Distribution and abundance of fish in the southwest of Caspian Sea coastal waters

This study was carried out in southwestern Caspian Sea coastal area to elucidate demersal bony fishes distribution and abundance. Twenty two species were found in shore line, which belong to 6 families. In deeper waters down to 7 meters only 5 species of Gobiidae and 1 species of Syngnathidae were identified. Two species Neogobius caspius and N. pallasi were the main components of demersal fishes; however in some regions Rutilus caspicus, Rutilus kutum and Liza spp. were dominated. Most places were dominantly occupied by Atherina boyeri, which had the highest abundance among the pelagic fishes. Conversely, the Ponticola gorlap, N. melanostomus and Proterorhinus nasalis showed the lowest abundances (less than 1 ind./100 m²). Benthophilus stellatus and P. nasali had the lowest niche overlaps with other species. Both of these two species and P. gorlap are suggested to be classified as endangered or vulnerable species based on their low abundance. The distribution of Syngnathus abaster depends on algae, while algae grow up into the stony construction of the coastal line. A negative insignificant correlation was observed between pelagic and demersal fish abundances. The commercial fisheries data of 76 beach seines in our study area during 2002–2013 was compared with our results on fish abundance and species composition. More than 93% of total fish catch constituted Liza spp. and Rutilus kutum. The relationship between the abundance and distribution of the studied species, and the restocking activities performed by Iranian fisheries organization are discussed. The high abundance and distribution of small size fish in tidal zone could be related to the distribution of crustacean, which provide a good source of food for these fish species.     

Authentication of five <Emphasis Type="Italic">Barilius</Emphasis> species from Indian waters using DNA barcoding

Authentic identification of fish species is essential for conserving them as a valuable genetic resource in our environment. DNA barcoding of living beings has become an important and ultimate tool for establishing their molecular identity. Among cyprinids, Barilius is an important genus having nearly 23 species in Indian region whose morphological identification is often difficult due to minute differences in their features. Five species collected from Indian waters and primarily identified as Opsarius bakeri (syn. Barilius bakeri), B. gatensis, B. vagra, B. bendelisis and B. ngawa were authenticated by their DNA barcoding based on mitochondrial COI gene sequences. Five individuals of each species were taken for barcode preparation by COI gene sequencing which yielded one barcode for B. ngawa, two barcodes each for O. bakeri, B. gatensis, B. bendelisis and three barcodes for B. vagra. The order of inter and intra-specific variation was estimated to know a preliminary status of variation prevailing in these cold stream fish species significant for evolution and conservation of these valued species of our ichthyofauna. Average variation within genera was found to be 13.6% with intra-specific variation ranging from 0.0% (B. ngawa) to 0.6% (B. gatensis). These distance data are in the same order found by various researchers globally using COI barcode sequences in different fish species. Phylogenetic relatedness among Barilius species and some other cyprinids validate their status of individual species as established by conventional taxonomy.     

Diversity of fish species in suichuan river and shushui river and conservation value,China

Based on the data collected from the Suichuan and Shushui Rivers, both tributaries of the Ganjiang River between April and July of 2015, the fish species identified were classified into 68 and 46 species, 14 and 12 families in the Suichuan River and Shushui River respectively. Cyprinidae is the most common family that accounts for 52.9% and 58.7% in the total number of fish species in the Suichuan River and Shushui River, respectively. The dominant species were Pseudohemiculter dispar, Squalidus argentatus, Silurus asotus and Leptobotia elongate for the Suichuan River and Squalidus argentatus, Acrossocheilus parallens, Pseudohemiculter dispar, Silurus asotus, Pelteobagrus fulvidraco, Acrossocheilus fasciatus and Zacco platypus for the Shushui River. The diversity of fish species showed more abundant and diverse for the Suichuan River. The composition of ecotype of fish indicated the rich diversities of ecotype in both the Suichuan and Shushui Rivers. The tributary (Suichuan River) and main stream of the Ganjiang River demonstrated a highly fauna similarity and the fish resources indicated its significance to maintain the fish diversity in the middle of the Ganjiang River and its benefits to the existence of the fish species in mountain streams. Dam construction, sand excavation and heavy metal pollution are the most significant threat to fish diversity and ecosystem functioning in Ganjiang River basin. In order to protect fish diversity and fisheries more effectively, relevant laws should be strengthened and conservation areas should be established for the survival of freshwater fish species.     

