Vegetation Habitat Research Articles

NEW DATA ON VEGETATION AND SOILS OF URUP (KURIL ISLANDS)

The article presents new data on the vegetation of the island of Urup (Kuril Islands) obtained during the research of the authors in 2019 and 2021. The characteristics of the main forest communities (Erman’s birch forests, willow forests and Pinus pumila thickets), as well as rock and mire vegetation and vegetation of disturbed habitats, are given. The ecological-phytocenotic classification of the studied communities has been refined or carried out for the first time, the tables of geobotanical descriptions for a number of associations are given. Patterns of vegetation distribution in river valleys are considered. It is shown that in the northern part of the island, in the vegetation cover of the Pacific side, the role of mires and shrub communities increases in comparison with the Okhotsk Sea side. The description of soils is given in connection with the plant communities formed on them. The reasons of the revealed regularities are discussed, in particular, the influence of the relief, cold oceanic winds and fogs on the vegetation cover of the island.

Aspects of the natural history of the Sertao lancehead Bothrops lutzi from Brazil

Bothrops lutzi is a secretive species mainly associated with the Cerrado, Carrasco and ecotonal areas of Cerrado-Caatinga vegetation. We gathered information about habitat use, diet and the parasites of this elusive species. The species was found exclusively in Carrasco vegetation habitats in the states of Piaui and Ceará, but not in the core Caatinga region. Bothrops lutzi appears to have a diet composed of invertebrates and small vertebrates, not changing during its ontogeny. Three endoparasites were identified, one of them, Oswaldofilaria sp., is the first record for a Bothrops spp.

Estimating Juvenile Salmon Estuarine Carrying Capacities to Support Restoration Planning and Evaluation

Estimating juvenile salmon habitat carrying capacities is a critical need for restoration planning. We assimilated more than 4500 unique estimates of published juvenile densities (e.g., fish/m2) in estuarine and floodplain habitats. These density data were categorized by species and life stage, habitat type, seasonal period, and geographic region to develop frequency statistics (e.g., 25th and 75th percentiles, or quartiles). These frequency statistics were then used in a habitat expansion approach to estimate carrying capacities based on habitat extent. We demonstrate the habitat expansion approach by applying the quantiles of observed juvenile Chinook salmon (Oncorhynchus tshawytscha) and coho salmon (O. kisutch) densities (fish/ha) to spatial data describing current, historical or potential, and predicted (based on seal level rise) habitat extents for 16 coastal Oregon estuaries to estimate carrying capacities. Current carrying capacities based on 75th percentile springtime (Apr–Jun) densities ranged from 2902 to 33,817 fish/delta for Chinook salmon and 2507 to 20,206 fish/delta for coho salmon. Historic carrying capacities during the peak rearing period (spring) ranged from 3869 to 71,844 fish/delta for Chinook salmon and 3201 to 38,337 fish/delta for coho salmon, representing a 3 to 72% loss in Chinook salmon capacity and 2 to 67% loss in coho salmon capacity. Estimated carrying capacities were predicted to decline by 2 to 54% with 1.4 m of sea level rise in systems that are projected to lose vegetated tidal wetland habitat, while a 1 to 320% increase in capacity was predicted for systems that are predicted to increase in area with sea level rise. Finally, we demonstrate how the carrying capacity estimates can be used to estimate changes in juvenile Chinook and coho salmon capacity following restoration, which can be used to both design and evaluate restoration projects.

Invasive Spartina alterniflora habitat forms high energy fluxes but low food web stability compared to adjacent native vegetated habitats

