Aquatic Decomposition Research Articles

The correlation between the Aquatic Decomposition Score (ADS) and the post-mortem submersion interval measured in Accumulated Degree Days (ADD) in bodies recovered from fresh water.

The Aquatic Decomposition Score (ADS) made by van Daalen et al., was developed to approximate the Post-Mortem Submersion Interval (PMSI) in bodies recovered in salt water. Since the decomposition process in salt water differs from the process in fresh water due to salinity, the temperature, and the depth of the water, we wanted to investigate whether there is a correlation between the ADS and the PMSI and if the ADS can be used to make an estimation of the PMSI in bodies recovered from fresh water. For the latter, the PMSI was measured using Accumulated Degree Days (ADD). In our study we included seventy-six human remains found outdoors in fresh water. Their decomposition was measured using the ADS. A strong correlation was found between the ADS and the PMSI. Also, it was found that the ADS can significantly estimate the ADD. Despite the more varied circumstances under which bodies in fresh water are found when compared to those found in salt water, the ADS can be used to measure the decomposition and accurately estimate the ADD, and thus the PMSI. More research is needed to validate our method and make a prediction model with smaller confidence intervals.

An Aquatic Decomposition Scoring Method to Potentially Predict the Postmortem Submersion Interval of Bodies Recovered from the North Sea.

This study aimed to develop an aquatic decomposition scoring (ADS) method and investigated the predictive value of this method in estimating the postmortem submersion interval (PMSI) of bodies recovered from the North Sea. This method, consisting of an ADS item list and a pictorial reference atlas, showed a high interobserver agreement (Krippendorff's alpha≥0.93) and hence proved to be valid. This scoring method was applied to data, collected from closed cases-cases in which the postmortal submersion interval (PMSI) was known-concerning bodies recovered from the North Sea from 1990 to 2013. Thirty-eight cases met the inclusion criteria and were scored by quantifying the observed total aquatic decomposition score (TADS). Statistical analysis demonstrated that TADS accurately predicts the PMSI (p<0.001), confirming that the decomposition process in the North Sea is strongly correlated to time.

Elevated atmospheric CO2 interacts with drought and competition to produce complex results in plant quality and subsequent microbial aquatic decomposition

Human activities enhance the atmospheric CO2 concentration and modify climatic patterns, which could change the growth and quality of plant materials, as well as their subsequent decomposition, thus altering stream ecosystem functioning. These effects could be modulated by interactions between plant species differing in biological traits and competitive capacity. We cultivated the forb Trifolium pratense and the grass Agrostis capillaris under different CO2 concentration (ambient or elevated), water availability (control or drought), and competition (monoculture or mixture). The material thus grown was conditioned in a stream for microbial colonization, and its subsequent decomposition was measured in laboratory microcosms. Elevated CO2 reduced the quality of T. pratense but not that of A. capillaris. Water shortage limited plant quality but did not interact with CO2 concentration. Interspecific competition only affected nitrogen concentration in A. capillaris. Elevated CO2 did not affect decomposition rate, and A. capillaris, the species richer in nutrients, decomposed more slowly. Our results showed that the decomposition rates of plant materials grown under elevated CO2 are difficult to predict due to species-specific responses and interactions with other factors.

Benthic community structure and ecosystem functions in above- and below-waterfall pools in Borneo

Waterfalls are geomorphic features that often partition streams into discrete zones. Our study examined aquatic communities, litter decomposition and periphyton growth rates for above- and below-waterfall pools in Ulu Temburong National Park, Brunei. We observed higher fish densities in below-waterfall pools (0.24 fish m−2 vs. 0.02 fish m−2 in above-waterfall pools) and higher shrimp abundance in above-waterfall pools (eight shrimp/pool vs. less than one shrimp/pool in below-waterfall pools). However, macroinvertebrate densities (excluding shrimp) were similar among both pool types. Ambient periphyton was higher in below-waterfall pools in 2013 (4.3 vs. 2.8 g m−2 in above-waterfall pools) and 2014 (4.8 vs. 3.4 g m−2 in above-waterfall pools), while periphyton growth rates varied from 0.05 to 0.26 g m−2 days−1 and were significantly higher in below-waterfall pools in 2014. Leaf litter decomposition rates (0.001 to 0.024 days−1) did not differ between pool types, suggesting that neither shrimp nor fish densities had consistent impacts on this ecosystem function. Regardless, this research demonstrates the varied effects of biotic and abiotic factors on community structure and ecosystem function. Our results have highlighted the importance of discontinuities, such as waterfalls, in tropical streams.

