Benthic Algal Research Articles

Marine Benthic Algal Composition after 45 Years in an Urbanized Bay in Cebu, Philippines

Coastal ecosystems have been seriously impacted by anthropogenic activities, which are compounded by recent climatic and environmental changes. To provide some evidence of these changes, a study of marine benthic algal composition was conducted by comparing historical (1969–1970) and contemporary (2013–2014) collections in Silot Bay in Cebu, Philippines. A quantitative survey revealed a total of 30 species of benthic algae (11 red, nine brown, and 10 green) in the historical collections, whereas only 15 species (four each of red and brown plus seven species of green algae) were accounted in the latter years. This decline in the marine benthic algal composition may be attributed to sedimentation, which is indirectly caused by urbanization and human population increase. Altered environmental conditions inside the Bay may also explain the decline and qualitative changes of algal species composition therein. Continued monitoring of the benthic macroalgal composition and environmental parameters may help document anthropogenic impacts on marine ecosystems. Historical herbarium samples represent a valuable yet underappreciated resource for tracking environmental changes through time.

Marine Benthic Algal Community in Geumodo at Dadohaehaesang National Park, Central South Coast of Korea

다도해해상국립공원 금오도지역의 해조군집에 대해서 2017년 2월부터 8월까지 3 계절동안 금오도 직포와 안도에서 조사를 실시하였다. 조사결과 총 104종(녹조류 16종, 갈조류 24종, 홍조류 64종)의 해조류가 분포하였으며, 직포에서 82종, 안도에서 72종이 출현하였다. 해조류 생물량은 직포에서 평균 203.50 g dry weight/㎡, 안도에서 평균 212.67 g dry weight/㎡ 이었다. 중요도(IV)에 따른 우점종은 구멍갈파래(Ulva australis), 지충이(Sargassum thunbergii), 돌가사리(Chondracanthus tenellus) 등으로 나타났다.

Marine Benthic Algal Community at Dadohaehaesang National Park, South-west Coast of Korea

Marine Benthic Algal Community at Dadohaehaesang National Park, South-west Coast of Korea

Benthic algal (periphyton) growth rates in response to nitrogen and phosphorus: Parameter estimation for water quality models.

Nitrogen (N) and phosphorus (P) are significant pollutants that can stimulate nuisance blooms of algae. Water quality models (e.g., WASP, CE-QUAL-R1, CE-QUAL-ICM, QUAL2k) are valuable and widely used management tools for algal accrual due to excess nutrients in the presence of other limiting factors. These models utilize the Monod and Droop equations to associate algal growth rate with dissolved nutrient concentration and intra-cellular nutrient content. Having accurate parameter values is essential to model performance, however published values for model parameterization are limited, particularly for benthic (periphyton) algae. We conducted a 10-day mesocosm experiment and measured diatom-dominated periphyton biomass accrual through time as chlorophyll a (chl a) and ash-free dry mass (AFDM) in response to additions of N (range 5-11,995 μg NO3-N/L) and P (range 0.89-59.51 μg SRP/L). Resulting half saturation coefficients and growth rates are similar to other published values, but minimum nutrient quotas are higher than those previously reported. Saturation concentration for N ranged from 150 to 2450 μg NO3-N/L based on chl a and from 8.5 to 60 μg NO3-N/L when based on AFDM. Similarly, the saturation concentration for P ranged from 12 to 29 μg-P/L based on chl a, and from 2.5 to 6.1 μg-P/L based on AFDM. These saturation concentrations provide an upper limit for streams where diatom growth can be expected to respond to nutrient levels and a benchmark for reducing nutrient concentrations to a point where benthic algal growth will be limited.

Effects of flow regime on benthic algae and macroinvertebrates - A comparison between regulated and unregulated rivers.

