Mixed Habitats Research Articles

The Long-Term Dynamics of Shrew Communities: Is There a Downward Trend?

Compared to other small mammals, shrews are understudied due to their limited impact on agriculture, lower biomedical importance, and difficulty to study. Based on trapping data from 1975–2023, we investigated changes in Lithuanian shrews (Sorex araneus, Sorex minutus, Neomys fodiens, and Neomys milleri) over six decades. We analyzed the relative abundance of shrews and the proportion of their species within small mammal communities to assess temporal patterns and distribution in major habitat types. The first main finding was the confirmation of a decrease in S. araneus abundance in the 2020s compared to the 1990s and 2010s. The species proportion in 2020s was lower than in the 1970s–2000s; the decrease started in the 1980s and accelerated in the 2000s. Abundances and proportions of S. minutus and N. fodiens showed no significant trend. The abundance of N. fodiens was very low. The relative abundances and proportions of Sorex species were highest in commensal (human-related) and mixed (including forest, wetland, and meadow) habitats. Shrews were underrepresented in agricultural habitats, with the numbers of both S. araneus and S. minutus 4.1 times lower than expected. While the presence of S. minutus in commensal habitats could be explained by their diet specificity, the capture of N. fodiens and N. milleri in commensal habitats is a novel feature of their ecology.

Historical insights, current challenges: tracking marine biodiversity in an urban harbor ecosystem in the face of climate change

The Boston Harbor Islands is the only coastal drumlin archipelago in the USA, featuring a distinctive and uncommon geological intertidal habitat known as mixed coarse substrate, which supports a range of coastal species and ecological processes. Recently designated as one of America’s 11 most endangered historic places due to climate change impacts, coastal adaptation and restoration efforts are crucial to their preservation. Such efforts can benefit from historic and current knowledge of endemic and emergent biodiversity. To investigate broad trends in coastal biodiversity, we compiled an inventory of marine coastal macroalgae, macroinvertebrates, fish, mammals, and shorebirds observed in the harbor since 1861. Records span 159 years, consisting of 451 unique taxa from 19 phyla. Analysis of average taxonomic distinctness (AvTD) revealed increases in diversity towards the end of the twentieth and early twenty-first century, likely associated with improved water quality (dissolved oxygen; AvTD > 85, p = 0.01) due to harbor restoration in the 1980s. Macroinvertebrates comprised 50% of the records, making this the most diverse taxonomic group in the time series. A significant increase of non-indigenous species, primarily macroinvertebrates and macroalgae, was observed over the last 20 years near human infrastructure and across multiple islands, a consequence of global change and characteristic of most urban harbors. The mixed coarse intertidal habitat, which makes up > 70% of Boston Harbor’s inner islands and supports high macroinvertebrate and macroalgal diversity (47% of species records), is not routinely monitored; our findings serve as a foundational resource for climate adaptation projects and decision-making.

Association between Outlying Values in Body Condition Indices in Small Mammals and Their Habitats

Habitat type and habitat change are very important factors in the body condition of small mammals that inhabit them. The response can be positive, increasing, or the opposite, decreasing body condition. We analyzed outliers of the body condition indices (BCIs) of 12 species trapped in nine different habitats during 1980–2023 in Lithuania, a mid-latitude country. Mixed and fragmented habitats, as well as commensal habitats, could be considered the least suitable for small mammals, based on the highest proportions of underfit and low proportions of best-fit individuals. On the contrary, meadows and disturbed habitats (landfills and cormorant colonies) had the highest proportions of best-fit individuals, while the proportion of under-fit individuals was much lower than expected. We found outliers in the BCI in all species, except for the under-fit harvest mice (Micromys minutus), and in all habitats, though not numerous. The presence of the highest BCI in yellow-necked mice (Apodemus flavicollis) and bank voles (Clethrionomys glareolus) in the disturbed habitats studied and in house mice (Mus musculus) in commensal habitats may be related to the resources provided by these habitats. Our results demonstrate the feasibility of using retrospective small mammal morphometric data to analyze their relationship with habitat.

