Effects of microplastics pollution on the abundance and composition of interstitial meiofauna

Introduction: Pollution by microplastics is a global problem in marine environments, which impacts microorganisms and ecosystems at several spatial levels. Sandy beaches are depositional environments where microplastics tend to accumulate in large quantities. The co-occurrence of interstitial meiofauna and microplastics in sand grains raises the question on whether the accumulation of microplastics in the sediments affects the abundance and composition of the meiofaunal communities. Objective: To test the hypothesis that microplastics affect the meiofauna of urban sandy beaches. Methods: We studied the three main urban sandy beaches of Santa Marta, Colombia: El Rodadero, Santa Marta Bay, and Taganga. All are similar in morphology and external pressures, and differ from other beaches in the region. In April 2019 we collected 81 sand samples, equally distributed in the intertidal zone (upper, mid, and lower intertidal levels). We applied generalized linear models to abundance, and multivariate permutational tests to community composition. Results: We identified 17 taxonomic groups of meiofauna, and microplastic particles (mainly 45-500 micron fibres) evenly distributed across beaches and intertidal levels. There was more meiofauna at the mid intertidal level, and in fine and medium grain sediment. At the lower intertidal level, sites with more microplastics had less meiofauna. Abundance of microplastics explained 39 % of the variation in meiofaunal community composition at lower intertidal levels. Conclusions: The accumulation of microplastics might have a negative impact on these meiofaunal interstitial communities. This is not surprising: if microplastics occupy the same physical space as these animals, they might presumably modify the structure of sediments and the composition of interstitial water.

Introducción: La contaminación por microplásticos es un problema global en los ecosistemas marinos, con impacto sobre microorganismos y ecosistemas en varios niveles espaciales. Las playas arenosas son ambientes de deposición donde se tiende a acumular gran cantidad de microplásticos. La co-ocurrencia de meiofauna intersticial y microplásticos en granos de arena plantea la pregunta de que si la acumulación de microplásticos en sedimentos afecta la abundancia y composición de comunidades de meiofauna. Objetivo: Probar la hipótesis de que microplásticos afectan la meiofauna de playas arenosas urbanas. Métodos: Estudiamos las tres principales playas arenosas urbanas de Santa Marta, Colombia: El Rodadero, Bahía Santa Marta y Taganga. Estas son similares en morfología y presiones externas, y difieren de las otras playas de la región. En abril 2019 recolectamos 81 muestras de arena, distribuidas de manera equidistante en la zona intermareal (nivel intermareal superior, medio y bajo). Aplicamos modelos lineales generalizados de abundancia, y pruebas permutacionales multivariantes a la composición de comunidades. Resultados: Identificamos 17 grupos taxonómicos de meiofauna, y partículas de microplástico (principalmente fibras de 45-500 micras) distribuidos equitativamente a lo largo de las playas y niveles intermareales. Hubo más meiofauna en el nivel intermareal medio, y en sedimentos de grano mediano y fino. A niveles intermareales más bajos, sitios con más microplásticos tuvieron menos meiofauna. La abundancia de los microplásticos explicó el 39 % de la variación en comunidades de meiofauna a niveles intermareales bajos. Conclusión: La acumulación de microplásticos podría tener un impacto negativo sobre las comunidades de meiofauna intersticial. Esto no es de sorprender: si los microplásticos ocupan el mismo volumen físico que estos animales, estos podrían presuntamente modificar la estructura de sedimentos y la composición del agua intersticial.

Interstitial annelids from the Caribbean Coast of Colombia / Anélidos intersticiales de la costa Caribe de Colombia

Abstract A total of 298 species of polychaetes have been recorded from Colombia. However, only the family Protodrilidae has been reported from the marine interstitial realm. We here aim at identifying the interstitial annelids inhabiting the sandy beaches in Santa Marta region to the most accurate taxonomic level based on light microscopy examinations. Our samples, collected from the intertidal zone at three touristic beaches in the department of Magdalena (Santa Marta Bay, Rodadero Bay, and Taganga Bay), yielded a total of 83 specimens, which we assigned to five families, ten genera and nine species. From those, two families, eight genera, and the species Hesionides gohari, Neogyptis mediterranea, Neopetitia amphophthalma, Westheidesyllis gesae, and Syllis beneliahuae represent new records for the Colombian fauna. This survey should be considered as a first step towards a complete knowledge of the Colombian diversity of interstitial annelids, and our results significantly contribute to fill the gap of our current knowledge, suggesting a high diversity of species comparable to this in better-known areas of the Caribbean and the Atlantic coasts of Brazil. A brief diagnosis, comments on distribution and ecology, and remarks are provided for each record, in order to facilitate the re-identification of the species. Rev. Biol. Trop. 66(2): 658-673. Epub 2018 June 01.

