Gastropod Communities Research Articles

Rapid declines in freshwater gastropods in Pune city, India

ABSTRACT We studied freshwater gastropod fauna in a heavily urbanized region in tropical India, across a range of habitat types. A total of 16 species were found from a two-year survey, which is a decline of 27% compared to studies completed in the 1970s. Planorbidae was the most species rich family in the collection, with five species. Racesina luteola (Lamarck, 1822) was the most commonly occurring species in the collection. Three non-native species, including Pomacea diffusa (Blume, 1957), are also reported. Habitat type influenced species occurrences, although lentic and lotic habitats were largely similar in their fauna. Many species reported previously were missing from the current survey, along with an increased incidence of non-native species which were absent from earlier reports. This decline in species richness, particularly of native species, alongside an increased incidence and spread of non-native species in the region, highlights the impact of urbanization on the freshwater gastropod community.

Existing Conditions of Gastropod Communities in Areas Affected by Nickel Mining Overburden in the Mangrove Ecosystem of Dawi-Dawi, Southeast Sulawesi

ARTICLE HIGLIGHTS- Nickel mining activities significantly impacted the ecological integrity of the Pomalaa coastal area in Southeast Sulawesi, particularly in the mangrove ecosystem.- The exposure of overburden waste in the mangrove ecosystem has led to the loss of important gastropod species and a decline in population of surviving species- The low population of gastropod species in nickel mining impact areas indicates extensive environmental damage caused by these activities.ABSTRACTGastropod resources in the Dawi-Dawi mangrove ecosystem, Southeast Sulawesi are greatly influenced by the input of overburden waste (sediment) from nickel mining activities. This condition has been going on for the last 2 decades and has degraded the habitat and structure of the gastropod community. The upstream connectivity (the existing nickel mining area) and the Dawi-Dawi River estuary mean that the mangrove forest (estuary) in this area is continuously affected by (massive) overburden runoff. This research was carried out in June-August in the mangrove ecosystem of Dawi-Dawi Village, Southeast Sulawesi Province. This research aims to determine the existing condition of mangrove gastropods affected by overburden. This research began by conducting initial observations in the field, to identify mangrove ecosystems affected by overburden. research stations were determined using a purposive sampling technique (targeted) and sampling gastropods using a simple random sampling method. The ecological index of the mangrove gastropod community affected by overburden shows a tendency for a medium diversity index (H'=1.81), low species richness (R=1.42), high evenness (E=1.12), and no dominance of certain species (C=0.19). The gastropod species found are typical types that make up the mangrove fauna, namely Terebralia sulcata, Terebralia palustris, Faunus ater, Telescopium telescopium, Hebra nigra, and several taxa (genus) of climbing Littoraria snails (periwinkle) which are found in the roots, stems and leaves of mangroves. The abundance of gastropods obtained was also very low, namely around 0-12 Ind./m2. At some points (rarely) schools of small snails of the type T. sulcata (5-21 Ind./m2) are sometimes found. This research shows de facto that overburden waste eliminates (survival) or reduces the diversity and richness of gastropod species (ecological index) in the mangrove ecosystem of Dawi-Dawi.

Tropical gastropod density and diversity in the mangrove forest of Totobo Village, Southeast Sulawesi, Indonesia

Abstract. Purnama MF, Prayitno SB, Muskananfola MR, Suryanti. 2024. Tropical gastropod density and diversity in the mangrove forest of Totobo Village, Southeast Sulawesi, Indonesia. Biodiversitas 25: 1663-1675. The mangrove ecosystem of Totobo Village, Southeast Sulawesi, is a habitat for various species of edible and economically important gastropods. This research aims to determine mangrove gastropods' density and ecological index (diversity). This research was carried out from June to September 2023 in the mangrove ecosystem of Totobo. This research adopts purposive sampling and systematic random sampling techniques to determine stations and place the distribution of sampling points (sub-stations). The gastropod sample collection was done using the handpicking method or manually. More than 34 species of gastropods (14 families and 24 genera) were found in the mangrove ecosystem of Totobo. The diversity index (H' = 3.07) of gastropods in the Totobo mangrove ecosystem is directly proportional to the species richness value (R = 4.43), which is in the high category. The evenness index is in the medium category (E = 0.89), and the dominance index (C) has a value of 0.01, meaning no dominance of a particular species. The condition described is a representation of a system of homeostasis or environmental balance that is currently being maintained. This directly impacts the optimal biological activity (physiology) of the gastropod community and other aquatic organisms in the mangrove ecosystem (estuary) of Totobo Village.

