Gross colour pattern is used to distinguish between opponents during aggressive encounters in a Lake Malawi cichlid

Abstract – The role of male colouration in the behavioural interactions of haplochromine cichlids has received much attention. Previous studies supported the role played by visual signals during interactions of rock‐dwelling cichlids, or mbuna, from Lake Malawi. It has largely been assumed that hue, and not pattern, is the primary signal encoded in male colouration; thus, the role of colour pattern has received less attention. We explored the use of visual signals during aggression in Labeotropheus fuelleborni by using identically and differently coloured opponents and by offering these opponents under coloured illumination. We presented two simultaneous opponents to males and found that the focal male’s responses depended upon opponent colour pattern; similarly patterned opponents received more aggression, even if presented under a hue‐obscuring light source. These results support findings that gross colour pattern may be more important than hue in interactions among the mbuna and further support an important role for visual communication in these fishes.     

Habitat diversity relative to wave action on rocky shores: implications for the selection of marine protected areas

• 1. Current selection of marine protected areas in South Africa is based on objective criteria including biogeographic representation and habitat heterogeneity. This paper specifically examines rocky shores on the west coast of South Africa to determine whether they are divisible into discrete ‘habitats’ that need independent conservation.
• 2. Seventeen rocky shores spanning the full spectrum of wave exposure were compared in terms of maximum wave forces, biomass, species richness and diversity among zones and sites. Three biotic assemblages were identified, characterizing sheltered, semi‐exposed to exposed, and very exposed habitats. Differences among these were clear‐cut low on the shore but disappeared at the top of the shore where wave action was attenuated and desiccation uniformly intense.
• 3. The recognition of three discrete biologically‐defined habitats means that rocky shores cannot be regarded as a uniform habitat for conservation purposes. All three components need protection if the full spectrum of rocky‐shore communities is to be conserved.
• 4. It is argued that this approach allows habitats to be defined in an objective manner, and that once this has been done, habitat heterogeneity constitutes a better measure of conservation value of an area than a ‘hotspot’ approach based on species richness and endemism.

Copyright © 2008 John Wiley & Sons, Ltd.     

Islands in the ice stream: were spawning habitats for native salmonids in the Great Lakes created by paleo‐ice streams?

Lake trout Salvelinus namaycush, lake whitefish Coregonus clupeaformis and cisco Coregonus artedi are salmonid fishes native to the Laurentian Great Lakes that spawn on rocky substrates in the fall and early winter. After comparing the locations of spawning habitat for these species in the main basin of Lake Huron with surficial substrates and the hypothesized locations of fast‐flowing Late Wisconsinan paleo‐ice streams, we hypothesize that much of the spawning habitat for these species in Lake Huron is the result of deposition and erosion by paleo‐ice streams. This hypothesis may represent a new framework for the identification and protection of spawning habitat for these native species, some of which are currently rare or extirpated in some of the Great Lakes. We further suggest that paleo‐ice streams may have been responsible for the creation of native salmonid spawning habitat elsewhere in the Great Lakes and in other glaciated landscapes.     

A rapid biodiversity assessment methodology tested on intertidal rocky shores

• 1. Conservation managers require biodiversity assessment tools to estimate the impact of human activities on biodiversity and to prioritize resources for habitat protection or restoration. Large‐scale programs have been developed for freshwater ecosystems which grade sites by comparing measured versus expected species richness. These models have been applied successfully to habitats that suffer from systemic pressures, such as poor water quality. However, pressures in other habitats, such as rocky intertidal shores, are known to induce more subtle changes in community composition.
• 2. This paper tests a biodiversity assessment methodology that uses the ANOSIM R statistic to quantify the biological dissimilarity between a site being assessed and a series of reference sites selected on the basis of their similar environmental profile. Sites with high R values for assemblage composition have an anomalous assemblage for their environmental profile and are potentially disturbed.
• 3. This methodology successfully identified moderate to heavily perturbed sites in a pilot study on 65 rocky intertidal sites in south‐eastern Australia. In general, measures based on percentage cover (flora and sessile invertebrates) were more sensitive than abundance (fauna). Copyright © 2010 John Wiley & Sons, Ltd.