Resumen Un total de 298 especies de poliquetos han sido registradas para Colombia. Sin embargo, solo la familia Protodrilidae ha sido reportada para el medio marino intersticial. El objetivo de este estudio fue identificar los anélidos intersticiales que habitan en playas arenosas de la región de Santa Marta hasta la categoría taxonómica más precisa, basados en observaciones al microscopio de luz. Las muestras fueron recolectadas en la zona intermareal de tres playas turísticas en el departamento del Magdalena (La bahía de Santa Marta, bahía de Rodadero y bahía de Taganga), resultando un total de 83 especímenes, los cuales fueron asignados a cinco familias, diez géneros y nueve especies. De estos, dos familias, ocho géneros y las especies Hesionides gohari, Neogyptis mediterranea, Neopetitia amphothalma, Westheidesyllis gesae y Syllis beneliahuae representan nuevos registros para la fauna de Colombia. Este trabajo debería ser considerado como el primer paso hacia el conocimiento de la diversidad de anélidos intersticiales en Colombia y los resultados contribuyen significativamente a llenar el vacío de información en el tema, sugiriendo una alta diversidad de especies comparable con la de áreas mejor conocidas del Caribe y de la costa atlántica de Brasil. En este trabajo se provee una breve diagnosis, comentarios sobre la distribución y ecología, y anotaciones para cada registro, con el propósito de facilitar la re-identificación de las especies.

Presencia de microplásticos en cuatro playas arenosas de Perú

Se presenta el número y peso por metro cuadrado de fragmentos de microplásticos presentes en cuatro playas arenosas de la costa peruana. Las muestras fueron colectadas entre junio de 2014 y mayo 2015. Fragmentos de plástico duro mayores a 1 mm fueron encontrados en más del 80% de las muestras de las cuatro playas. La playa Costa Azul (~ 12°S) presentó 522 fragmentos por metro cuadrado (items/m²) de microplásticos, de los cuales, 463.33 items/m² y 2.6 g/m² fueron plásticos duros. La playa Albúfera de Medio Mundo (~ 11°S) presentó el menor número y peso de microplásticos (4.67 items/m² y 0.50 g/m²). Una muestra aleatoria de la playa Costa Azul fue analizada por el espectroscopio FT-IR. Se encontró 5 fragmentos con poliuretano (PE), dos fragmentos con polipropileno (PP) y un fragmento con estireno (EPS). Pocos estudios mencionan al plástico duro como la mayor fracción de los microplásticos, se sugiere nuevas fuentes de intrusión y vías de microbasura en los hábitas, los cuales podrían estar afectando desde la base de trama trófica marina en el Perú.

Results of measurement of the microplastic number and weigh from four sandy beaches along Peruvian coast are shown. Microplastic samples were collected during June 2014 to May 2015. Hard plastic fragment > 1 mm was found at over 80% of the four sampling locations. The Costa Azul beach (~ 12°S) presented the 522 items per m² of microplastic, in which the 463.33 items per m² and weight 2.6 g per m² were hard plastic. The Medio Mundo (~ 11°S) beach has the lowest microplastic in number and weight (4.67 items per m² and 0.50 g per m²). The random microplastic sample from Costal Azul beach was confirmed by FT-IR spectroscopy, we found five fragments with polyurethane (PE), two pieces with polypropylene (PP) and one piece of Styrofoam (EPS). Few studies mention hard plastic with a main component of microplastic, and we suggest new insights into the sources and pathway of microdebris into habitats.

Efectos del disturbio humano sobre la dinámica poblacional de Ocypode quadrata (Decapoda: Ocypodidae) en playas del Caribe mexicano / Effects of human disturbance on the population dynamics of Ocypode quadrata (Decapoda: Ocypodidae) in beaches of the Mexican Caribbean

