Crustacean Fauna in Association with Common Algae of Karachi Coastal Waters

Aspects of the structure (species composition and relative abundance, species associations and interactions, habitat preferences, species diversity and abundance relationships) of algal crustacean assemblages have been investigated from a range of algal types collected in clear Manora and Buleji waters. A total of 23 crustacean species were separated from algae at both the sites. Significant positive correlations between species were detected.


INTRODUCTION
P lant-animal relationships are attracting the attention of marine biologists for a long time. It is observed that food ingested by a grazer may affect the animal's growth and reproduction (Nicotri, 1977;Vadas, 1977) while the herbivores may affect the diversity, biomass and distribution of marine plants (Lubchenco, 1978;Raffaelli, 1979). Plants are also used by animals as refuge from predators and desiccation. The coastal areas of Karachi offer a variety of sandy beaches, rocky ledges, swampy wetlands and few islands. They are inhabited by a variety of marine benthic algae (Shameel and Tanaka, 1992;Shameel, 2001Shameel, , 2002Shameel, , 2008Shameel, , 2012. Pakistan presents a unique opportunity for phycological studies of the various avenues of researches in this direction (Valeem, 2004;Valeem and Shameel, 2008), the most fascinating and useful investigation is the study of algal association with marine fauna (Warmke and Almodovar, 1963;Lewis, 1984). To date, some studies on plant-animal relationship are found in Pakistan: Zehra et al. (1995a) conducted a study on molluscan epifauna on marine algae of Karachi. Zehra et al. (1995b) studied epifauna and monsoons on Sargassum virgatum. Biomass of animals and seaweeds was studied by Ahmed and Hameed (1999). Ghani and Nawaz (2000) investigated algal associated fauna of Manora mangroves. Barkati and Rahman (2005) likewise studied Sandspit, Clifton and Port Qasim mangroves for fauna including fauna of seaweeds found there. Baig and Zehra (1997, 2006 consecutively worked on seasonal variation of Caulerpa sp. and Sargassum sp. and associated faunas. Kazmi (2016) in a compendium on symbiotic crustaceans of Pakistan reported 270 symbiotic aquatic Crustacea from Pakistani area,of which at least 30 are algal associated.The present analysis was under taken based on the crustacean species associated with all the common algae found on the rocky shores of Manora and Buleji by Sadiq (1994). During this study of one year (June 1990to May 1991, 22 algal species were studied from the two collection sites. Besides crustaceans, the remaining groups were molluscs, polychaete worms, foraminiferans, nematodes, pycnogonids, bryozoans, cnidarians, ticks and mites, brittle stars, and starfish. The rocky shores of Manora and Buleji have a fairly rich algal growth confining to three main types: Chlorophycota (green algae), Phaeophycota (brown algae) and Rhodophycota (red algae). The most common algae seem to be Padina pavonica and Stockeyia indica at Manora, whereas Ulva fasciata and Sargassum virgatum are common O n l i n e

F i r s t A r t i c l e
at Buleji. Sapathoglossum variabile, Hypnea musciformis, Laurencia obtusa, Gracilaria andersonii, Iyengaria stellata and Endarachne binghamiae are less commonly found.
The material under study shows a predominance of crustaceans, which represents 70-80 % of the associated fauna in a given sample. The frequency of occurrence of crustacean groups is in the following descending order: Amphipoda, Isopoda, Copepoda, Tanaidacea, Ostracoda, Cumacea, Brachyura and Caridea. The same data with updated taxonomy and comparison is utilized here.

MATERIALS AND METHODS
During the study period from June 1990 to May 1991 monthly algal collections were obtained from Manora and Buleji at low tide. The non-random sampling was due to the patchy distribution of the plants. It was further noted that several species of algae grew side by side and that green and brown algae were mixed. Care was taken to obtain each species separately. During the study, salinity varied from 35 to 38%[T1]. At both collection sites, with a monthly mean at Buleji (35.5%)[T2] somewhat lower than at Manora (36%) [T3]. Water temperature at the two sites also varied from 22 to 30º C with a monthly mean at Buleji (24ºC) slightly lower than at Manora (25º C). The pH was similar at both collection sites ranged from 5 in November 1990 to 7 in April 1991.
Algal assemblages at both sites were quantified by the quadrate (l ft. sq) sampling technique with five samples per site per sampling date. Algal abundance varied seasonally at both the collection sites (Table I). For each month, the crustacean occurrence and dens ity of crustaceans is shown with the help of histograms. The relative abundance of epifaunal crustaceans to a particular alga was also studied. The known species are mostly illustrated and supported with brief note on each one. (Sars, 1904) ( Fig. 1a).

