Subtropical Fish Research Articles

Growth patterns, diet composition and reproduction in the ten pounder, Elops lacerta from Ologe lagoon, Lagos, Nigeria

Ten pounder, Elops lacerta, a member of the family Elopidae is a tropical and subtropical fish species. Growth patterns, food and feeding habits and reproduction of 317 specimens of E. lacerta were investigated in Ologe lagoon, Lagos, Nigeria. Diurnal and nocturnal fishing activities were carried out in the lagoon using cast and gill nets. The specimens examined ranged from 90375mm total length (TL) and weighed 4.7214g body weight (BW) respectively. Of the specimens 49.5% were juveniles, 36.3% fingerlings and 14.2% adults. Specimens were classified as unsex, males and females their growth exponential “b” values were allometric and 2.40, 2.27 and 2.27 respectively meaning the fish become lighter for its length as it grows. These values accounted for the robustness of the fish in Ologe. High correlation coefficient was observed in E. lacerta with r=0.76, 0.97, and 0.88 for unsex, male and female specimens respectively. 158 males and 64 females were caught giving 1male:0.41female sex ratio. This was significantly different (P>0.05) from the expected 1male:1female. Diet of the fish consisted of shrimps, plant materials and unidentified food mass. Presence of fish and shrimps in stomachs of the fish indicated its piscivorous and predatory tendency while plant materials connoted its herbivorous habit.

Global distribution of ciguatera causing dinoflagellates in the genus Gambierdiscus

Dinoflagellates in the genus Gambierdiscus produce toxins that bioaccumulate in tropical and sub-tropical fishes causing ciguatera fish poisoning (CFP). Little is known about the diversity and distribution of Gambierdiscus species, the degree to which individual species vary in toxicity, and the role each plays in causing CFP. This paper presents the first global distribution of Gambierdiscus species. Phylogenetic analyses of the existing isolates indicate that five species are endemic to the Atlantic (including the Caribbean/West Indies and Gulf of Mexico), five are endemic to the tropical Pacific, and that two species, Gambierdiscus carpenteri and Gambierdiscus caribaeus are globally distributed. The differences in Gambierdiscus species composition in the Atlantic and Pacific correlated with structural differences in the ciguatoxins reported from Atlantic and Pacific fish. This correlation supports the hypothesis that Gambierdiscus species in each region produce different toxin suites. A literature survey indicated a >100-fold variation in toxicity among species compared with a 2 to 9-fold within species variation due to changing growth conditions. These observations suggest that CFP events are driven more by inherent differences in species toxicity than by environmental modulation. How variations in species toxicity may affect the development of an early warning system for CFP is discussed.

Thermal tolerance varies in tropical and sub-tropical populations of barramundi ( Lates calcarifer) consistent with local adaptation

Barramundi ( Lates calcarifer) are cultured throughout Australasia and increasingly throughout the northern hemisphere. In Australia, barramundi are found in rivers and estuaries across 16 degrees of latitude (10°S–26°S) exposing fish from northern and southern parts of their distribution to different thermal environments. Australian barramundi show strong genetic structuring and this coupled with exposure to varying thermal environments may have led to thermal tolerance differences among populations of interest to aquaculture. To determine if barramundi are thermally adapted to their local environment we used loss of swimming equilibrium (LOSE) as a predictor of upper thermal tolerance in fish from a tropical (Darwin, Northern Territory) and subtropical (Gladstone, Queensland) population and showed that significant differences exist between these two genetically divergent stocks. The tropical population had significantly higher tolerance to warm water temperatures than sub-tropical fish exhibiting a significantly longer time until loss of swimming equilibrium (LOSE) at 40 °C (ANOVA; F 1, 22 = 7.86, P ≤ 0.01). As LOSE challenge tests are not practical to the identification of commercial broodstock animals we also evaluated dissociated caudal fin cells as a sensitive and non-invasive method to determine upper thermal tolerance in this species. Results from dissociated fin cells strongly correlated with those based on LOSE confirming that this method can be used to discriminate populations with different thermal tolerances without having to directly thermally challenge broodstock animals.