Resumen:El cangrejo fantasma Ocypode quadrata, tiene una alta relevancia ecológica en las playas del Atlántico occidental y se ha propuesto como un indicador del impacto humano sobre este ecosistema. Sin embargo, no se han evaluado los efectos del disturbio humano sobre su dinámica poblacional. En este trabajo se compara la abundancia, el crecimiento y la mortalidad de O. quadrata en dos playas perturbadas (Aventuras y Majahual) y dos playas conservadas (Xcacel y Puerto Ángel) de las costas del Caribe mexicano. Se realizaron nueve muestreos en cada playa (marzo/2013-noviembre/2014). Durante las primeras horas de la noche se recolectaron cangrejos, de forma manual por tres personas, en un área aproximada de 9 000 m2. Los cangrejos fueron medidos, pesados y separados en tres grupos: jóvenes, hembras y machos. La mayor abundancia de cangrejos se encontró en las playas conservadas pero solo se observaron diferencias significativas entre Puerto Ángel y Majahual (Tukey, p<0.05). La proporción jóvenes- adultos fue 1:1 en Xcacel y Aventuras. En Majahual se recolectó un mayor número de jóvenes que adultos y en Puerto Ángel el número de adultos triplicó el de jóvenes. La talla máxima para Aventuras, Xcacel, Majahual y Puerto Ángel fue de 27, 32, 25 y 30 mm, respectivamente. En las playas se encontraron entre dos y tres grupos de edades diferentes. En las cuatro playas se recolectaron individuos con tallas menores de 10 mm en casi todos los meses de muestreo, indicando que el reclutamiento es continuo durante todo el año. La relación entre la longitud y el peso del cangrejo fantasma fue isométrica en las playas mejor conservadas y alométrica negativa en las playas impactadas. Los cangrejos de Puerto Ángel mostraron mejor condición corporal que en el resto de las playas (Tukey, p<0.05). Los valores de K oscilaron entre 0.6-0.97/año y la L∞ entre 29.0-33.6 mm. Los cangrejos en las dos playas conservadas mostraron mayores parámetros de crecimiento en comparación con las dos playas perturbadas. Los mayores valores de mortalidad se encontraron en Xcacel y Aventuras. En las playas perturbadas, la destrucción de las dunas, la limpieza mecánica y la remoción de materia orgánica, parecen ser las principales causas que conllevan a una baja abundancia de cangrejos, un menor crecimiento y una alta mortalidad. Sin embargo en las playas mejor conservadas, las relaciones biológicas parecen ser más importantes en regular la dinámica poblacional de esta especie. Estos resultados tienen relevancia desde el punto de vista de manejo de las playas arenosas, ya que el cangrejo fantasma es un buen indicador del disturbio humano y sus respuestas poblacionales son medibles y comparables.

Abstract:The ghost crab Ocypode quadrata is a relevant species in the Western Atlantic beaches, and has been proposed as an indicator of human impact in these ecosystems. Eventhough some studies have covered various aspects of its natural history, no evaluations on the effects of human disturbance on its population dynamics have been made. This work compared the abundance, growth, and mortality of O. quadrata in two disturbed beaches (Aventuras and Majahual) and two preserved beaches (Xcacel and Puerto Angel) from the Mexican Caribbean. For this, nine samplings were made on each beach (every two to three months) between March 2013 and November 2014. Crabs were collected manually by three people, during the night first hours and for one hour, and a total area of 9 000 m2 per beach. The crabs were measured, weighed, and separated into three groups: juvenile, male and female; while abundance was estimated by the number of collected crabs, and growth parameters were estimated using length frequencies. A total of 1 047 crabs were sampled in the four beaches; a higher crab abundance was found in the preserved beaches, but significant differences were only found between Puerto Angel and Majahual (Tukey, p<0.05). The adult- juvenile ratio was 1:1 in Xcacel and Aventuras, while in Majahual, more juveniles than adults were collected; and Puerto Angel had more adults than the juveniles. The size structure at Xcacel ranged from 4-32 mm, but in the rest of the beaches the minimum size was 5 mm. The maximum size at Aventuras, Majahual and Puerto Angel were 27 mm, 25 mm and 30 mm, respectively. The modal progression analysis of length's pooled data, revealed the presence of at least two groups of ages in all beaches. For all beaches, individuals smaller than 10 mm length were collected in almost all sampling months, indicating a continuous recruitment throughout the year. The length-weight relationship of the ghost crab was found isometric in the two preserved beaches, and negative allometric at the two impacted beaches. Crabs from Puerto Angel showed the highest body condition (Tukey, p<0.05). K-values ranged from 0.6-0.97/year and L∞ from 29.0 mm to 33.6 mm with higher values for the two preserved beaches. The highest mortality values were found in Xcacel and Aventuras. In the disturbed beaches, the destruction of the dunes, the mechanical cleaning and the removal of organic matter, seem to be the main causes that lead to a low abundance of crabs, their slower growth and higher mortalities. However, in the best preserved beaches, biological interactions appear to be the most important aspects in regulating the population dynamics of this species. These results supported the information that the ghost crab is a good indicator of human disturbance, and its population changes were clearly measurable and comparable among protected and impacted beaches; these results are also relevant for the management of sandy beaches in the Mexican Caribbean. Rev. Biol. Trop. 64 (4): 1625-1641. Epub 2016 December 01.

Taxonomy, morphology and distribution of Cymatosiraceae (Bacillariophyceae) in the littorals of Santa Catarina and Rio Grande do Sul / Taxonomia, morfologia e distribuição de Cymatosiraceae (Bacillariophyceae) nos litorais de Santa Catarina e Rio Grande do Sul

Species of Cymatosiraceae (diatoms) studied from Santa Catarina and Rio Grande do Sul littorals: Campylosira cymbelliformis, Cymatosira belgica, Cymatosirella minutissima, Plagiogrammopsis minima and Plagiogrammopsis vanheurckii) are presented with a morphological description, dimension data, distribution in the studied area and are illustrated in light microscope, and scanning and transmission electron microscopes. Superficial sand samples from the swash zone and plankton were collected from over 30 marine sandy beaches. Cymatosirella minutissima and Plagiogrammopsis minima are new recordings in Brazil widening their distribution to South America, previously being restricted to Europe. Campylosira cymbelliformis was the species most often observed in plankton samples and Plagiogrammopsis minima in sediment samples. Cymatosira belgica and Plagiogrammopsis minima were recorded as abundant species in Mariscal, Quatro Ilhas and Zimbros reaching a relative frequency of 9.6%. The study adds new morphological data to some taxa as the presence of rimoportula on C. minutissima and one row of poroids on copulae of P. minima, these features being in agreement with Cymatosiraceae diagnosis.