No effects of macroconsumer exclusion on macroinvertebrate functional composition in Brazilian karst streams along a gradient of riparian forest loss

AbstractDegradation and loss of riparian vegetation are some of the main drivers of change in the trophic interactions among aquatic macroconsumers. These changes can often have major consequences for biodiversity and stream ecosystem functioning. Yet, many aspects of food‐web dynamics are still not well understood, including how food webs among tropical streams respond to riparian vegetation loss. We examined the role of macroconsumers on community structure of functional feeding groups of benthic macroinvertebrates along a forest cover gradient within the Bodoquena Plateau, Brazil. We compared the effect of excluding macroconsumers (using electric fences) on functional feeding groups to those in controls within seven karst streams along a gradient of riparian vegetation cover. Aquatic insect and gastropod communities were dominated by groups of collector‐gatherers, scrapers, and predators across all sites. The exclusion of macroconsumers did not lead to an increase in the abundance of macroinvertebrates and was not affected by the forest cover during the experiment. These findings demonstrated that the experimental exclusion of macroconsumers resulted in a lack of or negligible effect on functional feeding groups along the gradient of forest cover. It is important to consider the specificity of trophic relationships to fully understand the effects of vegetation loss on streams where complex groundwater hydrology can also affect food webs such as in karst terrain.Abstract in Portuguese is available with online material.

The Community Structure of Gastropods (Mollusca Phylum) in The Intertidal Zone of Saung Beach, Wakan Village, Jerowaru District, East Lombok Regency

Gastropods are one of the phylum Mollusca classes having a single shell, normally spiral-shaped. This research aimed to analyze the Gastropod community structure (Mollusca Phylum) in the Intertidal Zone of Wakan Village, Jerowaru District, East Lombok Regency. The combination of line and quadrat transect was implemented to take samples in this study. The variables in the research include the type and quantity of Gastropods. There were 1.715 individual of Gastropod found in this study. They were included in 11 families and 17 species. The Gastropod species with the highest abundance value in station I and II was Strombus urceus with the abundance value of 12,8 ind/m2 and 5,72 ind/m2, respectively. Meanwhile, in station III, it was Terebralia sulcate with the abundance value of 3,4 ind/m2. The diversity index of Gastropods in the research location was categorized as medium (H’=2,32) with a stable divercity index (E=0,84) and a low domination index (C=0,14).

Gastropoda community structure in the mangrove forest of Ketapang Coastal Waters, Rupat District

Gastropod community structure is a concept or study that studies the arrangement or composition of species in an ecosystem. Changes influence the structure of this gastropod community in terms of environmental factors such as temperature, salinity, substrate type, and organic matter content. Rupat District is geographically located in a cluster of islands directly adjacent to the Strait of Malacca, strongly influenced by coastal environmental conditions. Rupat sub-district has one of three tropical marine ecosystems, namely mangroves. This study aims to determine the structure of gastropod communities in mangrove forests in Ketapang Beach, Rupat District waters. The study was conducted in April 2023 using the technique of random sampling with a total of three stations. There are 8 (eight) species of gastropods found, with the species Cerithidea obtusa the dominant one. The abundance of gastropods is 130,000 ind/ha. The value of the diversity index (H') is 1.24, the uniformity index (E) is 0.33, and the dominance index value (C) is 0.40. The distribution pattern (Id) is grouping. The similarity index (Ss) of gastropods between each station in Ketapang Beach is almost the same type and has similarities that are classified as high category. Test results Oneway ANOVA < 0.05. The LSD (Least Significance Difference) test states that the abundance between stations I and III is significant, just as stations II and III are markedly different. The abundance between station I and station II does not differ markedly.