Fish assemblage structure in an estuary of the Atlantic Forest biodiversity hotspot (southern Brazil)

We described the fish assemblage in the estuary of the Guaraguaçu River (one of the largest tributaries of the Paranaguá Bay Estuary, located within Brazil’s Atlantic Forest Biosphere Reserve) from June 2005 to May 2006, and assessed the seasonal and spatial effects of abiotic environmental attributes on the fish assemblage structure. Despite some oscillations in salinity, the upper and lower estuaries had year-round persistent oligohaline and polyhaline conditions, respectively. Despite high species richness (55 species), the Guaraguaçu River Estuary fish community contains a few dominant taxa; 11% of the richness accounts for >60% of its density and biomass. The most abundant species (in terms of both biomass and density) was Atherinella brasiliensis. Species whose densities were most strongly associated with the upper estuary were Centropomus parallelus, Ctenogobius schufeldti, Eucinostomus melanopterus, Platanichthys platana, Trinectes paulistanus, and Eugerres brasilianus. Those whose densities were most strongly associated with the lower estuary were A. brasiliensis, Sphoeroides greeleyi, Eucinostomus argenteus, Sphoeroides testudineus, Diapterus rhombeus, and Harengula clupeola. Throughout the year, canonical correspondence analysis identified: (1) the pattern of horizontal stratification of salinity along the river as being the most important variable for explaining most of the fish fauna structure; and (2) a strong relationship between the fish fauna and the salinity gradient along the estuary. Analysis of similarity further confirmed that each estuarine zone supports a year-round persistent and relatively homogeneous fish species assemblage. Total mean density and biomass remained constant over time in each estuarine habitat, but density shifted in the most abundant species, which appears related to recruitment patterns. Such species and abundance persistence likely occurs because seasonal rainfall-induced changes in river discharge are not sufficient to significantly shift runoff and salinity and thus fish assemblage structure (species composition, density and biomass) along the estuary. Such a lack of seasonal fish fauna movement as a response to changes in river flow contrasts with other estuarine systems around the world.     

Rare species of cyclostomata and fish in the Upper Oka basin and within Kaluga oblast

The species list of fish of the Upper Oka basin is verified. Data on biology of rare species are presented (western brook lamprey Lampetra planeri, sterlet Acipenser ruthenus, bystryanka Alburnoides bipunctatus rossicus, asp Aspius aspius, undermouth Chondrostoma variabile, bitterling Rhodeus sericeus, and fresh-water sculpin Cottus gobio koshewnikowi). Their morphological characters, distribution in the Upper Oka basin relative abundances of these species, and its changes during recent decades are also commented.     

Follower fish of the goldspotted eel <Emphasis Type="Italic">Myrichthys ocellatus</Emphasis> with a review on anguilliform fish as nuclear species

In a nuclear-follower fish foraging association, the follower benefits from food uncovered or flushed out when the nuclear fish disturbs the bottom, while nuclear species generally do not seem to be benefiting. Among nuclear species, eels (anguilliform fish) are known to be one of the most represented groups. Here we investigated the frequency and time duration of foraging associations among the goldspotted eel Myrichthys ocellatus and reef fish in a subtropical marginal reef. In addition, we reviewed nuclear eel species and their followers described in the literature. From a total of 211 goldspotted eels observed, seven follower species were recorded in 19% of the samples. The average time of the following associations per species ranged from 40 to 190 s. Four species were reported for the first time as M. ocellatus followers (Bodianus rufus, B. pulchellus, Stephanolepis hispidus, and Serranus baldwini) and three of them have never been reported in the literature as eel followers (B. pulchellus, S. hispidus, and S. baldwini). The literature describes 13 eel species acting as nuclear for 66 fish species, represented mainly by groupers and sea basses. The size of the eel was not correlated with the size of its follower and neither with the number of described follower species. The nuclear role of eels is likely to be an important component of the trophic ecology of small and medium-sized macrocarnivore fish.     