     

Some effects of marine reserve protection on the population structure of two spearfishing target‐fish species,Dicentrarchus labrax (Moronidae) and Sparus aurata (Sparidae), in shallow inshore waters,along a rocky coast in the northwestern Mediterranean Sea

1. The relative abundances of two highly sought after spearfishing target‐fish species, Dicentrarchus labrax (Linnaeus 1758) and Sparus aurata Linnaeus 1758, were compared using underwater visual censuses in shallow (<5 m) inshore waters along rocky shores inside and outside a marine reserve area in the northwestern Mediterranean Sea (Banyuls‐sur‐Mer region, France). 2. The relative abundances of these two species were consistently lower outside the reserve area, which comprised around 40% of the 25.6 km of inshore coastal waters surveyed. 3. The demographic structure of D. labrax was also different inside and outside the protected area, the proportion of larger fish being significantly higher in the marine reserve. 4. The direct and indirect impacts of spearfishing are postulated to explain the distributional and population structural characteristics of these two species in the shallow waters off this rocky coast. 5. Prohibition of spearfishing has favoured the persistence of these species during summer (the main spearfishing season) in the shallower inshore waters inside the area of the Cerbère/Banyuls‐sur‐Mer marine reserve. 6. These preliminary results indicate the need for additional work in this area and further surveys to ascertain spearfishing impacts on target‐fish species in the vicinity of other marine protected areas. Copyright © 2001 John Wiley & Sons, Ltd.     

Nursery habitat for Asian horseshoe crabs along the northern Beibu Gulf,China: Implications for conservation management under baseline gaps

1. Identification, protection and enhancement of essential habitats are priority issues for management and restoration of exploited species. The shores utilized by Asian horseshoe crabs as nurseries were surveyed and the coastal habitat characteristics were described in the northern Beibu Gulf of China. Regression models were applied to explore species‐habitat relationships.
2. Fourteen and ten nursery sites were identified for Tachypleus tridentatus and Carcinoscorpius rotundicauda populations, respectively. Xiacun and Jinhaiwan in the eastern region of the northern Beibu Gulf were the essential nurseries for T. tridentatus, whereas Shanxin and Jiaodong in the western part were the primary nursery shores for C. rotundicauda. These shores supported high densities (4–6 individuals/100 m²) of juvenile horseshoe crab populations.
3. Mangrove and seagrass coverage area, coupled with sediment physico‐chemical parameters, particularly grain size, and the environmental heterogeneity of nursery habitats explained the distribution pattern of juvenile populations. Most juvenile populations were found along the outer fringe of mangroves in the small shallow estuary, particularly near outflows of tidal creeks with generally higher chlorophyll a and organic carbon contents. The distribution of high‐density juvenile populations of both species also overlapped with areas of seagrass patches.
4. These findings highlight the importance of mangroves and seagrasses in the nursery habitat use of Asian horseshoe crabs. Preserving the estuarine habitats with these vegetation types and identifying the high‐use nursery sites should be prioritised in China and other Asian places to conserve the declining Asian horseshoe crab populations.

     

Microhabitat preferences of fish assemblages in the Udzungwa Mountains (Eastern Africa)

Environmental flow assessment (EFA) involving microhabitat preference models is a common approach to set ecologically friendly flow regimes in territories with ongoing or planned projects to develop river basins, such as many rivers of Eastern Africa. However, habitat requirements of many African fish species are poorly studied, which may impair EFAs. This study investigated habitat preferences of fish assemblages, based on species presence–absence data from 300 microhabitats collected in two tributaries of the Kilombero River (Tanzania), aiming to disentangle differences in habitat preferences of African species at two levels: assemblage (i.e. between tributaries) and species (i.e. species‐specific habitat preferences). Overall, flow velocity, which implies coarser substrates and shallower microhabitats, emerged as the most important driver responsible of the changes in stream‐dwelling assemblages at the microhabitat scale. At the assemblage level, we identified two important groups of species according to habitat preferences: (a) cover‐orientated and limnophilic species, including Barbus spp., Mormyridae and Chiloglanis deckenii, and (b) rheophilic species, including Labeo cylindricus, Amphilius uranoscopus and Parakneria spekii. Rheophilic species preferred boulders, fast flow velocity and deeper microhabitats. At the species level, we identified species‐specific habitat preferences. For instance, Barbus spp. preferred low flow velocity shallow depth and fine‐to‐medium substratum, whereas L. cylindricus and P. spekii mainly selected shallow microhabitats with coarse substrata. Knowledge of habitat preferences of these assemblages and species should enhance the implementation of ongoing and future EFA studies of the region.     