KEANEKARAGAMAN GASTROPODA DI PADANG LAMUN PERAIRAN PANTAI DESA RUTONG

Background: Gastropods are included in the mollusk phylum which is one of the non-fish biological resources that has quite high biodiversity. The gastropod community is an important component in the food chain in seagrass beds, where gastropods are detritus feeders. Methods: This research was conducted in seagrass beds in the waters of Rutong Village Beach in June-July 2022, using the quadrant linear transect method. The distance between transects is 25 meters with a total of 5 transect lines, each transect line has 10 plots and the distance between plots is 10 meters. Diversity of gastropods using index index formula, Evenness and Richness. Results: The results of measurements of environmental factors, namely temperature 29; pH 7.8; Salinity 34‰; DO 7.9 μg/l; Gastropod research results obtained 987 individuals consisting of 10 orders, 18 families, 22 general and 34 species. The index value of Diversity (H') is 1,394, the evenness index (E) is 0,395, and the wealth index is 4,786. Conclusion: Environmental factors in the seagrass bed of the coastal waters of Rutong Village are good for sustaining the life of gastropods; The types of gastropods found were 34 species; The Diversity Index (H') is moderate, the Evenness Index (E is low, and the Wealth Index (DMg) is moderate

Effects of environmental impacts on the distribution and morphometric characteristics of Rehderiella parva (Lea, 1856) (Gastropoda: Hydrobiidae) and the gastropod communities of the Chao Phraya River (Thailand )

Effects of environmental impacts on the distribution and morphometric characteristics of Rehderiella parva (Lea, 1856) (Gastropoda: Hydrobiidae) and the gastropod communities of the Chao Phraya River (Thailand )

Gastropod Community Structure in the Mangrove Area, Kuala Batee District, Southwest Aceh District

This research was conducted to determine the types of gastropods and the structure of the gastropod community in the Mangrove area of Kuala Batee District, Southwest Aceh Regency. The quantitative descriptive method is used to determine research stations using purposive sampling techniques. Gastropod sampling was carried out at three station locations, each station consisting of three sub-stations with a size of 10 x 10 m. In the substations, 15 transects measured 1 x 1 m, namely, two points at the corner of each transect and one point in the middle. The results of the research showed that the gastropods found were 11 species from 4 ordo, ordo Archaeogastropoda consists of Neritina turita, N.semiconica, N.variegate, Neritodryas dubia, and Clithon corona, ordo Ceanogastropoda consists of Faunus ater and Bitium munitum, ordo Mesogastropoda consists of Cerithidea optusa, Stenomelania plicaria, and Thiara scabra, ordo Ellobiida consist of Cassidula angulifera. The structure of the gastropod community in the mangrove area of Kuala Batee District, Southwest Aceh Regency, has a diversity index ranging from 0.65-1.32, including the medium category, uniformity index values ranging from 0.36-0.63 including the medium category, and dominance values ranging from between 0.33-0.63 is included in the medium category. Environmental parameters in the mangrove area show an average temperature value of 28.20C, a salinity value of 5.6 ppt, and a pH value of 8.3

Diversity and density of marine intertidal gastropods in tropical seagrass beds at Oransbari Bay, South Manokwari - West Papua

Gastropod communities are one of the important components of the food chain in seagrass meadows. This study aims to investigate the diversity of gastropods in the distribution of the seagrass beds at Oransbari Bay. This study was carried out in November 2022, using the line transect method. Data collection is carried out at three stations, where each station is divided into three transects. A total of 36 species consisting of 16 families and 5 orders, were recorded in this study. The total density of gastropods found in the waters of Oransbari Bay ranged from 5.77-9.43 ind/m2, with an average of 6.99 ± 2.10 ind/m2. Conus sp. has the highest density value of any gastropod. Meanwhile, for seagrasses, five species from four clans and two families were obtained. The percent cover of seagrass ranges from 17.05 ± 3.30% – 58.90 ± 22.90% with an average of 40.18 ± 21.3%. Halophila minor and Thallasia hempricii showed a positive correlation with gastropod density. The value of the gastropod diversity index is in the medium category, the gastropod evenness index is in the stable category, and the gastropod dominance index is in the low category. The results of this study provide a base for a proper gastropod checklist at Oransbari Bay. Future research is recommended that involves a more detailed studies on the feeding ecology and habitat preference of the gastropods.Keywords:DiversityDistributionGastropodsSeagrass bedsOransbari bay

