Comprehensive marine substrate classification applied to Canada’s Pacific shelf

Maps of bottom type are essential to the management of marine resources and biodiversity because of their foundational role in characterizing species’ habitats. They are also urgently needed as countries work to define marine protected areas. Current approaches are time consuming, focus largely on grain size, and tend to overlook shallow waters. Our random forest classification of almost 200,000 observations of bottom type is a timely alternative, providing maps of coastal substrate at a combination of resolution and extents not previously achieved. We correlated the observations with depth, depth-derivatives, and estimates of energy to predict marine substrate at 100 m resolution for Canada’s Pacific shelf, a study area of over 135,000 km2. We built five regional models with the same data at 20 m resolution. In addition to standard tests of model fit, we used three independent data sets to test model predictions. We also tested for regional, depth, and resolution effects. We guided our analysis by asking: 1) does weighting for prevalence improve model predictions? 2) does model resolution influence model performance? And 3) is model performance influenced by depth? All our models fit the build data well with true skill statistic (TSS) scores ranging from 0.56 to 0.64. Weighting models with class prevalence improved fit and the correspondence with known spatial features. Class-based metrics showed differences across both resolutions and spatial regions, indicating non-stationarity across these spatial categories. Predictive power was lower (TSS from 0.10 to 0.36) based on independent data evaluation. Model performance was also a function of depth and resolution, illustrating the challenge of accurately representing heterogeneity. Our work shows the value of regional analyses to assessing model stationarity and how independent data evaluation and the use of error metrics can improve understanding of model performance and sampling bias.

Effects of habitat on reef fishes biodiversity and composition in rocky reefs

Reef fish are highly valuable to human society—socially, nutritionally and economically. However, they are vulnerable to both overfishing and habitat degradation. Understanding the community structure and habitat associations of reef fish is important for their management and conservation. Using a gillnet survey conducted in a subtropical rocky reef area of Ma’an Archipelago, China, we developed habitat models linking reef fish diversity and community composition with habitat factors. The parsimonious generalized additive model results showed that higher reef fish diversity was associated with southern shallower water, temperature of 25°C, lower levels of dissolved oxygen and chlorophyll a, and rock bottom type. The multivariate generalized linear model identified that month, depth, bottom type, and location significantly influenced the local reef fish; these habitat variables explained 18% of the variation in reef fish community composition. However, the lack of strong patterns and correlations between species derived from the joint species distribution model revealed that reefs within our study area are difficult to classify based on habitat-driven patterns in their associated reef fish assemblages. These findings enhance our understanding of the habitat effects on reef fish diversity and community composition and have relevance for the management of reef fish, including habitat zonation and deployment of artificial reefs.

Ecological distribution and expansion of the polychaete genus Pholoein the southern region of the Barents Sea.

This research is centered around the influence of depth, salinity and bottom type on the polychaete genus Pholoe. Four species of the genus were identified in the southern region of the Barents Sea based on the reviewed morphological descriptions –Ph. assimilis, Ph. baltica,Ph. longa andPh. minuta. Pholoeprefer to live predominantly in shallow marine (salinity > 33.5 ‰) water on a soft bottom. In addition, depth was determined as the main limiting factor of the Pholoedistribution. However, Ph. baltica andPh. minuta were discovered to inhabit territories in a wider range of abiotic factors.

PENERAPAN TEKNOLOGI HIDROAKUSTIK DI BIDANG ILMU DAN TEKNOLOGI KELAUTAN

APPLICATION OF FIELD HYDROACOUSTIC TECHNOLOGY FOR MARINE SCIENCE AND TECHNOLOGY Utilization hydroacoustic methods in recent years have become increasingly effective for estimating the abundance of marine fish, especially fish stocks, where is impossible to do with conventional methods approach. Widely hydroacoustic technology has been used to map and classify the content of the resource base of waters and benthic animals that are on the bottom, type of substrate and benthic biota. Target Strength (TS) is the most important factor in the detection and prediction of fish stocks by using hydroacoustic. The TS is a measure that can describe the ability of a target to reflect sound waves that come about it. In the propagation of sound waves, the amount of energy per second will be flowing through the unit certain area perpendicular to the direction of propagation. The amount of energy per second crossing a certain area of the unit refers to as the intensity of the wave. The system of detection and measurement of underwater involves three components, namely medium, targets, and equipment. Sonar equation is built based on the similarity or balance between the parts of the received signal, the desired (called signal) and the unwanted parts (referred noise or noise), depending on the specific sonar functions are applied.

Kondisi Lingkungan Perairan Pada Lahan Budidaya Rumput Laut Kappaphycus alvarezii Di Desa Jayakarsa Kabupaten Minahasa Utara

A research had been conducted to evaluate seaweed and waters condition at seaweed culture area at Jayakarsa Village. Research locations were divided into three station: 1) at former culture area near mangrove area and the beach, 2) at active culture area, 3) at former culture area with sandy bottom and ”lamun” field. Water quality measured included temperature, salinity, pH, DO, turbidity, flow rate, water depth, bottom type. Protectivenss, risk, and accesibility were also observed. Data was analyzed descriptively and then compared to standard value established in Kangkan (2006). Water condition at station 1 and 2 was categorized Grade 2 (moderately suitable) while at station 3 was marginally suitable which was categorized Grade 3. Major problems faced by the farmers was ice-ice disease, silt and epiphytes that could reduce the production. Keywords: Kappaphycus alvarezii, water quality, Jayakarsa Village, moderately suitable, marginally suitable