Is it possible to photoperiod manipulate spawning time in planktivorous fish ? A long-term experiment on Atlantic herring

The oocyte development (vitellogenesis) of individual fish is highly dependent upon their physiology which is influenced by both intrinsic and extrinsic factors. Thus, if individuals encounter poor biophysical conditions, they will likely be unable to reproduce. The photoperiod is an external factor that is constant between years but with increasing intra-annual (seasonal) variation polewards. In high-latitude marine environments, several ecological processes are strongly photic entrained, e.g., the planktonic spring bloom. However, it is still unclear whether day length or planktonic peaks (feeding opportunity) is the main timer or regulator behind gametogenesis not only for teleost piscivores but also for planktivores living in these waters. Hence, we experimentally investigated the role of photoperiod steering vitellogenesis in the planktivorous Atlantic herring (Clupea harengus), rearing larvae up to the mature adult stage. We imposed a natural and 6-month offset photoperiod hypothesising that vitellogenesis is entrained by this photic zeitgeber. The results of our experiment clearly demonstrated that herring have a strong photic zeitgeber acting upon vitellogenesis according to the experienced photoperiod. Thus, the Offset Group showed a displacement in vitellogenesis of 6 months. The second hypothesis that feeding opportunities play a clear role in assisting this photic zeitgeber in Atlantic herring could be rejected. This clarification supports that the survival potential of the larvae is the main selection pressure in operation in these respects, i.e., rather than the extent of feeding opportunities of the adults.publishedVersio

Using ecological evidence to refine approaches to deploying offshore artificial reefs for recreational fisheries

Artificial reefs have many applications but are best known for their deployments to enhance recreational fisheries by creating new habitat in areas where natural reef is otherwise limited. The expectation is that fish assemblages will take up residence on artificial reefs and that these assemblages will become at least similar, if not more diverse and abundant, to those on natural reefs. Although designed, purpose-built artificial reefs are becoming more widely used in support of recreational fisheries and many of the historic issues have been resolved, conservation practitioners and managers still face challenges as to the type, number, and arrangement of structures and where to deploy them to maximize benefits and minimize risks. The ecological literature was reviewed to develop and enhance contemporary principles of artificial reef best practices for utilization. Our review identified optimal shapes, vertical relief, void spaces, and unit arrangements for increasing volumes and diversity of catch to recreational fishers and we provide a tool for identifying the least constrained areas for artificial reef deployment. We suggest; (a) monitoring of noncatch motivators in combination with quantitative indicators of the fishing activity (e.g., catch rate and effort) will provide the best understanding of success or failure of an artificial reef deployment; (b) choosing target species for informing purpose-built artificial reef designs to be reef-associated, demersal, philopatric, territorial, and obligatory reef species that are desired by local recreational fishers; and (c) considering the ecosystem services provided by artificial reefs beyond those associated with recreational fishing

Increasing habitat complexity on seawalls: Investigating large- and small-scale effects on fish assemblages.

The construction of artificial structures in the marine environment is increasing globally. Eco-engineering aims to mitigate the negative ecological impacts of built infrastructure through designing structures to be multifunctional, benefiting both humans and nature. To date, the focus of eco-engineering has largely been on benefits for benthic invertebrates and algae. Here, the potential effect of eco-engineered habitats designed for benthic species on fish was investigated. Eco-engineered habitats ("flowerpots") were added to an intertidal seawall in Sydney Harbour, Australia. Responses of fish assemblages to the added habitats were quantified at two spatial scales; large (among seawalls) and small (within a seawall). Data were collected during high tide using cameras attached to the seawall to observe pelagic and benthic fish. At the larger spatial scale, herbivores, planktivores, and invertebrate predators were generally more abundant at the seawall with the added flowerpots, although results were temporally variable. At the smaller spatial scale, certain benthic species were more abundant around flowerpots than at the adjacent control areas of seawall, although there was no general pattern of differences in species density and trophic group abundance of pelagic fish between areas of the seawall with or without added habitats. Although we did not find consistent, statistically significant findings throughout our study, the field of research to improve fish habitat within human-use constraints is promising and important, although it is in its early stages (it is experimental and requires a lot of trial and error). To advance this field, it is important to document when effects were detected, and when they were not, so that others can refine the designs or scale of habitat enhancements or their study approaches (e.g., sampling protocols)