Reed litter Si content affects microbial community structure and the lipid composition of an invertebrate shredder during aquatic decomposition

• High Si concentration in reed leads to a decline of gram positive bacteria in biofilm. • High Si concentration in reed leads to a decline of gram negative bacteria in FPOM. • Basal decomposers were affected by the Si availability in plant resources. • Si changed the lipid composition in Gammarus pulex . The decomposition of plant litter is an important mechanism in regard to energy and nutrient dynamics of ecosystems. Silicon concentration of plant tissue can affect these processes by changing litter quality, i.e. nutrient stoichiometry and cellulose and phenols content. To determine which group of microbial decomposers benefits from high Si content in plants and how this impacts on animal decomposers, a batch experiment was conducted with reed leaf litter ( Phragmites australis ) differing in Si content in the presence/absence of invertebrate shredders ( Gammarus pulex ). Lipid concentration of G. pulex , in reed litter and fine particulate matter (FPOM) were examined. High Si concentration in reed resulted in a decline of gram positive bacteria in the heterotrophic biofilm and of gram negative bacteria in FPOM. The lipid composition in the next trophic level, the decomposer G. pulex , changed too, indicating a diet shift in favor of bacteria and algae with increasing litter Si concentration. Thus, basal decomposers were affected by the Si availability in plant resources, and these effects likely persist along the food chain, as FPOM is a dominant food supply for other groups, e.g. collectors. This impact of Si content on plant substrate quality for decomposer food webs may have global relevance, due to related modifications in carbon and nutrient cycling during litter decomposition.

Silicon in aquatic vegetation

Summary Silicon (Si) use by plants has not always received the research attention of other elements. Yet today, the importance of Si for plant functioning is slowly becoming better understood. Si is a crucial element for many terrestrial plant species (especially grasses), yet a recent surge of research has shown that some species of aquatic plants contain significant amounts of Si too. We argue that degree of Si accumulation is a functional trait in aquatic vegetation, with plants adapting to environmental conditions. Aquatic vegetation can show apparent plasticity regarding Si uptake, adaptive to water and wind dynamics, light interception, herbivory and nutrient stress. Beyond a plant physiological viewpoint, high Si uptake results in high BSi in plant litter, which can impact on aquatic decomposition processes. Si content in aquatic vegetation shows intriguing relations with other strength components such as cellulose and lignin. Si content has also been linked to fungal and microbial community, litter stoichiometry and invertebrate shredders: all factors that potentially influence organic turnover in aquatic sediments. Uptake of Si by aquatic vegetation is thus not only an important transient sink for Si in the global biogeochemical Si cycle, it can also affect carbon turnover in aquatic ecosystems. Experimental and field studies should be conducted to elucidate controls on aquatic plant Si uptake, especially focusing on interactive effects of multiple biotic and abiotic factors. This review provides an overview of the state‐of‐the‐art knowledge on silicon in aquatic vegetation.