Different ecological conditions support individual specialization in closely related,ecologically similar species

Individual generalist predators often have more specialized diets than their populations do. Individual specialization (IS) is influenced by ecological opportunity, intraspecific competition, and interspecific competition, although the effects of these parameters are inconsistent across studies. We investigated IS in five species of frogs and toads, Anaxyrus americanus, A. fowleri, Lithobates catesbeianus, L. clamitans, and L. sphenocephalus. We used the natural history and ecology of each species to predict which parameters would influence IS. Our predictions were supported for some species but not others. We predicted IS would be positively influenced by resource diversity in all species, but this prediction held for only three species, with the relationship significant in A. fowleri and L. catesbeianus and marginally significant in A. americanus. We also predicted that interspecific competition would have a negative relationship with IS in L. clamitans because L. catesbeianus is competitively superior to L. clamitans and likely to suppress its foraging options. This prediction was upheld. Finally, we predicted that IS in A. americanus, A. fowleri, and L. clamitans would be influenced by intraspecific competition. However, IS was not influenced by intraspecific competition in any species, a surprising result given that intraspecific competition has traditionally been assumed to be the ecological parameter with the strongest effects on IS. Many previous studies did not simultaneously consider all three ecological parameters, which may have increased the apparent importance of intraspecific competition for IS. Our results revealed that the ecological parameters affected IS differently even across closely related and ecologically similar species, and demonstrated that these differences are sometimes predictable based on natural history. This study also suggests that sympatric ecological speciation based on IS may be rare because the ecological parameters driving IS are inconsistent across species, and the strength of their effects on intraspecific diet variation varies in space.     

Ticks (Acari: Ixodidae) in the Serra da Canastra National Park in Minas Gerais,Brazil: species,abundance, ecological and seasonal aspects with notes on rickettsial infection

The Cerrado Biome is the second largest in Brazil covering roughly 2 million km², with varying features throughout its area. The Biome is endangered but it is also source of animal species for rural, green urban and degraded rainforest areas. Ticks are among Cerrado species that establish at anthropogenic sites and although information about them is steadily increasing, several features are unknown. We herein report tick species, abundance and some ecological relationships within natural areas of the Cerrado at higher altitudes (800–1500 m) within and around Serra da Canastra National Park, in Minas Gerais State Brazil. In total of 1196 ticks were collected in the environment along 10 campaigns held in 3 years (2007–2009). Amblyomma sculptum was the most numerous species followed by Amblyomma dubitatum and Amblyomma brasiliense. Distribution of these species was very uneven and an established population of A. brasiliense in the Cerrado is reported for the first time. Other tick species (Amblyomma ovale, Amblyomma nodosum, Amblyomma parvum, Ixodes schulzei and Haemaphysalis leporispalustris) were found in lesser numbers. Domestic animals displayed tick infestations of both rural and urban origin as well as from natural areas (Rhipicephalus sanguineus sensu lato, Rhipicephalus microplus, Dermacentor nitens, A. sculptum, A. ovale, Amblyomma tigrinum, Argas miniatus). Amblyomma sculptum had the widest domestic host spectrum among all tick species. DNA of only one Rickettsia species, R. bellii, was found in an A. dubitatum tick. Several biological and ecological features of ticks of the studied areas are discussed.     