Potential climate-change impacts on the Chesapeake Bay

We review current understanding of the potential impact of climate change on the Chesapeake Bay. Scenarios for CO 2 emissions indicate that by the end of the 21 st century the Bay region will experience significant changes in climate forcings with respect to historical conditions, including increases in CO 2 concentrations, sea level, and water temperature of 50–160%, 0.7–1.6 m, and 2–6 °C, respectively. Also likely are increases in precipitation amount (very likely in the winter and spring), precipitation intensity, intensity of tropical and extratropical cyclones (though their frequency may decrease), and sea-level variability. The greatest uncertainty is associated with changes in annual streamflow, though it is likely that winter and spring flows will increase. Climate change alone will cause the Bay to function very differently in the future. Likely changes include: (1) an increase in coastal flooding and submergence of estuarine wetlands; (2) an increase in salinity variability on many time scales; (3) an increase in harmful algae; (4) an increase in hypoxia; (5) a reduction of eelgrass, the dominant submerged aquatic vegetation in the Bay; and (6) altered interactions among trophic levels, with subtropical fish and shellfish species ultimately being favored in the Bay. The magnitude of these changes is sensitive to the CO 2 emission trajectory, so that actions taken now to reduce CO 2 emissions will reduce climate impacts on the Bay. Research needs include improved precipitation and streamflow projections for the Bay watershed and whole-system monitoring, modeling, and process studies that can capture the likely non-linear responses of the Chesapeake Bay system to climate variability, climate change, and their interaction with other anthropogenic stressors.

Substantial differences in littoral fish community structure and dynamics in subtropical and temperate shallow lakes

Summary1. Fish play a key role in the functioning of temperate shallow lakes by affecting nutrient exchange among habitats as well as lake trophic structure and dynamics. These processes are, in turn, strongly influenced by the abundance of submerged macrophytes, because piscivorous fish are often abundant at high macrophyte density. Whether this applies to warmer climates as well is virtually unknown.2. To compare fish community structure and dynamics in plant beds between subtropical and temperate shallow lakes we conducted experiments with artificial submerged and free‐floating plant beds in a set of 10 shallow lakes in Uruguay (30°–35°S) and Denmark (55°–57°N), paired along a gradient of limnological characteristics.3. The differences between regions were more pronounced than differences attributable to trophic state. The subtropical littoral fish communities were characterised by higher species richness, higher densities, higher biomass, higher trophic diversity (with predominance of omnivores and lack of true piscivores) and smaller body size than in the comparable temperate lakes. On average, fish densities were 93 ind. m−2 (±10 SE) in the subtropical and 10 ind. m−2 (±2 SE) in the temperate lakes. We found a twofold higher total fish biomass per unit of total phosphorus in the subtropical than in the temperate lakes, and as fish size is smaller in the former, the implication is that more energy reaches the littoral zone fish community of the warmer lakes.4. Plant architecture affected the spatial distribution of fish within each climate zone. Thus, in the temperate zone fish exhibited higher densities among the artificial free‐floating plants while subtropical fish were denser in the artificial submerged plant beds. These patterns appeared in most lakes, regardless of water turbidity or trophic state.5. The subtropical littoral fish communities resembled the fish communities typically occurring in temperate eutrophic and hypertrophic lakes. Our results add to the growing evidence that climate warming may lead to more complex and omnivory‐dominated food webs and higher density and dominance of smaller‐sized fish. This type of community structure may lead to a weakening of the trophic cascading effects commonly observed in temperate shallow lakes and a higher risk of eutrophication.

Fluctuations in Abundance and Species Composition of Fishes that appear in the set net fishery in the Dadohae Marine National Park

