Validating annulus formation and examining the potential use of pectoral spines for age determination in Aristotle’s catfish (Silurus aristotelis)

The potential use of pectoral fin spines for ageing purposes was examined in Aristotle’s catfish (Silurus aristotelis) and validated for growth proportionality and growth mark periodicity. Monthly samples (n = 436, total length range: 11.10–36.70 cm) were collected in Lake Pamvotis, Greece from November 2002 to December 2003. Marginal increment analysis showed that the spine width (SW) radius grew proportionally to total body length (TL) (TL = 9.581 + 6.83SW, r² = 0.66, n = 431, P < 0.01), and was at a minimum in January and February, indicating a single growth mark formation per year (i.e. annulus). Further analyses showed that the morphometric characteristics of the spines did not differ significantly (r² > 0.80 in all cases) when removed from one side of the fish or the other. The procedure was based on individuals no older than 5 years of age; extrapolation to higher age classes may be critical.     

Biological traits of rare males in the population of Carassius gibelio (Actinopterygii: Cyprinidae) from Lake Pamvotis (north‐west Greece)

The gynogenetic population of Prussian carp Carassius gibelio in Lake Pamvotis (north‐west Greece) included a small percentage of males (2–3%). Cytogenetic analysis revealed heterogeneity of the population at the ploidy level: all females were triploid (modal chromosome number 156–162 chromosomes) while the males were either triploid (modal number 156–158 chromosomes) or tetraploid (modal number 200–214 chromosomes). Morphometric analysis revealed significant differences in body shape among these three groups. The males were more slender than females, while the triploid males could be discriminated from the tetraploid by the morphology of their caudal peduncle. The males attained a significantly lower asymptotic standard length (L_S) (25·04 cm) than females (29·75 cm) and had lower exponent b of the L_S and mass relationship. Under laboratory conditions, intraspecific crossings of C. gibelio males with females could give viable all‐female offspring; in comparison with goldfish Carassius auratus males, the fertility of the C. gibelio males was generally reduced but remained highly variable among individuals.     

Life‐history characteristics of the large Amazonian migratory catfish Brachyplatystoma rousseauxii in the Iquitos region,Peru

The main life‐history traits of the dorado Brachyplatystoma rousseauxii, a large Amazonian catfish undertaking the largest migration known for a freshwater fish species (from the nursery area in the estuary of the Amazon to the breeding zones in the head waters of the western Amazon basin close to the Andes), were determined from a 5 year sampling of >15 000 specimens in the Peruvian Amazon. The breeding season occurred during the falling and low‐water periods, which is hypothesized to be an adaptation to maximize the chances of young stages to reach the estuary. The size at first sexual maturity was slightly larger for females than males, c. 91 and 83 cm standard length (L_S), respectively. Both males and females reproduce for the first time at >3 years old. The fecundity per spawning event ranged from 481 734 to 1 045 284 oocytes for females weighing 25 and 34 kg, respectively. Seasonal variations of body condition were similar among sexes, but differed between immature specimens that had a higher condition during the low‐water period and lower condition during rising waters, and mature individuals that showed the opposite pattern. The growth characteristics were estimated by L_S frequency analysis. For females, the best fitting models gave a mean birth date in August, during the height of the breeding cycle, with the following von Bertalanffy growth function parameters: L_S∞ = 153·3, K = 0·29 and t₀ =– 0·37 years. For males, the best fitting model gave a mean birth date in July, also during the height of the breeding period, with L_S∞ = 142, K = 0·30 and t₀ =– 0·36 years. At a given age, females were systematically larger than males and the size difference increased with age. The largest females sampled (148 cm L_S) was 11 years old and the largest male (134 cm L_S) was 9 years old. The mortality estimates were higher for males total (Z) = 1·34, natural (M) = 0·52 and fishing (F) = 0·82 than for females (Z = 0·98, M = 0·50, F = 0·48). The life‐history patterns of B. rousseauxii are discussed in light of the available knowledge about this species and the understanding of its complex life cycle.     