Parasitism (Trematoda,Digenea) in medusae from the southwestern Atlantic Ocean: medusa hosts,parasite prevalences,and ecological implications

Digenean are important endoparasites of fish with complex life cycles; some genera include medusae as secondary hosts. Their transmission to fish occurs when fish prey on these jelly hosts. Fish predation on jellyfish is a widespread phenomenon, even though predation by fish on jellyfish has not been determined through parasitism yet. We hypothesized that medusae with high prevalences of digeneans could be important for their transmission to fish. A total of 48,900 specimens of 50 medusa species were analyzed; 2,181 harbored digeneans. Opechona sp. and Monascus filiformis were the most frequent and abundant parasites with the widest range of hosts. Hemiuridae gen. sp. and Bacciger sp. were found in few specimens of some medusa species. Prevalences were unevenly distributed in the region. Three groups with high prevalence values were identified mainly related to frontal areas: Río de la Plata, Bahía Blanca, and North Patagonian tidal front. Eucheilota ventricularis, Clytia hemisphaerica, Proboscidactyla mutabilis, Liriope tetraphylla, and Aequoerea spp. were the medusae that contributed the most as secondary hosts to M. filiformis and Opechona sp. The high prevalences found in these medusae suggest that may be a fundamental part of the life cycles of both parasites in these areas.     

First assessment of the diet composition and trophic level of an assemblage of poorly known chondrichthyans off the central coast of Peru

Although chondrichthyans are conspicuously present in shallow waters, many ecological aspects of neritic species in the Humboldt Current System remain unknown. This study provides a first assessment of the diet of seven commercially exploited and understudied sympatric chondrichthyans inhabiting nearshore habitats off the central coast of Peru: four stingrays (Hypanus dipterurus, Myliobatis peruvianus, M. chilensis, and Urotrygon chilensis), a guitarfish (Pseudobatos planiceps), a smooth-hound shark (Mustelus mento), and a chimaera (Callorhinchus callorynchus). A total of 166 stomachs were examined between 2012 and 2015 and prey items were pooled for the total of years for analysis. Although our analysis did not account for inter seasons variability, our results suggest diet partitioning among species, except for the stingrays’ group. A diet based on soft-bottom polychaetes and fish was shared by H. dipterurus, M. peruvianus, and M. chilensis, while soft-bottom polychaetes and crabs were more important in U. chilensis. The smooth-hound shark and guitarfish exhibited a diet dominated by crabs, and the chimaera consumed mainly hard-bottom mollusks. Foraging habitat estimations distinguished two main habitats of association: Benthic, including the stingray U. chilensis, the chimaera, and the smooth-hound shark; and benthic-demersal, including the guitarfish, and the rest of stingrays. A pattern of feeding specialization was observed for H. dipterurus, P. planiceps, and C. callorynchus. Preliminary trophic level estimations based on diet composition placed these species as secondary consumers. Intraspecific dietary variation was assessed for P. planiceps and H. dipterurus as their sampled sizes allowed meaningful comparisons. The diet of P. planiceps varied from small to large sizes but not for H. dipterurus. No differences were detected on diet composition between males and females in either species. Despite the limited temporal resolution, this study provides the first insights of chondrichthyans predatory activity, suggesting diet partitioning among the species of this assemblage in a nearshore habitat of the central coast of Peru. Enhancing the temporal resolution of this type of studies would improve our knowledge on trophic functioning in the Humboldt Current ecosystem.     

A New record of four <Emphasis Type="Italic">Penicillium</Emphasis> species isolated from <Emphasis Type="Italic">Agarum clathratum</Emphasis> in Korea

Agarum clathratum, brown algae, play important ecological roles in marine ecosystem, but can cause secondary environment pollution when they pile up on the beach. In order to resolve the environment problem by A. clathratum, we focus to isolate and identify Penicillium because many species are well known to produce extracellular enzymes. A total of 32 Penicillium strains were isolated from A. clathratum samples that collected from 13 sites along the mid-east coast of Korea in summer. They were identified based on morphological characters and phylogenetic analysis using β-tubulin DNA sequences as well as a combined dataset of β-tubulin and calmodulin. A total of 32 strains were isolated and they were identified to 13 Penicillium species. The commonly isolated species were Penicillium citrinum, P. roseomaculatum, and Penicillium sp. Among 13 Penicillium species, four species – P. bilaiae, P. cremeogriseum, P. madriti, and P. roseomaculatum – have not been previously recorded in Korea. For these four new species records to Korea, we provide morphological characteristics of each strain.     