Habitat selection and sampling design for ecological assessment of heterogeneous ponds using macroinvertebrates

• 1. Habitat heterogeneity has many implications in ecological assessment studies. On one hand it provides varying niches for organisms, increasing diversity. On the other hand, the inherent spatial variability of structurally complex systems may overlap with ecological condition making it difficult to disentangle the effects of perturbation. This study investigated the combined and single effects of habitat and pond condition on the macroinvertebrate assemblages of 35 ponds located in north‐west Spain and spanning a range of water quality and habitat characteristics.
• 2. Macroinvertebrate communities and several environmental variables were sampled in the summer of 2004 or 2003. Samples were collected from four dominant habitats (vegetated shores, shores without vegetation, submerged vegetation, bare sediments) following a time‐limited sampling. Non‐metric multidimensional scaling and two‐way crossed ANOSIM were used to investigate the taxonomic and functional differences in macroinvertebrate assemblage structure among habitats (four types) and pond conditions (optimal, good, moderate, poor, very poor). To investigate the individual and combined effects of pond condition and habitat on several diversity measures GLM models were used. In addition, the accuracy of two sampling designs — stratified and multihabitat — was compared using the CVs of seven macroinvertebrate attributes.
• 3. Results showed that macroinvertebrate communities differed significantly, albeit weakly, among habitat types and pond condition categories. In particular, the abundance of several Chironomidae genera, rarefied richness and Shannon index decreased both in perturbed systems and bare sediments, whereas no marked differences occurred between shores and submerged vegetation.
• 4. We suggest that a multihabitat approach together with the use of community attributes not (or slightly) affected by habitat type will provide more comparable results across ponds than a stratified approach or observation of the whole community, especially in ponds where degradation leads to habitat loss.Copyright © 2009 John Wiley & Sons, Ltd.

     

Reliance on lakes by salmon,trout and charr (Oncorhynchus,Salmo and Salvelinus): An evaluation of spawning habitats,rearing strategies and trophic polymorphisms

Salmonid fishes may reside within or migrate between stream and lake habitats, or undergo anadromous migrations between freshwater and the ocean. While the degree of anadromy of salmonids has been thoroughly compared, no analogous review has examined the degree of lake use. To assess the extent of reliance on lake habitat in this family, we considered 16 species of salmon, trout and charr from the genera Oncorhynchus, Salmo and Salvelinus, comparing their (a) use of lakes as spawning habitat, (b) rearing strategies in lakes, and (c) occurrence and diversity of lacustrine trophic polymorphism. In identifying the primary life‐history patterns of each species and exploring the lesser‐known lacustrine behaviours, we found that the extent of reliance on lakes exhibits a negative association with the degree of anadromy. Oncorhynchus rely least on lakes, Salmo to an intermediate level and Salvelinus the most, opposite of the general prevalence of anadromy among these genera. Lakes are critical to adfluvial and lake‐resident salmonids, but they also support anadromous and fluvial life histories by providing spawning, rearing, overwintering and/or summer refuge habitat. Adfluviality, although a non‐anadromous life history, consists of similar migration‐related traits and behaviours as anadromy, including the parr–smolt transformation, sex‐biased patterns of migration and residency, and the presence of precocious males. Lakes support life‐history variants, reproductive ecotypes and trophic morphs unique to lacustrine habitat. Therefore, conservation of salmonids is dependent on maintaining the diversity and quality of their habitats, including lakes.     