Study of Gastropod Community Structure After Development of Tourism Activities on the Senjoyo River

It is thought that the development of the Senjoyo River as a tourist attraction in Semarang Regency will cause changes to the natural ecosystem in the area, one of which is changing the structure of the existing gastropod community. This research is a quantitative analysis research using a survey method that aims to examine the structure of the gastropod community after the development of tourism activities on the Senjoyo River. Gastropod samples were taken from 10 different observation stations along the Senjoyo River, which are located at 7˚22'23"S and 110˚31'37"E. Observation station locations were determined by the purposive random sampling method, based on tourism activity density. The result showed types of gastropods that were found in the Senjoyo River namely, Sulcospira testudinaria, Tarebia granifera, Brotia costula, Thiara scraba, and Melanoides tuberculata with clustered distribution patterns (Id>1). Statistical analysis showed that location affected gastropod abundance (Asymp. Sig of 0.043), with the highest abundance found at station seven (45,11 individuals/m2). So station seven, with sandy and muddy substrate conditions, moderate current speed (0.257 m/s), and rarely found human activity, is the most suitable location to support the survival of gastropods in the Senjoyo River. Furthermore, the gastropod community structure indicates environmental changes at observation stations nine and ten, the locations where the most activities and construction of tourism facilities were found. That was indicated by the low diversity (H’= 0.00-0.01) and evenness (E = 0.00) index of gastropods, and there is dominance by Sulcospira testudinaria (C= 0.98-1.00).

Gastropod community structure in the water of Terkulai Island Tanjungpinang City

Gastropods are marine biota found in the waters of Pulau Terkulai, Tanjungpinang City and are one of the catch of fishermen. However, information on the structure of the gastropod community in these waters is not widely known. The purpose of this study was to determine the types of gastropods, gastropod community structure, and the relationship between gastropod community structure and environmental parameters in the waters of Terkulai Island. This research was conducted in April-August 2023. Determination of sampling points using random sampling method as many as 30 points with sampling plots measuring 1x1m2. The results of this study obtained 650 individuals with 15 species of gastropods. The highest density was found in Batillaria attramentaria species with a total of 12.20 ind/m2. Gastropod community structure diversity value (H') ranged from 1.512 which is classified as moderate. The uniformity value (E) ranges from 0.558 which is classified as moderate and the dominance value (D) ranges from 0.353 which is classified as moderate. The results of the measurement of the physicochemical parameters of the waters are still at a feasible threshold for gastropod life. The principal component analysis (PCA) shows that the density with water parameters has a positive correlation with temperature and organic matter.

Consumer Informatics and One Health: Shifting the Focus from the Individual to the Globe. Findings from the Yearbook 2023 Section on Education and Consumer Health Informatics.