Historical and contemporary determinants of global phylogenetic structure in tropical reef fish faunas

Identifying the main determinants of tropical marine biodiversity is essential for devising appropriate conservation measures mitigating the ongoing degradation of coral reef habitats. Based on a gridded distribution database and phylogenetic information, we compared the phylogenetic structure of assemblages for three tropical reef fish families (Labridae: wrasses, Pomacentridae: damselfishes and Chaetodontidae: butterflyfishes) using the net relatedness (NRI) and nearest taxon (NTI) indices. We then related these indices to contemporary and historical environmental conditions of coral reefs using spatial regression analyses. Higher levels of phylogenetic clustering were found for fish assemblages in the Indo-Australian Archipelago (IAA), and more particularly when considering the NTI index. The phylogenetic structure of the Pomacentridae, and to a lower extent of the Chaeotodontidae and Labridae, was primarily associated with the location of refugia during the Quaternary period. Phylogenetic clustering in the IAA may partly result from vicariance events associated with coral reef fragmentation during the glacial periods of the Quaternary. Variation in the patterns among fish families further suggest that dispersal abilities may have interacted with past habitat availability in shaping the phylogenetic structure of tropical reef fish assemblages

Coastal greening of grey infrastructure: an update on the state-of-the-art

\ua9 2023 Emerald Publishing Limited: All rights reserved.In the marine environment, greening of grey infrastructure (GGI) is a rapidly growing field that attempts to encourage native marine life to colonize marine artificial structures to enhance biodiversity, thereby promoting ecosystem functioning and hence service provision. By designing multifunctional sea defences, breakwaters, port complexes and off-shore renewable energy installations, these structures can yield myriad environmental benefits, in particular, addressing UN SDG 14: Life below water. Whilst GGI has shown great promise and there is a growing evidence base, there remain many criticisms and knowledge gaps, and some feel that there is scope for GGI to be abused by developers to facilitate harmful development. Given the surge of research in this field in recent years, it is timely to review the literature to provide an update update on the state-of-the-art of the field in relation to the many criticisms and identify remaining knowledge gaps. Despite the rapid and significant advances made in this field, there is currently a lack of science and practice outside of academic sectors in the developed world, and there is a collective need for schemes that encourage intersectoral and transsectoral research, knowledge exchange, and capacity building to optimize GGI in the pursuit of contributing to sustainable development

Клинико-биохимические аспекты развития обструкции бронхов при бронхиальной астме

The aim of this study was to investigate NO- and lipid peroxidation (LPO)-related airway reactivity and its correlation to ventilation disorders in different clinical variants of asthma. NO, malone dialdehyde, IL-4, TNF-α, and IgE were measured in BAL fluid and blood serum of 39 asthma patients and 15 healthy volunteers matched for age and gender.In patients with stable asthma, airflow parameters in small and medium airways were significantly decreased compared to those of healthy persons. Concentrations of key cytokines of atopic inflammation in BAL fluid and serum were increased in asthma patients. Serum IgE tended to decrease and IL-4 and TNF-α in BAL fluid increased in asthma patients while the disease worsened. Inverse correlations were found between NO and TNF-α, malone dialdehyde concentration and parameters of bronchial obstruction.In conclusion, NO production in airways is caused by strong accumulation of inflammatory cells with high metabolic activity resulting in release of inflammatory and pro-inflammatory cytokines which regulate immunopathological reagine-induced inflammation.Цель исследования состояла в оценке активности оксида азота (NO) и процессов перекисного окисления липидов (ПОЛ) в дыхательных путях при различных клинических формах БА и взаимосвязи этих процессов с нарушениями функции внешнего дыхания (ФВД). Проведена оценка содержания NO, малонового диальдегида (МДА), интерлейкина-4 (IL-4), фактора некроза опухоли α (TNF-α) и иммуноглобулина Е (IgE) в жидкости бронхоальвеолярного лаважа (ЖЖБАЛ) и сыворотке крови 39 пациентов с БА и у 15 добровольцев, сопоставимых по возрасту и полу. У всех обследованных больных БА в период клинической ремиссии, в отличие от здоровых лиц, достоверно снижены показатели, характеризующие проходимость мелких и средних бронхов. Подтверждено повышение содержания ключевых цитокинов атопического воспаления в ЖБАЛ и в сыворотке крови больных БА. Выявлены тенденции к снижению содержания IgE в сыворотке крови и повышению IL-4 и TNF-α в жидкости бронхоальвеолярного лаважа у больных БА по мере нарастания тяжести заболевания. Обнаружены отрицательные корреляции между между NO и TNF-α, уровнем МДА и показателями, характеризующими ФВД и степень бронхиальной обструкции. NO-продуцирующая функция дыхательных путей обусловлена мощной аккумуляций воспалительных клеток в респираторной системе и их высокой метаболической активностью, проявляющейся выработкой воспалительных и провоспалительных цитокинов, регулирующих иммунопатологическое реагиновое воспаление