Dynamics of species composition of fish and some results of ichthyomonitoring in the middle course of the Oka (Ryazan oblast)

The dynamics of species composition of fish from the middle course of the Oka is considered. A total of 53 species of Cyclostomata and fish was previously recorded; however, only 43 species have been found at the present time. Due to different causes, ten species have disappeared, and ten new species have emerged. The species composition and structure of aboriginal fish population are characterized by relative stability; however, the total abundance of fish during the current decade, as compared to the 1970s, has considerably decreased. The sterlet Acipenser ruthenus, lake minnow Phoxinus precnurus, Volga zander Sander volgensis, and freshwater sculpin Cottus gobio belong to rare fish.     

Probiotic Potential of Autochthonous Bacteria Isolated from the Gastrointestinal Tract of Four Freshwater Teleosts

In this study, a total of 121 bacterial strains were isolated from the gastrointestinal tract of four teleostean species, namely striped snakehead (Channa striatus), striped dwarf catfish (Mystus vittatus), orangefin labeo (Labeo calbasu) and mrigal carp (Cirrhinus mrigala), among which 8 isolates showed promising antibacterial activity against four potential fish pathogens, Aeromonas hydrophila, Aeromonas salmonicida, Aeromonas sobria and Pseudomonas fluorescens and were non-hemolytic. The isolates were further screened in response to fish bile tolerance and extracellular digestive enzyme activity. Two bacterial strains MVF1 and MVH7 showed highest tolerance and extracellular enzymes activities, and selected for further studies. Antagonistic activity of these two isolates was further confirmed by in vitro growth inhibition assay against four selected fish pathogens in liquid medium. Finally, these two bacterial strains MVF1 and MVH7 were selected as potential probiotic candidates and thus identification by partial 16S rRNA gene sequence analysis. The bacterial isolates MVF1 and MVH7 were identified as two strains of Bacillus sp.     

Interspecific differences of respiratory functions of some freshwater fish species

Hemoglobin affinity to oxygen, Bohr effect, sodium, potassium, and magnesium ion concentrations of erythrocytes in the three fish species from Rybinsk Reservoir (golden carp Carassius auratus gibelio, bream Abramis brama and pike Esox lucius) immediately after catching and during acclimation to laboratory conditions were studied. Our own and literature data on some other fish species were analyzed. The relationship between the functional features of the hemoglobin and ionic environment was found, and the changes taking place during acclimation and interspecific differences of these indices were shown.     

Comparative analysis of otolith morphology in three species of <Emphasis Type="Italic">Scomber</Emphasis>

Geometric morphometrics is a quick and reliable approach to differentiate fish stocks based on the variation of otolith shapes. In this study, morphometric analysis of otolith shapes was used to differentiate three species of Scomber. The sagittae morphology of S. scombrus otolith is totally different from that of S. japonicus and S. australasicus. Multivariate analysis consistently showed that S. japonicus was morphologically similar to S. australasicus, whereas a significant difference in otolith shapes was detected between S. scombrus and other two species of Scomber. The rostrum, antirostrum, excisural notch and dorsal-posterior margin of the otolith reflect the main variations between the three species of Scomber. Shape indices and Fourier coefficients were used to discriminate fish species using analysis of variance and Fisher discriminant analysis. The shape indices successfully differentiated 100%, 95.7% and 96.4% of otoliths in S. japonicus, S. australasicus and S. scombrus, respectively, while the Fourier coefficients only discriminated 70.0%, 61.9% and 91.3% of the sagittae in S. japonicus, S. australasicus and S. scombrus. This study indicates that the shape analysis on the sagittae morphometrics of otoliths is a better method to differentiate species of Scomber.     

