Do recreational activities affect macrofauna distribution pattern in Amazonian macrotidal sandy beaches?

Recreational activities are important source of disturbance on sandy beaches and have a negative effect on benthic communities as they alter species abundance, diversity, and/or distribution. Here, we report for the first time the effects of the recreational activities on the distribution pattern of macrobenthic communities of Amazonian sandy beaches. Sampling was performed during three consecutive months with different beach use intensity in 2017 (before, during vacation, and one month after the vacation period) on two contrasting beaches regarding disturbance (Urban: Atalaia; and Protected: Corvinas) in the intertidal zone along two equidistant transects at seven equidistant sampling stations: from the high-tide water mark to the swash zone. At each sampling station, four biological and sediment samples were randomly collected. Also, in each station, the sediment compaction was determined using a manual penetrometer. Physical sediment variables remained constant over time in both beaches, whereas differences were found in sediment compaction over the periods. Sediment compaction was considered the most important factor for the differences observed in macrobenthic community structure in the study beaches, and it was related to intensity of recreational activities. Variations in density and changes in richness between periods and sampling stations were observed in Atalaia beach. On the other hand, Corvinas beach remained the same throughout the study. Overall, three faunal zones were distinguished: upper intertidal, intermediate intertidal, and low-intertidal, whereas in the vacation period, only two faunal zones were distinguished: upper-intertidal and intermediate-low intertidal.

Do urban rivers in the amazon coast trap macroplastic?

Amazon Rivers are important sources of macroplastic that enter the oceans. The estimated macroplastic transport is still inaccurate as hydrodynamics are not considered and data are not collected in situ. The present study shows the first quantification of floating macroplastics at different temporal scales, and an annual transport estimate through urban rivers in the Amazon: the Acará and Guamá Rivers, which discharge into the Guajará Bay. We conducted visual observations of macroplastics (>2.5 cm) in different river discharges and tidal stages, and we measured current intensity and direction in the three rivers. We quantified 3481 floating macroplastics, which varied according to tidal cycle and seasonality. Although connected to and affected by the same tidal regime, the urban estuarine system had an import rate of 12 ton.y-1 through the Guamá River and an export rate of 21.7 ton.y-1 of macroplastics through the Guajará Bay, affected by local hydrodynamics.

Habitat use and nursery evaluation for the longnose stingray Hypanus guttatus (Bloch & Schneider, 1801) using vertebral microchemistry.

Here, we use vertebral microchemistry to investigate the habitat use patterns of the longnose stingray Hypanus guttatus in the northern and northeastern regions of Brazil, and to evaluate the existence of potential nurseries of the species. Samples were collected in Maranhão, Rio Grande do Norte and Pernambuco states between 2008 and 2019. Trace element concentrations of Ba:Ca, Mg:Ca, Mn:Ca and Sr:Ca in vertebrae were determined through laser ablation inductively coupled plasma mass spectrometry. We used one-step permutational ANOVAs to evaluate multi and single-element differences in element:Ca ratios among life stages and sexes across and within sites. Element signatures differed among all sites for both single and multi-element settings. However, there were few differences among life stages within sites, except for Mn:Ca between life stages for Maranhão state, and between sexes for Sr:Ca for both Pernambuco and Rio Grande do Norte, and Ba:Ca for Rio Grande do Norte. Furthermore, all multi and single-element analyses across locations were significant and highlight the strong differences by sites. We also performed a nonmetric multidimensional scaling analysis, which demonstrated the strong differences for samples from Rio Grande do Norte and the other two sites. By analysing the lifetime transects of each sample, we observed that there was little variation in all element:Ca ratios within sites. Therefore, we argue that the longnose stingray likely does not display extensive habitat use shifts and fulfils much of its life cycle within each area. Finally, we obtained no evidence of nurseries for any site and suggest this is likely a pattern across the species distribution. Future studies investigating habitat use with samples from larger specimens (disc width > 90 cm, >15 years) are needed to better understand the species habitat use patterns across all size ranges.

Recreational activities trigger changes in meiofauna and free-living nematodes on Amazonian macrotidal sandy beaches.