March April May
Manora

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Habitat: Found on Colpomenia sinousa, Sargassum virgatum, Ulva fasciata, Caulerpa taxifolia Iyengaria stellata and Padina pavonica.
Remark: Since only males are known from A. robusta (Churchill et al., 2014) the present females will be the first ever reported. Kornicker and Caraion, 1974 (Fig. 1f) Material Remark: Cymadusa filosa, long been considered a polymorphic, pantropical species, is in fact a species complex, and this situation has confused the generic concept.C. filosa name has been misapplied to some other species (Peart, 2004 (Barnard, 1955 (Larsen, 2002;Larsen and Froufe, 2013). Polymorphic males and ontogenetic variation present the most serious problems as regards intra-specific variation, while females display a cryptic nature in almost all species. Tirmizi and Kazmi, 1988 (Fig. 4b) Material

DISCUSSION
Species composition and relative abundance of crustacean fauna differed in the various algae (Table II). It was noted that basically a similar suite of crustaceans occurred on all plant species, faunal differences seen among algae were, however, due to the differences in the relative abundance of individual species on a particular organism.
The large size of seaweeds were collected during winter (present study), this may be one of the reason of abundant epifauna in winter found by Zehra et al. (1995).

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E.E. Valeem et al.    The present studies show that amphipods, which formed the major bulk of the algal fauna being 36 and 59% at Manora and Buleji, respectively, also exhibited the greatest differences in algae (Figs. 5,6). A few crustacean sp. showed strong algal prefere nce. Maximum number of amphipod species occurred on Stockeyia indica and Odonthalia washingtonensis, eight species could be identified out of which six species at Manora and Buleji (Fig. 5a, 6a). Cymadusa filosa, Elasmopus pectinicrus, Pseudocaprellina pambensis and Hemiaegina minuta were the most common on all types of algae, Cyproidea ornata was found mostly on Sargassum virgatum and Stockeyia O n l i n e

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E.E. Valeem et al. indica; Hemiaengia minuta occurred on Halimeda tuna, Sargassum virgatum and Stockeyia indica. For C. filosa the most common algal habitats were Sargassum dentifolium and Cystosaira crinite in the Red Sea (El-Sayed et al., 2014). The isopods showed striking differences of 42 and 5 % in algal fauna at Manora and Buleji respectively (Fig.  5b, 6b); four isopods: Synidotea indicus, Atarbolana setosa, Cirolana manorae and Paraimen tuberculata were common on all types of algae. Paranthura latipes was less frequently found on the algal samples. Relative abundance of isopods on Stockeyia indica, Padina pavonica and Caulerpa taxifolia were higher than found on other algal samples.
Copepods were the next most common group comprising 25 and 38% of the total algal fauna at Manora and Buleji, respectively (Fig. 5c, 6c). Four copepods Sacodiscus littoralis, Laophonte cornuta, Porcellidium fimbriatum fimbriatum and Metamphiascopsis hirsutus were most common and found abundantly on all types of algae.
Ostracods comprised 0.72 and 0.25 % of the algal fauna at Manora and Buleji, respectively (Fig. 5d, 6d), had the highest differences among plants. Cylindroleberis bacescui and Ancohenia robusta both were abundant on all the algae.
Carideans were found in abundance (60 %) in the month of April at Buleji, 27% in the month of June at Manora (Fig. 5e, 6e); brachyurans 28% in the month of march at Buleji, 37% in November at Manora (Fig. 5f, 6f); cumaceans 34% in the month of April at Buleji, 25% in the month of May at Manora (Fig. 5g, 6g); and tenaidaceans were found in abundance (30 %) in the month of December at Buleji while 24 % during the month of August were found at Manora respectively (Fig. 5h, 6h). Tanaidaceans had low relative abundance of 0.66 and 0.38% at the two collection sites.

Statement of conflict of interest
The authors have declared no conflict of interest.