Genotypic characterization of Lactic acid bacteria in gut microbiome of freshwater fish

The present study focused on identification and genotypic characterization of Lactic acid bacteria (LAB) in the intestine of freshwater fish. 76 strains of LAB were isolated and identified by 16S rRNA gene sequences and hsp60 gene sequences as different strains of Lactobacillus plantarum, Lactobacillus pentosus, Lactobacillus fermentum, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus brevis, Lactobacillus reuteri, Lactobacillus salivarius, Pediococcus pentosaceus, Pediococcus acidilactici, Weissella paramesenteroides, Weissella cibaria, Enterococcus faecium, and Enterococcus durans. The hsp60 gene showed a higher level of sequence variation among the isolates examined, with lower interspecies sequence similarity providing more resolutions at the species level than the 16S rRNA gene. Phylogenetic tree derived from hsp60 gene sequences with higher bootstrap values at the nodal branches was more consistent as compared to phylogenetic tree constructed from 16S rRNA gene sequences. Closely related species L. plantarum and L. pentosus as well as species L. delbrueckii subsp. bulgaricus and L. fermentum were segregated in different cluster in hsp60 phylogenetic tree whereas such a distribution was not apparent in 16S rRNA phylogenetic tree. In silico restriction analysis revealed a high level of polymorphism within hsp60 gene sequences. Restriction pattern with enzymes AgsI and MseI in hsp60 gene sequences allowed differentiation of all the species including closely related species L. plantarum and L. pentosus, E. faecium and E. durans. In general, hsp60 gene with higher evolutionary divergence proved to be a better phylogenetic marker for the group LAB.     

Fish production in estuaries of Primorye

Production of fish communities in 15 different-types estuaries was assessed based on the data collected as a result of 90 surveys (860 seine stations) conducted in Primorye in 2002–2015. The main contribution to production was made by semi-anadromous species (the so-iuy mullet Liza haematocheilus, Far Eastern redfins Tribolodon spp., and Japanese smelt Hypomesus nipponensis, etc.). In both external (EP _ext) and internal (EP _int) polyhaline estuaries (EP) a substantial portion of the production was provided by resident marine species (mainly by the saffron cod Eleginus gracilis, Far Eastern smooth flounder Liopsetta pinnifasciata, and tidepool gunnel Pholis nebulosa) and southern immigrants (flathead grey mullet Mugil cephalus, dotted gizzard shad Konosirus punctatus, Japanese halfbeak Hyporhamphus sajori, and Pacific needlefish Strongylura anastomella). In mesohaline (EM) and oligohaline (EO) estuaries, the proportion of marine residents and southern immigrants was reduced to a minimum, while that of freshwater species (bighead gudgeon Gobio macrocephalus, Prussian carp Carassius gibelio, minnow Phoxinus spp., Amur bitterling Rhodeus sericeus, spiny bitterlings Acanthorhodeus spp., etc.) substantially added to the production of semi-anadromous fish. The mean fish biomass for the vegetation season varied in the 143–1463 mgC/m² range; the mean annual production was 174–4267 mgC/m² and the mean P/B ratio was 0.2–3.2. In 2007, the high annual production in the Artemovka River estuary, 9356 mgC/m², was formed by the juvenile so-iuy mullet of the strong yearclass that hatched in 2006. The lowest mean production and P/B values were typical mainly for the water bodies with a salinity more often close to that of the barrier zones (5–8‰ for α-horohalinicum and 22–26‰ for β-horohalinicum), i.e., for EM and EP _ext. This relationship is explained by the features of the osmotic regulation in fish of various origins and its ontogenetic variations. In particularly, the salinity in EM is more frequently close to the critical salinity (5–8‰, α-horohalinicum); thus, the proportion of juveniles of most of the species in the catches decreases (as their resistance to salinity variations is lower). This results in higher mean values of the specific and absolute production of fish communities in EP _int and EO as compared to those in EM. The conclusion was made that the estimates of fish production in the estuaries of Primorye are similar to those in the well-studied estuaries of the temperate, subtropical, and tropical zones. Moreover, they are comparable to the fish production estimates for mesotrophic and eutrophic lakes in northwestern Russia, substantially lower than those for large lowland rivers, and higher than those for small rivers. The fish production in seas, including the Japan/East Sea (0.20 gC/m²) and, particularly, Peter the Great Bay (0.28 gC/m²), is mostly lower than that in Primorye estuaries.     