青岛太平角岩相潮间带大型海藻群落初步调查

对青岛太平角(36°02′N,120°21′E)岩相潮间带大型海藻群落进行了为期1年(2010年5月-2011年4月)逐月的定性调查研究。结果表明:1.采集到大型海藻3门36种,其中红藻门16属19种,占52.8%;褐藻门7属10种,占27.8%;绿藻门5属7种,占19.4%。2.青岛太平角潮间带大型海藻群落的种类组成中红藻种类最多,褐藻其次,绿藻最少。3.青岛太平角潮间带群落中大型海藻的种类组成和藻总量(株)有明显的季节变化:春季海藻的种类和数量都非常大,秋冬季节其次,夏季海藻种类和数量最少。4.孔石莼、鼠尾藻和珊瑚藻为青岛太平角岩相潮间带大型海藻群落的最常见种。5.青岛夏季绿潮藻种浒苔是由其他海域漂流而来,且较其他藻种更适应夏季较高水温,使其短时间内迅速生长。     

Water levels in a highland lake control the quantity and quality of spawning habitat for a littoral‐spawning galaxiid fish

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Mass selection for red colour in Oreochromis niloticus (Linnaeus 1758)

Mass selection in Oreochromis niloticus, Stirling strain, was used to obtain a red colour homozygous dominant population from a base population containing wild type and red fish with black blotches. Each selection generation included 28–80 breeders in a 1:1 male:female ratio and a density of 1 pair m^?2.First selection for red colour was done when fry reached 3 g, discarding those exhibiting wild type colouring or with a high black blotch incidence. Second selection was done before fish began the reproduction stage. To determine if red‐coloured fish were homozygous, a progeny test was done with the fifth selection generation using eight individual crosses of red males with wild type females and wild type males with red females. Red colour proportion increased from 5.6% in the first generation to 100% in the fifth generation. All fry in the progeny test were red colour, inferring that the population was homozygous dominant (RR). Accumulated inbreeding rate in the fifth selection generation was 1.79%. The selection process did not affect fecundity as fry production in red colour females was similar to that in wild type females. Mass selection to obtain a red homozygous population in O. niloticus, Stirling strain, was appropriate and was also effective in reducing black blotch incidence in the same species.     

Community patterns generated by human harvesting on Chilean shores: a review

1. The Chilean rocky coast has been exploited for food by coastal gatherers for at least 8500 years BP and probably was an important factor in how prehistoric people were able to colonize the South Americas Pacific Rim. The main species targeted in the past were the same as those today except that now the gatherers are resident and the fishing activity is more intense and persistent. 2. With many pertinent studies from around the world having been published on this topic, mostly conducted in Marine Reserves, this review tries to identify the main patterns that can help us recognize, in the Chilean intertidal, the degree of exploitation on wave exposed and wave protected rocky shore habitats. 3. Three clear patterns were identified depending on the trophic level adopted by the human gatherers in the food chain of the intertidal zone. First, when the humans act as herbivores, collecting the large laminarian Durvillaea antarctica, adult plants disappear from the accessible sites, especially the midlittoral, semi‐exposed and exposed habitats. 4. Second, when humans harvest the ecologically important herbivorous archeogastropoda Fissurella spp., this results in the red alga Mazzaella laminarioides covering almost 100% of the midlittoral rocks. Third, when humans become top predators by collecting the muricid carnivore Concholepas concholepas, then bivalves, mainly Perumytilus purpuratus, cover the rocks in multiple layers. 5. These patterns contribute to the evaluation of the state of conservation of the Chilean rocky intertidal shores, especially because the north and the south are beginning to be connected by a new coastal road. Thus it is necessary to evaluate urgently, on a large spatial scale, the state of conservation of these communities, in order to help select the appropriate places for establishing Marine Reserves. Copyright © 2001 John Wiley & Sons, Ltd.     