In a joint research of the Korean Biodiversity Information Facility (KBIF), the study analyzed species composition and fluctuations in abundance of fishes caught by the set net fishery installed in the offing of Impo, Dolsando in Yeosu-si, Jeollanamdo in June and September 2008. During the study period, there were 11,180 individuals of 54 species of 39 families in 8 orders that appeared in the set net fishery in the offing of the Dadohae Marine National Park. The numbers of individuals that appeared in June and September were shown in Table 2. Among the fishes caught, the Perciformes was the dominant species with 29 species of 22 families followed by the Tetraodontiformes with 6 species of 2 families and the Pleuronectiforme with 5 species of 4 families. There appeared 3 species of 3 families of the Anguilliformes and the Beloniformes, respectively. There were 4 species of 2 families of the Clupeiformes and 3 species of 2 families of the Scorpaeniformes. There was 1 species of 1 family of the Aulopiformes. During the study period, Scomber japonicus was the dominant species with 9005 individuals followed by Trichiurus lepturus with 1500 individuals and Panpus argenteus with 184 individuals. In June, Trichiurus lepturus was dominant with 1200 individuals followed by Panpus argenteus with 150 individuals and Scomberomorus koreanus with 58 individuals. In October, Scomber japonicus was the dominant species with 9000 individuals followed by Trichiurus lepturus with 300 individuals and Scomberomorus koreanus with 45 individuals. It indicates that the dominance of a species has close relationship with water temperature because fishes migrate to feed in this season. Given the frequency of appearance, Scomber japonicus and Trichiurus lepturus most frequently appeared because they were in the middle of growing into adult fishes while the frequent appearance of Scomberomorus koreanus and Panpus argenteus, which were major species of the fishing industry, contributed to the income of fishermen. There appeared rarely seen species in the offing of Yeosu like Pelamis platurus, Rachycentron canadum (Linnaeus), Lobotes surinamensis, Kyphosus vaigiensis, Abudefduf vaigiensis and Siganus fuscescens (Houttuyn). They are subtropical fishes and seem to move here due to the warmer water affected by the global warming. Additional studies on species composition and fluctuations in abundance of fishes that appear in the set net fishery in the Dadohae Marine National Park will be continuously conducted. So, they will contribute to the increase of fishermen's income by transferring the new fish species to fishermen when newly developed rare fish species are fostered in the lab and evaluated for adaptability and growth potential. The research result will be used as basic data to secure national biological resources, and create/manage biodiversity data by building a biodiversity database network.

Biochemical properties of alligator ( Alligator mississippiensis) bone collagen

Acid-soluble collagen (ASC) and pepsin solubilized collagen (PSC) isolated and purified from alligator ( Alligator mississippiensis) bone were studied for molecular size, amino acid profile, secondary structure, and denaturation temperature by SDS-PAGE, HPLC, circular dichroism, and viscometry. Two collagen subunits, α1 and α2 were identified by SDS-PAGE. The molecular masses for α1 and α2 chains of ASC were 124 kDa and 111 kDa, respectively. The molecular masses were 123 kDa for α1 and 110 kDa for α2 chains of the PSC preparation. The molecular masses for ([α1] 2 α2) of ASC and PSC were 359 kDa and 356 kDa, respectively. The major composition of alligator bone ASC and PSC was found to be typical type I collagen. The amino acid profiles of alligator ASC and PSC were similar to amino acid profile of subtropical fish black drum ( Pogonias cromis, Sciaenidae) bone. Comparison of amino acid profiles with shark cartilage PSC, showed differences in alanine, hydroxylysine, lysine, and histidine contents. The denaturation temperatures ( T d) of alligator ASC and PSC collagen measured by viscometry were 38.1 and 38.2 °C, respectively. Thermal denaturation temperatures, measured by melting point using circular dichroism, were 37.6 and 37.9 °C, respectively. Taken together, these results suggest that alligator bone collagen may find a wide range of applications in biological research, functional foods and nutraceuticals, and biomedical and pharmaceutical research.

Quantitative assessment of total and Gram-positive aerobic bacteria in fresh and ambient-temperature-stored sub-tropical marine fish

The current study was undertaken to enumerate Gram-positive bacteria in fresh sub-tropical marine fish and determine the effect of ambient storage (25°C) on the Gram-positive bacterial count. Total and Gram-positive bacteria were enumerated in the muscles, gills and gut of fresh and stored Pseudocaranx dentex, Pagrus auratus and Mugil cephalus on tryptone soya agar (TSA) and TSA with 0.25% phenylethyl alcohol (PEA), respectively. Initial studies indicated that PEA significantly reduced total aerobic bacterial count (TABC) whereas control Gram-positive bacteria were not affected by 0.25% PEA. TABC significantly increased in all fish body parts, whereas Gram-positive aerobic bacterial count (GABC) significantly increased only in the muscles and gills during ambient storage for 15 h. The TABC of the fish species increased from 4.00, 6.13 and 4.58 log cfu g−1, respectively in the muscles, gills, and gut to 6.31, 7.31 and 7.23 log cfu g−1 by the end of storage. GABC increased from 2.00, 3.52 and 2.20 log cfu g−1 to 4.70, 5.85 and 3.36 log cfu g−1. Within each species, TABC were significantly higher in the gills compared to that of muscles and gut; however, no significant differences were found in GABC between muscles and gills. This study demonstrated the potential importance of Gram-positive bacteria in sub-tropical marine fish and their spoilage.

