Quantifying Marine Plastic Debris in a Beach Environment Using Spectral Analysis

Marine plastic debris (MPD) is a globally relevant environmental challenge, with an estimated 8 million tons of synthetic debris entering the marine environment each year. Plastic has been found in all parts of the marine environment, including the surface layers of the ocean, within the water column, in coastal waters, on the benthic layer and on beaches. While research on detecting MPD using remote sensing is increasing, most of it focuses on detecting floating debris in open waters, rather than detecting MPD on beaches. However, beaches present challenges that are unique from other parts of the marine environment. In order to better understand the spectral properties of beached MPD, we present the SWIR reflectance of weathered MPD and virgin plastics over a sandy substrate. We conducted spectral feature analysis on the different plastic groups to better understand the impact that polymers have on our ability to detect synthetic debris at sub-pixel surface covers that occur on beaches. Our results show that the minimum surface cover required to detect MPD on a sandy surface varies between 2–8% for different polymer types. Furthermore, plastic composition affects the magnitude of spectral absorption. This suggests that variation in both surface cover and polymer type will inform the efficacy of beach litter detection methods.

Marbled Murrelets prefer stratified waters close to freshwater inputs in Haida Gwaii, British Columbia, Canada

The Marbled Murrelet (Brachyramphus marmoratus) is a small seabird that is currently listed as threatened in Canada. Understanding this species’ marine habitat preferences plays a vital role in our ability to focus conservation planning. We used the longest-running at-sea survey dataset available in British Columbia to examine hotspot persistence and habitat use at Laskeek Bay, Haida Gwaii, BC. The Laskeek Bay Conservation Society has been conducting spring and summer surveys along fixed transect routes in open and shoreline waters from 1997 to 2018. Along with analyzing this long-term dataset, we conducted surveys to measure oceanographic variables (2018–2019) and tested whether Marbled Murrelets in the same area used prey and oceanographic information to select marine habitat in conjunction with physical habitat features. Our hotspot persistence map, defined as areas that repeatedly had counts above a 75% threshold relative to other areas during a given survey, showed that murrelets consistently preferred shoreline transects. Murrelets also preferred shallow marine areas closer to streams, above higher proportions of sandy substrate and closer proximity to abundant nesting habitat. Modeling weather and time variables contributed little additional predictive power. Nonetheless, models that included physical environmental, oceanographic, and prey variables outperformed those with only physical environmental variables. Stratified water was the oceanographic variable most strongly related to higher counts. Our study suggests that stratified waters could work with stream systems to create productive zones for foraging murrelets, and highlights the importance of murrelets having access to marine areas with the preferred physical features.

Bioturbation by black soldier fly larvae—Rapid soil formation with burial of ceramic artifacts

Bioturbation involves the incorporation of residues from the surface soil into the subsoil; however, common small soil ‘bioengineers’, such as earthworms or termites, are unlikely to transport human artifacts to deeper soil horizons. However, such artifacts occur in the deeper soil horizons within Amazonian Anthrosols (Terra Preta). Here we test the assumption that such tasks could be carried out by fly larvae, which could thus play a crucial role in waste decomposition and associated soil mixing under tropical conditions. We performed two greenhouse experiments with sandy substrate covered with layers of organic waste, ceramic fragments, and black soldier fly larvae (BSFL) (Hermetia illucens (L.) (Dipt.: Stratiomyidae)). We used in-situ images to assess the rate of bioturbation by BSFL, and then designed our main study to observe waste dissipation (reduction of organic carbon and phosphorus contents from waste model trials with and without charcoal) as related to larval-induced changes in soil properties. We found that the bioturbation of macroinvertebrates like BSFL was able to bury even large (> 5 cm) ceramic fragments within hours, which coincided with high soil growth rates (0.5 cm h-1). The sandy soil was subsequently heavily enriched with organic matter and phosphorus originating from organic waste. We conclude that BSFL, and possibly other fly species, are important, previously overlooked soil ‘bioengineers’, which may even contribute to the burial of artifacts in Anthrosols and other terrestrial waste dumps.

Conservation of the endangered blue land crab Cardisoma guanhumi Latreille in Latreille, Le Peletier, Serville & Guérin, 1828 (Decapoda: Brachyura: Gecarcinidae) in Brazil: optimal habitats and environmental factors

Cardisoma guanhumi Latreille in Latreille, Le Peletier, Serville & Guérin, 1828, the blue land crab, is a marine semi-terrestrial crab that builds burrows in different habitats along estuaries, an ecosystem severely modified and fundamental to this endangered species in Brazil. The presence of adequate habitats and physical, chemical, and biological conditions often determine the spatial distribution of populations. We aimed to characterize the most relevant environmental conditions among the main environments present in southern Bahia state, Brazil, and evaluate their influence on the spatial distributions of C. guanhumi to define which habitats are most critical for the conservation of the species. Our results showed that there is no relationship between spatial distributions and any particular habitat, but instead to the physical and other environmental parameters studied. Low-elevation areas along the river shore, shading, a supply of leaf litter, and bare sandy substrate are highlighted as priority for the conservation of C. guanhumi. These physical factors limit the distribution of juveniles, which form dense groups on river shores without significant differences between habitats. The preservation of the native forest and restinga shrubs that border rivers appear as fundamental for the conservation of the species.