Invasive Spartina spp. mostly colonizes a bare tidal flat and then establishes a new vegetated habitat, where it promotes the productivity of local ecosystems. However, it was unclear whether the invasive habitat could well exhibit ecosystem functioning, e.g. how its high productivity propagates throughout the food web and whether it thereby develops a high food web stability relative to native vegetated habitats. By developing quantitative food webs for a long-established invasive Spartina alterniflora habitat and adjacent native salt marsh (Suaeda salsa) and seagrass (Zostera japonica) habitats in China's Yellow River Delta, we investigated the distributions of energy fluxes, assessed the stability of food webs, and investigated the net trophic effects between trophic groups by combining all direct and indirect trophic interactions. Results showed that the total energy flux in the invasive S. alterniflora habitat was comparable to that in the Z. japonica habitat, whereas 4.5 times higher than that in the S. salsa habitat. While, the invasive habitat had the lowest trophic transfer efficiencies. Food web stability in the invasive habitat was about 3 and 40 times lower than that in the S. salsa and Z. japonica habitats, respectively. Additionally, there were strong net effects caused by intermediate invertebrate species in the invasive habitat rather than by fish species in both native habitats. This study revealed the contradiction between the promotion of energy fluxes and the decrease of food web stability resulting from the invasion of S. alterniflora, which provides new insights into the community-based management of plant invasions.

Changes to the coastal flora of Wirral, Merseyside (v.c.58)

Changes over more than 200 years in the landscape, vegetation and flora of coastal habitats of the Wirral peninsula in north-western England are described. These include the creation of new salt-marshes, following ongoing accretion of sediments as well as destruction of habitats following urbanisation and industrialisation. These changes led to the development of new Open Mosaic Habitats increasing floral diversity. The role of hybrids and new species to the Wirral coast is discussed in relation to changes in floral diversity with losses largely confined to species of totally destroyed and relatively nutrient poor habitats and occurring before 1900.

Crustaceans functional diversity in mangroves and adjacent mudflats of the Persian Gulf and Gulf of Oman

The effects of mangrove vegetation on functional features of crustacean assemblages were investigated using the Biological Traits Analysis (BTA). The study was carried out at four major sites in the arid mangrove ecosystem of the Persian Gulf and Gulf of Oman. Samples of Crustacea and associated environmental variables were taken seasonally (February 2018 and June 2019) from two habitats: a vegetated area with both mangrove trees and pneumatophores, and an adjacent mudflat. In each site, functional traits for the species were assigned using seven categories based on bioturbation, adult mobility, feeding habits and life-strategy traits. The results showed that the crabs (i.e., Opusia indica, Nasima dotilliformis and Ilyoplax frater) were widely distributed across all sites and habitats. The vegetated habitats supported higher taxonomic diversity than the mudflats, which highlights the importance of mangrove structural complexity for crustacean assemblages. Species inhabiting vegetated habitats were characterized by stronger presence of conveyor building species, detritivore, predator, grazer, lecithotrophic larval development, body size of 50–100 mm, and swimmer trait modalities. While, mudflat habitat enhanced the occurrences of surface deposit feeder, planktotrophic larval development, body size of <5 mm, and life span of 2–5 years. The results of our study showed that taxonomic diversity increased from the mudflats to the mangrove vegetated habitats. However, functional diversity did not differ between habitats. The significant differences in species and functional trait composition were observed between vegetated habitats and adjacent mudflats, stressing that different habitats may harbor different species and trait sets, likely as a result of habitat complexity. The use of taxonomic and functional attributes generate complementary information that can helps us to reach more efficient conclusions in terms of biodiversity conservation and ecosystem functionality in mangrove ecosystems.

Isolation, identification of entomopathogenic nematodes with insights into their distribution in the Syrian coast regions and virulence against Tuta absoluta.