Sandy beaches are key economic assets worldwide, however, recreational activities are an important source of disturbance in these ecosystems. Intensive human use of beaches has a negative effect on benthic communities as it alters species abundance, diversity, and/or distribution. Here, we report the impacts of recreational activities (trampling and vehicles) on meiobenthic communities and nematode assemblages on Amazonian sandy beaches for the first time. For this purpose, samples were carried out in four consecutive months encompassing a period of high visitation peak (one month Before Vacation, During Vacation, and two months After Vacation) on three contrasting beaches regarding disturbances (Urban: Atalaia; Intermediary: Farol-Velho; and Protected: Corvinas) at seven equidistant sampling stations (50 m apart) from the high tide water mark to the swash zone. At each sampling station, three biological samples and sediments samples were collected haphazardly. Also, in each station, the sediment compaction was determined using a manual penetrometer. Overall, physical sediment variables (grain size, sorting) were constant over time in all beaches, whereas differences in intensity of recreational activities and sediment compaction were found between beaches and months. Sediment compaction was considered the most important factor for the differences observed in meiofauna community structure in the study areas, and it was related to intensity of recreational activities. Variations in density and changes in richness between periods were observed in Atalaia and Farol-Velho beaches. On the other hand, Corvinas beach remained the same throughout the study. In the first month after vacation, density and richness were similar to those in the period before vacation, thus indicating that the beaches had recovered in one month. Furthermore, vulnerabilities of Tardigrada and Copepoda, as well as of the Nematoda genera Daptonema, and Chromadorita, indicate that they might be potential indicators of recreational activities.

Beachgoer perceptions on health regulations of COVID-19 in two popular beaches on the Brazilian Amazon.

The sandy beaches of the Brazilian Amazon coast have enormous touristic potential and attract thousands of visitors each year, principally in July, at the beginning of the summer vacation period. In 2020, beach going was affected worldwide by the Covid-19 pandemic, but how did the pandemic affect recreational beach use on the Amazon coast in the Brazilian state of Pará? Given this, the objective of this work is to identify public perception in compliance with health safety established by authorities due to COVID-19 pandemic in two popular beaches on the Brazilian Amazon. Recreational patterns on the beaches of this region were analyzed from the user's perspective in July, through semi-structured interviews and direct observations. Recreational activities were prohibited on the beaches located within protected areas. At other locations, however, including Ajuruteua and Atalaia, the beaches were reopened on July 1 st, and both sites received thousands of visitors in July, despite the fact that interviewees believed the pandemic to be dangerous, and considered the situation in Pará state to be at least as bad or worse than in previous months. Agglomerations were verified on both study beaches and social distancing and other protective measures were limited. The increase in the new cases recorded in August was due to the relaxation of restrictions on social, recreational, and economic activities by the local authorities in July 2020, including the reopening of public access to beaches. As Pará state has been hard-hit by the pandemic, prohibitions on recreational beach use should clearly not have been lifted during this period. A number of management measures were presented in this study. These measures should contribute to the prevention of the spread of the virus during the upcoming public holidays, as long as the pandemic continues.

Intertidal benthic macrofauna of rare rocky fragments in the Amazon region / Macrofauna bentónica intermareal de los fragmentos rocosos raros en la región Amazónica