As espécies de Cymatosiraceae (diatomácea) encontradas no litoral de Santa Catarina e Rio Grande do Sul: Cymatosira belgica, Campylosira cymbelliformis, Cymatosirella minutissima, Plagiogrammopsis minima e Plagiogrammopsis vanheurckii são apresentadas com descrições morfológicas acompanhadas de dados referentes a dimensões, distribuição na área de estudo e ilustrações em microscopia óptica, e eletrônica de varredura e de transmissão. As amostras da areia superficial foram coletadas na região de varrido das ondas e de plâncton em mais de 30 praias arenosas. Cymatosirella minutissima and Plagiogrammopsis minima são registros novos para o Brasil ampliando sua distribuição para a América do Sul antes restritas à Europe. Campylosira cymbelliformis foi a espécies mais frequentemente observada nas amostras de plâncton and Plagiogramma minima in the sediment samples. Cymatosira belgica e Plagiogrammopsis minima são registradas como espécies abundantes em Mariscal, Quatro Ilhas e Zimbros alcançando a freqüência relativa máxima de 9,6%. Este estudo adiciona novos dados morfológicos para alguns táxons com a presença de uma rimopórtula em C. minutissima e uma fileira de poróides nas cópulas de P. minima, estando estas características de acordo com a diagnose da Cymatosiraceae.

Growth and production of Donax striatus(Bivalvia: Donacidae) from Las Balsas beach, Gibara, Cuba / Crecimiento y producción de Donax striatus (Bival-via: Donacidae) en playa Las Balsas, Gibara, Cuba

Abstract:Clams of the genus Donaxare worldwide the dominating group of the invertebrate community on sandy beaches. They are primary consumers that provide a significant abundance and biomass to the ecosystem. In the Caribbean, Donax striatushas an important role for nature and human, nonetheless studies on the population dynamics of this beach clam are scarce and no information exists on secondary production of this species. Growth parameters and secondary production of D. striatuswere estimated from February 2008 to November 2009 at Las Balsas beach, Northeastern Cuba, in order to provide basic information for management purposes. In each month 45 samples were taken by means of a PVC corer of 0.025 m2 area and sieved with a 1 mm mesh. Animals were measured and weighted with and without shell. A total of 5 471 specimens were collected during the sampling period. Shell length ranged from 2.7-33.3 mm. Growth parameters estimated from length frequency data were Lm = 36.1 mm, K= 0.8/yr and t0 = 0.2/yr. The growth performance resulted in values of 0'= 3.02. Life span was 2.4 yrs and mortality rate was 3.07 /yr. In 2008, mean abundance of D. striatusranged between 17.1770.7 ind./m2. In 2009 the lowest mean abundance was 34.4 and the highest was 892.5 ind./m2. During 2009 biomass and production was more than twice higher in comparison with 2008. Individual production showed highest values in the 24 mm shell size (3.74 g/m2.yr) and 25 mm (0.71 g/m2.yr), considering mass with shell and without shell, respectively. During 2009 abundance of individuals with 15 mm shell length or more increased resulting in higher biomass and production, compared to 2008. Using the conversion factor of wet mass to ash free dry mass (AFDM), annual production ranged between 2.87-6.11 g AFDM/m2.yr, resulting in a turnover rate (P/B) between 5.11 and 3.47 in 2008 and 2009, respectively. The rapid growth and high turnover rate of D. striatussuggest a rapid recovery of the population. These results support the idea that this beach clam is an important resource at Las Balsas beach. Thus its exploitation must continue with caution, and only at the level of a recreational fishery.

