Size Structure and Gonad Characterization of <i>Gari elongata</i> (Lamarck 1818) from the Coastal Areas of Hinatuan, Surigao Del Sur, Philippines

Size-structure analyses and gonad characteristics of the elongate sunset clam Gari elongata from the coastal waters of Hinatuan, Surigao del Sur, Philippines, was determined in this study. An opportunistic sampling approach was applied during the collection of G. elongata from the coastal waters of Brgy. Loyola and Brgy. Aquino. A total of 1437 G. elongata individuals were subjected to length-weight measurements, and gonads from five (5) individuals per sex among size classes were processed for histological characterization. The maximum total length of G. elongata recorded is 5.42 cm, way smaller than its congeners elsewhere, which is at 7.0-9.2 cm. The size-structure analysis shows that G. elongata from Brgy. Loyola exhibited negative allometric growth while those gleaned from Brgy. Aquino exhibited positive allometry indicating variation in growth dynamics. Known as a gleaning source, Barangay Loyola is abundant in G. elongata, but individuals are much smaller compared to those gathered from Barangay Aquino. A ratio of 1:1 for male and female classification was observed, as seen from gonad histological analyses. Ovaries were found in the spawning capable state with gonads in ripe (30%), spent (25%), early development (25%), and partially spawning (20%) stages. Testes were found to be in the ripe (40%), early developing (10%), spent (10%), and partially spawning (40%) stages. Gari elongata exhibits spawning capable gonads at 2.85 cm and 2.95 cm for males and females, respectively, which suggests that the shellfish has adapted early to reproduction to maintain its population in the coastal waters of Hinatuan. The small body lengths of individuals with mature gonads indicate that G. elongata may have been exposed to some stress in their natural environment. Regulated management of G. elongata to avoid over-harvesting and assessment of water and sediment quality of their natural habitat is highly recommended

This study determined the influence of the lunar cycle, tidal fluctuation, as well as water physicochemical factors on the gonadal maturation of green mussel, Perna viridis , in Malampaya Sound, Taytay, Palawan, Philippines. Monitoring and sampling were conducted for the 6 months, from October 2017 to March 2018. It was observed that the lunar cycle has a direct influence on gonadal maturity. Gonadal changes in both male and female P. viridis were observed histologically and both exhibit the characteristic of lunar-synchronous pattern. It was observed that a high number of green mussels with spawning stages usually occur during the full moon and new moon. Furthermore, gonadal maturity was also affected by the tidal fluctuation. A higher number of P. viridis with spawning stages were recorded during spring tide, whereas the percentage of spent individuals were higher during neap tides. Furthermore, it was observed in the present study that salinity fluctuation could influence spawning of green mussel, wherein the number of spent individuals increased after the sudden drop in water salinity from 30 to 13 ppt after the heavy rainfall, an indication that spawning had occurred. The presence of individuals with spawning stages was also observed throughout of period of sampling which indicates that mussels were continuously breeding in the area. The highest percentage of individuals having spawning stages were recorded in October and November. The information on the factors that affect gonadal maturation and spawning schedule can help mussel growers predict the schedule of spatfall.

Guest editors Edward Kolodziej, Kyungho Choi, Ruth Marfil-Vega and Bryan Brooks introduce the “Bioanalytical tools for water and sediment quality assessment” themed issue of Environmental Science: Processes & Impacts.