Rock fragment fields are important habitat for biodiversity maintenance in coastal regions, particularly when located in protected areas dominated by soft sediments. Researches in this habitat have received surprisingly little attention on the Amazon Coast, despite rock fragments provide refuges, nursery grounds and food sources for a variety of benthic species. The present survey describes the mobile macroinvertebrate species composition and richness of the intertidal rocky fragments in Areuá Island within the “Mãe Grande de Curuçá” Marine Extractive Reserve (RESEX) on the Brazilian Amazon Coast. Samples were collected during the dry (August and November 2009) and rainy seasons (March and May 2010) on the upper and lower intertidal zone, using a 625cm² quadrat. At each season and intertidal zone, macroinvertebrate samples were collected along four transects (20m each) parallel to the waterline, and within each transect two quadrats were randomly sampled. Macroinvertebrates were identified, density determined, and biomass values obtained to characterize benthic diversity from the rocky fragments. The Jackknife procedure was used to estimate species richness from different intertidal zones during the dry and rainy seasons. Macrofaunal community comprised 85 taxa, with 17 “unique” taxa, 40 taxa were common to both intertidal zones and seasons, and 23 taxa have been recorded for the first time on the Brazilian Amazon Coast. Species richness was estimated at 106±9.7 taxa and results suggest that sampling effort was representative. Polychaeta was the most dominant in species number, followed by Malacostraca and Gastropoda. Regarding frequency of occurrence, Crustacean species Dynamenella tropica, Parhyale sp. and Petrolisthes armatus were the most frequent representing >75% of frequency of occurrence and 39 taxa were least frequent representing <5% of frequency of occurrence. Occurrence of crustaceans and polychaetes were particularly noteworthy in all intertidal zones and seasons, represented by 15 and 13 taxa, respectively. The most representative class in abundance and biomass was Malacostraca that represented more than half of all individuals sampled, and was dominated by Petrolisthes armatus. The latter was one of the most frequent, numerous and higher biomass species in the samples. In general, results indicated greater richness and biomass in the lower zone. Additionally, richness and density increase during the rainy season. Rock fragment fields in Areuá Island are rich in microhabitats and include a diverse array of species in a limited area. Our results underline the importance of rock fragment fields in Areuá Island for the maintenance of biodiversity in the Amazon Coast.

Los fragmentos rocosos comprenden un hábitat importante para el mantenimiento de la biodiversidad en las regiones costeras, particularmente cuando estos se encuentran en áreas protegidas dominadas por sedimentos blandos. A pesar de que los fragmentos rocosos proporcionan refugio, zonas de crianza y fuentes de alimento para una gran variedad de especies bentónicas, las investigaciones sobre este hábitat en la costa de la Amazonia han recibido poca atención. El presente estudio describe la composición de macroinvertebrados vágiles y la riqueza de especies en los fragmentos rocosos del intermareal de la isla Areuá en la Reserva Marina Extractiva (RESEX) “Mãe Grande de Curuçá”, en la costa brasileña de la Amazonia. Las muestras fueron recolectadas durante la estación seca (agosto y noviembre 2009) y de lluvias (marzo y mayo 2010) en dos zonas del intermareal (superior e inferior), con un cuadrante de 625cm². En cada zona del intermareal y por temporada se tomaron muestras de macroinvertebrados a lo largo de cuatro transectos (20m cada uno) dispuestos paralelamente a la línea de costa. Dos cuadrantes se muestrearon al azar dentro de cada transecto. Los macroinvertebrados recolectados fueron identificados y se determinó la densidad y la biomasa de organismos para caracterizar la diversidad bentónica de los fragmentos rocosos. La riqueza de especies de las dos zonas del intermareal durante las estaciones seca y de lluvias se estimó por el método de Jackknife. La comunidad de macroinvertebrados estuvo compuesta por 85 taxones, con 17 taxones “único”, 40 taxones fueron comunes para ambas zonas del intermareal y temporadas, y 23 taxones se reportaron por primera vez para la costa brasileña de la Amazonia. La riqueza de especies se estimó en 106±9.7 taxones, por lo que los resultados sugieren que el esfuerzo de muestreo fue representativo. La Clase Polychaeta dominó en número de especies, seguida por Malacostraca y Gasteropoda. Los crustaceos Dynamenella tropica, Parhyale sp. y Petrolisthes armatus fueron las más frecuentes, con una frecuencia de presencia >75% mientras que 39 taxones fueron los menos comunes, con una frecuencia de presencia <5%. La presencia de crustáceos y poliquetos fue particularmente notable en las dos zonas y temporadas, incluyeron 15 y 13 taxones, respectivamente. La Clase Malacostraca fue la más conspicua en términos de abundancia y biomasa, representó más de la mitad de todos los individuos recolectados, con dominio de Petrolisthes armatus. Esta especie fue una de las más numerosas, frecuentes y de mayor biomasa en las muestras. En general, los resultados indican que hay una mayor riqueza y biomasa en el intermareal inferior mientras que la riqueza y la densidad aumentan en la estación lluviosa. Los sectores con fragmentos rocosos en la isla Areuá son ricos en microhábitats e incluyen una gran variedad de especies en un área limitada. Nuestros resultados enfatizan la importancia de los sectores con fragmentos rocosos en la isla Areuá para el mantenimiento de la biodiversidad en la costa de la Amazonia.