Habitat and Body Condition of Small Mammals in a Country at Mid-Latitude

The relationship between the body condition of different small mammal species and the habitat they occupy is poorly analyzed. We analyzed the body condition index, BCI, of 18 small mammal species trapped in forest, shrub, wetland, meadow, riparian, mixed and fragmented, disturbed, agricultural, and commensal habitats of Lithuania during the span of 1980–2023. The composition of small mammal communities was habitat-dependent, being richest in meadows, with eighteen species, and poorest in riparian habitats, with nine species. A significant variation in the BCI with respect to habitat was observed in eight small mammal species (Sorex araneus, S. minutus, Apodemus agrarius, A. flavicollis, Clethrionomys glareolus, Alexandromys oeconomus, Microtus agrestis, and M. arvalis). The highest average BCI for most of these species was found in disturbed habitats, with S. minutus and M. arvalis showing the highest BCI in agricultural habitats. The lowest average BCI for most species was found in mixed habitats, while C. glareolus and M. arvalis exhibited the lowest BCI in shrub habitats. In general, species dominating certain habitats did not have the highest BCI. This is the first multi-species, multi-habitat study of body condition in small mammals at mid-latitudes.

Does habitat modification impact morphology, performance, and inflammatory responses in an amphibian with limited dispersal capacity (Lisssotriton helveticus)?

The environment of an organism exerts selective pressures that affect mobility, feeding, reproduction as well as predator-prey and conspecific interactions. Land use changes induced by human activities modify these selective pressures and may result in the adaptation of organisms. Amphibians are ectotherms that typically show a biphasic life cycle with an aquatic and terrestrial phase, which makes them particularly sensitive to environmental change. We studied the impact of habitat modifications on palmate newt populations in the Ile de France region across four types of habitats: urban, mixed, agricultural, and natural with at least two replicates for each habitat type. We measured the morphology of newts using callipers, quantified maximal running and swimming speed and acceleration using high-speed video recordings, and quantified the swelling of the hind limb linked to an inflammatory reaction. Our results show that in urban habitats, newts are larger and heavier and have a better body condition. Females, moreover, have a larger head in natural habitats, possibly due to diet specialisation of females during the breeding season. In mixed and agricultural habitats, newts have longer limbs and show a tendency to run faster, possibly associated with the selective pressures on movement in mixed habitats. Differences in inflammatory responses were observed between sexes but not habitat types. Overall, our results show differences in morphology and trends for differences in performance in newts living in different habitats suggesting that animals are adapting to human-induced changes in their environment.

Population Response to Habitat Management from an Endangered Galliform: The Pyrenean Grey Partridge Recovery Project in Lago de Sanabria (2000–2023)

The Pyrenean grey partridge (Perdix perdix hispaniensis) is an endangered and insufficiently studied galliform occurring in upland habitats dominated by shrublands in Spain, France, and Andorra. Aiming to develop tailored management to favour the species, we studied the effect of habitat management on a partridge population located in Zamora province within the Galician–Duero mountains as part of a long-term project promoted by the regional government (Junta Castilla y León). Management was based on carrying out conservation and recovery of optimal habitats through clearing shrublands (either plots or linear) distributed in a “core area” of 45 km2, conducting tracks with beaters and pointing dogs during autumn in three areas, and comparing the partridge abundance before (2000–2006) and after (2007–2023) management. Habitat management increased partridge abundance values in two areas (1.46 and 1.68 times higher) and had no effect on the remaining one. The pattern of grey partridge abundance during the study was irregular and not influenced by the weather, and the highest abundance values were reached 8–10 years after habitat measures were implemented for the first time. Habitat management allowed high autumn abundance to be reached (mean kilometre abundance values of 2.94 and 3.74 birds/km in two areas), while the mean number of birds per family group was not affected by management (nine birds/group). When aiming to recover Pyrenean grey partridge populations, habitat management should be based on the conservation and management of shrublands to provide mixed habitats in the medium and long term, ensuring regular partridge monitoring.

Seasonal and environmental factors contribute to the variation in the gut microbiome: A large-scale study of a small bird.