Findings of new and rare fish species in the coastal zone of the Crimea (the Black Sea)

Characteristics of seven Atlantic-Mediterranean fish species are provided. Of them, four (gobies—yellow-headed Gobius xanthocephalus and red-mouthed G. cruentatus, incognito blenny Parablennius incognitus, and greater pipefish Syngnathus acus) were either first found in the Black Sea coastal zone of the Crimea, or their findings were doubted, and three species (thin-lipped grey mullet Liza ramada, European barracuda Sphyraena sphyraena, and Black Sea salmon Salmo trutta labrax) are very rare. Over the last decade, the authors recorded 15 fish species; of them, seven Atlantic-Mediterranean species have dispersed along the Crimean coasts by now, one endemic of the far eastern seas (chameleon goby Tridentiger trigonocephalus) has naturalized in Sevastopol Bay, four invading species, freshwater by origin, permanently occur in the estuary zones of the peninsula; the remaining three species are known from single findings and apparently belong to the category of accidental fish. An increase in the species composition of ichthyofauna off the Black Sea coasts of the Crimea results from the on-going process of mediterranization—the invasion in the estuary of freshwater tolerant species at the expense of accidental species that penetrated here either independently or with ballast waters.     

Abundance,distribution, and territory areas of rock-dwelling Lake Tanganyika cichlid fish species

Lake Tanganyika, the second-oldest and second-deepest lake in the world, harbors an impressive cichlid fish fauna counting about 250 endemic species that are characterized by a great level of ecological, morphological, and behavioral specialization. This study describes and compares cichlid fish communities at two rocky shores with differential human impact in the south of Lake Tanganyika. Species inventories and depth-dependent abundances were elaborated. About 41 and 46 sympatric cichlid species were recorded in the two study sites, respectively. Variabilichromis moorii was the most abundant species (29–60% of total number of fishes), followed by Aulonocranus dewindti (3–19%), Tropheus moorii (12%), Ophthalmotilapia ventralis (4–10%), Eretmodus cyanostictus (6–11%), and Cyathopharynx furcifer (0.01–9%). All other species had abundances below 5%. It further emerged that large cichlids such as Petrochromis species, Cyathopharynx furcifer, and Lobochilotes labiatus were very rare at one location, with frequencies of 0.55% or less. Territorial sizes of three particularly abundant species, Variabilichromis moorii, Aulonocranus dewindti, and Tropheus moorii, were assessed by behavioral observations. We distinguished between territorial core areas and total defended area, yielding average core areas between 0.4 (V. moorii) and 1.6 m² (T. moorii), and total defended areas averaging for each species between 1.6 (V. moorii) and 5.0 m² (A. dewindti) with no significant differences between the two study sites. The data on individual densities are also relevant for evolutionary studies, in that they allow more accurate calculations of effective population sizes.     

Observations on the specific associations found between scyphomedusae and commensal fish and invertebrates in the Philippines

Our observations on scyphomedusae from selected Philippine embayments identified specific animals commensal with five species of rhizostome scyphomedusae, Acromitoides purpurus, Mastigias sp., Phyllorhiza punctata, Rhopilema hispidum and Versuriga anadyomene. Acromitoides purpurus medusae harbor the crab Charybdis feriata, the carangid fish Alepes djedaba and the poecilostomatoid copepod Paramacrochiron sp. The carangid A. djedaba was an associate of the blue morph of A. purpurus and Rhopilema hispidum in Panguil Bay. A black-pigmented Alepes sp. was found associated with burgundy A. purpurus medusae in Carigara Bay. Charybdis feriata juveniles are common commensals of all morphs of A. purpurus, R. hispidum and P. punctata medusae. Only the zooxanthelate Mastigias sp. lacked animal symbionts. We invoke the “meeting-point hypothesis” and the general theory of fish aggregation to floating structures to explain fish symbiosis with their medusan hosts. The invertebrate-medusa associations are attributed to feeding behaviors and predator avoidance by resident commensals. This study provides record of the poorly studied scyphozoan species and their association with animals in Philippine waters. Finally, we discuss the potential reasons why the golden spotted jellyfish, Mastigias sp., appears to lack animal commensals.