Life‐history traits of Aphanius danfordii (Boulenger, 1890) (Pisces: Cyprinodontidae), endemic to Kızılırmak Basin (Turkey)

The life‐history traits of Aphanius danfordii in Hirfanl? Reservoir were studied on the basis of 2252 specimens caught between April 2008 and April 2009. Maximum age was determined as five years for both sexes. The overall sex ratio of males to females was 1 : 1.21; however, this ratio varied by age and season. Mean total length at age data derived from scale readings were used to estimate growth. The von Bertalanffy growth parameters were: L_∞ = 126.63 mm, K = ?0.09, t₀ = 2.35 for females; and L_∞ = 61.2 mm, K = ?0.19, t₀ = 2.76 for males. The gonadosomatic index (GSI) values indicated spawning to be from May to September. Absolute fecundity varied from a minimum of 143 eggs for age one to a maximum of 698 eggs for age five. Relationships between fecundity–length and fecundity–weight were described by the equations: F = 0.0002 TL^3.3222 and F = 36.032 W^1.0053, respectively. The equation of the relation between absolute fecundity and age was F = 25.372 t^1.2343.     

Diet and feeding habits of Economidichthys pygmaeus (Perciformes: Gobiidae) in Lake Pamvotis,NW Greece

The purpose of the study was to define the diet composition, feeding preferences, seasonal, size and sex related changes in diet, feeding strategy and diel cycle of Economidichthys pygmaeus. Important features of the overall feeding patterns of the goby include (i) feeding activity, (ii) bottom habits and (iii) consumption of food items to identify the dietary breadth. Stomach contents of 533 specimens, 13.42–48.65 mm total length (TL), collected by hand net (2 mm mesh size) from October 2006 to September 2007 were analyzed. The percentage of 76 empty stomachs (14.26%) did not vary significantly with season. The food composition suggested that the goby is a carnivorous fish. Prey items identified in the stomachs belonged to four major groups: Crustaceans, Insects, Mollusca and Plants. Copepods were the most important (%IRI = 57.51), especially in fish larger than 23 mm TL. Chironomids (%IRI = 43.23) constituted the main prey for fish <23 mm TL. Diet composition showed little seasonal variation. Copepoda dominated the diet in autumn and winter (43.4%; 82.4%) and were replaced by Chironomidae larvae in spring (39.7%) and summer (47.7%). During the reproductive season, large males show a narrow food spectrum as opposed to large females, reflecting the different activity pattern exhibited by males and females during the breeding season, since the former supports parental care. According to the modified Costello graphical method, specialist individuals form the goby population that feeds on two preferential prey types (e.g. Copepods, Chironomids). Nevertheless, they consume some occasional prey (e.g. Cladocera, Insects, Gastropods). The species foraged chiefly at night and early morning, during lower light intensity. The highest feeding activity recorded at night (02.00 hours) and during early morning (08.00 hours) could be related to the cryptic behaviour displayed by the species.     

The diet of Horabagrus brachysoma (Gunther), an endangered bagrid catfish from Lake Vembanad (South India)

A stomach content analysis of Horabagrus brachysoma from Lake Vembanad, South India, showed that this species was omnivorous and euryphagous, with few qualititative differences in the diet among size classes. Feeding rates changed over the course of a year in response to environmental change associated with the monsoon.     

Reproductive ecology of the Far Eastern catfish, Silurus asotus (Siluridae), with a comparison to its two congeners in Lake Biwa, Japan

Spawning activity of the catfish, Silurus asotus, takes place in temporary water (rice fields) from early evening to midnight, generally in connection with rainfall, from late April to late August. Spawning of the catfish was correlated with hydrographic parameters dependent on rainfall: daily precipitation, turbidity, water depth, and water temperature. The spawning habits of the catfish, and in particular the use of temporary waters such as rice fields that become submerged after rainfall or by irrigation, are presumed to be adaptations to the Asian monsoon climate with a pronounced rainy season. The apparent sex ratio of the catfish was extremely biased toward females. Intraspecific variation in the reproductive ecology, particularly mating behavior, of this species is observed among local populations. Factors that may have caused this variation are discussed in the context of a comparison of mating behavior, reproductive environment, and sex ratio between the Lake Biwa population of S. asotus and other conspecific populations, as well as two other species of silurid catfish that occur in the Lake Biwa drainage, S. biwaensis and S. lithophilus.     