Environmental variation can shape the gut microbiome, but broad/large-scale data on among and within-population heterogeneity in the gut microbiome and the associated environmental factors of wild populations is lacking. Furthermore, previous studies have limited taxonomical coverage, and knowledge about wild avian gut microbiomes is still scarce. We investigated large-scale environmental variation in the gut microbiome of wild adult great tits across the species' European distribution range. We collected fecal samples to represent the gut microbiome and used the 16S rRNA gene sequencing to characterize the bacterial gut microbiome. Our results show that gut microbiome diversity is higher during winter and thatthere are compositional differences between winter and summer gut microbiomes. During winter, individuals inhabiting mixed forest habitat show higher gut microbiome diversity, whereas there was no similar association during summer. Also, temperature was found to be a small contributor to compositional differences in the gut microbiome. We did not find significant differences in the gut microbiome among populations, nor any association between latitude, rainfall and the gut microbiome. The results suggest that there is a seasonal change in wild avian gut microbiomes, but that there are still many unknown factors that shape the gut microbiome of wild bird populations.

Do nest sites limit wild honey bee colonies? Decoding swarm waggle dances to assess nest site availability

Abstract Nest sites are often considered to limit wild honey bee, Apis mellifera, colonies in Europe where wild colony densities are low (mean 0.26/km2). Nest site availability can be challenging to quantify directly, especially in urban areas and farmland where colonies nest in different substrates. Here we assess nest site availability indirectly across large areas (78.5 km2) of mixed habitat (67% farmland, 25% urban and 8% woodland) by decoding 3310 waggle dances produced by scouts on swarms. During summers of 2021 and 2022, 14 artificial swarms were set up in two study areas in East Sussex, England. Swarms advertised three to nine nest locations (mean of 5.5) at distances of 0.1–11.2 km (median 1.2 km) all within 0.4–15.2 daylight hours after dancing commenced (median 2.7). We estimated the total number of nest locations, including those not advertised, by quantifying the overlap in locations advertised by two swarms (a form of mark–recapture), which gave a mean density of approximately three nest sites per km2. The probability of swarms advertising nest sites per km2, calculated using simulations of dance variation, was an average of 42% higher in urban areas (0.018/km2), 78% higher in woodland (0.023/km2) and 12% lower in farmland (0.011/km2) than random expectation. After controlling for distance, swarms were still more likely than expected to advertise nest sites in woodland but only in one study area. Our results indicate that nest sites do not limit wild colonies in the study areas given that our conservative estimate of nest site density (3/km2) exceeds the density of wild colonies on nearby landed estates (2/km2) and other locations in Europe (0.26/km2).

Structure of the assemblage of fruit-feeding butterflies in a high Andean anthropogenic landscape

The high Andean mountains are ecosystems subject to high human pressure activities, resulting in disturbed areas increasingly dominating the landscapes. However, there needs to have more knowledge about the contributions of different vegetation coverages and species to global diversity at the local level. For three consecutive years, we studied a guild of fruit-feeding butterflies in four different land covers (cloud forests, paramo, mixed anthropogenic habitats, and cattle pastures) in the northern Andes in Colombia, analyzing the diversity and structure of the butterfly assemblage in the region. The assembly showed significant differences between land covers. The mixed habitat was the most diverse in order q1 (exponential of Shannon entropy) and q2 (inverse of Gini-Simpson dominance index) diversity, and the cloud forest contained the higher abundance and species richness. Abundance decreased from forest to pasture, significantly reducing diversity in pastures, with cloud forest and paramo containing the key endemic species. These results indicate the value of landscape diversity in providing resources and conditions required for the diversity conservation of high Andean butterflies.