Natural fluctuations in flow are important for maintaining the ecological integrity of riverine ecosystems. However, the flow regime of many rivers has been modified. We assessed the impact of water chemistry, habitat and streamflow characteristics on macroinvertebrates and benthic algae, comparing 20 regulated with 20 unregulated sites. Flow regime, calculated from daily averaged discharge over the five years preceding sampling, was generally more stable at regulated sites, with higher relative discharges in winter, lower relative discharges in spring and smaller differences between upper and lower percentiles. However, no consistent differences in benthic algal or macroinvertebrate structural and functional traits occurred between regulated and unregulated sites. When regulated and unregulated sites were pooled, overall flow regime, calculated as principal components of discharge characteristics over the five years preceding sampling, affected macroinvertebrate species assemblages, but not indices used for ecosystem status assessment or functional feeding groups. This indicates that, while species identity shifted with changing flow regime, the exchanged taxa had similar feeding habits. In contrast to macroinvertebrates, overall flow regime did not affect benthic algae. Our results indicate that overall flow regime affected the species pool of macroinvertebrates from which recolonization after extreme events may occur, but not of benthic algae. When individual components of flow regime were analyzed separately, high June (i.e. three months before sampling) flow maxima were associated with low benthic algal taxon richness, presumably due to scouring. Macroinvertebrate taxon richness decreased with lower relative minimum discharges, presumably due to temporary drying of parts of the riverbed. However, recolonization after such extreme events presumably is fast. Generally, macroinvertebrate and benthic algal assemblages were more closely related to water physico-chemical than to hydrological variables. Our results suggest that macroinvertebrate and benthic algal indices commonly used for ecological status assessment are applicable also in regulated rivers.

Integrating Seasonal Information on Nutrients and Benthic Algal Biomass into Stream Water Quality Monitoring

AbstractBenthic chlorophyll a (BChl a) and environmental factors that influence algal biomass were measured monthly from February through October in 22 streams from three agricultural regions of the United States. At‐site maximum BChl a ranged from 14 to 406 mg/m2 and generally varied with dissolved inorganic nitrogen (DIN): 8 out of 9 sites with at‐site median DIN >0.5 mg/L had maximum BChl a >100 mg/m2. BChl a accrued and persisted at levels within 50% of at‐site maximum for only one to three months. No dominant seasonal pattern for algal biomass accrual was observed in any region. A linear model with DIN, water surface gradient, and velocity accounted for most of the cross‐site variation in maximum chlorophyll a (adjusted R2 = 0.7), but was no better than a single value of DIN = 0.5 mg/L for distinguishing between low and high‐biomass sites. Studies of nutrient enrichment require multiple samples to estimate algal biomass with sufficient precision given the magnitude of temporal variability of algal biomass. An effective strategy for regional stream assessment of nutrient enrichment could be based on a relation between maximum BChl a and DIN based on repeat sampling at sites selected to represent a gradient in nutrients and application of the relation to a larger number of sites with synoptic nutrient information.

Why does Cladophora fail to reach nuisance proportions in Lake Simcoe?

In recent years, a resurgence of filamentous benthic algae (e.g., Cladophora) in the Laurentian Great Lakes has been perceived as a consequence of dreissenid mussel invasion and subsequent alterations to ecosystem nutrient and energy cycling. Here, we employ high-frequency hydro acoustic surveys at two sites in Lake Simcoe to assess the presence and extent of excessive benthic algal ( Cladophora) growth that we hypothesized would be growing on hard substrate in the post dreissenid mussel period. Despite comparable dreissenid abundance, water clarity and phosphorus concentrations to sites in the lower Great Lakes known to suffer extensive Cladophora fouling during the summer months, the nuisance growths of Cladophora that have become a seasonal phenomenon in the lower Great Lakes were not found at survey sites in Lake Simcoe. While the proximal cause for the lack of excessive Cladophora growth in Lake Simcoe remains elusive, in this paper, we highlight some distinct differences in environmental conditions and ecological interactions that might make near shore areas of Lake Simcoe unique from near shore areas of the lower Great Lakes. Overall, the results of this study and other recent studies in Lake Simcoe are not inconsistent with the near shore shunt hypothesis that predicts dreissenid mussels enrich the benthic environment, but the manifestation in Lake Simcoe is very different than that observed in the lower Great Lakes.