Life‐history traits of the leatherjacket Meuschenia scaber,a long‐lived monacanthid

The present study describes the age and growth of the leatherjacket Meuschenia scaber, a common Australasian monacanthid and valued by‐catch of the inshore bottom trawl fishery in New Zealand. Age was determined from the sagittal otoliths of 651 individuals collected between July 2014 and March 2016 in the Hauraki Gulf of New Zealand. Otolith sections revealed alternating opaque and translucent zones and edge‐type analysis demonstrated that these are deposited annually. Meuschenia scaber displayed rapid initial growth, with both males and females reaching maturity in 1–2 years and 50% of both sexes matured at 1·5 years. Maximum age differed substantially between the sexes, at 9·8 years for males and 17·1 years for females. Growth rate was similar between sexes, although males reached greater mass at age than females in the early part of the lifespan. The length–mass relationship differed significantly between the sexes, with males displaying negative allometric growth and females isometric growth. Female condition was highest in July, declined in August with the onset of spawning and showed a slight peak in January and February, immediately following the spawning season. This study substantially extends the maximum longevity recorded for monacanthids, although males had much shorter lifespans and higher mortality, than females.     

Life‐history traits of the stone loach Barbatula barbatula

The life‐history tactics of the stone loach Barbatula barbatula were studied in a Mediterranean‐type climate stream (Matarranya River) located in the Ebro River basin (north‐east Spain). Maximum observed ages were 2+ years in both sexes (1% of individuals), although only 0+ and 1+ year age groups were well represented. It is the lowest longevity reported for this species in its entire distribution. The seasonal growth period started in June and continued until November, but the pattern observed was different to northern populations. Barbatula barbatula in the Matarranya River was a multiple spawner, releasing small batches of oocytes between April and June. The fecundity of females was higher and the size of oocytes smaller in 1984 than in 1985. The relative fecundity (number of ripening and ripe oocytes g^?1 of fish) was lower than in northern European populations. The role of the particular environmental conditions of a Mediterranean stream was discussed in relation to the life‐history tactics of B. barbatula.     

A revision of the fossil Canidae (Mammalia) of north‐western Africa

Abstract: The fossil record of the Canidae in North‐western Africa begins near the Miocene–Pliocene boundary with a form close to Nyctereutes, a genus best known in the late Pliocene of Ahl al Oughlam. This site yields two other canids. Vulpes hassani sp. nov. is a small fox, probably ancestral to the modern V. rueppelli, recorded from the Middle Pleistocene onwards. Lupulella paralius sp. nov. is a primitive jackal that probably belongs to the clade of modern African jackals. In the middle Pleistocene, the most common canid is Lupulella mohibi sp. nov., remarkable by its Nyctereutes‐like dentition and primitive skull‐features. These are all endemic forms, but V. vulpes and C. aureus, of northern origin, appear in the course of the middle Pleistocene. Lycaon has a sparse record in the middle and late Pleistocene.     

Life‐history consequences and disease resistance of western tent caterpillars in response to localised,herbivore‐induced changes in alder leaf quality

1. Plants can respond to herbivore damage with phenotypically plastic changes in quality that negatively affect herbivores and prevent subsequent attack – induced defences. 2. The present study tested whether trees respond to herbivory with localised induction, and whether life‐history traits and disease resistance of an insect herbivore are altered on induced branches of the trees. 3. The influences of localised, within‐branch, herbivore‐induced changes in red alder trees (Alnus rubra Bong.) on fitness characteristics of western tent caterpillars (Malacosoma californicum pluviale Dyar) were evaluated. In the field, randomly selected branches of trees were infested with tent caterpillar larvae and the adjacent branches were maintained as non‐infested controls. In the laboratory, larvae were fed leaves from either induced or non‐induced branches through to adult emergence. A second cohort of larvae was challenged with a viral pathogen to compare their disease susceptibility on induced versus non‐induced foliage. 4. Herbivore‐induced, localised responses of damaged branches reduced leaf quality for growth and the fecundity of female western tent caterpillars, but not that of males. Larvae fed induced leaves had a higher survival overall and a reduced mortality due to unidentified non‐viral pathogens than did their counterparts on non‐induced leaves. However, there was no influence of leaf quality on baculovirus‐induced mortality. 5. These findings suggest that localised induced changes in leaf quality could potentially influence populations of tent caterpillars in contradictory ways by reducing their growth rate and fecundity to a modest degree, while improving their survival and resistance to unidentified non‐viral pathogens to a larger extent.     