Quantifying uncertainty when extrapolating the relationship between snorkel counts and mark-recapture estimates of juvenile salmonids

Snorkel surveys are frequently used to monitor stream-dwelling fish. Inferring local abundance from snorkel surveys is complicated by two primary factors: variable fish detection probabilities and the relative abundance of fish in habitat types below the recommended minimum depth for snorkeling. We examine these factors across three salmonid species ( Oncorhynchus spp .), 4 years, and 113 location-years in Oregon coastal streams. We calibrate snorkel counts to mark-recapture estimates and develop mathematically explicit expressions that convert a new snorkel count into a probability density of abundance for streams containing mixed habitat types that were and were not snorkeled. Snorkelers detected 63%, 47%, and 39% of juvenile coho salmon ( Oncorhynchus kitsutch), steelhead trout ( Oncorhynchus mykiss), and cutthroat trout ( Oncorhynchus clarkii clarkia) estimated by mark-recapture, respectively, but uncertainty within and among sampling units was high. Further, analytics developed here can be used to infer abundance and uncertainty for habitat types that were not snorkeled. Our quantification of uncertainty arising from using snorkel counts as a proxy for abundance will help managers balance biological risks with available resources.

Culicoides Midge Abundance across Years: Modeling Inter-Annual Variation for an Avian Feeder and a Candidate Vector of Hemorrhagic Diseases in Farmed Wildlife

(1) Background: Epizootic hemorrhagic disease virus (EHDV) and bluetongue virus (BTV) are orbiviruses that cause hemorrhagic disease (HD) with significant economic and population health impacts on domestic livestock and wildlife. In the United States, white-tailed deer (Odocoileus virginianus) are particularly susceptible to these viruses and are a frequent blood meal host for various species of Culicoides biting midges (Diptera: Ceratopogonidae) that transmit orbiviruses. The species of Culicoides that transmit EHDV and BTV vary between regions, and larval habitats can differ widely between vector species. Understanding how midges are distributed across landscapes can inform HD virus transmission risk on a local scale, allowing for improved animal management plans to avoid suspected high-risk areas or target these areas for insecticide control. (2) Methods: We used occupancy modeling to estimate the abundance of gravid (egg-laden) and parous (most likely to transmit the virus) females of two putative vector species, C. stellifer and C. venustus, and one species, C. haematopotus, that was not considered a putative vector. We developed a universal model to determine habitat preferences, then mapped a predicted weekly midge abundance during the HD transmission seasons in 2015 (July–October) and 2016 (May–October) in Florida. (3) Results: We found differences in habitat preferences and spatial distribution between the parous and gravid states for C. haematopotus and C. stellifer. Gravid midges preferred areas close to water on the border of well and poorly drained soil. They also preferred mixed bottomland hardwood habitats, whereas parous midges appeared less selective of habitat. (4) Conclusions: If C. stellifer is confirmed as an EHDV vector in this region, the distinct spatial and abundance patterns between species and physiological states suggest that the HD risk is non-random across the study area.

Influence of Fly Ash on Soil Properties and Vegetation of Fresh Coniferous Forest during Long-Term Observation

Fly ashes produced in huge amounts during coal combustion requires proper management. The purpose of this study was to determine the impact of fly ash from burning hard coal used in large doses (250, 500, 1000 and 2000 t ha−1) on soil properties and vegetation of fresh mixed coniferous forest within 43 years from the ash application. The experiment was established in the Podzols in the forest habitat of Czułów, Katowice Forest district, Upper Silesia, Poland. Eight tree species were planted in ridges created by ploughing: Pinus sylvestris, P. nigra, Larix decidua, Betula pendula, Quercus robur, Q., Acer pseudoplatanus and Fagus sylvatica. The changes in soil morphology caused significant transformations in the physical and chemical properties of the soil such as soil texture, pH, macronutrients (P, K and Mg) content and C:N ratio. Increasing of ash doses changed the granulometric composition of the soil levels from loamy sand (250 t/ha−1) to silt loam (2000 t ha−1). Initially, the acidic Podzols were alkalized under the influence of the fly ash and then acidified, possibly due to the impact of accumulated litter layers, and the reaction of organic soil horizons changed from strongly acidic (250–1000 t ha−1) to alkalis (2000 t/ha−1). The macronutrients content increased in proportion to the fly ash dose, but the subsequent acidification resulted in a gradual decrease in the macronutrients share in the soil layers. The value of the C:N ratio grew after the ash application and then it gradually reduced, even by half. The transformations of soil horizons’ properties also increased the capacity of the soil sorption complex (CEC). All these processes led to a change in the trophic status of the habitat expressed by the soil habitat index (SIG) and the initial coniferous forest site can be classified as a mixed forest habitat even with the lowest ash dose used. The composition of plant communities developed forty years after the ash application was similar at the lower ash doses and the most frequent and abundant tree species were L. decidua, P. nigra and P. silvestris. B. pendula was previously co-dominant, but it was eliminated from the tree stands during the experiment. Planted trees characteristic of late stages of succession, such as Q. robur, Q. rubra, F. sylvatica and A. pseudoplatanus either did not survive or remained in very low quantities. The herb and moss layers developed in the process of spontaneous colonization, and together with the trees led to phytostabilisation of the bare substrates. After acidification of the topsoil horizons, the herb layers consisted mostly of coniferous, mixed, and deciduous forest species, and the most frequent or abundant were Lysimachia europea and Pteridium aquilinum. The moss layers were represented by coniferous forest flora. At the ash dose of 2000 t ha−1, Tilia cordata settled in one of the seral stages of spontaneous succession and this species dominated in the community and formed a dense tree stand. After the soil acidification, a shift from calcicole to calcifuge plant strategy took place among species of the herbaceous layer. The transformations of plant communities’ composition occurred in relation to changes in the soil properties.