STRUKTUR KOMUNITAS MAKROALGA DI PANTAI GEGER DAN PANTAI MENGENING KABUPATEN BADUNG

Macroalgae is a type of flora known as seaweed and is classified into low-level plants, where roots, stems, and leaves are relatively difficult to distinguish. This study aims to determine the differences of habitat characteristics, number of species, biomass, and macroalgae community structure in Geger Beach and Mengening Beach. This quadrant transect method was used to collect the data. The results show that Geger Beach has sandy substrate, while Mengening Beach has substrate consisting of coral rock. The water quality in both locations are still suitable for macroalgae growth. The results of the study found 8 types of macroalgae in Geger Beach and 10 types of macroalgae in Mengening Beach. The highest macroalgae biomass at Geger Beach was found in Gracilaria hayi with the weight ranging from 72.08-73.18 g/m2, while at Mengening Beach was found in the Valonia aegagropila, ranging from 181.31-190.40 g/m2. The diversity index of macroalgae in Geger Beach was between 1.93-1.99, while at Mengening Beach was between 1.79-2.07, therefore categorized as medium. The dominance index of macroalgae at Geger Beach was between 0.15-0.17, while at Mengening Beach was between 0.17-0.25, therefore the dominance index at both site was categorized low. The evenness index at Geger Beach was between 0.93-0.96, while at Mengening Beach was between 0.78-0.90, which categorized as stable conditions.

Trace fossils and palynomorphs in Holocene calcareous concretions from Lake Selbusjøen, Mid-Norway: Post-glacial environmental records

Trace fossils and palynomorphs are recorded for the first time in Holocene calcareous concretions from Lake Selbusjøen, Central Norway. The described trace fossils can be assigned to the Mermia ichnofacies, characterizing lake deposits with good oxygenation and low depositional energy. The predominance of simple grazing trails and shallow burrows (e.g. Cochlichnus, Helminthoidichnites and Treptichnus) in silty and sandy concretions possibly represent relatively low-energy sublittoral parts of the lake, while the occurrence of Vagorichnus and Arenicolites in sandy substrate points to littoral and shallow sublittoral areas with moderate depositional energy. The trace fossils and palynomorph assemblages from Lake Selbusjøen appear to relate to periods of climatic warming during Pre-Boreal times, and possibly also Atlantic times.

Explaining the Atlas Cedar (Cedrus atlantica M.) dieback by studying Water relations of young plants subject to an edaphic drought

Cedrus atlantica M. stands from the Middle Atlas Mountains in Morocco have been severely affected by dieback. The edaphic water deficit could be the cause that triggered this phenomenon leading to the mortality of dying trees. The objective of this work is to analyze the ecophysiological behavior of Atlas cedar seedlings subjected to an edaphic drought of progressive intensity. During the drying cycle, the relative moisture content of the substrate decreased significantly to reach 12.71% at the end of the test; 4.27% and 2.88% respectively for the basaltic, calcareous, and sandy substrate. The pre-dawn water potential reached very low values of -32.25, -37.38, and -39.50 bar at the end of the water drying cycle. The critical water potential varied between -36 and -39 bar depending on the type of substrate. The mean maximum stomatal conductance under favorable water conditions was of the order of 330 mmol/m2/s. It was reduced, due to drying, in proportion to the reduction in substrate moisture content. Atlas cedar maintains gas exchange under conditions of severe water stress but can be lethal with extreme and recurrent droughts. This behavior can explain the development of the phenomenon of cedar stand decline, which is more accentuated especially with adverse ecological conditions.

KARAKTERISTIK HABITAT DAN STRUKTUR POPULASI KERANG BAMBU (Solen lamarckii, Chenu 1984) DI ZONA INTERTIDAL DESA APIAPI KECAMATAN BANDAR LAKSAMANA KABUPATEN BENGKALIS

The study about habitat characteristics and population structure razor clam (Solen lamarckii, Chenu 1984) in intertidal zone Apiapi Village Bandar Laksamana District Bengkalis Regency conducted on January 2020. The purpose of this study was to analyze about habitat characteristics and population structure of razor clam and the correlation between substrate particle size and population density of razor clam. The habitat parameters measured include the physical and chemical parameters of sea waters. Determination of the station using purposive sampling method. Razor clam samples were collected by using a 1 x 1 m2 frame that laid along a transect. There were 4 plots and 3 subplots along the transect as replications. The result showed, the sediment tipe was sandy substrate, organic material was low, total suspended solid was high. Population density of razor clams was 3.3-23.3 Ind/m2. The distribution pattern of razor clams through each plot was uniform. While, the most common size of razor clam 5.04-5.62 cm. The correlation between particle size and population density of razor clam was strong.