STREAM Journal, Vol. 4, No. 1, pp 1-17. January-March 2005

CONTENTS: Young people taking bolder steps, by Josephine P. Savaris. Providing a venue for voices to be heard, by Elizabeth M. Gonzales and Josephine Savaris. Rehabilitation of Bundu Pond: STREAM’s Initiative and DoF’s Action, by Bhim Nayak and Ashish Kumar. Coastal resources utilization and conservation issues in Cox’s Bazar, Bangladesh, by M.K. Abu Hena, H. Sharifuzzaman, M.S. Aftabuddin and M.N. Haque. People, fish and reefs: a livelihoods learning curve, by Abigail Moore. Understanding the marine ornamental trade and its impact on the livelihoods of poor stakeholders in the Philippines, by Elizabeth M. Gonzales.

Characterization of the benthos, marine debris and bottom fish at Gray’s Reef National Marine Sanctuary

Executive Summary: Baseline characterization of resources is an essential part of marine protected area (MPA) management and is critical to inform adaptive management. Gray’s Reef National Marine Sanctuary (GRNMS) currently lacks adequate characterization of several key resources as identified in the 2006 Final Management Plan. The objectives of this characterization were to fulfill this need by characterizing the bottom fish, benthic features, marine debris, and the relationships among them for the different bottom types within the sanctuary: ledges, sparse live bottom, rippled sand, and flat sand. Particular attention was given to characterizing the different ledge types, their fish communities, and the marine debris associated with them given the importance of this bottom type to the sanctuary. The characterization has been divided into four sections. Section 1 provides a brief overview of the project, its relevance to sanctuary needs, methods of site selection, and general field procedures. Section 2 provides the survey methods, results, discussion, and recommendations for monitoring specific to the benthic characterization. Section 3 describes the characterization of marine debris. Section 4 is specific to the characterization of bottom fish. Field surveys were conducted during August 2004, May 2005, and August 2005. A total of 179 surveys were completed over ledge bottom (n=92), sparse live bottom (n=51), flat sand (n=20), and rippled sand (n=16). There were three components to each field survey: fish counting, benthic assessment, and quantification of marine debris. All components occurred within a 25 x 4 m belt transect. Two divers performed the transect at each survey site. One diver was responsible for identification of fish species, size, and abundance using a visual survey. The second diver was responsible for characterization of benthic features using five randomly placed 1 m2 quadrats, measuring ledge height and other benthic structures, and quantifying marine debris within the entire transect. GRNMS is composed of four main bottom types: flat sand, rippled sand, sparsely colonized live bottom, and densely colonized live bottom (ledges). Independent evaluation of the thematic accuracy of the GRNMS benthic map produced by Kendall et al. (2005) revealed high overall accuracy (93%). Most discrepancies between map and diver classification occurred during August 2004 and likely can be attributed to several factors, including actual map or diver errors, and changes in the bottom type due to physical forces. The four bottom types have distinct physical and biological characteristics. Flat and rippled sand bottom types were composed primarily of sand substrate and secondarily shell rubble. Flat sand and rippled sand bottom types were characterized by low percent cover (0-2%) of benthic organisms at all sites. Although the sand bottom types were largely devoid of epifauna, numerous burrows indicate the presence of infaunal organisms. Sparse live bottom and ledges were colonized by macroalgae and numerous invertebrates, including coral, gorgonians, sponges, and “other” benthic species (such as tunicates, anemones, and bryozoans). Ledges and sparse live bottom were similar in terms of diversity (H’) given the level of classification used here. However, percent cover of benthic species, with the exception of gorgonians, was significantly greater on ledge than on sparse live bottom. Percent biotic cover at sparse live bottom ranged from 0.7-26.3%, but was greater than 10% at only 7 out of 51 sites. Colonization on sparse live bottom is likely inhibited by shifting sands, as most sites were covered in a layer of sediment up to several centimeters thick. On ledge bottom type, percent cover ranged from 0.42-100%, with the highest percent cover at ledges in the central and south-central region of GRNMS. Biotic cover on ledges is influenced by local ledge characteristics. Cluster analysis of ledge dimensions (total height, undercut height, undercut width) resulted in three main categories of ledges, which were classified as short, medium, and tall. Median total percent cover was 97.6%, 75.1%, and 17.7% on tall, medium, and short ledges, respectively. Total percent cover and cover of macroalgae, sponges, and other organisms was significantly lower on short ledges compared to medium and tall ledges, but did not vary significantly between medium and tall ledges. Like sparse live bottom, short ledges may be susceptible to burial by sand, however the results indicate that ledge height may only be important to a certain threshold. There are likely other factors not considered here that also influence spatial distribution and community structure (e.g., small scale complexity, ocean currents, differential settlement patterns, and biological interactions). GRNMS is a popular site for recreational fishing and boating, and there has been increased concern about the accumulation of debris in the sanctuary and potential effects on sanctuary resources. Understanding the types, abundance, and