Bark‐beetle disturbance severity only moderately alters forest affinity of arthropod communities

Abstract Forest ecosystems are facing increasing challenges like natural disturbances. Despite positive disturbance impacts on the diversity of several taxonomic groups, there are still concerns, whether the drastic canopy opening can lead to a turnover from forest to open habitat species. We sampled arthropods along a disturbance gradient in Norway spruce (Picea abies)‐dominated protected areas across Central Europe using Malaise traps and metabarcoding. To analyse changes in arthropod communities in terms of forest affinities along the disturbance gradient, we explored the potential of a list of forest affinities (LFA) that provides information about species affinities from closed forest to open habitats. Our results show that the mean forest affinity decreased with increasing disturbance severity. This trend was accompanied by a decrease in forest‐associated species as well as community shifts for open and mixed habitat species. Responses varied between taxa and were most apparent in Coleoptera. Overall, the changes did not come with a complete replacement of forest specialists by species with higher affinities for mixed and open landscapes nor a drastic loss of forest species. Furthermore, we observed severely disturbed plots with a high mean forest affinity and vice versa, which calls for further studies using these kinds of species classifications. The LFA can provide additional information how species associated with forests habitats can react to environmental changes beyond increasing amounts of deadwood resources. Using additional trapping methods and determination techniques might increase the explanatory power of such analyses along ecological gradients.

New sivatheriine giraffid (Ruminantia, Mammalia) craniodental material from the Siwaliks of Pakistan

ABSTRACT We present a new taxonomic study of fossil giraffids from the Siwaliks of Pakistan. The recovered material belongs to the family Giraffidae and includes a cranium of Vishnutherium priscillum, maxillary isolated cheek teeth of Bramatherium grande, maxillary isolated cheek teeth and mandibular fragments of Bramatherium megacephalum. These specimens were collected from the localities of Dhok Bun Ameer Khatoon, Chakwal district, and Hasnot, Jhelum district, Punjab, Pakistan. These outcrops belong to the Chinji Formation and Dhok Pathan Formation, respectively, of lower to middle Siwaliks, dated as Middle to Late Miocene in age. The presence of fossil fauna that primarily fed on herbaceous, grassy, and bushy vegetation suggests that both Dhok Bun Ameer Khatoon and Hasnot were dominated by mixed woodland habitats. These localities have a very rich fossil fauna and the cranium of Vishnutherium priscillum is the first that has been reported from Dhok Bun Ameer Khatoon.