벚나무류 낙화가 인공 연못생태계의 물질순환에 미치는 영향

벚나무류가 식재된 인공 연못에서 벚나무류의 낙화가 연못생태계의 물질순환에 어떠한 영향을 미치는지 확인하기 위해 벚꽃이 분해되는 기간을 달리하여 마이크로코즘 실험을 수행하였다. 벚나무류의 꽃잎을 넣은 망(mesh)의 크기가 <TEX>$1mm^2$</TEX>인 나일론 꽃잎주머니를 제작하였다. 플라스틱 통을 하나의 마이크로코즘 단위로 하여 인공 연못의 유입수를 채우고, 꽃잎주머니를 넣은 처리구와 넣지 않은 대조구를 설정하였다. 처리구에서 꽃잎주머니를 수거하는 시기를 달리한 결과, 실험이 끝난 후 벚꽃잎은 초기 건중량의 32.3%만이 남았으며, 분해율(k)은 <TEX>$7.06{\times}10^{-2}day^{-1}$</TEX>로 나타났다. 벚꽃잎이 분해된 물의 <TEX>$NO_3-N$</TEX> 농도는 1.90 mg/L에서 처음 4일 후 급격히 감소하여 0.02 mg/L를 나타낸 반면, <TEX>$NH_4-N$</TEX> 농도는 0.03 mg/L에서 분해가 진행되는 동안 계속적으로 증가하여 2.85 mg/L를 나타냈다. <TEX>$PO_4-P$</TEX> 농도는 0.03 mg/L에서 꽃잎의 분해에 의해 2.39 mg/L까지 증가하여, 인이 질소에 비해 상대적으로 높은 비율이 무기형태로 용탈되고 있음을 알 수 있다. 인공 연못에 쌓이는 벚꽃의 양을 추산하고 용탈되는 가용성 질소와 인의 양을 예상한 결과, 벚꽃잎이 분해되어 물에 녹아나온 가용성 인은(0.02 mg/L 증가) 인공 연못의 부영양화를 유발할 수 있는 것으로 판단된다. To identify the effect of fallen cherry blossom on the artificial pond ecosystem, microcosm experiment was conducted into the aquatic decomposition of Prunus species petals. Petals were put in <TEX>$1mm^2$</TEX> mesh nylon litter bags. For treatment group, one flower litter bag was placed into each pot microcosm (<TEX>$27{\times}20{\times}8cm^3$</TEX>) filled with influent water from the artificial pond, whereas control group microcosm contained pond water only. Decomposition time were set differently (4, 8, 12, 16 days) among treatment groups. At the end of experiment, most petals were decomposed and only 32.3% of initial dry weight remained with the decay rate (k) of <TEX>$7.06{\times}10^{-2}day^{-1}$</TEX>. <TEX>$NO_3-N$</TEX> concentration of microcosm water decreased sharply from 1.90 mg/L at first to 0.02 mg/L, whereas <TEX>$NH_4-N$</TEX> concentration increased from 0.03 mg/L to 2.85 mg/L continually. <TEX>$PO_4-P$</TEX> concentration was 0.03 mg/L at first and increased to 2.39 mg/L by decomposition. Therefore, available phosphorus seems to have leached with higher rate than nitrogen from the petals litter. Increase about 0.02 mg/L in <TEX>$PO_4-P$</TEX> concentration could be estimated in artificial pond from the calculation on the total quantity of fallen blossoms. This result suggests that available phosphorus from the decomposed Prunus petals could cause eutrophication in the artificial pond.

Cascading effects of induced terrestrial plant defences on aquatic and terrestrial ecosystem function.

Herbivores induce plants to undergo diverse processes that minimize costs to the plant, such as producing defences to deter herbivory or reallocating limited resources to inaccessible portions of the plant. Yet most plant tissue is consumed by decomposers, not herbivores, and these defensive processes aimed to deter herbivores may alter plant tissue even after detachment from the plant. All consumers value nutrients, but plants also require these nutrients for primary functions and defensive processes. We experimentally simulated herbivory with and without nutrient additions on red alder (Alnus rubra), which supplies the majority of leaf litter for many rivers in western North America. Simulated herbivory induced a defence response with cascading effects: terrestrial herbivores and aquatic decomposers fed less on leaves from stressed trees. This effect was context dependent: leaves from fertilized-only trees decomposed most rapidly while leaves from fertilized trees receiving the herbivory treatment decomposed least, suggesting plants funnelled a nutritionally valuable resource into enhanced defence. One component of the defence response was a decrease in leaf nitrogen leading to elevated carbon : nitrogen. Aquatic decomposers prefer leaves naturally low in C : N and this altered nutrient profile largely explains the lower rate of aquatic decomposition. Furthermore, terrestrial soil decomposers were unaffected by either treatment but did show a preference for local and nitrogen-rich leaves. Our study illustrates the ecological implications of terrestrial herbivory and these findings demonstrate that the effects of selection caused by terrestrial herbivory in one ecosystem can indirectly shape the structure of other ecosystems through ecological fluxes across boundaries.

Invertebrate grazers are a crucial factor for grass litter mass loss and nutrient mobilization during aquatic decomposition

The decomposition process of plant litter is very important for carbon turnover. Much is known about the impact of invertebrate shredders on this process, but the effect of invertebrate grazers (e.g. detritivore freshwater snails) on litter processing has received little attention. These grazers are quite prevalent in some aquatic ecosys- tems. Therefore, a laboratory batch experiment was conducted to assess the effect of invertebrate grazers (aquatic snails) on aquatic litter decomposition and nutrient mobilization. Litter containing different amounts of silicon was used because silicon content is known to affect grazers. Invertebrate grazers had a significant effect on litter de- composition, increasing leaf mass loss by 100 % and reducing the cellulose content by 25 %. The leaf litter silicon content had no effect on these grazers. Furthermore, litter silicon content showed strong negative effects on nutrient remobilization, whereas the mobilization of calcium, nitrogen and DOC was affected by the invertebrates. It could be concluded that invertebrate grazer may have an important role in aquatic litter decomposition by decreasing litter cellulose content and enhancing mobilization of nutrients.