Objective Visual aids like length-frequency histograms are widely used to examine fish population status and trends; however, comparing multiple histograms simultaneously becomes cumbersome and inefficient. Complicating matters further, overlaying covariates on histograms to highlight connections with length frequencies can be challenging. An alternative, and the subject of this Perspective, is to display length distributions as an ordination using similarity indexes; in many cases, this allows for improved visual organization and representation of relationships with covariates. Methods I review the application of ordination methods for analysis of size structures using alternative visualizations that may facilitate the identification of connections that are concealed when analyzing a series of histograms. After a brief introduction to similarity indexes, types of ordinations, and sample sizes, I examine four case studies to illustrate size structure analysis via similarity indices: (1) unconstrained ordination to identify “bass-crowded” populations in a set of 34 small fishing lakes, (2) unconstrained ordination to evaluate the effect of three consecutive length limits on a Largemouth Bass Micropterus nigricans population over a span of 28 years, (3) constrained ordination to assess the relationships between fish community size structure and in-lake and off-lake environmental descriptors in 30 oxbow lakes, and (4) constrained ordination to identify what aspects of Largemouth Bass size structure were related to six types of reservoir habitats. Result Size structure analysis via similarity indexes enabled the exploration of extensive length-frequency data. It is important to acknowledge that ordinations serve solely as a visual aid for assessing size structure—no statistical testing is involved. Conclusion Ordination techniques and software are advancing at a quick pace, holding great promise for the future of size structure analysis via similarity indices.

Development and promulgation of sediment quality criteria represents a substantial challenge for water quality agencies. Unlike water quality programs that rely on individual chemical thresholds to assess water quality, the complex processes affecting contaminant bioavailability in sediments preclude the use of contaminant concentrations to independently assess impacts or identify cause. Various multiple line of evidence approaches (e.g., sediment quality triad) have been developed for sediment quality assessment, but such frameworks are rarely fully incorporated into statewide regulatory programs due to a lack of standardized and validated tools. In 2003, California's State Water Resources Control Board (State Water Board) initiated development of sediment quality criteria and an assessment framework that required the developers to resolve many challenging technical and policy related issues to the satisfaction of stakeholders, scientists, and the general public. The first part of this multiyear effort has been completed and resulted in the development and validation of an integrated collection of tools, thresholds, and a data interpretation framework for assessing sediment contamination impacts on benthic community condition. The State Water Board's narrative sediment quality criteria and assessment framework became effective in 2009, following US Environmental Protection Agency approval. The results of this effort are described in a series of 6 articles published in this issue of Integrated Environmental Assessment and Management. The articles describe: 1) a multiple line of evidence framework for data integration and assessment, 2) calibration and evaluation of sediment quality guidelines for predicting toxic responses, 3) development and evaluation of sediment quality guidelines with respect to benthic macrofauna responses, 4) selection of toxicity test methods and thresholds, 5) identification and characterization of benthic community assemblages, 6) the effect of sampling methods on benthic community assessment, and 7) recommendations on improving the assessment of contaminant exposure in sediment quality assessment. This collection of articles illustrates the steps needed to improve the scientific foundation for sediment quality assessment in regulatory applications.

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 34:139-149 (2004) - doi:10.3354/ame034139 Single-cell analysis of bacterial growth, cell size, and community structure in the Delaware estuary Matthew T. Cottrell*, David L. Kirchman College of Marine Studies, University of Delaware, 700 Pilottown Road, Lewes, Delaware 19958, USA *Email: mattcott@udel.edu ABSTRACT: The abundance and size of thymidine and leucine-assimilating bacteria were examined using a combination of microautoradiography and fluorescence in situ hybridization (micro-FISH) to explore the relationship between community structure and bacterial growth in the Delaware estuary. Community structure varied along the salinity gradient; b-proteobacteria and Cytophaga-like bacteria dominated in freshwater parts of the estuary and α-proteobacteria were the most abundant bacteria at salinities greater than about 10 PSU. The percentage of thymidine and leucine-assimilating bacteria in these groups varied substantially as well, ranging from undetectable to 50% active. The correlation between abundance and the fraction of bacteria assimilating 3H-thymidine was significant for b-proteobacteria, suggesting that the decline in the abundance of these bacteria in high salinity waters was because of slower growth. The correlation between abundance and growth, however, was not significant for the other types of bacteria we examined. Active bacteria were distributed across all size classes, and the smallest bacteria dominated cell number and cell volume. This study indicates that bacterial growth has a smaller impact on community structure than expected, and points towards the importance of other factors, such as mortality, in affecting community structure. KEY WORDS: Proteobacteria · Cytophaga · Microautoradiography · Thymidine · Leucine Full article in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 34, No. 2. Online publication date: February 04, 2004 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2004 Inter-Research.