Resumen:Los estudios sobre la dinámica poblacional de la almeja de playa Donax striatusson escasos y no existe información sobre la producción secundaria de alguna población de esta especie. Los parámetros del crecimiento y la producción secundaria de D. striatusfueron estimados a partir de datos de muestreo obtenidos entre febrero 2008 y noviembre 2009 en playa Las Balsas en la zona norte oriental de Cuba para aportar información básica para su manejo. Cada mes se recolectaron 45 muestras usando un núcleo de PVC de 0.025 m2, el sedimento fue tamizado en malla de 1 mm. Los individuos recolectados fueron medidos y pesados con concha y sin concha. La longitud de la concha fue de 2.7-33.3 mm. Los parámetros de crecimiento estimados a partir de las frecuencias de tallas fueron: Lm= 36.1 mm, K= 0.8/año y t0 = 0.2/año. El índice de crecimiento fue de 0'= 3.02. El tiempo de vida estimado de 2.4 años y la mortalidad 3.07/año. En 2008 la abundancia media de D. striatusfluctuó entre de 17.1-770.7 ind/m2. En 2009 la menor abundancia fue de 34.4 y la mayor de 892.5 ind/ m2. En 2009 la biomasa y la producción fueron más del doble que las estimadas en 2008. La mayor producción somática individual fue aportada por individuos de 24 mm (3.74 g/m2.año) y 25 mm (0.71 g/m2.año), considerando la masa total con concha y sin concha respectivamente. Durante 2009 la abundancia de individuos de 15 mm de longitud o más, se incrementó resultando en mayor bio-masa y producción en comparación con 2008. Usando el factor de conversión de peso húmedo a peso seco libre de cenizas (PSLC), la producción anual en 2008 fue de 2.87 y en 2009 fue 6.11 g PSLC/m2.año, lo que resulta en una tasa de renovación (P/B) de 5.11 en 2008 y 3.47 en 2009. Estos resultados apoyan la idea que la almeja de playa es un recurso importante y su explotación debe continuar con cautela y solo a un nivel de una pesquería recreativa.

Dinámica poblacional de Donax denticulatus (Bivalvia: Donacidae) en playa Carenero, costa sur oriental de Cuba / Population dynamic of Donax denticulatus (Bivalvia: Donacidae) at Carenero Beach, Southeastern Cuba

Bivalve molluscs of Donax genus are a very important component of macro-invertebrate assemblages of sandy beaches, and some species are of commercial value in different countries. Although in Cuba Donax denticulatus is not a currently exploited species, the information concerning a stock assessment is a basic step for future use of this resource. With the aim to generate new data on this species structure, growth and secondary production, monthly samples of D. denticulatus were taken from a beach of the Southeastern coast of Cuba, from February to December 2008. Samples were taken from four stations located along the beach; three strata were marked (P1, P2 and P3) per station across the intertidal zone. Three replicated samples of sediments were taken from each stratum with a 0.025m2 PVC core and were posteriorly sieved with a 1mm mesh. Histograms of shell length were constructed based on 1mm intervals and growth parameters were estimated using ELEFAN I routine of FISAT. Mean density ranged from 146.67-855.55ind./m² and no differences were found among months (ANOVA, p>0.05) but among strata (Scheffé, p<0.05). An association of recruits, young and adults abundances with the strata (X², p<0.01) was found. Most of the recruits were found in the upper strata while young and adult individuals were abundant in the mid-lower strata. Size frequency histograms of this population showed recruitment between March-June. Growth parameters estimated by Von Bertalanffy were L∞=27.5mm and K=1.5/year; and the life spam was estimated in 1.5 years. Using the length-converted catch curve, the mortality rate (Z) was estimated in 4.97/year. Based in terms of Ash free dry mass (AFDM), mean biomass was estimated in 0.47g/m².year and the somatic production in 12.4g/m².year. The renewal rate (P/B) estimated for this population was 26.38, the highest among other Donax populations. High densities, fast growth and high somatic production indicate that this population can be exploited for fishing purposes for which some management measures are proposed.

Con el objetivo de aportar información sobre la estructura poblacional, crecimiento y producción secundaria de una población de D. denticulatus, se tomaron muestras mensuales desde febrero a diciembre 2008, en una playa de la costa sur oriental de Cuba. Las muestras se tomaron con un cilindro de PVC de 0.025m² en cuatro estaciones ubicadas a lo largo de la playa y en cada estación se delimitaron tres estratos (P1, P2 y P3) en la zona intermareal. No se encontró diferencias en la densidad entre los meses pero sí entre los estratos. Existe asociación en la abundancia de reclutas, jóvenes y adultos entre estratos. Existe un reclutamiento unimodal entre marzo y junio. Los parámetros de crecimiento fueron L∞=27.5mm y K=1.5/año. El tiempo de vida teórico fue de 1.5 años y la tasa de mortalidad (Z) se estimó en 4.97/año. En términos de peso seco libre de cenizas (PSLC) se estimó la biomasa media en 0.47g/m2.año y la producción somática en 12.4g/m².año, con una tasa de renovación (P/B) de 26.38. La evaluación de la población indica que esta tiene potencial para ser utilizada como carnada o para el consumo.