The occurrence and distribution of entomopathogenic nematodes (EPNs) in the Syrian coast regions remain relatively uncharted. To address this gap in our knowledge, an extensive survey of these ecosystems was essential. This study aims to isolate and identify EPNs from diverse ecosystems within the coastal regions. The distribution of EPNs in cultivated and natural environments was analyzed according to habitat, altitude, and sampling season factors. Between 2017 and 2020, EPNs were recovered from 27 out of 821 soil samples (3.28%) and collected from 24 out of 375 sampling sites (6.4%). Based on morphological, morphometric, and molecular (ITS) characteristics, four EPN species were identified: Heterorhabditis indica (51.85%), representing the first report of its occurrence in the coastal regions, H. bacteriophora (33.33%), H. pakistanense (7.4%), which is also reported for the first time in Syria, and Steinernema affine (7.4%). There were statistical differences in the abundance and recovery frequency of EPNs in each type of habitat. Additionally, there were statistical differences in the altitude and sampling season recovery frequency. Co-inertia analysis revealed correlation between the distribution and occurrence of EPNs in vegetation habitats, altitude, and sampling seasons, as well as some soil characteristics. H. indica and H. bacteriophora were associated with citrus orchards, low-altitude ranges, moderate organic matter, and acidic soil. More specifically, H. indica isolates were correlated with olive orchards, vegetable fields, autumn season, and clay, sandy, and sandy loam soils. Meanwhile, H. bacteriophora isolates were correlated with tobacco fields, grasslands, alkaline pH, spring season, silty loam, and clay loam soils. H. pakistanense was linked to pear orchards, vineyards, moderate pH, and low organic matter. S. affine occurred in walnut orchards, silty soil, higher altitudes, and winter season. The virulence levels of three native EPN isolates (S. affine, H. indica and H. bacteriophora) were evaluated against 3rd and 4th instar larvae (outside and inside mines) and pupae of T. absoluta, a destructive pest in Syria. All three native EPN species exhibited ability to infect and kill the insect, with observed significant differences in their virulence. This study provides an understanding of EPN occurrence, distribution, and their potential for application in sustainable pest control strategies in Syria.

SPECIES DIVERSITY OF THE FLORA OF THE WESTERN HLYNIANSKA AREA OF THE DUBRIVSKE PRIMARY KAOLIN DEPOSIT

We describe the results of the study of the flora of regenerated and transformed vegetation on the territory of the Zahidno-Glynske section of the Dubrivske deposit of primary kaolin. The authors determined the species composition of higher vascular plants and mosses in the studied area. They made a brief analysis of the ecological features of the distribution of individual species or their systematic groups. They also made a short analysis of the ecological features of the distribution of individual species or their systematic groups. In particular, we established a connection between the features of the ecosystem structure and the ratios of representatives of different plant families, and also constructed a syntaxonomic scheme of plant groups based on the principles of the Brown- Blanke ecological and floristic school. During the research, we discovered 151 representatives of the flora. Among them are 143 species of higher vascular plants from 33 families and 9 species of mosses from 7 families. The most numerous are the families Poaceae (24 species), Asteraceae (21 species), Rosaceae (14 species), and Fabaceae (10 species). The vegetation of the studied area belongs to 13 classes, 19 orders, 35 unions, and 40 associations. There is an active restructuring of settlements with constant reformatting of the econiche packaging during the process of natural restoration of the vegetation cover with the help of primary autogenous successions. Empty econiches are formed here. They can potentially be inhabited, both by rare representatives of biota and habitats and by dangerous synanthropic species. For example, these habitats become vulnerable to the introduction of invasive species of transformers, which threaten rare biota components, ecosystem stability processes, agriculture, and human health. In this regard, territories, where active mineral extraction is carried out or restored after its termination, should be under constant monitoring regarding floristic and phytocenotic diversity. No species included in the IUCN Red List, the European Red List, annexes, and resolutions to the Berne Convention, Red Book of Ukraine, and to the list of regionally rare species were found on the territory. The invasive species-transformer Solidago canadensis was located on the territory. It is in the early stages of penetration and transformation of habitats of renewable natural vegetation.

Methane emissions offset atmospheric carbon dioxide uptake in coastal macroalgae, mixed vegetation and sediment ecosystems

