave National Wildlife Refuge, Arkansas

Ozark cavefish, Amblyopsis rosae, is a threatened species endemic to the Springfield Plateau of the Ozark Highlands in Arkansas, Missouri, and Oklahoma. One of the largest known Ozark cavefish populations, located in Logan Cave, Arkansas, was surveyed 25 times over a two-year period between 1993 and 1995. During the study, 147 Ozark cavefish > 30 mm (TL) were marked with visual implant tags and 140 Ozark cavefish were available for recapture; 68 were recaptured 189 times and the rest (72) were never recaptured. Individual Ozark cavefish persisted in Logan Cave for a relatively short time. Only 14% of 80 fish tagged during a previous study in 1992 were recaptured during this study, and half of all recaptured fish disappeared within three months. However, if a fish persisted for at least seven months in the cave, its probability of being recaptured over an additional year was high. Maximum persistence of a tagged fish was 28 months, suggesting these fish have a maximum life-span of 4–5 years. Growth averaged 0.6 mm per month, with maximum recorded growth of 6 mm per month and a maximum size of 65 mm TL. Smaller fish grew faster than larger fish but growth rates were sporadic, with several mid-sized fish (45–49 mm) showing little growth (0–3 mm year^-1) while some fish > 50 mm grew up to 12 mm year^-1. Most fish gained in length during April–October, the same period a maternity colony of gray bats occupied the cave. Gross Ozark cavefish movement over the study period ranged up to 1002 m, with a mean movement of 1.2 m day^-1; movement was positively correlated with Ozark cavefish total length. Death seemed the most likely explanation for loss of tagged Ozark cavefish, including fish that emigrated out of the cave. Little up-stream movement was recorded between reaches and did not account for loss of tagged fish. Reproduction within the cave and immigration from the aquifer accounted for persistence of Ozark cavefish in Logan Cave.     

Movements and growth of tagged young-of-the-year Atlantic croaker (Micropogonias undulatus L.) in restored and reference marsh creeks in Delaware Bay, USA

The residence time, movements, and growth of tagged young-of-the-year Atlantic croaker, Micropogonias undulatus L., were studied from July to October 1998 as measures of the success of a marsh restoration project adjacent to Delaware Bay. A total of 8173 croaker (41-121 mm SL) were tagged from each of two creeks in both marshes during July and August with internal sequential coded wire microtags. A prior tag-retention study in the laboratory found a 95% tag retention rate. Of those tagged, 3.6% were recaptured within and nearby the study creeks using seines, otter trawls, and weirs during a 105-day period. Recapture percentages ranged from 1.5% to 6.1% in individual creeks in the restored marsh. There was some movement of tagged fish between creeks in the restored marsh and out into the main creek, but 95% of the recaptures were made in the subtidal and intertidal portions of the same creek in which they were tagged. Fewer fish were recaptured at the reference marsh (1.6% recapture; n=1489 tagged) up to 50 days after tagging, with no evidence of movement between creeks. The average individual growth rates for recaptured croaker was the same in both restored (0.69 mm/day) and reference (0.63 mm/day) marshes before egress from the creeks in September and October. As a result, both created creeks in a restored marsh and natural creeks in a reference marsh appeared to be utilized as young-of-the-year habitat in a similar way during the summer and until egress out of the marshes during the fall, thus this restoration effort has been successful in creating suitable habitat for Atlantic croaker.     

Age and growth of king and Spanish mackerel larvae and juveniles from the Gulf of Mexico and U.S. South Atlantic Bight

Synopsis Sagittal otoliths from 50 king mackerel 2.9–13.0 mm SL and 72 Spanish mackerel 2.8–22.0 mm SL collected off the southeast U.S. were examined whole at 400 × using a compound microscope-video system. Otoliths of both species had visible, presumably daily, growth increments as well as finer subdaily increments. Otolith growth was directly proportional to growth in standard length for king (r² = 0.91) and Spanish mackerel (r² = 0.86). Spanish mackerel were estimated to be 3–15 d old with a mean absolute growth rate (SL/number of growth increments) and 95% confidence interval of 1.15 ± 0.07 mm · d^–1. The least squares linear equation: SL = –1.30 + 1.31 (age in days), with r² = 0.67 and p < 0.001, described the relationship between length and age. There was a significant positive relationship between absolute growth rate and fish length. King mackerel were estimated to be 3–15 d old with a mean absolute growth rate of 0.89 ± 0.06 mm d^–1. The least squares linear equation: SL = 0.37 + 0.82 (age in days), with r² = 0.77 and p < 0.001, best described the relationship between length and age. The relationship between growth rate and fish length was not significant. The growth rate of king mackerel was slightly higher for fish from the Mississippi River plume than from all other locations combined, while Spanish mackerel growth rates were not significantly different.     