Elevated oxygen uptake and high rates of nitrogen excretion in early life stages of the cobia Rachycentron canadum (L.), a fast‐growing subtropical fish

Physiological energetics of cobia Rachycentron canadum were quantified for 18 to 82 days post‐hatch (dph) hatchery‐reared juveniles to better understand energy transformation and its implications in growth and survival. Mean oxygen consumption rates (; mg O2 h−1) of fish fed ad libitum and fish that were starved significantly increased with increasing wet mass (M; g), = 1·4291M0·8119 and = 1·1784M0·7833, respectively, with a significant reduction in mean metabolic rates of starved fish (19 to 27% specific dynamic action; SDA). Total ammonia nitrogen excretion rates (AMM, μmol h−1) also scaled with M and significantly decreased after starvation. Mean mass‐specific AMM and urea excretion rates are the highest reported in the literature, with urea accounting for approximately half the total nitrogen excretion measured in both fed and starved fish. Relatively high energetic rates may allow cobia to develop rapidly into pre‐juveniles and be less susceptible to predation and starvation at a comparatively early age.

Can warm climate‐related structure of littoral predator assemblies weaken the clear water state in shallow lakes?

AbstractShallow lakes, the most abundant lake type in the world, are very sensitive to climatic changes. The structure and functioning of shallow lakes are greatly impacted by submerged plants, and these may be affected by climate warming in various, contrasting, ways.Following a space‐for‐time substitution approach, we aimed to analyse the role of aquatic (submerged and free‐floating) plants in shallow lakes under warm climates. We introduced artificial submerged and free‐floating plant beds in five comparable lakes located in the temperate zone (Denmark, 55–57 °N) and in the subtropical zone (Uruguay, 30–35 °S), with the aim to study the structure and dynamics of the main associated communities.Regardless of differences in environmental variables, such as area, water transparency and nutrient status, we found consistent patterns in littoral community dynamics and structure (i.e. densities and composition of fish, zooplankton, macroinvertebrates, and periphyton) within, but substantial differences between, the two regions. Subtropical fish communities within the macrophyte beds exhibited higher diversity, higher density, smaller size, lower relative abundance of potentially piscivores, and a preference for submerged plants, compared with otherwise similar temperate lakes. By contrast, macroinvertebrates and cladocerans had higher taxon richness and densities, and periphyton higher biomass, in the temperate lakes. Several indicators suggest that the fish predation pressure was much stronger among the plants in the subtropical lakes. The antipredator behaviour of cladocerans also differed significantly between climate zones. Submerged and free‐floating plants exerted different effects on the spatial distribution of the main communities, the effects differing between the climate zones. In the temperate lakes, submerged plants promoted trophic interactions with potentially positive cascading effects on water transparency, in contrast to the free‐floating plants, and in strong contrast to the findings in the subtropical lakes.The higher impact of fish may result in higher sensitivity of warm lakes to external changes (e.g. increase in nutrient loading or water level changes). The current process of warming, particularly in temperate lakes, may entail an increased sensitivity to eutrophication, and a threat to the high diversity, clear water state.

Effect of Free-Floating Macrophyte, Azolla pinnataon Water Physico-Chemistry, Primary Productivity, and the Production of Nile Tilapia, Oreochromis niloticus (L.), and Common Carp, Cyprinus carpio L., in Fertilized Earthen Ponds