Food competition between the benthic polychaeteHediste diversicolorand the semipelagic mysidNeomysis integerin the northern Baltic Sea

INTRODUCTION As the structure of benthic communities in the Baltic Sea is relatively simple, the area offers a unique opportunity to study the mechanisms and detect the driving forces of changes in biodiversity. Nevertheless, scientists are still debating about the relative contribution of biotic interactions and physical disturbance in determining the patterns of coastal communities in the northern Baltic Sea. Earlier studies demonstrated significant intra- and interspecific competitive links among several benthic algal and invertebrate species in the region (Kotta et a1., 2001, 2008; Orav-Kotta et al., 2009). Other studies, however, supported an alternative view that physical disturbance is the main mechanism of community dynamics in the northern Baltic Sea region (e.g. Kautsky & van der Maarel, 1990; Herkul et al., 2006). Earlier studies have focussed on the competitive links either between benthic or pelagic species. To date, there are virtually no studies where the competitive interactions between benthic and pelagic species are experimentally evaluated although such benthic--pelagic coupling might be relevant in many instances. Neomysis integer (Leach) is the most prevalent mysid species in the coastal areas of the northern Baltic Sea (Kotta & Kotta, 1999). In May-June the bulk of the population is concentrated in the shallow areas below the 10 m depth. In the less exposed bays the density of mysids may occasionally exceed 10 000 ind. [m.sup.2]. It is likely that in such shallow areas the density of plankton is low and the food should be primarily obtained from the upper layer of the sediment. Neomysis integer is considered to be omnivorous. It is known to feed besides phytoplankton and zooplankton on bottom detritus and filamentous algae (Mauchline, 1971). The polychaete Hediste diversicolor (O. F. Muller) is the key benthic invertebrate species in these shallow and isolated bays. The species is a deposit feeder at juvenile stages and a predator at the later stages of its development (Bonsdorff & Pearson, 1999). Hence, competition between the species is likely in these areas. The aim of this study was to investigate if the two species are competing for space and food during May-June when the densities of both species are very high in the shallow bays. We expect that at low food levels the competitive interactions reduce the growth and survival of the test organisms whereas at high food levels such negative effects do not occur. MATERIAL AND METHODS The in situ food competition between the prevalent mysid N. integer and the polychaete N. diversicolor was studied in a shallow (2 m) bay (59[degrees]50'N, 23[degrees]15'E) adjacent to the Tvarminne Zoological Station in the north-eastern Baltic Sea. The bay is moderately exposed to the sea and the prevailing sediment is silty sand. The test organisms and sediment were collected in the vicinity of the experimental site. The sediment was sieved through a 1 mm mesh and dried in the sun for 3 days to assure that it was free from living benthic invertebrates. To investigate interspecific interactions between the test organisms, 3 L plastic buckets ([empty set] 18 cm) were used. The buckets were filled with an 8 cm layer of sediment and a 7 cm layer of seawater and allowed to settle for 6 h. The test organisms were added to four replicate buckets per treatment (totalling 24 buckets). Four individuals of H. diversicolor and/or 15 individuals of N. integer were added to each bucket so that their densities corresponded to natural densities in the study area. The animals were fed by adding sediment rich in detritus and microphytobenthos. A more detailed setup of the experiment is given in Table 1. The buckets were closed by a mesh-net (0.2 mm mesh size) to minimize the risk of migration but at the same time to assure sufficient water exchange in the buckets. The experimental buckets were randomly placed on the seafloor at a depth of 0. …

Consequences of Livestock Grazing on Water Quality and Benthic Algal Biomass in a Canadian Natural Grassland Plateau

The effects of livestock grazing on selected riparian and stream attributes, water chemistry, and algal biomass were investigated over a two-year period using livestock enclosures and by completing stream surveys in the Cypress Hills grassland plateau, Alberta, Canada. Livestock enclosure experiments, partially replicated in three streams, comprised four treatments: (1) early season livestock grazing (June-August), (2) late season livestock grazing (August-September), (3) all season grazing (June-September), and (4) livestock absent controls. Livestock grazing significantly decreased streambank stability, biomass of riparian vegetation, and the extent to which aquatic vegetation covered the stream channels compared with livestock-absent controls. Water quality comparisons indicated significant differences among the four livestock grazing treatments in Battle and Graburn creeks but not in Nine Mile Creek. In Graburn Creek, the concentration of total phosphorus in the all-season livestock grazing treatment was significantly higher than that in the livestock-absent control, and the early season and late season grazing treatments. Concentrations of soluble reactive phosphorus in the all-season livestock grazing treatment also exceeded that in livestock-absent control. In contrast, differences in water quality variables in the remaining 22 comparisons (i.e., 22 of the total 24 comparisons) were minor even when differences were statistically significant. Effects of livestock grazing on algal biomass were variable, and there was no consistent pattern among creeks. At the watershed scale, spatial variation in algal biomass was related (P < 0.05) with concentrations of NO(2)(-) + NO(3) (-) and soluble reactive phosphorus in two of the four study creeks. Nutrient diffusing substrata experiments showed that algal communities were either nitrogen-limited or not limited by nutrients, depending on stream and season.