Coastal ecosystems can efficiently remove carbon dioxide (CO2) from the atmosphere and are thus promoted for nature-based climate change mitigation. Natural methane (CH4) emissions from these ecosystems may counterbalance atmospheric CO2 uptake. Still, knowledge of mechanisms sustaining such CH4 emissions and their contribution to net radiative forcing remains scarce for globally prevalent macroalgae, mixed vegetation, and surrounding depositional sediment habitats. Here we show that these habitats emit CH4 in the range of 0.1 – 2.9 mg CH4 m−2 d−1 to the atmosphere, revealing in situ CH4 emissions from macroalgae that were sustained by divergent methanogenic archaea in anoxic microsites. Over an annual cycle, CO2-equivalent CH4 emissions offset 28 and 35% of the carbon sink capacity attributed to atmospheric CO2 uptake in the macroalgae and mixed vegetation habitats, respectively, and augment net CO2 release of unvegetated sediments by 57%. Accounting for CH4 alongside CO2 sea-air fluxes and identifying the mechanisms controlling these emissions is crucial to constrain the potential of coastal ecosystems as net atmospheric carbon sinks and develop informed climate mitigation strategies.

Environmental impact study of the NOOR 1 solar project on the Southern Region of Morocco

Morocco is leading the charge towards a more sustainable future through its investments in Renewable Energy. The NOOR 1 solar project in Ouarzazate serves as a shining example of this commitment, with a planned capacity of 160 MW and the potential to provide energy to over 1 million people. This study delves into the impact of this ground-breaking project on the environment and biodiversity in the southern region, as well as its role in combating global warming. The results show that the project has both positive and negative impacts, but its innovative concentrated solar power technology is the driving force behind these changes. Despite causing loss of native vegetation and wildlife habitat, changes to water resources and air quality, the NOOR 1 project also has many benefits such as reducing greenhouse gas emissions, enhancing energy security, providing economic benefits, improving access to electricity, and providing educational opportunities. The research emphasizes the crucial need to assess future renewable energy projects in a holistic manner, considering both environmental preservation and progress. This means taking into account both the positive and negative impacts that such projects may have on the environment and biodiversity and implementing measures to mitigate the negative impacts while maximizing the positive ones. The study suggests that a well-planned and executed renewable energy project can bring about significant benefits, such as increased energy security and economic benefits, while still being mindful of preserving the natural environment. By carefully balancing environmental preservation and progress, the study argues that renewable energy projects can help create a sustainable future for all.

EVALUATION OF COW MILK PRODUCTION DURING THE GRAZING PERIOD OF NATURA 2000 GRASSLAND HABITATS

In livestock development strategy, a country's permanent grasslands playan important role. After the pastoral value, green mass production and animal load of the Natura 2000 grassland habitats were broadly established, it was possible to assess milk production per hectare as the final productivityoutcome. Normal vegetation habitats 1530*, 2340*, 6150, 6210, 6240*, 62CO* and 6520 averaged 5.58 t/ha green matter (GM) with a loading of 0.57 cattle units (LU) per hectare in 150 days of grazing, a pastoral value (PV) of 38.1 and finally 3,250 liters of milk/hectare. Through the degradation of the grassy carpet, a part of Habitats 6150, 6240 and 6520 achieves approx. three times less namely 1.65 t/ha GM in 140 days of grazing with 0.18 LU/ha and 14.6 PV providing 1,160 l/ha cow's milk. The most valuable habitat is 6520, Mountain grasslands that produce almost 6,000 l/ha of cow's milk at 65 PV and 11.75 t/ha GMandtheleast productive is Habitat 2340* Pontic continental dunesthat produce 870 l/ha of cow'smilk. These data are used to draw up the arrangements and development strategy of the pastoral heritage.

The reproducibility of remotely piloted aircraft systems to monitor seasonal variation in submerged seagrass and estuarine habitats

Seasonal variation in seagrass growth and senescence affects the provision of ecosystem services and restoration efforts, requiring seasonal monitoring. Remotely piloted aircraft systems (RPAS) enable frequent high-resolution surveys at full-meadow scales. However, the reproducibility of RPAS surveys is challenged by varying environmental conditions, which are common in temperate estuarine systems. We surveyed three eelgrass ( Zostera marina) meadows in Newfoundland, Canada, using an RPAS equipped with a three-color band (red, green, blue [RGB]) camera, to evaluate the seasonal reproducibility of RPAS surveys and assess the effects of flight altitude (30–115 m) on classification accuracy. Habitat percent cover was estimated using supervised image classification and compared to corresponding estimates from snorkel quadrat surveys. Our results revealed inconsistent misclassification due to environmental variability and low spectral separability between habitats. This rendered differentiating between model misclassification versus actual changes in seagrass cover infeasible. Conflicting estimates in seagrass and macroalgae percent cover compared to snorkel estimates could not be corrected by decreasing the RPAS altitude. Instead, higher altitude surveys may be worth the trade-off of lower image resolution to avoid environmental conditions shifting mid-survey. We conclude that RPAS surveys using RGB imagery alone may be insufficient to discriminate seasonal changes in estuarine subtidal vegetated habitats.