Habitat characteristics as determinants of the local diversity and structure of coral reef fish communities

Habitat structure has a major influence on the composition of all animal\ud communities. In complex coral reef environments, a range of habitat features appear to\ud influence the structure of reef fish assemblages, with the effects of live coral cover and\ud topographic complexity receiving most attention. The role of coral diversity in\ud determining the structure of local fish communities and the consequences of species specific\ud fish-coral interactions in these ecosystems have not been fully explored. The\ud aim of this thesis was to investigate the relationships between coral reef fish\ud assemblages and habitat structure by sampling species-specific fish and coral\ud associations in the lagoon at Lizard Island on the Great Barrier Reef. Specifically, I\ud examined (a) the relative importance of coral cover, habitat topographic complexity and\ud coral diversity in explaining the structure of the local fish community, (b) the role of\ud different coral species in supporting diverse and abundant fish communities and, the\ud structural characteristics of coral species likely to be responsible for the observed\ud relationships, (c) the effects of sampling scale on the strength of the measured\ud associations between fish and corals, (d) patterns of habitat specialisation and habitat\ud overlap among the 14 co-existing damselfish species, and among ontogenetic stages.\ud The relationships between a range of habitat features and local fish diversity,\ud abundance and community structure were investigated by sampling over sixty 2m²\ud quadrats at three sites in the Lizard Island lagoon. Fish species richness, total abundance\ud and community structure were examined in relation to location within the lagoon and a\ud wide range of habitat variables, including topographic complexity, habitat diversity,\ud coral diversity, coral species richness, hard coral cover, branching coral cover and the\ud cover of corymbose corals. Fish species richness and total abundance were strongly\ud related to coral species richness and cover, but only weakly related to topographic\ud complexity. Regression tree analysis indicated that coral species richness accounted for\ud over 63% of the variation in fish species richness, while hard coral cover explained\ud more variation in total fish abundance (17.4%), than any other variable. The results\ud suggest that the diversity of scleractinian corals is critical in maintaining local coral reef\ud fish diversity, and loss of coral species will in turn lead to declining fish diversity.\ud \ud Further surveys were carried out to assess the relative importance of different\ud coral species in structuring fish communities, to identify the characteristics of corals\ud that support higher fish diversity, and to evaluate whether sampling scale has any effect\ud on the perceived strength of fish-habitat relationships. The communities of fishes\ud present on colonies of eight common coral species (Porites cylindrica, Echinopora\ud horrida, Hydnophora rigida, Stylophora pistillata, Seriatopora hystrix, Acropora\ud formosa, A. tenuis and A. millepora) were examined at three spatial scales of sampling\ud (2x2 m, 1x1 m, 0.5x0.5 m) at multiple sites in the Lizard Island lagoon. Coral species\ud was the only variable that explained significant amount of variation in fish species\ud richness among the samples. It also explained a significant amount of variation in total\ud fish abundance. Coral species explained more of the variability in fish species richness\ud (36-54%), than in fish abundance (10-15%). Colonies of E. horrida and H. rigida,\ud which exhibited an intermediate level of branching structure, supported more fish\ud species and individuals than similar sized colonies of all other coral species. Species of\ud coral with either very fine branching structure (A. millepora, A. tenuis, S. hystrix) or\ud very open branching structure (A. formosa), supported the lowest number of species and\ud individuals. The relationships between coral species and fish species richness or\ud abundance became stronger as the spatial scale of sampling increased. These results\ud indicate that the types of coral present on reefs can significantly influence the structure\ud of reef fish communities, and that coral species with an intermediate level of branching\ud structure support the most diverse and abundant fish communities. Furthermore, the\ud spatial scale of sampling can influence the perceived relationship between fish\ud communities and their habitats.\ud \ud The decline in fish diversity with coral diversity may be explained by habitat\ud specialisation and partitioning among reef fishes and/or common preferences for\ud particular corals that are susceptible to disturbance. These preferences may develop at\ud different life history stages. To test this, I examined species-specific habitat preferences\ud and ontogenetic habitat shifts among 14 co-occurring damselfish species in the Lizard\ud Island lagoon. The percent cover of 17 substratum types was estimated at four sites\ud within the lagoon: Palfrey Island, Lagoon centre, Lizard Head and Bird Island. The\ud habitat use of each damselfish species was then estimated by focal animal sampling\ud across the lagoon. Although live coral cover contributed only 26% of the substratum,\ud 28% of adults and 57% of new settlers were mostly found on live coral substratum,\ud indicating a strong preference for live coral habitat by these species. Some species\ud exhibited a high degree of habitat specialisation and low overlap in habitat use with\ud other species, which could help explain the importance of coral diversity on fish\ud community structure. In general, however, there was a substantial overlap within coral\ud associated and non-coral associated groups, with different species using similar\ud resources. Some species exhibited ontogenetic habitat shifts. In particular, new settlers\ud were commonly associated with finely branched corymbose corals, whereas adults were\ud more commonly linked to more open branching morphologies or non-coral substratum.\ud \ud The results from this study indicate a closer association between fish and coral\ud diversity than previously demonstrated. It suggests that human impacts on the\ud composition and diversity of coral communities are likely to have profound and\ud negative effects on reef fish biodiversity, more so than would be predicted on the basis\ud of declining coral cover or topographic complexity alone