Low genetic variation and isolation of northern peripheral populations of a red seaweed (Grateloupia lanceola)

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High‐resolution modelling of ocean circulation can reveal retention spots important for biodiversity conservation

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Atlantic salmon Salmo salar L., brown trout Salmo trutta L. and Arctic charr Salvelinus alpinus (L.): a review of aspects of their life histories

Abstract – Among the species in the family Salmonidae, those represented by the genera Salmo, Salvelinus, and Oncorhynchus (subfamily Salmoninae) are the most studied. Here, various aspects of phenotypic and life‐history variation of Atlantic salmon Salmo salar L., brown trout Salmo trutta L., and Arctic charr Salvelinus alpinus (L.) are reviewed. While many strategies and tactics are commonly used by these species, there are also differences in their ecology and population dynamics that result in a variety of interesting and diverse topics that are challenging for future research. Atlantic salmon display considerable phenotypic plasticity and variability in life‐history characters ranging from fully freshwater resident forms, where females can mature at approximately 10 cm in length, to anadromous populations characterised by 3–5 sea‐winter (5SW) salmon. Even within simple 1SW populations, 20 or more spawning life‐history types can be identified. Juveniles in freshwater can use both fluvial and lacustrine habitats for rearing, and while most smolts migrate to sea during the spring, fall migrations occur in some populations. At sea, some salmon undertake extensive oceanic migrations while other populations stay within the geographical confines of areas such as the Baltic Sea. At the other extreme are those that reside in estuaries and return to freshwater to spawn after spending only a few months at sea. The review of information on the diversity of life‐history forms is related to conservation aspects associated with Atlantic salmon populations and current trends in abundance and survival. Brown trout is indigenous to Europe, North Africa and western Asia, but was introduced into at least 24 countries outside Europe and now has a world‐wide distribution. It exploits both fresh and salt waters for feeding and spawning (brackish), and populations are often partially migratory. One part of the population leaves and feeds elsewhere, while another part stays as residents. In large, complex systems, the species is polymorphic with different size morphs in the various parts of the habitat. Brown trout feed close to the surface and near shore, but large individuals may move far offshore. The species exhibits ontogenetic niche shifts partly related to size and partly to developmental rate. They switch when the amount of surplus energy available for growth becomes small with fast growers being younger and smaller fish than slow growers. Brown trout is an opportunistic carnivore, but individuals specialise at least temporarily on particular food items; insect larvae are important for the young in streams, while littoral epibenthos in lakes and fish are most important for large trout. The sexes differ in resource use and size. Females are more inclined than males to become migratory and feed in pelagic waters. Males exploit running water, near‐shore and surface waters more than females. Therefore, females feed more on zooplankton and exhibit a more uniform phenotype than males. The Arctic charr is the northernmost freshwater fish on earth, with a circumpolar distribution in the Holarctic that matches the last glaciation. Recent mtDNA studies indicate that there are five phylogeographic lineages (Atlantic, Arctic, Bering, Siberian and Acadian) that may be of Pleistocene origin. Phenotypic expression and ecology are more variable in charr than in most fish. Weights at maturation range from 3 g to 12 kg. Population differences in morphology and coloration are large and can have some genetic basis. Charr live in streams, at sea and in all habitats of oligotrophic lakes, including very deep areas. Ontogenetic habitat shifts between lacustrine habitats are common. The charr feed on all major prey types of streams, lakes and near‐shore marine habitats, but has high niche flexibility in competition. Cannibalism is expressed in several cases, and can be important for developing and maintaining bimodal size distributions. Anadromy is found in the northern part of its range and involves about 40, but sometimes more days in the sea. All charr overwinter in freshwater. Partial migration is common, but the degree of anadromy varies greatly among populations. The food at sea includes zooplankton and pelagic fish, but also epibenthos. Polymorphism and sympatric morphs are much studied. As a prominent fish of glaciated lakes, charr is an important species for studying ecological speciation by the combination of field studies and experiments, particularly in the fields of morphometric heterochrony and comparative behaviour.     