Composition and assemblage structure of demersal fish from São Cristóvão beach, Areia Branca, RN / Composição e estrutura da assembléia de peixes demersais da praia de São Cristóvão, Areia Branca, RN

Fish assemblages are an important element of sandy beaches, as they are fundamental for these ecosystems' balance of energy. Descriptions of the structure of fish assemblages in the sandy beaches of northeastern Brazil are scarce; this is especially true for the state of Rio Grande do Norte, which northern coast is poorly studied. This study aimed to identify the fish fauna of São Cristóvão Beach and to determine their assemblage structure. Three trawlings, considered as replicates, were undertaken monthly, in the same day, during 10 minutes each time, parallel to the coastal line, and in the direction of current, from February 2010 to January 2011. To describe the general pattern of the fish assemblage, the abundance, frequency and trophic categories of each species were estimated. On São Cristóvão Beach, 8894 individuals were captured, belonging to 58 species, 48 genera and 28 families. The most abundant and frequent species were Pomadasys corvinaeformis (Steindachner, 1868), Cathorops spixii (Agassiz, 1829), Stellifer rastrifer (Jordan, 1889), Pellona harroweri (Fowler, 1917), Stellifer stellifer (Bloch, 1790), Chirocentrodon bleekerianus (Poey, 1867), Larimus breviceps Cuvier, 1830, Menticirrhus americanus (Linnaeus, 1758)and Conodon nobilis (Linnaeus, 1758). The most abundant trophic category was first order carnivores. The ichthyofauna of São Cristóvão Beach is diversified and the most representative families match those observed in sandy beach ecosystems from other Brazilian regions. The results presented here reflect the basic knowledge necessary to conduct further research in the region.

As assembléias íctias são um elemento importante das praias arenosas, pois são fundamentais no balanço energético desses ecossistemas. Descrições da estrutura da assembléia de peixes de praias arenosas do nordeste brasileiro são escassas, em especial no estado do Rio Grande do Norte, cujo litoral norte é pobremente estudado. A presente pesquisa teve como objetivo inventariar a ictiofauna da praia de São Cristóvão, bem como conhecer a estrutura desta assembléia. Foram realizados três arrastos mensais com portas, com 10 minutos de duração cada (considerados como réplicas), paralelos à linha da costa, na direção da corrente, no período de fevereiro de 2010 a janeiro de 2011. Para descrever o padrão geral da comunidade de peixes, foram calculadas as abundâncias, frequências e os hábitos alimentares das espécies. Na praia de São Cristóvão foram capturados 8.894 indivíduos, pertencentes a 58 espécies, 48 gêneros e 28 famílias. As espécies mais abundantes e frequentes foram Pomadasys corvinaeformis (Steindachner, 1868), Cathorops spixii (Agassiz, 1829), Stellifer rastrifer (Jordan, 1889), Pellona harroweri (Fowler, 1917), Stellifer stellifer (Bloch, 1790), Chirocentrodon bleekerianus (Poey, 1867), Larimus breviceps Cuvier, 1830, Menticirrhus americanus (Linnaeus, 1758) e Conodon nobilis (Linnaeus, 1758). Quanto às proporções das categorias tróficas das espécies, a predominante é carnívora de primeira ordem. A ictiofauna da praia de São Cristóvão pode ser considerada diversificada e as famílias mais representativas coincidem com aquelas observadas nos ecossistemas praiais de outras regiões brasileiras. Os resultados aqui apresentados refletem o conhecimento básico necessário para a realização de pesquisas futuras na região.

Lípidos en el anfípodo Talorchestia margaritae (Amphipoda: Talitridae) y su relación con la ecología de la especie

Lipids in the amphipod Talorchestia margaritae (Amphipoda: Talitridae) and its relationship with the ecology of the species. T. margaritae, an endemic species inhabiting Venezuelan coasts, plays an important ecological role in plant and animal decomposition. To understand this issue in some animal groups, especially small ones, lipid composition analysis has been an interesting tool to describe their trophic relationships and food preferences. In order to assess this and visualize the components of their diet, we determined the lipid composition differences between males and females and among age classes in this species. Two sandy beaches were selected: Mangle Quemao and Las Mercedes de Paparo, from which sand samples of known volume were collected at the supralittoral area in 2007. Organisms were separated by age and sex classes, and their size, weight, density, biomass, total lipids (TL), lipid classes and fatty acid markers present in their tissues were determined. The sizes were similar for all age classes between the two locations, while the weights were higher for Mangle Quemao. The TL and lipid classes showed similar proportions between sexes, age classes and locations (TL: 3-5%; Phospholipids: 20-30%; Glycolipids: <1%; sterols: 4%). On the other hand, Triglycerides (TAG) were higher in Mangle Quemao, which may be related to the difference between the weights of two locations. The most abundant fatty acid biomarkers in the two studied sites were 16:0 and 18:1(n-9); this last one is characteristic of a carnivorous diet. The other nine markers were identified with changes in their distribution in organisms at Mangle Quemao and between males and females of both populations. Based on observed fatty acids markers we can assume T. margaritae as a generalist carnivore. Those populations were influenced by available food; inducing differences in weight, TAG proportion and markers diversity. Rev. Biol. Trop. 58 (3): 841-855. Epub 2010 September 01.