Do anthropogenic changes to marine ecosystems result in the formation of ecological traps?

© 2017 Dr. Valeriya KomyakovaHuman activities such as overfishing, pollution and the introduction of invasive species have led to major changes in the marine environment. One of these anthropogenic impacts is the global proliferation of artificial structures for a variety of purposes, such as shoreline protection, wave and wind power stations, oil and gas platforms, and marinas. All of these structures have a secondary function: as habitat for marine organisms. Moreover, for generations, a large array of various types of purposely and accidently deployed artificial reefs have been used for the enhancement of recreational fisheries. More recently, planned and specially designed artificial reefs have also been used for management and conservation purposes, such as fish species protection, mediation of fisheries impacts, the redirection of fishing effort and habitat restoration. Regardless of the purposes of artificial reef deployment, all artificial reefs function as a habitat for marine species. Habitats play an important role in structuring animal communities, and poor habitat quality can be detrimental to the survival of animal populations. Therefore, for artificial reefs to be successful, it is vitally important that they mimic natural reef structure and community composition as closely as possible. Many artificial reefs have failed to achieve their goals, potentially due to inappropriate size, placing and design. Despite short coming in artificial reef design or placement they may still be selected as habitat by many marine fishes. The majority of marine fishes exhibit a pelagic larval stage that persists in the water column before settling onto a suitable habitat. Fish larvae use a combination of environmental cues to determine habitat suitability. Artificial reefs may mimic the habitat cues of a natural habitat but fail to provide adequate habitat diversity, complexity or the variety of other resources required for growth, reproduction, and survival. Preferential selection of an unfavourable habitat (i.e. a habitat that leads to lower fitness of individuals) is known as an "ecological trap". The ecological traps phenomenon has been relatively well documents in terrestrial environments for a large array of species. However, despite its importance for conservation and management of marine ecosystems, ecological traps have been poorly investigated in marine environments. The introduction of an artificial structure may cause the formation of an ecological trap through the provision of a seemingly suitable habitat that provides lower fitness advantages. Here, I investigated whether artificial reefs can act as ecological traps for fish populations and whether these effects may be reef design related. I examined temporal changes in fish community composition, recruitment rates and condition of individuals occupying different habitats (natural reefs, new design artificial reefs and Reef Ball reefs) at three locations in Port Phillip Bay, Victoria, Australia. Findings from CHAPTER TWO, where fish communities were compared between Reef Ball reefs and adjacent natural reefs, show that the performance of Reef Ball reefs as fish habitat greatly depends on the reef location and the type and quality of the adjacent natural reef. Generally, Reef Ball reefs supported richer fish communities than natural reefs, with the exception of one large continuous natural reef in Portarlington (Prince Georges Bank). However, Reef Ball reefs supported