Site fidelity, home range, and tidal migrations of juvenile pinfish, Lagodon rhomboides, in salt marsh creeks

We conducted a series of experiments to determine the movements and fidelity of juvenile pinfish, Lagodon rhomboides, in salt marsh creeks within North Inlet Estuary, SC. In Experiment 1, we investigated the fidelity of pinfish (40–100mm SL) at four subtidal locations (9–617m apart) along the axis of a major creek. We trapped and marked 2,297 individuals and recaptured 15–22% of the fishes released at each site, almost all of which (99.7%) had been marked at the same location of recapture up to 3 months earlier. In Experiment 2, we investigated pinfish movements between subtidal and intertidal areas. In the 8 weeks prior to sampling 2 intertidal creeks, we marked 950 juveniles in the adjacent subtidal areas. Sampling of the 2 flooded intertidal creeks showed that 9–20% of the pinfish collected bore marks, and all had been previously marked at the subtidal site immediately adjacent to the intertidal creek. Gut analysis of 60 individuals revealed that juveniles collected from the intertidal areas at high tide had consumed about ten times more food than those collected at the subtidal sites at low tide. In Experiment 3, we determined the fidelity of recently settled pinfish (<35mm SL) and showed that 15% of the 434 marked pinfish remained in the same area; some were at liberty up to 7 weeks. In Experiment 4, we determined home range by tagging and recapturing juvenile pinfish at sites separated by 20m along a 200m subtidal transect. We estimated that during periods when the intertidal zone was not accessible, the average home range was 9.4m with only 10% of tagged fish moving greater than 20m during the 4 month study. Our results indicate that soon after recruitment to the estuary, pinfish establish strong fidelity for sites within salt marsh creeks and exhibit tidal periodicity in both movements and feeding.     

Food composition of Clarias gariepinus (= C. lazera) (Cypriniformes,Clariidae) in Lake Kinneret (Israel)

The feeding behaviour of the freshwater piscivore, Clarias gariepinus (C. lazera) (C & V 1840) was studied over two periods: 1973–1975 and 1981–1982, in Lake Kinneret (Israel). The total number of fish analysed was 264 and their sizes (SL) and weights varied between 238 and 830 mm (146 to 5728 g). More than fifty species of plants and animals from the plankton, benthos and nekton of Lake Kinneret were identified in the intestines of C. gariepinus. Preyed fish were the most abundant food component (81%) and constituted the highest biomass, with Mirogrex terraesanctae representing the majority (although other species were also found). The potential impact of piscivory in the Kinneret ecosystem is considered.     

The Influence of Environmental Variables on the Distribution and Abundance of Three Elasmobranchs in Tomales Bay, California

We tested the hypothesis that temperature, salinity, and dissolved oxygen affect elasmobranch distribution and abundance in Tomales Bay, California, with monthly longline samples over a 20 month period. We used a Poisson regression under generalized least squares and found that temperature and salinity were the most important factors determining the distribution and abundance of the three most common elasmobranch species, bat ray, Myliobatis californica, leopard shark, Triakis semifasciata, and brown smoothhound shark, Mustelis henlei. Females of all three species were more abundant than males throughout the Bay, and were most abundant in the warmer, more saline inner bay. All three species apparently left Tomales Bay in late fall as water temperatures in the bay decreased to <10–12° C, and returned in early spring after temperatures increased to > 10° C. Three of 257 bat rays tagged in Tomales Bay were recaptured, all within 1km of their tagging location despite having been free for up to 583d.     