Forest Stand Composition of the Tapanuli Orangutan (Pongo tapanuliensis) Habitat in the Nature Reserves

The Forest areas of Dolok Sipirok Nature Reserve (DSNR) and Dolok Sibual-Buali Nature Reserve (DBNR) are part of Batang Toru forest landscape which is also the habitat of some protected and endangered wildlife such as Tapanuli orangutans (Pongo tapanuliensis). However, the forest has continued to experience widespread pressure and degradation or reduction, mainly due to forest conversion. Therefore, it is very notable to assess the composition of forest vegetation of DSNR and DBNR considering their very important role for the survival of the Tapanuli orangutan populations. The composition of forest vegetation in this research is known by vegetation analysis. The method vegetation analysis used is line transect. The length of the line transect is 1000 m which consists of 10 plots of each transect with a distance between plots of 100 m. Measurements are carried out on the growth rate of seedlings, saplings, poles and trees. Furthermore, the processing of vegetation analysis data is carried out to find out the Important Value Index (IVI), diversity index (H’), evenness (E) and richness (d) of vegetation species in the research area. The results showed that the composition of orangutan habitat vegetation in DSNR consisted of 107 species from 39 families, while DBNR forest consisted of 117 species from 45 families. Tree Syzygium sp1. species consistently have the highest IVI scores at all forest vegetation growth rates of both reserves. The diversity, evenness and richness of DBNR forest vegetation species tends to be higher than DSNR forest.

Comparing Ant Assemblages and Functional Groups across Urban Habitats and Seasons in an East Asia Monsoon Climate Area.

China's East Asia monsoon zone is undergoing rapid land-use conversion and urbanization. Safeguarding remaining biodiversity requires reducing, mitigating, and/or eliminating the negative impacts of human-induced landscape modification. In this study, we sampled ground-dwelling ants at 40 plots over 12 continuous months in a suburban area in southwestern China to examine whether and how vegetation composition and habitat fragmentation affected species richness and assemblage composition for the general ant community and, specifically, for principal functional groups (including Opportunists and Generalized Myrmicinae). Warmer seasons were associated with a higher capture rate for all functional groups. Patterns of ant species richness among Opportunists were more sensitive to vegetation and fragmentation than for Generalized Myrmicinae, and these effects generally varied with season. Patterns of ant assemblage composition for Opportunists were exclusively sensitive to vegetation, whereas Generalized Myrmicinae were sensitive to both vegetation and fragmentation with variation among seasons. Overall, our findings highlight the important role of seasonality, vegetation composition, and habitat fragmentation in mediating the impacts of human-induced landscape modification on urbanized ant communities, which make an essential functional contribution to biodiversity in the East Asia monsoon zone.

Chemically mediated rheotaxis of endangered tri-spine horseshoe crab: potential dispersing mechanism to vegetated nursery habitats along the coast.