distribution of debris is essential to improving debris removal and education efforts. Approximately two-thirds of all observed debris items found during the field surveys were fishing gear, and about half of the fishing related debris was monofilament fishing line. Other fishing related debris included leaders and spear gun parts, and non-gear debris included cans, bottles, and rope. The spatial distribution of debris was concentrated in the center of the sanctuary and was most frequently associated with ledges rather than at other bottom types. Several factors may contribute to this observation. Ledges are often targeted by fishermen due to the association of recreationally important fish species with this bottom type. In addition, ledges are structurally complex and are often densely colonized by biota, providing numerous places for debris to become stuck or entangled. Analysis of observed boat locations indicated that higher boat activity, which is an indication of fishing, occurs in the center of the sanctuary. On ledges, the presence and abundance of debris was significantly related to observed boat density and physiographic features including ledge height, ledge area, and percent cover. While it is likely that most fishing related debris originates from boats inside the sanctuary, preliminary investigation of ocean current data indicate that currents may influence the distribution and local retention of more mobile items. Fish communities at GRNMS are closely linked to benthic habitats. A list of species encountered, probability of occurrence, abundance, and biomass by habitat is provided. Species richness, diversity, composition, abundance, and biomass of fish all showed striking differences depending on bottom type with ledges showing the highest values of nearly all metrics. Species membership was distinctly separated by bottom type as well, although very short, sparsely colonized ledges often had a similar community composition to that of sparse live bottom. Analysis of fish communities at ledges alone indicated that species richness and total abundance of fish were positively related to total percent cover of sessile invertebrates and ledge height. Either ledge attribute was sufficient to result in high abundance or species richness of fish. Fish diversity (H`) was negatively correlated with undercut height due to schools of fish species that utilize ledge undercuts such as Pareques species. Concurrent analysis of ledge types and fish communities indicated that there are five distinct combinations of ledge type and species assemblage. These include, 1) short ledges with little or no undercut that lacked many of the undercut associated species except Urophycis earlii ; 2) tall, heavily colonized, deeply undercut ledges typically with Archosargus probatocephalus, Mycteroperca sp., and Pareques sp.; 3) tall, heavily colonized but less undercut with high occurrence of Lagodon rhomboides and Balistes capriscus; 4) short, heavily colonized ledges typically with Centropristis ocyurus, Halichoeres caudalis, and Stenotomus sp.; and 5) tall, heavily colonized, less undercut typically with Archosargus probatocephalus, Caranx crysos and Seriola sp.. Higher levels of boating activity and presumably fishing pressure did not appear to influence species composition or abundance at the community level although individual species appeared affected. These results indicate that merely knowing the basic characteristics of a ledge such as total height, undercut width, and percent cover of sessile invertebrates would allow good prediction of not only species richness and abundance of fish but also which particular fish species assemblages are likely to occur there. Comparisons with prior studies indicate some major changes in the fish community at GRNMS over the last two decades although the causes of the changes are unknown. Species of interest to recreational fishermen including Centropristis striata, Mycteroperca microlepis, and Mycteroperca phenax were examined in relation to bottom features, areas of assumed high versus low fishing pressure, and spatial dispersion. Both Mycteroperca species were found more frequently when undercut height of ledges was taller. They often were found together in small mixed species groups at ledges in the north central and southwest central regions of the sanctuary. Both had lower mode size and proportion of fish above the fishery size limit in heavily fished areas of the sanctuary (i.e. high boat density) despite the presence of better habitat in that region. Black sea bass, C. striata, occurred at 98% of the ledges surveyed and appeared to be evenly distributed throughout the sanctuary. Abundance was best explained by a positive relationship with percent cover of sessile biota but was also negatively related to presence of either Mycteroperca species. This may be due to predation by the Mycteroperca species or avoidance of sites where they are present by C. striata. Suggestions for monitoring bottom features, marine debris, and bottom fish at GRNMS are provided at the end of each chapter. The present assessment has established quantitative baseline characteristics of many of the key resources and use issues at GRNMS. The methods can be used as a model for future assessments to track the trajectory of GRNMS resources. Belt transects are ideally suited to providing efficient and quantitative assessment of bottom features, debris, and fish at GRNMS. The limited visibility, sensitivity of sessile biota, and linear nature of ledge habitats greatly diminish the utility of other sampling techniques. Ledges should receive the bulk of future characterization effort due to their importance to the sanctuary and high variability in physical structure, benthic composition, and fish assemblages. (PDF contains 107 pages.)