Environmental characterization and cartographic modeling of wild plant habitats at the northern coastal zone of Egypt

Assessing natural vegetation through conventional methods faces considerable constraints, such as limited geographical scope, reduced precision, a lack of historical data, high expenses and time demands. The study aims to use environmental and spectral data to identify and map natural vegetation and plant species along the Mediterranean coast of Egypt. This involves employing spatial analyses and cartographic modeling techniques, marking an initial effort in this endeavor. To fulfill this aim, a total number of 70 wild plant habitats were surveyed and sampled for further laboratory identification of plant species. Multispectral and thermal bands of Landsat imagery were processed to generate land cover map, as well as calculate Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) to be integrated with the naturally grown plants in a cartographic model to predict the wild plant habitats. Coastal wild plant habitats were sparsely located and associated with a vegetation density ranging from 0.096 to 0.280 with an average of 0.167. Besides, the LST of these habitats fluctuated from 30.559 to 38.652 with an average of 34.361°C. Although the wild plant habitats at the Northern coastal region of Egypt are similar in environmental and climatic conditions, there are variability in NDVI and LST of each single habitat (pure or mixed). On the other hand, the lowest LST were associated with Erodium laciniatum/Rumex pictus and Erodium laciniatum habitats reporting 30.559 and 30.741°C, respectively. However, Lotus halophilus mixed with Ifloga spicata habitats reported the highest LST (38.652°C). The high vegetation density is mainly characterized by low LST which indicates the mixed wild plant habitats. The developed cartographic model showed a narrow strip along the Mediterranean region as highly suitable habitats for wild plant growth. The model can be used to map pure and mixed habitats of various wild plants with an accuracy exceeding 90%. The model was applied for mapping Arthrocnemum macrostachyum showing that the middle coastal region is most suitable for its growth. It’s recommended to integrate remotely sensed data with spatial analyses for the environmental analyses of natural plants. Present findings support researchers and scientists interested in environmental, botanic, and medical studies.

Floristic composition of the local family forest in Panarung Village, a subdistrict of Bentian Besar, West Kutai Regency, East Kalimantan, Indonesia

Ulin (Eusideroxylon zwageri T et B.) is a unique tree species in Kalimantan because its most durable wood and only grows in mixed lowland dipterocarp forest habitat. The purpose of this study is to examine the floristic composition, variety, and structure of the mixed ulin forest in Penarung village, subdistrict of Bentian Besar, West Kutai Regency, East Kalimantan. Each sample plot was rectangular and was 125 m by 20 m in size. For the tree stage, each sample plot was divided into subplots that measured 25 m by 20 m. Each subplot measured 2 m by 2 m for seedlings, thickets, and herbs and 5 m by 5 m for saplings The Result showed the species richness was 196 species, which consisted of 147 tree species, 16 species of lianas, 13 species of herbs, 12 species of shrubs, 5 species of ferns, 2 species of rattan and 1 species of palm. The tree stage consisted of 97 species, 70 genera, and 36 families. Species diversity (H’), showed that tree and sapling stages were high 3.82 for tree and 3.92 for sapling stages, while seedlings in moderate, with H’= 2.49. Evenness (E) in the tree stage was 0.83, while sapling and seedling were 0.87 and 0.55 respectively. This forest contained 28 species of endemic, 2 species of critically endangered (CR), 2 species endangered (EN), and 10 species of vulnerable (Vu).

Comparison of Soil Arthropod Diversity and Community Structure in Various Types of Land Cover in Malang Region, East Java, Indonesia

Land cover heterogeneity can affect the structure of biodiversity in the supplied niche, so it is necessary to know the taxa community. This study aimed to understand the effect of land cover variation on the diversity and community structure of soil arthropods. The types of habitats used include urban areas, agroforestry, gardens, and natural forests which are determined in the Malang Region, East Java, Indonesia. Hand sorting and hay bait traps were applied in this study to obtain a variety of arthropod soils and the Berlese-Tullgren funnel was used to extract them. As a result, there are 25 families from 15 orders collected based on their ecological roles. The abundance of Philoscidae in sites S1 and S2 (urban green space), Talitridae in site S6 (agroforestry), and Isotomidae in sites S3, S4, and S5 (highland mixed forest) was highest and dominant. Site S7 has the highest diversity (H' = 2.56; 1-D = 0.90; J' = 0.76) even though its family richness is lower. The site S3 counter-site had relatively high taxa richness (TR = 13), but low diversity (H' = 1.02; 1-D = 0.39; J' = 0.16). Based on clustering analysis and NMDS ordination, 3 classifications of habitat types were obtained, namely I (S6 & S7), II (S3, S4 & S5), and III (S1 & S2). Mixed forest habitats contain a more complex diversity of soil arthropods, which can serve as a model for improving the fertility of disturbed ecosystems.