To summarise the state of the art during the year 2022 in consumer health informatics and education, with a special emphasis on "One Health". We conducted a systematic search of articles published in PubMed. We build queries to merge terms related to "consumer health informatics", "one health", and "digital". We retrieved 94 potential articles for review. These articles were screened according to topic relevance and 12 were selected for consideration of best paper candidates, which were then presented to a panel of international experts for full paper review and scoring. The top five papers were discussed in a consensus meeting. Three papers received the highest score from the expert panel, and these papers were selected to be representative papers on consumer informatics for exploring one health from consumer perspective in the year 2022. Bibliometrics analysis conducted on words found in abstracts of the 12 candidate papers revealed four clusters of articles, where clustering outcomes explained 96.91% of the dispersion. The first cluster composes three papers related to patient engagement in primary care practices, using digital-delivered diabetes prevention programmes, or exploring citizen involvement in co-designing environmental projects (such as air pollution exposure and health). The second cluster represents four papers related to digital health literacy and consumer behavior, such as digital vaccine literacy, and food labelling influences and whether displaying Nutri- and Eco-Score at food product level led to improved consumer choices. The third cluster consists of two papers exploring strategies to involve citizens in various science projects while analyzing the quality of citizen-collected data (e.g., mosquito bites or gastropod community dataset). The last cluster contains three papers related to the relationships between human behavior with their environment and their contribution to citizen science projects (e.g., biological water quality in the Netherlands distribution, composition, abundance of debris across sandy beaches in Australia and its regions, urbanization and reptile biodiversity across Florida). Traditionally, consumer health informatics focuses on providing individuals with tools and resources to actively manage their own health. By incorporating a global health (or one health) perspective, our field is now at a crossroad, demanding us to think beyond the individual and challenging us to instill the thinking that our actions not only have consequences on the individual but also on the population and the environment. Perhaps this is also a reflective time for the consumer informatics field, to consider shifting the focus from the individual to one that is more aligned with one health, helping consumers gain awareness of how their actions impact on the individual, the population and the environment, and providing them with tools to work collectively to help decide how their actions may bring benefits (as well as harms) across these levels.

Gastropod community structure on seagrass beds in Bahoi Village, North Minahasa

The village of Bahoi has a vast expanse of seagrass meadows of approximately 16.50 Ha, located between mangrove and coral reef ecosystems. This study aims to inventory the gastropod species in the seagrass meadow of Bahoi village waters and to determine the gastropod community structure through analysis of species density, relative density, species diversity index, and dominance index. The method used was a transect line method along 50 meters and a 1x1m quadrat pulled towards the sea, repeated three times during low tide. A total of 117 individuals were found, belonging to 26 species (11 families and 17 genera) of gastropods in the seagrass meadow of Bahoi village coastal waters. Based on the results, the highest density value was 1.10 ind/m2 with a relative density of 28.20%. Based on the analysis, the dominance index (D) of gastropods in the seagrass meadow of Bahoi village coastal waters was low, with values of D = 0.019 to 0.041, indicating that there was no specific species dominance in the seagrass meadow of Bahoi village coastal waters. This has an effect on the diversity index with a value of H' = 2.51, which is categorized as moderate. These results show that the diversity of gastropod species in the seagrass meadow of Bahoi village waters is quite diverse due to the absence of specific gastropod species dominance.
 Keywords: Bahoi, Seagrass Meadow, Gastropods, Community Structure.
 Abstrak
 
 Desa Bahoi memiliki luas hamparan padang lamun ± 16.50 Ha yang berada di antara ekosistem mangrove dan ekosistem terumbu karang. Penelitian ini bertujuan untuk melakukan inventarisasi jenis-jenis gastropoda di hamparan lamun perairan Desa Bahoi, dan mengetahui struktur komunitas gastropoda melalui analisis kepadatan spesies, kepadatan relatif, indeks keanekaragaman spesies, dan indeks dominasi. Metode yang digunakan adalah metode transek garis sepanjang 50 meter dan kuadrat berukuran 1×1m yang ditarik ke arah laut, dan dilakukan ulangan sebanyak 3 kali pada saat air surut.Ditemukan 117 individu yang termasuk ke dalam 26 spesies (11 famili dan 17 genera) gastropoda di hamparan padang lamun perairan pantai desa Bahoi. Berdasarkan hasil penelitian, nilai kepadatan tertinggi sebesar 1,10 ind/m2 dengan kepadatan relatif 28,20%. Berdasarkan hasil analisis, Indeks Dominansi (D) gastropoda di hamparan lamun perairan pantai desa Bahoi tergolong rendah, dengan nilai D=0,019 sampai dengan 0,041 menunjukkan bahwa tidak terdapat dominasi spesies tertentu di hamparan padang lamun perairan pantai desa Bahoi. Hal ini berpengaruh terhadap Indeks Keanekaragaman dengan nilai H’=2,51 sehingga berada pada kategori sedang. Hasil tersebut menunjukkan bahwa keanekaragaman jenis gastropoda di hamparan lamun perairan pantai desa Bahoi cukup beragam dikarenakan tidak adanya dominasi spesies gastropoda tertentu.
 Kata kunci: Bahoi, Padang Lamun, Gastropoda, Struktur Komunitas