An enhanced understanding of larval ecology is fundamental to improve the management of locally depleted horseshoe crab populations in Asia. Recent studies in the northern Beibu Gulf, China demonstrated that nesting sites of Asian horseshoe crabs are typically close to their nursery beaches with high-density juveniles distributed around mangrove, seagrass and other structured habitats. A laboratory Y-maze chamber was used to test whether the dispersal of early-stage juvenile tri-spine horseshoe crab Tachypleus tridentatus is facilitated by chemical cues to approach suitable nursery habitats. The juvenile orientation to either side of the chamber containing controlled seawater or another with various vegetation cues, as well as their movement time, the largest distance and displacement were recorded. The juveniles preferred to orient toward seagrass Halophila beccarii cues when the concentration reached 0.5 g l-1, but ceased at 2 g l-1. The results can be interpreted as a shelter-seeking process to get closer to the preferred settlement habitats. However, the juveniles exhibited avoidance behaviors in the presence of mangrove Avicennia marina and invasive saltmarsh cordgrass Spartina alterniflora at 2 g l-1. The juveniles also spent less time moving in the presence of the A. marina cue, as well as reduced displacement in water containing the S. alterniflora cue at 1 and 2 g l-1. These results may explain the absence of juvenile T. tridentatus within densely vegetated areas, which have generally higher organic matter and hydrogen sulfide. Early-stage juvenile T. tridentatus are capable of detecting and responding to habitat chemical cues, which can help guide them to high-quality settlement habitats. Preserving and restoring seagrass beds in the intertidal areas should be prioritized when formulating habitat conservation and management initiatives for the declining horseshoe crab populations.

Ecological role of traditional graveyards in the persistence of Thalictrum petaloideum L. population in Korean limestone area

In order to examine the factors that contributed to the persistence of the population, we investigated the distribution of T. petaloideum in Korea. Vegetation environment, habitat type, phenology, self-compatibility and conservation status were evaluated in the limestone area with the most stable distribution of the population. The distribution of T. petaloideum was identified in the vegetation with low crown density, traditional Korean graveyards (TKG) and the edges of TKG. Among each type of the habitat, the population distributed at the edge of the TKG had the highest number of leaves, as well as had more seed per individual. The density of mature individuals was highest in the TKG, followed by the edge and limestone vegetation of the TKG. Therefore, it was evaluated that TKG functionate not only as a major habitat but also a site of seed source. After 40 days of flowering of T. petaloideum, the seeds matured, and the estivation started from the end of July. In the beginning of September, the second emergence of leaves started. The reason for T. petaloideum’s selecting TKG as the main habitat was presumed as a combined effect of annual growth patterns of the plant and Korean custom of managing graveyards.

First-season growth and food of YOY pike (Esox lucius) are habitat specific within a lake

Piscivorous fish are important predators in aquatic systems and as such they can have far-reaching effects on ecosystem composition and function. These effects depend on piscivore predation rates and behaviour, and recruitment of young-of-the-year fish into piscivory can hereby govern ecosystem properties. Growth and recruitment can differ between water bodies due to e.g. general productivity, but information on variation in juvenile growth and body condition between habitats within water bodies is scant. We here evaluate growth, body condition, food occurrence and stomach contents of an important piscivore, pike (Esox lucius), over the first growth season in two contrasting and spatially separated homogenous habitat types (emergent and submerged vegetation separated by 50 m of open sand) within the same lake. Individual size and body condition in pike were higher in the submerged vegetation early in the season, whereas by the end of their first summer pike were larger and in higher body condition in the emergent vegetation, in spite of occurrence of zooplankton, macroinvertebrates and fish prey being overall higher in the submerged vegetation. Pike showed habitat-specific patterns of macroinvertebrate consumption (higher in the submerged vegetation) and date-specific patterns of zooplankton (higher early in the season), macroinvertebrate (lower late in the season) and fish (higher later in the season) consumption that were not a result of occurrence of food types, as occurrence and consumption patterns did not match. We conclude that pike that hatched in the emergent vegetation habitat were larger towards the end of the season and, hence, these pike should have a higher survival probability and possibly contribute more to pike population density and predation at older ages, but also that submerged vegetation provides an alternative and added recruitment environment for pike in shallow lake ecosystems.

Tissue Oxidative Ecology along an Aridity Gradient in a Mammalian Subterranean Species.

