Impacts of Anthropogenic Stressors on Hydrochemistry, Benthic Macroinvertebrates and Sediment Characteristics of the Lagos Lagoon, Nigeria

The anthropogenic impact on the water, benthic macroinvertebrates and sediment grain size of Lagos lagoon was investigated between July and October, 2019. Ten sampling stations were selected based on their importance as likely sources of different forms of anthropogenic stressor to the lagoon. Water temperatures, pH and salinity were measured in situ. Water and benthic samples were collected monthly and analysed using standard methods. Nutrient levels were determined using a spectrophotometer. The hydrochemistry of the stations differed significantly (p<0.05) with the exception of temperature and pH. The sediment grains across the study stations consists basically of sand and mud, with sand dominating the grain type. A total of 502 individuals comprising 3 phyla, 4 classes, 10 families and 11 species was recorded. The phylum mollusca which contributed 92% to the total number of individuals was represented by two Classes; Gastropoda and Bivalvia, with the gastropod Tympanotonus fuscatus having the highest number of individuals (321). Thephylum Annelida represented by one Class, Polychaeta and two Species Nereis sp. and Capitella capitata contributed 6% to the total number of individuals. The class Crustacea, representing the Phylum Arthropoda was the least sampled (7 individuals) constituting about 1.4% of the total population Result showed that different pollution sources have negatively impacted the water chemistry of the lagoon and reduced the diversity and abundance of its benthic macroinvertebrates community. The sedentary nature of this group of benthic fauna could be the major reason why they are most impacted.

Towards Conservation of Coastal Wetlands: An Assessment of The Ecological Health Status of A Neglected Lagoon In Ghana

Coastal wetlands are important ecosystems that support biological communities and human populations. Anthropogenic activities have over the years affected these coastal wetlands globally leading to a loss of about 50% of these areas. There have therefore been calls to conserve these wetlands in order to sustain future generations. However, data to support conservation efforts on most of these ecosystems is lacking. The ecological health status of an aquatic system is one indicator that can form the basis of conservation or restoration actions. In Ghana, the Brenu Lagoon in the Central Region has been neglected in terms of ecological health research over the years. This study therefore aimed at assessing the ecological health of the Brenu lagoon using benthic macroinvertebrates. The study showed that the lagoon is hypersaline and moderately polluted with a dominance of two stress-tolerant species – Capitella Capitata and Ampithoe sp. The current state of pollution of the lagoon may be associated with waste disposal and agricultural activities within the catchment of the lagoon. Further studies are required to establish the linkage between these activities and the state of the lagoon on the basis of which remedial actions can be taken.

Efecto de la temperatura y salinidad en la mortalidad de adultos de Capitella sp. (Polychaeta: Capitellidae) en el laboratorio

Introducción: El poliqueto marino y estuarino Capitella capitata es una especie endobentónica y considerado cosmopolita. El cultivo en el laboratorio de este complejo de especies permite su utilización como especie para pruebas en bioensayos de toxicidad, así como para estudios de reproducción. Objetivo: El presente trabajo pretende observar la mortalidad en dos rangos de temperatura y salinidad como condiciones óptimas para cultivar Capitella sp. en el laboratorio. Metodología: La recolección de especímenes se realizó en la provincia de Callao, Perú en noviembre de 2016 y enero de 2017. Se realizó un bioensayo para observar la mortalidad bajo diferentes intervalos de temperatura y salinidad: tratamiento 1 con los organismos recolectados en enero y con intervalos de temperatura (20-22° C) y salinidad (30-32 ups) similares a los registrados en el campo; tratamiento 2, con los organismos recolectados en noviembre y con intervalos de temperatura (24-26 °C) y salinidad (32 a 34 ups) seleccionados de acuerdo con datos de la bibliografía. Resultados: El aumento de la temperatura y el tiempo influyeron significativamente en la mortalidad de los organismos de ambos tratamientos (Correlación de Spearman), mientras que la salinidad y el oxígeno no presentaron correlación significativa con la mortalidad. Se observó efecto significativo del tiempo en la mortalidad, con más muertes a partir de la segunda mitad del experimento. Los organismos del tratamiento 1, con condiciones ambientales similares a las de su hábitat sobrevivieron más que los del tratamiento 2. Estos resultados también se observaron en la variabilidad porcentual en el coeficiente de variación entre los días por tratamiento. No se observaron diferencias entre los tratamientos al comparar las curvas acumuladas de mortalidad. Conclusión: Los intervalos óptimos para el cultivo en el laboratorio de Capitella sp. son los de su hábitat. Las posibles causas de la mortalidad observada se atribuyen, además de la temperatura y el tiempo, a la edad, estado de salud o de madurez de los organismos y, probablemente, la mala calidad del agua utilizada en el bioensayo.