on average 75% lower fish abundances than natural reefs, with the exception of low-lying boulder field reefs like Altona natural reef and Portarlington Steele's Rocks reef. The community composition of all habitats across all locations were significantly different. CHAPTER THREE, where fish communities were monitored for two years on three habitats (Reef Ball reefs, adjacent natural reefs and new design artificial reefs) across three locations, provides further support for findings in CHAPTER TWO. However, it also illustrates that suitable design of the artificial reef may greatly improve its performance as fish habitat. While natural reefs supported up to thirty times higher fish abundances than both types of artificial reefs, new design artificial reefs on average supported twice as many species as natural reefs or Reef Ball reefs across all locations. Moreover, despite large dissimilarities in fish community structure between all three habitats, fish community composition was the most similar between natural reefs and new design artificial reefs, indicating that new design artificial reefs are closer mimics of the natural reefs in Port Phillip Bay, Victoria. CHAPTER FOUR investigates habitat preferences of three common reef fish species (Trachinops caudimaculatus, Vincentia conspersa and Trinorfoklia clarkei) through the observation of recruitment patterns to three study habitats and through laboratory based habitat choice experiments. The results of CHAPTER FOUR highlight differences in recruitment patterns and habitat preferences between different fish species. While some species recruit in higher numbers to natural reefs (T. caudimaculatus), others present no differences in recruitment patterns (T. clarkei) or recruit in higher numbers to Reef Ball reefs (V. conspersa), at least in some locations. These findings were corroborated by the laboratory experiments for T. caudimaculatus, as recruits selected Reef Ball reefs almost three times as often as the other two habitats, but not for V. conspersa, which showed no evidence for habitat preference. Finally, CHAPTER FIVE investigates consequences of these choices to individual performance. The results of CHAPTER FIVE demonstrate that responses by fishes to different types of artificial habitats are strongly species-, location- and habitat-specific. Instantaneous mortality rates obtained from fortnightly recruitment monitoring of T. caudimaculatus and mark-resighting experiments both indicate significantly higher mortality rates of this fish species on Reef Ball reefs and provide the first evidence of ecological trap formation in the marine environment. Generally, the higher condition of V. conspersa individuals on Reef Ball reefs indicates adaptive habitat selection for this fish species. In contrast, the higher condition of T. clarkei, combined with their lack of habitat preference, suggests, for the first time in a marine environment, the potential for the formation of a perceptual trap (when animals preferentially avoid high-quality habitat). Artificial reefs are excellent management tools of degraded habitats, recreational fisheries and for fish species conservation. However, poorly designed or poorly placed artificial reefs may lead to insufficient positive outcomes or even significant negative impacts on marine communities. Combined with their high costs, these effects may, in turn, lead to wasted resources and a negative community attitude towards future artificial reef deployments, which in turn could impede further management and conservation efforts