A new species of amblycipitid catfish, <Emphasis Type="Italic">Xiurenbagrus gigas</Emphasis> (Teleostei: Siluriformes), from Guangxi,China

A new species of amblycipitid catfish is described based on five specimens (88.0–164.5mm in standard length: SL) collected from the vicinity of Duan, Guangxi Zhuangzu Autonomous Region, southern China. The new species, Xiurenbagrus gigas, is different from all other known amblycipitid catfish, but similar to X. xiurenensis by having two patches of vomerine teeth. The new species can be distinguished from X. xiurenensis by having a larger head (head length: 27.9–34.9% vs. 21.8–26.4% SL; head depth: 14.4–17.9% vs. 12.4–14.1% SL; head width: 22.4–29.4% vs. 18.1–20.3% SL), lower adipose fin (4.6–6.0% vs. 6.5–8.3% SL), shorter distance from dorsal origin to adipose origin (25.7–32.0% vs. 32.9–38.9% SL), longer dorsal fin (21.2–24.9% vs. 16.2–19.1% SL), longer pectoral fin (18.4–20.7% vs. 13.5–16.8% SL), longer pelvic fin (13.1–14.3% vs. 8.8–11.8% SL), and more gill rakers (7–9 vs. 5). Xiurenbagrus gigas, the largest known species in the family Amblycipitidae, is distributed in the Xijiang River, the longest tributary of the Zhujiang (Pearl) River basin.     

Inter-annual Fidelity to Summer Feeding Sites in Arctic Grayling

Inter-annual fidelity to summer feeding sites was assessed in adult Arctic grayling, Thymallus arcticus, in the Kuparuk River, Alaska using long-term (15 years) records of individually tagged fish. The Kuparuk River has been the site of a long-term fertilization experiment which allowed us to evaluate the effects of habitat quality on site fidelity. Fidelity to the entire 5km experimental reach, the reference or fertilized zone of the river and to specific river locations was examined. On average, 32% of the arctic grayling caught in the experimental reach were recaptured within the reach in subsequent years. Grayling that returned to the reach displayed strong fidelity to river zones as well as to specific sites on the river. More than half of the fish were recaptured within 300meters of the site where they were captured in previous years. There was no significant difference in fidelity to either the reference or the more productive fertilized zone. Unexpectedly, fidelity was unrelated to fish size (29–43cm TL) or previous summers growth. Strong site fidelity appears to be an adaptation to a short summer during which sufficient resources must be acquired to sustain the fish through the long (9 month) Arctic winter leaving little time to explore alternative locations.     

The <Emphasis Type="Italic">Leiognathus aureus</Emphasis> complex (Perciformes: Leiognathidae) with the description of a new species

Taxonomic analysis of a group of morphologically similar ponyfishes (Perciformes: Leiognathidae) establishes a complex comprising three valid species: Leiognathus aureus Abe and Haneda, 1972, widely distributed in the western Pacific Ocean (Taiwan, Philippines, Thailand, Singapore, Indonesia, and northern Australia); L. hataii Abe and Haneda, 1972, currently known only from Ambon, Indonesia; and L. panayensis sp. nov. Kimura and Dunlap, currently known only from Panay Island, the Philippines. The L. aureus complex can be defined by the following combination of characters: mouth protruding forward, not downward; small but sharp conical teeth uniserially on jaws; a black line between lower margin of eye and lower jaw articulation; and lateral line incomplete, ending below posterior part of dorsal fin base or on anterior caudal peduncle. Leiognathus hataii differs from both L. aureus and L. panayensis in having a large dark blotch below the spinous dorsal fin base and fewer counts of scales (lateral line scales 50–58 vs. 64–85 in the latter two species; scales above lateral line 7–10 vs. 12–18; scales below lateral line 22–26 vs. 30–41). Leiognathus panayensis is distinguished from L. aureus in having a deeper body (41–51% SL vs. 35–45% SL in the latter), long posterior limb of maxilla (21–25% HL vs. 15–23% HL), wholly scaled belly (vs. naked along preanal median keel), and a dark blotch on nape (vs. absent).     