SUMMARY. 1. The midsummer succession of cladoceran zooplankton in Lake Texoma was examined by demographic characterization of lake populations and a parallel set of life table experiments in which the dominant cladoceran species were raised on naturally occurring lake phytoplankton at lake temperatures. Diaphanosoma leuchtenbergianum occurred throughout the study period (mid June‐mid August 1981) but Daphnia parvula, D. galeata mendotae and Ceriodaphnia lacustris were rarely detected after 15 July.2. Analyses of size structure and size‐specific fecundity of the cladoceran populations showed that (1) size structure shifted to smaller individuals in mid July, (2) size‐specific fecundity was relatively constant in the smaller size classes and was constant or declined in larger females of each species, and (3) size at maturation did not vary significantly during the study of any population.3. Individual growth rates of the two Daphnia species and Ceriodaphnia in the life table experiments were significantly lower in mid July when populations were declining and when size structure of each population was more dominated by smaller Individuals. The reduction in individual growth rates was short‐lived in the life table experiments; growth rates returned to pre‐decline levels by the end of July.4. Two effects of temporary reductions in individual growth rates when size‐specific fecundity and size at maturation are constant are (1) that size structure is temporarily shifted to smaller individuals, and (2) the potential rate of population growth is reduced because of delays in reproduction. Because data on size structure and size‐specific fecundity are commonly used to evaluate the relative effects of predators and resource changes on populations it is noteworthy that erroneous conclusions about the mechanism of population decline may be reached when individual growth rates vary.

Gonad maturity level of the sea cucumber Holothuria scabra is important to note for selection of parent ready spawn. Sea cucumbers are giving a reaction to the treatment of excitatory spawn mature individuals only. For the determination of the level of maturity of gonads of sea cucumbers, the necessary observation of the gonads are microscopic, macroscopic and gonad maturity gonado somatic indeks (GSI). GSI value is important to know the changes that occur in the gonads quantitatively, so that time can be presumed spawning (Effendie, 1997). Reproductive cycle can be determined by observing the evolution of GSI. The study of sea cucumbers Holothuria scabra gonad maturity conducted in Langgur, Southeast Maluku. Observations were made at every cycle of the moon is the full moon phase (BP) and new moon (BB) in the period January 29, 2017 until July 23, 2017. Observations H. scabra gonad maturity level is done with surgery, observation and calculation GSI gonad histology. GSI highest value obtained in May that full moon cycle at 90% of individuals that are in the spawning stage (phase 5), then 70% of the individuals that are in the spawning stage (phase 5) in March that the full moon cycle. The results obtained show that the peak spawning H. scabra period January 2017 to July 2017 occurred on the full moon cycle in May.

The sediment and water of a river can be impacted by the development of modern society. The sediment is responsible for the transport, release and accumulation of toxic compounds and nutrients and can alter the quality of the water. Thus, the objective of this study was to analyze the water and sediment quality of Laranjal stream, located in Laranjal Paulista (Sao Paulo, Brazil). Water and sediment samples were collected in the rainy and dry seasons of the year 2012. The analysis indicated that the sediment presented high content of Cd, Ni, Pb, Cu and Cr. The toxicity test indicated that the river mouth was distinct from the spring and the middle course and the electrical conductivity of the water was high at the sampling point within the urban mesh of Laranjal Paulista. Considering the use and occupation of the Laranjal stream watershed, the rural mes h (dominated by pasture and plantation) influences predominantly the quality of water and sediments.

Diversity and abundance of lepidopteran stem borer natural enemies in natural and cultivated habitats in Botswana

An analysis of the Bulgarian legislation in the field of water and wastewater management harmonized with the European Union's one during the last decade, regarding laws, directives, standards, etc. and its implementation is made. The results of the analysis show that water and wastewater quality assessment and control in Bulgaria are performed according to the legislation. Some modifications of the Bulgarian legislation are still needed. It is emphasized on that permanently water and wastewater quality assessment and control with modern tools are essential in the process of water/water resources management and for health and environmental risk assessment. They will provide not only environment and human beings protection but also technological means evaluation and improvement of the environment. People should start being more responsible to this point.