In subtropical fish ponds, many ecological processes depend on aquatic macrophytes, especially free-floating plants. The hypothesis that different free-floating macrophytes would be linked with different biological mechanisms, especially out-competing plankton, was tested here. The effect of free-floating plant, Azolla pinnatacover on water physico-chemistry, phytoplankton biomass, zooplankton abundance, and fish growth in fertilized fish ponds was compared experimentally. In 250-m2 fish ponds, Azolla plants covered 0%, 25%, 50%, or 75% of pond surface area, and the ponds were stocked with 250 Nile tilapia, Oreochromis niloticus (L.) (15.5±1.0 g), and 100 common carp, Cyprinus carpio L. (25.6±1.5 g), for 165 days. The dissolved oxygen, pH, water conductivity, phosphate, and nitrate concentrations decreased with increasing Azolla cover, especially at 50% and 75% covers. Chlorophyll a content, phytoplankton numbers and zooplankton density decreased significantly with increasing Azolla cover. Competition of Azolla plant with phytoplankton involved shading and nutrient removal from the water. There was no significant (P > 0.05) difference in the production of Nile tilapia and common carp at control and 25% Azolla cover (746 and 905 kg/ha and 706 and 874 kg/ha, respectively). The lowest fish production was obtained at 75% Azolla cover (P < 0.05). It is recommended that the fish pond could be used to culture and produce beneficial free-floating plants and fish. Moreover, free-floating macrophytes could be used to control nutrient enrichments and eutro-phication. In all cases, the cover of free-floating macrophytes should not exceed 25% of pond surface area to obtain a balanced fish culture ecosystem.

Zooplankton of a Sub-Tropical Fish Pond of High Rainfall Region of Meghalaya (N. E. India): Composition and Ecology

Zooplankton of a Sub-Tropical Fish Pond of High Rainfall Region of Meghalaya (N. E. India): Composition and Ecology

Der Fang des Tages: Scombrotoxin und Anisakis simplex als Ursache allergieähnlicher Krankheitsbilder

Introduction: By the changing attitude of eating habits, increasing import of exotic food into industrialized countries and growing worldwide tourism, also in temperate climate zones, patients with diseases elicited by marine parasites or toxins may be observed. From an epidemiological point of view the most common and important diseases are scombroid or histamine fish poisoning, anisakiasis and ciguatera. Whereas the former two may be also encountered in northern countries, ciguatera intoxications are only observed from tropical sea fish. In all three allergy-like symptoms may occur, they represent, therefore, an important differential diagnosis from IgE-mediated allergic reactions to fish and seafood allergens. Methods/patients: We present five typical cases of scombroid poisoning and a case of anisakidosis, and discuss the characteristics, elicitors, diagnostic criteria and differential diagnosis of these disorders. Results and discussion: Scombroid poisoning is an intoxication from biogene amines that are formed due to inadequate storing and insufficient freezing after the catch. Particularly the odor- and tasteless histamine, possibly together with other substances or cofactors, may induce acute allergy-like symptoms such as flush, pruritus, urticaria and gastrointestinal symptoms. The reaction is self-limiting, it lasts a few hours and it usually results in complete recovery. Anisakidosis or anisakiasis is caused by the fish parasite Anisakis simplex. The acute parasitic infestation of the accidental human host by live parasites results in acute severe abdominal pain, caused by an eosinophilic inflammation in the gastrointestinal wall, which subsides within a few hours after the death of the worm. In sensitized individuals exposure to undercooked fish infested by anisakis elicits allergic symptoms ranging from urticaria, angioedema to dyspnoe and life-threatening anaphylactic shock. Some authors have reported a combination of parasitic and allergic reaction called gastroallergic anisakiasis. Ciguatoxins are lipid-soluble toxins known as ciguatoxins accumulated in the muscles of carnivorous subtropical and tropical fish. Ciguatoxins arise from biotransformation in the fish from gambier-toxins produced by Gambierdiscus toxicus, a marine dinoflagellate that lives on macroalgae in corals. The toxins and their metabolites are concentrated in the food chain when carnivorous fish prey on smaller herbivorous fish. More than 400 species offish can be vectors of ciguatoxins. Symptoms include gastrointestinal, neurological and cardiovascular disturbances, in severe cases paralysis, coma and death may occur. Symptoms subside typically in few days but may persist for months or years, or recur periodically. In the differential diagnosis toxins from seafood such as saxatoxin and brevitoxin have to be considered. Conclusions: In patients with suspected allergic symptoms after the consumption of fish or seafood, the differential diagnosis should include disorders from marine toxins or parasites, which may elicit allergy-like symptoms and signs. This permits an exact diagnosis, therapy and adequate preventive measures.