GASTROPOD COMMUNITY STRUCTURE IN THE INTERTIDAL ZONE OF PASUMPAHAN ISLAND, PADANG CITY, WEST SUMATRA PROVINCE

Pasumpahan Island is one of the islands located in West Sumatra Province which has various activities of daily life, especially in the intertidal zone; it is suspected that it can interfere with the existence of aquatic organisms one of which is gastropods. Studying the structure of gastropod communities in the intertidal zone is an interesting natural laboratory to study. This research was conducted from December 2021 to January 2022 on Pasumpahan Island Padang City West Sumatra Province. The purpose of this study was to determine the structure of the gastropod community which includes species, abundance, diversity, uniformity, dominance, and distribution pattern of gastropods. As supporting data in this study, several environmental parameters were also measured which included water quality, sediment type, and sediment organic matter content. The research method used is a survey method, where sampling using the quadrat transect method is carried out at 3 stations. Based on the results of the study found 13 species of gastropods. The most common species found at all stations was Pythia scarabaeus, where the gastropod abundance values obtained between stations ranged from 2,78 to 5,00 ind/m2. The value of the species diversity index ranged from 1,50 to 2,02, which was moderate, the uniformity index value ranged from 0,77 to 0,88, which was high uniformity, and the dominance index value ranged from 0,16 to 0,29, meaning that there were no species found dominates and the value of the distribution pattern ranges from 1,31 to 2,47 with a clustered distribution pattern

The “Minor Water Bodies” and Their Malacofauna: Are Freshwater Gastropod Communities Usable for Habitat Classification?

The typology of inland water bodies remains a topical issue in limnology. Numerous classifications of freshwater habitats have been proposed, but none of them has gained the universal acceptance. Current global changes and the increasing human impact on freshwater ecosystems make it important to understand the ecological relationships between freshwater animals and their environment. In this study, we tested a typology of the so-called “minor water bodies” proposed in the 1960s by the Polish ecologist Klimowicz. The term “minor water bodies” refers to a group of semi- or impermanent habitats that are prone to periodical or occasional desiccation. The division of habitat categories within this typology was based on qualitative features, and the validity of this classification has never been tested statistically. Here, we used the data on occurrences of 18 species of freshwater and semiaquatic gastropods observed in 86 minor water bodies of the Bolshoy Yugan River basin (Western Siberia, Russia) to test the hypothesis that each type of minor water body, in accordance with the aforementioned classification, maintains its own unique set of species. The statistical analysis confirmed the significant differences between the three habitat types on the basis of their gastropod communities, whereas one type (groundwater springs) appeared to be indistinguishable from the others. Our results show that freshwater gastropod communities are a suitable tool for habitat classification, and, at the same time, they highlight the need to apply statistical methods to a priori classifications based on the qualitative approach to the division of habitat types.

Bioaccumulation and ecotoxicological impact of micro(nano)plastics in aquatic and land snails: Historical review, current research and emerging trends.

Microplastics (MPs) and nanoplastics (NPs) are ubiquitous emerging pollutants in the environment. Although MPs/NPs' hazardous effects have been described at different trophic levels, little attention has been given to how they can affect gastropod communities. Thus, the current study aimed to summarize and critically address data available in the scientific literature about micro(nano)plastics' ecotoxicological impact on snails. The analyzed data has evidenced MP/NP bioaccumulation in 40 gastropod species collected in the field; 15 gastropod species were used to assess the potential toxicity of MPs/NPs. Asia accounted for the highest level of MPs/NPs bioaccumulated in gastropods; it was followed by the South American, European and Antarctic continents. MPs/NPs' toxicity depends on their composition, shape and size, as well as on differences in methodological approaches adopted by different studies. Results have shown that MPs/NPs induce several impairments - such as behavioral changes, developmental toxicity, dysbiosis, histopathological alterations, oxidative stress -, generate ecological impairments, as well as act as pollutant vector and increase chiral chemicals' toxicity. Research gaps and recommendations for future research were highlighted to help better understanding MPs/NPs' toxicity in gastropods, given the extremely important role played by them in studies focused on investigating how MPs/NPs can affect invertebrate communities living in terrestrial and aquatic environments.