Evaluation of the sample size used for the rapid bioassessment of rivers using macroinvertebrates

Experiments were designed to investigate selective predation by medium (40–55 mm carapace width: CW) and large (55–70 mm CW) Carcinus maenas when feeding on four bivalves of contrasting shell morphology. Size-selection was examined by presenting individual crabs with a wide size range of Mytilus edulis, Ostrea edulis, Crassostrea gigas and Cerastoderma edule. Medium-sized crabs preferred mussels 5–15 mm shell length (maximum shell dimension: SL) and cockles 5–10 mm SL, whereas large crabs preferred mussels 15–25 mm and cockles 10–20 mm SL. Crabs generally showed no preference for any particular size of either oyster species. Species-selection was examined by presenting individual crabs with paired combinations of the four bivalves in various proportions. When offered mussels and oysters simultaneously, both size categories of crabs consistently selected mussels, and food choice was independent of prey relative abundance. By contrast, C. maenas selected mussels and cockles as expected by the frequency in which each size category of crab encountered the preferred size ranges of prey. Crab preference clearly paralleled the rank order of prey profitability, which in turn was mainly determined by prey biomass, suggesting that active selection takes place at some point of the predation cycle. Experiments with epoxy resin models showed that initial reluctance of crabs to attack oysters was not associated with the ultimate energy reward. Moreover, they suggest that foraging decisions are partly based on evaluations of overall prey shape and volume, and that the minimum dimension of the shell constitutes an important feature which crabs recognise and associate with prey value.     

The effects of predation on the survival and size-distribution of estuarine fishes: an experimental approach

Synopsis The effect of southern flounder,Paralichthys lethostigma, predation on the survival and size-distribution of spot,Leiostomus xanthurus, was investigated using feeding experiments in outdoor tanks and estuarine ponds. In the outdoor tank experiments, southern flounder, 143 mm average standard length (SL), fed for 48 h on spot (25–30 mm SL), over a range of densities (4–20 m^–2). In these trials, flounder showed a Type II functional response to spot density. In the estuarine pond experiment, flounder density (2 or 4 flounders 70 m^–2) contributed significantly to spot mortality relative to predator-free controls. The effect of flounder density on spot mortality was non-linear; in the 4-flounder treatment the daily instantaneous mortality due to flounder (0.0177) was 3.5 times that in the 2-flounder treatment (0.0051). The total spot mortality rate in the 4-flounder treatment (0.028) was similar to that observed from published field observations. Flounder also altered the size distribution of spot relative to predator-free controls. Predation by flounder resulted in fewer intermediate-sized spot at the end of the experiment when compared to predator-free controls. Flounder also significantly reduced survival and mean length of two killifishes,Cyprinodon variegatus andFundulus heteroclitus, that invaded the pond. Flounder predation was a significant size-structuring force on the prey fish assemblage in the pond. Results from both the outdoor tank experiment and the pond experiment indicate that flounder may represent a significant source of mortality for juvenile estuarine fishes.     

Gene-centromere mapping of medaka sex chromosomes using triploid hybrids between Oryzias latipes and O. luzonensis

Four sex-linked genetic markers (SL1, SL2, B2.38 and stsOPQ05-1) on the sex chromosomes of the medaka, O. latipes, were mapped in relation to the centromere by means of triploid hybrids between O. latipes and O. luzonensis. Female F₁ hybrid O. latipes of two inbred strains, Hd-rR and HNI, were crossed with male O. luzonensis. Triploidization was induced by heat-shock treatment. Hatching rate of heat-shock treated eggs was 59%, and that of untreated hybrid eggs was 2%, indicating that most of the hatched fry were triploid. Using these triploid hatched fry, the map distances between the four loci and the centromere were examined. The order was SL2 – centromere – SL1 – B2.38 – stsOPQ05-1 and the map distances were: SL2 – centromere, 1%; centromere – SL1, 18%; SL1 – B2.38, 19%; B2.38 – stsOPQ05-1, 9%. Previous studies using FISH showed that SL2 is located on the short arm of large submetacentric chromosomes, and SL1 was closely linked to SDF (sex-determining factor). The results of gene-centromere mapping of this study show that SL1, B2.38 and stsOPQ05-1 are located on the long arm, and that, SDF is thus also on the long arm of the sex chromosomes.     