Synergistic effects of the invasive Chinese tallow (Triadica sebifera) and climate change on aquatic amphibian survival

Changes in climate and the introduction of invasive species are two major stressors to amphibians, although little is known about the interaction between these two factors with regard to impacts on amphibians. We focused our study on an invasive tree species, the Chinese tallow (Triadica sebifera), that annually sheds its leaves and produces leaf litter that is known to negatively impact aquatic amphibian survival. The purpose of our research was to determine whether the timing of leaf fall from Chinese tallow and the timing of amphibian breeding (determined by weather) influence survival of amphibian larvae. We simulated a range of winter weather scenarios, ranging from cold to warm, by altering the relative timing of when leaf litter and amphibian larvae were introduced into aquatic mesocosms. Our results indicate that amphibian larvae survival was greatly affected by the length of time Chinese tallow leaf litter decomposes in water prior to the introduction of the larvae. Larvae in treatments simulating warm winters (early amphibian breeding) were introduced to the mesocosms early in the aquatic decomposition process of the leaf litter and had significantly lower survival compared with cold winters (late amphibian breeding), likely due to significantly lower dissolved oxygen levels. Shifts to earlier breeding phenology, linked to warming climate, have already been observed in many amphibian taxa, and with most climate models predicting a significant warming trend over the next century, the trend toward earlier breeding should continue if not increase. Our results strongly suggest that a warming climate can interact with the effects of invasive plant species, in ways we have not previously considered, to reduce the survival of an already declining group of organisms.

Silicon controls microbial decay and nutrient release of grass litter during aquatic decomposition

The decomposition rate of plant litter is important for the carbon cycle. Element stoichiometry and hardly degradable carbon compounds are main factors controlling the decomposition rate of plant litter. Recent research has linked these factors to silicon availability during plant growth, but no research focused on the effect of silicon on litter decomposition. We therefore conducted a batch experiment to assess the effect of silicon availability to plants on litter degradation, nutrient release and multi elemental stoichiometry. Experiments were conducted in the presence or absence of invertebrate shredders (Gammarus pulex). We show that nutrient content (affected by silicon availability during plant growth) has a strong impact on nutrient turnover, while DOC, N, and Mn were mainly controlled by invertebrate feeding. The carbon turnover during microbial litter decay was strongly influenced by the silicon availability during plant growth, with quicker potential C turnover of litter with higher silicon content. In both Si-rich and Si-poor litter, feeding by invertebrate shredders positively impacted turnover rates, but effects were less pronounced in Si-rich litter. It can be concluded that silicon availability in wetlands dominated by reed plays an important role in carbon sequestration, nutrient cycling, and remobilization during aquatic litter decay.

Comparison of Protocols for Measuring and Calculating Postmortem Submersion Intervals for Human Analogs in Fresh Water

Protocols for determining postmortem submersion interval (PMSI) have long been problematic for forensic investigators due to the wide variety of factors affecting the rate of decomposition of submerged carrion. Likewise, it has been equally problematic for researchers to develop standardized experimental protocols to monitor underwater decomposition without artificially affecting the decomposition rate. This study compares two experimental protocols: (i) underwater in situ evaluation with photographic documentation utilizing the Heaton etal. total aquatic decomposition (TAD) score and (ii) weighing the carrion before and after submersion. Complete forensic necropsies were performed as a control. Perinatal piglets were used as human analogs. The results of this study indicate that in order to objectively measure decomposition over time, the human analog should be examined at depth using the TAD scoring system rather than utilizing a carrion weight evaluation. The acquired TAD score can be used to calculate an approximate PMSI.