The New History of Urbanization Representation: Another Face of New Century Novels

From de-urbanization to urbanization, China has created a new history, it has mainly undergone a gradual transition from integration to diversification. Based on the actual cities in China in the new century after reform and opening up, one period of time which born at the end of 1978, we tend to interrogate the urban novel for corresponding to rural novel, is a reflection on cultural integration and de-urbanization. From three aspects including the transcendence of modernity, the urban and rural spatial narrative of new century novels and the presentation of urban landscapes, considering the recursive reality from rural China to urban China, we attempt to explore how the novel text represents China's urbanization, dig out the manifestations of human’s survival in the process of urbanization in China in the new century after seeking roots in rural areas, thus mirroring the mixed urban habitats of multiple ethnic groups in Guangxi.

Population dynamics of the long-snouted seahorse (Hippocampus guttulatus Cuvier, 1829) in the Mar Menor coastal lagoon.

A 10-year monitoring program was developed to quantify the population dynamics of the long-snouted seahorse population in the Mar Menor coastal lagoon. Based on 985 underwater visual censuses, we estimated the long-snouted seahorse (Hippocampus guttulatus Cuvier, 1829) population size in the Mar Menor lagoon and its reduction in size in the last decades, as well as the effect of eutrophication crises in 2016 and 2019 on the species. The annual recruitment for the 2013-2020 period was estimated by comparing the relative abundance of early seahorse life stages in the ichthyoplankton. The density ranged from 0.0458 specimens/m3 at the beginning of the sampling period to 0.0004 at the end, showing a statistically significant difference between the three analyzed periods (Hgl=2 = 14.0, p = 0.001). The long-snouted seahorse population from the Mar Menor lagoon exemplifies the impact of fishing activities and human pressure, especially euxinic episodes and habitat destruction. As a result of this, the Mar Menor population has decreased from several million specimens to a few thousand, in only three decades. This species showed considerable resilience, the seahorse population began to recover once fishing activity stopped. In contrast, the long-snouted seahorse showed high vulnerability to habitat loss and an episodic flooding event. Adult seahorses showed preferences for highly complex habitats, especially Caulerpa prolifera-Cymodocea nodosa mixed meadows and habitats of high complexity and anthropogenic origin, such as harbors, jetties, or breakwaters. In contrast, juvenile seahorses preferred monotonous seabeds with low complexity, such as the sandy beds that are characteristic of the Mar Menor lagoon littoral.

Seasonal dynamics of a glycan-degrading flavobacterial genus in a tidally mixed coastal temperate habitat.

Coastal marine habitats constitute hotspots of primary productivity. In temperate regions, this is due both to massive phytoplankton blooms and dense colonisation by macroalgae that mostly store carbon as glycans, contributing substantially to local and global carbon sequestration. Because they control carbon and energy fluxes, algae-degrading microorganisms are crucial for coastal ecosystem functions. Environmental surveys revealed consistent seasonal dynamics of alga-associated bacterial assemblages, yet resolving what factors regulate the in situ abundance, growth rate and ecological functions of individual taxa remains a challenge. Here, we specifically investigated the seasonal dynamics of abundance and activity for a well-known alga-degrading marine flavobacterial genus in a tidally mixed coastal habitat of the Western English Channel. We show that members of the genus Zobellia are a stable, low-abundance component of healthy macroalgal microbiota and can also colonise particles in the water column. This genus undergoes recurring seasonal variations with higher abundances in winter, significantly associated to biotic and abiotic variables. Zobellia can become a dominant part of bacterial communities on decaying macroalgae, showing a strong activity and high estimated in situ growth rates. These results provide insights into the seasonal dynamics and environmental constraints driving natural populations of alga-degrading bacteria that influence coastal carbon cycling.