Nitrogen and phosphorus relationships to benthic algal biomass in temperate streams

Knowledge of factors limiting benthic algal (periphyton) biomass is central to understanding energy flow in stream ecosystems and stream eutrophication. We used several data sets to determine how water column nutrients and nonnutrient factors are linked to periphytic biomass and if the ecoregion concept is applicable to nutrient–periphyton relationships. Literature values for seasonal means of biomass of periphyton, nutrient concentrations, and other stream characteristics were collected for almost 300 sampling periods from temperate streams. Data for benthic chlorophyll and nutrient concentrations from a subset of 620 stations in the United States National Stream Water-Quality Monitoring Networks were also analyzed. The greatest portion of variance in models for the mean and maximum biomass of benthic stream algae (about 40%) was explained by concentrations of total N and P. Breakpoint regression and a two-dimensional Kolmogorov–Smirnov statistical technique established significant breakpoints of about 30 µg total P·L–1 and 40 µg total N·L–1, above which mean chlorophyll values were substantially higher. Ecoregion effects on nutrient–chlorophyll relationships were weak. Ecoregion effects were cross-correlated with anthropogenic effects such as percent urban and cropland area in the watershed and population density. Thus, caution is necessary to separate anthropogenic effects from natural variation at the ecoregion level.

The effects of salt marsh haying on benthic algal biomass.

Salt marsh haying is a traditional activity on East Coast salt marshes and is still carried out on a large scale (over 400 hectares regularly) throughout Plum Island Sound, located in northeastern Massachusetts. The removal of approximately 90% of the aboveground biomass of the salt marsh by haying may alter many ecological processes within the salt marsh (1). One such process is the production of benthic algae. Estrada et al. (1974) found that nutrients and light are critical controls on the amount of benthic algae present (2). When a thick grass canopy shades the algae, their growth is limited not by nutrients but rather by the available light. However, when little grass canopy is present, benthic algal growth is limited by the available nutrients. Grazers are also likely to determine the amount of algal standing crop. In this project we tested the hypothesis that there should be a marked increase in benthic algal biomass after an area has been hayed because the algae is no longer limited by the available light. We took core samples at three marsh sites, each about 1 to 2 hectares in area. Two of these are regularly subjected to haying, and one is an unhayed reference area. The reference area (PUH) has not been hayed for at least 25 years. One hayed site (EPH) was last hayed two summers ago (1999). At PUH and EPH, six 1-m quadrats were placed randomly in two different vegetation zones, Spartina alterniflora (low marsh) and Spartina patens (high marsh) sites. Three quadrats in each vegetation zone at each area were cleared of aboveground vegetation by clipping, and three were left as unclipped reference quadrats. The second hayed site (HAY) was hayed in June 2001 before sampling began. At HAY, we established three 1-m quadrats within Spartina patens zones that had just been cleared of vegetation by the hayer. Six sediment cores (3-cm diameter, 1-cm depth) were taken from each quadrat at day 0, day 7, day 14, and day 30 after clipping (or haying). The six sediment cores were then pooled together into two sets of three cores. At the end of the 30-day sampling period, the aboveground plant biomass from the quadrats within the hayed and reference sites was removed to measure the regrowth of the vegetation during the experimental period. The material from the sites was then dried and weighed. The benthic chlorophyll was extracted and measured from the pooled core samples using the method of Lorenzen (3). We used HOBO HLI light intensity loggers to determine the relative amount of light reaching the sediment surface at both the treatment and reference sites. We found no difference between the benthic algal chlorophyll in the area that was hayed two summers ago and the area that has not been hayed for 25 years. Consequently, we pooled and treated the two areas as replicates in further analyses. Furthermore, we found no statistically consistent increase in algal biomass over the 30 days of the experiment in the clipped or hayed treatments. In addition, there was not a significant difference in benthic algal biomass between S. alterniflora (low marsh) and S. patens (high marsh) zones regardless of whether they were clipped or not (Fig. 1). The benthic chlorophyll concentrations in the June 2001 hayed area were significantly higher than the benthic chlorophyll in the unclipped treatments (ANOVA, F 5 3.330, P 5 0.039). However, neither the benthic algal chlorophyll present in the hayed area nor that in the reference quadrats was significantly different from that present in the clipped quadrats. The results suggest that haying on a large scale, but not small-scale removal of the plant canopy, increases the amount of benthic algae present. Based on a limited number of light measurements, there is a direct relationship between the percentage of light reaching the sediment surface and benthic chlorophyll concentrations within each quadrat (Fig. 2). In addition, it appears that there is an inverse relationship between the plant biomass of each quadrat and the benthic chlorophyll concentration (Fig. 2). 1 Governor Dummer Academy, Byfield, MA. 2 Massachusetts Audubon Society, Wenham, MA.