It has been a more complex problem for water quality assessment. And its aim is to well and truly evaluate its degree of pollution for bodies of water, which will be easy to provide some principled projects and criterions for water resource's protection and their integration application. So, it has been widely applied into water quality assessment. SVM and directed acyclic graph support vector machine (DAGSVM) are paid much attention in this paper. A water quality assessment method based on DAGSVM is put forward. The test results show that the method proposed in this paper has an excellent performance on correct ratio. Besides, a wireless water quality monitoring system is designed and developed. The system can realize the acquisition of the water parameters, and the acquisition information timely and low cost transmission by GPRS (general packet radio service, GPRS). The developed system can store and display the water quality parameters from the monitoring spots in real time. Combining the wireless communication technology with the monitoring technology, the designed and developed system can greatly improve the real-time and continuity for the water quality's monitoring and assessment.

The reproductive behaviour of 248 specimens comprising four size classes of the infaunal bivalve Abra alba (Wood) was investigated between September 1994 and November 1995 in Kinsale Harbour. Small males returned a very small proportion of sexually mature and spawning animals. By contrast, no spawning females were found in this size class, suggesting that males develop and mature at a smaller size than females. Mean gonad maturity indices indicated that, except for the smallest size class, A. alba exhibits two spawning events in 1 year, i.e. a lesser spring and a major autumn spawning event. The spring event was well synchronised between males and females, while the autumn spawning was more broadly synchronised between the sexes. Only one spawning event was recorded for very large males and females, also occurring in spring. Spawning stages were recorded for both sexes over all size classes between February and November, indicating only a short period of sexual repose, if any. Oocyte diameters did not show a discrete size range from developing to spawning stages. All stages were seen to contain varying proportions of smaller, less mature oocytes, suggesting that large A. alba females do not develop and spawn en bloc, but release their gametes periodically. Maturity indices showed only a broad similarity with off-bottom temperatures.

Ndumo Game Reserve (NGR), a Ramsar site, situated in South Africa’s largest floodplain (Phongolo River floodplain) in northern KwaZulu-Natal, with important aquatic ecosystems: the Usuthu and Phongolo rivers and their associated floodplain lakes. While the Phongolo River is regulated, the Usuthu River is unregulated and subjected to fewer anthropogenic activities that influence the downstream environmental quality of this Ramsar system. The present study evaluates the environmental quality of floodplain systems in the NGR. Water and sediment were sampled and analysed from both rivers and associated floodplain lakes during different hydrological periods (flow). Using multivariate statistical techniques, ionic compositions, as well as water and sediment quality indices of the ecosystems were evaluated. Key findings suggest spatial and flow-related differences, which highlight the human-driven impacts from the upper catchments and the rivers influence on their respective floodplain lakes. The environmental quality (water and sediments) could be classified as ‘good’ and predominantly unimpacted. Notably, ionic composition of river water showed the importance of the unregulated Usuthu River and its contribution to aquatic ecosystems within the NGR and their continued functioning. The quality indices further indicated that metals do not currently pose any ecological risks to these systems.

Drinking water quality has become a serious issue in many countries due to the scarcity of fresh water resources. Water quality monitoring is the first step for the management and conservation of aquatic system. The contamination of OrganoChlorine Pesticides (OCPs) is very harmful for the environment and human beings. The presence of OCPs in surface water and in the bottom sediment in the Chalakudy River was investigated to evaluate the pollution load and distribution level of OCP seasonally over a period of 3 years from January 2013 to December 2015. Surface water sample and bottom sediment were collected from nine different sites (upstream, midstream and downstream) and analyzed for their profile of important physicochemical parameters and for persistence of OCP. To know the present trends in the river clearly ,temporal distribution and spatial distribution of OCPs and other parameters are studied based on three season(winter, summer, and monsoon).Obtained trend in each year were compared through sampling and analysis.