Patterns of polychaete communities in relation to environmental perturbations in a subtropical wetland of Hong Kong

Benthic polychaetes in the largest intertidal mudflat of Hong Kong were analysed for potentially stressed environmental conditions from pollution. Over a two-year period, a total of 14 species were recorded with the species diversity (H′(log2)) ranged from 0.54 to 2.4. The community was dominated by two large polychaetes (Neanthes glandicincta and Potamilla acuminata) and a number of small pollution tolerant species (Tharyx, Capitella capitata and Prionospio cirrifera). It was also characterized by both temporal and spatial variations in terms of abundance and species composition with the lowest species number observed at onshore Station B in August and the highest at offshore Station D in February. Two distinct polychaete communities were formed along the intertidal towards subtidal mudflat, particularly the assemblage at onshore Station B showing a significant difference from those at the other three stations (P < 0.05, N = 32). Results of the abundance–biomass comparison (ABC) indicated a typical impacted community at the whole study area, especially at Station B which was close to the Shenzhen River mouth and mangrove forest. The total organic carbon had a significant positive effect on the abundance of Capitella capitata (P = 0.037, N = 8) while sedimentary compositions were statistically related to the abundance of Potamilla acuminata, Tharyx and total abundance of polychaetes (P < 0.05, N = 8). In conclusion, both the polluted Shenzhen River and nearby mangrove may be responsible for the decline in species richness and diversity as well as changes in community structure. Polychaetes can be used as the appropriate indicators in habitat ecological condition assessment instead of the whole benthic community.

Morphometric analysis of Capitella capitata (Polychaeta, Capitellidae)

Accurate size measurements are fundamental in characterizing the population structure and secondary production of a species. The purpose of this study was to determine the best morphometric parameter to estimate the size of individuals of Capitella capitata (Fabricius, 1780). The morphometric analysis was applied to individuals collected in the intertidal zones of two beaches on the northern coast of the state of São Paulo, Brazil: São Francisco and Araçá. The following measurements were taken: the width and length (height) of the 4th, 5th and 7th setigers, and the length of the thoracic region (first nine setigers). The area and volume of these setigers were calculated and a linear regression analysis was applied to the data. The data were log-transformed to fit the allometric equation y = ax b into a straight line (log y = log a + b * log x). The measurements which best correlated with the thoracic length in individuals from both beaches were the length of setiger 5 (r² = 0.722; p<0.05 in São Francisco and r² = 0.795; p<0.05 in Araçá) and the area of setiger 7 (r² = 0.705; p<0.05 in São Francisco and r² = 0.634; p<0.05 in Araçá). According to these analyses, the length of setiger 5 and/or the area of setiger 7 are the best parameters to evaluate the growth of individuals of C. capitata.

Redescription of Capitella capitata (Fabricius) from West Greenland and designation of a neotype (Polychaeta, Capitellidae)

Capitella capitata (Fabricius, 1780), the type species of the genus, was originally described from the SW coast of Greenland; however, current definitions of the species are largely based on Eisig (1887), who described specimens from Naples on the Mediterranean coast. Eisig’s excellent account of the morphology of a sexually dimorphic species has subsequently been applied to specimens collected from worldwide locations. C. capitata was considered cosmopolitan in its distribution until J.P. Grassle and others identified numerous sibling species in laboratory culture. A large collection of Capitella from locations along the W, SW, and SE coasts of Greenland was provided by the Zoological Museum, University of Copenhagen (ZMUC). The collections included about 680 specimens with distinctive prostomial, thoracic, and setal morphology that differs from the typical depiction of the species in most faunal accounts. A neotype was selected from an excellent collection of approximately 250 specimens from Mârmorilik on the Affarlikassâ Fjord on the inner Uummannaq Fjord system, north of Disko Bay. All available collections from the ZMUC are believed to belong to the same species, which is here considered to be Arctic and subarctic in distribution. Additional material from the Alaskan Arctic supports this hypothesis. The Greenland species has a short, cup-shaped, wider-than-long prostomium joined to a narrow peristomial ring that is retracted slightly into setiger 1. In most specimens, the first four thoracic setigers gradually increase in size, with setiger 4 being the largest thoracic segment, and then decrease over the next five setigers, with setiger 9 being smaller than subsequent anterior abdominal segments. The thoracic region is thus markedly distinct visually from the abdominal region. Setigers 8–9 typically lack fascicles of notosetae, but 80% of the specimens examined have genital spines and most have copulatory organs that are secretory in nature: they contain numerous small secretion granules but no sperm. Many of these specimens have eggs and larvae within their tubes, suggesting functional hermaphroditism. The present redescription of C. capitata serves to establish a baseline against which the many known but undescribed species can be compared. Previous accounts of C. capitata based on the Eisig concept and largely from boreal and temperate localities should be reevaluated.

Macrobenthic community structure and distribution in the Zwin nature reserve (Belgium and The Netherlands)

Distribution and structure of intertidal macrobenthic communities in the Zwin nature reserve, a lagoonal inlet consisting of marsh and tidal flat habitats, was investigated using univariate and multivariate analyses. Macrobenthos community structure was related to environmental characteristics and discussed in the framework of the implemented extension of the nature reserve.Based on explorative multivariate techniques, five different sample groups (SGs) were distinguished, which were, in general, located in different habitats of the Zwin nature reserve. The ecologically most important SGs consisted of the highest macrobenthic density, diversity and highest densities of Nereis diversicolor and Scrobicularia plana; these important prey species for wading birds and fish occurred in the deep tidal inlet channels. This habitat was characterized by fine to medium sand sediment and strong tidal currents, guaranteeing water renewal at each high tide. Other SGs were found in less and erratically submersed and thus stressed areas (i.e. tidal pond, salt pans and shallow flats). These assemblages were characterized by typical r-strategists (i.e. Capitella capitata and Polydora cornuta) and typical supralittoral, mobile species (i.e. Orchestia gammarellus and Collembola spp.). Being ecologically most important, the extension of wide, tidal creeks should be a prime target within the future development and management of the nature reserve.