The fish community of East Cape tidal pools and an assessment of the nursery function of this habitat

Fish occurring in tidal pools in the lower balanoid zone near Port Elizabeth were examined by visual census and rotenone collections. Numerically, Clinidae constituted 28% of the community, Sparidae 23%, Gobiidae 17% and the Cheilodactylidae 12%, while eleven other families contributed to the remaining 20%. The 44 species recorded were classified as either residents (e.g. Clinidae or Gobiidae) or transients. The transient species were chiefly juvenile Sparidae, Cheilodactylidae and Mugllidae although numerous tropical vagrants also occurred in the summer months. Tidal pools, when compared with other coastal habitats, were found to be an important nursery area for some of the transient species, particularly Sparodon durbanensis, Diplodus cervinus hottentotus, Chirodactylus brachydactylus and Chellodactylus fasciatus

A description of the early life history stages of the kob, Argyrosomus hololepidotus (Pisces: Sciaenidae), from southern Africa

The larval development of the kob, Argyrosomus hoblepidotus is described and illustrated from a series of specimens collected in Algoa Bay, South Africa. Larvae are moderately deep bodied (BD = 30% BL) with a convex dorsal profile and trunk tapering to a narrow caudal peduncle. The head is large, increasing from 22% BL in preflexion larvae to 35% BL in juveniles. Pre-anal length increases from 37% BL in preflexion larvae to >60% in juveniles. Notochord flexion occurs at 5–6 mm BL. Argyrosomus hololepidotus larvae are characterized by melanophores behind the head, at the anal fin base, on the caudal fin, on the abdomen, in the angle of the jaw and at the jaw isthmus. Medio-lateral pigmentation increases markedly in early juveniles. Osteological development is described from a series of cleared and stained specimens. By 14 mm BL all fins have the adult complement of spines and rays. The larvae of A. hololepidotus are briefly compared with those of other Atlantic and Indo-Pacific sciaenids

The beach-seine fishery off durban, Kwazulu-Natal

The beach-seine fishery at Durban was investigated from July 1993 to June 1994. During this period the fishermen completed 270 hauls on 146 days of operation. In total, 119 species of fish as well as squid, cuttlefish and crabs were recorded in the catches. Most of these were small shoaling species belonging to the families Leiog-nathidae, Engraulidae and Clupeidae. Many species were caught at sizes below their reported size at first maturity. Based on this study and data from the National Marine Linefish System, there appears to be little overlap in the catches of the beach-seine netters and other fishery sectors in the area

A systematic evaluation of the incremental protection of broad-scale habitats at Ningaloo Reef, Western Australia

Incremental increases to marine conservation areas in response to changing goals, 15 policy, threats or new information are common practice world-wide. Ningaloo Reef, in 16 north-western Australia, is protected by the Ningaloo Marine Park (State Waters) which 17 was expanded incrementally in 2004 so that 34% of the park now comprises no-take 18 sanctuary zones. To test the hypothesis that all habitats (benthic cover types) at 19 Ningaloo are actually protected at this 34% level, a systematic conservation planning 20 exercise was conducted using existing broad-scale habitat data (as a surrogate for 21 marine biodiversity) and C-Plan decision-support software. Though subtidal and 22 intertidal coral communities were found to be adequately protected, other habitats, 23 particularly those in deeper waters seaward of the reef did not attain the 34% target. 24 Efficient incremental additions to the sanctuary zones to allow increased representation 25 of these under-represented habitats were explored with C-Plan. It is recommended that 26 systematic conservation planning incorporating new biodiversity and social information 27 (now becoming available) be undertaken for the next iteration of the Ningaloo Marine 28 Park management plan. This analysis at Ningaloo Reef serves as a useful example of a 29 post-hoc systematic approach to guide incremental expansion of existing marine 30 protected areas in other parts of the world.http://www.publish.csiro.au/nid/126.htmab201

Cross-shelf transport, oxygen depletion, and nitrate release within a forming mesoscale eddy in the eastern Indian Ocean

International audienceMesoscale eddies may drive a significant component of cross-shelf transport important in the ecology of shelf ecosystems and adjacent boundary currents. The Leeuwin Current in the eastern Indian Ocean becomes unstable in the austral autumn triggering the formation of eddies. We hypothesized that eddy formation represented the major driver of cross-shelf transport during the autumn. Acoustic Doppler Current Profiler profiles confirmed periodic offshore movement of 2 Sv of shelf waters into the forming eddy from the shelf, carrying a load of organic particles (>0.06 mm). The gap between inflow and outflow then closed, such that the eddy became isolated from further direct input of shelf waters. Drifter tracks supported an anticyclonic surface flow peaking at the eddy perimeter and decreasing in velocity at the eddy center. Oxygen and nutrient profiles suggested rapid remineralization of nitrate mid-depth in the isolated water mass as it rotated, with a total drawdown of oxygen of 3.6 mol m 22 to 350 m. Depletion of oxygen, and release of nitrate, occurred on the timescale of 1 week. We suggest that N supply and N turnover are rapid in this system, such that nitrate is acting primarily as a regenerated nutrient rather than as a source of new nitrogen. We hypothesize that sources of eddy particulate C and N could include particles sourced from coastal primary producers within 500 km such as macrophytes and sea-grasses known to produce copious detritus, which is prone to resuspension and offshore transport