Cruises of the Albatross off San Diego and Other Parts of Southern California, 1889–1916

Between 1889 and 1916, the U. S. Fish Commission steamer Albatross made numerous trips to waters off southern California, particularly in and near San Diego Bay. The typical pattern for many years was to conduct cruises in waters off the Pacific Northwest or Alaska in summer months and waters off southern California in winter months. The Albatross conducted the first depth soundings and benthic profiles for southern California waters and secured the first samples of many endemic marine animals of this region. Albatross collections formed the basis for numerous definitive monographs of invertebrates and vertebrates that were published in subsequent years. The Albatross anchored in San Diego Bay in 1894, conducting the first biological investigations of the bay, and returned to sample again in many subsequent years. The ship and its crew also examined Cortez and Tanner banks for exploitation potential and conducted the first biological investigations of southern California’s tuna stocks in 1915 and 1916.

Seasonal variation of mixed layer depth in the north Arabian Sea

The Arabian Sea is unique due to the extremes in atmospheric forcing that lead to the semi-annual seasonal changes. The reversing winds of summer and winter monsoon induce the variation in the characteristics of mixed layer depth. The importance of mixed layer depth is recognized in studying the biological productivity in the ocean. In this paper variability of mixed layer depth in the north Arabian Sea have been discussed. The study is based on the data collected under North Arabian Sea Environment and Ecosystem Research (NASEER) program. The results of the study indicate that there is a significant variation in the mixed layer depth from summer to winter monsoon as well as coast to offshore.

Pathology of mixed infections of saprolegniasis-myxosporidiosis in Indian major carp (Catla catla Ham.)

An outbreak of saprolegniasis in Catla catla in composite carp culture ponds were recorded during winter season. The typical cotton wool growths were observed on whole body surfaces of catla along with sporadic mortality. The fungal invasion was only restricted to skin and no fungal elements were visible in any internal organs after periodic acid schiff staining. On histology, periportal accumulation of mononuclear cells in liver, presence of myxosporidean cysts in antieror kidney, eosinophilic granular cells reaction in submucosa of stomach and intestine, dilated and engorged blood vessels of brain along with sloughing of epidermis and hyperplasia at gill lamellar base were pronounced changes. The possible role of release of Saprolegnia toxin in producing internal organs pathology has been discussed.

Effect of mixed feeding schedule on growth and nutrient utilisation in Rohu, Labeo rohita (Ham.) fingerlings

Studies on nutrient utilisation and growth of rohu (Labeo rohita) fingerlings (3.13-4.09 g) raised on seven feeding schedules under laboratory conditions (26.3-33.5°C) showed that two days regular feeding on Diet B (high protein, 38.90%) resulted in maximum growth and protein retention efficiency. While regular feeding on low protein diet (Diet A) resulted in poor nutrient utilisation and growth of fish, high protein diet (Diet B) did not show any significant difference in growth from the mixed 2A-3B schedules but exhibited comparatively low protein retention efficiency. The other feeding schedules were 1A-2B, 1A-3B, 2A-2B and 2A-4B, where the numerical value refers to the number of days for continuous feeding of a particular diet. The diets A and B served as the controls which contained 3.40 and 3.67 kcal/g gross energy respectively. The 2A-3B feeding schedule was also found to be highly economic as an expenditure of Rs.11/- only was required for raising the body weight by one kilo as against Rs.17/- with high protein diet (Diet B) as calculated

A mixed culture trail of mud crab (Scylla serrata Forskal) with tilapia ( Oreocromis niloticus L.)