Metal/metalloid fixation by litter during decomposition affected by silicon availability during plant growth

Organic matter is known to accumulate high amounts of metals/metalloids, enhanced during the process of decomposition by heterotrophic biofilms (with high fixation capacity for metals/metalloids). The colonization by microbes and the decay rate of the organic matter depends on different litter properties. Main litter properties affecting the decomposition of organic matter such as the nutrient ratios and the content of cellulose, lignin and phenols are currently described to be changed by silicon availability. But less is known about the impact of silicon availability during plant growth on elemental fixation during decay. Hence, this research focuses on the impact of silicon availability during plant growth on fixation of 42 elements during litter decay, by controlling the litter properties. The results of this experiment are a significantly higher metal/metalloid accumulation during decomposition of plant litter grown under low silicon availability. This may be explained by the altered litter properties (mainly nutrient content) affecting the microbial decomposition of the litter, the microbial growth on the litter and possibly by the silicon double layer, which is evident in leaf litter with high silicon content and reduces the binding sites for metals/metalloids. Furthermore, this silicon double layer may also reduce the growing biofilm by reducing the availability of carbon compounds at the litter surface and has to be elucidated in further research. Hence, low silicon availability during plant growth enhances the metal/metalloid accumulation into plant litter during aquatic decomposition.

Genotype and soil nutrient environment influence aspen litter chemistry and in-stream decomposition

A growing body of genes-to-ecosystems research has documented the ecosystem-level consequences of intraspecific variation in plants caused in large part by variation in chemical composition. Understanding how this genetic variation in trees might interact with elevated nutrients resulting from increases in anthropogenic deposition may give us insight into how future riparian forests might influence adjacent streams through leaf-litter deposition. We examined the effects of tree genotype, soil nutrient environment, and their interaction on aspen (Populus tremuloides) litter chemistry and aquatic decomposition. We used litter collected from 5 aspen genotypes grown in a common garden under low and high nutrient availability and monitored decomposition over 112 d in a woodland stream. Genotype, environment, and genotype × environment interactions influenced litter chemistry and decomposition dynamics. Genotype and environment both strongly influenced initial litter chemistry, with significant genotype × environment interactions for bound condensed tannins and C∶N. Consistent with effects on litter chemistry, decomposition rates were significantly affected by genotype, environment, and genotype × environment interactions. These results suggest that future changes in intraspecific genetic variation of tree species and deposition of nutrients because of shifts in climate, land use, and related factors may influence decomposition processes in terrestrial systems and in the aquatic systems with which they are coupled via material transfer.

Species diversity and decomposition in laboratory aquatic systems: the role of species interactions

Summary1. Interest in the effects of biodiversity on ecosystem processes is increasing, stimulated by the global species decline. Different hypotheses about the biodiversity‐ecosystem functioning (BEF) relationship have been put forward and various underlying mechanisms proposed for different ecosystems.2. We investigated BEF relationships and the role of species interactions in laboratory experiments focussing on aquatic decomposition. Species richness at three different trophic levels (leaf detritus, detritus‐colonising fungi and invertebrate detritivores) was manipulated, and its effects on leaf mass loss and fungal growth were assessed in two experiments. In the first, monocultures and mixtures of reed (Phragmites australis), alder (Alnus glutinosa) and oak (Quercus cerris) leaf disks were incubated with zero, one or eight fungal species. Leaf mixtures were also incubated with combinations of three and five fungal species. In the second experiment, reed leaf disks were incubated with all eight fungal species and offered to combinations of one, two, three, four or five macroinvertebrate detritivores with different feeding modes.3. Results from the first experiment showed that leaf mass loss was directly related to fungal mass and varied unimodally with the number of fungi, with a maximum rate attained at intermediate diversity in oak and reed and at maximum diversity in alder (the fastest decomposing leaf).4. Mixing litter species stimulated fungal growth but interactions between species of fungi slowed down decomposition. In contrast, mixtures of macroinvertebrate detritivores reduced fungal mass and accelerated leaf decomposition. Possible explanations of the positive relationship between detritivore diversity and decomposition are a reduction in fungal dominance and a differentiation in the use of different resource patches promoted by higher fungal diversity.5. In conclusion, the results show a general increase in decomposition rate with increasing biodiversity that is controlled by within‐ and between‐trophic level interactions, and support the hypothesis of both bottom‐up and top‐down effects of diversity on this process.