Intensive cannibalism and feeding on bregmacerotids in <Emphasis Type="Italic">Champsodon snyderi</Emphasis> (Champsodontidae): evidence for pelagic predation

Analysis of the stomach contents of 1002 specimens of Champsodon snyderi (Champsodontidae) (17.3–91.2mm SL) from Tosa Bay, southern Japan, showed that species to primarily feed on crustaceans and fishes (87.9% by frequency, 37.6% by weight for the former; 17.3% and 60.7% for the latter, respectively), although fishes occurred more often in stomachs of individuals larger than 50mm SL. Champsodon snyderi ingested large prey fishes (60.5–101.0% of predator SL), the maximum weight recorded for a single ingested specimen being 50.9% of the predator weight. Mesopelagic Bregmaceros nectabanus were by far the dominant prey fish, followed by C. snyderi (cannibalism), indicating that C. snyderi leaves the bottom to feed in the pelagic environment during the night.     

Comparison of deep-water coral reefs and lithoherms off southeastern USA

Two types of deep-water coral bioherms occur off the coast of southeastern United States: Oculina and Lophelia/Enallopsammia. The deep-water Oculina bioherms form an extensive reef system at depths of 70–100 m along the shelf edge off central eastern Florida. These reefs are comprised of numerous pinnacles and ridges, 3–35 m in height. Each pinnacle is a bank of unconsolidated sediment and coral debris that is capped on the slopes and crest with living and dead colonies of Oculina varicosa, the ivory tree coral. In comparison, deep-water reefs of Lophelia pertusa and Enallopsammia profunda corals occur at depths of 500–850 m (maximum 150-m relief) along the base of the Florida-Hatteras slope in the Straits of Florida. On the western edge of the Blake Plateau off South Carolina and Georgia, 54-m high banks of Enallopsammia and Lophelia occur at depths of 490–550 m, whereas on the eastern edge of the plateau the reefs form structures 146 m in height and at depths of 640–869 m. The geomorphology and functional structure of both the Oculina and Lophelia reefs are similar. North of Little Bahama Bank, at depths of 1000–1300 m, a region of bioherms is dominated by the coral Solenosmilia sp.; Lophelia is reportedly absent. This paper summarizes 25 years of submersible studies on the deep-water Oculina reefs, describes submersible reconnaissance of deep-water Lophelia reefs off the southeastern United States, and contrasts these types of bioherms with the deep-water lithoherms in the Straits of Florida west of the Bahamas.     

Patterns of nocturnal movement of the long-spined sea urchin<Emphasis Type="Italic"> Diadema antillarum</Emphasis> (Philippi) in Gran Canaria (the Canary Islands,central East Atlantic Ocean)

We tagged individuals of the sea urchin Diadema antillarum (Philippi) around the island of Gran Canaria (The Canary Islands) during winter 2001–2002 using a new technique, consisting of the insertion of a hook fastened to a fishing line into the aboral pole (periproctal membrane). This allowed individual identification of tagged sea urchins. The goals were: (1) to quantify nocturnal movements and the homing behaviour of this echinoid on shallow rocky bottoms, and (2) to assess short term spatial and temporal variability of these movements. Tagged sea urchins displayed clear homing behaviour. The mean distance travelled at night was 3.7±1.2 m (range 1.0–5.1 m). Mean speed of nocturnal movement was 33±26 cm h^–1 (range 5–110 cm h^–1). We observed greater movement at midnight than at the beginning and the end of the night.Communicated by H.-D. Franke     

Improvement in the biocontrol of postharvest diseases of apples with the use of yeast mixtures

Mixtures of yeasts were tested for theirability to control Penicillium expansum andBotrytis cinerea on Red Delicious apple fruits. The occurrence of synergistic or antagonisticinteractions between yeast strains in differentmixtures was also evaluated. Two strains ofRhodotorula (R. glutinis SL 1 and R. glutinisSL 30) and two strains of Cryptococcus (C. albidus SL 43 and C. laurentii SL 62) were selected fordeveloping yeasts mixtures.The R. glutinis SL 1–R. glutinis SL 30 mixtureexhibited a lower effectiveness than eachstrain alone, against both moulds. Othermixtures (R. glutinis SL 1–C. albidus SL 43 and R. glutinis SL 30–C. albidus SL 43) showedsynergism against P. expansum but not against B. cinerea. The R. glutinis SL 1–C. laurentii SL62 mixture was the only mixture which showedsynergism against gray mould. There was not anymixture, which showed high effectivenessagainst both moulds at the same time. Differentresults could be explained by the dynamics ofthe population of the yeasts.By using yeast mixtures, it was possible toimprove biocontrol without increasing theamount of antagonists applied. The synergismobserved could be useful in enhancingbiological control.     