The Holocene history of vegetation and settlement at the coastal site of Lake Voulkaria in Acarnania, western Greece

A palynological investigation of a Holocene profile from Lake Voulkaria, western Greece, was carried out as a contribution to the environmental history of the coastal area of northwestern Acarnania and the Classical city of Palairos. It shows that deciduous oaks dominated the natural vegetation of the area throughout the Holocene. Until ca. 7000 B.C. Pistacia occurred abundantly, while other evergreen woody taxa were rare. At ca. 6300 B.C. an expansion of Carpinus orientalis/Ostrya can be observed. Around ca. 5300 B.C. spreading of Erica indicates a change to a drier climate and/or first human impact. Since ca. 3500 B.C. an increase of evergreen shrubs now clearly indicates land-use. The foundation of the Classical city of Palairos led to a temporary expansion of Phillyrea maquis. Within this period, molluscs of brackish water indicate the use of the lake as a harbour after the construction of a connection to the sea. The deciduous Quercus woodland recovered when human impact decreased in the area, and lasted until modern times.     

Life history of a wide‐ranging deepwater lantern shark in the north‐east Atlantic,Etmopterus spinax (Chondrichthyes: Etmopteridae), with implications for conservation

In this paper, the population biology of the velvet belly lanternshark Etmopterus spinax was studied and life‐history coefficients determined. Age was estimated from sections of the second dorsal spine and validated by marginal increment analysis. Males attained a maximum age of 8 years while 11 year‐old females were found. Several growth models were fitted and compared for both size‐at‐age and mass‐at‐age data, showing that even though this is a small‐sized species, it has a relatively slow growth rate. This species matures late, specifically at 49·6 and 42·5% of the maximum observed ages for males and females, respectively. It has a low fecundity, with a mean ovarian fecundity of 9·94 oocytes and a mean uterine fecundity of 7·59 embryos per reproductive cycle. This species seems to have a long reproductive cycle, and even though no conclusive data were obtained, a 2–3 year cycle is possible. The estimated coefficients indicate that this species has a vulnerable life cycle, typical of deepwater squalid sharks. Given the high fishing pressures that it is suffering in the north‐east Atlantic, this fish may already be facing severe declines or in risk of facing them in the near future.     

Life‐history strategies of Manipora amicarum Sinclair, 1955 (Tabulata; Upper Ordovician; southern Manitoba,Canada)

Based on detailed study of transverse serial sections, we recognize various modes of corallite increase in a multichain cateniform coral, Manipora amicarum from the Selkirk Member, Red River Formation, in Manitoba. One type of axial increase and four types of lateral increase involve normal, undamaged corallites, and one type of axial increase and one type of lateral increase occur during recovery processes of corallites damaged by sediment or bioclast influx. All but one of these types of increase are comparable to those in a single‐chain coral, Catenipora foerstei, which we previously documented from the same stratigraphic unit and locality. In M. amicarum, the formation of double ranks and agglutinated patches of corallites by normal corallites, and by recovery processes following corallite damage, is common and presumably genetically controlled. Agglutinated patches originate differently in C. foerstei, occurring sporadically or temporarily in only some coralla. Average annual vertical corallum growth in M. amicarum, as indicated by cyclic fluctuations of tabularial area, is higher than in C. foerstei, which has comparatively smaller corallites. In general, annual growth in M. amicarum is positively correlated with average tabularial area, negatively correlated with frequency of damaged corallites, and is not related to the frequency of corallite increase. In C. foerstei, however, there is a positive association between annual growth rate and the frequency of increase by damaged corallites, related to episodes of sediment or bioclast influx probably generated by storms. In comparison with C. foerstei, M. amicarum has a low frequency of corallite termination and extensive partial mortality is rare. It seems that the relatively rapid overall vertical corallum growth in M. amicarum was effective for protecting the coral from unfavourable situations, possibly by maintaining the growth surface higher above the substrate than in C. foerstei. Although these two species show many similarities in the types of corallite increase, their reactions and strategies in relation to physical disturbance were quite different.     

Phylogeographical patterns of two closely related desert shrubs,Nitraria roborowskii and N. sphaerocarpa (Nitrariaceae), from arid north‐western China

To investigate the influence of climate aridification and oscillations on the genetic diversity and evolutionary processes of organisms in the Quaternary in north‐western China, we selected Nitraria roborowskii and N. sphaerocarpa and examined the geographical apportionment of genetic variation in their vast range. In the study, 21 plastid haplotypes were identified in N. roborowskii based on two plastid DNA regions. We found significant genetic differentiation between populations in both N. roborowskii and N. sphaerocarpa. We also found similar phylogeographical patterns of allopatric divergence and regional range expansion in both species, but the degree of allopatric divergence in N. roborowskii was lower. Finally, areas to the south of the Alxa Desert, the Hexi Corridor and Ningxia Province were identified as possible refugia for N. roborowskii.