Production and ecosystem structure in cold‐core vs. warm‐core eddies: Implications for the zooplankton isoscape and rock lobster larvae

Anticyclonic (warm-core) mesoscale eddies (WCEs) in the Eastern Indian Ocean carry higher surface chlorophyll signatures than cyclonic (cold-core) eddies (CCEs). Paradoxically, WCEs host rock lobster larvae (phyllosomas) with lower lipid stores and protein reserves than phyllosomas in CCEs, suggesting a poorer nutritional status. We assess primary productivity and zooplankton isotopic data from eight eddies across four research voyages (2003–2011) to determine how this contradiction might occur. We find that WCEs and CCEs are equally productive per unit chlorophyll a, but depth-integrated primary production (PP) is greater in eddies with shallower mixed layers (MLs), especially in CCEs. MLs tend to be shallower in CCEs than in WCEs because the pycnocline is closer to the surface. This, in combination with stronger stratification in CCE euphotic zones than those of WCEs, supports greater flagellate and dinoflagellate populations in CCEs. These phytoplankton provide high-quality nutrition for zooplankton, which feed on average ~ 0.6 trophic level lower in CCEs with the shallowest MLs, accumulating high lipid stores. Conversely, WCEs have, on average, ~ 70 m deeper MLs than CCEs, and host a phytoplankton community with more diatoms. Diatoms provide lower quality food for zooplankton, and zooplankton lipid stores in WCEs decline with trophic level, and possibly, with time after initial (or seasonal) nutrient injection. As a result, phyllosomas in CCEs have higher energy and lipid content than those in warm-core eddies. The resolution of the paradox, therefore, is that the higher surface chlorophyll signatures of WCEs are not representative of the nutritional value of the prey field of the phyllosoma. We also conclude that interannual variations of mixed layer depth occur at a regional scale, controlling PP

Phyllosomata associated with large gelatinous zooplankton: hitching rides and stealing bites

During a zooplankton survey 350 km off the coast of Western Australia, we captured a large and robust zooid of a salp (Thetys vagina), to which six late stage larvae (phyllosomata) of the western rock lobster (Panulirus cygnus) were attached. High-throughput sequencing analyses of DNA extracts from midgut glands of the larvae confirmed that each phyllosoma had consumed mainly salp tissue ( x 1⁄4 64.5% + 15.9 of DNA reads). These results resolve long-standing conjecture whether spiny lobster phyllosomata attach to large gelatinous hosts to feed on them