Identification of sex‐specific markers and heterogametic XX/XY sex determination system by 2b‐RAD sequencing in redtail catfish (Mystus wyckioides)

Sex‐specific markers provide significant molecular basis for sex control breeding biotechnology to produce all‐male or all‐female fish in commercial breeding. Redtail catfish (Mystus wyckioides), one of the commercial bagrid catfishes distributed in Southeast Asian, which have a long sexual maturation period that can last 3–5 years and males have apparent growth advantage over females, but its sex determination system remains unknown. In this study, we first applied 2b‐RAD‐seq approach to identify three male‐specific 2b‐RAD‐tags and one male heterogametic SNP locus and validated by blast to the genome survey sequences and PCR amplification in both wild and breeding populations. To get longer sex‐specific region, we performed genome walking and obtained a 4,630 bp of Y‐specific sequence and 4,581 bp of X‐specific sequence from the 2b‐RAD‐tag ref189950 with 92.19% nucleotide identity between them. And 9,923 bp/3,935 bp of Y‐specific sequences and 8,491 bp/5,172 bp of X‐specific sequences were also identified with 77.49% and 57.07% nucleotide identity in ref208528 and ref210837, respectively. Subsequently, three different kinds of sex‐specific primers with different length products were designed based on the detected highly sex differentiated regions and could be used to distinguish males and females both in wild and artificially bred populations. What is more, the X‐specific fragment was discovered to produce the dosage effect association in females and in males. The data suggest that male heterogametic XX/XY sex determination system should exist in the redtail catfish. More significantly, the sex‐specific markers are of great value to protect wild resources and improve the efficiency of all‐male breeding practices for aquaculture in the redtail catfish.     

Adapting a multi‐species tool for single‐species impact assessments: Managing fishes at risk in Canada

1. To assess the impacts of human activity on fishes and fish habitat, impact assessment tools use single‐ and multi‐species approaches depending on the ecological and socio‐economic objectives. In Canadian aquatic ecosystems, single‐ and multi‐species impact assessments are guided by the Species at Risk Act and Fisheries Act, respectively. Yet, for species protected under the Species at Risk Act, the sparse data often require alternative approaches to risk assessment.
2. The goal of this study was to evaluate whether a database‐derived multi‐species tool – the Habitat Ecosystem Assessment Tool (HEAT) – can be used for single‐species impact assessments. Using an empirical example of proposed drain maintenance in a tributary of Lake St. Clair, the net loss of suitable habitat was evaluated across six conservation targets, ranging from single species, such as the pugnose shiner (Notropis anogenus) and the yellow perch (Perca flavescens), to the entire fish assemblage. Model outcomes were compared across various habitat suitability indices, spatial resolutions, and environmental habitat layers.
3. The net loss of suitable habitat varied widely across conservation targets and was greatest for the rare specialist species (pugnose shiner). Single‐species conservation targets were more sensitive to variation in spatial resolution and uncertainty in model input parameters. The results of this study emphasize that single‐ and multi‐species conservation targets should not be considered equal, especially when species differ in abundance and niche breadth.
4. This study demonstrates the flexibility of HEAT for evaluating potential impacts of human disturbance on fishes and their habitat. Future development of this tool should expand beyond physical habitat, to include other factors relevant to species distribution and survival (e.g. biotic interactions).

     

Interspecific competition between the round goby,Neogobius melanostomus,and the logperch,Percina caprodes,in the Duluth‐Superior Harbour

The Laurentian Great Lakes have been the site of numerous aquatic invasive species such as the sea lamprey, zebra mussel and round goby. To further understand interactions between invasive and native species in situ, competitive interactions between native logperch (Percina caprodes) and invasive round goby (Neogobius melanostomus) were examined using submerged enclosures in the Duluth‐Superior Harbour. Experiments were conducted on rocky or sandy substrate throughout the spring and summer months. Trials consisted of single fish, paired conspecifics or round goby/logperch pairs with weight change determined after 28 days. The round gobies were able to outcompete and/or negatively affect logperch on rocky substrates as a direct result of round goby/logperch interactions, as logperch fared well when round gobies were excluded from the enclosures. Although there is evidence that round gobies exclude logperch from rocky substrates, the logperch population remains close to pre‐invasion levels in the predominantly soft‐bottomed harbour. The continued coexistence of the logperch with the round goby is attributed to the vastly greater area of soft‐bottom vs. rocky substrate in the harbour, with the round gobies in the soft bottom younger and smaller than those in the rocky substrate. Recent evidence suggests that the round goby population is declining on the soft substrates indicating that the two populations will continue to coexist in the harbour.