The structure and organization of acoustic signals arise through evolutionary processes and adaptive pressures on each species. During learning, natural or anthropogenic factors, such as high noise levels in urban areas, pose challenges to acoustic communication in birds. Many species adjust their acoustic signals to higher noise levels by increasing the frequency of vocalizations. The objectives of this study were to compare the dominant frequency of songs among birds dwelling in forest fragments distant from and near to urban areas, establish correlations between the dominant frequency of song and noise levels in these environments and verified the difference of response between oscines, suboscines and non-passerines. We recorded vocalizations of birds between July/2013 and November/2014 in four forest fragments, two of them near and two distant from urban areas. We used Audacity software to measure the dominant frequency. We measured the ambient noise by a calibrated sound pressure level meter in decibels (dBA) in each of the forest fragments. We analyzed 3740 vocalizations of nine tropical bird species. Forest fragments near to urban areas have higher noise levels than more distant forest fragments. Eight of nine studied species presented higher dominant frequencies of songs in forest fragments near to urban areas. Only one species, Myiothlypis flaveola, did not change the dominant frequency of song between the four analyzed forest fragments. The difference in dominant frequency between the forest fragments distant and closer to the urban areas did not vary between oscines, suboscines and non-passerines. Eight tropical birds exhibited higher dominant frequencies of song in forest fragments near urban areas with high level of ambient noise. Oscine, suboscine and non-passerine showed song variations. Bird species that have differences in the vocalization dominant frequency can be used in environmental monitoring and in ethological studies, as they are sensitive to high noise levels.Noise pollution caused by the vehicular traffic and urbanization are correlates with changes in the vocalization of tropical birds in forest fragments.

Mangroves are inter-tidal ecosystems with important global ecological roles. Today, mangroves around the world are at risk of fragmentation, especially in areas with rapid urbanization. Mangroves experiencing habitat fragmentation may be more intensely affected by human activities and a scenario that might have been ignored by previous studies on trace metal (TM) environmental geochemistry. Here, we investigated the typically fragmented habitats in a subtropical mangrove estuary (the Danshuei Basin in Taiwan Strait) to evaluate how human activities affect the geochemical behaviors of TMs. Ni, Sb, Zn, Cr, Cu, and Cd were the primary contaminants found in the mangrove patches. Metal sequestration from the riverine (Ni, Cr) and in-patch activity (Sb, Zn, Cu, Cd) are primary sources of TM’s risk. Using the synthesized pollution risk assessment, we showed that most of the mangrove patches are under moderate pollution risk. A significant relationship between the TMs pollution indicators and the absorption coefficient at 254 nm (a254), implying that the a254 could be a potential convenient parameter in the TMs risk assessment, which might be partly explained by the bio-remediation of sulfate-reduction microorganism. This study demonstrates the ecological risks posed by TM pollution on urban mangrove patches and emphasizes the importance of a more comprehensive survey for estuarine mangrove patch environments to achieve Sustainable Development Goals.

Litterfall is believed to be the major flux of Hg to soils in forested landscapes, yet much less is known about this input on tropical environment. The Hg litterfall flux was measured during one year in Atlantic Forest fragment, located within Rio de Janeiro urban perimeter, in the Southeastern region of Brazil. The results indicated a mean annual Hg concentration of 238 ± 52 ng g⁻¹ and a total annual Hg deposition of 184 ± 8.2 μg m⁻² y⁻¹. The negative correlation observed between rain precipitation and Hg concentrations is probably related to the higher photosynthetic activity observed during summer. The total Hg concentration in leaves from the most abundant species varied from 60 to 215 ng g⁻¹. Hg concentration showed a positive correlation with stomatal and trichomes densities. These characteristics support the hypothesis that Tropical Forest is an efficient mercury sink and litter plays a key role in Hg dynamics.

A superficial water quality survey in a watershed of the Paraíba do Sul River, the main water supply for the most populated cities of southeastern Brazil, was held in order to assess the impact of the expansion of agricultural activity in the near border of the Atlantic Rain Forest. The aim of this study was to investigate the presence of priority organochlorine pollutants in soils and superficial waters of Atlantic rainforest fragments in Teresópolis, Rio de Janeiro State. Soil sample preparations were compared by using ultrasound, microwave assisted extraction and Soxhlet extraction. Recoveries of matrix spiked samples ranged from 70 to 130%. Analysis of a certified soil material showed recoveries ranging from 71 to 234%. Although low concentrations of organochlorine residues were found in water and soil samples, this area is of environmental importance and concern, thus demanding a monitoring program of its compartments.

One of the causes of the global decline of amphibians is agricultural activity, responsible for causing habitat fragmentation and bringing a range of agrochemicals and fertilizers in the environment, compounds with a potential disrupting effect on non-target organisms, such as frogs. Exposure to these compounds has numerous harmful effects on the testes of these animals, which can compromise reproduction and, consequently, the maintenance of their communities. In this context, we compared the morphology and morphometry of the testes of three species of neotropical anurans (Physalaemus cuvieri, Dendropsophus minutus, and Boana albopunctata) from an agricultural area and a conservation unit. Histologically, the testicular morphology of the species was similar for both environments; however, morphometrically, there was a difference in the measured testicular parameters (locular area and area of spermatogenic cysts). Physalaemus cuvieri presented higher averages of locular and spermatogonial area in the agricultural environment, whereas the area occupied by the spermatozoa was smaller. Additionally, the testicular pigmentation, which is only present in this species, was greater in animal from the agricultural area. In D. minutus, the locular, spermatogonial, and sperm areas showed lower values in the agricultural area, whereas in B. albopunctata, the opposite pattern was found, with the area of the locule, spermatocytes, and spermatozoids being higher. Agricultural activities influence the testicular metric parameters in different species, and our results suggest that D. minutus is most sensitive to anthropic pressures. The least sensitive species is B. albopunctata. We highlight the importance of evaluating different species, since each species responds differently to agricultural activities.