The land/inland-water ecotones and fish population of Lake Valley (West Mongolia)

New data on fish populations of a closed desert watershed of Mongolia were obtained in 1990 and 1991. For this region periodic droughts, with the accompanying disappearance of lakes and some parts of rivers, are typical. Two forms of a Cyprinid species Oreoleuciscus humilis (dwarf Altai osman) occur in this region during wet periods which usually last for 10-30 years. The dwarf form, is characterized by a maximum SL of 200 mm and early maturation (SL = 70 mm, four years of age). It inhabits small desert rivers in dry periods which last for 3–5 years and both rivers and the riparian zone of lakes during wet periods. The larger lake form occurs only in lakes during the wet periods. It can attain a maximum size of 450 mm and matures in six years, SL = 200 mm. These two forms of O. humilis differ in feeding habits, rates of growth, and morphology. The dwarf form feeds mainly on insect larvae and on plants. The lake form consumes the same food items until it reaches 180 mm SL and then becomes piscivorous. Populations of O. humilis in lakes are restored after a dry period, originating anew from river populations of the dwarf form.Currently there is a transition from a dry period to a wet one. Orog-Nur (one of the lakes of Lake Valley) has been filling with water since 1990. In July 1991 the depth of this lake reached 0.5–1.0 m and fish were found in the lake. The large individuals of dwarf form which came to the lake from the Tuyn-Gol River became cannibals, and their growth rate increased rapidly. The homogeneous environment and low food supply in the restored lakes are suggested to be the main causes of these phenomena.     

Long-term increase in Karenia brevis abundance along the Southwest Florida Coast

Data collected along the southwest coast of Florida between Tampa Bay and Sanibel Island on the abundance of the toxic dinoflagellate Karenia brevis from 1954 to 2002 were examined for spatial and temporal patterns. K. brevis was found to be approximately 20-fold more abundant within 5 km of the shoreline than 20–30 km offshore. Overall, K. brevis was approximately 13–18-fold more abundant in 1994–2002 than in 1954–1963. In 1954–1963, K. brevis occurred primarily in the fall months. In 1994–2002, it was more abundant not only in the fall, but also in the winter and spring months. It is hypothesized that greater nutrient availability in the ecosystem is the most likely cause of this increase in K. brevis biomass, and the large increase in the human population and its activities in South Florida over the past half century is a major factor.     

Efficacy of tagging European catfish Silurus glanis (L., 1758) released into ponds

The efficacy and sub‐lethal consequences of single and double tagging European catfish Silurus glanis with Petersen disc and passive integrated transponder (PIT) tags were examined in short (laboratory) and longer‐term (field) experiments. Tag retention in the laboratory was 100%, with normal behaviour (i.e. feeding) in all fish returning within 36 h. In the field, 65 of 120 tagged S. glanis were recaptured from five small study ponds, with 85% retaining their PIT tags, though recapture rates and tagging efficacy were highly variable amongst locations. This is consistent with literature for other fishes, suggesting that tagging efficiency is variable across species and largely context dependent (fish length, tagging location, habitat).     

A Comparison of Floy and Soft VIalpha tags on Hatchery Arctic Charr, with Emphasis on Tag Retention, Growth and Survival

The Floy FTF-69 'fingerling' tag and the soft VIalpha tag are designed to be used on small salmonid fishes (> 100 and > 150mm, respectively). The two tags were compared for 160 days on hatchery-reared Arctic charr, Salvelinus alpinus, (170–209mm). Tag retention and effects on growth rate and survival were analysed. VIalpha-tagged and untagged control fish had similar growth rates and grew significantly faster than Floy-tagged fish during the experiment. Tag retention was significantly higher for Floy tags (94%) than for VIalpha tags (78%). Most VIalpha tag loss (11%) took place within the first 10 days of tagging while there were no Floy tags lost during this period. Survival rates were about equal for all three groups (96–98%), and thus the tags did not seem to affect the survival of charr under hatchery conditions.