Effects of the Sand Bar Breaching on Typha domingensis (PERS.) in a Tropical Coastal Lagoon

Coastal lagoons are usually subjected to several kinds of human impacts, especially eutrophication. The breaching of the sand bar, which separates the lagoon from the ocean, by human action, is a common process used to decrease the negative effects of eutrophication. The aims of this research were to evaluate the effects of the artificial sand bar breaching on the populations of the aquatic macrophyte Typha domingensis and the subsequent effects on nutrients concentration in a tropical coastal lagoon. Samplings were carried out monthly from February/01 to January/02 in a monospecific stand of T. domingensis at Imboassica lagoon (Rio de Janeiro/Brazil). Two sampling sites, in the middle and in the border of the stand, were marked in three different transects. Water depth was measured and the aerial biomass sampled with a 0.25 m2 quadrat. The macrophyte samples were separated into live and dead material and the shoot length, shoot density and number of leaves were analyzed. All plant material was oven dried till constant weight and net primary production, dead stand crop production and the nutrients release through decomposition were estimated at each site. The decrease in water level due to sand bar opening affected negatively T. domingensis populations, but the most intense effects were observed in the middle of the stand. The shoot mortality was highly enhanced after the sand bar breaching and the nutrients were released through decomposition to the water column. It reflected on an input of 11.5 kg C m−2, 0.22 kg N m−2 and 0.13 kg P m−2 into the lagoon, which represent from 22.5 to 44.8 ton P and 35.9 to 71.8 ton N to the lagoon. The decrease of nutrients concentration after the sand bar breaching was not successfully accomplished. The decay of T. domingensis stands due to the sand bar breaching neutralized the exportation of nutrients to the ocean, and contributed to the phosphorous increase in the water column. Thus, to a better management of aquatic ecosystems subjected to human eutrophication, the role of aquatic macrophytes decomposition on internal fertilization of aquatic ecosystems should be accounted.

On the patterns of biomass transfer in the benthic fauna of an amazonian black-water river, as evidenced by 32P label experiment

Leaf litter colonised by aquatic decomposition fungi was labelled with Na2H32PO4 and placed in a submerged litter bank in the Central Amazonian river Taruma-Mirim. Of a total of 540 animals subsequently collected and analysed, 17% were definitely labelled. The phase-spatial pattern of label indicated that most species, notably fish and shrimps, were territorial with a radius of movement rarely exceeding 1 m; while chironomids and other microfauna are virtually stationary. From the distribution of labelled individuals within the litter bank and the gradual buildup of label it seems the fish feed within the same small area over periods of several weeks. The appearance of label in the shrimps was more erratic. The 32P appeared to be firmly retained within the living cells throughout the experiment and passed via the foodchains previously established by analysis of gut contents. The observed predator/prey density and foraging pattern have important implications for competition theory and the maintainance of species richness.

The effect of nutrients on aquatic plant decomposition rates

The effect of nutrients on aquatic plant decomposition rates

Changes in the chemical composition of alder, poplar and willow leaves during decomposition in a river

(1) As there was a paucity of information on the aquatic decomposition of leaves of willow (Salix alba), poplar (Populus gr. nigra) and alder (Alnus glutinosa), the net-bag technique was used to study chemical changes in the leaves over a period of six months in the Garonne (France). (2) The disappearance rates of foliar organic matter were about similar for the three species (k = 0.0065 day−1 for alder, k = 0.0054 day−1 for poplar and k = 0.0050 day−1 for willow). Changes in carbon amount were comparable to those of organic matter. Nitrogen and organic phosphorus accumulated during the first months of decomposition. The C/N ratios of foliar matter changed in the same way in the three species, falling steeply for the first month, then levelling off. Amounts of sugar disappeared very rapidly, particularly for alder and willow. Cellulose concentrations were constant throughout the whole decomposition process whilst an increase in the amounts of lignin was observed during the first months; however the latter could be due to an interference by microbial compounds. (3) The changes of some constituents, such as carbon, sugars and cellulose, were described with exponential or multiexponential models. Despite the very different initial ratios of C/N and lignin/N, these changes associated with leaf decomposition were similar for the three species.

AN EVALUATION OF PIGMENTED NYLON FILM FOR USE IN AQUATIC PLANT MANAGEMENT

ABSTRACT Experimental applications of pigmented nylon film were conducted in the Seattle metropolitan area in order to evaluate gas venting characteristics and instalation procedures. The material was highly effective in controlling aquatic plant growth, causing death and decomposition of covered plant materials in 30 to 35 days. Gas entrappment, ballooning, and lifting was observed with unvented material but this was overcome by placing venting slits in the material. A vent slit design of 12/meter2gave the best result. Installation of the film is straightforward and simple. Difficulties encountered with dense plant growth and soft organic sediments are described.