We investigated lichen diversity in temperate oak forests using standardized protocols. Forty-eight sites were sampled in the Czech Republic, Slovakia and Hungary. The effects of natural environmental predictors and human influences on lichen diversity (lichen diversity value, species richness) were analysed by means of correlation tests. We found that lichen diversity responded differently to environmental predictors between two regions with different human impact. In the industrial region, air pollution was the strongest factor. In the agricultural to highly forested regions, lichen diversity was strongly influenced by forest age and forest fragmentation. We found that several natural factors can in some cases obscure the effect of human influences. Thus, factors of naturality gradient must be considered (both statistically and interpretively) when studying human impact on lichen diversity. We detected the different responses of lichens to ecological predictors in polluted and unpolluted areas.

An in-depth knowledge of solutes advection and turbulent diffusion is crucial to estimate dispersion area and retention time (tR) of pollutants within seagrass habitats. However, there is little knowledge on the influence of seagrass habitat fragmentation on such mechanisms. A set of dye tracer experiments and acoustic Doppler velocimeter measurements (ADV) were conducted. Solute transport conditions were compared in between fragmented (FM) vs homogeneous (HM) intertidal meadows, and in vertical gradients (canopy vs overlaying flow). Results showed the highest horizontal diffusion coefficient (Ky, c.a. 10⁻³m²s⁻¹) on FM and at the canopy-water column interface, whereas tR (2.6–5.6min) was not affected by fragmentation. It suggests that (1) FM are more vulnerable to pollution events in terms of dispersion area and (2) at low tide, advection rather than turbulent diffusion determines tR. Furthermore, Taylor’s theorem is revealed as a powerful tool to analyze vertical gradients on Ky within seagrass canopies.

The red-crowned crane (Grus japonensis) is an endangered bird species that has been listed as one of the Class I National Key Protected Wild Animals of China. This study analyzed the habitat changes in the two most important stopover sites for red-crowned crane (Liao River Estuary and Yellow River Delta National Nature Reserves) from 2000 to 2015. The results showed that the landscape patterns of the important stopover sites of red-crowned crane changed obviously and the potential suitable habitat area (tidal flats and marshland) for the red-crowned crane decreased by 183.3 km², while the area of human activities (including aquaculture waterbodies, farmland and artificial facilities) increased by 140.3 km². Landscape fragmentation intensified, which could has negative impacts on the survival of the red-crowned crane during migration. A comparative study confirmed that the reduction in marshlands and increasing landscape fragmentation caused by human activities were the main threats in the Liao River Estuary National Nature Reserve, while human activities and natural factors (such as channel flow, rainfall, and sediment discharge) were the jointly driving factors for the reduction in suitable habitats for red-crowned cranes in the Yellow River Delta National Nature Reserve. We suggest there are some loopholes in the management of the two nature reserves, which need to be strengthened urgently in China.

An iron ore pelletizing plant in southeastern Brazil exposes the tropical coastal ecosystems known as restinga to emissions of dust, iron solid particulate matter, and sulfur dioxide (SO₂). We aimed to assess the effects of those emissions on the leaf morphology and anatomy of the restinga species Byrsonima sericea, Cordia verbenacea, and Psidium guineense by evaluating visual symptomatology and analyzing the anatomical and micromorphological alterations resulting from exposure. Leaves were collected from individuals growing at two sites: a restinga forest fragment located 800 m away from the pelletizing plant and a restinga conservation unit 20 km away, which served as reference site. In all three species, individuals growing near the pelletizing plant showed necrotic regions on the leaf and foliar micromorphological alterations like turgor loss of epidermal cells, cuticle and epicuticular wax erosion, stomatal obliteration, and rupture and plasmolysis of trichomes. Anatomically, we found cell collapse, cell hypertrophy, and formation of a wound tissue. C. verbenacea showed the most severe visual and anatomical damage, being thus considered the most sensitive species to emissions. Leaf structural features such as uniseriate epidermis, lack of hypodermis, and presence of trichomes contributed to the highest sensitivity of C. verbenacea. Our findings reinforce the importance of performing morpho-anatomical studies to elucidate how leaf structure determines differential sensitivity to airborne pollutants in native species.

The bamboo flowering leads to the habitat fragmentation and food quality decline of a giant panda. Few empirical research has been conducted about the giant panda’s response to the bamboo flowering. Here, we investigated the characteristics of bamboo stands, giant panda’s activity, and selection and utilization of bamboo stands by giant panda in Taibaishan National Nature Reserve, China, over a 3-year period (September 2013–May 2016) during the Fargesia qinlingensis flowering period. Our results indicated that the proportion of whole bamboo stands flowering has gradually expanded from 26.7% in 2013 and 33.9% in 2014 to 52.3% in 2015. Although the flowering bamboo has lower crude protein and higher crude fiber than a non-flowering bamboo, the giant panda still fed on flowering bamboo from the evidence of droppings. The giant panda left its feeding sites and moved to the high elevation along river when the proportion of flowering reached 69.2% at elevation of 2350–2450 m in the third year. With the decline of the quality of bamboo stand of Fargesia qinlingensis, the giant panda abandoned its feeding sites when the threshold value of bamboo flowering reached 56.9–69.2%. Flexibility in foraging strategy and spatial behavior can help the giant panda to better adapt to the environment.