A ten-month study on mixed culture of mud crab Scylla serrata with tilapia (Oreochromis niloticus) was performed in brackish water earthen ponds using live tilapia fry as the only feed for crab. The monthly growth rate varied from 9.07-19.llg among four treatments. Treatment T 1, cw: 0.68cm (±0.72) and bw: 19.11 gm (±12.97) showed highest performance which was followed by T 3, cw: 0.62cm (±0.60) and bw: 13.42 gm (±10.51), T4, cw: 0.65cm (±0.64) and bw: 13.20 gm (±9.89) and T2, cw: 0.36cm (± 0.25) and bw: 9.07 gm (±8.05). Highest survivability of crabs was also recorded in T 1 (21.5%) which was followed by T 2 (15.65%), T4 (14.95%) and T 3 (14.15%). In terms of survivability, significant differences (p<0.05) were observed among the treatments whereas these were recorded as insignificant difference (p<0.05) in final weight, weight gain and production of crabs and tilapia. Mixed culture of mud crab with tilapia could make more rewarding than crab monoculture but the study suggests that only tilapia fry can not fulfill the feed requirement of crabs in respects of survivability, final body weight and weight gain. Besides, existed salinity level of 4-12 ppt during experimental period might be the another key factor for low survivability and weight gain.

The potential of mixed culture of freshwater giant prawn Macrobrachium rosenbergii de Man and tiger shrimp Penaeus monodon Fab. at Khulna region, Bangladesh

The freshwater giant prawn (golda), Macrobrachium rosenbergii and tiger shrimp (bagda), Penaeus monodon were stocked together with or without fin fishes at different stocking rates in semi-saline waters at Khulna region and their growth, survival, yield and costreturn analysis were made. Survival rate of golda and bagda ranged from 23.0 to 36.8% and 8.2 to 24%, respectively. The both species were significantly affected by their own stocking density. The average final weight of golda and bagda ranged from 62.4 to 73.3 g and 32.0 to 66.4 g. The bivariate analysis of average final weight of both golda and bagda revealed that golda positively and bagda negatively influenced by the total stocking density. However, the results of the individual sizes of both golda and bagda showed an increase in the proportions of smaller animals and a decrease in the proportion of larger ones with increasing stocking rates. The harvesting weights of all animals in the experimental ghers were in marketable sizes although their prices varied with the individual size. The total production comprised of both golda and bagda ranged from 514.6 to 952.8 kg ha·1, over a culture period of 10 months. Return on investment ranged from 51.0 to 125.7%.

Over-wintering performance of mixed sex and monosex tilapia (Oreochromis niloticus L.) in Bangladesh

An experiment was conducted for six months in 6 experimental ponds (each size 80 of m2) to assess the over-wintering performance between mixed sex and monosex tilapia, Oreochromis niloticus. The experiment was carried out with two treatments each with three replicates. In the first treatment (T1), mixed sex tilapia were stocked in 3 ponds with a mean initial of 4.80±0.18 g. In the second treatment (T2), monosex tilapia were stocked in another 3 ponds with a mean initial weight of 4.81 ±0.20 g. Each pond was stocked with 250 fingerlings. Fish were fed at the rate of 6% of fish body weight at the beginning. The feeding rate was gradually reduced to 2% for the third month and finally increased to 3% for rest of the period. Water quality was monitored fortnightly and the ranges were: temperature17.86-29.10°C, dissolved oxygen 4.25-6.10 mg/1, pH 6.97-7.20 and transparency 24.10-36.50 cm. After 6 months of rearing monosex tilapia attained a significantly (p46.26±0.34 g compared to 112.40±0.36 g for mixed sex tilapia. Monosex tilapia also resulted in significantly (Pmixed sex tilapia. However, there was no significant (pmixed sex and monosex tilapia. The production of monosex tilapia (3723.10 kg/ha) was about 32% higher than that of mixed sex tilapia (2776.28 kg/ha). The net profit/ha generated from the 6 months culture period was calculated as Tk. 43,311.45 and. 69,277.32/- for mixed sex and monosex tilapia respectively. The results of the present study suggested that it is possible to successfully culture tilapia during the winter period and the culture of monosex tilapia is more profitable due to its higher growth rate than that of mixesex tilapia.