Biomonitoring of ciguatoxin exposure in mice using blood collection cards

Ciguatera is a human food poisoning caused by consumption of tropical and subtropical fish that have, through their diet, accumulated ciguatoxins in their tissues. This study used laboratory mice to investigate the potential to apply blood collection cards to biomonitor ciguatoxin exposure. Quantitation by the neuroblastoma cytotoxicity assay of Caribbean ciguatoxin (C-CTX-1) spiked into mice blood was made with good precision and recovery. The blood collected from mice exposed to a sublethal dose of Caribbean ciguatoxic extract (0.59 ng/g C-CTX-1 equivalents) was analyzed and found to contain detectable toxin levels at least 12 h post-exposure. Calculated concentration varied from 0.25 ng/ml at 30 min post-exposure to 0.12 ng/ml at 12 h. A dose response mice exposure revealed a linear dose-dependent increase of ciguatoxin activity in mice blood, with more polar ciguatoxin congeners contributing to 89% of the total toxicity. Finally, the toxin measurement in mice blood exposed to toxic extracts from the Indian Ocean or from the Pacific Ocean showed that the blood collection card method could be extended to each of the three known ciguatoxin families (C-CTX, I-CTX and P-CTX). The low matrix effect of extracted dried-blood samples (used at 1:10 or 1:20 dilution) and the high sensitivity of the neuroblastoma assay (limit of detection 0.006 ng/ml C-CTX-1), determined that the blood collection card method is suitable to monitor ciguatoxin at sublethal doses in mice and opens the potential to be a useful procedure for fish screening, environmental risk assessment or clinical diagnosis of ciguatera fish poisoning in humans or marine mammals.

Warming and exponential abundance increase of the subtropical fish Capros aper in the Bay of Biscay (1973–2002)

The exponential abundance increase of a sub-tropical species, boarfish ( Capros aper), as well as the sea bottom temperature increase in the continental shelf of the Bay of Biscay (France) over the three last decades are reported. This species was rare in the seventies and is now a dominant one. This is a small bathy-demersal, probably short-lived species with few predators (probably because of the presence of strong spines) and not exploited by fisheries. In the same time, a significant temperature increase in the bottom waters is observed during the breeding season of this population. The boarfish abundance increase is related to the warming, its ability to invade and the absence of predators as well as the absence of fishing. To cite this article: F. Blanchard, F. Vandermeirsch, C. R. Biologies 328 (2005).

Northward range extensions of some mesopelagic fishes in the Northeastern Atlantic

In a period mainly from 1995 to 1998, 19 species of southern temperate and subtropical mesopelagic fish have been caught in Norwegian blue whiting, Micromesistius poutassou (Risso), surveys in the Rockall Trough area. Six of the species have not previously been recorded that far north, and the other 13 only rarely in adjacent waters. The species were of the following families: Stomiidae (four species), Microstomatidae (one species), Bathylagidae (one species), Opisthoproctidae (one species), Myctophidae (four species), Evermannellidae (one species), Nemichthyidae (one species), Derichthyidae (two species), Melanonidae (one species), Melamphaidae (one species), and Chiasmodontidae (two species). We discuss whether these range extensions are real and attributable to the recent ocean warming, or only apparent, caused by increased sampling effort.

Changes in the Cellular and Organismal Stress Responses of the Subtropical Fish, the Indo-Pacific Sergeant, Abudefduf vaigiensis, due to the 1997–1998 El Niño/Southern Oscillation

There are accumulating reports showing that the El Nino/Southern Oscillation (ENSO) has a significant effect on the population dynamics of marine fishes. However, the influence of ENSO on the physiology of fishes, as possible components of those ecological changes in fish populations, is not fully understood. This study investigated the cellular, physiological, and organismal stress responses in a wild fish population under natural thermal stress. The sea surface temperature at the subtropical ocean of Okinawa, Japan, was the highest in the last 10 years (>32°C) during the summer of 1998 with a strong ENSO. To examine the effects of those unusually warm ocean temperatures on fish, we compared tissue 70-kDa heat shock protein (HSP70) levels and growth rates between the ENSO summer of 1998 and the normal summer of 1999 in a common fish species in Okinawa, the Indo-Pacific sergeant, Abudefduf vaigiensis. We also conducted a complementary heat shock experiment in the laboratory. The field collected Indo-Pacific sergeant had significantly higher muscle HSP70 levels in 1998 than 1999. Higher muscle HSP70 and plasma cortisol levels were observed at 32°C than at 28°C in the laboratory heat shock experiment, indicating that the highest summer ocean temperature in 1998 was sufficient for the fish to up-regulate the cellular and physiological stress responses. In support of this effect, otoliths showed slower growth rates of the fish during the summer of 1998; this may reflect the significant energetic cost of these stress responses.