Biogeochemical and ecological impacts of boundary currents in the Indian Ocean

Monsoon forcing and the unique geomorphology of the Indian Ocean basin result in complex boundary currents, which are unique in many respects. In the northern Indian Ocean, several boundary current systems reverse seasonally. For example, upwelling coincident with northward-flowing currents along the coast of Oman during the Southwest Monsoon gives rise to high productivity which also alters nutrient stoichiometry and therefore, the species composition of the resulting phytoplankton blooms. During the Northeast Monsoon most of the northern Indian Ocean boundary currents reverse and favor downwelling. Higher trophic level species have evolved behavioral responses to these seasonally changing conditions. Examples from the western Arabian Sea include vertical feeding migrations of a copepod (Calanoides carinatus) and the reproductive cycle of a large pelagic fish (Scomberomorus commerson). The impacts of these seasonal current reversals and changes in upwelling and downwelling circulations are also manifested in West Indian coastal waters, where they influence dissolved oxygen concentrations and have been implicated in massive fish kills. The winds and boundary currents reverse seasonally in the Bay of Bengal, though the associated changes in upwelling and productivity are less pronounced. Nonetheless, their effects are observed on the East Indian shelf as, for example, seasonal changes in copepod abundance and zooplankton community structure. In contrast, south of Sri Lanka seasonal reversals in the boundary currents are associated with dramatic changes in the intensity of coastal upwelling, chlorophyll concentration, and catch per unit effort of fishes. Off the coast of Java, monsoon-driven changes in the currents and upwelling strongly impact chlorophyll concentrations, seasonal vertical migrations of zooplankton, and sardine catch in Bali Strait. In the southern hemisphere the Leeuwin is a downwelling-favorable current that flows southward along western Australia, though local wind forcing can lead to transient near shore current reversals and localized coastal upwelling. The poleward direction of this eastern boundary current is unique. Due to its high kinetic energy the Leeuwin Current sheds anomalous, relatively high chlorophyll, warm-core, downwelling eddies that transport coastal diatom communities westward into open ocean waters. Variations in the Leeuwin transport and eddy generation impact many higher trophic level species including the recruitment and fate of rock lobster (Panulirus cygnus) larvae. In contrast, the transport of the Agulhas Current is very large, with sources derived from the Mozambique Channel, the East Madagascar Current and the southwest Indian Ocean sub-gyre. Dynamically, the Agulhas Current is upwelling favorable; however, the spatial distribution of prominent surface manifestations of upwelling is controlled by local wind and topographic forcing. Meanders and eddies in the Agulhas Current propagate alongshore and interact with seasonal changes in the winds and topographic features. These give rise to seasonally variable localized upwelling and downwelling circulations with commensurate changes in primary production and higher trophic level responses. Due to the strong influence of the Agulhas Current, many neritic fish species in southeast Africa coastal waters have evolved highly selective behaviors and reproductive patterns for successful retention of planktonic eggs and larvae. For example, part of the Southern African sardine (Sardinops sagax) stock undergoes a remarkable northward migration enhanced by transient cyclonic eddies in the shoreward boundary of the Agulhas Current. There is evidence from the paleoceanographic record that these currents and their biogeochemical and ecological impacts have changed significantly over glacial to interglacial timescales. These changes are explored as a means of providing insight into the potential impacts of climate change in the Indian Ocean

Accommodating Dynamic Oceanographic Processes and Pelagic Biodiversity in Marine Conservation Planning

Pelagic ecosystems support a significant and vital component of the ocean's productivity and biodiversity. They are also heavily exploited and, as a result, are the focus of numerous spatial planning initiatives. Over the past decade, there has been increasing enthusiasm for protected areas as a tool for pelagic conservation, however, few have been implemented. Here we demonstrate an approach to plan protected areas that address the physical and biological dynamics typical of the pelagic realm. Specifically, we provide an example of an approach to planning protected areas that integrates pelagic and benthic conservation in the southern Benguela and Agulhas Bank ecosystems off South Africa. Our aim was to represent species of importance to fisheries and species of conservation concern within protected areas. In addition to representation, we ensured that protected areas were designed to consider pelagic dynamics, characterized from time-series data on key oceanographic processes, together with data on the abundance of small pelagic fishes. We found that, to have the highest likelihood of reaching conservation targets, protected area selection should be based on time-specific data rather than data averaged across time. More generally, we argue that innovative methods are needed to conserve ephemeral and dynamic pelagic biodiversity

A Decade of Incorporating Social Sciences in the Integrated Marine Biosphere Research Project (IMBeR): Much Done, Much to Do?

Successful management and mitigation of marine challenges depends on cooperation and knowledge sharing which often occurs across culturally diverse geographic regions. Global ocean science collaboration is therefore essential for developing global solutions. Building effective global research networks that can enable collaboration also need to ensure inter- and transdisciplinary research approaches to tackle complex marine socio-ecological challenges. To understand the contribution of interdisciplinary global research networks to solving these complex challenges, we use the Integrated Marine Biosphere Research (IMBeR) project as a case study. We investigated the diversity and characteristics of 1,827 scientists from 11 global regions who were attendees at different IMBeR global science engagement opportunities since 2009. We also determined the role of social science engagement in natural science based regional programmes (using key informants) and identified the potential for enhanced collaboration in the future. Event attendees were predominantly from western Europe, North America, and East Asia. But overall, in the global network, there was growing participation by females, students and early career researchers, and social scientists, thus assisting in moving toward interdisciplinarity in IMBeR research. The mainly natural science oriented regional programmes showed mixed success in engaging and collaborating with social scientists. This was mostly attributed to the largely natural science (i.e., biological, physical) goals and agendas of the programmes, and the lack of institutional support and push to initiate connections with social science. Recognising that social science research may not be relevant to all the aims and activities of all regional programmes, all researchers however, recognised the (potential) benefits of interdisciplinarity, which included broadening scientists’ understanding and perspectives, developing connections and interlinkages, and making science more useful. Pathways to achieve progress in regional programmes fell into four groups: specific funding, events to come together, within-programme-reflections, and social science champions. Future research programmes should have a strategic plan to be truly interdisciplinary, engaging natural and social sciences, as well as aiding early career professionals to actively engage in such programmes.This publication resulted in part from support from the U.S. National Science Foundation (Grant OCE-1840868) to the Scientific Committee on Oceanic Research (SCOR)