Multi-indicator ‘state space’ approach to assessing changes in shallow urban reef ecosystem health

Tracking changes in ecosystem health is an important objective for environmental managers, but is often limited by an understanding of what constitutes a “healthy” system and how to aggregate a range of health indicators into a single meaningful metric. We used a multi-indicator ‘state space’ approach to quantify changes over 13 years in reef ecosystem health in an urban area that has undergone intense housing development. Based on nine health indicators (macroalgal canopy length and biomass, macroalgal canopy and habitat functional diversity, mobile and predatory invertebrate density and size, total species and non-indigenous species richness), we found that the overall health of the reef community declined at five of the ten study sites. This decline was associated with a large collapse in the gastropod community, a shortening of macroalgal canopies and an increase in the number of non-indigenous species. While the cause of this decline and mechanisms responsible are not fully understood, the decline correlated with an increase in sediment cover on the reefs and warming ocean temperatures over the monitoring period. The proposed approach provides an objective and multifaceted quantitative assessment of ecosystem health that can be easily interpreted and communicated. These methods could be adapted to other ecosystem types to inform management decisions regarding future monitoring, conservation and restoration priorities to achieve greater ecosystem health.

Gastropod Microhabitat Associations and Niches in Seagrass Ecosystems on Donrotu Island, South Jailolo District, West Halmahera Regency

Gastropods are included in the mollusk phylum which is known to be well-associated with seagrass ecosystems. The gastropod community is an important component in the food chain in seagrass beds and ecologically seagrass beds have an important role in the ecosystem. Seagrass ecosystems are habitats and food sources for fish and other aquatic biota. One of the biota commonly found in seagrass beds is Gastropods. This study was conducted to know the composition of gastropod species, types of gastropod associations, and gastropod microhabitat niches in seagrass ecosystems on Donrotu Island. Gastropod sampling was carried out at low tide. The gastropod samples found were then put into a plastic bag that already contained a label. Furthermore, the gastropod samples were brought ashore to count the number of individuals of each type and determined based on morphological characteristics such as shell shape, shell color, shell mouth opening, and spiral circle based on Dharma (1992) instructions. Based on the results of the study, the composition of the types of gastropods found in the seagrass ecosystem on the island of Donrotu was as many as 13 species. There were 13 pairs of gastropod types that had positive associations and 65 pairs of no associations. The type of gastropod that has the widest habitat niche is Cypraea tigris and the narrowest are Naticarius coillei and Pseudovertagus aluco.

Hubungan Kerapatan Lamun dengan Kepadatan Gastropoda Pada Habitat Lamun Di Perairan Desa Tayando Yamtel Kecamatan Tayando Yamtel Kota Tual

The gastropod community is an important component in the food chain in seagrass beds, where gastropods are basic detritus feeders. The presence of gastropods is largely determined by the presence of seagrass vegetation in coastal areas. Research on the relationship between seagrass density and gasrtopod density in the waters of Tayando Yamtel Village, Tam District, Tual City, was conducted in March-May 2018, using the quadrant linear transect method. The results of the research on the relationship between seagrass density and gasrtopod density obtained a correlation value at station I, obtained a 2-tailed significance value > 0.05 indicating a sufficient/moderate degree of relationship (r = 0.441) and the direction of the relationship was positive. While at stations II (r = -0.778) and III (r = -0,308) showed a 2-tailed significance value <0.05 with a very weak degree of relationship and a negative direction of relationship.