T. margaritae cumple un papel importante en la descomposición de restos vegetales y animales en las costas venezolanas. El objetivo fue determinar las diferencias en la composición lipídica entre sexos y talla de la especie. Para esto, especímenes de T. margaritae fueron recolectados en la zona supralitoral de dos playas arenosas: Mangle Quemao y las Mercedes de Paparo. Posteriormente se separaron por talla y sexo determinándoles su peso, densidad, biomasa y perfil lipídico. Todas las categorías presentaron tallas similares entre localidades. Los pesos fueron superiores en los organismos de Mangle Quemao. Los lípidos totales presentaron proporciones similares entre sexos, talla y localidad (3-5%), al igual que los fosfololípidos (20-30%), glicolípidos (<1%) y esteroles (4%), exceptuando los triglicéridos (TAG), siendo estos superiores en Mangle Quemao. Esto último pudiendo estar relacionado con la diferencia de pesos entre localidades. Los ácidos grasos más abundantes en ambas localidades fueron 16:0 y 18:1(n-9). Se identificaron otros 9 marcadores con variaciones en su distribución. Con base en los biomarcadores se puede catalogar a T. margaritae como una especie carnívora- generalista, siendo sus poblaciones influenciadas por la disponibilidad de alimento que a su vez, podría inducir diferencias de peso, TAG y biomarcadores.

O uso de praias arenosas com diferentes concentrações humanas por espécies de aves limícolas (Charadriidae e Scolopacidae) neárticas no sudeste do Brasil / The use of sandy beaches with different concentration of humans by Nearctic shorebirds (Charadriidae and Scolopacidae) in southeastern Brazil

As aves migratórias podem reconhecer humanos e animais domésticos como possíveis predadores, alterando seus padrões de abundância e comportamento de formação de bandos. O objetivo do presente estudo foi comparar a abundância de aves migratórias neárticas, a freqüência de bandos e o número médio de aves por bando em áreas com alta e baixa concentração humana em uma região costeira de praia arenosa no sudeste do Brasil. As aves, pessoas e cães foram contados mensalmente entre novembro de 2006 a abril de 2007. Foram registradas seis espécies de aves (Arenaria interpres, Calidris alba, Calidris canutus, Calidris pusilla, Charadrius semipalmatus, Pluvialis dominica) nas duas áreas, no entanto somente C. canutus foi registrado exclusivamente na área com baixa concentração humana. Houve diferença significativa no número médio de pessoas e cães entre as áreas, mas não no número médio de aves. Não houve correlação entre o número de humanos e aves, e entre cães e aves. Adicionalmente, não houve diferença significativa na freqüência de bandos e número de indivíduos por bando entre as áreas. Os resultados deste estudo destacaram a sensibilidade de C. canutus na área com alta concentração humana e a necessidade de futuras investigações que determinem os limites máximos de concentração de pessoas e cães domésticos que as aves migratórias neárticas podem tolerar para a tomada de ações de proteção em áreas costeiras com ocupação humana.

Migratory birds may recognize humans and domestic animals as potential predators. Thus, their abundance and behavior in flock formation may change in areas with high human concentration. This study compared the abundance of Nearctic migratory birds, the frequency of their flocks and the average number of birds per flock at high and low human concentration areas in a coastal region in southeastern Brazil. Birds, humans and domestic dogs were counted monthly between November 2006 and April 2007. Six bird species (Ruddy Turnstone Arenaria interpres, Sanderling Calidris alba, Red Knot Calidris canutus, Semipalmated Sandpiper Calidris pusilla, Semipalmated Plover Charadrius semipalmatus, and American Golden-Plover Pluvialis dominica) were recorded. Only Red Knot were restricted to the low human concentration area. The average number of humans and domestic dogs differed between areas with different levels of disturbance, whereas no difference on the average number of birds was detected. There were no correlation between number of humans and birds, nor between domestic dogs and birds. Additionally, the frequency of flocks and average number of birds per flock did not vary significantly between the areas. These results highlighted the sensibility of Red Knot in the high human concentration area as well as the need to find out, in future investigations, the maximum concentration of people and domestic dogs that birds can tolerate in human occupied areas to employ conservation efforts in preserving Nearctic shorebirds.

The birds at Ilha Comprida beach (São Paulo State, Brazil): a multivariate approach / Aves da praia da Ilha Comprida (Estado de São Paulo, Brasil): uma análise multivariada

Birds were censused weekly from January 1999 to January 2001 along Ilha Comprida beach, a barrier island off São Paulo, southeastern Brazil. To evaluate the similarity in the bird's species composition among the weekly surveys, species counts data were arranged on a data matrix with 144 weekly surveys, analyzed following a multivariate analysis protocol. We counted a total of 205,399 individuals and 52 species. Migratory birds were an important component of the avifauna (maximum N = 21,294 individuals and 14 species). The largest numbers of birds were observed during summer, when Nearctic migrants arrive. All 14 of the most common species were migrants, including Calidris alba, Sterna maxima, Charadrius semipalmatus, Sterna hirundo, Thalasseus maximus, Pluvialis dominica and Calidris fuscicollis. The most common residents were Thalasseus s. eurrygnathus, Larus dominicanus, Coragyps atratus, Fregata magnificens and Sterna hirundinacea. Recently, most of the peripheral area adjacent to the beach has been urbanized and rapid habitat change is progressing. In this paper, we establish a reference that will allow future comparisons to assess the impact of such urbanization on the composition of bird populations on Ilha Comprida.