WHOLE-LAKE FERTILIZATION EFFECTS ON DISTRIBUTION OF PRIMARY PRODUCTION BETWEEN BENTHIC AND PELAGIC HABITATS

The perception that primary production in lakes is positively related to phosphorus loading is based almost entirely on studies of phytoplankton. This is partly because benthic and pelagic habitats in lakes are often treated as separate ecosystems, the processes of which can be evaluated independently. However, light and nutrients often limit primary producers in both benthic and pelagic habitats. We tested the hypothesis that reductions in light associated with increases in phytoplankton could cause compensatory decreases in benthic algal (periphyton) primary production. We monitored production of periphyton on sediments (epipelon), periphyton on wood (epixylon), and phytoplankton in four lakes in upper Michigan, USA, from 1991 to 1995. During the summers of 1993–1995, we stimulated phytoplankton production in three of the lakes by fertilizing with nitrogen and phosphorus (N:P ≥ 25 by atoms) at rates between 0.3 and 2.0 mg P·m−3·d−1. The response of periphyton to fertilization was substratum specific: epixylon increased with fertilization, but epipelon decreased. However, when area-specific production was extrapolated to the whole-lake scale, epixylon never constituted >4% of benthic primary production. Thus, the decline in epipelic production dominated the benthic response to fertilization. We also estimated whole-lake (epipelon + phytoplankton) primary production. Epipelic algae constituted 50–80% of whole-lake primary production at ambient nutrient levels. However, only 10–40% of primary production was benthic at the highest fertilization rates. The increase in whole-lake primary production caused by water column fertilization was greatly overestimated when we did not include the compensatory decline in epipelic algae as they were shaded by increases in phytoplankton concentrations.

Caulerpa (Chlorophyta, Caulerpales) from the Kenyan coast

The final goal of our own research is to prepare a Marine Benthic Algal Flora for the Kenyan coast (partim Chlorophyta to start with) including identification keys, detailed original descriptions, taxonomic discussions and numerous illustrations of the morphology as well as anatomical details (drawn by camera lucida)

Produção primária de Pterocladia capillacea (Gelidiaceae - Rhodophyta)

A produção primária de Pterocladia capillacea foi medida através da dosagem de oxigénio (método de Winkler) em condições de laboratório, utilizando-se luz incandescente . Foi discutida em detalhe, uma metodologia adequada para a avaliaçao da produção primaria de algas bentonicas macroscópicas, usando-se frascos transparentes e pretos, com base naquela utilizada para estudos de fitoplâncton. A quantidade de 1,0 ml de alga para frascos com capacidade de 270 ml, temperatura entre 24,0 e 28,0ºC, intensidade luminosa de 40,0 Klux e período de incubação de 2 horas, apresentaram resultados satisfatórios. Esta metodologia pode ser aplicada para algas de morfologia semelhante à de P. capillacea.