Biota, palaeoenvironments and biostratigraphy of continental Oligocene deposits of the South German Molasse Basin (Penzberg Syncline)

Six charophyte, 13 mollusc, four ostracod and nine fish otolith taxa are taxonomically described, and one fruit, one seed and two foraminiferal taxa are briefly noted from the Lower Cyrena Beds and the Lower Coloured Molasse of the Sindelsdorf section near Penzberg (approximately 50 km south of Munich). Our palaeoecological and lithological data from the Lower Cyrena Beds suggest a delta plain with lagoons, estuaries, slowly flowing rivers, lakes and swamps. Faunal and floral elements of the Lower Coloured Molasse indicate lacustrine environments. The gastropod Tympanotonos and the tropical to subtropical fish fauna (Eleotridae, Ambassidae and Cyprinodontidae) suggest a warm, at least subtropical climate. Furthermore, Tympanotonos suggests comparisons with Recent molluscan faunas of the mangrove swamps of the West African coast, and thus hints at mangrove vegetation bordering the coasts of the Upper Bavarian Molasse Sea. A biostratigraphical classification for the Oligocene Molasse deposits of the Penzberg Syncline is established for the first time based on otoliths and charophytes. The Lower Cyrena Beds are attributed to the newly defined otolith zone OT‐O1/2 and probably correspond to the oldest part of the Chara microcera Zone. The lowermost part of the Lower Coloured Molasse can be correlated both with otolith zone OT‐O2 and the Chara microcera Zone. The Sindelsdorf section lies within the Rupelian–Chattian transition zone and thus the chronostratigraphic age is approximately 29–28 Ma.

MARINE FISHES NEW TO CONTINENTAL UNITED STATES WATERS, NORTH CAROLINA, AND THE GULF OF MEXICO

Abstract Along the southeastern coast of the United States, hardground systems support a high diversity of sub-tropical and tropical fishes. Many of these hardgrounds occur in deep (ca. ≥ 50 m) waters and their fauna is still poorly described; however, with concentrated sampling in these deeper areas, new records of fishes continue to emerge. In the northeastern Gulf of Mexico and off North Carolina, we used the Johnson-Sea-Link submersible, remotely operated vehicles, trawling gear, and angling gear to sample deep reef systems (38–248 m). We document five records of fishes new to continental United States waters, including Liopropoma aberrans, Parasphyraenops incisus, Lipogramma regia, Apogon gouldi, and Prognathodes guyanensis. We also report range extensions for eleven species: Gymnothorax hubbsi, Gymnothorax vicinus, Lepophidium staurophor, Cypselurus comatus, Liopropoma mowbrayi, Serranus annularis, Rypticus saponaceus, Caranx lugubris, Prognathodes aculeatus, Centropyge argi, and Canthigaster jamest...

Amylolytic activity in fish intestinal mucosa: temperature effects

The activity, temperature characteristics and energy of activation of amylolytic enzymes in the intestinal mucosa were studied in six species of fish living in a boreal zone [burbot ( Lota lota L.), northern pike ( Exos lucius L.), perch ( Perca fluviatilis L.), bream ( Abramis brama L.), roach ( Rutilis rutilis L.), and carp ( Cyprinus carpio L.)] and in three species from tropical and subtropical areas [pilchard ( Sardina pilchardus W.), jack mackerel ( Trachurus trecae C.) and round sardinella ( Sardinella aurita V.)]. The amylolytic activity correlated with the feeding habits: it was essentially lower in predators. The enzyme activity at low temperature, relative to the maximal activity, was correlated with the natural environmental temperature where the species lived. At low temperature the relative activity was higher in boreal fish than in tropical and subtropical fish. We found a breakpoint in the Arrhenius plots in all fish species, except for jack mackerel. The energy of activation in predators decreased below the breakpoint in the low-temperature region. The energy of activation in benthophages of the Aral–Ponto–Caspian area was lower at higher temperatures above the breakpoint. A reduction in activation energy in the range of physiological temperatures might indicate adaptation to the environmental temperature.