As aves foram contadas semanalmente de janeiro 1999 a janeiro 2001 ao longo da praia de Ilha Comprida, sendo esta, uma ilha de barreira localizada ao sul do estado de São Paulo. Para se avaliar a similaridade da composição das aves, os dados das espécies foram arranjados numa matrix com 144 amostras semanais, estudados seguindo um protocolo de análise multivariada. Contou-se um total de 205.399 indivíduos de 52 espécies diferentes. As aves migratórias foram um componente importante da avifauna na ilha (máximo N = 21.294 indivíduos e 14 espécies). O maior número de aves foram observadas durante o verão, quando as migrantes nearticas chegaram. Dentre as 14 espécie migrantes identificadas as mais comuns foram: Calidris alba, Thalasseus maximus, Charadrius semipalmatus, Sterna hirundo, Pluvialis dominica and Calidris fuscicollis. Já as espécies residentes mais comuns foram: Thalasseus s. eurrygnathus, Larus dominicanus, Coragyps atratus, Fregata magnificens and Sterna hirundinacea Recentemente, a maior parte das áreas periféricas junto à praia estão sendo urbanizadas provocando mudanças rápidas do habitat. Neste trabalho, nós pretendemos estabelecer uma referência que permita futuras comparações, para se poder avaliar o impacto da urbanização na composição das populações das aves que são encontradas na praia da Comprida.

Seminavis atlantica Garcia, a new psammic diatom (Bacillariophyceae) from southern Brazilian sandy beaches

The paper presents the description of Seminavis atlantica Garcia, a psammic marine diatom from dissipative sandy beaches from southern Brazil. It is characterized by its convex linear dorsal margin (37 to 50 percent of its length is in a straight line), linear ventral margin and raphe located very close to the ventral margin. Its morphology is compared to similar species such as Amphora clevei Grunow, Amphora angusta (Greg.) Cleve var. orientalis Allem, Amphora ventricosa Gregory and Amphora eulesteinii Grunow.

O trabalho apresenta a descrição de Seminavis atlantica Garcia, uma diatomácea psâmica marinha de praias arenosas dissipativas do Sul do Brasil. Esta é caracterizada por sua margem dorsal linear (37 a 50 por cento do seu comprimento apresenta-se em linha reta), margem ventral linear, e rafe localizada muito próxima da margem ventral. Sua morfologia é comparada a espécies similares como Amphora clevei Grunow, Amphora angusta (Greg.) Cleve var. orientalis Allem, Amphora ventricosa Gregory, e Amphora eulesteinii Grunow.

Population dynamics of Excirolana armata (Isopoda: Cirolanidae) in Buenos Aires beaches, Argentina

Se estudió la dinámica y estructura poblacional de Excirolana armata en tres playas arenosas de la provincia de Buenos Aires (Argentina), de enero de 2004 a marzo de 2005. Se seleccionaron playas sometidas a distintos tipos de influencias antropogénicas. Los parámetros de la función de crecimiento de von Bertalanffy fueron determinados en cada playa. Esta especie mostró una notable fluctuación en su crecimiento, con tasas más bajas a fines de otoño y en invierno. La población de la playa con mayor grado de erosión antropogénica presentó los valores menores y más estables de densidad y biomasa, la más alta tasa de mortalidad y la menor longevidad. Las variaciones temporales del coeficiente alométrico de la relación longitud-peso seco indicaron un patron cíclico, con los menores valores en otoño-invierno y los mayores en verano. Las hembras predominaron en la población ebido a la corta duración de la temporada reproductiva. Las poblaciones argentinas y uruguayas tienen índices similares en el crecimiento, pero difieren en los valores de abundancia y densidad, probablemente como respuesta a variaciones en la orfodinámica de las playas y en las interacciones biológicas.

The population dynamics and structure of the cirolanid isopod Excirolana armata were studied from January 2004 through March 2005 in three sandy beaches of Buenos Aires Province (Argentina). Beaches with different types of anthropogenic influences were selected. The von Bertalanffy’s growth function parameters were determined for each population. There was a marked fluctuation in growth, with lowest rates in late autumn and winter. The isopod population of the beach exposed to the highest degree of anthropogenic erosion had thelowest and most stable values of abundance and biomass, the highest mortality rate and the shortest life span.Temporal fluctuations of the allometric coefficient of the length‑dry weight relationship indicated a cycling pattern,with lowest values during the autumn‑winter period and peak values in the summer. Females predominatedin the populations due to the short duration of the reproductive season. Argentine and Uruguayan populationsshowed similar growth performance indices, but differed in their abundance and biomass values, probably asa response to variations in beach morphodynamics and biological interactions.