Climate change has caused aridification which can alter habitat vegetation, soil and precipitation profiles potentially affecting resident species. Vegetation and soil profiles are important for subterranean mole-rats as increasing aridity causes soils to become harder and geophytes less evenly distributed, and the inter-geophyte distance increases. Mole-rats obtain all water and dietary requirements from geophytes, and thus digging in harder soils may amplify stressors (hyperthermia, dehydration- or exercise-induced damage). This study assessed the oxidative status of the wild common mole-rat along an aridity gradient (arid, semi-arid and mesic). Kidney and liver oxidative markers, including total oxidant status (TOS), total antioxidant capacity (TAC), oxidative stress index (OSI), malondialdehyde (MDA) and superoxide dismutase (SOD) were measured. Liver oxidative status did not demonstrate any significance with the degree of the aridity gradient. Aridity affected the TAC and OSI of the kidney, with individuals in the most arid habitats possessing the highest TAC. The evolution of increased group size to promote survival in African mole-rats in arid habitats may have resulted in the additional benefit of reduced oxidative stress in the kidneys. The SOD activity of the kidneys was higher than that of the liver with lower oxidative damage, suggesting this species pre-emptively protects its kidneys as these are important for water balance and retention.

Macroalgal physical structure predicts variation in some attributes of temperate fish assemblages better than macroalgal species composition

The importance of vegetative habitat in influencing distribution patterns, species interactions, and biodiversity is well documented in marine ecosystems, yet most previous studies on macroalgal–fish relationships have focused on influences of density and identity of macroalgae, often ignoring how the unique physical structure provided by each alga contributes to patterns. We tested whether the distribution, abundance, and biomass of rocky reef fishes could be predicted as well or better by measures of physical structure of macroalgae than by species identity and abundance. Divers visually sampled fishes and macroalgae at seven sites spread over several km at Santa Catalina Island, California, over a 1-year period, to examine how the distribution patterns of fishes related to spatiotemporal differences in the macroalgal assemblage. We found that variation in the composition, density, and diversity of the fish assemblage was equally or better explained by macroalgal structure (total surface area and height) than by macroalgal species density. In contrast, biomass and vertical distribution of fishes were better predicted by macroalgal species identity and density than by macroalgal physical structure. Of the macroalgal attributes, surface area was the best predictor of fish abundance and multivariate assemblage structure (species and their densities). However, much of the spatiotemporal variation in the fish assemblage was not explained by macroalgae, indicating that even in habitats visually dominated by macroalgae, macrophytes are only one of many factors that drive spatiotemporal variation in community structure. Our results suggest that quantifying the physical structure provided by marine macroalgae can be more useful than macroalgal species identity in predicting some aspects of fish assemblage structure.

Evaluating the effect of temperature on photosynthesis and respiration of articulated coralline algae using oxygen evolution and chlorophyll a fluorescence

Coralline algae form abundant and ecologically important submerged aquatic vegetation habitats throughout the world. However, algal performance is threatened by climate change and ocean acidification. Previous studies suggest that their photosynthetic performance will be compromised mainly at elevated temperatures. Understanding the impact of diverse climate change scenarios requires a clear and thorough comprehension of the photosynthetic response to temperature gradients. The objective of this study was to evaluate the short-term effect of temperature (10–35 °C) on the gross photosynthesis (GPS), respiration, and electron transport rates (ETRs) of 3 articulated coralline algae (Lithothrix aspergillum, Corallina officinalis, and Bossiella orbigniana) for a better understanding of their metabolism and to investigate the relationship between GPS and ETR as a function of temperature. The results showed that the coralline algal metabolism is highly sensitive to temperature, but responses were species-specific and can be related to their light adaptation/acclimation; the high-light-adapted L. aspergillum was least negatively affected. The photosynthesis to respiration ratio was optimal between 20 and 25 °C according to the local thermal regime but was significantly reduced toward higher temperatures, indicating strong carbon imbalances and highlighting the relevance of thermal stress for coralline algal performance. A strong correlation between GPS and ETR was found between 10 and 30 °C in all species, but both above saturation irradiances and at elevated temperatures (≥30 °C), a clear deviation from linearity occurred. This suggests that ETR is not a good proxy to estimate photosynthetic activity under light or thermal stress. This information should be useful for studies implementing global change scenarios and pulse amplitude modulated (PAM) fluorometry in coralline algae.